DLL Programmer's Guide for TNS/R Systems

DLLs on a TNS/R System
DLL Programmer’s Guide for TNS/R Systems—522203-002
1-5
Building and Loading Programs and Libraries
•
The same program can run simultaneously in different processes with different
DLLs supplying the supporting data and functions.
•
A new version of a DLL can be introduced without having to alter a program or DLL
that references it, even though the location of the referenced sites has changed.
This gives you great freedom to change a DLL.
•
A program and the DLLs loaded with it at process creation time can access each
other’s functions and data do so by simply referencing their symbolic names.
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A running application can cause a DLL to be loaded dynamically and to make its
functions and data accessible.
Building and Loading Programs and Libraries
Generating an Executable Load Image
Figure 1-3 on page 1-6 shows the steps for going from a source file to an executable
PIC load image. The compiler translates a source code file into a linkable code file,
called a linkfile. The linker brings together one or more linkfiles to create a loadfile,
which can be designated as either a program or a DLL.
Finally, at load time, the loader determines the arrangement of the libraries in virtual
memory, resolves references among loadfiles, and loads the program and libraries for
execution. Your application can also cause DLLs to be loaded after the program has
been loaded and put into execution.