Last week's newsletter re-visiting the Identity Bus contrasting virtual data storage with persistent data storage brought forth a number of comments on the Network World Web site, which I’d like to address today.

Neil Macehiter suggests that any change to the query would require that, previously, the new query had been anticipated so that the proper database setup could occur: “e.g. to also store the department information with the purchase order. This could, depending on the business logic, require additional update logic e.g. what happens if an employee changes department.” Well, no. While I didn’t state it expressly, all SQL database data is left in the SQL database, with the power of it’s join engine at our beck and call to select only that data which is needed for our particular problem. In compute-intensive environments it might be necessary to devote a computer to servicing these join requests in tandem with the virtual directory server, but that’s a time-honored (well, 10-15 years, perhaps) method of solving compute problems. The various services could even be linked through a separate backbone, or mesh, network to improve throughput both for those services as well as for all of the clients.

It isn’t a question of what work needs to be done – we mostly agree on that. The question is where should the work be done – redundantly at every client, or as a service available to all.

Daniel Halber also suggests that changing the query shows the need for more intense local computing: “I would propose another query: ‘What purchases of computers were made by employees who are below Director level?’ He suggests that my hierarchical method of looking at employee number won’t work with position identifiers. And, of course, he’s right. But that doesn’t change my response as outlined above – a service based approach, rather than local persistent cache – is the more efficient way to do this.

The method I suggested of identifying employees who were hired in the past two years was also called into question. That presented issues which need a fuller discussion, so I’ll get to that in the next issue. But keep those cards and letters coming!

Also, in corresponding with Courion’s Chris Sullivan about the de-provisioning issue I mentioned in the last newsletter we touched on the education market and how it deals with rapid turnover of student accounts. I’d like to hear from folks in the community about how you deal with the de-provisioning issue for: a) graduating students; b) dropouts; c) transfers; etc. We’ll take up that issue soon.

Dave Kearns is a consultant and editor of IdM, the Journal of Identity Management.