Exposing an Axis1 service through WSO2 WSAS

Do you want to make use of the powerful QOS features of Axis2 with your legacy Axis1 applications? Yes it is possible with WSO2 Web services application server. It allows easy deployment of any Apache Axis1-based Web service and engage advanced WS-* services, such as WS-RM and WS-Policy in front of legacy Axis1 services.
Lets see how we can use this cool feature.

Step 1

Write the service impl class.

package org.wso2.wsas.service;

public class Calculator{

public int addition(int x, int y){
return x+y;
}

public int multiplication(int a, int b){
return a*b;
}

public int subtraction(int c, int d){
return c-d;
}

public double division(double m, double n){
return m/n;
}
}

Compile and make a jar with the above class. Suppose it is Axis1resources.jar

Step 2

Write the deployment descriptor (*.wsdd) for your service impl class and save it as calculator.wsdd

<deployment xmlns="http://xml.apache.org/axis/wsdd/"
xmlns:java="http://xml.apache.org/axis/wsdd/providers/java">
<service name="Axis1calculator" style="wrapped">
<parameter name="className" value="org.wso2.wsas.service.Calculator"/>
<parameter name="allowedMethods" value="*"/>
</service>
</deployment>

Step 3

Start WSO2 WSAS (If you haven't downloaded it yet, get it from http://wso2.org/projects/wsas/java

Access WSO2 WSAS management console using https://localhost:9443 (Default admin user credentials are admin/admin)

Go to Services and service group management page and click on "Upload Axis1 service" link. You will be directed to the following page



Browse for the above calculator.wsdd and Axis1resources.jar and click on Upload. Axis1 service will be deployed on WSAS and you will get a confirmation message.

Step 4

If the deployment is successful, you will see the Axis1 service is shown in the services and service group management page.
Click on "Axis1calculator" service.
In the "Service Management" page, select "Tryit"
Invoke service using some inputs and see the output.

HTTP Compression

I wasn't much aware of HTTP compression though I heard the term often. Thanks to a nice article written by Martin Brown, I was able to get a basic understanding as well as how to get Apache and IIS servers configured to use HTTP compression.
HTTP compression is an mechanism to utilize the available bandwidth effectively. HTTP protocol data is compressed before it is sent from the server. No specific configuration is required at the client side and server configuration is also relatively simple.
If you are involved in web performance testing, It would be worthwhile to get some knowledge on HTTP compression.

Weblogic application classloading

We wanted to use our own stax parser implementation in a web application deployed on Weblogic 9.2. The user guides and BEA forums suggested two approaches.

1. Using weblogic.xml web application deployment descriptor with <prefer-web-inf-classes> element. Setting this to true allows a Web application to use our own version of a third-party class

2. Using filtering classloader
Here we are allowed to explicitly specify packages which are required to be loaded from the application. These packages can be listed in weblogic-application.xml

I tried both approaches separately in order to use wstx-asl-3.2.1.jar shipped with our application instead of loading weblogic stax parser.

Unfortunately, both class loading mechanisms failed to pick up our stax parser :(

We even tried to hack weblogic.jar by editing property files which tightly map the parser interface to the impl*. We extracted weblogic.jar and edited the stax impl class entries (i.e:- com.ctc.wstx.sax.WstxSAXParserFactory) of the following 4 files included in META-INF/services directory.
javax.xml.parsers.SAXParserFactory
javax.xml.stream.XMLEventFactory
javax.xml.stream.XMLInputFactory
javax.xml.stream.XMLOutputFactory

However, weblogic reported version conflicting issue when restarting server with the edited weblogic.jar.
I did not encounter these class loading problems with JBoss or tomcat. I'm uncertain about why it is such a pain in configuring a commercial product like Weblogic to use application specific packages.

Gartner lists wso2 as a cool vendor in web technologies

WSO2 has been chosen as a cool vendor in web technologies by Gartner. More information can be found at Pauls' blog

Axis2 session management - Transport session

Apache Axis2 provides session handling capability using 4 session scopes; request, soapsession, transport and application. I have already blogged about application scope a few months ago.

