Datasheet

Part I ✦ An Introduction to UML

development. Each profile provides customized modeling elements that map to the

common elements and features in each of these architectures. This approach

enables the modeler to focus time and energy on the project content instead of the

unique modeling features of the implementation domain.

The standardized architecture of UML is based on the Meta-Object Facility (MOF).

The MOF defines the foundation for creating modeling languages used for object

modeling, such as UML, and for data modeling, such as the Common Warehouse

Model (CWM). The MOF defines standard formats for the key elements of a model

so that they can be stored in a common repository and exchanged between model-

ing tools and languages. XML Metadata Interchange (XMI) provides the mechanism

to implement the sharing of these modeling elements between modeling tool ven-

dors and between repositories. This means, for example, that a project can use one

tool for developing a platform-independent model (PIM) using UML diagrams and

switch to another tool to refine the model into a platform-specific model (PSM)

using a CWM model to generate the database schemas. This standards-based

approach places the choice of tools in the hands of the modelers instead of the

tool vendors.

UML models can be precise enough to generate code or even the entire application.

Automated test suites can verify the accuracy of the model. When coupled with

tools to compile the UML model, the model can even be executed before any code

exists. Vendors (for example, Kabira Technologies

www.kabira.com and Project

Technology, Inc.

www.projtech.com) are already providing compilers that are

being used in projects today. A fully executable UML model may be deployed to

multiple platforms that each use different technologies. A model might be deployed

in one place using one language, middleware, and database configuration, and at

another location with an entirely different configuration. The mapping of the model

to an implementation configuration is accomplished using a profile, with a separate

layer that maps the two requirements, the model and the implementation environ-

ment. To use the model in other implementation environments, simply create a new

profile. Thus the UML profile represents a level of indirection between the model

and the implementation environment, freeing each to be created independently of

the other.

All of these features didn’t appear overnight. A great deal of collaborative effort

was invested to create the current standard, and not without conflict. You may have

already heard people taking sides on a variety of modeling issues and practices

that arise when they try to use UML. To clarify some of the reasons behind these

debates, I begin with a brief history explaining how UML first came to be. If you can

understand the process behind the ongoing development of the standard, you will

be better equipped to follow the changes between version 1.4 and the new develop-

ments in version 2.0 described throughout the rest of this book. Even more impor-

tant, you need to understand how UML fits into the much larger plan by the Object

Management Group (OMG) to standardize systems development with Model-Driven

Architecture (MDA).

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