[mapguide-internals] Future Development Options for Web Server Extensions and new High Performance Viewer

[carlj]

Having worked quite extensively with MapGuide for the past 2 years I was
hoping to get a discussion going regarding trying to address some of the
pain points of MapGuide Enterprise / Open Source.

Many organisations have had difficulty migrating from MapGuide 6.5 to
enterprise due to difficulties with stability and performance. Rather than
pointing fingers I hope to have a professional discussion of the options for
addressing some of the issues.

One pain point is the MapGuide web server extensions. These are implemented
in native C++ and access to the development platforms such as .Net, Java and
PHP. This is done using SWIG to auto-generate objects in the platforms using
them. 

I want to propose that the use of SWIG should be gradually phased out in
favour of implementing the Web Server extensions in as pure .Net and Java
etc. I had originally discussed trying to port the web server extensions in
their entirety in one go but due to the volume of work involved this could
take a long time. This may still be a long term goal but in the shorter term
converting such things as the value objects and the core communication /
serialization components would be a good starting point. 

There is likely to be resistance to the suggestion of porting as there is
the disadvantage of having to duplicate changes across multiple
implementations. I personally believe that in the long run moving towards
the webserver extensions being implemented in the specific platform of the
website will beneficial in the future. SWIG is known to leak memory if not
used very carefully. Also many developers encounter lot of pain due to not
being able to observe the internal state of the objects with which their
applications interact. Dealing with the library dependencies also causes
pain.

As the Web Server Extensions communicate with the server via TCP/IP then
this seems to me to be a natural application boundary between the MapGuide
server and the Web Server Extensions. All the platforms currently supported
by the web server extensions are able to communicate using TCP/IP. 

There is an added bonus to having Web Server Extensions code ported to Java
and .Net and this is that it could be used as the basis of a new plug-in
based MapGuide viewer to fill the hole left by the unsupported DWF viewer.
The new viewer could be higher performance than even the DWF viewer was able
to be because rather than rendering DWF (meaning the server has to first
package up data as DWF) a new viewer would instead be able to use the ported
Web Server Extensions to directly de-serialize the C++ objects into objects
in Java or .Net. These could then be used to render the map purely on the
client. With all the rendering pushed to the client, the server has much
less load and the overall solution should scale better. As an added bonus
these technologies also offer the possibility of, for the first time,
rendering 3D mapping data in the browser on the client. 

For situations where this viewer would not work the AJAX viewer is still
going to be available. I do not believe that the AJAX viewer could ever be
expected to achieve the performance possible with a plug-in based viewer.

I have already had a discussion about this idea off-line but the suggestion
was to create another C++ based browser plug-in. I am not in favour of using
C++ for a browser plug-in as this would likely mean going back to supporting
one browser on one operating system which goes against why an organisation
would be pushing an application into the web. When using native C++ on the
client then it might as well be a full client application rather than a web
based one. Granted the Viewer API allows some customization via JavaScript
but I would much rather use a plug-in technology which is cross platform and
cross platform. I would favour this even if the performance were somewhat
less than possible in native C++.

There are more points that I could make but I think I would leave it there
for starting a discussion.
 
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