Inside Technique : Web Annotator : Design Issues/ Download Files

Some Design Shortcomings:
Any output added to the document from ASP code, will be included in the document after our copy of the original. So if the document is dependent on other pages that run from asp, our design does not account for this. Client side script blocks are negated by canceling any events in the document using cancelBubble= true. This will turn off any script support originally included in the document.

Finally, and the biggest flaw by far, is this document is not intended as a real time discussion document. This means, if two users are annotating the same document, one will overwrite the others changes. You can change this behavior by modifying the code to check for a last modified time and date. If you find the document was edited by someone else, you can either try to take any changes to the document still open, and merge them into the document that was just saved or create a new file.

This obviously requires considerably more effort and code and will be the subject of a follow up article using xml to store users, comments and timestamps.

What's left:

We now have prototype that allows users to add comments to a web page and save it back to the server. Several of the techniques discussed could have been handled using different approaches to get the same results.

With the coming of age of XML many features can be added to support real-time collaboration solutions. In a follow up to this  article, we'll revisit this application and add new features that allow for two users to share the same document at the same time without overwriting the others changes.

Hopefully this has opened up some new doors and new opportunities for you. A few scenarios you could develop from this are an web based html editor, a custom file creation tool that lets users copy and paste html from other documents into the annotated one or a discussion page that can pull connected users from an xml file and load the latest changes into the document.

Sample Files
You can download the sample files and article. Included are all the scripts and a read-me on how to setup your server.

happy coding..
Kenneth Cox

Additional References:

http://www.wrox.com/
Titles:  XML Design and Implentation (Paul Spencer)

http://www.insidedhtml.com
Titles: Inside Dynamic HTML (Scott Isaacs)

http://msdn.microsoft.com/xml
Titles: XML in Action (MS Press Books)

About the author:
Ken works as a senior web developer for Pacific Life Insurance in Newport Beach Ca. His focus is on thin client application design using Microsoft tools and technologies for the web. When he's not working, he can be found cursing his old code. You can reach him at codenut@hotmail.com

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