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From Andreas Veithen <>
Subject Re: [GSoC Project Proposal] Distributed TCP Monitor
Date Tue, 30 Mar 2010 08:57:14 GMT
I was actually referring to scenarios where a service may call other
services, which in turn may call again other services. In these
scenarios, it is not sufficient to simply collect received/sent
messages on different hosts, unless the system is isolated
(development environment) or the request rate is sufficiently low so
that messages can be correlated based on time. Here is a concrete
scenario from a project in my company:

- Request comes in on an ESB that does security and validation.
- Request is processed by an application server which persists the
received information and publishes a JMS message (pub/sub events).
- The event is consumed by one or more components that may in turn
interact with other services.

If you want track this flow, it is not sufficient to intercept the
messages on the different hosts: in addition, you need to instrument
the services so that the outgoing requests are correlated with the
incoming requests (by adding SOAP and/or transport headers). What I
would like to be able to do in the above scenario is to enable
end-to-end monitoring on a per-message basis: I add a special SOAP or
HTTP header to the initial request to enable logging and this
information is propagated along the chain. Every service/component
then sends a copy of the incoming/outgoing requests/responses to a
central place where the sequence of events is reconstructed.

One way this could be achieved is with a tool that postprocesses the
artifacts from the build process. For each artifact, the tool would
disassemble the artifact, instrument the code using a set of AspectJ
aspects and reassemble the artifact for deployment. The responsibility
of the aspects would be to intercept messages, log them and modify
them to ensure proper correlation. Of course this only works if the
artifacts are J2EE deployables (WARs or EARs). Note that we already
use AspectJ for a similar use case (although at a much smaller scale)
in the transport test suites [1]. Interestingly, this approach would
allow to cover interactions that are not SOAP based, e.g. one could
even intercept the database queries executed during the flow.



On Tue, Mar 30, 2010 at 09:11, Srinath Perera <> wrote:
> Hi Nilupa;
> When we collect messages from a one location by installing proper
> handler that will intercept and send messages to to that one location
> (this one location can be a single server, pub/sub channel etc). There
> is many ways to make sense of those collected messages. What Andreas
> mentioned (following complete transaction) is a one possibility.
> I think you should come up with few scenarios on how you would make
> sense of the message.
> Thanks
> Srinath
> On Sun, Mar 28, 2010 at 9:46 PM, nilupa bandara <> wrote:
>> Hi,
>> First let me thank you for commenting.
>> As far as I understood, what you would like to see from the proposed
>> tool is to view set of messages that are exchanged in reponse to a
>> particular input message. With the understanding that I am having at
>> the momnet, one way to do it is to filter out the central repository
>> of messages based on 'To' , 'From' headers and try to contruct the
>> message chain from it. We can allow the client GUI wich connects to
>> the central repository to provide the paramenters (For instance the
>> value of 'To' header) from which an intelligent filtering can be done
>> for the set of messages avialable at the central repository.
>> Perhaps someone has an idea of a better way of doing it and is willing
>> to share it with us. It would be really nice to hear from them.
>> Thanks in advance ..!!
>> Best Regards,
>> Nilupa
>> On Sat, Mar 27, 2010 at 6:40 PM, Andreas Veithen
>> <> wrote:
>>> Personally, I think that the added value of extending the SOAP monitor
>>> module to collect messages in a central place is too limited to
>>> attract enough interest from the user community, so that it will be
>>> difficult to ensure the evolution of such a project in the future.
>>> However, what many people are looking for is a tool that allows to
>>> track the flow of a message through a distributed system, or more
>>> generally to track the sequence of events triggered by a given input
>>> message (sort of end-to-end transaction monitoring).
>>> On Wed, Mar 24, 2010 at 23:03, nilupa bandara <> wrote:
>>>> Hello,
>>>> I am graduate student at Politecnica de Madrid and I am thinking of
>>>> proposing a GSoC project this summer. I would like to take project
>>>> "Distribute TCP Monitor" descried[1] which is very interesting and
>>>> also should be helpful to any Java developer using Apache Axis2 Web
>>>> services middleware. I will submit more detailed proposal later. I
>>>> would really like to hear any feedback from you. Any suggestions or
>>>> features that you would like to see in a "Distributed TCP Monitor" are
>>>> most welcome.
>>>> Best Regards,
>>>> Nilupa Bandara
>>>> [1]
>>>> Distributed TCP monitor
>>>> To use TCP monitor we have to tweak the endpoints, which is bit hard
>>>> sometimes (e.g. two channels Async case for Axis2). We can solve the
>>>> problem by writing a Axis2 module (Handler) that intercept messages
>>>> comes in and goes out of a Axis2 server and send to a UI (via a
>>>> pub/sub channel or a message Box e.g. ) or record them so user can
>>>> pull those messages. Also, we can do something to turn the module on
>>>> and off remotely, so users can have his module deployed, but turn it
>>>> on only when they want to debug the system.
>>>> Then we can take this to next level by adding this module to all
>>>> services in a system , configuring modules to send all collected
>>>> messages to a pub/sub channel, and subscribing to those messages via a
>>>> UI, and depicting those messages through a UI. Then users have a
>>>> TCPMon for a whole system.
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> --
> ============================
> Srinath Perera, Ph.D.
>   WSO2 Inc.
>   Blog:
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