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# Wx::DDEConnection

A DDEConnection object represents the connection between a client and a
server. It can be created by making a connection using a DDEClient object, or by the acceptance of a connection by a DDEServer object. The bulk of a DDE (Dynamic Data Exchange)
conversation is controlled by
calling members in a DDEConnection object or by overriding its
members.

An application should normally derive a new connection class from
DDEConnection, in order to override the communication event handlers
to do something interesting.

This DDE-based implementation is available on Windows only,
but a platform-independent, socket-based version
of this API is available using TCPConnection.

## Derived from

ConnectionBase

Object

## Types

IPCFormatIPCFormat is defined as follows:

enum IPCFormat { IPC_INVALID = 0, IPC_TEXT = 1, /* CF_TEXT */ IPC_BITMAP = 2, /* CF_BITMAP */ IPC_METAFILE = 3, /* CF_METAFILEPICT */ IPC_SYLK = 4, IPC_DIF = 5, IPC_TIFF = 6, IPC_OEMTEXT = 7, /* CF_OEMTEXT */ IPC_DIB = 8, /* CF_DIB */ IPC_PALETTE = 9, IPC_PENDATA = 10, IPC_RIFF = 11, IPC_WAVE = 12, IPC_UNICODETEXT = 13, IPC_ENHMETAFILE = 14, IPC_FILENAME = 15, /* CF_HDROP */ IPC_LOCALE = 16, IPC_PRIVATE = 20 };

## See also

DDEClient, DDEServer, Interprocess communications overview

## Methods

- DDEConnection.new
- DDEConnection#advise
- DDEConnection#execute
- DDEConnection#disconnect
- DDEConnection#on_advise
- DDEConnection#on_disconnect
- DDEConnection#on_execute
- DDEConnection#on_poke
- DDEConnection#on_request
- DDEConnection#on_start_advise
- DDEConnection#on_stop_advise
- DDEConnection#poke
- DDEConnection#request
- DDEConnection#start_advise
- DDEConnection#stop_advise

### DDEConnection.new

DDEConnection.new(%(arg-type)char% buffer, Integer size)

Constructs a connection object. If no user-defined connection object is
to be derived from DDEConnection, then the constructor should not be
called directly, since the default connection object will be provided on
requesting (or accepting) a connection. However, if the user defines his
or her own derived connection object, the DDEServer#on_accept_connection and/or DDEClient#on_make_connection members should be replaced by
functions which construct the new connection object. If the arguments of
the DDEConnection constructor are void, then a default buffer is
associated with the connection. Otherwise, the programmer must provide a
a buffer and size of the buffer for the connection object to use in
transactions.

### DDEConnection#advise

Boolean advise(%(arg-type)String% item, char data, Integer size = -1, IPCFormat format = CF_TEXT)

Called by the server application to advise the client of a change in
the data associated with the given item. Causes the client
connection’s DDEConnection#on_advise
member to be called. Returns true if successful.

### DDEConnection#execute

Boolean execute(%(arg-type)char% data, Integer size = -1, IPCFormat format = CF_TEXT)

Called by the client application to execute a command on the server. Can
also be used to transfer arbitrary data to the server (similar
to DDEConnection#poke in that respect). Causes the
server connection’s DDEConnection#on_execute member to be
called. Returns true if successful.

### DDEConnection#disconnect

Boolean disconnect()

Called by the client or server application to disconnect from the other
program; it causes the DDEConnection#on_disconnect message
to be sent to the corresponding connection object in the other
program. The default behaviour of OnDisconnect is to delete the
connection, but the calling application must explicitly delete its
side of the connection having called Disconnect. Returns true if
successful.

### DDEConnection#on_advise

Boolean on_advise(%(arg-type)String% topic, String item, char data, Integer size, IPCFormat format)

Message sent to the client application when the server notifies it of a
change in the data associated with the given item.

### DDEConnection#on_disconnect

Boolean on_disconnect()

Message sent to the client or server application when the other
application notifies it to delete the connection. Default behaviour is
to delete the connection object.

### DDEConnection#on_execute

Boolean on_execute(%(arg-type)String% topic, char data, Integer size, IPCFormat format)

Message sent to the server application when the client notifies it to
execute the given data. Note that there is no item associated with
this message.

### DDEConnection#on_poke

Boolean on_poke(%(arg-type)String% topic, String item, char data, Integer size, IPCFormat format)

Message sent to the server application when the client notifies it to
accept the given data.

### DDEConnection#on_request

char on_request(%(arg-type)String% topic, String item, Integer size, IPCFormat format)

Message sent to the server application when the client
calls DDEConnection#request. The server
should respond by returning a character string from OnRequest,
or NULL to indicate no data.

### DDEConnection#on_start_advise

Boolean on_start_advise(%(arg-type)String% topic, String item)

Message sent to the server application by the client, when the client
wishes to start an `advise loop’ for the given topic and item. The
server can refuse to participate by returning false.

### DDEConnection#on_stop_advise

Boolean on_stop_advise(%(arg-type)String% topic, String item)

Message sent to the server application by the client, when the client
wishes to stop an `advise loop’ for the given topic and item. The
server can refuse to stop the advise loop by returning false, although
this doesn’t have much meaning in practice.

### DDEConnection#poke

Boolean poke(%(arg-type)String% item, char data, Integer size = -1, IPCFormat format = CF_TEXT)

Called by the client application to poke data into the server. Can be
used to transfer arbitrary data to the server. Causes the server
connection’s DDEConnection#on_poke member
to be called. Returns true if successful.

### DDEConnection#request

char request(%(arg-type)String% item, Integer size, IPCFormat format = IPC_TEXT)

Called by the client application to request data from the server. Causes
the server connection’s DDEConnection#on_request member to be called. Returns a
character string (actually a pointer to the connection’s buffer) if
successful, NULL otherwise.

### DDEConnection#start_advise

Boolean start_advise(%(arg-type)String% item)

Called by the client application to ask if an advise loop can be started
with the server. Causes the server connection’s DDEConnection#on_start_advise member to be called. Returns true if the server okays it, false
otherwise.

### DDEConnection#stop_advise

Boolean stop_advise(%(arg-type)String% item)

Called by the client application to ask if an advise loop can be
stopped. Causes the server connection’s DDEConnection#on_stop_advise member
to be called. Returns true if the server okays it, false otherwise.

[This page automatically generated from the Textile source at 2023-06-09 00:45:25 +0000]