HP NonStop G-Series - Manual (Page 13)

1 Introduction to the Tandem
DDE Gateway
110838 Tandem Computers Incorporated 1–1
The Tandem DDE (Dynamic Data Exchange) Gateway allows Windows applications
to use the DDE protocol to communicate with Tandem Pathway server classes and
Guardian processes through the Tandem Remote Server Call (RSC). Figure 1-1 shows
the DDE environment.
Figure 1-1. Tandem DDE Gateway Components
Standard
DDE
Protocol
Windows
Workstation
Tandem
System
Client
Application
Client
Application
Pathway
Server Class
Remote
Server Call
Tandem DDE
Gateway
Guardian
Process
001
DDE RSC
Transaction
Delivery
Process
DDE is a Microsoft standard message protocol for dynamically exchanging data
between Windows applications. You can use DDE to create Tandem DDE Gateway
client applications by using many Windows applications and tools, including
Microsoft Visual Basic, Microsoft Excel, Microsoft Word for Windows, the C
programming language, and Powersoft PowerBuilder.
Remote Server Call (RSC) provides connectivity from the workstation to the Tandem
system over a number of data communications protocols, including NetBIOS, TCP/IP,
and asynchronous. By supporting DDE, the Tandem DDE Gateway allows a wide
range of Windows applications and tools from many software publishers to
communicate with Pathway server classes and Guardian processes over many data
communications protocols. Generally no tool customization or custom interface
libraries is required.
The Tandem DDE Gateway establishes data communication connections and shares
them among Windows applications. This feature allows the client applications to start
and stop without regard to the communications implications. Client application
developers do not need to be concerned with managing the communications
connections—this is done by the Tandem DDE Gateway.
The Tandem DDE Gateway completely insulates the client application developer from
data communications related programming. Client applications use DDE to
communicate with Tandem servers in the same way they would use DDE to
communicate with another Windows application such as Microsoft Excel.