diff --git a/legend-engine-xts-hostedService/legend-engine-xt-hostedService-pure/src/main/resources/core_hostedservice.definition.json b/legend-engine-xts-hostedService/legend-engine-xt-hostedService-pure/src/main/resources/core_hostedservice.definition.json
index 6043e6c58dc..4b56cd2529d 100644
--- a/legend-engine-xts-hostedService/legend-engine-xt-hostedService-pure/src/main/resources/core_hostedservice.definition.json
+++ b/legend-engine-xts-hostedService/legend-engine-xt-hostedService-pure/src/main/resources/core_hostedservice.definition.json
@@ -2,7 +2,6 @@
   "name": "core_hostedservice",
   "pattern": "(meta::external::function::activator::hostedService|meta::protocols)(::.*)?",
   "dependencies": [
-    "platform",
     "platform",
     "platform_dsl_graph",
     "platform_dsl_mapping",
diff --git a/legend-engine-xts-hostedService/legend-engine-xt-hostedService-pure/src/main/resources/core_hostedservice/generation/generation.pure b/legend-engine-xts-hostedService/legend-engine-xt-hostedService-pure/src/main/resources/core_hostedservice/generation/generation.pure
index c2b3322ce9f..370d4609638 100644
--- a/legend-engine-xts-hostedService/legend-engine-xt-hostedService-pure/src/main/resources/core_hostedservice/generation/generation.pure
+++ b/legend-engine-xts-hostedService/legend-engine-xt-hostedService-pure/src/main/resources/core_hostedservice/generation/generation.pure
@@ -23,6 +23,7 @@ function meta::external::function::activator::hostedService::generation::printPl
 
 function meta::external::function::activator::hostedService::validator::validateService(s:HostedService[1]):Boolean[1]
 {
+  $s->validateFunctionParamsInPattern();
   $s.function->validateFunction();
   $s->validateReturnType();
 }
@@ -35,6 +36,31 @@ function meta::external::function::activator::hostedService::validator::validate
   );
 }
 
