Hi All,
Before differing this task, I implement a quick POC and manage to get this
to work for the sequence flows which does not contain list mediators like
Filter, Switch etc.
Flow
------
Proxy
InSequence
Log - IN SEQ P1
Sequence Mediator ----> Sequence 1
Log - IN SEQ P2 Log - SEQ1 P1
Sequence
Mediator ----> Sequence 2
Log - SEQ1 P2
Log - SEQ2 P1
Send
Send
Log - SEQ1 P3
Log - SEQ2 P2
Output on the console
-------------------------------
[2013-08-09 20:20:12,283] INFO - LogMediator MSG = IN SEQ P1
[2013-08-09 20:20:12,285] INFO - LogMediator MSG = SEQ1 P1
[2013-08-09 20:20:12,286] INFO - LogMediator MSG = SEQ2 P1
[2013-08-09 20:20:12,303] INFO - LogMediator MSG = SEQ2 P2
[2013-08-09 20:20:12,304] INFO - LogMediator MSG = SEQ1 P2
[2013-08-09 20:20:12,320] INFO - LogMediator MSG = SEQ1 P3
[2013-08-09 20:20:12,321] INFO - LogMediator MSG = IN SEQ P2
Rather than implementing a new mediator, I introduced a new parameter for
the send mediator called "continuation".
<send continuation="true"/>
After setting the continuation to true, mediation is continued from the
next mediator placed after the send mediator with the received response.
When flow is completed in a particular sequence, mediation will be
continued from the parent sequence. Behavior is identical to the Callout
mediator.
Over the weekend, I put some effort to see whether I can extend this to
support sequence flows which contains other list mediators like Filter,
Switch, etc and managed to get it to work.
And managed to get this to work for Templates as well.
Design in brief
---------------------
- To keep track of sequence branching, a stack (called 'Sequence Calls
Stack') is kept in the message context which is similar to the fault stack.
- Every time when we branch to a new sequence, a entry (called
'SequenceCall') is pushed in to the stack.
- A SequenceCall contains the sequence name and the position of the
mediator in the sequence.
- When branching to a new sequence, top is updated with the current
mediator position.
- When message is sent out from the send mediator, top is updated with
the current mediator position and a property is added to the message
context to indicate continuation=true. And flow will be stopped from there.
- When response is received, while injecting the response at the
Axis2SynapseEnvironment, it checks for the continuation property from the
message context. If it is present, it will peek the stack and using the
information contain in that peeked SequenceCall, mediation will be
continued from where it stopped earlier.
Above is a very high level description of the design I came up with. Actual
design which I implemented to support other list mediators and templates is
bit more complex than this.
Today I had a peer review with Kasun on this implementation.
Source of the current implementation is located at [1] and tested artifacts
are located at [2].
[1]
https://svn.wso2.org/repos/wso2/people/isuruu/non-blocking-callout-impl/2.1.1-wso2v8
[2]
https://svn.wso2.org/repos/wso2/people/isuruu/non-blocking-callout-impl/test-artifacts
Thanks,
IsuruU
On Mon, Aug 12, 2013 at 10:42 PM, Sanjiva Weerawarana <[email protected]>wrote:
> As discussed .. this is not a real need so we'll defer.
>
>
> On Thu, Aug 8, 2013 at 3:07 PM, Kasun Indrasiri <[email protected]> wrote:
>
>> We have been discussing the $subject for sometime and I guess now we
>> have a real requirement for this with connectors. Since most connectors
>> uses callout mediator for external calls, we will surely experience
>> perf-issues when the connectors are used in real world scenarios.
>>
>> So, we should make callout work with non-blocking transports. This is not
>> a trivial thing to implement as we have to implement a blocking scenario on
>> top of a non-blocking transport, but it should be possible to do something
>> along the lines of receiving seq impl we have at the moment.
>>
>> Isuru is currently looking for a possible design to implement this.
>>
>> --
>> Kasun Indrasiri
>> Software Architect
>> WSO2, Inc.; http://wso2.com
>> lean.enterprise.middleware
>>
>> cell: +94 71 536 4128
>> Blog : http://kasunpanorama.blogspot.com/
>>
>
>
>
> --
> Sanjiva Weerawarana, Ph.D.
> Founder, Chairman & CEO; WSO2, Inc.; http://wso2.com/
> email: [email protected]; phone: +94 11 763 9614; cell: +94 77 787 6880 | +1
> 650 265 8311
> blog: http://sanjiva.weerawarana.org/
>
> Lean . Enterprise . Middleware
>
--
*Isuru Udana*
*
*
Senior *
Software Engineer
*
WSO2 Inc.; http://wso2.com
email: [email protected] cell: +94 77 3791887
blog: http://mytecheye.blogspot.com/
twitter: http://twitter.com/isudana
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