Brad Lucas

Programming, Clojure and other interests

Bad Markup Causing Multiple Calls To Spring Controller

January 10, 2007

Had an interesting problem come up with a client using Spring MVC. For some reason they where experiencing GET requests to a Controller resulting in two calls to the Controller. It was as if the browser was making to requests for each user initiated request. Of course, implementing a simple version of the controller and a basic view did not reproduce the problem. Going back to the application and logging continued to verify that the handleRequestInternal was in fact being entered twice.

Nest, the Controller and it’s View where slimmed down a bit to localize the problem. A single test url was setup to point to this controller. Then iteratively parts where changed. Any unnecessary processing was removed so the Controller was excercised from a link and simply returned the View. This still showed the problem. Next, the view was replaced with a very minimal Jsp. When this happened the problem went away. Could something in the existing View cause the Controller to be called again? This didn’t seem likely but it certainly seemed to be true.

Returning to the original view, and selectivly removing one section at at time until the problem went away eventually localized the offending part of the View.

Inside the HTML tag for a TABLE where was a background=”#C3D9FF”. This invalid attribute looked to cause the browser to recall the page as it expected the background to be associated with the BODY.

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Ornette Coleman – Video On Youtube.Com

November 2, 2006

The latest JazzTimes cover story on Ornette Coleman mentions a video on of Ornette on Saturday Night Live back in 1979.

Here is the link.

Ornette Coleman 1979 – SNL

For JazzTimes see Jazz Times – November 2006

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Lispbox – Access Denied – Use Winzip To Extract

November 2, 2006

In setting up Lispbox on a Windows machine I found it wouldn’t run. From a command prompt, running lispbox.bat, returned “Access is denied”.

I discovered that the Security settings on the EXEs were set to not allow them to run.

I realized that I had unzipped the downloaded zip with the unzip included in Cygwin.

After unzipping the Lispbox download with a copy of WinZip the problem went away.

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Errors Install Ruby On Rails On Linux

August 18, 2006

If you see errors like the following while installing Ruby and Rails

custom_require.rb:21:in `require__': No such file to load -- zlib (LoadError)

See the following links as I found them helpful.


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Building Emacs On Linux

August 2, 2006

This is worth repeating if someone needs this tip and finds it earlier than I did.

When building on some versions of Linux, Emacs will seg fault during the build. It is mentioned in the etc/PROBLEMS but was unclear. Eric Raymond posted a cleaned up PROBLEMS file that makes it more clear. (His post is here ).

In short I entered the following and Emacs built fine.

setarch i386 ./configure
setarch i386 make

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