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OS/2 Shareware BBS: 16 Announce
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16-Announce.zip
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MIRDEF.ZIP
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MIRDEF.DOC
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1992-05-12
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71 lines
Many of you have asked about Mirrors -- What is it? How does it work?
How do I use it? Where do I get it? What follows is a bit more
detailed description about how Mirrors works.
How Mirrors Works
First, let's review the architecture and environment in which
applications running under OS/2 and Windows operate. They are
similar.
An application in both environments typically consists of code which
is designed to process event driven messages as input. Frequently
these messages cause the application to use system resources
which reside in dynamic linked libraries, such as functions to render
graphic output or access the file system. The use of these system
capabilities is provided by way of function calls which are exported
from various system DLLs.
Both development environments locate a number of necessary items
in separate files. These include application icons, bit maps, help files,
and other things. Here again there is a strong similarity between the
structure of the two environments. Although a PM application cannot
directly use a Windows icon, the process of translating one into the
other is relatively simple. Translation of these resources is done
once, before the application is linked, by a set of conversion utilities
provided by Mirrors.
The similarity of both architectures and the nature of dynamically
linked libraries are the conditions which enable Mirrors to empower
Windows applications to run under OS/2. The Windows application,
which has been ported to OS/2, continues to make calls to what it
believes to be the Windows system DLLs. However, these calls are
intercepted by the Mirrors DLLs which then passes the call on to the
appropriate export within the OS/2 system DLLs or implements the
equivalent functionality using the PM API. For instance, Windows
dialog boxes and control classes are implemented entirely by Mirrors.
Components of Mirrors
Mirrors has two principle components: DLLs and static conversion
utilities.
The static conversion utilities are simple command
line utilities. Using them is simple. For instance, to convert
a Windows Definition File to a PM Definition File you would issue
a command like: MIRDEF INPUT.DEF OUTPUT.DEF.
It's as easy as that. The utility will run and produce a PM Def
file for your application.
The other component of the Mirrors toolkit are its DLL files,
which are OS/2 Presentation Manager dynamic link libraries. These
allow a Windows application to run virtually unchanged under the
Presentation Manager.
Mirrors acts as a filter between the Windows application code and the
Presentation Manager. Mirrors emulates Windows by defining all of
the necessary Windows functions in the Mirrors DLL. When an
application calls a Windows function, Mirrors accepts the call and the
parameters passed with it. Mirrors then implements the function using
the functions within the OS/2 system DLLs.
Where to Get Mirrors
Though developed by Micrografx, Mirrors will be avaialable from IBM.
Call whatever number you usually do to find out about IBM developers
kits and so forth. I don't give a number here because this
message will probably travel internationally and those numbers
vary from place to place.
Yours, Derrel R. Blain, Micrografx