7. Using the library
********************
XML/Ada is a library. When compiling an application that uses it, you
thus need to declare this dependency. The default installation implies
the use of GNAT project files. See the GPRbuild and GPR Companion
Tools User’s Guide for more information on the project files and how
to create them for your application.
Basically, a project file contains the description of your build
environment (source directories, object directories, libraries, etc).
The very simple case is when you have all your sources in the same
directory (say "src/"), and the object files are all generated in the
"obj/" directory.
In this case, your project file would look like:
with "xmlada";
project Default is
for Source_Dirs use ("src/");
for Object_Dir use "obj/";
end Default;
and you build your application with:
gprbuild -Pdefault main.adb
Note in the project file the first line, which indicates that your
application requires XML/Ada to build. This will automatically set the
appropriate compiler and linker switches to use XML/Ada. Your
application will be linked against all modules of XML/Ada (DOM, SAX…).
If your application doesn’t use DOM, you can replace the first line
with something like:
with "xmlada_sax";
which will reduce the number of libraries that your application is
linked with.
If the installation prefix is the same as your GNAT installation
(which is the case of the preinstalled version of the library), then
GPRbuild will automatically find XML/Ada’s project files. If XML/Ada
is not installed into a predefined location (e.g. because you rebuilt
it from sources), you need to let GPRbuild know where to find the
project files. This is done by setting the *GPR_PROJECT_PATH*
environment variable, by adding to it the directory that contains
"xmlada.gpr".
Check the "dom/test" directory in the XML/Ada package, which contains
both code examples and project files that you can use as a basis for
your own code.
The default type of library depends on the way you installed XML/Ada.
In all cases, and assuming you installed both static and shared
libraries, you can choose among the two by setting the environment
variable:
LIBRARY_TYPE=static
or:
LIBRARY_TYPE=relocatable
Whatever method you used to build your application, you might have to
change, at least on UNIX systems, the environment variable
*LD_LIBRARY_PATH* so that it contains the "lib/" directory in the
XML/Ada installation, so that the dynamic libraries are correctly
found.
This is not needed if you build XML/Ada as a static library.
7.1. Running on VxWorks
=======================
On VxWorks, XML Ada processing might require more stack space than
what is typically available from the VxWorks shell, the tasks spawned
from there with "sp", or Ada tasks with no or a too small Storage_Size
value attached.
Such stack overflow conditions are typically characterized by non-
deterministic erratic behavior and can be cured by allocating more
stack space for the tasks involved.
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