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A semantic modeling and query language (CQL) and application runtime (the Constellation API)

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ActiveFacts provides a semantic modeling language, the Constellation Query Language (CQL). CQL combines natural language verbalisation and formal logic, producing a formal language that reads like plain English. ActiveFacts converts semantic models from CQL to relational and object models in SQL, Ruby and other languages.

The generated models are guaranteed congruent, which eliminates the object-relational impedance mismatch. Semantic models are much more stable under evolving requirements than either relational or object-oriented models, because they directly express the underlying elementary facts, so are not susceptible to ramifying change in the way those attribute-oriented approaches are.

Semantic modeling is a refinement of fact-based modeling techniques such as ORM2, NIAM and others. ActiveFacts can convert ORM2 files from NORMA to CQL. Fact-based modeling is closely related to relational modeling in the sixth normal form, but doesn't suffer from 6NF inefficiency. The relational models it derives are highly efficient.


afgen --sql/server myfile.cql
afgen --ruby myfile.cql
afgen --cql myfile.orm


  • sudo gem install activefacts


* Queries are parsed, but not yet generated to SQL.

* The Constellation API lacks SQL persistence (but is already useful;
  the CQL compiler uses the generated Ruby code extensively)

* Validation of semantic models is incomplete



Copyright © 2008 Clifford Heath.

This software is provided 'as-is', without any express or implied warranty. In no event will the authors be held liable for any damages arising from the use of this software.

Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.

  2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.

  3. This notice may not be removed or altered from any source distribution.

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