diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 0fbd342d..1b6bd62a 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -102,7 +102,6 @@ jobs:
       fail-fast: false
       matrix:
         php-version:
-          - '8.0'
           - '8.1'
           - '8.2'
           - '8.3'
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 35d9587c..03039ea8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,12 +9,16 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - Added samples ([#218](https://github.com/opensearch-project/opensearch-php/pull/218))
 - Added support for PHP 8.3 and 8.4 ([#229](https://github.com/opensearch-project/opensearch-php/pull/229))
 ### Changed
+- Switched to PSR Interfaces
+- Increased PHP min version to 8.1
 - Increased min version of `ezimuel/ringphp` to `^1.2.2`
 - Changed fluent setters to return static
 ### Deprecated
 - Passing a callable to \OpenSearch\ClientBuilder::setEndpoint() is deprecated and replaced with passing an EndpointFactory to \OpenSearch\ClientBuilder::setEndpointFactory() ([#237](https://github.com/opensearch-project/opensearch-php/pull/237))
+- Connections, Connection pools and Selectors are deprecated. Use a PSR HTTP Client that supports retries instead.   
 ### Removed
-- Removed support for PHP 7.3 and 7.4
+- Removed support for PHP 7.3, 7.4 and 8.0.
+- Removed support for async requests which were never actually working.
 ### Fixed
 - Fixed PHP 8.4 deprecations
 ### Updated APIs
diff --git a/UPGRADING.md b/UPGRADING.md
new file mode 100644
index 00000000..33f30976
--- /dev/null
+++ b/UPGRADING.md
@@ -0,0 +1,109 @@
+- [Upgrading OpenSearch PHP Client](#upgrading-opensearch-php-client)
+    - [Upgrading to >= 2.0.0](#upgrading-to--240)
+        - [HTTP Client Auto-Discovery](#http-client-auto-discovery)
+        - [Configuring Guzzle HTTP Client in 2.x](#configuring-guzzle-http-client-in-2x)
+        - [Configuring Symfony HTTP Client in 2.x](#configuring-symfony-http-client-in-2x)
+
+# Upgrading OpenSearch PHP Client
+
+## Upgrading to >= 2.4.0
+
+openseach-php removes the hard-coded dependency on the [Guzzle HTTP client](https://docs.guzzlephp.org/en/stable/#) and switches to the following PSR interfaces: 
+
+- [PSR-7 HTTP message interfaces](https://www.php-fig.org/psr/psr-7/)
+- [PSR-17 HTTP Factories](https://www.php-fig.org/psr/psr-17/)
+- [PSR-18 HTTP Client](https://www.php-fig.org/psr/psr-18/)
+
+You can continue to use Guzzle, but will need to configure it as a PSR-18 HTTP Client.
+
+### HTTP Client Auto-Discovery
+
+opensearch-php 2.x will try and discover and install a PSR HTTP Client using [PHP-HTTP Discovery](https://docs.php-http.org/en/latest/discovery.html) 
+if one is not explicitly provided.
+
+```php
+$transport = (new \OpenSearch\TransportFactory())->create();
+$endpointFactory = new \OpenSearch\EndpointFactory();
+$client = new Client($transport, $endpointFactory, []);
+
+// Send a request to the 'info' endpoint.
+$info = $client->info();
+```
+
+### Configuring Guzzle HTTP Client in 2.x
+
+To configure Guzzle as a PSR HTTP Client with the similar configuration to opensearch 1.x you can use the following example:
+
+```php
+$guzzleClient = new \GuzzleHttp\Client([
+    'base_uri' => 'https://localhost:9200',
+    'auth' => ['admin', getenv('OPENSEARCH_PASSWORD')],
+    'verify' => false,
+    'retries' => 2,
+    'headers' => [
+        'Accept' => 'application/json',
+        'Content-Type' => 'application/json',
+        'User-Agent' => sprintf('opensearch-php/%s (%s; PHP %s)', \OpenSearch\Client::VERSION, PHP_OS, PHP_VERSION),
+    ]
+]);
+
+$guzzleHttpFactory = new \GuzzleHttp\Psr7\HttpFactory();
+
+$serializer = new \OpenSearch\Serializers\SmartSerializer();
+
+$requestFactory = new \OpenSearch\RequestFactory(
+    $guzzleHttpFactory,
+    $guzzleHttpFactory,
+    $guzzleHttpFactory,
+    $serializer,
+);
+
+$transport = (new OpenSearch\TransportFactory())
+    ->setHttpClient($guzzleClient)
+    ->setRequestFactory($requestFactory)
+    ->create();
+
+$endpointFactory = new \OpenSearch\EndpointFactory();
+$client = new \OpenSearch\Client($transport, $endpointFactory, []);
+
+// Send a request to the 'info' endpoint.
+$info = $client->info();
+```
+
+### Configuring Symfony HTTP Client in 2.x
+
+You can configure [Symfony HTTP Client](https://symfony.com/doc/current/http_client.html) as a PSR HTTP Client using
+the following example:
+
+```php
+$symfonyPsr18Client = (new \Symfony\Component\HttpClient\Psr18Client())->withOptions([
+    'base_uri' => 'https://localhost:9200',
+    'auth_basic' => ['admin', getenv('OPENSEARCH_PASSWORD')],
+    'verify_peer' => false,
+    'max_retries' => 2,
+    'headers' => [
+        'Accept' => 'application/json',
+        'Content-Type' => 'application/json',
+    ],
+]);
+
+$serializer = new \OpenSearch\Serializers\SmartSerializer();
+
+$requestFactory = new \OpenSearch\RequestFactory(
+    $symfonyPsr18Client,
+    $symfonyPsr18Client,
+    $symfonyPsr18Client,
+    $serializer,
+);
+
+$transport = (new \OpenSearch\TransportFactory())
+    ->setHttpClient($symfonyPsr18Client)
+    ->setRequestFactory($requestFactory)
+    ->create();
+
+$client = new \OpenSearch\Client($transport, $endpointFactory, []);
+
+// Send a request to the 'info' endpoint.
+$info = $client->info();
+
+```
diff --git a/composer.json b/composer.json
index dee24ad8..5e227710 100644
--- a/composer.json
+++ b/composer.json
@@ -21,22 +21,32 @@
     }
   ],
   "require": {
-    "php": "^8.0",
+    "php": "^8.1",
     "ext-json": ">=1.3.7",
     "ext-curl": "*",
     "ezimuel/ringphp": "^1.2.2",
-    "psr/log": "^1|^2|^3",
+    "php-http/discovery": "^1.20",
+    "psr/http-client": "^1.0",
+    "psr/http-client-implementation": "*",
+    "psr/http-factory": "^1.1",
+    "psr/http-factory-implementation": "*",
+    "psr/http-message": "^2.0",
+    "psr/http-message-implementation": "*",
+    "psr/log": "^2|^3",
     "symfony/yaml": "*"
   },
   "require-dev": {
     "ext-zip": "*",
     "aws/aws-sdk-php": "^3.0",
-    "friendsofphp/php-cs-fixer": "^3.0",
-    "mockery/mockery": "^1.2",
-    "phpstan/phpstan": "^1.7.15",
-    "phpstan/phpstan-mockery": "^1.1.0",
-    "phpunit/phpunit": "^9.3",
-    "symfony/finder": "~4.0 || ~5.0"
+    "friendsofphp/php-cs-fixer": "^v3.64",
+    "guzzlehttp/psr7": "^2.7",
+    "mockery/mockery": "^1.6",
+    "phpstan/phpstan": "^1.12",
+    "phpstan/phpstan-mockery": "^1.1",
+    "phpunit/phpunit": "^9.6",
+    "symfony/finder": "^6.4|^7.0",
+    "symfony/http-client": "^6.4|^7.0",
+    "symfony/http-client-contracts": "^3.0"
   },
   "suggest": {
     "monolog/monolog": "Allows for client-level logging and tracing",
@@ -54,7 +64,10 @@
     }
   },
   "config": {
-    "sort-packages": true
+    "sort-packages": true,
+    "allow-plugins": {
+      "php-http/discovery": true
+    }
   },
   "scripts": {
     "php-cs": [
diff --git a/samples/index.php b/samples/index.php
index b7bb97f8..266be954 100644
--- a/samples/index.php
+++ b/samples/index.php
@@ -7,15 +7,79 @@
 
 require_once __DIR__ . '/vendor/autoload.php';
 
-$client = OpenSearch\ClientBuilder::fromConfig([
-   'Hosts' => [
-      'https://localhost:9200'
-   ],
-   'BasicAuthentication' => ['admin', getenv('OPENSEARCH_PASSWORD')],
-   'Retries' => 2,
-   'SSLVerification' => false
+// Auto-configure by discovery example
+
+$transport = (new \OpenSearch\TransportFactory())->create();
+$endpointFactory = new \OpenSearch\EndpointFactory();
+$client = new \OpenSearch\Client($transport, $endpointFactory, []);
+
+// Send a request to the 'info' endpoint.
+$info = $client->info();
+
+// Guzzle example
+
+$guzzleClient = new \GuzzleHttp\Client([
+    'base_uri' => 'https://localhost:9200',
+    'auth' => ['admin', getenv('OPENSEARCH_PASSWORD')],
+    'verify' => false,
+    'retries' => 2,
+    'headers' => [
+        'Accept' => 'application/json',
+        'Content-Type' => 'application/json',
+        'User-Agent' => sprintf('opensearch-php/%s (%s; PHP %s)', \OpenSearch\Client::VERSION, PHP_OS, PHP_VERSION),
+    ]
 ]);
 
+$guzzleHttpFactory = new \GuzzleHttp\Psr7\HttpFactory();
+
+$serializer = new \OpenSearch\Serializers\SmartSerializer();
+
+$requestFactory = new \OpenSearch\RequestFactory(
+    $guzzleHttpFactory,
+    $guzzleHttpFactory,
+    $guzzleHttpFactory,
+    $serializer,
+);
+
+$transport = (new OpenSearch\TransportFactory())
+    ->setHttpClient($guzzleClient)
+    ->setRequestFactory($requestFactory)
+    ->create();
+
+$endpointFactory = new \OpenSearch\EndpointFactory();
+$client = new \OpenSearch\Client($transport, $endpointFactory, []);
+
+// Send a request to the 'info' endpoint.
 $info = $client->info();
 
-echo "{$info['version']['distribution']}: {$info['version']['number']}\n";
+// Symfony example
+
+$symfonyPsr18Client = (new \Symfony\Component\HttpClient\Psr18Client())->withOptions([
+    'base_uri' => 'https://localhost:9200',
+    'auth_basic' => ['admin', getenv('OPENSEARCH_PASSWORD')],
+    'verify_peer' => false,
+    'max_retries' => 2,
+    'headers' => [
+        'Accept' => 'application/json',
+        'Content-Type' => 'application/json',
+    ],
+]);
+
+$serializer = new \OpenSearch\Serializers\SmartSerializer();
+
+$requestFactory = new \OpenSearch\RequestFactory(
+    $symfonyPsr18Client,
+    $symfonyPsr18Client,
+    $symfonyPsr18Client,
+    $serializer,
+);
+
+$transport = (new \OpenSearch\TransportFactory())
+    ->setHttpClient($symfonyPsr18Client)
+    ->setRequestFactory($requestFactory)
+    ->create();
+
+$client = new \OpenSearch\Client($transport, $endpointFactory, []);
+
+// Send a request to the 'info' endpoint.
+$info = $client->info();
diff --git a/src/OpenSearch/Aws/SigningClientDecorator.php b/src/OpenSearch/Aws/SigningClientDecorator.php
new file mode 100644
index 00000000..e54752f3
--- /dev/null
+++ b/src/OpenSearch/Aws/SigningClientDecorator.php
@@ -0,0 +1,29 @@
+<?php
+
+namespace OpenSearch\Aws;
+
+use Aws\Credentials\CredentialsInterface;
+use Aws\Signature\SignatureInterface;
+use Psr\Http\Client\ClientInterface;
+use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\ResponseInterface;
+
+/**
+ * A decorator client that signs requests using the provided AWS credentials and signer.
+ */
+class SigningClientDecorator implements ClientInterface
+{
+    public function __construct(
+        protected ClientInterface $inner,
+        protected CredentialsInterface $credentials,
+        protected SignatureInterface $signer,
+    ) {
+    }
+
+    public function sendRequest(RequestInterface $request): ResponseInterface
+    {
+        $request = $request->withHeader('x-amz-content-sha256', hash('sha256', (string) $request->getBody()));
+        $request = $this->signer->signRequest($request, $this->credentials);
+        return $this->inner->sendRequest($request);
+    }
+}
diff --git a/src/OpenSearch/Client.php b/src/OpenSearch/Client.php
index 580fe032..ae6cbb29 100644
--- a/src/OpenSearch/Client.php
+++ b/src/OpenSearch/Client.php
@@ -75,6 +75,8 @@ class Client
      */
     public $transport;
 
