Configuration of BES Modules

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Under construction 11/20/14

Use the modules branch of bes to automatically build modules.

Tis pages describes how to take an existing BES module and incorporate it into the modules branch of the BES so that it can build both as a standalone module and as part of an ensemble of modules built using a single configure script and Makefile. The first step is to add the module as a git submodule and then make a handful of edits to the bes and module's configure.ac and Makefile.am files. The changes are minimal and the resulting module code will build both as a standalone module and as part of the 'combined modules' build. The BES will also build as a standalone program, and because of the way git's submodules work, it's easy to checkout just the BES with the baggage of the modules.

1 To add a new handler to the BES repo on github

The following assumes that you have cloned the BES repo from github and are on the master branch.

For each module to be added:

check it out in the bes/modules directory
git submodule add <github repo url>
make a modules branch
cd <module dir>; git branch modules
switch to the new branch
git checkout modules
set the modules branch in the .gitmodules file
emacs .gitmodules; branch = master

Now follow the recipe outlined in the following sections of the page...

2 Changes to the module's Makefile.am

Hack the module's Makefile.am so that CPPFLAGS and LIBADD reference the correct places given that the code will build w/o bes first being installed

if DAP_MODULES
AM_CPPFLAGS = -I$(top_srcdir)/dispatch -I$(top_srcdir)/dap $(DAP_CFLAGS)
LIBADD = $(DAP_SERVER_LIBS) $(DAP_CLIENT_LIBS)
else
AM_CPPFLAGS = $(BES_CPPFLAGS) # or wahtever was set here or in ..._CPPFLAGS
LIBADD = $(BES_DAP_LIBS)      # and ..._LIBADD
endif

then

# comment this out to force use of AM_CPPFLAGS libcsv_module_la_CPPFLAGS = ...
libcsv_module_la_LIBADD = $(LIBADD)

For unit-test code you may need to add some of the bes code to the link line. To do that, use the makefile variables:

  • BES_DISPATCH_LIB
  • BES_XML_CMD_LIB
  • BES_PPT_LIB
  • BES_EXTRA_LIBS

where you almost certainly want to use $BES_DISPATCH_LIB $BES_EXTRA_LIBS

Look for a line like

xml_data_handler.conf: xml_data_handler.conf.in config.status

and add $(top_srcdir)/ in front of config.status

If the module uses besstandalone, add bes.conf.modules.in to the EXTRA_DIST variable in the Makefile.am.

3 Changes to the module's configure.ac

Add "AM_CONDITIONAL([DAP_MODULES], [false])" to the modules configure.ac

If the module uses autotest to run a set of regression tests using besstandalone, add generation of bes.conf from bes.conf.in. You'll also need to make corresponding changes in other places, documented on this page.

4 Additions to the module's files

Add bes.conf.modules.in. The key parts of this file that are different from the existing bes.conf.in are:

BES.modules=dap,cmd,csv
BES.module.dap=@abs_top_builddir@/dap/.libs/libdap_module.so
BES.module.cmd=@abs_top_builddir@/xmlcommand/.libs/libdap_xml_module.so
BES.module.csv=@abs_top_builddir@/modules/csv_handler/.libs/libcsv_module.so
 
BES.Catalog.catalog.RootDirectory=@abs_top_srcdir@/modules/csv_handler
BES.Data.RootDirectory=/dev/null

Note how the BES libraries are referenced (@abs_top_builddir@/dap/.libs/... ...) and how the BES.Catalog.catalog.RootDirectory is specified.

Add a .gitignore

Make sure to add the bes.conf.modules.in file to git.

5 Changes to the BES' configure.ac

Add files to be build by BES' configure:

    AC_CONFIG_FILES([
    ...
    modules/dap-server/Makefile
    modules/dap-server/asciival/Makefile
    modules/dap-server/asciival/unit-tests/Makefile
    modules/dap-server/asciival/unit-tests/test_config.h
    modules/dap-server/www-interface/Makefile
 
    modules/dap-server/bes-testsuite/bes.conf:modules/dap-server/bes-testsuite/bes.conf.modules.in    ...])
 
    AC_CONFIG_FILES([modules/dap-server/www-interface/js2h.pl], [chmod +x modules/dap-server/www-interface/js2h.pl])

using the trusty cut and paste and prefixing them all with modules/<dir name>. Put that in the the AM_COND_IF that's at the configure.ac file. NB: The highlighted line show how to make autoconf use a template with an arbitrary name (bes.conf is made from bes.conf.modules.in instead of bes.conf.in in this case).

If the module uses a m4 macro defined in a file in its conf directory, copy that to the bes/conf dir. You then should add a call to that macro to the bes' configure.ac script mirroring the call in the modules's configure.ac script. If the macro looks for a library, etc., that will possibly/likely be in the hyrax-dependencies bundle, hack the macro so that it takes an extra parameter that is the 'master deps' directory. Look at a macro like the ones for hdf5 or netcdf to see how to do that easily. If the module looks for a library using autoconf calls in line (in configure.ac), just copy those in, hacking as needed. Most of the handler-specific code in configure.ac is grouped toward the end of the script.

6 Changes to the BES' modules/Makefile.am

Given the code is in modules/<dir name>, add <dir name> to the modules/Makefile.am as a subdir.

7 Pushing the new branch to the remote repo

double check the .gitignore file and that you have git add the bes.conf.modules.in file
git status
commit changes to the local repo
git commit -a
push those local changes to the remote repo and set this new branch to be the one the code tracks
git push --set-upstream origin modules
check the bes and commit there
git commit -a
and push those changes (the upstream repo was already set)
git push

8 Git Hacks

To manage an empty dir in git, put a .gitignore file in it that ignores everything except itself:

# Ignore everything in this directory; this hack enables git to track
# and fetch, etc., an otherwise empty directory.
*
# Except this file
!.gitignore