What is the size limit of a post request?

Question

Sorry if this is duplicate,I would think it would be but couldn't find anything.

I have a flex application that I am posting data back to a php/mysql server via IE. I haven't run into any problems yet, but knowing this ahead of time might save me a bunch of frustration and work. Is there a size limit to posting data via http?

This article says no: http://www.netlobo.com/ie_form_submit.html

This discussion says yes: http://bytes.com/topic/php/answers/538226-what-maximum-limit-using-post-method

And it all goes back and forth what I'm able to find online. So please limit answers to personally tested/verified numbers.

I am wanting to post back an XML string that can be quite large (say up to 5mb).

If it makes any difference: browser will always be IE (our product requires it), post is coming from and httpService in flex, web server is php, DB is mySql.

Answer 1

It's a server configuration. If you're working with PHP under Linux or similiar, you can control these using .htaccess, like so:

#set max post size
php_value post_max_size 20M

And, yes, I can personally attest to the fact that this works :)

If you're using IIS, I don't have any idea how you'd set this particular value.

Answer 2

It is up to the http server to decide if there is a limit. The product I work on allows the admin to configure the limit.

Answer 3

The url portion of a request (GET and POST) can be limited by both the browser and the server - generally the safe size is 2KB as there are almost no browsers or servers that use a smaller limit.

The body of a request (POST) is normally* limited by the server on a byte size basis in order to prevent a type of DoS attack (note that this means character escaping can increase the byte size of the body). The most common server setting is 10MB, though all popular servers allow this to be increased or decreased via a setting file or panel.

*Some exceptions exist with older cell phone or other small device browsers - in those cases it is more a function of heap space reserved for this purpose on the device then anything else.