+    private TransportInterface $httpTransport;
+
     /**
      * @var array
      */
@@ -263,13 +265,19 @@ class Client
     /**
      * Client constructor
      *
-     * @param Transport $transport
+     * @param \OpenSearch\TransportInterface|\OpenSearch\Transport $transport
      * @param callable|EndpointFactoryInterface $endpointFactory
      * @param NamespaceBuilderInterface[] $registeredNamespaces
      */
-    public function __construct(Transport $transport, callable|EndpointFactoryInterface $endpointFactory, array $registeredNamespaces)
+    public function __construct(TransportInterface|Transport $transport, callable|EndpointFactoryInterface $endpointFactory, array $registeredNamespaces)
     {
-        $this->transport = $transport;
+        if (!$transport instanceof TransportInterface) {
+            @trigger_error('Passing an instance of \OpenSearch\Transport to ' . __METHOD__ . '() is deprecated in 2.3.2 and will be removed in 3.0.0. Pass an instance of \OpenSearch\TransportInterface instead.', E_USER_DEPRECATED);
+            $this->transport = $transport;
+            $this->httpTransport = new LegacyTransportWrapper($transport);
+        } else {
+            $this->httpTransport = $transport;
+        }
         if (is_callable($endpointFactory)) {
             @trigger_error('Passing a callable as the $endpointFactory param in ' . __METHOD__ . ' is deprecated in 2.3.2 and will be removed in 3.0.0. Pass an instance of \OpenSearch\EndpointFactoryInterface instead.', E_USER_DEPRECATED);
             $endpoints = $endpointFactory;
@@ -2063,33 +2071,36 @@ public function extractArgument(array &$params, string $arg)
 
     /**
      * Sends a raw request to the cluster
-     * @return callable|array
-     * @throws NoNodesAvailableException
+     * @return array|string|null
+     * @throws \Exception
      */
-    public function request(string $method, string $uri, array $attributes = [])
+    public function request(string $method, string $uri, array $attributes = []): array|string|null
     {
         $params = $attributes['params'] ?? [];
         $body = $attributes['body'] ?? null;
         $options = $attributes['options'] ?? [];
 
-        $promise = $this->transport->performRequest($method, $uri, $params, $body, $options);
-
-        return $this->transport->resultOrFuture($promise, $options);
+        return $this->httpTransport->sendRequest($method, $uri, $params, $body, $options['headers'] ?? []);
     }
 
     /**
-     * @return callable|array
+     * Sends a request for the given endpoint.
+     *
+     * @param \OpenSearch\Endpoints\AbstractEndpoint $endpoint
+     *
+     * @return array|string|null
+     *
+     * @throws \Exception
      */
-    private function performRequest(AbstractEndpoint $endpoint)
+    private function performRequest(AbstractEndpoint $endpoint): array|string|null
     {
-        $promise =  $this->transport->performRequest(
+        $options = $endpoint->getOptions();
+        return $this->httpTransport->sendRequest(
             $endpoint->getMethod(),
             $endpoint->getURI(),
             $endpoint->getParams(),
             $endpoint->getBody(),
-            $endpoint->getOptions()
+            $options['headers'] ?? []
         );
-
-        return $this->transport->resultOrFuture($promise, $endpoint->getOptions());
     }
 }
diff --git a/src/OpenSearch/ClientBuilder.php b/src/OpenSearch/ClientBuilder.php
index a075e36f..da41753b 100644
--- a/src/OpenSearch/ClientBuilder.php
+++ b/src/OpenSearch/ClientBuilder.php
@@ -45,6 +45,11 @@
 use Psr\Log\NullLogger;
 use ReflectionClass;
 
+@trigger_error(ClientBuilder::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 class ClientBuilder
 {
     public const ALLOWED_METHODS_FROM_CONFIG = ['includePortInHostHeader'];
diff --git a/src/OpenSearch/ClientFactory.php b/src/OpenSearch/ClientFactory.php
new file mode 100644
index 00000000..f94f2605
--- /dev/null
+++ b/src/OpenSearch/ClientFactory.php
@@ -0,0 +1,19 @@
+<?php
+
+namespace OpenSearch;
+
+class ClientFactory
+{
+    public function __construct(
+        protected TransportInterface $transport,
+        protected EndpointFactoryInterface $endpointFactory,
+        protected array $registeredNamespaces = [],
+    ) {
+    }
+
+    public function createClient(): Client
+    {
+        return new Client($this->transport, $this->endpointFactory, $this->registeredNamespaces);
+    }
+
+}
diff --git a/src/OpenSearch/Common/EmptyLogger.php b/src/OpenSearch/Common/EmptyLogger.php
index c2bfeaf4..d44f8166 100644
--- a/src/OpenSearch/Common/EmptyLogger.php
+++ b/src/OpenSearch/Common/EmptyLogger.php
@@ -24,11 +24,15 @@
 use Psr\Log\AbstractLogger;
 use Psr\Log\LoggerInterface;
 
+@trigger_error(EmptyLogger::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0. Use Psr\Log\NullLogger instead', E_USER_DEPRECATED);
+
 /**
  * Class EmptyLogger
  *
  * Logger that doesn't do anything.  Similar to Monolog's NullHandler,
  * but avoids the overhead of partially loading Monolog
+ *
+ * @deprecated in 2.3.2 and will be removed in 3.0.0. Use Psr\Log\NullLogger instead.
  */
 class EmptyLogger extends AbstractLogger implements LoggerInterface
 {
diff --git a/src/OpenSearch/Common/Exceptions/AuthenticationConfigException.php b/src/OpenSearch/Common/Exceptions/AuthenticationConfigException.php
index 7b070a1a..28afa295 100644
--- a/src/OpenSearch/Common/Exceptions/AuthenticationConfigException.php
+++ b/src/OpenSearch/Common/Exceptions/AuthenticationConfigException.php
@@ -22,6 +22,11 @@
 
 namespace OpenSearch\Common\Exceptions;
 
+@trigger_error(AuthenticationConfigException::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 class AuthenticationConfigException extends \RuntimeException implements OpenSearchException
 {
 }
diff --git a/src/OpenSearch/Common/Exceptions/BadMethodCallException.php b/src/OpenSearch/Common/Exceptions/BadMethodCallException.php
index 62b6551d..0dfe1fec 100644
--- a/src/OpenSearch/Common/Exceptions/BadMethodCallException.php
+++ b/src/OpenSearch/Common/Exceptions/BadMethodCallException.php
@@ -21,10 +21,14 @@
 
 namespace OpenSearch\Common\Exceptions;
 
+@trigger_error(BadMethodCallException::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
 /**
  * BadMethodCallException
  *
  * Denote problems with a method call (e.g. incorrect number of arguments)
+ *
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
  */
 class BadMethodCallException extends \BadMethodCallException implements OpenSearchException
 {
diff --git a/src/OpenSearch/Common/Exceptions/BadRequest400Exception.php b/src/OpenSearch/Common/Exceptions/BadRequest400Exception.php
index 11480bfd..ac232f01 100644
--- a/src/OpenSearch/Common/Exceptions/BadRequest400Exception.php
+++ b/src/OpenSearch/Common/Exceptions/BadRequest400Exception.php
@@ -21,6 +21,11 @@
 
 namespace OpenSearch\Common\Exceptions;
 
+@trigger_error(BadRequest400Exception::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 class BadRequest400Exception extends \Exception implements OpenSearchException
 {
 }
diff --git a/src/OpenSearch/Common/Exceptions/ClientErrorResponseException.php b/src/OpenSearch/Common/Exceptions/ClientErrorResponseException.php
index 3982d81f..884e00f2 100644
--- a/src/OpenSearch/Common/Exceptions/ClientErrorResponseException.php
+++ b/src/OpenSearch/Common/Exceptions/ClientErrorResponseException.php
@@ -21,6 +21,11 @@
 
 namespace OpenSearch\Common\Exceptions;
 
+@trigger_error(ClientErrorResponseException::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 class ClientErrorResponseException extends TransportException implements OpenSearchException
 {
 }
diff --git a/src/OpenSearch/Common/Exceptions/Conflict409Exception.php b/src/OpenSearch/Common/Exceptions/Conflict409Exception.php
index 215b8035..36e6ed34 100644
--- a/src/OpenSearch/Common/Exceptions/Conflict409Exception.php
+++ b/src/OpenSearch/Common/Exceptions/Conflict409Exception.php
@@ -21,6 +21,11 @@
 
 namespace OpenSearch\Common\Exceptions;
 
+@trigger_error(Conflict409Exception::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 class Conflict409Exception extends \Exception implements OpenSearchException
 {
 }
diff --git a/src/OpenSearch/Common/Exceptions/Curl/CouldNotConnectToHost.php b/src/OpenSearch/Common/Exceptions/Curl/CouldNotConnectToHost.php
index 63ab1834..7f95c944 100644
--- a/src/OpenSearch/Common/Exceptions/Curl/CouldNotConnectToHost.php
+++ b/src/OpenSearch/Common/Exceptions/Curl/CouldNotConnectToHost.php
@@ -25,6 +25,11 @@
 use OpenSearch\Common\Exceptions\OpenSearchException;
 use OpenSearch\Common\Exceptions\TransportException;
 
+@trigger_error(CouldNotConnectToHost::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 class CouldNotConnectToHost extends TransportException implements OpenSearchException
 {
 }
diff --git a/src/OpenSearch/Common/Exceptions/Curl/CouldNotResolveHostException.php b/src/OpenSearch/Common/Exceptions/Curl/CouldNotResolveHostException.php
index ac4cc9c0..3b6a5417 100644
--- a/src/OpenSearch/Common/Exceptions/Curl/CouldNotResolveHostException.php
+++ b/src/OpenSearch/Common/Exceptions/Curl/CouldNotResolveHostException.php
@@ -24,6 +24,11 @@
 use OpenSearch\Common\Exceptions\OpenSearchException;
 use OpenSearch\Common\Exceptions\TransportException;
 
+@trigger_error(CouldNotResolveHostException::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 class CouldNotResolveHostException extends TransportException implements OpenSearchException
 {
 }
diff --git a/src/OpenSearch/Common/Exceptions/Curl/OperationTimeoutException.php b/src/OpenSearch/Common/Exceptions/Curl/OperationTimeoutException.php
index f009d132..19bf5fc5 100644
--- a/src/OpenSearch/Common/Exceptions/Curl/OperationTimeoutException.php
+++ b/src/OpenSearch/Common/Exceptions/Curl/OperationTimeoutException.php
@@ -24,6 +24,11 @@
 use OpenSearch\Common\Exceptions\OpenSearchException;
 use OpenSearch\Common\Exceptions\TransportException;
 
