Data access layer assessment builds on the general system architecture assessment, but identifies the underlying structure of the physical and logical data design across the systems being assessed.
· Identify physical data redundancy and inconsistency within systems being assessed
· Summarize the current data architecture
· Uncover data structure anomalies that could complicate system maintenance and migration efforts
· Identify level of conformance of current data architecture with that of an ideal or target data architecture
The entrance criteria for the data access layer assessment task are listed below.
· Completion of environmental analysis
· Completion of data definition analysis
· Completion of the general system architecture assessment
Note: The following is a top-down activity completed outside the scope of this task.
· Identification of target technical and data architecture by strategic planning team
The personnel and skill requirements necessary to meet the data access layer assessment task objectives are identified below.
· Current Systems Expert
- Knowledge of existing data structures and databases
- Knowledge of existing functional data requirements
- Basic repository update skills
· Target System Functional Expert
- Knowledge of target functional data requirements
Note: Optional based on target data requirements
· Metric Analyst
- Ability to assess & record architectural metrics
· Redevelopment Expert
- Ability to assess application area in respect to stated corporate standards
- Ability to facilitate, gather, analyze and record data access layer analysis results
- Ability to use required or available redevelopment tools
The system components and related inputs required to initiate and complete the data access layer assessment task are listed below.
· Physical system components including:
- Data definition language source
- IMS system DBD and PSB definitions
- IDMS IDD schema definitions
- DB/2 Catalogue definitions
- Data dictionaries if available
Note: Required if active dictionary defines database segments, records, schema, etc.
- Physical file definitions, such as VSAM IDCAMS definition
· System level data flows, system/sub-system interface map and system interface data flows created in general system architectural assessment
· Completed Executive Planning Form 001
· Completed Environmental Analysis Form 003A
· Completed Data Definition Analysis Form 003B
· Environmental analysis inventory lists - particularly data definition component lists including:
- Database definition source (DBD, PSB, IDD, etc.)
- Data file, such as VSAM, definition source
· Completed general architecture assessment section of Architectural Assessment Form 006
· Blank data access layer assessment section of Architectural Assessment Form 006
· Environmental analysis reports showing
- Job/step/executable/source/physical data file
- On-line execution tables (CICS, ACB, etc.)
· Data definition analysis results including
- I/O record groupings list
- Primary I/O record representation layouts
Optional - where available
· Business Area/Data Store Matrix Form 041 defining major data stores that cross functional business area boundaries
· Optionally, populated LTM repository containing baseline system components and related relationships
· If Develop Data Interface Strategy step is invoked, results from Create Enterprise Segmentation Strategy step should be used as guide to interface design
Optional - For systems requiring a change in architecture derived from top-down analysis outside the scope of this task.
· Target architecture based on strategic redevelopment objectives
Support for this task is available from the following environmental analysis and general support tools:
Environmental analyzer
Ability to assess duplicate physical data usage based:
· Produce Data Set to Program I/O analysis
· Produce Database to Program I/O analysis
The additional ability to identify and depict the following information based on automated analysis of data definition language such as:
· IMS DBD structural analysis
· IMS PSB structural analysis
· VSAM structural analysis
· IDMS structural analysis
· Relation DBMS structural analysis
· Other structural analysis tools for physical data structures and databases
Open systems repository
A repository provides the ability to link data structure usage and source programs within the legacy transition meta-model. In this task, the repository is used to trace relationships between data stores. It is also updated to reflect duplicate data store analysis. If this is a Year 2000 project and enterprise segmentation results are stored in LTM, results should be referenced in Develop Data Interface Strategy step.
Spreadsheet
This tool is used to record metric results for this task.
Word processor
This is required to record analysis results.
The data access layer assessment task is comprised of the following task steps:
