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[nycphp-talk] AJAX and State

Elliotte Harold elharo at metalab.unc.edu
Fri Sep 7 07:35:41 EDT 2007


David Krings wrote:
>
> But isn't that the old GET that has so many limitations that many web 
> app design guides basically tell you not to use it?

I have no idea what you're talking about. GET is GET. There's no old GET 
and new GET that I've ever heard of.

It's certainly true that there are a lot of bad web app design guides 
out there. Most of them try to reinvent client server on the web. 
They're like a manual for plastic molding machines that pretends the 
molder is really just a funny kind of table saw and drill press. Follow 
their directions and you'll develop problematic, unscalable 
applications; and certainly lots of people do.

> And it depends on what you transfer in clear text as URL parameters. A 
> Google search is probably OK, but what if your application is about 
> sensitive data? You then need to craft identifiers that are dropped 
> after first use and never used again or some other untraceable 
> obfuscating mechanism.

No. You use HTTPS.

> There was also the point made of scalability. As in this example, the 
> search results are not stored anywhere, but get recreated each time a 
> request is sent. That pushes the scalability issue from the web server 
> to the database server, where it may or may not be handled more 
> efficiently.

In point of fact, Google uses probably millions (maybe hundreds of 
thousands but I expect millions) of servers. They need this massive 
horizontal scalability. To make that work you really need to not care 
which server processes any given request. Three subsequent requests can 
and usually do go to three different physical servers. The more session 
state you try to maintain the harder that is to handle.

By contrast, if you design apps so they don't need session state, then 
you can scale horizontally very easily and you need a lot fewer actual 
servers.


-- 
Elliotte Rusty Harold  elharo at metalab.unc.edu
Java I/O 2nd Edition Just Published!
http://www.cafeaulait.org/books/javaio2/
http://www.amazon.com/exec/obidos/ISBN=0596527500/ref=nosim/cafeaulaitA/



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