How to send a HTTP POST or PUT request with empty content message body into a backend server using WSO2 ESB

How to send a HTTP POST or PUT request with empty content message body into a backend server using WSO2 ESB

By the design, ESB expects a message body to send the request to backend server when the http method is POST or PUT. But you can overwrite this behavior by using the property FORCE_POST_PUT_NOBODY. Then you can post or put the request without message body or with the message body if exist to the backend server.

Bellow is the sample proxy service which capable for sending empty messages

<proxy xmlns="http://ws.apache.org/ns/synapse" name="httpendpoint" transports="https,http" statistics="disable" trace="disable" startOnLoad="true">  
   <target>  
    <inSequence>  
      <log level="full" />  
      <property name="FORCE_POST_PUT_NOBODY" value="true" scope="axis2" type="BOOLEAN" />  
    </inSequence>  
    <outSequence>  
      <send />  
    </outSequence>  
    <endpoint>  
      <http uri-template="http://localhost:8080/echoempty/echoemptyrequest" />  
    </endpoint>  
   </target>  
   <description />  
 </proxy>  

         
Then you can send the http messages as bellow to the proxy service.

POST /services/httpendpoint HTTP/1.1
Connection: keep-alive
Content-Type: application/x-www-form-urlencoded
Content-Length: 0
Host: 127.0.0.1:8282
User-Agent: Apache-HttpClient/4.2.3 (java 1.5) 

                     

How to Send a String Parameter to an Axis2 Web Service

If you have written a web service operation which accept a String parameter, You will not be able to pass a string value directly. The below operation is required a string parameter. Then you need to wrap the text inside the CDATA tag. Other wise it will not read the parameter value.

     public void echo(String request)  {
        System.out.println(request);
    }

If you want to send a simple string , You need to wrap it with CDATA. The the output will be >> "Text Content"

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:wso2="http://wso2.org">
   <soapenv:Header />
   <soapenv:Body>
      <wso2:echo>
         <!--Optional:-->
         <wso2:request><![CDATA[Text Content]]></wso2:request>
      </wso2:echo>
   </soapenv:Body>
</soapenv:Envelope>

If you want to pass a xml content as a string then you have to use CDATA tag as bellow.
Then the output will be >> "<foo>Test</foo>"

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:wso2="http://wso2.org">
   <soapenv:Header />
   <soapenv:Body>
      <wso2:echo>
         <!--Optional:-->
         <wso2:request><![CDATA[<foo>Test</foo>]]></wso2:request>
      </wso2:echo>
   </soapenv:Body>
</soapenv:Envelope> 

You need CDATA tag always to send the String value to a web service operation if they have String type parameter

How to append a query parameter to an API published from WSO2 API Manager

How to append a query parameter to an API published from WSO2 API Manager

There are some situations where you need to send some url query parameters with the request when publishing an API through the API Manager. But You do not need client to send those parameters with the request URL. In that case how do you append those parameters to the endpoint url. In this blog post see how to append a query parametr to endpoint url.

First you need to create an API and published the API. Please refer how to create an API to create an API in WSO2 API Manager.

Then the requirement is once you invoke the API with some query parameter, It will call the actual service endpoint with some other query parameter.

You can append query parameters to the endpoint url from API Manager. synapse property 'REST_URL_POSTFIX' can be used to manage the query parameter. Once you create an api, what you have to do is that, you need to update the synapse configuration of the api created with the relevant property. the property REST_URL_POSTFIX will give you the query string coming into the api from the client. Then you can change the query string as you need.

<property name="REST_URL_POSTFIX" expression="fn:concat(get-property('axis2','REST_URL_POSTFIX'), '&amp;exchange=xyz')" scope="axis2" type="STRING"/>

Once You create an API, You can add parameter by following bellow steps.
1) Login to AM(https://ipaddress:port/carbon/) and Click on main > Source View
Then you can see the synapse configuration

2) Find the api configuration you have created by the api name.

3) Then update the insequence of the api with bellow property.
<property name="REST_URL_POSTFIX" expression="fn:concat(get-property('axis2','REST_URL_POSTFIX'), '&amp;exchange=xyz')" scope="axis2" type="STRING"/>

4) Click on update button.

Then your api looks as bellow. 