+@trigger_error(OperationTimeoutException::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 class OperationTimeoutException extends TransportException implements OpenSearchException
 {
 }
diff --git a/src/OpenSearch/Common/Exceptions/Forbidden403Exception.php b/src/OpenSearch/Common/Exceptions/Forbidden403Exception.php
index e6cc8d6a..8a307cd0 100644
--- a/src/OpenSearch/Common/Exceptions/Forbidden403Exception.php
+++ b/src/OpenSearch/Common/Exceptions/Forbidden403Exception.php
@@ -21,6 +21,11 @@
 
 namespace OpenSearch\Common\Exceptions;
 
+@trigger_error(Forbidden403Exception::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 class Forbidden403Exception extends \Exception implements OpenSearchException
 {
 }
diff --git a/src/OpenSearch/Common/Exceptions/InvalidArgumentException.php b/src/OpenSearch/Common/Exceptions/InvalidArgumentException.php
index 78a12f1e..0ff06b20 100644
--- a/src/OpenSearch/Common/Exceptions/InvalidArgumentException.php
+++ b/src/OpenSearch/Common/Exceptions/InvalidArgumentException.php
@@ -21,6 +21,11 @@
 
 namespace OpenSearch\Common\Exceptions;
 
+@trigger_error(InvalidArgumentException::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 class InvalidArgumentException extends \InvalidArgumentException implements OpenSearchException
 {
 }
diff --git a/src/OpenSearch/Common/Exceptions/MaxRetriesException.php b/src/OpenSearch/Common/Exceptions/MaxRetriesException.php
index fc1eb71c..9d4be5fa 100644
--- a/src/OpenSearch/Common/Exceptions/MaxRetriesException.php
+++ b/src/OpenSearch/Common/Exceptions/MaxRetriesException.php
@@ -21,6 +21,11 @@
 
 namespace OpenSearch\Common\Exceptions;
 
+@trigger_error(MaxRetriesException::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 class MaxRetriesException extends TransportException implements OpenSearchException
 {
 }
diff --git a/src/OpenSearch/Common/Exceptions/Missing404Exception.php b/src/OpenSearch/Common/Exceptions/Missing404Exception.php
index 7105f475..c9b69be7 100644
--- a/src/OpenSearch/Common/Exceptions/Missing404Exception.php
+++ b/src/OpenSearch/Common/Exceptions/Missing404Exception.php
@@ -21,6 +21,11 @@
 
 namespace OpenSearch\Common\Exceptions;
 
+@trigger_error(Missing404Exception::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 class Missing404Exception extends \Exception implements OpenSearchException
 {
 }
diff --git a/src/OpenSearch/Common/Exceptions/NoDocumentsToGetException.php b/src/OpenSearch/Common/Exceptions/NoDocumentsToGetException.php
index 8bd30eed..82fdd9fa 100644
--- a/src/OpenSearch/Common/Exceptions/NoDocumentsToGetException.php
+++ b/src/OpenSearch/Common/Exceptions/NoDocumentsToGetException.php
@@ -21,6 +21,11 @@
 
 namespace OpenSearch\Common\Exceptions;
 
+@trigger_error(NoDocumentsToGetException::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 class NoDocumentsToGetException extends ServerErrorResponseException implements OpenSearchException
 {
 }
diff --git a/src/OpenSearch/Common/Exceptions/RequestTimeout408Exception.php b/src/OpenSearch/Common/Exceptions/RequestTimeout408Exception.php
index 80e26aa7..0892ea13 100644
--- a/src/OpenSearch/Common/Exceptions/RequestTimeout408Exception.php
+++ b/src/OpenSearch/Common/Exceptions/RequestTimeout408Exception.php
@@ -21,6 +21,11 @@
 
 namespace OpenSearch\Common\Exceptions;
 
+@trigger_error(RequestTimeout408Exception::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 class RequestTimeout408Exception extends BadRequest400Exception implements OpenSearchException
 {
 }
diff --git a/src/OpenSearch/ConnectionPool/AbstractConnectionPool.php b/src/OpenSearch/ConnectionPool/AbstractConnectionPool.php
index 7d0ea6a6..ecb0f0b6 100644
--- a/src/OpenSearch/ConnectionPool/AbstractConnectionPool.php
+++ b/src/OpenSearch/ConnectionPool/AbstractConnectionPool.php
@@ -26,6 +26,11 @@
 use OpenSearch\Connections\ConnectionFactoryInterface;
 use OpenSearch\Connections\ConnectionInterface;
 
+@trigger_error(AbstractConnectionPool::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 abstract class AbstractConnectionPool implements ConnectionPoolInterface
 {
     /**
diff --git a/src/OpenSearch/ConnectionPool/ConnectionPoolInterface.php b/src/OpenSearch/ConnectionPool/ConnectionPoolInterface.php
index 42917d51..0c5da67d 100644
--- a/src/OpenSearch/ConnectionPool/ConnectionPoolInterface.php
+++ b/src/OpenSearch/ConnectionPool/ConnectionPoolInterface.php
@@ -23,6 +23,11 @@
 
 use OpenSearch\Connections\ConnectionInterface;
 
+@trigger_error(ConnectionPoolInterface::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 interface ConnectionPoolInterface
 {
     public function nextConnection(bool $force = false): ConnectionInterface;
diff --git a/src/OpenSearch/ConnectionPool/Selectors/RandomSelector.php b/src/OpenSearch/ConnectionPool/Selectors/RandomSelector.php
index ecb7b380..557a9063 100644
--- a/src/OpenSearch/ConnectionPool/Selectors/RandomSelector.php
+++ b/src/OpenSearch/ConnectionPool/Selectors/RandomSelector.php
@@ -23,6 +23,11 @@
 
 use OpenSearch\Connections\ConnectionInterface;
 
+@trigger_error(RandomSelector::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 class RandomSelector implements SelectorInterface
 {
     /**
diff --git a/src/OpenSearch/ConnectionPool/Selectors/RoundRobinSelector.php b/src/OpenSearch/ConnectionPool/Selectors/RoundRobinSelector.php
index 8daeef60..1c0204bc 100644
--- a/src/OpenSearch/ConnectionPool/Selectors/RoundRobinSelector.php
+++ b/src/OpenSearch/ConnectionPool/Selectors/RoundRobinSelector.php
@@ -23,6 +23,11 @@
 
 use OpenSearch\Connections\ConnectionInterface;
 
+@trigger_error(RoundRobinSelector::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 class RoundRobinSelector implements SelectorInterface
 {
     /**
diff --git a/src/OpenSearch/ConnectionPool/Selectors/SelectorInterface.php b/src/OpenSearch/ConnectionPool/Selectors/SelectorInterface.php
index eeb29086..2d7ba1f2 100644
--- a/src/OpenSearch/ConnectionPool/Selectors/SelectorInterface.php
+++ b/src/OpenSearch/ConnectionPool/Selectors/SelectorInterface.php
@@ -23,6 +23,11 @@
 
 use OpenSearch\Connections\ConnectionInterface;
 
+@trigger_error(SelectorInterface::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 interface SelectorInterface
 {
     /**
diff --git a/src/OpenSearch/ConnectionPool/Selectors/StickyRoundRobinSelector.php b/src/OpenSearch/ConnectionPool/Selectors/StickyRoundRobinSelector.php
index 7da041a0..5091ac40 100644
--- a/src/OpenSearch/ConnectionPool/Selectors/StickyRoundRobinSelector.php
+++ b/src/OpenSearch/ConnectionPool/Selectors/StickyRoundRobinSelector.php
@@ -23,6 +23,11 @@
 
 use OpenSearch\Connections\ConnectionInterface;
 
+@trigger_error(StickyRoundRobinSelector::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 class StickyRoundRobinSelector implements SelectorInterface
 {
     /**
diff --git a/src/OpenSearch/ConnectionPool/SimpleConnectionPool.php b/src/OpenSearch/ConnectionPool/SimpleConnectionPool.php
index 29c14d26..0108a3e6 100644
--- a/src/OpenSearch/ConnectionPool/SimpleConnectionPool.php
+++ b/src/OpenSearch/ConnectionPool/SimpleConnectionPool.php
@@ -22,10 +22,14 @@
 namespace OpenSearch\ConnectionPool;
 
 use OpenSearch\ConnectionPool\Selectors\SelectorInterface;
-use OpenSearch\Connections\Connection;
 use OpenSearch\Connections\ConnectionFactoryInterface;
 use OpenSearch\Connections\ConnectionInterface;
 
+@trigger_error(SimpleConnectionPool::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 class SimpleConnectionPool extends AbstractConnectionPool implements ConnectionPoolInterface
 {
     /**
diff --git a/src/OpenSearch/ConnectionPool/SniffingConnectionPool.php b/src/OpenSearch/ConnectionPool/SniffingConnectionPool.php
index 2c6d6b83..d27d1228 100644
--- a/src/OpenSearch/ConnectionPool/SniffingConnectionPool.php
+++ b/src/OpenSearch/ConnectionPool/SniffingConnectionPool.php
@@ -28,6 +28,11 @@
 use OpenSearch\Connections\ConnectionFactoryInterface;
 use OpenSearch\Connections\ConnectionInterface;
 
+@trigger_error(SniffingConnectionPool::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 class SniffingConnectionPool extends AbstractConnectionPool
 {
     /**
diff --git a/src/OpenSearch/ConnectionPool/StaticConnectionPool.php b/src/OpenSearch/ConnectionPool/StaticConnectionPool.php
index c074e8c8..0f16fbe6 100644
--- a/src/OpenSearch/ConnectionPool/StaticConnectionPool.php
+++ b/src/OpenSearch/ConnectionPool/StaticConnectionPool.php
@@ -24,9 +24,14 @@
 use OpenSearch\Common\Exceptions\NoNodesAvailableException;
 use OpenSearch\ConnectionPool\Selectors\SelectorInterface;
 use OpenSearch\Connections\Connection;
-use OpenSearch\Connections\ConnectionInterface;
 use OpenSearch\Connections\ConnectionFactoryInterface;
+use OpenSearch\Connections\ConnectionInterface;
+
+@trigger_error(StaticConnectionPool::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
 
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 class StaticConnectionPool extends AbstractConnectionPool implements ConnectionPoolInterface
 {
     /**
diff --git a/src/OpenSearch/ConnectionPool/StaticNoPingConnectionPool.php b/src/OpenSearch/ConnectionPool/StaticNoPingConnectionPool.php
index a4a85e32..9b3b6001 100644
--- a/src/OpenSearch/ConnectionPool/StaticNoPingConnectionPool.php
+++ b/src/OpenSearch/ConnectionPool/StaticNoPingConnectionPool.php
@@ -24,9 +24,14 @@
 use OpenSearch\Common\Exceptions\NoNodesAvailableException;
 use OpenSearch\ConnectionPool\Selectors\SelectorInterface;
 use OpenSearch\Connections\Connection;
-use OpenSearch\Connections\ConnectionInterface;
 use OpenSearch\Connections\ConnectionFactoryInterface;
+use OpenSearch\Connections\ConnectionInterface;
+
+@trigger_error(StaticNoPingConnectionPool::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
 
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 class StaticNoPingConnectionPool extends AbstractConnectionPool implements ConnectionPoolInterface
 {
     /**
diff --git a/src/OpenSearch/Connections/Connection.php b/src/OpenSearch/Connections/Connection.php
index 7279f56c..653a1bcb 100644
--- a/src/OpenSearch/Connections/Connection.php
+++ b/src/OpenSearch/Connections/Connection.php
@@ -21,18 +21,22 @@
 
 namespace OpenSearch\Connections;
 
