The Comsys-TIM Transformation stage reduces the time it takes to specify replacement applications while improving the integrity of resulting designs and implementable systems. Transformation augments top-down design and analysis techniques by providing analysts with information about legacy systems and, optionally, making that information available for reuse under the target architecture.
This is accomplished by applying various analysis and reverse engineering techniques to understand how current systems work and, if applicable, reusing designs or components from those systems in the creation of new systems.
Formal models are created through the use of top-down / bottom-up analysis of current and target applications. Top-down models are derived from strategic business planning efforts that are typically driven by traditional development methods. Comsys-TIM captures and integrates bottom-up analysis with these models as a means of expediting the development process and increasing the integrity of the end result. The latter of these benefits is accomplished by verifying that critical data and business functionality is not lost during a replacement / redevelopment effort.
Objectives and Benefits
The role of Transformation is to augment traditional development efforts by reducing the risk of incorrectly re-specifying critical (existing) processes, decreasing development time frames and/or reducing overall redevelopment costs. Specific benefits include:
Development Methodology Interface
When organizations decide to replace one or more applications, they must select a target architecture under which to define those systems. Information architectures are comprised of various categories that include, but are not limited to, the business or functional architecture, data architecture and technical architecture.
At varying levels of detail, models assist with defining a system under an architectural target. Because Transformation supports migration to a new architecture, a target paradigm must be defined for Comsys-TIM mapping purposes.
Logical representations map to various analysis and design models that many organizations tend to use during systems development. One Transformation path supports Information Engineering (IE) and includes process hierarchy/dependency analysis, data modeling, action diagramming and related IE paradigms.
A second path supports object, event and business rule derivation. This second path provides a migration path for organizations wishing to move into an object based, event driven environment. The models mapped to the path in Transformation were selected from the Martin/Odell object oriented methodology. Subsets of these paths may be selectively applied based on an organization's development paradigm.
Comsys-TIM does not describe the process of deriving top-down representations, since this is best done using forward engineering methods. Comsys-TIM does, however, capture and represent existing data and functions in target model representations and, therefore, supports augmentation of these top-down models using bottom-up views.
Finally, if top-down models are not available, a "bottom-up only" approach may be applied to migrate current systems into target environments. While this is certainly an expeditious approach, it introduces a risk of not reflecting strategic architecture requirements in the target system design. Individual scenarios assist in navigating Comsys-TIM via a top-down / bottom-up versus a bottom-up only approach.
Note that planning-level mapping, not addressed under Transformation, is completed as part of the Inventory/Analysis functional assessment process. Again, a formal development methodology is strongly recommended for application replacement targeting a formal target architecture. The diagram on the following page depicts a mapping strategy when using an Information Engineering target architecture.
Transformation -- Task Summary
The Transformation stage is a collection of model-driven techniques. The tasks applied depend on the scenario driving the project and development methodology defining the target information architecture. Each task is similar in that information is captured from existing systems to develop a bottom-up version of a given model. This bottom-up view is then, optionally, compared and/or integrated with a top-down version of the same model type.
This process continues across a wide range of data, process and technology models until enough detail is created to serve as a basis for a new application. The bottom-up analysis component of each task is a required step and serves as formal documentation for existing systems.
This recovery step is typically a combination of manual analysis and tool assisted activity. The mix varies depending on what is being captured. The following major tasks currently make up the Transformation stage.
Practical Suggestions and Guidelines
Transformation's focus is to perform bottom up analysis on current systems and integrate the results of that analysis with top down models. Transformation applies reverse engineering tools and techniques to the problem of understanding how current systems work and, if applicable, reusing designs or components from those systems in the creation of new systems. Understanding and reuse are the two main uses of Transformation.
The first category, application understanding, can be considered as the re-documentation of existing systems using formal representation. Re-documentation may take many forms. Comsys-TIM selected IE models as one medium because these models are in fairly common use.
The task of gathering this data can be made generic for purposes of generating custom documentation for specific installations. Since re-documentation can be useful under numerous situations, one should refer to the Re-documentation scenario of Comsys-TIM for more information on this topic.
Derivation and reuse of existing application designs or components, the primary focus of Transformation, in the creation of replacement systems requires a target development methodology and information architecture. Not adhering to a development methodology to guide forward engineering activities will result in new systems that will require re-engineering in the future. Formal top down analysis and design, augmented by the Transformation current systems analysis process, prevents this from occurring.
Another point to keep in mind is that Transformation, more than any other Comsys-TIM stage, cannot be entered in a vacuum. Unless a selected task is being applied to re-document a piece of a system or the user is an expert in redevelopment, Transformation should always be entered via a redevelopment scenario.
The main reason for this is that Transformation is a logical extension of the Inventory/Analysis functional assessment and strategic redevelopment planning tasks. It is also highly dependent on certain Positioning tasks based on early assessment findings. The various approaches available within each Transformation task are much more easily digested when driven by a specific redevelopment scenario.
Bottom up/top down comparison and integration of captured meta-data support a more complete view of redevelopment by producing a model that plays an integral role in the new system. The effort required for these steps within each task mirrors the technical and managerial skills required for any large scale development project. The added variable, however, is the availability of an existing model representing how current systems function today.