You are viewing an old version of this page. View the current version.

Compare with Current View Page History

« Previous Version 5 Next »

Project

Implementing XMLSchema XS:Override specification

 

Student Name

Udayanga Wickrmasinghe

 

Email

mastershield2007@gmail.com

 

TimeZone

GMT +5.30

 

Abstract

  • Apache Xerces2-J consists of a set of standards compliant XML parsers and a [1] fully conforming XML Schema processor which are built on top of a complete framework(XNI) for building parser components and configurations that is extremely modular. Although Xerces XML Schema processor supports more than the minimal requirement under W3C XML Schema 1.1 [2] specification some vital schema component support is still to be realized. This project tries to implement one such requirement, namely xs:override support for XML Schema1.1 .

Description

  • XML schema specification version 1.1 specifies syntax and semantics of “Overriding component definitions<override>”[3] or xs:override under “Schemas and Namespaces: Access and Composition” . The new component definition is a powerful addition to the XML schema composition framework which tries to mitigate some of the constraints present in similar constructs such as xs:redefine or <redefine> schema components. The <redefine> construct defined in “Including modified component definitions (<redefine>) “[4] is useful in schema evolution and versioning. It is useful only when there exists some restriction or extension relation between the old component and the new redefined component. But there are occasions when the schema author simply wants to replace old components with new ones without any constraint. Also, existing XSD processors have implemented conflicting and non-interoperable interpretations of <redefine>. And to add to the trouble <redefine> construct is declared ·deprecated· in XML Schema 1.1 [2]. Hence as mentioned in the beginning , <override> construct tries to avoid these bottlenecks and allow unconstrained replacement as and when needed.

Things I have Done So far

  • Since this project is about implementing a XMLSchema 1.1 specification construct , I had to go through this specification docs several times to understand the exact structure and semantics of the component I’m going to implement which I think is of vital importance when it comes to the design n implementation. Previous discussions (that has happened in Xerces-j-dev mail archives) about this xs:override support , online articles and tutorials also helped a lot in this cause. I also interacted with Xerces mailing list (especially with my mentor) to clarify critical points and implementation details. Since knowing Xerces and it’s internal framework(XNI) is obviously essential for the implementation I had to dig into various documentation, API information ,samples regarding Xerces Design,architecture and especially XML schema processing. I did download source code of Xerces2-j from trunk and build the code inorder to try and test out some samples to get a hang on the flow of things related to schema loading and processing.

Development Schedule

Time Schedule/Duration

Activity

March 18 - March 29

 

March 29 - April 9

 

April 26

 

April 26 - May 24(Community Bonding Period)

 

Interim Period

 

May 24 - July 12

 

 

 

 

 

Deliverables

  • Source/patch related to xs:override implementation
  • * Solid set of test cases to verify related aspects of xs:override schema composition
  • Documentation (java docs + design details) on xs:override implementation/API

About me

  • I'm a Computer Science Engineering undergraduate (final year),of the department of Computer Science and Engineering, University of Moratuwa, Sri Lanka . I'm very much passionate about Computer science and am especially interested in subject areas related to Compiler Theory ,Distributed Systems and Enterprise Middelware and also Artificial Intelligence.

  • I do have experience in open source development and related aspects and always loved working in such a dynamic and encouraging environment . I have worked on projects related to Apache Axis2 where I developed a tool [5](incubating) to extract WS-Policy(ie:-Security Policy) from WS policy compliant SOAP messages which is especially useful in scenarios such as for clients who wish to build compatible policy for Services which don’t expose their messaging policy explicitly. This gave me a great understanding on WS:Security specifications and on mechanisms used by security modules such as Apache Rampart as well. Furthermore i developed Axis2 Messaging and Service Level Infrastructure for Rubyscript [6], so that Ruby Scripts can be exposed and accessed via [WebServices] by clients . I also do have experience involved in projects related to Eclipse plugins, OSGi , XML parsers(this for our internal module DSD2.0[7] parser) and Data Mining (ie:-Collaborative Filtering), which got me working in wide variety of programming/scripting languages such as Java ,C,C++, Javascript,Ruby,etc and under various platforms of Linux and Windows. I am currently involved in implementing a [TupleSpace] based Distributed System framework(which runs on top of a DHT[distributed hash table] named [FreePastry] [opensource implementation of Microsoft Pastry]) for our final year project ,which facilitates time and space decoupling as well as content based addressing for messages in a distributed environment [8]. I consider my self a motivated computer science enthusiast who is willing to self learn and accept challenges and achieve them to the best of my ability.

  • No labels