How to access API definitions from the WSO2 API Manager

WSO2 API Manager provides an intuitive UI that can be used to add and configure API's that are exposed via the API Manager. However not all the capabilities of an API can be manipulated from the API Publisher's UI. Certain tweaks require the access to the API definitions directly. There are two possible ways of doing this.

1. Via the Management console of the API Manager

Access the Management console of the API Manager from the following URL and log-in using the admin credentials.
https://{IP}:{Port}/carbon/admin/login.jsp

Once inside the management console, you can see the source view icon on the left hand side navigation bar as indicated below. Navigate to the source view page.

Here you would find all the API definitions, you can change the API definitions as required.

2. Directly accessing the API definition from the file system of the API Gateway.

API definition is stored in the file-system of the API Gateway, you can access this from the following folder path.

{API-Manager_Home}/repository/deployment/server/synapse-configs/default/api

Each API is represented by a xml file. You can change the definition by changing the contents of the file. The changes would be hot deployed to the API Gateway.


Please be mindful of the changes you make as it affect the exposed API's. API's are defined in Apache Synapse hence you would need some level of knowledge on Apache Synapse to manipulate these files.

Returning multiple values from an Axis2 Service

Most of you who wants to create a quick Axis2 Service to mock a web-service would encounter a situation where you want to return more than 1 value from a service. You can simply return more than 1 value by returning a Hashmap. But this would return the values in the following format.

  value1



  value2



  value3

This would be a nightmare for any developer who would want to use the response from this service to perform message mediator or orchestration as all the XML elements share the same name ‘return’ making it impossible to extract values through XPath.

Solution for this problem is to return an object type from the Axis2 service. Given below is a sample code snippet on how this can be done.

Axis 2 service

public workOrderResponse getWorkOrders(String version){
             System.out.println( "City Works Service,get workorders ");
             return new workOrderResponse();
           
       }

WorkOrderResponse class

public class workOrderResponse {

       String workOrderId;
       String name;
       String address;

       public workOrderResponse (){
             workOrderId= "A1234";
             name= "WSO2 Inc";
             address=  "787 Castro Street, Mountain View, CA 94041";
            
       }

       public String getWorkOrderId() {
             return workOrderId;
       }

       public void setWorkOrderId(String workOrderId) {
             this.workOrderId = workOrderId;
       }

       public String getName() {
             return name;
       }

       public void setName(String name) {
             this.name = name;
       }

       public String getAddress() {
             return address;
       }

       public void setAddress(String address) {
             this.address = address;
       }

}

By returning an object, the Axis2 service would return values with correct XML elements names. XML element names would correspond to the variable names in the object. Given below is a sample response from the above service.

      A1234
      WSO2 Inc
      787 Castro Street, Mountain View, CA 94041

ESB Guaranteed Delivery with client acknowledgement for synchronous clients

A typical guaranteed delivery scenario covered as an Enterprise Integration ensures the delivery of a message to a given backend endpoint. As per this pattern the ESB would attempt to delivers the message to the backend endpoint and if it fails, the message would be stored and delivered once the backend endpoint becomes available. If the above guaranteed delivery mechanism is implemented to a message flow that is synchronous the client would be waiting for a response from the ESB until the message times out. To accommodate synchronous clients in a guaranteed delivery scenario, it is possible for the ESB to respond to the client with a fault message in case the message is not delivered and stored for later delivery. The following diagram depicts the message flow of the guaranteed delivery scenario with client acknowledgement using the WSO2 ESB.

1.      Client sends the message to the ESB.

2.      ESB try to deliver the message to the backend system, and the message fails

3.      ESB stores the message in a message queue

4.      ESB sends a response back to the client (response can be customized as required)

5.      ESB picks the message from the queue and try to deliver the message to the backend system; ESB retry can be customized to retry a given number of attempts.

