[mapguide-trac] #972: Failing operation when accessing 2.1 server with 2.0 client

[MapGuide Open Source]

#972: Failing operation when accessing 2.1 server with 2.0 client
---------------------------+------------------------------------------------
 Reporter:  uvlite         |         Owner:       
     Type:  defect         |        Status:  new  
 Priority:  low            |     Milestone:       
Component:  Server         |       Version:  2.1.0
 Severity:  minor          |    Resolution:       
 Keywords:  compatibility  |   External_id:       
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Comment (by ksgeograf):

 The problem here is not the client, but the mixing of webtier and server
 versions. You cannot mix the two. They are in seperate MSI packages
 because you can install them on different machines if you like.

 Studio has no effect on this.

 The problem occurs because the binary objects only exist in the current
 version, and the binary objects are serialized/deserialized using their
 current format. If you send a 2.0 object into the 2.1 server, there is no
 logical way of handling the missing fields, especially if the object is
 later sent back from 2.1 to 2.0.

 The current serialize/deserialize methods works by manually crafted code
 in each class. This gives the greates flexibility but also removes any
 chance that this could be automated, or centrally handle version
 differences. This means that the binary objects are heavily tied to the
 version being used. Managing multiple binary versions would have a rather
 large overhead. To obtain version compatibility, you can rely on the http
 interface, like Maestro and Studio does.

 If you update the webtier you should find that Studio works as expected,
 as it is using the http interface, which correctly handles the different
 versions.

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Ticket URL: <http://trac.osgeo.org/mapguide/ticket/972#comment:2>
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