GSoC: How to integrate with existing code base

This post will contain my arguments on "How to integrate this project to the existing WSF/Jython code base". This is a followup to my last post.

1. Modify the Python deployer to support Contract First approach.

2. To support Contract First approach you need to be able to generate a skeleton and a message receiver for your service. The generic message receiver that I have already written may not work because it works only on a limited schema structure.

3. Another way to look at the above argument(2) may be; only generate the client code and use the existing WSF/Jython's client API. Then before running the client code you can add the WSF/Jython client-side jar to the class path.

The above arguments are my opinion(for now) on integrating the gsoc code to existing code base. The above arguments may subject to change.

GSOC: Problems faced during development

Earlier I said that I would be writing a blog post on the problems which I encountered during the development phase of my GSoC project. Here I am compiling them to a list. Some points in the list may not directly be problems but important things which came across during the process.

1. Had a problem with building axis2. This was overcome when I found a workaround for this. (This was a hard issue to regenerate because this will only happen occasionally.)

2. There were lot of dependencies inside axis2's code generation framework. Some dependencies were not set by the build script. Therefore had to manually add the dependencies and run the code. When it gives a compilation error stating a dependency is not there, had to set the dependencies. This took some time :).

3. Had to take some time to understand the existing code base and the architecture of the code generation framework.

4. Learned to work with XSLTs.

5. Another important point to note is that the WSF/Jython distribution, now needs some additional libraries to successfully run. You may have wondered "why is this happening?". As you may already know WSF/Jython is built on top of Apache Axis2. The new releases of Axis2 are having more dependencies towards other liblaries/jars (eg. wsdl4j, etc). Since I no longer work for WSO2, I do not have the access writes to change the build script for WSF/Jython. As soon as I get there, I would remember to revise the build script. Until then you could do a small workaround:)

Download Axis2 standard binary distribution. Then extract it. Add the jars which are residing in the lib folder, to the classpath. Then you could carry on with your work.

6. How to integrate this project to the existing WSF/Jython development. (I will present my arguments on this on a new post)

Mr. Lakshman Kadiragamar's Lesson

In 2005, almost fifty years after he left Oxford, Mr. Lakshman Kadiragamar's portrait was unveiled at the Oxford Union. This was a great honour bestowed by the Oxford Union on only 15 others in its 183 year history.


Mr Kadirgamar had this to say about that event;

'......I would like to, if I may, to assume that I could share the honour with the people of my country, Sri Lanka . I had my schooling there, my first university was there, I went to Law College there and by the time I came to Oxford as a postgraduate student, well, I was relatively a matured person. Oxford was the icing on the cake … but the cake was baked at home ......(applause) .'

This is indeed true. People appreciate only the icing on the cake not where it was baked first.

Design for Jython Extension for Axis2

In a earlier post I said that I am coming up with a Jython extension for Axis2. This will be a code generation tool for jython. This will use existing infrastructure in Axis2 to support Contract First Web services in Jython. What I am planning to do is to integrate this code generation tool into WSF/Jython. Then WSF/Jython will be able to support both, contract-first and code-first approaches. Thus, making the life easier for the Jython developer :).

The code generation engine calls the extensions one by one and then calls a component what is known as the Emitter. Emitter is the actual component that does the significant bit of work in the code generation process. Emitters are usually language dependent and hence one language has one emitter associated with it. Therefore there should be an emitter to support Jython code generation. This simple yet powerful architecture is shown in the above illustration.

The Emitter processes the WSDL and builds a object model. The object model is simply an XML file which contains the object model of the WSDL with respect to Axis2 information model (ie. axis service, axis operation, axis message, etc). The template is a XSLT file which contains information on how the code should be generated. Then the built object model is parsed against the template to build the jython source code.

wsdl2java Code Generation

Axis2's wsdl2java code generation tool can be used to auto-generate programming language code for a given WSDL file. It can either generate code to invoke a Web service, or it can auto-generate the skeleton code that will adhere to the specification described within the WSDL file so that the generated code can be deployed as a Web service.

$HOME = Small Miracle

My $HOME sweet home - Sri Lanka :).

Axis2 Code Generator

This is a follow up to my earlier post. What I am planning to do is to come up with a mechanism to generate jython code for a given WSDL. For this purpose I am planning to use Axis2's Code Generation module.

When you consider a SOAP processing engine, one of the key value additions will be code generation based on WSDL. It is normally considered as a tool and importance of it can be seen as;

1. User convenience - Code generation tool helps users, to use the framework in easy and efficient way.
2. Make use of the framework to it's full potential.

Now let's have a look at the architecture of Axis2 Code generator.

The tool's architecture is pretty straight forward. The core processes the WSDL and builds a object model. Then the built object model is parsed against the template to build the source code.