Hi Amos, thank you for your response. I think I didn't explain the problem correctly. Let me mention that the http-Post request contains - one or two URLs, - name and parameters of one mathematical function from a set of server functions, - mime-type of the response. The client sends a http-Post request to the server The server ... (1) fetches the data (xml, up to 100 MB) via http-Get using the reference which is embedded in the client http-Post request, (2) computes a complete new dataset (xml, up to 100 MB) using the fetched data and the requested function and parameters, (3) converts the dataset to the requested mime-type, (4) returns the resulting dataset as a response of the http-Post request to the client. If we would implement a simple server cache the process would be like this: (- client sends request via http-Post to the server) - server generates a unique key of the client http-Post request, because the URL of the http-Post request is always the same, - server checks if the unique key / filename is in the cache; no: normal process, - server checks via http-Head (origin server) if the cached data is fresh: no normal process, - server sends the cached data associated to the unique key / filename as response of the http-Post request to the client; end, - normal process: server fetches the data via http-Get; server computes the result dataset using the fetched data and the requested function and parameters; server stores data in cache; server sends the result data as response of the http-Post request to the client; end. I wonder if Squid could help us to cache the data accosiated to the client http-Post request. My idea is to generate a unique key of the http-Post request to make it cacheable. Thanks so much for your response. Farkas On 8 September 2012 04:48, Amos Jeffries <squid3@xxxxxxxxxxxxx> wrote: > 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
