=======================
Tuesday, April 28, 2015
=======================

Continued to search the reason of :ticket:`150` (public web interface
for lino_noi).

Fixed one of the side effects announced yesterday: icons were not
properly displayed since their URLs have changed.


Uugh! Leif Azzopardi and David Maxwell write about software
patents. After explaining how "Netscape programmer Lou Montulli took
the concept of a magic cookie and applied it to web communications.",
they add "Of course, with such a great idea came a software patent -
and you can read `US patent 5774670
<http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=5774670.PN.&OS=PN/5774670&RS=PN/5774670>`_
that was submitted by Montulli himself."  No, it is not "of course" at
all. The greatest ideas in history of mankind are *not* patented.


I noticed that my local :xfile:`djangosite_local.py` had been setting
:setting:`SESSION_COOKIE_PATH` when
:attr:`lino.core.site.Site.site_prefix` was something else than the
default. Since this trick seems a general need when hosting several
Django projects under the same hostname, I added it to 
:meth:`lino.core.site.Site.init_before_local`.

In a stackoverflow thread titled `Django (Python) problem with
sessionid
<https://stackoverflow.com/questions/4555956/django-python-problem-with-sessionid>`_,
Chris2048 wrote "I had a similar problem, and I fixed it by setting
SESSION_COOKIE_NAME to something other than the default 'sessionid'. I
think google analytics might have been clobbering the cookie somehow."

I don't use any google analytics (AFAIK), but it seems that modifying
the :setting:`SESSION_COOKIE_NAME` from its default `sessionid` to
`ssid` solved the problem.

Then finally, Pindi Albert's story in `Migrating to cross-domain
cookies in Django
<http://www.pindi.us/blog/migrating-cross-domain-cookies-django>`_
helped me to understand the reason for the problem on :ticket:`150`
which took me several days:

After changing the content of :setting:`SESSION_COOKIE_PATH`, my
browser had two cookies for host `127.0.0.1`, both called `sessionid`,
one with path ``/`` and the other with path ``/admin``.  And it seems
that Django *writes* to the cookie with path ``/admin``, but the
browser answers always with the "top-level" cookie, i.e. the old one
with path ``/``.

Now another question is how to avoid this problem in the future?

Answer: stop to misuse the `site_prefix` attribute for specifing that the
"Lino admin interface" is not at root.

I released to :ref:`lf` because everything seemed to work.  But there
is obviously yet another problem ("SITE.kernel is None") which occurs
only in a multi-threaded environment. So I reverted to a (hopefully)
good version::
 
  git rev-list -n1 --before=2015-04-25 master | xargs git checkout

The output of above command is somewhat strange::

    Note: checking out '1ca11541fdcb9da85e1331e2de237c38c28860dd'.

    You are in 'detached HEAD' state. You can look around, make experimental
    changes and commit them, and you can discard any commits you make in this
    state without impacting any branches by performing another checkout.

    If you want to create a new branch to retain commits you create, you may
    do so (now or later) by using -b with the checkout command again. Example:

      git checkout -b new_branch_name

    HEAD is now at 1ca1154... http://luc.lino-framework.org/blog/2015/0424.html

TODO:

- Fix the "SITE.kernel is None" problem
- Change Apache configurations so that it serves the static files. I
  hope that I can serve all static files from one place.