Matteo Campanella wrote:
Hello, I have found an old post about how to modify squid to cache POST
responses (copied below) and I would like to know a couple things.
The post you found is a mix of someones earlier request identical to
yours. And Henriks expert reply covers exactly what need to be done.
Nothing has changed since then.
I was thinking to implement POST caching by letting the POSTed body to
contribute to the construction of the MD5 key in
storeKeyPublicByRequestMethod function, simply by adding one more call to
SQUID_MD5Update using the body as parameter - is it the right place where to
calculate the store key?
To thing you need to think about a bit more...
The use-cases that need to be considered when moving request bodies include:
* MB of data in POSTs is quite common
* 'infinite' length are even more common.
* requests lasting several hours or days are also known.
Handling all of the above in a pre-calculated MD5 is not nice. Thus the
buffering requirement.
The question of really: does the POST need to actually reach the web server?
- YES: then it cannot be cached.
- NO: then why is a POST being used at all?
RFC 2616 permits the use of a GET request with body data (must not
affect the reply) plus the same dynamic URL and/or headers sent in the POST.
In order to do what reported above, I need the body bytes to be available
inside the storeKeyPublicByRequestMethod function; how can I do that? I've
read the httpSendRequestEntry() function but honestly it did not make things
clearer :)
Looking foward for your response, I wish you merry xmas and happy new year!
ciao
Matteo
[attributions corrected below]
-------------------------------->
Subject: Re: Where to deal with POST? Actions From: Henrik
Nordstrom
([email protected]) Date: Nov 6, 2003 12:41:48 am List: org.squid-
cache.squid-dev
On Thu, 6 Nov 2003, Zhou Hong wrote:
I am now working on to add function module of caching web services to squid
2.5.
Since the soap requests of web service use POST and squid marks the POST
request nocache, I have to find where to modify the manipulation of POST
Henrik wrote:
Squid does not cache POST replies as it is uncertain under which conditions
a POST reply may be cached. Most uses of POST depends heavily on the
contents of the POST request entity.
If your goal is to make POST cacheable then there is a couple of things you
need to do, assuming this caching is dependent on the POST request data:
* Modify how request entities are forwarded, temporarily buffering the
entity so you can process the request entity before the request is
forwarded.
* Extend the public storeKey hashed data with information as required to
give each POST request/reply which should be cached uniquely a unique store
key.
* Remove the flag which makes POST requests uncacheable (look for
METHOD_POST).
I also encounter the following question when looking into codes, and need
your help,
Zhou Hong wrote:
1) Where to get POST request content body?
Henrik wrote:
See httpSendRequestEntry() for an example.
Zhou Hong wrote:
2) Besides url, which other things are selected to form the hash key.
Henrik wrote:
See storeKeyPublicByRequest()
Zhou Hong wrote:
3) What is the difference between storeSetPrivateKey and storeSetPublicKey,
I mean What scenarios do we use private key and public key respective in.
Henrik wrote:
Every object in Squid must have a unqiye key identifying the object to
Squid.
Objects which should not be shared with other clients use private keys,
shareable objects use public keys.
All objects start out private and when Squid determines the response may be
cached the key is changed to the public key.
Amos
--
Please be using
Current Stable Squid 2.7.STABLE7 or 3.0.STABLE21
Current Beta Squid 3.1.0.15
