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From Owen O'Malley <omal...@apache.org>
Subject Re: HTTP transport?
Date Thu, 08 Oct 2009 22:10:50 GMT
I still don't see how to make this play well with security. Security  
needs to go under the transport layer so that it is easy to add  
encryption on the wire. If you go with HTTP, the only way that is  
portable at all is to use HTTP over SSL. SSL is for when there aren't  
shared keys and Kerberos provides those shared keys. SPNEGO is the  
standard method of using Kerberos with HTTP and we are planning to use  
that for the web UI's. But SPNEGO is very much the least painful of  
the alternatives and I'd rather not force our RPC services into that  
corner.

I also have serious doubts about performance, but that is hard to  
answer until we have code to test. It is an interesting question how  
much we depend on being able to answer queries out of order. There are  
some parts of the code where overlapping requests from the same client  
matter. In particular, the terasort scheduler uses threads to access  
the namenode. That would stop providing any pipelining, which I  
believe would be significant.

In short, I think that an HTTP transport is great for playing with,  
but I don't think you can assume it will work as the primary transport.

-- Owen


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