Axis2 transportsession uses transport level session management techniques to manage sessions of a Web service. Life time of a session is governed by the underlined transport, not by Axis2 itself. If a service is deployed in a transportsession scope, then, there will be service instances for each of the transport session.

You can read my recent Knowledge base post on how to manage sessions with transport session scope here at wso2 oxygen tank.

Data services and mediating SOAP messages with Synapse DBReport mediator

Apache Synapse is an ESB that has been designed to be simple to configure, very fast, and effective at solving many integration and gatewaying problems. It comes with a set of ready-to-use transports and mediators.
Visit Apache synapse web for more information about message mediation.

WSO2 data services is a convenient mechanism to provide a Web service interface for data stored in some data source. Data sources such as relational databases, CSV files & MS-Excel files can be easily service enabled using Data Services.
You can find more details about WSO2 Data services from here

I got a lot of positive feedback about my previous posts (securing web services) since they helped beginners to understand and experiment with simple examples without digging in to complex details.
I thought to describe a simple scenario which demonstrates the usage of data services and synapse together. I hope the following step-by-step instructions will help most of the novice users to get started with WSO2 data services and Apache synapse in a fairly simple manner.

I am going to use the following open source software tools in this demonstration. So, please make sure you have configured them in your environment.

Apache Synapse 1.1.1 (Download)
WSO2 WSAS 2.2.1 (Download)
Apache derby 10.3.2.1 (Download)
Apache JMeter (Download)

Scenario:
A SOAP request will be sent to WSO2 WSAS to get the net salary of an employee which resides in a database. The messages will be transferred via synapse. The response SOAP message will be subjected to mediation by synapse DBreport mediator. In which, the net salary of a different employee will be updated by evaluating the net salary of the requested employee. In other words, we will get the net salary of employee A and instruct synapse to update employee B's net salary to the net salary of employee A.

Step 1

Database preparation

We should prepare the necessary database and tables as the first step. Apache derby will be used in this example.

• Start derby network server

Go to derby_home/bin and run startNetworkServer.bat

• Create a database

start ij utility (derby_home/bin/ij.bat) and enter the following command.
CONNECT 'jdbc:derby://localhost:1527/employeedb;user=wsas;password=wsas;create=true';

• Create a table and insert data

create table employee(name varchar(10), empid varchar(10), netsalary double);
insert into employee values ('Sean','1',1000.00);
insert into employee values ('John','1',3000.00);
insert into employee values ('David','1',2000.00);

Next, I'm going to create a data service using the above data source. Data services allow users to expose the relational data as web services so that they can be accessed and manipulated in programming language independent manner.

Step 2

Create a data service

Please make sure the derby client driver is available in your WSAS instance. Copy derby_home/lib/derbyclient.jar to WSAS_HOME/lib.

Install WSO2 WSAS if it is not already installed. start WSO2 WSAS using WSAS_HOME/bin/wso2wsas.bat

Access WSAS management console (https://localhost:9443) where we can configure our data service through UI.

Go to 'Services and service group management' page and click on 'Define data service' link. You will get a page as given below.


Enter 'Synapsedataservice' as the service name. Select 'RDBMS' as the data source. A pop-up window will be displayed where we can configure data base details.
Driver Class = org.apache.derby.jdbc.ClientDriver
JDBC URL = jdbc:derby://localhost:1527/employeedb
user name= wsas
password = wsas

Click on the 'Next' after configuring data source details. The second step of the data service configuration will be displayed. Click on 'New query' button. The following pop-up window will appear.


Enter the following details in the above window.

Query ID=Empsal
SQL Statement = select * from employee where name = ?


Click on ' add new input mapping' and enter followings.

Name=name
sqlType=STRING

Grouped by element = employees
Row name = employee

Click on 'add new Output mapping' and enter the following values.
Mapping Type = element
Output field name = name, SQL column Name = name
Output field name = empid, SQL column Name = empid
Output field name = netsalary, SQL column Name = netsalary

After entering all of the above values, click 'Next' button in the data service - step 2.

Step 3 of the wizard will be displayed. Click on 'Add new operation' button and enter the following values.
Operation Name = EmpSalOp
Query= Empsal

Click 'Finish' to deploy the data service.

