Not the first time...ΒΆ

date:2003-12-13 19:23:53
category:The Lure of XML

From an email I got recently, lightly edited. Responses to follow.

Problem: The data layer of application architecture must be flexible enough to adapt to virtually any new data-driven functional requirement demanded by today’s client..right...well to support such adaptability in client deployments, the data model must allow almost arbitrary categorizations and groupings of data within the system without hindering development speed, system response time, ease of use and system simplicity.

Proposed Architecture: I am really started to take a liking to Java/XSLT that is driven by XML...well here is my thinking:

  1. Client requests can easily be transformed into client-independent XML structures
  2. EAI tools or APIs could handle both receiving and transmitting events via XML
  3. SQL result sets can possibly be naturally modeled as XML fragments
  4. The XML tree fragments returned from the API and database queries may be used to generate dynamic queries.
  5. Client side response should first be represented as XML to capture the data structure. Of course this XML could be converted to whatever format required by the client

Benefits:

  1. Both data and events are naturally modeled in a similar structure: XML
  2. A single tool, XSLT, is able to transform and generate both data and events
  3. Using a standard XML format for both incoming client requests and outgoing response allow clean client independence.

Weaknesses:

  1. No interactive debugging tools. However this could be mitigated by extensive debug logging by the application server.
  2. XSLT is a recursive functional language and requires you to adapt a new methodology other than object oriented.
  3. Abstraction hurdles would not be enforced by the interpreter but possibly with superb coding discipline.

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