• Created by Unknown User (chamont), last modified on Jan 13, 2009

Warning

The skimming tool has been generalized and externalized. The information below is obsolete and related to an old release. If possible, use a more recent release and get the corresponding documentation from the new TRAC server.

Requirements

The skimmer is only usable on linux.
At run time, the release v5r0 depends on :

  • Perl 5, which should be found with "/usr/bin/env perl".
  • ROOT 5.10 to 5.18 : the user can specify $ROOTSYS to any ROOT release, and it will be used as is by the skimmer, but the only really validated releases are 5.10/00, 5.14/00g, 5.16/00-gl1 and 5.18/00b.
    At installation time, it also depends on gmake.

Installation

Check out

When one wants a given <release> of the skimmer, he must check out the package "DataServer" with the tag <release> from the GLAST CVS repository. Then he just needs to make "bin/skimmer" a reachable executable. For example, if one stores all the release under a single <SKIMMER_DIR> directory :

prompt> export CVSROOT=:ext:<user>@centaurusa.slac.stanford.edu:/nfs/slac/g/glast/ground/cvs
prompt> cd <SKIMMER_DIR>
prompt> cvs co -r <release> -d <release> DataServer

Compile

The skimmer top routine is a perl script which will execute a set of binaries. Those binaries are depending on ROOT libraries. When installing a new skimmer release, the administrator must compile the source code several times, one for each ROOT release available at the site and supported by the skimmer. Later on, when a user run the skimmer, the top perl routine will look at $ROOTSYS so to know if the user require a specific ROOT release, and it will use the corresponding set of binaries.

Thus, for each ROOT release which is supported by the skimmer (from 5.10 to 5.18) and available on the site, the administrator must :

  1. define $ROOTSYS
  2. move to the skimmer bin directory
  3. run make_skimmer

For the privileged noric cluster, there is a single script "make_skimmer_glast" which is doing this task for all the ROOT releases officially supported by GLAST and the skimmer.

Configure shell environment

At last, the administrator should make the main access routine "bin/skimmer" a reachable executable. For example, if one stores all the release under a single <SKIMMER_DIR> directory, he can add a software link to "bin/skimmer" in one of the standard directiry declared in $PATH, or extend the definition of $PATH in the site setup files :

sh> export PATH=<SKIMMER_DIR>/<release>/bin/skimmer:${PATH}
csh> setenv PATH <SKIMMER_DIR>/<release>/bin/skimmer:${PATH}

Some tips when installing and using the skimmer outside SLAC

If you want to skim a kind of data which is not tuple-like, remember the skimmer will need to load the corresponding libraries (such as libmcRootData.so for mc data). So the site administrator and/or user must ensure those libraries are reachable from the machine where the skimmer will be running, for all the releases which were used when generating the data of interest. If you recompile those libraries locally or copy them from SLAC, you must mimic the directory structure used at SLAC (as expected by the skimmer). Especially, for a given <main_package> and a given <release> (for example GlastRelease and v9r3) the path of the directory containing the libraries should end with "/<main_package>/<main_package>-<release>/lib/" (for the example : /GlastRelease/GlastRelease-v9r3/lib/). The top directories of those libraries should be declared in shell variable SK_LIBRARY_DIRS.

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