Dear TAs,

Here are some things you may want to watch out for in lab:

- They MUST upload to webster to even attempt to test their code.  It won't work if they test from their local machine, because of the browser's security restrictions on Ajax.  If they try from the local machine, it'll either do nothing or else Firebug will barf out a strange red security error message.

- They should fetch the ajax data using a URL of "/urban.php".  Note the leading slash; it's very important because the student's code will be in the /username/lab5/whatever/ directory, but the web service they're connecting to is in the root of webster.  You may want to point this out to them at the start of lab.

- If the request fails, such as from an invalid URL, they may not get very good feedback about what went wrong.  This can be frustrating.  Try having them attach a handler to the onFailure event of the Ajax.Request, as is shown on one of the later Ajax slides.

- Other potential common bugs: Remember that <node>.getElementsByTagName() returns an array, so they need to access that array's elements in a loop or grab element [0] or something like that.

Have fun!


Marty