Step 3

Test the data service

You can test your data service simply by invoking it in RESTful manner. Issue the following url.
http://localhost:9762/services/Synapsedataservice/EmpSalOp?name=Sean

You should get the details of employee, Sean.

<datas2:employees>
<datas2:employee>
<datas2:name>Sean</datas2:name>
<datas2:empid>1</datas2:empid>
<datas2:netsalary>1000.0</datas2:netsalary>
</datas2:employee>
</datas2:employees>

You should observe the simplicity of exposing relational data using WSO2 Data services. Lets see how we can use Apache Synapse to do some mediation in messages passing through it.

Step 4

Creating Synapse configuration

Install Synapse1.1.1 (just unzip the binary distribution). Synapse provides a xml configuration file to define the mediation rules using synpase configuration language. Open Synapse_home/repository/conf/synapse.xml.

Remove the existing contents of that file and add the following configuration.

<definitions xmlns="http://ws.apache.org/ns/synapse">
<sequence name="main">
<in>
<send>
<endpoint>
<address uri="http://localhost:9762/services/Synapsedataservice"/>
</endpoint>
</send>
</in>
<out>
<log level="custom">
<property name="text"
value="** Reporting to the Database **"/>
</log>
<dbreport>
<connection>
<pool>
<driver>org.apache.derby.jdbc.ClientDriver</driver>
<url>jdbc:derby://localhost:1527/employeedb;create=false</url>
<user>wsas</user>
<password>wsas</password>
</pool>
</connection>
<statement>
<sqlupdate employee set netsalary=? where name='John'</sql>
<parameter expression="//datas2:employees/datas2:employee/datas2:netsalary"
xmlns:datas2="http://ws.wso2.org/dataservice" type="DOUBLE"/>

</statement>
</dbreport>
<send/>
</out>
</sequence>
</definitions>

Here, the request message pass through synapse will be directed to the data service endpoint without doing any mediation. It is defined in the <in/> element.
The SOAP response will be transferred via two different mediators.

Log - when the soap response reaches synapse, it just logs the message as defined.
dbreport - writes information to a Database, using the specified insert SQL statement.

In this configuration, we evaluate the response SOAP message using an XPath expression and get the net salary of the employee. Then we update the net salary of employee John with that.

Now you can start synapse with the above configuration by running synapse.bat.

To see how this works, we need to send a SOAP request message to Synapse. Apache Jmeter can easily be used to transmit a soap message.

Step 5

Test message mediation

Install jmeter in your system (Just unzip jmeter binary distribution). Run jmeter.bat.
Create a thread group and add SOAP/XML-RPC request sampler. (Please read http://wso2.org/library/1085 if you are not familiar with testing web services using Jmeter)

Add the following soap request in to the SOAP/XML-RPC data section.

<soapenv:envelope soapenv="http://schemas.xmlsoap.org/soap/envelope/">
<soapenv:body>
<axis2ns5:empsalop axis2ns5="http://ws.wso2.org/dataservice">
<name>Sean</name>
</axis2ns5:empsalop>
</soapenv:body>
</soapenv:envelope>

You may have wondered how I captured the above request Soap message. There are several different approaches.
1. write a java client and invoke the data service. Capture the message using apache Tcpmon
2. Enable Soap Tracing in the WSAS management console. As we did above, invoke the service in RestFul manner. Then access the SoapTracer in WSAS management console and copy the soap request. (This will be the easiest method)

Enter 'http://localhost:8080' as the URL in SOAP/XML-RPC request.
Enable 'Send SoapAction' and enter 'urn:EmpSalOp'

If everything is correct, you should see the following in your Jmeter console.



Run the sampler. You may check the synapse console where you can monitor the message mediation.

Lets see whether the net salary of John is updated as expected. Open the ij utility of Derby and issue the following SQL statement.
select * from employee;

You should notice that the net salary of John and Sean are same.

In this post, we looked at the WSO2 data services and Apache Synapse using a simple scenario. You will be able to improve the above scenario by applying more mediation rules.

Software is easy to make, except when you want it to do something new

Excellent article which describes the lessons learnt from Chandler project.

http://gamearchitect.net/Articles/SoftwareIsHard.html