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From Jason Letourneau <jletournea...@gmail.com>
Subject Re: [DISCUSS] Switching Streams from Camel deployment to .war deployment
Date Wed, 30 Oct 2013 16:32:55 GMT
An interesting use case that I am holding onto is the ability for
publishers to register via a single URL (registration endpoint), but
be sent a URL back to post to a different process space for actual
publishing.  The same is true on the subscriber front.  Currently, the
Camel/EIP infrastructure abstracts this because different components
deployed in different process spaces handling the route creation can
just be bolted onto a running Streams instance without new subs/pubs
behaving any differently than existing.  This seems to be a
potentially critical scaling point.  Is there a way to do this with
the Spring solution?

The persistence point is a good one, though I would classify that as
"not implemented" vs "not possible" (not that you were).

I'm not married to Camel, I just like the EIP approach to building
something that is ultimately a messaging system.  There are known
patterns that solve at least a subset of the problems Streams is
trying to solve and implementations that can handle the load and I'll
reiterate flexibility == complexity almost always.

It comes right back to the central question: Do you want flexibility
or simplicity?  It doesn't have to be black and white either I don't
think...

More pointedly: Where should we give up flexibility for simplicity?  I
read that Danny is advocating for the simplicity at registration to
give up flexibility at registration, but retaining the inner "guts" of
EIP/messaging?  Thoughts?

