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Persistent XML

Case study 75 minutes

Storing XML in a Relational Environment

Andy Doddington

You do not need to be the most perceptive of people to realise that XML and its siblings are somewhat flavour of the month at the moment. However, most examples consider relatively small-scale examples in which the issue of persistence barely exists - in most cases it is simply assumed that the XML will be held in a simple flat file.
By contrast, this case study describes a framework that was developed to allow large volumes of XML to be saved to a relational database, in such a way that the virtues of both technologies are retained. These include flexibility, simplicity and extensibility on the XML side, whilst benefitting from the ubiquity, reliability and performance aspects of relational databases. A further significant benefit of the approach is that it allows ad hoc queries to be performed on the persisted XML data, using standard SQL queries.

Andy Doddington (andy@kndj.freeserve.co.uk)

KNDJ Ltd

In an age in which a person is considered experienced after two years and an expert after three, it is almost embarassing to admit to having been in this industry for over twenty years. Although I started off in the area of image processing, I spent most of this time in the areas of SCADA, data logging and signal analysis - which are actually more fun than they sound. I also enjoyed the dubious pleasure of a few years in project management - before realising that my outlook was more Dilbert than 'Pointy-Head'.

My interest and belief in OO dates back around seven years, during which time I have seen it evolve from being a rather revolutionary idea which was highly likely to provoke Fear Uncertainty and Doubt, to effectively being part of the mainstream of software development - at least in the areas in which I am now involved.

For the past five years or so I have been working in the banking industry, due in part to the large number of charming and intelligent people that exist in this area - oh, and the money helps too. The last three years have been spent working for an investment bank, helping with the development of a new Swaps Trading System. This project was able to demonstrate many of the benefits of OO, including being one of the most enjoyable projects that I have worked on!

IMPORTANT NOTE (BUT I DON'T KNOW WHERE TO PUT IT)

This presentation is based on work that was carried out on behalf of JP Morgan and is produced here by kind permission. However, please note that all views, errors and omissions are purely my own.

Topics

Business Background
Brief overview of XML/XSL
Why use XML?
Why a Relational D/b?
Potential approaches - pros/cons
Chosen Approach (more details)
Technical Overview (design/algorithms)
Simple Examples
Lessons Learned

Benefits

Naturally, I would be pleased to see the described approach being re-used, since I believe that it solves a problem that is likely to become more of an issue as the use of XML increases - which certainly appears to be the case at the moment.

However, my main motive is to demonstrate how the virtues of XML can be used to allow the development of more flexible solutions than those based on traditional hard-wired data structures. In an age in which the cost of software continues to spiral ever-upward, I believe that the idea of built-in flexibility is one of the most powerful weapons that we have at our disposal and one that is greatly enhanced by the use of XML.

Session: Case study 75 minutes Level: intermediate
Audience: People who are interested in XML/XSL and would like to see an example of its use; people who have encountered the problem of persistence with XML; or people would like to see some of the benefits of using XML Max Name a number!

Material

Presentation on slides to be provided. This can be included in conference documentation if required.

Delivery

See above.

Format

See above.

108

Session: Case study 75 minutes	Level: intermediate
Audience: People who are interested in XML/XSL and would like to see an example of its use; people who have encountered the problem of persistence with XML; or people would like to see some of the benefits of using XML	Max Name a number!