+function meta::external::function::activator::hostedService::validator::validateFunctionParamsInPattern(h:HostedService[1]): Boolean[1]
+{
+  let pattern = $h.pattern;
+  assert($pattern->startsWith('/'),'Pattern must start with backslash');
+  let params  = $h.function->functionType().parameters->evaluateAndDeactivate();
+  let oneParams  = $params->filter(p|$p->deactivate().multiplicity == PureOne);
+  let nonOneParams  = $params->filter(p|!$p->deactivate().multiplicity == PureOne);
+  //all [1] params in pattern
+  $oneParams->map(p| assert($pattern->contains('{'+$p.name+'}'), 'Parameter '+$p.name+' with multiplicty [1] must be in service pattern.'));
+  //all non [1] params not in pattern
+  $nonOneParams->map(p| assert($pattern->contains('{'+$p.name+'}'), 'Parameter '+$p.name+' with multiplicty not [1] cannot be in service pattern.'));
+  //Service has a base pattern
+  let firstParamIndex = $pattern->indexOf('{');
+
+  assert(if($firstParamIndex != -1,| $firstParamIndex != 1,| true), 'Service must have a base pattern. Cannot start with a parameter');
+  //no param in pattern that doesnt exist in function
+  if($firstParamIndex!=-1,
+  |
+    let withoutBase = $pattern->substring($firstParamIndex, $pattern->length());
+    let leftOver = $oneParams.name->fold({b, a| $a->replace('{'+$b+'}','')}, $withoutBase->replace('/',''));
+    assert($leftOver->length()==0, 'Found unexpected params in pattern: '+$leftOver->replace('{','')->replace('}',' ')->trim()->replace(' ',','));,
+  | true);
+  true;
+}
+
 function meta::external::function::activator::hostedService::validator::validateFunction(func:Function<Any>[1]): Boolean[1]
 {
   $func->match([
@@ -70,7 +96,7 @@ function meta::external::function::activator::hostedService::generation::needsSe
 function meta::external::function::activator::hostedService::generation::recomposeServiceFunction(service:HostedService[1]):HostedService[1]
 {
   let result = if($service.function->functionReturnType()->needsSerialization(),
-                  |let tree = getTree($service.function); println($service.function->functionReturnType().rawType);
+                  |let tree = getTree($service.function); //println($service.function->functionReturnType().rawType);
                     assert($service.binding->isNotEmpty() || $service.contentType->isNotEmpty() , 'Service needs serialization but no binding/contentType provides');
                     let binding = if($service.binding->isNotEmpty(),
                                     |$service.binding,
diff --git a/legend-engine-xts-hostedService/legend-engine-xt-hostedService-pure/src/main/resources/core_hostedservice/showcase/showcaseServices.pure b/legend-engine-xts-hostedService/legend-engine-xt-hostedService-pure/src/main/resources/core_hostedservice/showcase/showcaseServices.pure
index fc0350c5161..fed10a366c6 100644
--- a/legend-engine-xts-hostedService/legend-engine-xt-hostedService-pure/src/main/resources/core_hostedservice/showcase/showcaseServices.pure
+++ b/legend-engine-xts-hostedService/legend-engine-xt-hostedService-pure/src/main/resources/core_hostedservice/showcase/showcaseServices.pure
@@ -25,7 +25,7 @@ function meta::external::function::activator::hostedService::tests::simpleServic
 {
   let service =  ^HostedService
    (
-      pattern = '/service/{var}',
+      pattern = '/service',
       ownership = ^UserList(users = ['debelp', 'harted']),
       documentation = 'bla bla',
       autoActivateUpdates = true,
@@ -54,7 +54,7 @@ function meta::external::function::activator::hostedService::tests::simpleServic
 {
   let service =  ^HostedService
    (
-      pattern = '/service/{var}',
+      pattern = '/service',
       ownership = ^UserList(users = ['debelp', 'harted']),
       documentation = 'bla bla',
       autoActivateUpdates = true,
@@ -84,7 +84,7 @@ function meta::external::function::activator::hostedService::tests::simpleServic
 {
   let service =  ^HostedService
    (
-      pattern = '/service/{var}',
+      pattern = '/service',
       ownership = ^UserList(users = ['debelp', 'harted']),
       documentation = 'bla bla',
       autoActivateUpdates = true,
@@ -109,7 +109,7 @@ function meta::external::function::activator::hostedService::tests::simpleServic
 {
   let service =  ^HostedService
    (
-      pattern = '/service/{var}',
+      pattern = '/service',
       ownership = ^UserList(users = ['debelp', 'harted']),
       documentation = 'bla bla',
       autoActivateUpdates = true,
@@ -136,7 +136,7 @@ function meta::external::function::activator::hostedService::tests::simpleServic
 {
   let service =  ^HostedService
    (
-      pattern = '/service/{var}',
+      pattern = '/service',
       ownership = ^UserList(users = ['debelp', 'harted']),
       documentation = 'bla bla',
       autoActivateUpdates = true,
@@ -163,7 +163,7 @@ function meta::external::function::activator::hostedService::tests::simpleServic
 {
   let service =  ^HostedService
    (
-      pattern = '/service/{var}',
+      pattern = '/service',
       ownership = ^UserList(users = ['debelp', 'harted']),
       binding = ^Binding(name='serviceBinding', contentType = 'application/json',modelUnit = meta::pure::model::unit::newModelUnit()->include(PersonX)),
       documentation = 'bla bla',
@@ -182,7 +182,7 @@ function meta::external::function::activator::hostedService::tests::simpleServic
 {
   let service =  ^HostedService
    (
-      pattern = '/service/{var}',
+      pattern = '/service',
       ownership = ^UserList(users = ['debelp', 'harted']),
       contentType =  'application/json',
       documentation = 'bla bla',
@@ -230,7 +230,7 @@ function meta::external::function::activator::hostedService::tests::simpleServic
 {
   let service =  ^HostedService
    (
-      pattern = '/service/{var}',
+      pattern = '/service',
       ownership = ^UserList(users = ['debelp', 'harted']),
       contentType =  'application/json',
       documentation = 'bla bla',
@@ -291,7 +291,7 @@ function meta::external::function::activator::hostedService::tests::simpleServic
 {
   let service =  ^HostedService
    (
-      pattern = '/service/{var}',
+      pattern = '/service',
       ownership = ^UserList(users = ['debelp', 'harted']),
       documentation = 'bla bla',
       binding = ^Binding(name='serviceBinding', contentType = 'application/json',modelUnit = meta::pure::model::unit::newModelUnit()->include(PersonX)),
@@ -322,11 +322,11 @@ function meta::external::function::activator::hostedService::tests::simpleServic
 {
   let service =  ^HostedService
    (
-      pattern = '/service/{var}',
+      pattern = '/service/{name}/{length}',
       ownership = ^UserList(users = ['debelp', 'harted']),
       documentation = 'bla bla',
       autoActivateUpdates = true,
-      function= meta::external::function::activator::hostedService::tests::simpleRelationalfunction_String_1__TabularDataSet_1_
+      function= meta::external::function::activator::hostedService::tests::simpleRelationalfunction_String_1__Integer_1__TabularDataSet_1_
    );
   //validate
   $service->meta::external::function::activator::hostedService::validator::validateService();
@@ -334,9 +334,9 @@ function meta::external::function::activator::hostedService::tests::simpleServic
    $service->meta::external::function::activator::hostedService::generation::printPlan();
 }
 
-function meta::external::function::activator::hostedService::tests::simpleRelationalfunction(name:String[1]):TabularDataSet[1]
+function meta::external::function::activator::hostedService::tests::simpleRelationalfunction(name:String[1], length:Integer[1]):TabularDataSet[1]
 {
-    PersonX.all()->filter(p|$p.firstName == $name)->project([col(p|$p.firstName, 'firstName'), col(p|$p.lastName, 'lastName')])
+    PersonX.all()->filter(p|$p.firstName == $name || $p.lastName->length()==$length) ->project([col(p|$p.firstName, 'firstName'), col(p|$p.lastName, 'lastName')])
     ->from(simpleRelationalMapping, testRuntime(dbInc))
 }
 
@@ -346,7 +346,7 @@ function meta::external::function::activator::hostedService::tests::simpleServic
 {
   let service =  ^HostedService
    (
-      pattern = '/service/{var}',
+      pattern = '/service/{tree}',
       ownership = ^UserList(users = ['debelp', 'harted']),
       documentation = 'bla bla',
       binding = ^Binding(name='serviceBinding', contentType = 'application/json',modelUnit = meta::pure::model::unit::newModelUnit()->include(PersonX)),