On Wed, Oct 30, 2013 at 11:37 AM, Danny Sullivan <dsullivan7@hotmail.com> wrote:
> My argument is not for the IoC pattern as that can be (and has been) implemented alongside
Camel. My main argument is that the syntax at the entry point is not only familiar but much
simpler. This wouldn't be a very strong argument if the Camel implementation wasn't much more
complicated but I feel that it is the case. Also, looking toward the future, if the server
is restarted, in-routes are lost in Camel. The way to curb this is to persist the dynamic
routes that Camel creates, and then on start up pull every one of these routes and recreate
a dynamic route for each one. Not only is this much easier to implement using the Spring web
implementation, but it already has been implemented and you can try it by checking out the
webservice branch, registering a subscriber, restarting tomcat, and using the same url you
had before. This will allow subscribers to hang on to their urls once they register. (the
same is true for publishers: you can post via the same url after restarting tomcat)
>
>> Date: Wed, 30 Oct 2013 11:00:21 -0400
>> Subject: Re: [DISCUSS] Switching Streams from Camel deployment to .war deployment
>> From: jletourneau80@gmail.com
>> To: dev@streams.incubator.apache.org
>>
>> To be fair, while the current implementation is heavily camel-based,
>> all of the interfaces related to Streams functionality are not.  The
>> current model maps to what Matt has outlined in my opinion, though
>> packing names etc. probably don't follow that exact pattern.
>>
>> With regards to the complexity and different components in the
>> registration process, this was a cut at the abstraction based on the
>> assumption that different implementations may be plugged in and in
>> fact may live on different processor space (ie. a polling publisher vs
>> a push publisher may be instantiated on different servers but the
>> registration URL is staticly defined).
>>
>> Is the main argument I am seeing for Spring  the familiarity of its
>> IoC pattern implementation and syntax at the entry point?
>>
>> On Wed, Oct 30, 2013 at 10:53 AM, Danny Sullivan <dsullivan7@hotmail.com> wrote:
>> > Could you clarify whether the same entry points would exist for the camel implementation
of the core (implementing the "process" method/ using a DynammicRouteBuilder) or would the
webservice be the sole entry point to Streams and after it enters would it hand it off to
Camel? And what would be the entry point for the Storm implementation?
>> > -Danny
>> >
>> >> Date: Wed, 30 Oct 2013 10:13:04 -0400
>> >> Subject: Re: [DISCUSS] Switching Streams from Camel deployment to .war deployment
>> >> From: m.ben.franklin@gmail.com
>> >> To: dev@streams.incubator.apache.org
>> >>
>> >> On Tue, Oct 29, 2013 at 2:55 PM, Danny Sullivan <dsullivan7@hotmail.com>wrote:
>> >>
>> >> > My case for switching from OSGi is for simplicity in design. To follow
the
>> >> > path of an activity through Streams in the webservice, there is one
main
>> >> > things the developer needs to understand:
>> >> > The @RequestMapping annotation specifies the HTTP entry point
>> >> > There are 4 @RequestMapping annotations that correspond to each of
the 4
>> >> > ways a user enters the application: registering a publisher, registering
a
>> >> > subscriber, publishing activity, and getting an activity stream. Where
>> >> > these are located in the source code can be found by searching for
the
>> >> > paths specified in the documentation (search for "/publisherRegister",
>> >> > "/subscriberRegister", "/publishActivity", "/getActivity" which will
all
>> >> > lead you to StreamsWebController.java). From the methods that process
>> >> > requests, the flow through the application is through methods which
can be
>> >> > understood by most Java programmers.
>> >> > The flow of activities through the current trunk branch is understood
as
>> >> > follows:
>> >> > The string "/publisher/register" (the entry point to register a publisher
>> >> > specified in the documentation) is the value of the
>> >> > consumer.registrationEndpoint property defined in streams.propertiesThe
>> >> > camelContext.xml specifies an endpoint with the id
>> >> > consumerRegistrationEndpoint to have a uri equal to the propertyThe
>> >> > consumerRegistrationEndpoint routes from uri direct:publisher register
with
>> >> > the bean activityRegistrationProcessor nested in between the routeThe
>> >> > streams-eip-applicationContext contains a bean with the id
>> >> > activityRegistrationProcessor created for the class
>> >> > ActivityPublisherRegistrationProcessorThe exchange will enter the "process"
>> >> > method of the class ActivityPublisherRegisitrationProcessor and that
this
>> >> > is because this class implements the "Processor" interface provided
by
>> >> > CamelThe direct:add-publisher-route takes the exchange output from
the
>> >> > "process" method and routes it to the activityRegistrationProcessor
>> >> > "register" method. The bean activityRegistrationProcessor is defined
in the
>> >> > streams-eip-osgi-component-import.xmlThe output from this method is
then
>> >> > sent to the "createNewRouteForConsumer" method of activityConsumerRouter.
>> >> > This method creates a new route for the newly registered publisher
using
>> >> > the private static final class DynamicConsumerRouteBuilder which is
>> >> > required to extend RouteBuilder which is provided by Camel. This
>> >> > DynamicConsumerRouteBuilder contains several methods:
>> >> > getConsumerReceiveMethod() (which corresponds to @Value
>> >> > ${consumer.receiveMethod} which corresponds to "receive"),
>> >> > getConsumerSplitMethod() (@Value ${consumer.splitMethod},"split"),
and
>> >> > getConsumerActivityQUri() (@Value ${consumerActivityQUri},
>> >> > "direct:activityQ"). This is different than the camelContext.xml in
that
>> >> > the route is being created programmatically. What this is doing is
routing
>> >> > input from the inroute url (which Camel does automatically through
the
>> >> > configure method which is required to be overridden), to the "receive"
>> >> > method of ActivityConsumer, then to the "split" method of ActivityConsumer,
>> >> > and then to the "direct:activityQ" which if you look back in the
>> >> > camelContext.xml routes to the "activemq:queue:activities" which then
>> >> > routes to "receiveExchange"
>> >> > This is the process to register a publisher. The process for registering
a
>> >> > subscriber is relatively the same though it involves separate classes
with
>> >> > their own private static final RouteBuilder class. From my perspective,
the
>> >> > two most difficult things with setting this project up were understanding
>> >> > that the "process" method of the class that implements "Processor"
is the
>> >> > entry point and the DynamicConsumerRouteBuilder creates the second
entry
>> >> > point (The 5th and last points). This made the project very, VERY hard
to
>> >> > understand.
>> >> > In addition to simplicity of design, the mvn clean install of the web
>> >> > service project is much faster and small scale activity publishing
is also
>> >> > faster (see my email about load testing). These are minor points though
as
>> >> > compilation has no effect on deployment. OSGi does add the benefit
of
>> >> > modularized programming which is valuable, though I think the added
>> >> > complexity of Camel merits moving the project away from this paradigm.
>> >> >
>> >>
>> >> I agree that the project is pretty difficult to understand ATM.  I think
>> >> what we need to do is think about what the responsibilities of the code
are
>> >> and allow for different implementations that are not so tightly coupled
as
>> >> they are now.  For instance, having worked with Storm to ingest millions
of
>> >> activities a day, I personally would like to see streams be responsible
for
>> >> defining an over-arching orchestration model that can be implemented within
>> >> a single war or on top of a distributed system.  This would look something
>> >> like the follows:
>> >>
>> >> |__ Streams-Core  (Base classes, interfaces, utilities, extensions, etc)
>> >> |
>> >> |__ Streams-Storm (Storm implementation of the core)
>> >> |
>> >> |__ Streams-Camel (Camel implementation of the core)
>> >> |
>> >> |__ Streams-WS (Web service implementation)
>> >>
>> >>
>> >> > Danny
>> >> >
>> >> >
>> >> > > From: dsullivan7@hotmail.com
>> >> > > To: dev@streams.incubator.apache.org
>> >> > > Subject: [DISCUSS] Switching Streams from Camel deployment to
.war
>> >> > deployment
>> >> > > Date: Tue, 29 Oct 2013 11:07:39 -0400
>> >> > >
>> >> > > The discussion thread for switching Streams from Camel/osgi/Servicemix
>> >> > to a single .war deployment
>> >> >
>> >> >
>> >
>

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