Re: [GSOC] Issues with JAXB at GData binding

[Raymond Feng]

Hi,

The main issue here is that we don't know how to handle the databinding for 
the GData. My wide guess is that the pass-by-value interceptor is triggered 
to copy the data to enforce the PBV semantics for the remotable interface.

Here are a few things you can do to avoid this:

1) Have the GDataBinding invoker to implement DataExchangeSemantics SPI and 
return true for the allowsPassByReference() method.
2) Add a new databinding for GData so that Tuscany knows about GData and 
handles the copy, marshal/unmarshal of the data correctly.

Please point me to the code so that I can give you more suggestions.

Thanks,
Raymond

--------------------------------------------------
From: "Douglas Leite" <[EMAIL PROTECTED]>
Sent: Tuesday, June 17, 2008 7:02 PM
To: "Tuscany-Developers" <dev@tuscany.apache.org>
Subject: [GSOC] Issues with JAXB at GData binding

I have started to implement the invokers at binding-gdata module. Maybe, 
the
simplest operation is retrieve a feed from an specific URI. So, I have
chosen the getFeed() method as the first one to be implemented.

Trying to think as simple as possible, and using the gdata java client, 
the
method follow these steps:

1) Set the user credentials;
2) Get the feed at an URI as a com.google.gdata.data.Feed object;
3) Pass the feed object to the body of the message object
(org.apache.tuscany.sca.invocation.Message);

The following piece of code demonstrate it:
*
    //FIXME - Get credentials automatically
    myService.setUserCredentials("[EMAIL PROTECTED]", "gsoc2008");

    Feed feed = (Feed) myService.getFeed(new URL(uri), Feed.class);

    msg.setBody(feed);*

However, I am having some issues with marshalling/unmarshalling the Feed
object while passing it to the message body. I got these output:

Exception in thread "main" java.lang.IllegalArgumentException:
com.sun.xml.bind.v2.runtime.IllegalAnnotationsException: 3 counts of
IllegalAnnotationExceptions
com.google.gdata.data.BaseFeed does not have a no-arg default constructor.
   this problem is related to the following location:
       at com.google.gdata.data.BaseFeed
       at com.google.gdata.data.Feed
com.google.gdata.client.Service$GDataRequestFactory is an interface, and
JAXB can't handle interfaces.
   this problem is related to the following location:
       at com.google.gdata.client.Service$GDataRequestFactory
       at public com.google.gdata.client.Service$GDataRequestFactory
com.google.gdata.client.Service.getRequestFactory()
       at com.google.gdata.client.Service
       at public com.google.gdata.client.Service
com.google.gdata.data.BaseEntry.getService()
       at com.google.gdata.data.BaseEntry
       at public java.util.List 
com.google.gdata.data.BaseFeed.getEntries()
       at com.google.gdata.data.BaseFeed
       at com.google.gdata.data.Feed
com.google.gdata.client.Service$GDataRequestFactory does not have a no-arg
default constructor.
   this problem is related to the following location:
       at com.google.gdata.client.Service$GDataRequestFactory
       at public com.google.gdata.client.Service$GDataRequestFactory
com.google.gdata.client.Service.getRequestFactory()
       at com.google.gdata.client.Service
       at public com.google.gdata.client.Service
com.google.gdata.data.BaseEntry.getService()
       at com.google.gdata.data.BaseEntry
       at public java.util.List 
com.google.gdata.data.BaseFeed.getEntries()
       at com.google.gdata.data.BaseFeed
       at com.google.gdata.data.Feed
       . . .

BaseFeed is a super type of Feed, and although it does not have a no-arg
default constructor, the Feed has one.

Thoughts?

--
Douglas Siqueira Leite
Computer Science Master's degree student of University of Campinas 
(Unicamp)