docs: new concept doc application (#992)

Co-authored-by: Lukasz Gornicki <[email protected]>
Co-authored-by: akshatnema <[email protected]>

pages/docs/concepts/application.md

@@ -0,0 +1,42 @@
+---
+title: Application
+weight: 23
+---
+
+
+## What is an application?
+An application is any computer program or a group of them. 
+
+An application could also be a micro-service, IoT device (sensor), mainframe process, etc. Users may even write applications in different programming languages if they support one of the selected protocols. 
+
+## Why do we need applications?
+In Event-Driven Architecture (EDA), an application must be a `producer`, a `consumer`, or both. Applications must also use the protocols the server supports if they wish to connect and exchange messages.
+
+### Applications: producers and consumers
+```mermaid
+flowchart TD
+        A[PRODUCER application] --> B[message] 
+        B --> C[channel] 
+        C --> D[message] 
+        D --> F[CONSUMER application]
+```
+The above diagram describes a message communication traveling through a channel between a **PRODUCER application** and a **CONSUMER application**. 
+
+<Remember>
+When writing your AsyncAPI document, make sure to describe what a user can do with your application; not what the application does. In other words, if your <em>application</em> is a <b>producer</b>, your AsyncAPI document should describe where users can subscribe to, to receive messages produced by your <b>producer</b> application. 
+</Remember>
+
+<DocsButton
+  suggestions={[
+    {
+      href: '/docs/concepts/channel',
+      title: 'Channel',
+      type:'back',
+    },
+    {
+      href: '/docs/concepts/protocol',
+      title: 'Protocol',
+      type:'next',
+    }
+  ]}
+/>

pages/docs/concepts/channel.md

@@ -30,9 +30,9 @@ The diagram above shows the communication between a `producer` and `consumer`, w
       title: 'Consumer',
    },
    {
-      href:'/docs/concepts/message',
+      href:'/docs/concepts/application',
       type: 'next',  
-      title: 'Message',
+      title: 'Application',
    }
  ]}
 />

pages/docs/concepts/message.md

@@ -38,9 +38,9 @@ Overall, `events` are `messages` but not all `messages` are `events`.
 <DocsButton
  suggestions={[
     {
-      href:'/docs/concepts/channel',
+      href:'/docs/concepts/protocol',
       type: 'back',  
-      title: 'Channel',
+      title: 'Protocol',
    },
    {
       href:'/docs/tutorials',

pages/docs/concepts/protocol.md

@@ -37,9 +37,9 @@ In AsyncAPI documents, all protocol-specific details that the application follow
       title: 'Application',
    },
    {
-      href:'/docs/tutorials',
+      href:'/docs/concepts/message',
       type: 'next',  
-      title: 'Tutorials - Overview',
+      title: 'Message',
    }
  ]}
 />