+use Exception;
+use GuzzleHttp\Ring\Core;
+use GuzzleHttp\Ring\Exception\ConnectException;
+use GuzzleHttp\Ring\Exception\RingException;
 use OpenSearch\Client;
 use OpenSearch\Common\Exceptions\BadRequest400Exception;
 use OpenSearch\Common\Exceptions\Conflict409Exception;
 use OpenSearch\Common\Exceptions\Curl\CouldNotConnectToHost;
 use OpenSearch\Common\Exceptions\Curl\CouldNotResolveHostException;
 use OpenSearch\Common\Exceptions\Curl\OperationTimeoutException;
-use OpenSearch\Common\Exceptions\OpenSearchException;
 use OpenSearch\Common\Exceptions\Forbidden403Exception;
 use OpenSearch\Common\Exceptions\MaxRetriesException;
 use OpenSearch\Common\Exceptions\Missing404Exception;
 use OpenSearch\Common\Exceptions\NoDocumentsToGetException;
 use OpenSearch\Common\Exceptions\NoShardAvailableException;
+use OpenSearch\Common\Exceptions\OpenSearchException;
 use OpenSearch\Common\Exceptions\RequestTimeout408Exception;
 use OpenSearch\Common\Exceptions\RoutingMissingException;
 use OpenSearch\Common\Exceptions\ScriptLangNotSupportedException;
@@ -41,12 +45,13 @@
 use OpenSearch\Common\Exceptions\Unauthorized401Exception;
 use OpenSearch\Serializers\SerializerInterface;
 use OpenSearch\Transport;
-use Exception;
-use GuzzleHttp\Ring\Core;
-use GuzzleHttp\Ring\Exception\ConnectException;
-use GuzzleHttp\Ring\Exception\RingException;
 use Psr\Log\LoggerInterface;
 
+@trigger_error(Connection::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 class Connection implements ConnectionInterface
 {
     /**
diff --git a/src/OpenSearch/Connections/ConnectionFactory.php b/src/OpenSearch/Connections/ConnectionFactory.php
index f95c2f29..f19d78b4 100644
--- a/src/OpenSearch/Connections/ConnectionFactory.php
+++ b/src/OpenSearch/Connections/ConnectionFactory.php
@@ -24,6 +24,11 @@
 use OpenSearch\Serializers\SerializerInterface;
 use Psr\Log\LoggerInterface;
 
+@trigger_error(ConnectionFactory::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 class ConnectionFactory implements ConnectionFactoryInterface
 {
     /**
diff --git a/src/OpenSearch/Connections/ConnectionFactoryInterface.php b/src/OpenSearch/Connections/ConnectionFactoryInterface.php
index da209abd..ddb240cd 100644
--- a/src/OpenSearch/Connections/ConnectionFactoryInterface.php
+++ b/src/OpenSearch/Connections/ConnectionFactoryInterface.php
@@ -21,6 +21,11 @@
 
 namespace OpenSearch\Connections;
 
+@trigger_error(ConnectionFactoryInterface::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 interface ConnectionFactoryInterface
 {
     /**
diff --git a/src/OpenSearch/Connections/ConnectionInterface.php b/src/OpenSearch/Connections/ConnectionInterface.php
index 0e6280ae..791c5a79 100644
--- a/src/OpenSearch/Connections/ConnectionInterface.php
+++ b/src/OpenSearch/Connections/ConnectionInterface.php
@@ -21,10 +21,13 @@
 
 namespace OpenSearch\Connections;
 
-use OpenSearch\Serializers\SerializerInterface;
 use OpenSearch\Transport;
-use Psr\Log\LoggerInterface;
 
+@trigger_error(ConnectionInterface::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 interface ConnectionInterface
 {
     /**
diff --git a/src/OpenSearch/EndpointFactory.php b/src/OpenSearch/EndpointFactory.php
index 65bb5b36..61abbe25 100644
--- a/src/OpenSearch/EndpointFactory.php
+++ b/src/OpenSearch/EndpointFactory.php
@@ -4,6 +4,7 @@
 
 use OpenSearch\Endpoints\AbstractEndpoint;
 use OpenSearch\Serializers\SerializerInterface;
+use OpenSearch\Serializers\SmartSerializer;
 use ReflectionClass;
 
 /**
@@ -16,9 +17,11 @@ class EndpointFactory implements EndpointFactoryInterface
      */
     private array $endpoints = [];
 
-    public function __construct(
-        protected SerializerInterface $serializer,
-    ) {
+    private ?SerializerInterface $serializer;
+
+    public function __construct(?SerializerInterface $serializer = null)
+    {
+        $this->serializer = $serializer;
     }
 
     /**
@@ -33,6 +36,14 @@ public function getEndpoint(string $class): AbstractEndpoint
         return $this->endpoints[$class];
     }
 
+    private function getSerializer(): SerializerInterface
+    {
+        if ($this->serializer === null) {
+            $this->serializer = new SmartSerializer();
+        }
+        return $this->serializer;
+    }
+
     /**
      * Creates an endpoint.
      *
@@ -47,7 +58,7 @@ private function createEndpoint(string $class): AbstractEndpoint
         $constructor = $reflection->getConstructor();
 
         if ($constructor && $constructor->getParameters()) {
-            return new $class($this->serializer);
+            return new $class($this->getSerializer());
         }
         return new $class();
     }
diff --git a/src/OpenSearch/EndpointInterface.php b/src/OpenSearch/EndpointInterface.php
index c28c63ef..f29783df 100644
--- a/src/OpenSearch/EndpointInterface.php
+++ b/src/OpenSearch/EndpointInterface.php
@@ -66,16 +66,14 @@ public function setId(int|string|null $docID): static;
 
     /**
      * Get the body of the request.
-     *
-     * @return array|string
      */
-    public function getBody(): array|string;
+    public function getBody(): string|array|null;
 
     /**
      * Set the body of the request.
      *
-     * @param array<string,mixed> $body
+     * @param string|iterable<string,mixed>|null $body
      */
-    public function setBody(array $body): static;
+    public function setBody(string|iterable|null $body): static;
 
 }
diff --git a/src/OpenSearch/Endpoints/AbstractEndpoint.php b/src/OpenSearch/Endpoints/AbstractEndpoint.php
index 0b049dae..31c19c09 100644
--- a/src/OpenSearch/Endpoints/AbstractEndpoint.php
+++ b/src/OpenSearch/Endpoints/AbstractEndpoint.php
@@ -22,11 +22,12 @@
 namespace OpenSearch\Endpoints;
 
 use OpenSearch\Common\Exceptions\UnexpectedValueException;
+use OpenSearch\EndpointInterface;
 use OpenSearch\Serializers\SerializerInterface;
 
 use function array_filter;
 
-abstract class AbstractEndpoint
+abstract class AbstractEndpoint implements EndpointInterface
 {
     /**
      * @var array
@@ -85,7 +86,7 @@ abstract public function getMethod(): string;
      * @param mixed[] $params Array of parameters
      * @return $this
      */
-    public function setParams(array $params)
+    public function setParams(array $params): static
     {
         $this->extractOptions($params);
         $this->checkUserParams($params);
@@ -117,7 +118,7 @@ public function getIndex(): ?string
      *
      * @return $this
      */
-    public function setIndex($index)
+    public function setIndex($index): static
     {
         if ($index === null) {
             return $this;
@@ -134,12 +135,7 @@ public function setIndex($index)
         return $this;
     }
 
-    /**
-     * @param int|string|null $docID
-     *
-     * @return $this
-     */
-    public function setId($docID)
+    public function setId(int|string|null $docID): static
     {
         if ($docID === null) {
             return $this;
@@ -154,16 +150,12 @@ public function setId($docID)
         return $this;
     }
 
-    /**
-     * @return array|string
-     */
-    public function getBody()
+    public function getBody(): string|array|null
     {
         return $this->body;
     }
 
-
-    public function setBody(array $body)
+    public function setBody(string|iterable|null $body): static
     {
         $this->body = $body;
 
diff --git a/src/OpenSearch/Endpoints/AsyncSearch/Submit.php b/src/OpenSearch/Endpoints/AsyncSearch/Submit.php
index d10e801b..21edf79a 100644
--- a/src/OpenSearch/Endpoints/AsyncSearch/Submit.php
+++ b/src/OpenSearch/Endpoints/AsyncSearch/Submit.php
@@ -87,7 +87,7 @@ public function getMethod(): string
         return 'POST';
     }
 
-    public function setBody($body): Submit
+    public function setBody($body): static
     {
         if (isset($body) !== true) {
             return $this;
diff --git a/src/OpenSearch/Endpoints/DataFrameTransformDeprecated/PreviewTransform.php b/src/OpenSearch/Endpoints/DataFrameTransformDeprecated/PreviewTransform.php
index e2db220a..3f949ea1 100644
--- a/src/OpenSearch/Endpoints/DataFrameTransformDeprecated/PreviewTransform.php
+++ b/src/OpenSearch/Endpoints/DataFrameTransformDeprecated/PreviewTransform.php
@@ -40,7 +40,7 @@ public function getMethod(): string
         return 'POST';
     }
 
-    public function setBody($body): PreviewTransform
+    public function setBody($body): static
     {
         if (isset($body) !== true) {
             return $this;
diff --git a/src/OpenSearch/Endpoints/DataFrameTransformDeprecated/PutTransform.php b/src/OpenSearch/Endpoints/DataFrameTransformDeprecated/PutTransform.php
index ca259759..675dcced 100644
--- a/src/OpenSearch/Endpoints/DataFrameTransformDeprecated/PutTransform.php
+++ b/src/OpenSearch/Endpoints/DataFrameTransformDeprecated/PutTransform.php
@@ -50,7 +50,7 @@ public function getMethod(): string
         return 'PUT';
     }
 
-    public function setBody($body): PutTransform
+    public function setBody($body): static
     {
         if (isset($body) !== true) {
             return $this;
diff --git a/src/OpenSearch/Endpoints/DataFrameTransformDeprecated/UpdateTransform.php b/src/OpenSearch/Endpoints/DataFrameTransformDeprecated/UpdateTransform.php
index 30b3dd2d..b5d6f13f 100644
--- a/src/OpenSearch/Endpoints/DataFrameTransformDeprecated/UpdateTransform.php
+++ b/src/OpenSearch/Endpoints/DataFrameTransformDeprecated/UpdateTransform.php
@@ -50,7 +50,7 @@ public function getMethod(): string
         return 'POST';
     }
 
-    public function setBody($body): UpdateTransform
+    public function setBody($body): static
     {
         if (isset($body) !== true) {
             return $this;
@@ -60,7 +60,7 @@ public function setBody($body): UpdateTransform
         return $this;
     }
 
-    public function setTransformId($transform_id): UpdateTransform
+    public function setTransformId($transform_id): static
     {
         if (isset($transform_id) !== true) {
             return $this;
diff --git a/src/OpenSearch/Endpoints/Monitoring/Bulk.php b/src/OpenSearch/Endpoints/Monitoring/Bulk.php
index a40ffdab..797a3f6b 100644
--- a/src/OpenSearch/Endpoints/Monitoring/Bulk.php
+++ b/src/OpenSearch/Endpoints/Monitoring/Bulk.php
@@ -52,7 +52,7 @@ public function getMethod(): string
         return 'POST';
     }
 
-    public function setBody($body): Bulk
+    public function setBody($body): static
     {
         if (isset($body) !== true) {
             return $this;
diff --git a/src/OpenSearch/Endpoints/SearchableSnapshots/Mount.php b/src/OpenSearch/Endpoints/SearchableSnapshots/Mount.php
index 3f51d266..af223c10 100644
--- a/src/OpenSearch/Endpoints/SearchableSnapshots/Mount.php
+++ b/src/OpenSearch/Endpoints/SearchableSnapshots/Mount.php
@@ -54,7 +54,7 @@ public function getMethod(): string
         return 'POST';
     }
 
-    public function setBody($body): Mount
+    public function setBody($body): static
     {
         if (isset($body) !== true) {
             return $this;
@@ -64,7 +64,7 @@ public function setBody($body): Mount
         return $this;
     }
 
