Re: [squid-users] Generell Squid setup

On 7/09/2012 9:39 a.m., Farkas H wrote:
> Hi Amos,
>
> thanks for your response.
> I modified the web application. Now we have the following infrastructure.
> client --> http-Post [embedded http-Get] --> Server / web application
> --> http-Get --> Squid -> Servers (-> Squid -> Server / web
> application -> client)
> Advantage: The Server / web application doesn't have to request data
> from the remote servers if it's in the Squid cache.
>
> Additionally I want to cache the http-Post requests.
> client --> http-Post --> Squid --> Server / web apllication /
> processing the response (-> Squid -> client)

Requests body is not cacheable in HTTP.

The body content is the state to be changed at end-server resource in
the URL. Caching it is meaningless, since next time the state needs to
be changed you CANNOT simply reply from a middleware cache saying
"server state now changed" without passing any of those details to the
server.

Additionally, your translation service is re-writing the POST into GET
requests so the POST ceases to exist at your gateway service. There is
nothing to cache.

>
> The idea: We modify the header of the http-post request to make it unique.
> The information whether Squid has a stored response to the modified
> request (true or false) should be added to the request / should be
> forwarded to the destination server. There are two possibilities.
> (1) The modified request is not stored in Squid (new request).
> (2) The modified request is stored in Squid. We don't know yet if the
> data is still fresh.
> The request should be forwarded in both(!) possibilities, (1) and (2),
> to the destination server.
> Is that possible with Squid?

Of course. That is dependent on the Cache-Control: headers the server
supplies to Squid with its responses and applies to each response
independent of anythign else.

Send "Cache-Control: must-revalidate" and Squid will query the server
for each request asking if there are updates.

Amos
Received on Sat Sep 08 2012 - 02:48:36 MDT