Wednesday, October 25, 2006

Designing gadgets and widgets for uploading files to Memba Velodoc

  • A sender, a Receiver, a Subject, a Message, a File to upload and a checkbox to accept terms (see;
  • A progress bar to monitor upload progress;
  • A professional look & feel;
  • To be developed in 3 to 5 days max.
Reference documentation
Findings and impact on technologies
A windows sidebar gadget is a piece of DHTML hosted in the sidebar. Generally what you can do with DHTML can be done in a gadget.

There are limitations though, most of which are related to the browser security sandbox. Effectively a gadget is hosted locally, which has impacts on how it can communicate with remote web sites.

In particular, developing a file upload gadget with a progress bar in DHTML requires a cross-domain iFrame and scripting the iFrame in this case is forbidden. I have tried two nested iFrames which gives you scripting but the deepest iFrame opens in a new browser window instead of within the gadget. The only workaround I have found in half a day is to display the progress bar in a new browser window, but this does not look good and I was not prepared to lose more time.

So, I have considered XBAP WPF browser applications and although there is no File Upload control, I seem to have found the foundations for a file upload gadget here:

But WPF development is really early stage, development environment is primitive, documentation is lacking and I got worried about some warnings related to the sandbox that are mentioned in the literature quoted above.

In these circumstances, the only alternative was Macromedia Flash. I have even found a couple of examples running on the web. I have hosted them within an iFrame of a bespoke gadget and there I was: at the end of day one, I had my design and a fully functional (but ugly) prototype. Further documentation is available at:

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