(Dis)Proving that 303s have a performance impact.

On 16 Feb 2013, at 19:26, Kingsley Idehen <kidehen@openlinksw.com> wrote:
> On 2/16/13 1:11 PM, Henry Story wrote:
>> On 16 Feb 2013, at 18:37, Kingsley Idehen <kidehen@openlinksw.com> wrote:
>>> Yes, its got to be so simple that it won't take you time to make the entire experiment, and then present a set of conclusions drawn from your observations etc..
>> What is the experminent we need to do? Can you describe it?
> 
> I don't have time for games. You outlined a set of claims upon which you've arrived at disputed conclusions. Thus, you already know the description of your experiment since you are the very same person that's provided its hypothesis.

Ok, so we need to compare like with like, in order to be able to have an expermiment.
So we put ourselves in a user's shoes. He has to choose between either hash WebID, 
or a 303 WebID . He has the same information to publish in both cases 

Hash:          http://joe.example/hash/joe#me
Non Hash:      http://joe.example/resource/joe

So we have the WebID and we need to get the WebID Profile document [1].
Let us say the Profile document is of size S . 

A. Hash URL
-----------

A.1 Client does an HTTP GET on 
   http://joe.example/hash/joe
 
A.2 Client receives document of size S


B. Non Hash URL
---------------

B.1 Client does an HTTP GET on 
   http://joe.example/resource/joe

B.2 Client received a 303 redirect to 
   http://joe.example/document/joe

B.3 Client does an HTTP GET on  
    http://joe.example/document/joe

B.4 Client received content of size S


Conclusion
-----------

Given that the size of the documents are the same in both cases, and that we
work with the same network speeds in order to remove accidental varations of speed,
We see that B requires 1 more HTTP request to the server that A does.

Therefore the difference in speed between A and B is exactly the difference of 
a message exchange. This difference will always exist no matter what the network
setup.

The noticeability of this will vary depending on the distance of the client to the
server, and the size of the document. But it will always exist. There is therfore
an efficiency gain to be had by choosing the hash url for free.

Q.E.D.

Henry

[1] https://dvcs.w3.org/hg/WebID/raw-file/tip/spec/identity-respec.html
[2] ISSUE-74

Social Web Architect
http://bblfish.net/