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# QCopEnvelope Class Reference

The QCopEnvelope class encapsulates and sends QCop messages over QCopChannels. More...

`#include <qtopia/qcopenvelope_qws.h>`

Inherits QDataStream.

List of all member functions.

## Public Members

- QCopEnvelope ( const QCString & channel, const QCString & message )
- ~QCopEnvelope ()

## Detailed Description

The QCopEnvelope class encapsulates and sends QCop messages over QCopChannels.

QCop messages allow applications to communicate with each other. These messages are sent using QCopEnvelope, and received by connecting to a QCopChannel.

To send a message, use the following protocol:

         QCopEnvelope e(channelname, messagename);
         e << parameter1 << parameter2 << ...;

For messages without parameters, simply use:

         QCopEnvelope e(channelname, messagename);

(Do not try to simplify this further as it may confuse some compilers.)

The `channelname` of channels within Qtopia all start with "QPE/". The `messagename` is a function identifier followed by a list of types in parentheses. There is no whitespace in the message name.

To receive a message, you will generally just use your application's predefined QPE/Application/appname channel (see QPEApplication::appMessage()), but you can make another channel and connect it to a slot like this:

          myChannel = new QCopChannel( "QPE/FooBar", this );
          connect( myChannel, SIGNAL(received(const QCString &, const QByteArray &)),
                   this, SLOT(fooBarMessage( const QCString &, const QByteArray &)) );

See also, the list of Qtopia messages.

See also Qtopia Classes.

## Member Function Documentation

### QCopEnvelope::QCopEnvelope ( const QCString & channel, const QCString & message )

Constructs a QCopEnvelope that will write message to channel. If message has parameters, you must then use operator<<() to add these parameters to the envelope.

### QCopEnvelope::~QCopEnvelope ()

Writes the message and then destroys the QCopEnvelope.

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