On 02/24/2011 05:54 AM, Thomas Heute wrote:

Nick, Julien, Alain,

As said before we'd like to harmonize the XML parsing accross the GateIn projects. Let's kill this once for all...

It doesn't mean we would change the existing parsers overnight but it means we will impose a way for any new parsing (or when we decide to rewrite a parser).

If we need parser tools, they will go in Common module ultimately. There might be a phase when the code will be duplicated (as Nick's tools need to work on an untouched portal where upgrading common is not an option).

We already agreed that StAX as a base was the way to go, I hope we still agree ;)

I think we're in agreement that StAX is the way to go if we're focusing on pure performance.


Let's separate in reading/writing XML (doesn't necessarily necessarily mean marhalling/unmarshalling BTW) and agree on both.

Reading XML:
    Option 1:
        Plain StAX, JBoss AS 7 uses that (in fact they use StAX Mapper, a very lightweight library made by the JBoss AS7 team. https://github.com/jbossas/staxmapper/ which only helps to work with multiple namespaces + some little helpers for ignoring part of the file, format the XML when writing...)
        One example of JBoss AS 7 parsing file: https://github.com/emuckenhuber/jboss-as/blob/master/web/src/main/java/org/jboss/as/web/WebSubsystemParser.java

Since we've already invested some time to write some code around stax, I think we agree on something that will benefit GateIn.

    Option 2:
        Nick's stuff (please explain advantages/drawbacks)

The API isn't quite intuitive.  Once you get used to it, it's fairly easy to write and maintain.  A lot of the use cases that stax-builder provided (reading wise) I think are supported in staxnav, which has a simplified API.  I'm good scratching this (reader part) especially if we can solve the issue I mention below about staxnav.

    Option 3:
        Julien/Alain's stuff (please explain advantages/drawbacks)

API is nice to use, makes sense for most xml parsing.  One issue I have is that it does save content in memory, even after navigation is successful.  I propose we discard all history after a successful navigation.  I'll look into a solution for this.


Writing XML:
    Option 1:
        Plain StAX (well-formed guaranteed over plain Writer)
    Option 2:
        Nick's stuff (please explain advantages/drawbacks)

Has formatting writer, can chain writes, easy to use.

    Option 3:
        Julien/Alain's stuff (please explain advantages/drawbacks)

No writing capabilities.

Note that there are other utilities and frameworks based on StAX:
    Stax-Utils: http://stax-utils.dev.java.net/
    StaxMate: http://wiki.fasterxml.com/StaxMateHome
    Apache Axiom: http://ws.apache.org/commons/axiom/
   
Thomas

So to summarize, I am leaning towards combining these efforts as we've previously mentioned as long as we don't introduce any performance or maintenance issues as opposed to using plain stax.

- Nick