h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

What should developers do to use the Windows DNA architecture & services?

The Windows DNA CD ROM said:
"First, they should partition their application into three logical tiers:
Presentation, Business logic and Data.
For Presentation, they can choose the appropriate Windows-based components and technologies to provide broad client reach and the richest possible interface.

For Business logic, developers should write COM components that use the rich application services of the Windows NT® operating system.

For Data, developers can use ADO to access data, OLE DB to expose data, and XML for interoperability and data representation. "

Yes, Bob,

Application design in a tiered approach is not only better, but just about necessary for a large application, else, the bulk of the program becomes an unintelligible monolith of code with no easily found divisions.

The tiers don't have to be any particular methodology or regimentation, but the typical seperation is at the data storeage for the back end tier, a business object of compiled ActiveX DLLs to do everything the application is designed to do, and a user interface tier, that could be a web browser, or an application that displayed information from the middle tier, and invoked actions and services offered by the middle tier.

Think of the middle tier as a program without an interface. The first tier as an interface without a program, and the third tier backend as where any data lives when the program isn't running.

There's nothing that casts this in stone, either.

The Microsoft perspective on the DNA (Distributed iNternet Application) paradigm uses an administrative layer to set availability to middle tier components through admistrative services of the Internet Information Server.

Without owning and administrating an internet/intrAnet (MS IIS) server, and being able to place middle tier components there to be served to the Web public with access rights, then the DNA approach is stopped short.

The DNA approach will eventually assimilate all of the MS development platforms. For instance, VB 7 is planned to have a project type that will compile directly to an MS IIS server, provided one is available that will accept the program.

Some thoughts.

Cheers,
DonEMitchell

You have pointed out that
'we need to tier the development but that nothing is cast in stone...'

I think my point here was that we need to set down some sort of agreed structure between us so that when we start to create the components that make up the products we will be creating together, they will work sensibly together... then I was suggesting that the Microsoft DNA model provided as good a structure as any ... and from my reply to the 'shared mission' message earlier I hope we are talking on the same wavelength when I suggest that we work towards web components for each of our products? .. do you foresee any difficulties with implementing our products in this way?

It seems to me that once we have the right structure of topic discussions for product development projects on this website, we can start to develop the relevant components for incorporatin into the agreed structure, feeding into the agreed XML formats, and hopefully this will reduce any 'compatibility' issues later on down the development road if the components need to work together to perform the overall service that we had envisaged from our webserver (wherever that will be !).