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From Aaron Anderson <aander...@apache.org>
Subject Re: Evolvable OModel
Date Fri, 25 Mar 2011 15:02:46 GMT
Hi Jeff,

I put what I have at https://github.com/aaronanderson/ODE-X

Regards,

Aaron

--- On Fri, 3/25/11, Jeff Yu <jeff.yuchang@gmail.com> wrote:

From: Jeff Yu <jeff.yuchang@gmail.com>
Subject: Re: Evolvable OModel
To: dev@ode.apache.org, aanderson@apache.org
Date: Friday, March 25, 2011, 4:57 AM

Hi Aaron,
I am interested in this work, it would be a great idea that you can put it somewhere on the
github. ;-)
RegardsJeff
On Fri, Mar 25, 2011 at 9:55 AM, Aaron Anderson <aanderson@apache.org> wrote:

Hi Everyone,



Sorry I missed the call earlier this week; due to the daylight savings time change in the
US I set my alarm clock for the wrong hour.



Over the past few months in my spare time I have been working on a prototype of an alternative
BPEL engine architecture. I wasn't planing on sharing anything publicly until the prototype
was fully functional but this conversation touched on one of the concepts I am exploring so
I thought now would be a good time to see if there is any interest in the work I have been
doing.




Based on my experience with contributing to the Apache ODE and HISE projects I noted the following
improvements that I would like to see:



1) Support for modern dependency injection ( including JPA)

2) Ability to run in multiple containers (JavaEE, SCA,

 standalone)

3) Event driven architecture

3) Full support for a container provided JAXWS implementation (instead of requiring AXIS/CFX)

4) First class debugging support

5) Seemless integration of extensions into the engine

6) Retention of all source files (not compiled away)



With these goals in mind I drew up this architecture that I have been working towards:



http://people.apache.org/~aanderson/Runtime.png



In relationship to this conversation, the model I am investigating is similar to Gary's BPEL
based OModel where all artifacts are imported into a repository and a build plan is invoked
to generate an XML based executable, comparable to a set of very high level Java byte code.
For the most part common instructions would be used in the model but where it is needed instructions
from an extension would be inserted. A runtime interpreter would then step through these instructions
using a XML schema namespace ->


 Java instruction implementation mapping to actually execute the process.



As far as progress goes, my prototype currently uses the Weld SE CDI reference implementation
as the container and I have completed eventing support, JPA injection, and JMX CLI support.
I am close to completing repository import/export leaving compilation, interpretation, and
deployment. If the ODE project team finds any merit in the work I am doing I would be happy
to check the code into a new experimental branch for the project or host it on github.




As always, any feedback is warmly welcomed!



Regards,



Aaron 





 



--- On Wed, 3/23/11, Shivaraj Tenginakai <tshivaraj@gmail.com> wrote:



From: Shivaraj Tenginakai <tshivaraj@gmail.com>

Subject: Re: Evolvable OModel

To: "Gary Brown" <gary@pi4tech.com>

Cc:

 dev@ode.apache.org

Date: Wednesday, March 23, 2011, 8:06 AM



Also, if we can get this done - it would be possible to plug and play

multiple engines. Each engine may be optimized for a different use

case (for example,  Long Running Processes vs. Short Processes).



Thanks,



Shivaraj





On Tue, Mar 22, 2011 at 9:50 PM, Gary Brown <gary@pi4tech.com> wrote:

> Agreed - just need to use a reference that remains stable across

> compilations, but still uniquely identifies the relevant node in the

> DAG.

>

> Regards

> Gary

>

> On Tue, Mar 22, 2011 at 3:43 PM, Shivaraj Tenginakai

> <tshivaraj@gmail.com> wrote:

>> Way I have seen this implemented is that we need to

 distinguish

>> between user state and ode state. ODE state represents the structure

>> of the DAG while the user state represents the value of the variables

>> and the position in the DAG .

>>

>> If we can achieve a clean separation between ODE state and user state,

>> then future evolution would become easy.

