Just thinking out loud, but I thought someone might give me some ideas how to approach a solution for a part time gig that I can't seem to make go away. :-)

What I've got is one of those web page applications that runs via user sessions. The data being viewed is similar to project management wherein users interact with the system to view and modify the state of their projects. The managers build a tree of projects that allow them to keep tabs on the state of various projects throughout the company. Not really supposed to be a complex project management system - that gets way too involved and becomes more work than it's worth - this one is very simple on purpose so that it might actually get used.

The application works fine. Problem is, though, that I have users that want to be able take the data offline and then upload changes back onto the main server after modifying it locally. Needless to say, a web application works exclusively with thin clients (i.e. browsers) and a web server. Means I basically need to write a parallel program that retrieves the data on attachment and saves off any changes. Synchronization can be a complex issue, in that you may have two users modifying the same data offline at the same time, which means you have to do merges and what not (or one may modify it and the other delete it).

Anyhow, I was wondering if anyone else had written any sort of web application where you had to support offline stuff? Kind of stuck trying to figure out the best way to do this. My inclination is to write a totally seperate program that has it's own user interface and only talks to the web server during the synchronization process. Probably be inclined to use Python and it's GUI libraries for the user interface. But I never like the idea of having duplicate code that achieves the same end. The web code doesn't appear to be reusable in this sort of framework - the clients in question don't have local webservers, so it's like two completely different programs with the same purpose.

The only other thought I had was using javascript in the browser to draw the pages on the client and have them read and write the data on the local drive. That is, still use the browser as the sole interface but have the webserver software embedded within the pages - instead of retrieving the info from the server the actions would be a function of javascript code embedded within the pages. But that seems to get complex as well.

Thanks.

Thanks for input.

It takes more storage space to do this, but it can save your bacon when two employees update the same record and you need to roll back to an older version.

For the most part, synchronization is more a theoretical problem, since most of the data entry for the nodes are the responsibility of a single person. I should probably mention, that the server software is also touching the data on a nightly basis, so the issue is not just two users stepping on each others toes, but also the system modifying the entries as well.

I don't think folding the entries on top of each other will be too bad. The app is designed to keep track of history, so that all entries are non-destructive. The only thing the synchronization really has to decide is what fields to merge within the records and which one comes out on as the latest entry when the same fields are changed.

Client side VBScript/Javascript using ADO should work fine on an Access database or some file that is stored on the user's hard drive.

Although I could try to push an MS only solution, I've been trying to avoid that scenario. Problem is that I don't really want to deal with the end users in any significant fashion. These users are not internal as the customers are from a number of different companies. My experience has been that once you start installing MS apps, you then have to take on significant customer support. The whole reason for writing a thin client in the first place was to keep my exposure to client problems to a minimum.

But since I am free of that Microsoft Shop, I'd most likely use Java and JDBC or something.

The main problem I have with Java is that I don't particularly like AWT or Swing. For importing and exporting the data, it would be a nice environment. But the problem I'm having is that I'm not sure how to build the user interface for the forms that I'm using in the web app.

There are some really stripped down http servers written in Java that might be able to do the trick. Don't know if I want to install much that has a significant footprint. Then again, I don't enjoy the prospect of supporting my own web server either. Will have to look into how big a chore it is to get a minimal webserver that can handle form generation and submissions.