[jboss-as7-dev] DMR GWT Prototype

[Jason T. Greene]

I was able to port DMR so that it can be used with GWT to send and 
receive DMR's native externalized binary format via client-side javascript.

https://github.com/n1hility/jboss-as/tree/detyped2

A pure binary protocol is not possible in all browsers, so the 
implementation has to base64 encode the stream.

The main advantage to this approach is that there is essentially no loss 
of information (all type info is preserved), and the API works very well 
at dynamic access and is exactly the same as the management API used in 
server code. In addition parsing requests on the server is much more 
efficient since there is less transformation and pattern matching. 
Lastly it has the potential to be much more space efficient.

However, due to Javascript's very poor binary handling, lack of 
streaming, and lack of native floating point encoding, client side 
execution is on average 2x+ slower than directly evaling JSON code. That 
said, processing a dump of the entire model took on average 9ms (in 
webkit based browsers), and in the worst case (firefox) took 20ms. So 
the times are still somewhat reasonable.

In addition to being faster on the client side, eval'd JSON does not 
require maintaining the DMR API. On the other hand JSON usage in GWT is 
clumsy if you aren't using overlay types, and overlay types are not 
helpful to dynamic client code (dynamic as in being able to discover and 
manage resources based on resource descriptions as opposed to static code).

Lastly, JSON output, by its nature, loses type information. Although 
this could be worked around if it's a problem by adding type identifiers 
to all node values, at the cost of looking less JSON like (extra verbose).

So ultimately it's up to everyone working on the console as to which 
direction this goes. I can easily support both mechanisms on the server.

-- 
Jason T. Greene
JBoss, a division of Red Hat