 <api xmlns="http://ws.apache.org/ns/synapse" name="admin--testapi" context="/testapi" version="1.0.0" version-type="url">  
   <resource methods="GET" url-mapping="/*">  
     <inSequence>  
       <property name="POST_TO_URI" value="true" scope="axis2"/>  
       <property name="REST_URL_POSTFIX" expression="fn:concat(get-property('axis2','REST_URL_POSTFIX'), '&amp;exchange=xyz')" scope="axis2" type="STRING"/>  
       <filter source="$ctx:AM_KEY_TYPE" regex="PRODUCTION">  
         <then>  
           <send>  
             <endpoint name="admin--testapi_APIEndpoint_0">  
               <address uri="http://localhost:8080/stockquote/getQuote">  
                 <timeout>  
                   <duration>30000</duration>  
                   <responseAction>fault</responseAction>  
                 </timeout>  
                 <suspendOnFailure>  
                   <errorCodes>-1</errorCodes>  
                   <initialDuration>0</initialDuration>  
                   <progressionFactor>1.0</progressionFactor>  
                   <maximumDuration>0</maximumDuration>  
                 </suspendOnFailure>  
                 <markForSuspension>  
                   <errorCodes>-1</errorCodes>  
                 </markForSuspension>  
               </address>  
             </endpoint>  
           </send>  
         </then>  
         <else>  
           <sequence key="_sandbox_key_error_"/>  
         </else>  
       </filter>  
     </inSequence>  
     <outSequence>  
       <send/>  
     </outSequence>  
   </resource>  
   <handlers>  
     <handler class="org.wso2.carbon.apimgt.gateway.handlers.security.APIAuthenticationHandler"/>  
     <handler class="org.wso2.carbon.apimgt.gateway.handlers.throttling.APIThrottleHandler">  
       <property name="id" value="A"/>  
       <property name="policyKey" value="gov:/apimgt/applicationdata/tiers.xml"/>  
     </handler>  
     <handler class="org.wso2.carbon.apimgt.usage.publisher.APIMgtUsageHandler"/>  
     <handler class="org.wso2.carbon.apimgt.usage.publisher.APIMgtGoogleAnalyticsTrackingHandler"/>  
     <handler class="org.wso2.carbon.apimgt.gateway.handlers.ext.APIManagerExtensionHandler"/>  
   </handlers>  
 </api>

Ex: Client request  http://localhost:8280/testapi/1.0.0?symbol=abc
Actual request required for back end
http://localhost:8080/stockquote/getQuote?symbol=abc&exchange=xyz

Here you have added exchange parameter to the service call. As above you can modify the query string as you required.

How to secure your services with OAuth2 using WSO2 API Manager

Securing Your Service with OAuth2 Using WSO2 API Manager

If you host a service, You may need some access control on that service. Otherwise any one can access that service. In such case you can use WSO2 API Manager to achieve this easily. API Manager can secure your service with OAuth2.

I have a backend service host on apache tomcat server. It can be invoked both http GET and POST method.

if I send a bellow request, It will receive a response
http://localhost:8080/stockquote/getQuote?symbol=wso2

Response:
<getQuoteResponse>
       <symbol>wso2</symbol>
       <lastPrice>67.73111720684315</lastPrice>
       <company>wso2 Company</company>
       <timeStamp>Wed Mar 26 17:49:25 IST 2014</timeStamp></getQuoteResponse>

Then I am going to create an api on WSO API Manager (wso2am-1.6.0) and keep my actual backend service behind the API Manager.

Steps to create an api
1) First I start a wso2am-1.6.0
2) Login to Publisher using user credential admin
       https://localhost:9443/publisher/ 
3) Add a api with below parameters.

       Name    : stockQuoteApi
       Context : stockquote
       Version : 1.0.0
       Tier Availability : Gold
       Production Endpoint : http://localhost:8080/stockquote/getQuote

With the above parameters, We can create an api successfully.

4) Publish the created api
      Select the created api and change LifeCycle  to Publish

Then We have to subscribe for the created api.

5) Login to Store using user credential admin then you can see the api cretaed
       https://10.100.1.107:9443/store/
6) Then select the api. You can see the access URL of the created api "http://10.100.1.107:8280/stockQuote/1.0.0"
Then choose DefaultApplication in Applications drop down box lay on right corner.

7) Then Click On Subscribe button.

8) Then click On Generate button in Keys - Production. Then you can see the Access Token.

Now API Creation is completed.

Then Try to access the api. You can use any http client to access the service. Inv this case I am going to use curl.

Now I am trying to invoke the api with below command.

curl  http://localhost:8280/stockQuote/1.0.0?symbol=wso2

Then I will receive a below response.

<ams:fault xmlns:ams="http://wso2.org/apimanager/security">
     <ams:code>900902</ams:code>
     <ams:message>Missing Credentials</ams:message>
     <ams:description>Required OAuth credentials not provided</ams:description>
</ams:fault>

That means Your api is secured. So you need to provide the access token to invoke the service. You can find the access token in subscription page.

Then invoke the service with below command.

curl  -H "Authorization :Bearer gQsoJqhYv15f_JiEVg46y44olcUa" http://localhost:8280/stockQuote/1.0.0?symbol=wso2

Now I get the correct response which is provided by my actual backend service running on tomcat server.

<getQuoteResponse>
      <symbol>wso2</symbol>
      <lastPrice>147.95183566530514</lastPrice>
      <company>wso2 Company</company>
      <timeStamp>Wed Mar 26 18:32:30 IST 2014</timeStamp></getQuoteResponse>

As the below api, You can create any number of api to secure your services. It is very easy and useful.

How to add HTTP Basic Authentication header to the outgoing message of WSO2 ESB Proxy service

Here I am going to discuss how to access the web service secured by HTTP Basic Authentication via a proxy service deployed on WSO2 ESB.

