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Class org.w3c.jigsaw.frames.NegotiatedFrame

java.lang.Object
   |
   +----org.w3c.tools.resources.AttributeHolder
           |
           +----org.w3c.tools.resources.Resource
                   |
                   +----org.w3c.tools.resources.FramedResource
                           |
                           +----org.w3c.tools.resources.ResourceFrame
                                   |
                                   +----org.w3c.tools.resources.ProtocolFrame
                                           |
                                           +----org.w3c.jigsaw.frames.HTTPFrame
                                                   |
                                                   +----org.w3c.jigsaw.frames.NegotiatedFrame

public class NegotiatedFrame
extends HTTPFrame
Content negotiation.


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 NegotiatedFrame()

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(RequestInterface)
Perform an HTTP request.
 o printNegotiationState(String, Vector)
Print the current negotiation state.
 o registerResource(FramedResource)
Register this frame to the given resource.
 o setVariants(String[])

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 NegotiatedFrame
 public NegotiatedFrame()

Methods

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

 o setVariants
 public void setVariants(String variants[])
 o getVariantResources
 public ResourceReference[] getVariantResources() throws ProtocolException
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 ResourceReference, or null.
Throws: ProtocolException
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 ProtocolException
Negotiate among content encodings.

BUG: This will work only for single encoded variants.

Parameters:
states - The current negotiation states.
request - The request to handle.
Returns:
a boolean.
Throws: ProtocolException
If one of the variants doesn't exist.
 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 ProtocolException
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.
Returns:
a boolean.
Throws: ProtocolException
If one of the variants doesn't exist.
 o negotiateContentType
 protected boolean negotiateContentType(Vector states,
                                        Request request) throws ProtocolException
Negotiate among content types.

Parameters:
states - The current states of negotiation.
request - The request to handle.
Returns:
a boolean.
Throws: ProtocolException
If one of the variants doesn't exist.
 o negotiate
 protected ResourceReference negotiate(Request request) throws ProtocolException
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.

Parameters:
request - the incomming request.
Returns:
a RefourceReference instance.
Throws: ProtocolException
If one of the variants doesn't exist.
 o registerResource
 public void registerResource(FramedResource resource)
Register this frame to the given resource.

Overrides:
registerResource in class HTTPFrame
 o perform
 public ReplyInterface perform(RequestInterface req) throws ProtocolException, ResourceException
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: ProtocolException
If negotiating among the resource variants failed.
Throws: ResourceException
If the resource got a fatal error.
Overrides:
perform in class HTTPFrame

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