Hi Roland
Our focus is on a comfortable blocking
API, since that is what most users want and also what we
need in order to obsolete the 3.x version of HttpClient.
However, if Synapse has good ideas about a comfortable
non-blocking API which we could put on top of HttpCore,
please let us know.
A non-blocking client API is important to Synapse, as we may act as a
client to many back-end servers, on behalf of our [actual] clients.
Since we run on top of Apache Axis2, it is a requirement to allow
reading from and writing into streams. For example, if we are reading a
huge Base 64 encoded message and sending it to another server as an MTOM
optimized SOAP message, we want to support this without reading the
whole message into our memory or waiting for the whole message to be
received from the client before we start sending it out. However, I
understand that in such scenarios, the application threads may block if
an internal read buffer runs dry waiting for data.
This brings up another question, .. If I use HttpCore-NIO, and start
reading a SOAP message and as soon as I am done reading my SOAP header,
I start to process it, it is possible that your internal read buffer
gets filled up during this time. Once the read buffers are full, do you
reject available reads so that you could retry to read them in the
buffers again in your next select cycles? I am assuming that you do...
Synapse also wants SSL support in server and client mode, and we are ok
to move to JDK 1.5 to do this with NIO.
Another optimization we would like to have is the ability for the client
API to be able to reuse underlying connections if possible - i.e.
something in the lines of a connection pool. In some preliminary
performance testing, opening a new socket for each message being sent to
a back-end causes us a huge cost.
I don't know MINA myself, but Oleg does and he has taken
care that HttpCore-NIO should be easy to run on top of
MINA.
Could you explain this in a bit more detail? i.e. if we run HttpCore-NIO
on top of MINA I assume all calls made on the HttpCore-NIO APIs will
never block as MINA has already buffered the complete messages.. ?
That's why I recommend that you don't develop a
new HTTP framework. Even if it might seem that you save
some effort now by implementing a "good enough" solution,
you will eventually run into the same kind of problems
that we have seen with HttpClient over the years.
I see this point much more clearly than sometime back..
I am going to take the next couple of days to dive again into HttpCore,
Client and the NIO extensions in more detail, and would try to create a
basic transport for Synapse using them. We are planning to make a
decision on this in the next two weeks as we are getting ready for our
1.0 soon after this is ready.
thanks
asankha
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