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From Connor Doyle <connor....@gmail.com>
Subject Re: Avro RPC
Date Wed, 29 May 2013 18:36:31 GMT
In the parlance of the relevant section of the Avro specification ("Protocol Wire Format"),
I'm talking about a stateful connection.  The agreed-upon client and server protocol versions
are part of the connection state, as are the pending requests at each client.  By tagging
each request with a sequence number we can allow responses to roll in asynchronously.  We
encode this identifier as an Avro long in the metadata map sent with each message, as laid
out in the spec for the call format.  In our case, we're using a web socket connection as
the transport layer.

On May 29, 2013, at 12:50, Mark <static.void.dev@gmail.com> wrote:

> Didn't know Avro RPC could maintain a persistent connection. Would you mind elaborating
on your use case?
> On May 29, 2013, at 10:08 AM, Connor Doyle <connor.p.d@gmail.com> wrote:
>> Avro RPC can be _dramatically_ more compact, especially when used over a persistent
connection.  We use binary avro RPC over a WebSocket connection.  The overhead for each request
is a tiny blob of metadata and the message name.  This compares very favorably with a full
set of HTTP headers for each message.  Another advantage we see is that with a persistent
connection we can handle responses asynchronously; quickly serviced requests don't have to
wait for slow ones.  It all depends on the details of your use case, however.
>> --
>> Connor
>> On May 29, 2013, at 11:30, Mark <static.void.dev@gmail.com> wrote:
>>> Very basic question but could one explain why one would choose Avro RPC over
something like a simple restful service over HTTP? 
>>> The only thing I can think of is it adds a little more structure to the request/response
and slightly more compact. Other than that, I'm drawing a blank. As far as the response goes
though, couldn't you simply return an Avro message from a restful http service and have the
client parse it if you wanted more structure?
>>> Thanks for the clarification
>>> -M

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