-    public function setRepository($repository): Mount
+    public function setRepository($repository): static
     {
         if (isset($repository) !== true) {
             return $this;
@@ -74,7 +74,7 @@ public function setRepository($repository): Mount
         return $this;
     }
 
-    public function setSnapshot($snapshot): Mount
+    public function setSnapshot($snapshot): static
     {
         if (isset($snapshot) !== true) {
             return $this;
diff --git a/src/OpenSearch/Handlers/SigV4Handler.php b/src/OpenSearch/Handlers/SigV4Handler.php
index e45639c7..fa1edad1 100644
--- a/src/OpenSearch/Handlers/SigV4Handler.php
+++ b/src/OpenSearch/Handlers/SigV4Handler.php
@@ -13,8 +13,12 @@
 use Psr\Http\Message\RequestInterface;
 use RuntimeException;
 
+@trigger_error(SigV4Handler::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
 /**
  * @phpstan-type RingPhpRequest array{http_method: string, scheme: string, uri: string, query_string?: string, version?: string, headers: array<string, list<string>>, body: string|resource|null, client?: array<string, mixed>}
+ *
+ * @deprecated in 2.3.2 and will be removed in 3.0.0. Use \OpenSearch\Aws\SigV4RequestFactory instead.
  */
 class SigV4Handler
 {
diff --git a/src/OpenSearch/HttpTransport.php b/src/OpenSearch/HttpTransport.php
new file mode 100644
index 00000000..c7c4608e
--- /dev/null
+++ b/src/OpenSearch/HttpTransport.php
@@ -0,0 +1,44 @@
+<?php
+
+namespace OpenSearch;
+
+use OpenSearch\Serializers\SerializerInterface;
+use Psr\Http\Client\ClientInterface;
+use Psr\Http\Message\RequestInterface;
+
+/**
+ * Transport that uses PSR-7, PSR-17 and PSR-18 interfaces.
+ */
+final class HttpTransport implements TransportInterface
+{
+    public function __construct(
+        protected ClientInterface $client,
+        protected RequestFactoryInterface $requestFactory,
+        protected SerializerInterface $serializer,
+    ) {
+    }
+
+    /**
+     * Create a new request.
+     */
+    public function createRequest(string $method, string $uri, array $params = [], mixed $body = null, array $headers = []): RequestInterface
+    {
+        return $this->requestFactory->createRequest($method, $uri, $params, $body, $headers);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function sendRequest(
+        string $method,
+        string $uri,
+        array $params = [],
+        mixed $body = null,
+        array $headers = [],
+    ): array|string|null {
+        $request = $this->createRequest($method, $uri, $params, $body, $headers);
+        $response = $this->client->sendRequest($request);
+        return $this->serializer->deserialize($response->getBody()->getContents(), $response->getHeaders());
+    }
+
+}
diff --git a/src/OpenSearch/LegacyTransportWrapper.php b/src/OpenSearch/LegacyTransportWrapper.php
new file mode 100644
index 00000000..9b058216
--- /dev/null
+++ b/src/OpenSearch/LegacyTransportWrapper.php
@@ -0,0 +1,37 @@
+<?php
+
+namespace OpenSearch;
+
+use GuzzleHttp\Ring\Future\FutureArrayInterface;
+
+/**
+ * Transport that wraps the legacy transport.
+ *
+ * @deprecated in 2.3.2 and will be removed in 3.0.0. Use PsrTransport instead.
+ */
+class LegacyTransportWrapper implements TransportInterface
+{
+    public function __construct(
+        protected Transport $transport,
+    ) {
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function sendRequest(
+        string $method,
+        string $uri,
+        array $params = [],
+        mixed $body = null,
+        array $headers = [],
+    ): array|string|null {
+        $promise = $this->transport->performRequest($method, $uri, $params, $body);
+        $futureArray = $this->transport->resultOrFuture($promise);
+        if ($futureArray instanceof FutureArrayInterface) {
+            return $futureArray->wait();
+        }
+        return $futureArray;
+    }
+
+}
diff --git a/src/OpenSearch/Namespaces/AbstractNamespace.php b/src/OpenSearch/Namespaces/AbstractNamespace.php
index ec908dca..d11b66ef 100644
--- a/src/OpenSearch/Namespaces/AbstractNamespace.php
+++ b/src/OpenSearch/Namespaces/AbstractNamespace.php
@@ -24,15 +24,21 @@
 use OpenSearch\EndpointFactoryInterface;
 use OpenSearch\Endpoints\AbstractEndpoint;
 use OpenSearch\LegacyEndpointFactory;
+use OpenSearch\LegacyTransportWrapper;
 use OpenSearch\Transport;
+use OpenSearch\TransportInterface;
 
 abstract class AbstractNamespace
 {
     /**
      * @var \OpenSearch\Transport
+     *
+     * @deprecated in 2.3.2 and will be removed in 3.0.0. Use $httpTransport property instead.
      */
     protected $transport;
 
+    protected TransportInterface $httpTransport;
+
     protected EndpointFactoryInterface $endpointFactory;
 
     /**
@@ -42,9 +48,15 @@ abstract class AbstractNamespace
      */
     protected $endpoints;
 
-    public function __construct(Transport $transport, callable|EndpointFactoryInterface $endpointFactory)
+    public function __construct(TransportInterface|Transport $transport, callable|EndpointFactoryInterface $endpointFactory)
     {
-        $this->transport = $transport;
+        if (!$transport instanceof TransportInterface) {
+            @trigger_error('Passing an instance of \OpenSearch\Transport to ' . __METHOD__ . '() is deprecated in 2.3.2 and will be removed in 3.0.0. Pass an instance of \OpenSearch\TransportInterface instead.', E_USER_DEPRECATED);
+            $this->transport = $transport;
+            $this->httpTransport = new LegacyTransportWrapper($transport);
+        } else {
+            $this->httpTransport = $transport;
+        }
         if (is_callable($endpointFactory)) {
             @trigger_error('Passing a callable as $endpointFactory param to ' . __METHOD__ . '() is deprecated in 2.3.2 and will be removed in 3.0.0. Pass an instance of \OpenSearch\EndpointFactoryInterface instead.', E_USER_DEPRECATED);
             $endpoints = $endpointFactory;
@@ -75,7 +87,7 @@ public function extractArgument(array &$params, string $arg)
 
     protected function performRequest(AbstractEndpoint $endpoint)
     {
-        $response = $this->transport->performRequest(
+        return $this->httpTransport->sendRequest(
             $endpoint->getMethod(),
             $endpoint->getURI(),
             $endpoint->getParams(),
@@ -83,6 +95,5 @@ protected function performRequest(AbstractEndpoint $endpoint)
             $endpoint->getOptions()
         );
 
-        return $this->transport->resultOrFuture($response, $endpoint->getOptions());
     }
 }
diff --git a/src/OpenSearch/Namespaces/BooleanRequestWrapper.php b/src/OpenSearch/Namespaces/BooleanRequestWrapper.php
index 9c29f656..1e6f55b5 100644
--- a/src/OpenSearch/Namespaces/BooleanRequestWrapper.php
+++ b/src/OpenSearch/Namespaces/BooleanRequestWrapper.php
@@ -26,17 +26,51 @@
 use OpenSearch\Endpoints\AbstractEndpoint;
 use OpenSearch\Transport;
 use GuzzleHttp\Ring\Future\FutureArrayInterface;
+use OpenSearch\TransportInterface;
+use Psr\Http\Client\ClientExceptionInterface;
 
 abstract class BooleanRequestWrapper
 {
+    /**
+     * Send a request with a boolean response.
+     *
+     * @return bool
+     *   Returns FALSE for a 404 error, otherwise TRUE.
+     *
+     * @throws \Psr\Http\Client\ClientExceptionInterface
+     */
+    public static function sendRequest(AbstractEndpoint $endpoint, TransportInterface $transport): bool
+    {
+        try {
+            $transport->sendRequest(
+                $endpoint->getMethod(),
+                $endpoint->getURI(),
+                $endpoint->getParams(),
+                $endpoint->getBody(),
+                $endpoint->getOptions()
+            );
+        } catch (ClientExceptionInterface $e) {
+            if ($e->getCode() === 404) {
+                return false;
+            }
+            throw $e;
+        }
+        return true;
+    }
+
     /**
      * Perform Request
      *
      * @throws Missing404Exception
      * @throws RoutingMissingException
+     *
+     * @deprecated in 2.3.2 and will be removed in 3.0.0. Use \OpenSearch\Namespaces\BooleanRequestWrapper::sendRequest() instead.
      */
     public static function performRequest(AbstractEndpoint $endpoint, Transport $transport)
     {
+        @trigger_error(
+            __METHOD__ . '() is deprecated in 2.3.2 and will be removed in 3.0.0. Use \OpenSearch\Namespaces\BooleanRequestWrapper::sendRequest() instead.'
+        );
         try {
             $response = $transport->performRequest(
                 $endpoint->getMethod(),
diff --git a/src/OpenSearch/Namespaces/ClusterNamespace.php b/src/OpenSearch/Namespaces/ClusterNamespace.php
index 7d763a50..3ebcd0f8 100644
--- a/src/OpenSearch/Namespaces/ClusterNamespace.php
+++ b/src/OpenSearch/Namespaces/ClusterNamespace.php
@@ -174,7 +174,7 @@ public function existsComponentTemplate(array $params = []): bool
         $endpoint->setParams($params);
         $endpoint->setName($name);
 
-        return BooleanRequestWrapper::performRequest($endpoint, $this->transport);
+        return BooleanRequestWrapper::sendRequest($endpoint, $this->httpTransport);
     }
 
     /**
diff --git a/src/OpenSearch/RequestFactory.php b/src/OpenSearch/RequestFactory.php
new file mode 100644
index 00000000..e0729b97
--- /dev/null
+++ b/src/OpenSearch/RequestFactory.php
@@ -0,0 +1,48 @@
+<?php
+
+namespace OpenSearch;
+
+use OpenSearch\Serializers\SerializerInterface;
+use Psr\Http\Message\RequestFactoryInterface as PsrRequestFactoryInterface;
+use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\StreamFactoryInterface;
+use Psr\Http\Message\UriFactoryInterface;
+
+/**
+ * Request factory that uses PSR-7, PSR-17 and PSR-18 interfaces.
+ */
+final class RequestFactory implements RequestFactoryInterface
+{
+    public function __construct(
+        protected PsrRequestFactoryInterface $psrRequestFactory,
+        protected StreamFactoryInterface $streamFactory,
+        protected UriFactoryInterface $uriFactory,
+        protected SerializerInterface $serializer,
+    ) {
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function createRequest(
+        string $method,
+        string $uri,
+        array $params = [],
+        string|array|null $body = null,
+        array $headers = [],
+    ): RequestInterface {
+        $uri = $this->uriFactory->createUri($uri);
+        $uri = $uri->withQuery(http_build_query($params));
+        $request = $this->psrRequestFactory->createRequest($method, $uri);
+        if ($body !== null) {
+            $bodyJson = $this->serializer->serialize($body);
+            $bodyStream = $this->streamFactory->createStream($bodyJson);
+            $request = $request->withBody($bodyStream);
+        }
+        foreach ($headers as $name => $value) {
+            $request = $request->withHeader($name, $value);
+        }
+        return $request;
+    }
+
+}
diff --git a/src/OpenSearch/RequestFactoryInterface.php b/src/OpenSearch/RequestFactoryInterface.php
new file mode 100644
index 00000000..46562496
--- /dev/null
+++ b/src/OpenSearch/RequestFactoryInterface.php
@@ -0,0 +1,23 @@
+<?php
+
+namespace OpenSearch;
+
+use Psr\Http\Message\RequestInterface;
+
+interface RequestFactoryInterface
+{
+    /**
+     * Create a new request.
+     *
+     * @param array<string, mixed> $params
+     * @param string|array<string, mixed>|null $body
+     * @param array<string, string> $headers
+     */
+    public function createRequest(
+        string $method,
+        string $uri,
+        array $params = [],
+        string|array|null $body = null,
+        array $headers = [],
+    ): RequestInterface;
+}
diff --git a/src/OpenSearch/Transport.php b/src/OpenSearch/Transport.php
index df6b5b98..cd4ecf07 100644
--- a/src/OpenSearch/Transport.php
+++ b/src/OpenSearch/Transport.php
@@ -21,13 +21,17 @@
 
 namespace OpenSearch;
 
