Bill Gibson's Blog : Oslo

Oslo CTP update; Data Modeling Design Patterns in M

Bill Gibson — Thu, 29 Jan 2009 01:59:00 GMT

As modelers, one of the things we're doing all the time is looking for patterns - trying to distinguish what in each model is truly unique to the domain from that which is more broadly applicable, and then either using or adapting existing patterns or harvesting new patterns to put in our back pocket. The January Oslo CTP update (woohoo!!) on the Oslo Dev Center includes an initial set of data modeling design patterns. These patterns, described and illustrated in M, include patterns for modeling enumerations and relationships, including closed type-based enumerations, open extent-based enumerations, and one-to-many, many-to-many and one-to-one relationships.

While this may seem like pretty basic stuff you'll likely find some or all of it useful, particularly if you're new to M and coming at it and repository modeling with an OO rather than relational mindset. The patterns all have code samples so you may find it useful to have the patterns open while you're coding.

We'll add more patterns as our experience grows and the language evolves and is more fully implemented. In the pipeline are patterns for vertical partitioning, including patterns that help when mapping a generalization hierarchy in a conceptual model to a relational design. You can see some early exploration of these kinds of patterns in the domain schemas included in the CTP.

As always, we'd love to get your feedback. If you have any comments on the patterns and the usefulness of this kind of material let us know. And if you have any broadly useful patterns in your back pocket that might map nicely into M they would be great to hear about also.

Domain Modeling

Bill Gibson — Wed, 28 Jan 2009 07:27:00 GMT

My focus within the Olso team is on domain modeling – creating models for specific problem domains using the Oslo modeling platform’s languages and tools. Let me describe why we think of this as more than just data modeling.

At the center of an Oslo domain is a data model authored in M. The primary purpose of this model or schema is to describe repository storage, defined in terms of extents. This domain schema defines data integrity constraints and may also define reusable data definitions or types, as well as computed values that describe interesting ways to retrieve and compute data from the model. The schema is compiled into SQL, resulting in tables, views, constraints and functions which are loaded into a SQL Server database primed with some simple Repository patterns. The result is a simple and easy-to-query and otherwise normal SQL database, which can be queried using any SQL data access API or tools.

Surrounding this data model and considered part of the domain may be any number of domain specific languages, which if developed using Oslo may be textual, authored in MGrammar, or visual, authored with Quadrant. These DSLs define ways in which domain information (instance data) can be created or presented. Any number of textual and visual languages may be defined for the same domain, each customized to provide some specific perspective. A domain can also reference other domains, so models and languages may also reference (and in due course, embed) other models and languages.

Accompanying each DSL may be utilities that map or import/export language 'documents' to and from repository storage. For textual DSLs described in MGrammar simple transformations can be expressed in the grammar itself - more complex transformations need to be described separately. A key Oslo scenario will involve cataloging and potentially creating/editing pre-defined artifacts that might otherwise be created and/or consumed externally by other tools.

Collectively, the domain schema, textual and visual DSLs, and their accompanying import/export tools define what we think of as a domain from an Oslo standpoint and will typically be evolved as a unit. This whole-domain perspective is an important part of the way we think about modeling with Oslo and strongly influences how you can expect the Oslo platform to be developed.

You can see some early examples of domain schemas included with the CTP on the Oslo Dev Center. Take a look if you can.

Next up, data modeling design patterns in M...

Getting Back in the Saddle (although no longer on a Whitehorse)

Bill Gibson — Wed, 28 Jan 2009 05:12:00 GMT

Long time no blog! In the meantime I've changed jobs within Microsoft; I've been working for the last several years on the modeling platform known as “Oslo” which 'came out' at PDC in October. You can find out more about Oslo at the Oslo Dev Center.

I was amazed to find my blog still accessible after being dormant for so long. While it was with some nostalgia that I freshened up the links to the Whitehorse tech notes below, you should follow this link to get the latest on Visual Studio Team System Architect Edition.