Saturday, March 20, 2004

WhiteHorse and Virtualization (take 2)

Alex Torone the Lead Program Manager for the Microsoft Visual Studio Enterprise Tools Team gave me a gentle kick in the balls regarding my inaccurate posting around WhiteHorse. Here are his clarifications:

What the diagram really represents:
The LSAD (Logical Systems Architecture Diagram) represents "logical run time hosting environments" (hence the name). Each box represents a "logical server type". Specifically, the large blue boxes represent a configuration of IIS, whereas the endpoints on the large blue boxes represents web sites. We model the entire IIS meta base (in this example). So a user could either supply "desired configuration" in the tool, or they could simply point to a "canonical server" that has the "desired configuration" and harvest those settings. Once the settings have been defined in the LSAD model, the user can then define constraints against the application environment. For example: Suppose my datacenter policy for "front end web servers" require web apps to use forms authentication and impersonation. These constraints will be validated against the application designer (we model all of system.web for example) and can be expressed in this logical design. There are also two additional layers in the SDM model (part of DSI refer to links below) which represents the network layer, and device layer that are more in line with your comments and are slated for a much later tools and platform release.

About the Physical DataCenter:
Data Centers host many types of applications. Network infrastructure diagrams (we've all seen them) have physical machines, IP address, Vlans, switches, routers, etc. The LSAD is meant to represent abstractions over the physical data center. We want to represent types of server not physical servers. One box on the LSAD does not necessarily equate to a physical server in the data center. In fact, you can create multiple Logical web servers and place then on one physical server with SQL as an example. When we get to actual deployment releases post Whidbey (please refer to the Dynamic Systems Imitative (DSI) links below), we will then provide a logical to physical mapping. This action will populate all of the deployment parameters with they physical URL's of the web server etc.

In conclusion, the LSAD is about conveying that information which is important to the developer (such as what kinds of services are available to me, what communications pathways are open, what configuration must I adhere to, what are the boundary conditions that I must be aware of, etc) such that we will increase the probability that their design will actually work when it is physically deployed.

The more I dig into the DSI, the more impressed I am. If they can pull it off with design-time integration it will be one heck of a story. Here are some links Alex provided me to reduce my ignorance:

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