Python virtual environment
Hosting multiple Django projects requires to keep deployment and libraries in control. Imagine, that an one year old Django application is written for Django 0.96, but new projects are written using the actual version 1.1.1. It is possible, of course, to rewrite the old applications to be compatible with the actual version, but rewriting many projects might consume a lot of time.
There is a smart solution to deploy applications using different versions of Django on only one production server. This can be done easily using the "virtualenv" library, which allows you to create unlimited number of python environments including the site-packages directory.
At first, install the virtualenv library with easy_install:
-
easy_install virtualenv
Then, create a new Python virtual environment:
-
virtualenv --no-site-packages /usr/local/lib/my_new_python_environment
The --no-site-packages parameter avoids access to the global site-packages dir to the virtual environment. Finally, activate the new python environment with command:
-
source /usr/local/lib/my_new_python_environment/bin/activate
Deactivation of the activated environment is done by following command:
-
deactivate
Detailed how-to on deploying Django project using the new virtual environment through mod_wsgi is available at http://jmoiron.net/blog/deploying-django-mod-wsgi-virtualenv/
Apache as proxy for IIS 7
Believe or not, a large scale AJAX application running on IIS 7 caused fragmentation issues at transport layer causing "connection timeout" error on the client side. An AJAX HTTP request passed to the IIS, which generated a proper response. The response was split to insufficient number of frames in the Windows net core: several frames were sent to client, but several frames were never send (and probably never generated).
The only practicable fix was to use Apache web server as proxy between the client and the IIS. There were no fragmentation issues and no timeout errors on the client side since applying and texting the proxy fix.
Apache rocks.
Business process models with open-source tools and standards
Business processes are often described by workflow, which means a sequence of operations declared as work of a person, a group of people, an organization or staff, one or more simple or complex mechanisms [1]. From the analyst point of view, suitable visualisation is often needed for analysing, projection or presentation of workflow sequences. Programmer of workflow sequence needs an effective process notation in form of source code.
There are the XPDL notation standard (XML Process Definition Language) [2] and several tools, which supports this standard fulfilling all the needs mentioned above. Please follow references at the bottom for details on XPDL standard. Let's look on several XPDL tools:
- Enhydra JaWE: an open source visual editor for workflow processes definition written in Java. I have been successfully using this editor for enterprise processes analysis. This tool is available as paid "professional edition" which contains a lot of additional features.
- JPEd: a next one open source editor based on previous editor's source code. This editor offers basically quite the same functionality as Endydra plus some useful features in addition, e.g. PDF reports, plug-in interface and SVG graph outputs.
I will appreciate comments with your own experiences and tools used for business process modeling.
References:
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