+use GuzzleHttp\Ring\Future\FutureArrayInterface;
 use OpenSearch\Common\Exceptions;
 use OpenSearch\ConnectionPool\AbstractConnectionPool;
-use OpenSearch\Connections\Connection;
 use OpenSearch\Connections\ConnectionInterface;
-use GuzzleHttp\Ring\Future\FutureArrayInterface;
 use Psr\Log\LoggerInterface;
 
+@trigger_error(Transport::class . ' is deprecated in 2.3.2 and will be removed in 3.0.0.', E_USER_DEPRECATED);
+
+/**
+ * @deprecated in 2.3.2 and will be removed in 3.0.0.
+ */
 class Transport
 {
     /**
diff --git a/src/OpenSearch/TransportFactory.php b/src/OpenSearch/TransportFactory.php
new file mode 100644
index 00000000..c137a867
--- /dev/null
+++ b/src/OpenSearch/TransportFactory.php
@@ -0,0 +1,134 @@
+<?php
+
+namespace OpenSearch;
+
+use Http\Discovery\Psr17FactoryDiscovery;
+use Http\Discovery\Psr18ClientDiscovery;
+use OpenSearch\Serializers\SerializerInterface;
+use OpenSearch\Serializers\SmartSerializer;
+use Psr\Http\Client\ClientInterface;
+use Psr\Http\Message\RequestFactoryInterface as PsrRequestFactoryInterface;
+use Psr\Http\Message\StreamFactoryInterface;
+use Psr\Http\Message\UriFactoryInterface;
+
+/**
+ * Creates a PSR transport falling back to a discovery mechanism if properties are not specified.
+ */
+class TransportFactory
+{
+    private ?PsrRequestFactoryInterface $psrRequestFactory = null;
+
+    private ?StreamFactoryInterface $streamFactory = null;
+
+    private ?UriFactoryInterface $uriFactory = null;
+
+    private ?SerializerInterface $serializer = null;
+
+    private ?RequestFactoryInterface $requestFactory = null;
+
+    private ?ClientInterface $httpClient = null;
+
+    protected function getHttpClient(): ?ClientInterface
+    {
+        return $this->httpClient;
+    }
+
+    public function setHttpClient(?ClientInterface $httpClient): static
+    {
+        $this->httpClient = $httpClient;
+        return $this;
+    }
+
+    protected function getRequestFactory(): ?RequestFactoryInterface
+    {
+        return $this->requestFactory;
+    }
+
+    public function setRequestFactory(?RequestFactoryInterface $requestFactory): static
+    {
+        $this->requestFactory = $requestFactory;
+        return $this;
+    }
+
+    protected function getPsrRequestFactory(): PsrRequestFactoryInterface
+    {
+        if ($this->psrRequestFactory === null) {
+            $this->psrRequestFactory = Psr17FactoryDiscovery::findRequestFactory();
+        }
+        return $this->psrRequestFactory;
+    }
+
+    public function setPsrRequestFactory(PsrRequestFactoryInterface $psrRequestFactory): static
+    {
+        $this->psrRequestFactory = $psrRequestFactory;
+        return $this;
+    }
+
+    protected function getStreamFactory(): StreamFactoryInterface
+    {
+        if ($this->streamFactory === null) {
+            $this->streamFactory = Psr17FactoryDiscovery::findStreamFactory();
+        }
+        return $this->streamFactory;
+    }
+
+    public function setStreamFactory(StreamFactoryInterface $streamFactory): static
+    {
+        $this->streamFactory = $streamFactory;
+        return $this;
+    }
+
+    protected function getUriFactory(): UriFactoryInterface
+    {
+        if ($this->uriFactory === null) {
+            $this->uriFactory = Psr17FactoryDiscovery::findUriFactory();
+        }
+        return $this->uriFactory;
+    }
+
+    public function setUriFactory(UriFactoryInterface $uriFactory): static
+    {
+        $this->uriFactory = $uriFactory;
+        return $this;
+    }
+
+    protected function getSerializer(): Serializers\SerializerInterface
+    {
+        if ($this->serializer === null) {
+            $this->serializer = new SmartSerializer();
+        }
+        return $this->serializer;
+    }
+
+    public function setSerializer(Serializers\SerializerInterface $serializer): static
+    {
+        $this->serializer = $serializer;
+        return $this;
+    }
+
+    /**
+     * Creates a new transport.
+     */
+    public function create(): HttpTransport
+    {
+        if ($this->requestFactory === null) {
+            $psrRequestFactory = $this->getPsrRequestFactory();
+            $streamFactory = $this->getStreamFactory();
+            $uriFactory = $this->getUriFactory();
+            $serializer = $this->getSerializer();
+
+            $this->requestFactory = new RequestFactory(
+                $psrRequestFactory,
+                $streamFactory,
+                $uriFactory,
+                $serializer
+            );
+        }
+        if ($this->httpClient === null) {
+            $this->httpClient = Psr18ClientDiscovery::find();
+        }
+
+        return new HttpTransport($this->httpClient, $this->requestFactory, $this->getSerializer());
+    }
+
+}
diff --git a/src/OpenSearch/TransportInterface.php b/src/OpenSearch/TransportInterface.php
new file mode 100644
index 00000000..5346fee0
--- /dev/null
+++ b/src/OpenSearch/TransportInterface.php
@@ -0,0 +1,27 @@
+<?php
+
+namespace OpenSearch;
+
+/**
+ * Provides an interface for sending OpenSearch requests.
+ */
+interface TransportInterface
+{
+    /**
+     * Create a new request.
+     *
+     * @param array<string, mixed> $params
+     * @param string|array<string, mixed>|null $body
+     * @param array<string, string> $headers
+     *
+     * @throws \Psr\Http\Client\ClientExceptionInterface
+     */
+    public function sendRequest(
+        string $method,
+        string $uri,
+        array $params = [],
+        string|array|null $body = null,
+        array $headers = [],
+    ): array|string|null;
+
+}
diff --git a/tests/ClientTest.php b/tests/ClientTest.php
index b580bae5..ce5a2bc7 100644
--- a/tests/ClientTest.php
+++ b/tests/ClientTest.php
@@ -21,443 +21,108 @@
 
 namespace OpenSearch\Tests;
 
-use GuzzleHttp\Ring\Client\MockHandler;
-use GuzzleHttp\Ring\Future\FutureArray;
-use Mockery as m;
-use OpenSearch;
 use OpenSearch\Client;
-use OpenSearch\ClientBuilder;
-use OpenSearch\Common\Exceptions\MaxRetriesException;
+use OpenSearch\Common\Exceptions\RuntimeException;
+use OpenSearch\EndpointFactoryInterface;
+use OpenSearch\Endpoints\Delete;
+use OpenSearch\Transport;
+use OpenSearch\TransportInterface;
+use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
+use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\ResponseInterface;
 
 /**
  * Class ClientTest
  *
  * @subpackage Tests
+ * @coversDefaultClass \OpenSearch\Client
  */
-class ClientTest extends \PHPUnit\Framework\TestCase
+class ClientTest extends TestCase
 {
-    public function tearDown(): void
-    {
-        m::close();
-    }
+    /**
+     * The client under test.
+     */
+    private Client $client;
 
-    public function testConstructorIllegalPort()
-    {
-        $this->expectException(\OpenSearch\Common\Exceptions\InvalidArgumentException::class);
-        $this->expectExceptionMessage('Could not parse URI');
+    private EndpointFactoryInterface|MockObject $endpointFactory;
 
-        $client = OpenSearch\ClientBuilder::create()->setHosts(['localhost:abc'])->build();
-    }
+    private TransportInterface|MockObject $transport;
 
-    public function testFromConfig()
+    /**
+     * {@inheritdoc}
+     */
+    public function setUp(): void
     {
-        $params = [
-            'hosts' => [
-                'localhost:9200'
-            ],
-            'retries' => 2,
-            'handler' => ClientBuilder::multiHandler()
-        ];
-        $client = ClientBuilder::fromConfig($params);
-
-        $this->assertInstanceOf(Client::class, $client);
+        parent::setUp();
+        $this->transport = $this->createMock(TransportInterface::class);
+        $this->endpointFactory = $this->createMock(EndpointFactoryInterface::class);
+        $registeredNamespaces = [];
+        $this->client = new Client($this->transport, $this->endpointFactory, $registeredNamespaces);
     }
 
-    public function testFromConfigBadParam()
+    /**
+     * @covers ::__call
+     */
+    public function testUnknownNamespace(): void
     {
-        $params = [
-            'hosts' => [
-                'localhost:9200'
-            ],
-            'retries' => 2,
-            'imNotReal' => 5
-        ];
-
-        $this->expectException(\OpenSearch\Common\Exceptions\RuntimeException::class);
-        $this->expectExceptionMessage('Unknown parameters provided: imNotReal');
-
-        $client = ClientBuilder::fromConfig($params);
+        $this->expectException(\BadMethodCallException::class);
+        $this->client->foo();
     }
 
-    public function testFromConfigBadParamQuiet()
-    {
-        $params = [
-            'hosts' => [
-                'localhost:9200'
-            ],
-            'retries' => 2,
-            'imNotReal' => 5
-        ];
-        $client = ClientBuilder::fromConfig($params, true);
-
-        $this->assertInstanceOf(Client::class, $client);
-    }
 
     public function testIndexCannotBeNullForDelete()
     {
-        $client = ClientBuilder::create()->build();
+        $this->endpointFactory->expects($this->once())
+            ->method('getEndpoint')
+            ->with(Delete::class)
+            ->willReturn(new Delete());
 
-        $this->expectException(OpenSearch\Common\Exceptions\RuntimeException::class);
+        $this->expectException(RuntimeException::class);
         $this->expectExceptionMessage('index is required for delete');
 
-        $client->delete(
+        $this->client->delete(
             [
-            'index' => null,
-            'id' => 'test'
+                'index' => null,
+                'id' => 'test'
             ]
         );
     }
 
     public function testIdCannotBeNullForDelete()
     {
-        $client = ClientBuilder::create()->build();
+        $this->endpointFactory->expects($this->once())
+            ->method('getEndpoint')
+            ->with(Delete::class)
+            ->willReturn(new Delete());
 
-        $this->expectException(OpenSearch\Common\Exceptions\RuntimeException::class);
+        $this->expectException(RuntimeException::class);
         $this->expectExceptionMessage('id is required for delete');
 
-        $client->delete(
+        $this->client->delete(
             [
-            'index' => 'test',
-            'id' => null
+                'index' => 'test',
+                'id' => null
             ]
         );
     }
 
