Python makes it easy to write Windows services (via pywin32 extensions). That part is easy. The problems sometimes happen when you try to run them, with a commonly reported error - "The service did not respond to the control...", which is error 1503.

If one runs the service compiled as an exe (via py2exe for example), there are a bunch of issues like the module import paths changing. I haven't had the time to dig really deep into that. But this might strike even if the service is being run uncompiled (from a .py file).

One of the first things to check is whether pythonservice.exe (from the win32 module) executes cleanly - this is the binary responsible for actually loading your service script/module. If pywin32 was installed in the usual way, it should be located at C:\Python26\Lib\site-packages\win32\pythonservice.exe

Running this should give an immediate idea of what's going wrong. It usually turns out to be a "msvcr90.dll" or a "python26.dll" error. (Of course, all this is Python 2.6). When that is running alright, then it's time for some debug fun.

To debug the python service, just run pythonservice.exe with the '-debug' option and the service name as the argument. This attaches the stdout/stderr to the terminal. For example, if the service uses BaseHTTPServer, all the request/response logs will show up.

Graphvizis my newest discovery. I used to meddle with Diaand xfigwhenever I needed to publish any diagrams (network diagrams for example), but they have their problems - one has to worry about the layout and spacing among other things. The content becomes secondary to the layout. That's exactly the reason why I don't use word processors. Systems like Textile, Markdown, reStructured Textand the king of them all, TeXlet you focus on the content and figure out an appropriate layout (some of them with a little help - but the focus still remains on the content).

Graphviz does that for graphs and it's just awesome! Examples speak louder than words, so here they are:

graph g {
        foo -- bar;
        bar -- baz;
        baz -- spam;
        eggs -- spam;
        spam -- bar;
        foo -- spam;

        label="The foo bar graph"
}

graph g {
        foo;
        {rank=same; bar; baz; spam; eggs;}

        foo -- bar;
        bar -- baz;
        baz -- spam;
        eggs -- spam;
        spam -- bar;
        foo -- spam;

        label="The flatter foo bar graph"
}

digraph G {
        foo;
        {rank=same; bar; baz;}
        {rank=same; spam; eggs;}

        foo -> bar;
        bar -> baz [arrowhead=vee];
        baz -> spam [arrowhead=diamond];
        spam -> eggs [label=" an edge " arrowtail=diamond arrowhead=vee color=red];
}

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