Wt::WResource Class Reference

An object which can be rendered in the HTTP protocol. More...

#include <Wt/WResource>

Inheritance diagram for Wt::WResource:

Inheritance graph
[legend]

List of all members.

Public Member Functions

 WResource (WObject *parent=0)
 Create a new resource.
 ~WResource ()
 Destroy the resource.
void suggestFileName (const std::string &name)
 Suggest a filename to the user for the data streamed by this resource.
const std::string generateUrl () const
 Generate an URL for this resource.
bool reentrant () const
 Can this resource be streamed reentrantly ?
void setReentrant (bool reentrant)
 Specify if this resource may be streamed reentrantly.
void write (std::ostream &out)
 Stream the resource to a stream.

Public Attributes

Signal< void > dataChanged
 Emit this signal if the data presented in this resource has changed.

Protected Member Functions

virtual const std::string resourceMimeType () const =0
 Return the mimetype.
virtual bool streamResourceData (std::ostream &stream, const ArgumentMap &arguments)=0
 Stream the data for this resource.
void flush ()
 Flush data for this resource.
virtual void setArguments (const ArgumentMap &arguments)
 Set the arguments.
void addHeader (const std::string &name, const std::string &value)
 Add a HTTP header.


Detailed Description

An object which can be rendered in the HTTP protocol.

Besides the main page, other objects may be rendered as additional resources, such as frames or dynamic images.


Constructor & Destructor Documentation

Wt::WResource::~WResource (  ) 

Destroy the resource.

It is up to the user to make sure that the resource is nog longer in use.


Member Function Documentation

void Wt::WResource::suggestFileName ( const std::string &  name  ) 

Suggest a filename to the user for the data streamed by this resource.

For resources, intended to be downloaded by the user, suggest a name used for saving. The extension will help the browser to identify the correct program for opening the resource as well.

const std::string Wt::WResource::generateUrl (  )  const

Generate an URL for this resource.

For every call, a new url is generated that refers to this resource. The url is unique to assure that it is not cached by the web browser. Therefore, when the signal dataChanged() is emitted, the widget that uses this resource should call generateUrl() to refer to the changed version of this resource.

bool Wt::WResource::reentrant (  )  const [inline]

Can this resource be streamed reentrantly ?

Reentrant resources may be streamed concurrently to the user. Thus, its resourceMimeType() and streamResourceData() functions must be implemented in a thread-safe way.

See also:
setReentrant()

void Wt::WResource::setReentrant ( bool  reentrant  ) 

Specify if this resource may be streamed reentrantly.

A reentrant resource may stream its data concurrently with other resources (and with the main event handling ? perhaps this is not necessary...)

See also:
reentrant()

void Wt::WResource::write ( std::ostream &  out  ) 

Stream the resource to a stream.

This is a convenience method to serialize to a stream (for example a files stream).

virtual const std::string Wt::WResource::resourceMimeType (  )  const [protected, pure virtual]

Return the mimetype.

Implement this method to return the correct mime type for your resource, e.g. "text/html".

Implemented in Wt::Ext::DataStore, Wt::WFileResource, Wt::WMemoryResource, Wt::WSvgImage, and Wt::WWidget.

virtual bool Wt::WResource::streamResourceData ( std::ostream &  stream,
const ArgumentMap &  arguments 
) [protected, pure virtual]

Stream the data for this resource.

Implement this method to output the data for this resource.

Returns whether all data has been streamed. If not, call flush() from outside the mean event loop to indicate that more data is available. This is how "server-push" is implemented. The stream is not closed until this function returns true.

See also:
flush()

void Wt::WResource::flush (  )  [protected]

Flush data for this resource.

This is only valid when a previous call to streamResourceData() returned false.

This will trigger a call to streamResourceData() to retrieve more data to be transmitted.

See also:
streamResourceData()

void Wt::WResource::setArguments ( const ArgumentMap &  arguments  )  [protected, virtual]

Set the arguments.

This method is called before asking reosurceMimeType() and calling streamResourceData() (with the same arguments repeated).

The default implementation does nothing.

void Wt::WResource::addHeader ( const std::string &  name,
const std::string &  value 
) [protected]

Add a HTTP header.

This may only be called from within the setArguments(), and not from within streamResourceData() !


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