-    public function testMaxRetriesException()
+    /**
+     * @covers ::request
+     */
+    public function testSendRawRequest(): void
     {
-        $client = OpenSearch\ClientBuilder::create()
-            ->setHosts(["localhost:1"])
-            ->setRetries(0)
-            ->build();
-
-        $searchParams = [
-            'index' => 'test',
-            'body' => [
-                'query' => [
-                    'match_all' => []
-                ]
-            ]
-        ];
-
-        $client = OpenSearch\ClientBuilder::create()
-            ->setHosts(["localhost:1"])
-            ->setRetries(0)
-            ->build();
-
-        try {
-            $client->search($searchParams);
-            $this->fail("Should have thrown CouldNotConnectToHost");
-        } catch (OpenSearch\Common\Exceptions\Curl\CouldNotConnectToHost $e) {
-            // All good
-            $previous = $e->getPrevious();
-            $this->assertInstanceOf(MaxRetriesException::class, $previous);
-        } catch (\Exception $e) {
-            throw $e;
-        }
-
-
-        $client = OpenSearch\ClientBuilder::create()
-            ->setHosts(["localhost:1"])
-            ->setRetries(0)
-            ->build();
-
-        try {
-            $client->search($searchParams);
-            $this->fail("Should have thrown TransportException");
-        } catch (OpenSearch\Common\Exceptions\TransportException $e) {
-            // All good
-            $previous = $e->getPrevious();
-            $this->assertInstanceOf(MaxRetriesException::class, $previous);
-        } catch (\Exception $e) {
-            throw $e;
-        }
-    }
-
-    public function testInlineHosts()
-    {
-        $client = OpenSearch\ClientBuilder::create()->setHosts(
-            [
-            'localhost:9200'
-            ]
-        )->build();
-        $host = $client->transport->getConnection();
-        $this->assertSame("localhost", $host->getHost());
-        $this->assertSame(9200, $host->getPort());
-        $this->assertSame("http", $host->getTransportSchema());
-
-
-        $client = OpenSearch\ClientBuilder::create()->setHosts(
-            [
-            'http://localhost:9200'
-            ]
-        )->build();
-        $host = $client->transport->getConnection();
-        $this->assertSame("localhost", $host->getHost());
-        $this->assertSame(9200, $host->getPort());
-        $this->assertSame("http", $host->getTransportSchema());
-
-        $client = OpenSearch\ClientBuilder::create()->setHosts(
-            [
-            'http://foo.com:9200'
-            ]
-        )->build();
-        $host = $client->transport->getConnection();
-        $this->assertSame("foo.com", $host->getHost());
-        $this->assertSame(9200, $host->getPort());
-        $this->assertSame("http", $host->getTransportSchema());
-
-        $client = OpenSearch\ClientBuilder::create()->setHosts(
-            [
-            'https://foo.com:9200'
-            ]
-        )->build();
-        $host = $client->transport->getConnection();
-        $this->assertSame("foo.com", $host->getHost());
-        $this->assertSame(9200, $host->getPort());
-        $this->assertSame("https", $host->getTransportSchema());
-
-
-        $client = OpenSearch\ClientBuilder::create()->setHosts(
-            [
-            'https://user:pass@foo.com:9200'
-            ]
-        )->build();
-        $host = $client->transport->getConnection();
-        $this->assertSame("foo.com", $host->getHost());
-        $this->assertSame(9200, $host->getPort());
-        $this->assertSame("https", $host->getTransportSchema());
-        $this->assertSame("user:pass", $host->getUserPass());
-
-        $client = OpenSearch\ClientBuilder::create()->setHosts(
-            [
-            'https://user:pass@the_foo.com:9200'
-            ]
-        )->build();
-        $host = $client->transport->getConnection();
-        $this->assertSame("the_foo.com", $host->getHost());
-        $this->assertSame(9200, $host->getPort());
-        $this->assertSame("https", $host->getTransportSchema());
-        $this->assertSame("user:pass", $host->getUserPass());
-    }
-
-    public function testExtendedHosts()
-    {
-        $client = OpenSearch\ClientBuilder::create()->setHosts(
-            [
-            [
-                'host' => 'localhost',
-                'port' => 9200,
-                'scheme' => 'http'
-            ]
-            ]
-        )->build();
-        $host = $client->transport->getConnection();
-        $this->assertSame("localhost", $host->getHost());
-        $this->assertSame(9200, $host->getPort());
-        $this->assertSame("http", $host->getTransportSchema());
-
-
-        $client = OpenSearch\ClientBuilder::create()->setHosts(
-            [
-            [
-                'host' => 'foo.com',
-                'port' => 9200,
-                'scheme' => 'http'
-            ]
-            ]
-        )->build();
-        $host = $client->transport->getConnection();
-        $this->assertSame("foo.com", $host->getHost());
-        $this->assertSame(9200, $host->getPort());
-        $this->assertSame("http", $host->getTransportSchema());
-
-
-        $client = OpenSearch\ClientBuilder::create()->setHosts(
-            [
-            [
-                'host' => 'foo.com',
-                'port' => 9200,
-                'scheme' => 'https'
-            ]
-            ]
-        )->build();
-        $host = $client->transport->getConnection();
-        $this->assertSame("foo.com", $host->getHost());
-        $this->assertSame(9200, $host->getPort());
-        $this->assertSame("https", $host->getTransportSchema());
-
-
-        $client = OpenSearch\ClientBuilder::create()->setHosts(
-            [
-            [
-                'host' => 'foo.com',
-                'scheme' => 'http'
-            ]
-            ]
-        )->build();
-        $host = $client->transport->getConnection();
-        $this->assertSame("foo.com", $host->getHost());
-        $this->assertSame(9200, $host->getPort());
-        $this->assertSame("http", $host->getTransportSchema());
-
+        $this->transport->expects($this->once())
+            ->method('sendRequest')
+            ->with('GET', '/', ['foo' => 'bar'], 'whizz')
+            ->willReturn(['bang']);
 
-        $client = OpenSearch\ClientBuilder::create()->setHosts(
-            [
-            [
-                'host' => 'foo.com'
-            ]
-            ]
-        )->build();
-        $host = $client->transport->getConnection();
-        $this->assertSame("foo.com", $host->getHost());
-        $this->assertSame(9200, $host->getPort());
-        $this->assertSame("http", $host->getTransportSchema());
-
-
-        $client = OpenSearch\ClientBuilder::create()->setHosts(
-            [
-            [
-                'host' => 'foo.com',
-                'port' => 9500,
-                'scheme' => 'https'
-            ]
-            ]
-        )->build();
-        $host = $client->transport->getConnection();
-        $this->assertSame("foo.com", $host->getHost());
-        $this->assertSame(9500, $host->getPort());
-        $this->assertSame("https", $host->getTransportSchema());
-
-
-        try {
-            $client = OpenSearch\ClientBuilder::create()->setHosts(
-                [
-                [
-                    'port' => 9200,
-                    'scheme' => 'http'
-                ]
-                ]
-            )->build();
-            $this->fail("Expected RuntimeException from missing host, none thrown");
-        } catch (OpenSearch\Common\Exceptions\RuntimeException $e) {
-            // good
-        }
-
-        // Underscore host, questionably legal
-        $client = OpenSearch\ClientBuilder::create()->setHosts(
-            [
-            [
-                'host' => 'the_foo.com'
-            ]
-            ]
-        )->build();
-        $host = $client->transport->getConnection();
-        $this->assertSame("the_foo.com", $host->getHost());
-        $this->assertSame(9200, $host->getPort());
-        $this->assertSame("http", $host->getTransportSchema());
-
-
-        // Special characters in user/pass, would break inline
-        $client = OpenSearch\ClientBuilder::create()->setHosts(
-            [
-            [
-                'host' => 'foo.com',
-                'user' => 'user',
-                'pass' => 'abc#$@?%!abc'
-            ]
-            ]
-        )->build();
-        $host = $client->transport->getConnection();
-        $this->assertSame("foo.com", $host->getHost());
-        $this->assertSame(9200, $host->getPort());
-        $this->assertSame("http", $host->getTransportSchema());
-        $this->assertSame("user:abc#$@?%!abc", $host->getUserPass());
-    }
-
-    public function testClientLazy()
-    {
-        $handler = new MockHandler([
-          'status' => 200,
-          'transfer_stats' => [
-             'total_time' => 100
-          ],
-          'body' => '{test}',
-          'effective_url' => 'localhost'
+        $response = $this->client->request('GET', '/', [
+            'params' => ['foo' => 'bar'],
+            'body' => 'whizz',
         ]);
-        $builder = ClientBuilder::create();
-        $builder->setHosts(['somehost']);
-        $builder->setHandler($handler);
-        $client = $builder->build();
-
-        $params = [
-            'client' => [
-                'future' => 'lazy',
-            ]
-        ];
-        $result = $client->info($params);
-        $this->assertInstanceOf(FutureArray::class, $result);
-    }
-
-    public function testExtractArgumentIterable()
-    {
-        $client = OpenSearch\ClientBuilder::create()->build();
-        // array iterator can be casted to array back, so make more real with IteratorIterator
-        $body = new \IteratorIterator(new \ArrayIterator([1, 2, 3]));
-        $params = ['body' => $body];
-        $argument = $client->extractArgument($params, 'body');
-        $this->assertEquals($body, $argument);
-        $this->assertCount(0, $params);
-        $this->assertInstanceOf(\IteratorIterator::class, $argument);
-    }
-
-    /** @test */
-    public function sendRawRequest(): void
-    {
-        $transport = $this->createMock(OpenSearch\Transport::class);
-        $endpointFactory = $this->createMock(OpenSearch\EndpointFactoryInterface::class);
-        $client = new OpenSearch\Client($transport, $endpointFactory, []);
-
-        $transport->expects($this->once())->method('performRequest')->with('GET', '/', [], null, []);
 
-        $client->request('GET', '/');
+        $this->assertEquals(['bang'], $response);
     }
 
-    /** @test */
-    public function sendRawRequestWithBody(): void
-    {
-        $transport = $this->createMock(OpenSearch\Transport::class);
-        $endpointFactory = $this->createMock(OpenSearch\EndpointFactoryInterface::class);
-        $client = new OpenSearch\Client($transport, $endpointFactory, []);
-        $body = ['query' => ['match' => ['text_entry' => 'long live king']]];
-
-        $transport->expects($this->once())->method('performRequest')->with('GET', '/shakespeare/_search', [], $body, []);
-
-        $client->request('GET', '/shakespeare/_search', compact('body'));
-    }
-
-    /** @test */
-    public function sendRawRequestWithParams(): void
-    {
-        $transport = $this->createMock(OpenSearch\Transport::class);
-        $endpointFactory = $this->createMock(OpenSearch\EndpointFactoryInterface::class);
-        $client = new OpenSearch\Client($transport, $endpointFactory, []);
-        $params = ['foo' => 'bar'];
-
-        $transport->expects($this->once())->method('performRequest')->with('GET', '/_search', $params, null, []);
-
-        $client->request('GET', '/_search', compact('params'));
-    }
-
-    /** @test */
-    public function sendRawRequestWithOptions(): void
-    {
-        $transport = $this->createMock(OpenSearch\Transport::class);
-        $endpointFactory = $this->createMock(OpenSearch\EndpointFactoryInterface::class);
-        $client = new OpenSearch\Client($transport, $endpointFactory, []);
-        $options = ['client' => ['future' => 'lazy']];
-
-        $transport->expects($this->once())->method('performRequest')->with('GET', '/', [], null, $options);
-
-        $client->request('GET', '/', compact('options'));
-    }
 }
diff --git a/tests/Endpoints/AbstractEndpointTest.php b/tests/Endpoints/AbstractEndpointTest.php
index 7a3e7b87..5c28ca69 100644
--- a/tests/Endpoints/AbstractEndpointTest.php
+++ b/tests/Endpoints/AbstractEndpointTest.php
@@ -21,18 +21,17 @@
 
 namespace OpenSearch\Tests\Endpoints;
 
+use OpenSearch\EndpointInterface;
 use OpenSearch\Endpoints\AbstractEndpoint;
 use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
 