The scenario is client invoke the proxy service without the Authorization header and WSO2 ESB proxy service add  the Authorization to out going message and call the actual backend service.

Here You need to set authorization header to HTTP request sent bu the ESB. You can achieve this by using property mediator  with the propert name Authorization.

<property xmlns:ns="http://org.apache.synapse/xsd"  
           name="Authorization"  
           expression="fn:concat('Basic ', base64Encode('username:password'))"  
           scope="transport"/>

Below is the header you need to send with the request.

authorization:Basic dXNlcm5hbWU6cGFzc3dvcmQ=


You can set this header within the proxy service by configuring property mediator as below.

<proxy xmlns="http://ws.apache.org/ns/synapse"  
     name="stockQuote"  
     transports="https,http"  
     statistics="disable"  
     trace="disable"  
     startOnLoad="true">  
   <target>  
    <inSequence>  
      <property name="symbol1" value="2" scope="default" type="STRING"/>  
      <property xmlns:ns="http://org.apache.synapse/xsd"  
           name="Authorization"  
           expression="fn:concat('Basic ', base64Encode('username:password'))"  
           scope="transport"/>  
      <send>  
       <endpoint>  
         <address uri="http://localhost:8080/echo/echoheaders"/>  
       </endpoint>  
      </send>  
    </inSequence>  
   </target>  
   <description/>  
 </proxy>

Then the outgoing request from the ESB will contains the authorization header and backend service can be accessed.

How to conver http POST request to http GET request using WSO2 ESB proxy service

In this blog, I am going to discuss how to send a HTTP GET request using WSO2 ESB proxy service. Here is the sample scenario.

Client sends a post request with a SOAP message to the proxy service and proxy service retrieve a parameter form the payload and make a HTTP get request with a URI parameter to get the response form the actual backend. Back end service is a rest service. Then Proxy service get the rest response and convert it in to SOAP message and send back to the client.

Below proxy configuration make above scenario worked.

Prerequisite
WSO2 ESB 4.7.0

<proxy xmlns="http://ws.apache.org/ns/synapse"
       name="stockQuote"
       transports="https,http"
       statistics="disable"
       trace="disable"
       startOnLoad="true">
   <target>
      <inSequence>
         <property name="symbol1" value="2" scope="default" type="STRING"/>
         <property xmlns:m1="http://services.samples/xsd"
                   xmlns:m0="http://services.samples"
                   name="symbol"
                   expression="//m0:getQuote/m0:request/m1:symbol"
                   scope="default"
                   type="STRING"/>
         <property xmlns:ns="http://org.apache.synapse/xsd"
                   name="REST_URL_POSTFIX"
                   expression="fn:concat('?symbol=',get-property('symbol1'))"
                   scope="axis2"
                   type="STRING"/>
         <log level="custom">
            <property name="url" expression="get-property('axis2','REST_URL_POSTFIX')"/>
         </log>
         <property name="HTTP_METHOD" value="GET" scope="axis2" type="STRING"/>
         <send>
            <endpoint>
               <address uri="http://localhost:8080/stockquote/getQuote" format="rest"/>
            </endpoint>
         </send>
      </inSequence>
      <outSequence>
         <property name="messageType" value="text/xml" scope="axis2"/>
         <send/>
      </outSequence>
   </target>
   <description/>
</proxy>
                                

Once you send a request with below payload to the stockquote proxy

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:ser="http://services.samples" xmlns:xsd="http://services.samples/xsd">  
   <soapenv:Header/>  
   <soapenv:Body>  
    <ser:getQuote>  
      <!--Optional:-->  
      <ser:request>  
       <!--Optional:-->  
       <xsd:symbol>wso2</xsd:symbol>  
      </ser:request>  
    </ser:getQuote>  
   </soapenv:Body>  
 </soapenv:Envelope>  

It will make a HTTP GET call to the URL and get back the response

http://localhost:8080/stockquote/getQuote?symbol=wso2

Then proxy service send response back to the client

How to enable WSO2 Carbon Management Console via HTTP Transport

WSO2 carbon product management console is only exposed in HTTPS by default due to the security aspects. Anyway if someone want to access the management console via HTTP, It also possible. You can just configure it and access.

To enable admin console via HTTP,

1) Go to the $WSO2_HOME/repository/conf and open carbon.xml
2) Uncomment the EnableHTTPAdminConsole property. 

 <EnableHTTPAdminConsole>true</EnableHTTPAdminConsole>

Then start the server. You can access the management console from http://127.0.0.1:9763/carbon/

How to increase the WSO2 carbon management console session timeout

In WSO2 carbon products, The default value of the management console session timeout is 15 minutes. if user is idle for more than 15 min, It expire the user session, Then user need to provide the credential again to  access the management console. if you need to increase the session time out you can just change it through the configuration

1) Go to repository/conf/tomcat/carbon/WEB-INF
2) Change the session-timeout value in web.xml file

     <session-config>
        <session-timeout>15</session-timeout>
    </session-config>

Please note that timeout is defined in minutes.

3) Restart the server

Then, Once you log into the web console, It keeps the user session as you configured.