About this chapter
This chapter describes how PowerBuilder supports DDE.
Dynamic Data Exchange (DDE) makes it possible for two Windows applications to communicate with each other by sending and receiving commands and data. Using DDE, the applications can share data, execute commands remotely, and check error conditions.
PowerBuilder supports DDE by providing PowerScript events and functions that enable a PowerBuilder application to send messages to other DDE-supporting applications and to respond to DDE requests from other DDE applications.
Clients and servers
A DDE-supporting application can act as either a client or a server.
About the terminology
Used in connection with DDE, these terms are not related to client/server architecture, in which a PC or workstation client communicates with a database server.
A client application makes requests of another DDE-supporting application (called the server). The requests can be commands (such as open, close, or save) or requests for data.
A server application is the opposite of a client application. It responds to requests from another DDE-supporting application (called the client). As with client applications, the requests can be commands or requests for specific data.
A PowerBuilder application can function as a DDE client or as a DDE server.
In PowerBuilder, DDE clients and servers call built-in functions and process events. DDE events occur when a command or data is sent from a client to a server (or from a server to a client).
The following tables list the DDE functions and events separated into those functions and events used by DDE clients and those used by DDE servers. For more information on DDE support, see the PowerScript Reference.
Return values
Every DDE function returns an integer.
DDE client
|
Function |
Action |
|---|---|
|
CloseChannel |
Closes a channel to a DDE server application that was opened using OpenChannel. |
|
ExecRemote |
Asks a DDE server application to execute a command. |
|
GetDataDDE |
Obtains the new data from a hot-linked DDE server application and moves it into a specified string. |
|
GetDataDDEOrigin |
Determines the origin of data that has arrived from a hot-linked DDE server application. |
|
GetRemote |
Asks a DDE server application for data. This function has two formats: one that uses a channel and one that does not. |
|
OpenChannel |
Opens a DDE channel to a specified DDE server application. |
|
RespondRemote |
Indicates to the DDE server application whether the command or data received from the DDE application was acceptable to the DDE client. |
|
SetRemote |
Asks a DDE server application to set an item such as a cell in a worksheet or a variable to a specific value. This function has two formats: one that uses a DDE channel and one that does not. |
|
StartHotLink |
Initiates a hot link to a DDE server application so that PowerBuilder is immediately notified of specific data changes in the DDE server application. |
|
StopHotLink |
Ends a hot link with a DDE server application. |
DDE server
|
Function |
Action |
|---|---|
|
GetCommandDDE |
Obtains the command sent by a DDE client application |
|
GetCommandDDEOrigin |
Determines the origin of a command from a DDE client |
|
GetDataDDE |
Gets data that a DDE client application has sent and moves it into a specified string |
|
GetDataDDEOrigin |
Determines the origin of data that has arrived from a hot-linked DDE client application |
|
RespondRemote |
Indicates to the sending DDE client application whether the command or data received from the DDE application was acceptable to the DDE server |
|
SetDataDDE |
Sends specified data to a DDE client application |
|
StartServerDDE |
Causes a PowerBuilder application to begin acting as a DDE server |
|
StopServerDDE |
Causes a PowerBuilder application to stop acting as a DDE server |
|
Event |
Occurs when |
|---|---|
|
RemoteExec |
A DDE client application has sent a command |
|
RemoteHotLinkStart |
A DDE client application wants to start a hot link |
|
RemoteHotLinkStop |
A DDE client application wants to end a hot link |
|
RemoteRequest |
A DDE client application has requested data |
|
RemoteSend |
A DDE client application has sent data |
