[jboss-dev] Remoting 3.0

[Tim Fox]

Ron Sigal wrote:
>
>
> Scott M Stark wrote:
>> The main problem for me with the TowardsGreaterSymmetryInRemoting page
>> is that its not talking about a base asynch message oriented
>> architecture. Much of the current asymmetry's is due to the rpc oriented
>> api. If you flip this around to have a base asynch message view, all
>> communication is handling of these messages. RPC with callbacks is
>> setting up blocking message handlers. Symmetry from a higher level
>> Client api is also not a requirement in my view. By definition a
>> callback is an unpredictable event/out of band msg with respect to some
>> rpc call returning a value. The use of client and server are also by
>> definition asymmetric and map to msg senders/receivers. We need to start
>> from the bottom and move back up to the rpc api in order to be able to
>> talk about what the 3.0 version of Client should look like. 
>>   
>
> Actually, a "base asynch message oriented architecture" was just what 
> I was trying to get at.  While Remoting should continue to support the 
> rpc model, the Connection.receive() and Connection.send() methods that 
> I mentioned are intended to support asynchronous message sending and 
> receiving.
Does Connection.receive() block until it receives a message()?

Remoting 3.0 needs to support non-blocking semantics too to cope with 
very large numbers of connection (We can't have a thread per connection 
blocking on receive()).

What you probably need is some kind of select() functionality (see the 
Java NIO API or unix select() and poll()) where you can register for 
events - in this case a single (or small group of) thread(s) would 
register for events on multiple "channels" and are woken up when an 
evens matches the selector.

You probably also want to build in support for aynchronous IO via 
callbacks - in this case, you don't even have thread(s) waiting on 
select() but register some kind of callback handler and the OS calls 
your handler directly - this can occur with less context switching than 
select().

> Also, while it's true that client and server roles are inherently 
> asymmetric, actors can play multiple roles (like Peter Sellers).  In 
> Remoting, for example, callbacks (in push mode) are handled by clients 
> on the server side talking to servers on the client side.  I think the 
> same thing would be conceptually simpler with a "connection" 
> abstraction that mirrors a real TCP connection: it's true that there 
> are client and server sockets, but once the connection has been 
> created, there can be senders and receivers on both sides.
>
>> The architecture also needs to be layered such that you can plug into
>> low level message creation for the case of needing to control the on the
>> wire format of these messages.
>>
>> We are brining on the MINA lead, Trustin Lee, so we will need to look at
>> how
>>
>>   
>
> The idea of stacks of marshallers and unmarshallers in Remoting has 
> been floating around for a while, and Tom did some initial work in 
> that direction.  I'm thinking that's where the layered message 
> handling will live.  I've been meaning to write a second document on 
> the subject, but, in fact, MINA has a pretty flexible and 
> sophisticated framework for chains of message handlers, which looks 
> like a good match for what we want.  As you say, we need to understand 
> how MINA and Remoting will work together.
>
>> Anil Saldhana wrote:
>>   
>>> Ron,
>>>  Most of it may already be present.
>>>
>>> Here is what I am thinking:
>>> a) Pluggable mechanism to do authentication at either ends of the pipes
>>> (SASL)
>>> b) Pluggable ways to secure the payload that passes through the pipes.
>>>
>>> Regards,
>>> Anil
>>>
>>> Ron Sigal wrote:
>>>     
>>>> There have been various attempts to get some discussion going about
>>>> the features desired for the next generation of Remoting, and so far I
>>>> think the buzz has broken the -80 db level.  I'm trying again with the
>>>> wiki page at
>>>> http://wiki.jboss.org/wiki/Wiki.jsp?page=TowardsGreaterSymmetryInRemoting. 
>>>> We in the Remoting group (i.e., me in the Remoting group) would like
>>>> to hear from the Remoting stakeholders about what features would make
>>>> Remoting more usable for you.  Of course, I could just go ahead and
>>>> write fun stuff.  :-)
>>>>
>>>> -Ron
>>>>       
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>>
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