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From Danny Sullivan <dsulliv...@hotmail.com>
Subject RE: [DISCUSS] Switching Streams from Camel deployment to .war deployment
Date Wed, 30 Oct 2013 18:38:57 GMT
Thanks for the feedback. You have an interesting point about the url linking to a separate
processing space. Let me tie my answer into your last question about "advocating for the simplicity
at registration to give up flexibility at registration, but retaining the inner "guts" of
EIP/messaging". Consider a new architecture:

streams-web.war: single entry point to application, but functions ONLY as an entry point.
From here Camel routes the incoming requests to 4 separate jarssubscriber-registration.jar:
subscriber registration publisher-registration.jar: publisher registrationactivity.jar: returns
activity (also contains subscriber warehouse and storm activity aggregator)publish.jar: publishes
activitystreams-cassandra.jar: the above 4 jars would all have a hook into this jar which
would function as a hook onto the database. Each jar would have camel route output to this
jar.

In this implementation, Camel would no longer be the entry and exit point of a client to the
application, but would handle the communication between components. The flow of activity through
the application would be method based in each jar. This would allow deployment on up to 6
different process spaces. However, this does not address that there is a single server entry
point, but I'm not sure if it was a concern in the first place.

My argument, at its basis, is that we should move away from using Camel as the entry point
to the application. I would be happy to maintain messaging between components.

> Date: Wed, 30 Oct 2013 12:32:55 -0400
> Subject: Re: [DISCUSS] Switching Streams from Camel deployment to .war deployment
> From: jletourneau80@gmail.com
> To: dev@streams.incubator.apache.org
> 
> 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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