Wt::WStreamResource Class Reference

An object which streams the data from a std::istream. More...

#include <Wt/WStreamResource>

Inheritance diagram for Wt::WStreamResource:

Public Member Functions
	WStreamResource (WObject *parent=0)
	Default constructor.
	WStreamResource (const std::string &mimeType, WObject *parent=0)
	Creates a new resource with given mime-type.
	~WStreamResource ()
	Destructor.
void	setMimeType (const std::string &mimeType)
	Sets the mime-type.
const std::string &	mimeType () const
	Returns the mime-type.
void	setBufferSize (int size)
	Configures the buffer size.
int	bufferSize () const
	Returns the buffer size.
Public Member Functions inherited from Wt::WResource
	WResource (WObject *parent=0)
	Creates a new resource.
	~WResource ()
	Destroys the resource.
void	suggestFileName (const Wt::WString &name, DispositionType dispositionType=Attachment)
	Suggests a filename to the user for the data streamed by this resource.
const Wt::WString &	suggestedFileName () const
	Returns the suggested file name.
void	setDispositionType (DispositionType cd)
	Configures the Content-Disposition header.
DispositionType	dispositionType () const
	Returns the currently configured content disposition.
void	setChanged ()
	Generates a new URL for this resource and emits the changed signal.
void	setInternalPath (const std::string &path)
	Sets an internal path for this resource.
std::string	internalPath () const
	Returns the internal path.
const std::string &	generateUrl ()
	Generates an URL for this resource.
const std::string &	url () const
	Returns the current URL for this resource.
Signal &	dataChanged ()
	Signal emitted when the data presented in this resource has changed.
void	setUploadProgress (bool enabled)
	Indicate interest in upload progress.
Signal< ::uint64_t,::uint64_t > &	dataReceived ()
	Signal emitted when data has been received for this resource.
void	write (std::ostream &out, const Http::ParameterMap &parameters=Http::ParameterMap(), const Http::UploadedFileMap &files=Http::UploadedFileMap())
	Stream the resource to a stream.
virtual void	handleRequest (const Http::Request &request, Http::Response &response)=0
	Handles a request.
void	haveMoreData ()
	Indicate that more data is available.
Public Member Functions inherited from Wt::WObject
	WObject (WObject *parent=0)
	Create a WObject with a given parent object.
virtual	~WObject ()
	Destructor.
virtual const std::string	id () const
	Returns the (unique) identifier for this object.
void	setObjectName (const std::string &name)
	Sets an object name.
virtual std::string	objectName () const
	Returns the object name.
void	resetLearnedSlots ()
	Resets learned stateless slot implementations.
template<class T >
void	resetLearnedSlot (void(T::*method)())
	Resets a learned stateless slot implementation.
template<class T >
WStatelessSlot *	implementStateless (void(T::*method)())
	Declares a slot to be stateless and learn client-side behaviour on first invocation.
template<class T >
WStatelessSlot *	implementStateless (void(T::*method)(), void(T::*undoMethod)())
	Declares a slot to be stateless and learn client-side behaviour in advance.
template<class T >
WStatelessSlot *	implementJavaScript (void(T::*method)(), const std::string &jsCode)
	Provides a JavaScript implementation for a method.
void	addChild (WObject *child)
	Adds a child object.
virtual void	removeChild (WObject *child)
	Removes a child object.
const std::vector< WObject * > &	children () const
	Returns the children.
WObject *	parent () const
	Returns the parent object.

Protected Member Functions
void	handleRequestPiecewise (const Http::Request &request, Http::Response &response, std::istream &input)
	Handles a request and streams the data from a std::istream.
Protected Member Functions inherited from Wt::WResource
void	beingDeleted ()
	Prepares the resource for deletion.
Protected Member Functions inherited from Wt::WObject
virtual WStatelessSlot *	getStateless (Method method)
	On-demand stateless slot implementation.

Additional Inherited Members
Public Types inherited from Wt::WResource
enum	DispositionType { NoDisposition, Attachment, Inline }
	Values for the disposition type in the Content-Disposition header. More...
Static Protected Member Functions inherited from Wt::WObject
static WObject *	sender ()
	Returns the sender of the current slot call.

Detailed Description

An object which streams the data from a std::istream.

This class can be useful base for implementing resources which streams the data from std::istream derivatives.

The utility method handleRequestPiecewise() makes use of continuations to transmit data piecewise, without blocking a thread or requiring the whole data to be read in memory. The size of the buffer can be changed by using setBufferSize().

Example for a custom stream resource implementation:

class MyStreamResource : public Wt::WStreamResource
{
public:
  MyStreamResource(const std::string& fileName, Wt::WObject *parent = 0)
    : Wt::WStreamResource(parent),
      fileName_(fileName)
  {
    suggestFileName("data.txt");
  }

  ~MyStreamResource() {
    beingDeleted();
  }

  void handleRequest(const Wt::Http::Request& request,
                     Wt::Http::Response& response) {
    std::ifstream r(fileName_.c_str(), std::ios::in | std::ios::binary);
    handleRequestPiecewise(request, response, r);
  }

private:
  std::string fileName_;
};

See Also

WFileResource

Constructor & Destructor Documentation

Wt::WStreamResource::WStreamResource

(

WObject *

parent = 0

)

Default constructor.

The mime type defaults to "text/plain".

Wt::WStreamResource::~WStreamResource

(

)

Destructor.

It is up to the user to make sure that the resource is no longer in use (by e.g. a WImage).

Member Function Documentation

int Wt::WStreamResource::bufferSize

(

)

const

Returns the buffer size.

See Also

setBufferSize()

void Wt::WStreamResource::handleRequestPiecewise ( const Http::Request &  request, Http::Response &  response, std::istream &  input  )

protected

Handles a request and streams the data from a std::istream.

You can call this method from a custom handleRequest() implementations.

void Wt::WStreamResource::setBufferSize

(

int

size

)

Configures the buffer size.

This configures the size of the buffer used to transmit the data piece by piece.