Eran Chinthaka wrote:



hi,

doesn't it mean that XML will be parsed twice or events replayed
(PullParser pp = messageContext.getSOAPEnvelope().getPullParser())  and
original OM tree that was first built is then discarded (first built by
StAXSOAPModelBuilder but without DOM then again by StAXSOAPModelBuilder
but with DOM)?

i think there is a better solution: if it is detected that that one of
modules/handlers requires DOM (described in its metadtaa) then why not
to use builder/factory that will produce OM classes that implement DOM
interfaces from beginning?



Yeah, this is the nice picture we like to see, which may not be the actual picture.

We create the builder within the transport. So do u want to expect the
transport to find the correct builder and assign ?


yes if possible - just by knowing path (servlet/service/SecureFoo) you know quite a bit ..

if not possible to determine it then at later stage XML tree must be rebuilt - but that should be the last resort

And take this example. We know that there is a service in our Axis Server,
which security is optional. Meaning messages may come with or without
encrypted. So when a message comes to the service how can the transport
know, whether the message is encrypted or not. If he knows that, yes we have
the nice cute picture u mentioned ;).


i think in this case having factory to build OM with DOM is still preferable to having rebuilding DOM tree - DOM impact should be primarily memory if you use only OM interfaces

So that's the reason behind us treating the message as a usual one
initially, and if the domain specific handler, like wsse handler, detects
what to do he can follow the proposal put forward by Ruchith.


i think it is very serious flaw in your design that will have very negative impact on AXIS2 memory usage and performance - hopefully it is not going to be come as problematic as AXIS1 switching between DOM, SAAJ, and SAX event stream when in worst case it reparsed input for each representation (hmm i start to forget details and maybe that is good sign that i no longer remember that ...)

best,

alek


Ruchith Fernando wrote:



Hi All,

In implementing WS-Security capabilities on Axis 2.0 we will have to
convert the OM to DOM and provide the complete SOAPEnvelope as a DOM
implementation.
The following changes and additions are proposed to the OM
implementation to support this.

1.) The org.w3c.dom.* interfaces will be implemented extending the OM
Impls. (org.apache.axis.dom.*)
Also there will be an implementation of org.apache.axis.soap.*
interfaces extending from the DOMImpls. (org.apache.axis.dom.soap.*)
In this situation we will have to change some of the method names in
the OM interfaces. E.g.: getNextSibling, getPreviousSibling in OMNode

2.) A DOMSOAPFactory implementing the SOAPFactory will be introduced
to provide the DOM_SOAP impls. to the StAXSOAPModelBuilder

3.) How to switch the builder when the security related handlers takes


over:


Since the security handlers depend on the DOM interfaces, they  cannot
work with pure OM instances. They expect DOM impls. So now there's a
need to switch from normal OM factory to DOM factory. Therefore
following method is proposed to to handle this.

There will be some processing of the SOAPEnvelope before it reaches
the security handlers.
And there will be a reference to this partially built SOAPEnvelope in
the MessageContext object. This SOAPEnvelope consists only of pure OM
based elements (org.apache.axis.soap.*). Now we get the pull parser


from the SOAPEvelope we have through the OMStAXWrapper (This is used


to get the pull events from OMElements, irrespectiveof their build
state)

PullParser pp = messageContext.getSOAPEnvelope().getPullParser()
//Returns a pp pointing to the start of the document

Then we create a new StAXSOAPModelBuilder passing the DOMSOAPFactory
together with the pull parser returned from the SOAPEnvelope.

StAXSOAPModelBuilder builder = new StAXSOAPModelBuilder(pp, new


DOMFactory())


At this point the SOAPEnvelope reference in the message context is
pointing to the older pure OM based SOAPEnvelope.
This will have to reassigned to the new OM+DOM based SOAPEnvelope, as
shown below:

messageContext.setEnvelope(builder.getDocumentElement()); // This will
set the reference to the new DOMSOAPEnvelopeImpl

Therefore to achieve this we need to have remember the following point
as a best practise : DON'T POINT TO THE SOAP ENVELOPE OF A MESSAGE,
JUST POINT TO THE MESSAGE_CONTEXT ONLY.

I think this is one of the best use cases which shows the beauty of
the Factory and Builder concept used in Axis2 - OM design :)

Thanks,
Ruchith





--
The best way to predict the future is to invent it - Alan Kay










--
The best way to predict the future is to invent it - Alan Kay



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