The overall discussion is from an IT Architecture perspective, and does not address the integration issues of Enterprise Architecture Modeling in general.
An IT Architecture model is not simply one single model, rather it is made up of many specialized models that address different phases, requirements, capabilities, systems and deployments.
Premise:
A single IT Architecture Repository will provide a consistent view of the IT Architecture across all aspects of the enterprise. The repository is constructed with a rigorous methodology using a well defined set of conceptual elements and built using a common set of patterns The assets in the repository are described with a comprehensive set of meta data that provides access and reuse. It contains:
- references to enterprise documents
- references to external documents
- models from many sources transformed into the canonical form in the repository
- artifacts built with many tools and techniques either directly stored in the repository or transformed into desired form
In this paper, this overarching Architecture Model is called the Objective Architecture Model.
Technical Barriers
In general, many participants in the Objective Architecture Model creation workflow use a variety of tools from different vendors using different techniques to represent a model. Some simply draw diagrams, some use spreadsheets, some use modeling tools based on various modeling languages such as IDEFx or UML.
There are three broad parts to the problem:
- Common representation of the Objective Architecture Models
- Transforming various source models to and from the common representation.
- A repository capable of supporting extensive management, access, query and governance
Common Representation
Currently, there are several broad standards that specify modeling languages, e.g., IDEFx, UML. The DoD and MOD have defined a set of reports that are meant to provide a basis of comparison of various architectures, and the CADM was intended to define a schema for a repository of all DoD architectures. TOGAF is another standard that broadly defines a methodology for constructing models.
However, there is no standard process or methodology to guide modelers so that they produce models that can actually be compared. Furthermore, there are many tools used to construct the Objective Architecture Models, not all of which are actually models, rather many are simply pictures. Modelers have freedom to construct their models in any way they see fit.
Interchange/Transform
There is no industry-standard modeling interchange solution available for the existing problem. A model exchange standard (XMI) exists for UML, but it does not apply to other notations such as IDEFx that are in use for architectural modeling. Even if UML were the sole notation for the Objective Architecture Model, XMI model interchange would be hampered by the fact that even within the UML tool community both the UML standard and the XMI export and import are incompletely implemented.
In practice exchanging models between tools via XMI is difficult for a number of reasons:
- Different versions of the XMI exist (1.0, 1.1, 1.2, 2.0, 2.1). Tools often support only a few of them.
- Some tools use proprietary extensions of the UML meta-model, or the XMI exporter generates XML code that is not fully compliant with the standards. In either case, the XMI file will not be understood by other tools.
This is especially true for diagram layout information – diagrams are lost in the process.
However, interchanging models is not sufficient to solve the problems facing the enterprise programs. To compare, align and evaluate Architecture Models from various sources, the enterprise must have a common modeling language, and a specific framework and process that specify how to construct a well formed model – i.e., a methodology.
Then there are two scenarios that can be used:
- Create Objective Architecture Models using the “native” modeling methodology and tools
- Import and export models from various sources to and from the Objective Architecture Model
Of course all of these must be governed by version control so that any configurations compiled from these various models and model fragments can be synchronized at the version level.
Next: "Part 4 – Solution Scope" …