The following synapse configuration can be used to configure this scenario. The configuration includes a proxy service, message broker, message processor, sequences and endpoints required to create the required mediation flow. Please note that the configuration is based on storing messages in an ActiveMQ based message queue. Hence it is required to follow the steps mentioned in the following link [1] setting up ActiveMQ with WSO2 ESB.

<proxy name="StockQuoteProxy"

          transports="https http"

          startOnLoad="true"

          trace="disable">

      <description/>

      <target>

         <inSequence>

            <sequence key="delivery_seq"/>

         </inSequence>

         <outSequence>

            <send/>

         </outSequence>

      </target>

  <publishWSDL uri="file:repository/samples/resources/proxy/sample_proxy_1.wsdl"/>

   </proxy>

   <endpoint name="queueEP">

      <address uri="http://localhost:9000/services/SimpleStockQuoteService"/>

   </endpoint>

   <endpoint name="StockQuoteFO">

   <address uri="http://localhost:9000/services/SimpleStockQuoteService"</endpoint>

   <sequence name="delivery_seq" onError="errorHandler">

      <enrich>

         <source type="envelope" clone="true"/>

         <target type="property" property="mssg"/>

      </enrich>

      <send>

         <endpoint key="StockQuoteFO"/>

      </send>

   </sequence>

   <sequence name="SendResponse">

      <header name="To" action="remove"/>

      <property name="RESPONSE" value="true"/>

      <send/>

   </sequence>

   <sequence name="errorHandler">

      <makefault version="soap11">

         <code xmlns:tns="http://www.w3.org/2003/05/soap-envelope" value="tns:Receiver"/>

         <reason value="Message has been stored."/>

      </makefault>

      <clone>

         <target sequence="SendResponse"/>

         <target sequence="queueMessage"/>

      </clone>

   </sequence>

  

   <sequence name="queueMessage">

      <enrich>

         <source type="property" clone="true" property="mssg"/>

         <target type="envelope"/>

      </enrich>

      <property name="target.endpoint" value="queueEP"/>

      <property name="FORCE_SC_ACCEPTED" value="true" scope="axis2"/>

      <property name="OUT_ONLY" value="true"/>

      <store messageStore="JMStore"/>

   </sequence>

  

   <messageStore class="org.apache.synapse.message.store.impl.jms.JmsStore"

                 name="JMStore">

      <parameter name="java.naming.factory.initial">org.apache.activemq.jndi.ActiveMQInitialContextFactory</parameter>

      <parameter name="store.jms.cache.connection">false</parameter>

      <parameter name="java.naming.provider.url">tcp://localhost:61616</parameter>

      <parameter name="store.jms.JMSSpecVersion">1.1</parameter>

   </messageStore>

   <messageProcessor class="org.apache.synapse.message.processor.impl.forwarder.ScheduledMessageForwardingProcessor"

                     name="ScheduledProcessor"

                     messageStore="JMStore">

      <parameter name="interval">20000</parameter>

      <parameter name="is.active">true</parameter>

   </messageProcessor>

[1] https://docs.wso2.com/display/ESB481/Configure+with+ActiveMQ

Restricting grant types for an application in WSO2 API Manager

WSO2 API Manager has the capability of restricting which grant types are enabled to a given application. This functionality is provided via the management console of the API Manager. Given below are the steps required

1. App developers should have the required permission in order to restrict the grant types available for an application. Permission given below should be set to a user role associate to the App developer.

2. Once this is done please log out and log into the API Manager's admin console

3. Now you would see the OAuth URL available in the left navigation, click on this.

4. Here you would see all the applications that are created by the App developer, from this menu select the relevant application to which the grant types should be restricted.

5. Once you are inside the selected application you can define which grant types should be allowed to a given application. By default all grant types are 'un-checked' and all grant types are allowed. If you want to override this default configuration select on the required grant types that should be allowed to a given application.

