HTTP Endpoint

The HTTP endpoint allows you to define REST endpoints using URI templates similar to the REST API. The URI templates allow a RESTful URI to contain variables that can be populated during mediation runtime using property values whose names have the "uri.var." prefix. An HTTP endpoint can also define the particular HTTP method to use in the RESTful invocation.

XML Configuration

The syntax is as follows.

<http uri-template="URI Template" method="GET|POST|PATCH|PUT|DELETE|OPTIONS|HEAD" />

HTTP Endpoint Attributes

<http uri-template="http://{uri.var.host}:{uri.var.port}/{uri.var.context1}/services/{uri.var.context2}{uri.var.postfix}" method="get">

UI Configuration

The following page is opened by clicking HTTP Endpoint in the Add Endpoint tab of the Manage Endpoints page.

The parameters to configure an HTTP endpoint are as follows.

You can create HTTP endpoints by specifying values for the parameters given above.

Alternatively, you can specify one parameter as the HTTP endpoint by using multiple other parameters, and then pass that to define the HTTP endpoint as follows:

<property name="uri.var.httpendpointurl" expression="fn:concat($ctx:prefixuri, $ctx:host, $ctx:port, $ctx:urlparam1, $ctx:urlparam2)" />
<send>
<endpoint>
<http uri-template="
{uri.var.httpendpointurl}
"/>
</endpoint>
</send>

Examples

Example 1 - populating an HTTP endpoint during mediation

<endpoint xmlns="http://ws.apache.org/ns/synapse" name="HTTPEndpoint">
    <http uri-template="http://localhost:8080/{uri.var.servicepath}/restapi/{uri.var.servicename}/menu?category={uri.var.category}&amp;type={uri.var.pizzaType}" method="GET">
</http>
</endpoint>

The URI template variables in this example HTTP endpoint can be populated during mediation as follows:

<inSequence>           
            <property name="uri.var.servicepath" value="PizzaShopServlet"/>
            <property name="uri.var.servicename" value="PizzaWS"/>
            <property name="uri.var.category" value="pizza"/>
            <property name="uri.var.pizzaType" value="pan"/>
            <send>
                <endpoint key="HTTPEndpoint"/>
            </send>
</inSequence>

This configuration will cause the RESTful URL to evaluate to:

http://localhost:8080/PizzaShopServlet/restapi/PizzaWS/menu?category=pizza&type=pan

Example 2 - Sending a Message from a WebSocket Client to an HTTP Endpoint

The following sections walk you through a sample scenario that demonstrates how to send a message from a WebSocket client to an HTTP endpoint via the ESB Profile of WSO2 Enterprise Integrator (WSO2 EI):

Introduction

If you need to send a message from a WebSocket client to an HTTP endpoint via the ESB Profile of WSO2 EI, you need to establish a persistent WebSocket connection from the WebSocket client to the ESB Profile of WSO2 EI.
To demonstrate this scenario, you need to create two dispatching sequences. One for the client to back-end mediation, and another for the back-end to client mediation. Finally you need to configure the WebSocket inbound endpoint of the ESB Profile of WSO2 EI to use the created sequences and listen on port 9091.

Prerequisites

• Start the ESB Profile of WSO2 EI. For information on how to start the ESB Profile, see Running the Product.
• Download the sample netty artifacts.

Configuring the sample scenario

• Create the sequence for client to back-end mediation as follows:

  <sequence name="dispatchSeq">
    <switch source="get-property('websocket.source.handshake.present')">
      <case regex="true">
        <drop/>
      </case>
      <default>
        <call>
          <endpoint>
           <address uri="http://www.mocky.io/v2/56f84ee5240000d1127866c8"/>
          </endpoint>
        </call>
       <respond/>
       </default>
     </switch>
  </sequence>

  This sequence calls an HTTP endpoint.

• Create the sequence for back-end to client mediation as follows:

  <sequence name="outDispatchSeq" xmlns="http://ws.apache.org/ns/synapse">
    <log/>
    <respond/>
  </sequence>

• Configure the WebSocket inbound endpoint in the ESB Profile of WSO2 EI as follows to use the created sequences and listen on port 9091:

  <inboundEndpoint name="test" onError="falut" protocol="ws"
     	sequence="dispatchSeq" suspend="false">
     	<parameters>
         	<parameter name="inbound.ws.port">9091</parameter>
         	<parameter name="ws.outflow.dispatch.sequence">outDispatchSeq</parameter>
         	<parameter name="ws.client.side.broadcast.level">0</parameter>
         	<parameter name="ws.outflow.dispatch.fault.sequence">fault</parameter>
     	</parameters>
  </inboundEndpoint>

Executing the sample scenario

• Execute the following command to start the WebSocket client:

  java -DclientPort=9091 -cp netty-example-4.0.30.Final.jar:lib/*:. io.netty.example.http.websocketx.client.WebSocketClient

Analyzing the output

If you analyze the log, you will see that a connection from the WebSocket client to the ESB Profile of WSO2 EI is established. You will also see that the sequences are executed by the WebSocket inbound endpoint.