persisting Response with HttpCore - implementing cache

[pluenl]

I've implemented a proxy application (using HttpClient 3.1) with some
manipulation logic.
 
Now I want to implement a cache for some requests/responses.
 
I've had a look in the API (and the mailing list) but could not find out how to
use HttpCore to create a Response-object, write it to the file system and
recreate the response for a later (cached) request from the file system.
 
What are the key classes to construct a Response without a socket from scratch
respectivly from file and how can I write the response (as serialized on a
socket stream) to a file parsing it again?
 
Thanks in advance,
Martin


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[olegk]

On Wed, 2008-06-04 at 07:07 +0200, pluenl wrote:
> I've implemented a proxy application (using HttpClient 3.1) with some
> manipulation logic.
>  
> Now I want to implement a cache for some requests/responses.
>  
> I've had a look in the API (and the mailing list) but could not find out how to
> use HttpCore to create a Response-object, write it to the file system and
> recreate the response for a later (cached) request from the file system.

Martin,

What is it exactly intend to cache? HTTP content body, content +
headers, raw data stream?

>  
> What are the key classes to construct a Response without a socket from scratch
> respectivly from file and how can I write the response (as serialized on a
> socket stream) to a file parsing it again?

The response head only:

http://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk/module-main/src/main/java/org/apache/http/impl/io/HttpResponseParser.java

In order to generate a complete response object with a content entity
you will have to extend this class:

http://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk/module-main/src/main/java/org/apache/http/impl/AbstractHttpClientConnection.html

You will also need to create mock input / output session buffers,
something similar to those:

http://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk/module-main/src/test/java/org/apache/http/mockup/SessionInputBufferMockup.java
http://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk/module-main/src/test/java/org/apache/http/mockup/SessionOutputBufferMockup.java

Hope this helps

Oleg


>  
> Thanks in advance,
> Martin
>




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[pluenl]

Oleg,

thank you for your help.
Sorry that I didn't answer yet, but my time was short so that I could
have a look at all only yesterday.

Am I right that HttpWriter/HttpParser only process the headers and the
message body writing/parsing is done via Entity(De)Serializer?

I adopted the Buffer-Mockups to use FileOutputStream but I do not use
the AbstractHttpClientConnection.

I think the code I've implemented by now does what I need, but can you
please just have a look if there is a potentially problem in my code
e.g. use of internal API that may change?

Thanks in advance
Martin  

Here's the code extract (writing and reading response only):

            String filename = "c:/temp/response.txt";

            EntitySerializer serializer = new EntitySerializer(new
StrictContentLengthStrategy());
            FileOutputStream fos = new FileOutputStream(filename);
            SessionOutputBufferMockup sobm = new
SessionOutputBufferMockup(fos);
            HttpResponseWriter writer = new HttpResponseWriter(sobm,
BasicLineFormatter.DEFAULT, new BasicHttpParams());
            writer.write(response);
            serializer.serialize(sobm, response, response.getEntity());
            fos.close();

            EntityDeserializer entityDeserializer = new
EntityDeserializer(new LaxContentLengthStrategy());
            FileInputStream fis = new FileInputStream(filename);
            SessionInputBufferMockup sibm = new
SessionInputBufferMockup(fis, 1024);
            HttpResponseParser responseParser = new HttpResponseParser(
                sibm,
                BasicLineParser.DEFAULT,
                new DefaultHttpResponseFactory(),
                new BasicHttpParams());
           
            response = (HttpResponse) responseParser.parse();
           
response.setEntity(entityDeserializer.deserialize(sibm,response));
            fis.close();

[olegk]

On Fri, 2008-06-27 at 07:28 +0200, pluenl wrote:
> Oleg,
>
> thank you for your help.
> Sorry that I didn't answer yet, but my time was short so that I could
> have a look at all only yesterday.
>
> Am I right that HttpWriter/HttpParser only process the headers and the
> message body writing/parsing is done via Entity(De)Serializer?
>

Yes, you are.

> I adopted the Buffer-Mockups to use FileOutputStream but I do not use
> the AbstractHttpClientConnection.
>
> I think the code I've implemented by now does what I need, but can you
> please just have a look if there is a potentially problem in my code
> e.g. use of internal API that may change?
>

Looks all right to me

Oleg

> Thanks in advance
> Martin  
>
> Here's the code extract (writing and reading response only):
>
>             String filename = "c:/temp/response.txt";
>
>             EntitySerializer serializer = new EntitySerializer(new
> StrictContentLengthStrategy());
>             FileOutputStream fos = new FileOutputStream(filename);
>             SessionOutputBufferMockup sobm = new
> SessionOutputBufferMockup(fos);
>             HttpResponseWriter writer = new HttpResponseWriter(sobm,
> BasicLineFormatter.DEFAULT, new BasicHttpParams());
>             writer.write(response);
>             serializer.serialize(sobm, response, response.getEntity());
>             fos.close();
>
>             EntityDeserializer entityDeserializer = new
> EntityDeserializer(new LaxContentLengthStrategy());
>             FileInputStream fis = new FileInputStream(filename);
>             SessionInputBufferMockup sibm = new
> SessionInputBufferMockup(fis, 1024);
>             HttpResponseParser responseParser = new HttpResponseParser(
>                 sibm,
>                 BasicLineParser.DEFAULT,
>                 new DefaultHttpResponseFactory(),
>                 new BasicHttpParams());
>            
>             response = (HttpResponse) responseParser.parse();
>            
> response.setEntity(entityDeserializer.deserialize(sibm,response));
>             fis.close();

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