Before entering this task, two definitions are important. A function is a group of activities that completely support one aspect of furthering the mission of the enterprise. Discovery of current functions, and the linking of those functions to target functions, drives this task.
But bottom-up functional analysis is impractical without decomposing functions to the next level - the process. A process is a low-level activity that starts and stops, has a specific effect on an entity, is a sub-category of a function and defines "what" is being done in a system.
Two main objectives drive this task. The first is to re-document existing system functionality using formal modeling techniques. This results in a function/process hierarchy diagram. The second is to assess the potential of reusing existing rules under a target architecture by mapping existing functions to a top-down, function hierarchy.
If target architecture mapping is planned, an initial attempt should be made to decompose target functions into their respective processes. This will help analysts map high-level, target functions to derived functions and processes within the current system.
The task supports decomposition of existing functions into subordinate processes to provide a more accurate view of current functionality. This also facilitates a more practical approach for abstracting functions from an implementation-level view of a system.
Task objectives are listed below:
· Document current system functionality in the form of a function hierarchy diagram
Note: Starting at the implementation level forces this activity to occur in reverse in practice.
· Decompose current functions into processes
Optional - based on availability of a top-down function hierarchy
· Identify and review target function hierarchy
· Develop gap analysis between current and target function hierarchy diagram
· Perform an analysis of the potential for functional reuse of current system functions and processes under target application architecture
The Program/Function Gap Analysis figure shows the mapping of existing programs to existing functions and existing functions to target functions. This is a highly analytical task since a function is the highest abstraction of a system and the implementation level is the most granular view of a system. A function is a group of business activities that completely support one aspect of the enterprise.
Top-down analysis offers a cohesive way of defining functions. For current systems, this construct does not translate easily. It is still critical, however, to begin determining if certain processes (a functional derivative) can be extracted from current systems and reused under the target architecture at the planning level. This task facilitates this critical planning step.
The entrance criteria for the function hierarchy analysis task are listed below.
· Completion of environmental analysis of technical assessment
· Completion of process analysis of technical assessment
· Completion of subject area/entity type analysis task of functional assessment
· Completion of general system architecture assessment of functional assessment
· Completion of presentation layer assessment task of functional assessment
· Completion of user backlog requirements assessment
Optional - based on redevelopment objectives
· Completion of a top-down, function hierarchy for this area of the business
· Expansion of target function hierarchy to include basic processes for business area involved in this analysis
Optional - based on availability:
· Completion of Enterprise Redevelopment Planning, business architecture assessment task identifying functional overlap between business areas
· Population of LTM model as completed in entrance criteria tasks
The personnel and skill requirements necessary to meet the function hierarchy analysis task are identified below.
· Redevelopment Expert
Note: Review steps in this task to determine specific role requirements.
- Ability to assist with planning and implementing functional assessment
- Ability to perform current system functional analysis through reverse requirements tracing and user/SME interviews
- Ability to perform current to target functional gap analysis
· Current Systems Expert
- Knowledge of existing system functional breakdown
- Knowledge of existing program/function breakdown
· Target System Functional Expert
- Knowledge of target functional requirements
· User Requirements Analyst
- Knowledge of current and target user requirements
· Metric Analyst
- Ability to assess & record functional metrics
· Function Modeling Expert
- Expert at building top-down and bottom-up function and process hierarchy diagrams
The system components and related inputs required to initiate and complete the function hierarchy analysis task are listed below.
· Target function/process hierarchy diagram for the business area that encompasses the system being assessed
· Inventory of existing programs from environmental analysis and process analysis
· The following reports from environmental analysis
- Program to screen
- Screen to program
· Current system components - particularly program source
· Categorized user backlog requirements
· Completed copies of data entity mapping section of functional assessment Form 005
· Blank copies of system level functional reusability factors section of functional assessment Form 005
· Blank copies of functional mapping Form 004
· DFD(s) showing system level flows and system/sub-system interface maps from general system architecture assessment
· Presentation layer analysis task results including screen/report prints and/or mockups
Optional - where available based on prior assessment tasks.
· Legacy transition meta-model (LTM) populated with all system components and relationships based on use in prior Comsys-TIM tasks
· Current business enterprise level architecture information flow summary DFD
· Business Area/Business Function Matrix Form 042 defining major functions that cross business boundaries
Technologies supporting the function hierarchy analysis task include I-CASE modeling, spreadsheet, project management, open systems repository, and word processing tools. These tools are used to represent information as required by this task.
I-CASE Modeling Tools
I-CASE planning, and optionally analysis, tools capable of defining function and process hierarchies, support this task. The use of an integrated tool set supports the mapping of entities to functions during matrix development in the final task of the functional assessment.
Spreadsheet
This tool is used to record metric results for this task.
Open systems repository
A repository provides an important, yet optional, capability to link business areas, systems and components using the legacy transition meta-model. In this task, the repository is used to establish current function objects and map these logical objects to physical programs. Optionally, current functions may be mapped to target functions to support gap analysis as defined in task guidelines.
Word processor
This is required to record analysis results.
The function hierarchy analysis task is comprised of the following task steps:
Create Current Function & Process Hierarchy Map Functions to Program Source Modules Build Current to Target Function Map Summarize Functional Reusability Analysis