6. Once you are done click on the update button and the configuration would be updated.

IP based filtering for Proxy services exposed by WSO2 ESB

WSO2 ESB provides the ability to filter messages based on different parameters. These parameters include data in the message header, message content or even data relating to the message sender. This blog looks into how WSO2 ESB can be used to filter a message based on the IP Address of a client. The below ESB configuration would filter a message and send it to the beackend service only if it arrives from a pre-defined IP address range (192.168.1.*). If the message is recieved from any other IP address the message is dropped. This type of IP based filtering can be applied to secure a backend service from unauthorized access.


<proxy name="IpFilteringProxy"
          transports="https http"
          startOnLoad="true"
          trace="disable">
      <description/>
      <target>
         <inSequence>
            <log level="full">
               <property name="TO Property" expression="get-property('axis2','REMOTE_ADDR')"/>
            </log>
            <filter source="get-property('axis2','REMOTE_ADDR')" regex="192\.168\.1.*">
               <then>
                  <send>
                     <endpoint>
                        <address uri="http://localhost:9000/services/SimpleStockQuoteService"/>
                     </endpoint>
                  </send>
               </then>
               <else>
                  <drop/>
               </else>
            </filter>
         </inSequence>
         <outSequence>
            <send/>
         </outSequence>
         <faultSequence/>
      </target>
   </proxy>

How to retrieve token information using REST API in WSO2 API Manager

WSO2 API Manager provides a host of REST API's that are capable of performing many operations in the API Manager. Given below are the steps to follow to retrieve token information such as the Consumer Key,Consumer Secret, and Access Token using the REST API. In order to perform this we assume that an instance of the API Manager is running(in port offset 0) and an application is already available in the API Store.

1. Initially you need to login to the API Store and create a cookie that can be used in subsequent REST calls. Login to the store using the following command. Replace the username and the password with the relavent values
curl -X POST -c cookies http://localhost:9763/store/site/blocks/user/login/ajax/login.jag -d "action=login&username=xxxx&password=xxxx"

2. Call the Generate Application Key API that would generate the required access keys. Use the below command to generate the application keys. The following command would generate keys for the default applications. Change the parameters accordingly based on your application.
curl -X POST -b cookies http://localhost:9763/store/site/blocks/subscription/subscription-add/ajax/subscription-add.jag -d "action=generateApplicationKey&application=DefaultApplication&keytype=PRODUCTION&provider=&tier=&version=&callbackUrl=&authorizedDomains="

Secure, Expose and Manage a SOAP Service using WSO2 API Manager and WSO2 ESB.

WSO2 API Manager provides support for both REST and SOAP based web services. However the API Manager doesn’t support WS Standards. The API Manager and the WSO2 ESB can be used in conjunction to support WS Standards to API’s exposed via the API Manager. In this blog we look at how WSO2 API Manager can be used with the WSO2 ESB to secure and expose a SOAP based API.

Given below is a diagram depicting the message flow on how WS-Security is implemented using WSO2 API manager and WSO2 ESB.

The message from the client would be encrypted using the public key of the ESB. The encrypted message would be sent along with the acquired OAuth token to the API Manager. The API Manager would validate the OAuth token and enforce throttling on the message. The API Manager would send the encrypted message to the ESB. The ESB would decrypt the content of the message using its own private key and send the request to the backend service.

Once the response is received from the backend service, the ESB would encrypt the message using client’s public key and send it to the API Manager. The API Manager would pass-through the message back to the client. The client would decrypt the message using its own private key.

This type of a scenario is useful in a case where

1.WS-Security needs to be enforced but cannot be enforced directly at the backend service (hence needs be enforced in an intermediary stage in the message flow).

2. Client should be provided with a portal to explore and subscribe to API’s.

3. API Publisher wants to manage life-cycle and manage API versioning of the exposed API’s.

4. Throttling and other security mechanisms has to be enforced on-top of WS-Security.

5. Statistics on API invocations needs to be gathered.