Girish
Start at the Programming section in InfoCenter. There's a subsection on
APIs (& CL, I think). The API Programming manual is there, as well a number
of examples in various languages. Be sure to study the API Concepts section.
All the APIs are documented for use with C or C++. You'll need to get used
to that syntax to understand better what they do. There are, however, a
number of /COPY members for RPG and RPGLE in library QSYSINC. Some (in
RPG/LE) you can use as is, others you may need to make a copy and add the
non-fixed length parts. C can include a structure inside one of your own -
AFAIK RPG/LE cannot do this - others may know better. This ability lets you
not worry about release changes as much.
Very little is documented about using CL/LE for APIs, but it works quite
well for those that use a user space or return data in a variable.
The documentation in InfoCenter includes API Concepts. Get to know user
spaces very well, and how they are used in APIs.
If you use RPG/LE, learn about pointers - you'll have a much easier time of
it. And you can have a pointer to a user space in RPG, allowing for
automatic growth of what amounts to a character (or hex) buffer.
I agree with Al, to a point, that APIs are tough. But not all of them are.
All they are is programs or service programs. The interface is defined, and
you need to be careful to follow it exactly. But that's nothing new for
anything we get from another developer. Once you get your feet a little
wet, you'll be fine.
Some are definitely complex - the retrieve file description & query APIs
are daunting, and almost impossible in RPG, since they are so dependent on
pointers, and nested structures. Spooled file APIs, which offer a lot of
functionality, are really a pain.
Enjoy!
Vern
At 06:37 PM 1/30/2003 -0500, you wrote:
Could anyone suggest a good reference web site for using API's. I see soem
great ones referenced but wanted to see what else is
available what parametrs to use, any systems requirements and then (if
I'm not asking for too much already ) examples...
thanks in advance...
Girish
midrange.com
