COMMON WAREHOUSE METAMODEL SERIES: INFO

Other sources of industry information on the CWM standard

The OMG Web Site

The definitive source of information on the CWM specification, of course, is the OMG Web site itself. The OMG's home page contains links to all of the major OMG interoperability standards (CORBA, UML, MDA, and CWM), plus schedules and registration information for upcoming OMG Technical Conferences, Workshops, and Seminars. CWM-specific information can be found on the OMG's Data Warehousing, CWM, and MOF resource page.

The CWM Web Site

The XML Cover Pages

Other Interoperability Standards Related to CWM

OMG Model-Driven Architecture

The Object Management Group's Model-Driven Architecture (MDA) initiative is an approach to system-specification and interoperability based on the use of formal models. In MDA, platform-independent models (PIMs) are initially expressed in a platform-independent modeling language, such as UML. The platform-independent model is subsequently translated to a platform-specific model (PSM) by mapping the PIM to some implementation language or platform (e.g., Java) using formal rules.

At the core of the MDA concept are a number of important OMG standards: The Unified Modeling Language (UML), Meta Object Facility (MOF), XML Meta data Interchange (XMI), and the Common Warehouse Metamodel (CWM). These standards define the core infrastructure of the MDA, and have greatly contributed to the current state-of-the-art of systems modeling.

As an OMG process, the MDA represents a major evolutionary step in the way the OMG defines interoperability standards. For a very long time, interoperability had been based largely on CORBA standards and services. Heterogeneous software systems inter-operate at the level of standard component interfaces. The MDA process, on the other hand, places formal system models at the core of the interoperability solution. What is most significant about this approach is the independence of the system specification from the implementation technology or platform. The system definition exists independently of any implementation model and has formal mappings to many possible platform infrastructures (e.g., Java, XML, SOAP).

Several of the "Common Warehouse Metamodel" co-authors have written about MDA:

John Poole's MDA paper provides a survey of the MDA's core standards (including CWM), how these standards are currently being realized within the Java Community Process (see below), and their relationship to the disciplines of meta data and adaptive-object models.

Dan Chang presented the following seminar on CWM and MDA at a recent OMG's UML Forum in Tokyo. The presentation focuses on CWM as an example of a Model-Driven Architecture, and emphasizes how CWM leverages the key MDA infrastructure technologies (UML, MOF, and XMI) in providing support for advanced modeling and deployment strategies, including modularity, meta data re-use, and automated generation capabilities.

Doug Tolbert's CWM paper and presentation, presented at a recent Software Architecture Workshop at the University of California, Irvine, provides a very thorough and detailed treatment of CWM as a model-driven approach to data warehouse modeling and integration based on the interchange of shared meta data. This paper gives a very clear, technical picture of the nature of meta data integration issues and how CWM resolves them.

The OMG is currently offering an MDA Seminar Series Webcast. Click on this link for a registration template and schedule.

Java Community Process

The core standards of the OMG's MDA: UML, MOF, XMI, and CWM, form the basis for building coherent schemes for authoring, publishing, and managing meta data within a Model-Driven Architecture. There is also a complementary trend growing within the industry in which these various MDA technologies are being realized in the Java programming language, through the open Java Community Process (JCP). As an implementation strategy (a "PIM-to-PSM mapping" in MDA terminology), this approach ensures that both development and integration are greatly facilitated through the common platform services and programming models (interfaces or APIs) provided as part of the Java language and various Java Platforms.

Current efforts in the Java Community Process aimed at providing Java realizations of OMG MDA and CWM standards are:

JSR-40, or Java Meta data Interface (JMI), provides a formal mapping of the OMG's MOF to the Java language. A JMI implementation allows for the generation of pure Java interfaces for programmatic and XMI-based access to repository-based MOF metamodels and their instances (such as a CWM-based repository). This means that a Java implementation of any MOF-based meta data service can expose both the generic and metamodel-specific interfaces derived from the MOF's interface mapping rules. Java clients have completely portable access to meta data services via JMI. The development of JMI is being led by Unisys and includes the participation of Sun Microsystems, Hyperion, IBM, Oracle, and a number of other industry leaders.

JSR-69, or Java OLAP Interface (JOLAP), is a pure Java API for OLAP servers and applications deployed in the J2EE environment. The development of JOLAP is being led by Hyperion Solutions Corporation, and includes the participation of IBM, Oracle, Unisys, Sun Microsystems, and other industry leaders. JOLAP uses the CWM OLAP metamodel to describe OLAP meta data, thus ensuring that JOLAP-compliant resources are capable of providing completely vendor-neutral representations of OLAP meta data that are fully aligned with CWM. JOLAP also defines query interfaces that support the formation and execution of OLAP queries, along with the management and manipulation of multidimensional result sets. JOLAP also leverages the JSR-40 Java Meta data Interface (JMI) specification as the basis for the automated generation of its OLAP meta data interfaces and in support of the advanced meta data functionality provided by the OMG MOF.

JSR-73, or Java Data Mining (JDM), is a pure Java API for business intelligence applications employing data mining techniques for knowledge discovery and analysis. JDM is similar to JOLAP in the sense that it represents the Java realization of the CWM Data Mining metamodel (whereas JOLAP implements the CWM OLAP metamodel). In particular, the JDM effort has contributed greatly to the development of the newly revised CWM Data Mining model proposed for inclusion in CWM Version 1.1. The development of JDM is being led by Oracle and includes the participation of Hyperion, IBM, Sun Microsystems, and others.

CWM Meta Data Interchange Patterns and CWM Web Services RFPs

The Meta Data Interchange Patterns (CWM MIP) effort is aimed at defining a standard model for formally codifying the structural aspects of meta data content that is commonly interchanged in data warehousing and business analysis scenarios. This greatly enhances overall interoperability because meta data content can unambiguosly identified as belonging to a well-known "pattern". In many ways, the objectives of this RFP are to provide the meta data community with the same benefits that the Software Patterns movement had provided to the object-oriented software development community. Click on the following links to obtain copies of the CWM MIP Revised Submission and Report.

On the other hand, the objective of the CWM Web Service RFP is to build upon the CWM Meta Data Interchange Patterns effort in order to establish an industry standard specification for CWM Web-based services. A complete specification of the syntax and semantics of standard CWM meta data interchange (request-response) protocols, based on typical CWM meta data interchange patterns, is to be developed. As well, a complete specification of the syntax and semantics of a CWM Web services API that allows for loosely-coupled interchange of CWM meta data is also a delivery of this effort. Click on the following link to view the CWM Web Services RFP.