[Clas_offline] CLASWEB Migration Status -- Progress on Pezca... Ready to switch?

[Marty Wise]

All,

 

Using the Pezca-0.4 source package, I was able to build and install it into
our central /apps version of perl without having to build or make any parts
of the EPICS distribution available to it. At runtime, the package still
needs access to a couple of EPICS shared libraries, but this is easily
arranged through LD_LIBRARY_PATH. The bottom line is that I have a working
example of this new configuration.  If you access the URL:
http://claswebnew.jlab.org/cgi-bin/HALL_ABC/top_frame-MEW.pl, you'll see an
example of the configuration at work. This page is a _slighlty_ modified
version of the original --
http://claswebnew.jlab.org/cgi-bin/HALL_ABC/top_frame.pl which does not
work.

 

After building Pezca into /apps Perl, I made a small modification to the
top_frame-MEW.pl script mentioned above. All I had to do was comment out the
line: 

 

    #use lib
('/group/clas/www/clasweb/htbin/PERL_CPAN/lib/site_perl/5.6.0/i686-linux');

 

This change removes the explicit reference to the perl library installation
down in /group/clas/www/clasweb/. Since the script uses /apps/bin/perl, it
Is able to find the Pezca module in the apps build.

 

To address the runtime dependence on the epics shlibs, I set LD_LIBRARY_PATH
in the web server configuration to include a temporary directory into which
I've placed the libca, libCom and libezca shared libraries.

 

This seems to work, though it's hard to be sure since I'm not very familiar
with them.

 

The problem is that with the explicit library reference, there is no way to
fix this without modifying all the scripts individually. You guys have a
number of scripts configured like this. Changing them now will break them on
the running clasweb. I can easily find and fix most of these problems, but,
I will need to do it as part of the cutover.

 

So. given these results, if nobody sees any problem with these changes, can
we plan to do the switch to the new server today? I will need to have both
the new and old servers offline for an hour or two to make all the necessary
changes. Then, there will certainly still be other problems that turn up
afterward. These will need to be dealt with as they are discovered. I think,
however, that all the major stuff that has been seen has been addressed.

 

I should also point out that reverting back to the original server in the
event of insurmountable problems of some kind will require a similar 1-2
hour outage to switch back. Personally, I hate to go back in general, and in
this case, RHEL3 (on the current clasweb) is obsolete and no longer
supported, and has been holding up a number of projects you guys have asked
for that require newer software versions - e.g. newer MediaWiki, MantisBT,
DocDB, etc.

 

So, can I move forward with the switch? If so, when is a good time?

 

Marty

 

 

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