 /**
  * @covers \OpenSearch\Endpoints\AbstractEndpoint
  */
-class AbstractEndpointTest extends \PHPUnit\Framework\TestCase
+class AbstractEndpointTest extends TestCase
 {
-    /**
-     * @var AbstractEndpoint&MockObject
-     */
-    private $endpoint;
+    private EndpointInterface&MockObject $endpoint;
 
     protected function setUp(): void
     {
diff --git a/tests/HttpTransportTest.php b/tests/HttpTransportTest.php
new file mode 100644
index 00000000..6c566bb1
--- /dev/null
+++ b/tests/HttpTransportTest.php
@@ -0,0 +1,57 @@
+<?php
+
+namespace OpenSearch\Tests;
+
+use OpenSearch\HttpTransport;
+use OpenSearch\RequestFactoryInterface;
+use OpenSearch\Serializers\SmartSerializer;
+use PHPUnit\Framework\TestCase;
+use Psr\Http\Client\ClientInterface;
+use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\StreamInterface;
+
+/**
+ * Tests the HTTP transport.
+ *
+ * @coversDefaultClass \OpenSearch\HttpTransport
+ */
+class HttpTransportTest extends TestCase
+{
+    /**
+     * @covers ::sendRequest
+     */
+    public function testHttpTransport(): void
+    {
+        $request = $this->createMock(RequestInterface::class);
+
+        $requestFactory = $this->createMock(RequestFactoryInterface::class);
+        $requestFactory->expects($this->once())
+            ->method('createRequest')
+            ->with($this->anything())
+            ->willReturn($request);
+
+        $bodyStream = $this->createMock(StreamInterface::class);
+        $bodyStream->expects($this->once())
+            ->method('getContents')
+            ->willReturn('{"foo":"bar"}');
+
+        $response = $this->createMock(ResponseInterface::class);
+        $response->expects($this->once())
+            ->method('getBody')
+            ->willReturn($bodyStream);
+
+        $client = $this->createMock(ClientInterface::class);
+        $client->expects($this->once())
+            ->method('sendRequest')
+            ->with($request)
+            ->willReturn($response);
+
+        $serializer = new SmartSerializer();
+
+        $transport = new HttpTransport($client, $requestFactory, $serializer);
+        $response = $transport->sendRequest('GET', '/');
+
+        $this->assertEquals(['foo' => 'bar'], $response);
+    }
+}
diff --git a/tests/TransportTest.php b/tests/LegacyTransportTest.php
similarity index 97%
rename from tests/TransportTest.php
rename to tests/LegacyTransportTest.php
index 96469261..582f87ca 100644
--- a/tests/TransportTest.php
+++ b/tests/LegacyTransportTest.php
@@ -21,19 +21,23 @@
 
 namespace OpenSearch\Tests;
 
+use GuzzleHttp\Ring\Future\FutureArray;
+use GuzzleHttp\Ring\Future\FutureArrayInterface;
 use OpenSearch\Common\Exceptions\ServerErrorResponseException;
 use OpenSearch\ConnectionPool\AbstractConnectionPool;
 use OpenSearch\Connections\Connection;
-use OpenSearch\Serializers\SerializerInterface;
 use OpenSearch\Transport;
-use GuzzleHttp\Ring\Future\FutureArray;
-use GuzzleHttp\Ring\Future\FutureArrayInterface;
 use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
 use Psr\Log\LoggerInterface;
 use React\Promise\Deferred;
 
-class TransportTest extends TestCase
+/**
+ * Legacy transport test.
+ *
+ * @group legacy
+ */
+class LegacyTransportTest extends TestCase
 {
     /**
      * @var Connection|MockObject
diff --git a/util/Endpoint.php b/util/Endpoint.php
index c91ab10f..4b7fc189 100644
--- a/util/Endpoint.php
+++ b/util/Endpoint.php
@@ -544,15 +544,18 @@ private function extractParamsDescription(int $space): string
             if (in_array($param, $this->addedPartInDoc)) {
                 continue;
             }
+            $type = $values['type'] ?? 'any';
+            //            var_dump($type);
+            //            var_dump($values);
             $result .= sprintf(
                 "     * \$params['%s']%s = (%s) %s%s%s%s\n",
                 $param,
                 str_repeat(' ', $space - strlen($param)),
-                $values['type'] ?? 'any',
+                $type,
                 $values['description'] ?? '',
                 isset($values['required']) && $values['required'] ? ' (Required)' : '',
                 isset($values['options']) ? sprintf(" (Options = %s)", implode(',', $values['options'])) : '',
-                isset($values['default']) ? sprintf(" (Default = %s)", $values['type'] === 'boolean' ? ($values['default'] ? 'true' : 'false') : (is_array($values['default']) ? implode(',', $values['default']) : $values['default'])) : ''
+                isset($values['default']) ? sprintf(" (Default = %s)", ($type === 'boolean') ? ($values['default'] ? 'true' : 'false') : (is_array($values['default']) ? implode(',', $values['default']) : $values['default'])) : ''
             );
         }
         return $result;
diff --git a/util/template/client-class b/util/template/client-class
index 99971086..53782840 100644
--- a/util/template/client-class
+++ b/util/template/client-class
@@ -21,13 +21,10 @@ declare(strict_types=1);
 
 namespace OpenSearch;
 
-use OpenSearch\Common\Exceptions\BadMethodCallException;
-use OpenSearch\Common\Exceptions\NoNodesAvailableException;
 use OpenSearch\Endpoints\AbstractEndpoint;
-use OpenSearch\Namespaces\NamespaceBuilderInterface;
 use OpenSearch\Namespaces\BooleanRequestWrapper;
+use OpenSearch\Namespaces\NamespaceBuilderInterface;
 :use-namespaces
-use OpenSearch\Traits\DeprecatedPropertyTrait;
 
 /**
  * Class Client
@@ -41,9 +38,13 @@ class Client
 
     /**
      * @var Transport
+     *
+     * @deprecated in 2.3.2 and will be removed in 3.0.0.
      */
     public $transport;
 
+    private TransportInterface $httpTransport;
+
     /**
      * @var array
      */
@@ -67,13 +68,19 @@ class Client
     /**
      * Client constructor
      *
-     * @param Transport $transport
+     * @param TransportInterface|Transport $transport
      * @param callable|EndpointFactoryInterface $endpointFactory
      * @param NamespaceBuilderInterface[] $registeredNamespaces
      */
-    public function __construct(Transport $transport, callable|EndpointFactoryInterface $endpointFactory, array $registeredNamespaces)
+    public function __construct(TransportInterface|Transport $transport, callable|EndpointFactoryInterface $endpointFactory, array $registeredNamespaces)
     {
-        $this->transport = $transport;
+        if (!$transport instanceof TransportInterface) {
+            @trigger_error('Passing an instance of \OpenSearch\Transport to ' . __METHOD__ . '() is deprecated in 2.3.2 and will be removed in 3.0.0. Pass an instance of \OpenSearch\TransportInterface instead.', E_USER_DEPRECATED);
+            $this->transport = $transport;
+            $this->httpTransport = new LegacyTransportWrapper($transport);
+        } else {
+            $this->httpTransport = $transport;
+        }
         if (is_callable($endpointFactory)) {
             @trigger_error('Passing a callable as the $endpointFactory param in ' . __METHOD__ . ' is deprecated in 2.3.2 and will be removed in 3.0.0. Pass an instance of \OpenSearch\EndpointFactoryInterface instead.', E_USER_DEPRECATED);
             $endpoints = $endpointFactory;
@@ -103,14 +110,14 @@ class Client
      * Catchall for registered namespaces
      *
      * @return object
-     * @throws BadMethodCallException if the namespace cannot be found
+     * @throws \BadMethodCallException if the namespace cannot be found
      */
     public function __call(string $name, array $arguments)
     {
         if (isset($this->registeredNamespaces[$name])) {
             return $this->registeredNamespaces[$name];
         }
-        throw new BadMethodCallException("Namespace [$name] not found");
+        throw new \BadMethodCallException("Namespace [$name] not found");
     }
 
     /**
@@ -133,34 +140,33 @@ class Client
     }
 
     /**
-     * Sends a raw request to the cluster
-     * @return callable|array
-     * @throws NoNodesAvailableException
+     * Send a raw request to the cluster.
+     *
+     * @throws \Psr\Http\Client\ClientExceptionInterface
      */
-    public function request(string $method, string $uri, array $attributes = [])
+    public function request(string $method, string $uri, array $attributes = []): array|string|null
     {
         $params = $attributes['params'] ?? [];
         $body = $attributes['body'] ?? null;
         $options = $attributes['options'] ?? [];
 
-        $promise = $this->transport->performRequest($method, $uri, $params, $body, $options);
-
-        return $this->transport->resultOrFuture($promise, $options);
+        return $this->httpTransport->sendRequest($method, $uri, $params, $body, $options['headers'] ?? []);
     }
 
     /**
-     * @return callable|array
+     * Send a request for an endpoint.
+     *
+     * @throws \Psr\Http\Client\ClientExceptionInterface
      */
-    private function performRequest(AbstractEndpoint $endpoint)
+    private function performRequest(AbstractEndpoint $endpoint): array|string|null
     {
-        $promise =  $this->transport->performRequest(
+        return $this->httpTransport->sendRequest(
             $endpoint->getMethod(),
             $endpoint->getURI(),
             $endpoint->getParams(),
             $endpoint->getBody(),
             $endpoint->getOptions()
         );
-
-        return $this->transport->resultOrFuture($promise, $endpoint->getOptions());
     }
+
 }
diff --git a/util/template/endpoint-function-bool b/util/template/endpoint-function-bool
index d4c90d6d..f38a848a 100644
--- a/util/template/endpoint-function-bool
+++ b/util/template/endpoint-function-bool
@@ -8,5 +8,5 @@
         $endpoint = $this->endpointFactory->getEndpoint(:EndpointClass::class);
         $endpoint->setParams($params);
 :setparam
-        return BooleanRequestWrapper::performRequest($endpoint, $this->transport);
+        return BooleanRequestWrapper::sendRequest($endpoint, $this->httpTransport);
     }
diff --git a/util/template/namespace-class b/util/template/namespace-class
index 7ea1ddd8..6a1c0d23 100644
--- a/util/template/namespace-class
+++ b/util/template/namespace-class
@@ -4,8 +4,6 @@ declare(strict_types=1);
 
 namespace OpenSearch\Namespaces;
 
-use OpenSearch\Namespaces\AbstractNamespace;
-
 /**
  * Class :namespace
  *
diff --git a/util/template/namespace-property b/util/template/namespace-property
index 7b88dd7f..c7ae3a27 100644
--- a/util/template/namespace-property
+++ b/util/template/namespace-property
@@ -2,4 +2,3 @@
      * @var :namespaceNamespace
      */
     protected $:var_namespace;
-    
\ No newline at end of file
diff --git a/util/template/set-bulk-body b/util/template/set-bulk-body
index ece8963f..4ec05057 100644
--- a/util/template/set-bulk-body
+++ b/util/template/set-bulk-body
@@ -1,20 +1,22 @@
 
-    public function setBody($body): static
+    public function setBody(string|iterable|null $body): static
     {
-        if (isset($body) !== true) {
+        if (is_null($body)) {
             return $this;
         }
-        if (is_array($body) === true || $body instanceof Traversable) {
-            foreach ($body as $item) {
-                $this->body .= $this->serializer->serialize($item) . "\n";
+
+        if (is_string($body)) {
+            if (!str_ends_with($body, "\n")) {
+                $body .= "\n";
             }
-        } elseif (is_string($body)) {
             $this->body = $body;
-            if (substr($body, -1) != "\n") {
-                $this->body .= "\n";
-            }
-        } else {
-            throw new InvalidArgumentException("Body must be an array, traversable object or string");
+            return $this;
         }
+
+        // Must be an iterable.
+        foreach ($body as $item) {
+            $this->body .= $this->serializer->serialize($item) . "\n";
+        }
+
         return $this;
     }
diff --git a/util/template/set-part b/util/template/set-part
index e84cc82e..47e7d422 100644
--- a/util/template/set-part
+++ b/util/template/set-part
@@ -1,7 +1,7 @@
 
     public function set:Part($:part): static
     {
-        if (isset($:part) !== true) {
+        if (is_null($:part)) {
             return $this;
         }
         $this->:part = $:part;