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Class w3c.jigsaw.resources.NegotiatedResource 

java.lang.Object
   |
   +----w3c.tools.store.AttributeHolder
           |
           +----w3c.tools.store.Resource
                   |
                   +----w3c.jigsaw.resources.HTTPResource
                           |
                           +----w3c.jigsaw.resources.FilteredResource
                                   |
                                   +----w3c.jigsaw.resources.NegotiatedResource
public class NegotiatedResource
extends FilteredResource
This class provides content negociation among any other resources. This resource tries to conform to the HTTP/1.0 specification of content negociation.

A bit of terminology here: in HTTP terms, a resource should negotiate among a set of entities, not among a set of variants. Jigsaw uses the term resource as an object able to respond to HTTP requests, and so is able to negotiate among resources (eg it can negotiate among a CGIResource, a FileResource of whatever other resources).

Variable Index

o ATTR_VARIANTS
Attribute index - The set of names of variants.
o VARY
The Vary header field for this resource is always the same.

Constructor Index

o NegotiatedResource()

Method Index

o getVariantNames()
Get the variant names.
o getVariantResources()
Get the variant resources.
o negotiate(Request)
Negotiate among the various variants for the Resource.
o negotiateCharsetQuality(Vector, Request)
Negotiate on charsets.
o negotiateContentEncoding(Vector, Request)
Negotiate among content encodings.
o negotiateContentType(Vector, Request)
Negotiate among content types.
o negotiateLanguageQuality(Vector, Request)
Negotiate among language qualities.
o perform(Request)
Perform an HTTP request.
o printNegotiationState(String, Vector)
Print the current negotiation state.

Variables

o VARY 
 protected static HttpTokenList VARY
The Vary header field for this resource is always the same.

o ATTR_VARIANTS 
 protected static int ATTR_VARIANTS
Attribute index - The set of names of variants.

Constructors

o NegotiatedResource 
 public NegotiatedResource()

Methods

o getVariantNames 
 public String[] getVariantNames()
Get the variant names.

o getVariantResources 
 public HTTPResource[] getVariantResources() throws HTTPException
Get the variant resources. This is somehow broken, it shouldn't allocate the array of variants on each call. However, don't forget that the list of variants can be dynamically edited, this means that if we are to keep a cache of it (as would be the case if we kept the array of variants as instance var) we should also take care of editing of attributes (possible, but I just don't have enough lifes).

Returns:
An array of HTTPResource, or null.
Throws: HTTPException
If one of the variants doesn't exist.
o printNegotiationState 
 protected void printNegotiationState(String header,
                                      Vector states)
Print the current negotiation state.

Parameters:
header - The header to print first.
states - The current negotiation states.
o negotiateContentEncoding 
 protected boolean negotiateContentEncoding(Vector states,
                                            Request request) throws HTTPException
Negotiate among content encodings.

BUG: This will work only for single encoded variants.

Parameters:
states - The current negotiation states.
request - The request to handle.
o negotiateCharsetQuality 
 protected boolean negotiateCharsetQuality(Vector states,
                                           Request request)
Negotiate on charsets.

BUG: Not implemented yet.

Parameters:
states - The current states of negotiation.
request - The request to handle.
o negotiateLanguageQuality 
 protected boolean negotiateLanguageQuality(Vector states,
                                            Request request) throws HTTPException
Negotiate among language qualities.

BUG: This will only work for variants that have one language tag.

Parameters:
states - The current states of negotiation.
request - The request to handle.
o negotiateContentType 
 protected boolean negotiateContentType(Vector states,
                                        Request request) throws HTTPException
Negotiate among content types.

Parameters:
states - The current states of negotiation.
request - The request to handle.
o negotiate 
 protected HTTPResource negotiate(Request request) throws HTTPException
Negotiate among the various variants for the Resource. We made our best efforts to be as compliant as possible to the HTTP/1.0 content negotiation algorithm.

o perform 
 public Reply perform(Request request) throws HTTPException, ClientException
Perform an HTTP request. Negotiate among the variants, the best variant according to the request fields, and make this elect3d variant serve the request.

Parameters:
request - The request to handle.
Throws: HTTPException
If negotiating among the resource variants failed.
Overrides:
perform in class HTTPResource 
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