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From "Paul Brown" <paulrbr...@gmail.com>
Subject Re: are we really gonna end up with 1 engine anyway?
Date Mon, 20 Feb 2006 18:22:09 GMT
Hi, James --

> Right now today the Sybase code is geared more towards being a
> generic orchestration/workflow engine that today supports BPEL 1.1
> and can support other orchestration/workflow languages and could be
> ported to 2.0 without huge amounts of effort. PXE is specifically
> geared towards BPEL 2.0 as its primary design which could well be a
> good thing if you want a BPEL 2.0 engine - though I do find the PXE
> code harder go grok  - but maybe that's because its more BPEL 2.0
> specific.

I think that there are a couple of points here:

1) Without some guidance, PXE code is more difficult to grok, but once
you're into it, it can be impressively productive.  (For example, you
can change-out the way that the engine implements BPEL in about a week
of effort.  We did this multiple times as the spec changed.)

2) The Jacob virtual machine is a generic durable continuation engine
suitable for many purposes.  I don't know if the prime sieve example
made it into the Subversion tree, but that would be one place to grok
what's going on.

3) PXE actually runs both 1.1 and 2.0 against the *same* runtime; only
the compiler is different...  You could also, within reason, set up
variants of each if you wanted to have compatibility with other
engines that made tradeoffs with areas of ambiguity in the BPEL4WS 1.1
spec.  This means that you can do lots of cool things...  For example,
if you had the same set of ports and port types, you could run
*different* versions of a process in the same pool of instances;
they're just differen expressions to be reduced but with the same
"free" symbols.

4) The current JBI integration is less than ideal, as it doesn't fully
replace PXE's internal JBI-like messaging framework with the JBI
equivalent.  This has its moments (PXE is WSDL 1.1-biased, JBI is WSDL
2.0-biased), but it would be doable if there was motivation.

#4 is something that we should address.

I'll let Bill or someone else from the Sybase side talk about how BPE
works, but it's my initial impression that it's at a higher level.

You  should find a way to get a JaCOb overview from Maciej and then
make a fresh assessment.

-- Paul

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