>>

>> Shivaraj

>>

>>

>> On Tue, Mar 22, 2011 at 8:42 PM, Tammo van Lessen <tvanlessen@gmail.com> wrote:

>>> Hi Shivaraj, hi Gary,

>>>

>>> yes and no: first, when compiling the process model, each OModel node

>>> contains a unique ID and this is currently a GUID. Thus, even if the

>>> BPEL code is unchanged, the OModel nodes will have different IDs after

>>> compilation. Second, these IDs

 are used when serializing the runtime

>>> state. The JACOB soup keeps references to the OModel. When serializing

>>> the state, these references are replaced by placeholder objects that

>>> store the GUID of the original node to avoid serializing the whole

>>> OModel object graph. This is an optimization to save time and space.

>>>

>>> Tammo

>>>

>>> On 22.03.2011 15:35, Gary Brown wrote:

>>>> Hi Shivaraj

>>>>

>>>> As far as I am aware this issue is not related to state - only the

>>>> static representation of the business process. The OModel simply

>>>> represents a binary compiled version of the BPEL process definition.

>>>> So all I am suggesting is rather than store the binary version, we

>>>> store the xml version, compile on first load, and the end

 result is an

>>>> up-to-date OModel, regardless of the age of the process instance.

>>>>

>>>> Regards

>>>> Gary

>>>>

>>>> On Tue, Mar 22, 2011 at 12:34 PM, Shivaraj Tenginakai

>>>> <tshivaraj@gmail.com> wrote:

>>>>> Gary,

>>>>>

>>>>> Would it be possible to distinguish between execution optimization and

>>>>> state? As long as state information can be derived from one version to

>>>>> another, it should be fine to recompile (to achieve execution

>>>>> optimization).

>>>>>

>>>>> Thanks,

>>>>>

>>>>> Shivaraj

>>>>>

>>>>>

>>>>> On

 Tue, Mar 22, 2011 at 3:40 PM, Gary Brown <gary@pi4tech.com> wrote:

>>>>>> As discussed on the call today, we need a way to overcome the

>>>>>> constraints of the serialized OModel which is produced when compiling

>>>>>> the BPEL process.

>>>>>>

>>>>>> Although a more flexible serialization mechanism may provide a

>>>>>> solution, as was also discussed, there will be cases where additional

>>>>>> logic would be required to determine how an older representation

>>>>>> should be evolved into a new representation.

>>>>>>

>>>>>> Another approach would be to use the BPEL process (xml) directly,
so

>>>>>> rather than using a binary representation

 compiled in advance, the

>>>>>> runtime would simply load the BPEL DOM.

>>>>>>

>>>>>> If this required a change to the internal OModel mechanism, then
it

>>>>>> may be more work than the proposed dynamic OModel idea, however if
we

>>>>>> simply took the approach of "compile on load", then we get away from

>>>>>> the issue, which is the persisted serialized form. We also no longer

>>>>>> require any specific migration logic to move from older versions
of

>>>>>> the persisted representation (dynamic or not).

>>>>>>

>>>>>> So we could keep the existing OModel format, which can evolve as

>>>>>> required as long as the compiler is kept in step, and we should no

>>>>>> longer have any issues with long running

 processes.

>>>>>>

>>>>>> This change could be introduced into the current 1.3.x trunk without

>>>>>> any backward compatibility issues.

>>>>>>

>>>>>> The only trade off is the speed difference between (1) loading the

>>>>>> compiled representation versus (2) parsing the XML & compiling
the

>>>>>> BPEL process. If this would need to be performed multiple times in
the

>>>>>> same runtime, then a hash of the process could be used to cache the

>>>>>> compiled version so this is only performed once per process

>>>>>> definition.

>>>>>>

>>>>>> Thoughts?

>>>>>>

>>>>>> Regards

>>>>>>

 Gary

>>>>>>

>>>>>

>>>

>>> --

>>> Tammo van Lessen - http://www.taval.de

>>>

>>

>




-- 
Cheers, 
Jeff Yu

----------------
blog: http://jeff.familyyu.net




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