Case Tools Trisha Cummings

Our Definition of CASE  CASE is the use of computer-based support in the software development process.  A CASE tool is a computer-based product aimed at supporting one or more software engineering activities within a software development process.

History of Case Tools  CASE tools began with the simple word processor which was used for creating and manipulating documentation.  The seventies saw the introduction of graphical techniques and structured data flow diagrams.  Up until this point, design and specifications in pictorial form had been extremely complex and time consuming to change.  The introduction of CASE tools to aid this process allowed diagrams to be easily created and modified, improving the quality of software designs.

 Data dictionaries, a very useful document that holds the details of each data type and processes within a system, are the direct result of the arrival of data flow design and structural analysis made possible through the improvements of CASE tools.  Early graphics packages were soon replaced by specialists packages which enabled editing, updating and printing multiple versions of a design.  Eventually, graphic tools integrated with data dictionary databases to produce powerful design and development tools that could hold complete design cycle documents.  As a final step, error checking and test case generators were included to validate software design. All these processes can know be integrated into a single CASE tool that supports all of the development cycle.

Advantages of CASE Tools  Current trends are showing a significant decrease in the cost of hardware with a corresponding increase in the cost of computer software.  This reflects the labor intensive nature of the software.  Developing effective software packages takes the work of many people and can take years to complete.  Furthermore, small errors in the logic of the programs can have huge consequences for the user.

 CASE tools are an important part of resolving the problems of application development and maintenance.  CASE tools significantly alter the time taken by each phase and the distribution of cost with in the software life cycle.  Software engineers are now placing greater emphasis on analysis and design. Much of the code can now be generated automatically with the development of detailed specifications.  Improvements in both these areas made possible through the use of CASE tools are showing dramatic reductions in maintenance costs.  The power of CASE tools lies in their central repository which contains descriptions of all the central components of the system.  These descriptions are used at all stages of the cycle; creation of input/output designs, automatic code generation, etc.  Later tasks continue to add to and build upon this repository so that by the conclusion of the project it contains a complete description of the entire system.  This is a powerful device which was not feasible before the introduction of CASE tools.

 More specifically CASE tools: ensure consistency, completeness and conformance to standards ensure consistency, completeness and conformance to standards encourage an interactive, workstation environment encourage an interactive, workstation environment speeds up development process speeds up development process allows precision to be replicated allows precision to be replicated reduces costs, especially in maintenance reduces costs, especially in maintenance increases productivity increases productivity makes structured techniques practical makes structured techniques practical

Selection of a CASE Tool  With thousands of tools available the decision of which one will best fit your needs is not an easy one.  The failure or success of the tool is relative to your expectations.  Therefore a clear understanding of the specifications and expectations of the CASE tool are of utmost necessity before beginning your search.  There are three common points of failure; the selection process itself, the pre-requisites of the tool, your business.  As previously mentioned the evaluation and selection of a CASE tool is a major project which should not be taken lightly.

 Time and resources need to be allocated to identifying the criteria on which the selection is to be based.  Next, examine if these expectations are reasonable. Make sure you have a clear understanding of the tools purpose.  There must be a common vision of the systems development environment in which the tools will be used.  Finally, know your organization and its needs. Identify the infra structure and in particular, the level of discipline in the information technology department. Is your selection of a CASE tool compatible with the personalities, and expertise of the individuals who will be using it?  If these three areas are taken into consideration the tools is sure to be a success and offer all the benefits outlined above to your development project.

Selection of a CASE Tool  With thousands of tools available the decision of which one will best fit your needs is not an easy one.  The failure or success of the tool is relative to your expectations. Therefor a clear understanding of the specifications and expectations of the CASE tool are of utmost necessity before beginning your search.  There are three common points of failure; the selection process itself, the pre-requisites of the tool, your business.  As previously mentioned the evaluation and selection of a CASE tool is a major project which should not be taken lightly.

 Time and resources need to be allocated to identifying the criteria on which the selection is to be based. Next, examine if these expectations are reasonable. Make sure you have a clear understanding of the tools purpose.  There must be a common vision of the systems development environment in which the tools will be used.  Finally, know your organization and its needs.  Identify the infra structure and in particular, the level of discipline in the information technology department.  Is your selection of a CASE tool compatible with the personalities, and expertise of the individuals who will be using it?  If these three areas are taken into consideration the tools is sure to be a success and offer all the benefits outlined above to your development project.

Upper (Front-End) CASE Tools  During the initial stages of the system development, analysts are required to determine system requirements, and analyze this information to design the most effective system possible.  To complete this task, an analyst will use data flow diagrams, data dictionaries, process specifications, documentation and structure charts.  When completing these tasks manually, it becomes very tedious to have to redraw the diagrams each time a change is made to the system.  Computerized CASE tools allows for these types of changes to be made very quickly and accurately.

 However, using the old methods, a bigger problem arises when changes need to be made to the system - a change to one diagram may require many changes to occur throughout all the documentation.  For a very large system, it is very easy to forget to make the changes in all documentation, leading to an erroneous representation of the system which could lead to problems during the implementation phase.  By using CASE tool's analysis feature, information shared throughout the flowcharts and documentation can be checked against each other to ensure that they match.  CASE tools are also a very helpful tool to use during the design phase of the system development.  CASE provides tools to help develop prototype screens, reports and interfaces.  These prototypes can then be check and approved by the users and management very quickly.  This avoids the problem of having to redesign the interfaces during the implementation phase, that users do not like or do not complete the task they are suppose to handle.

Lower (Back-End) CASE Tools  Lower CASE tools are most often used to help with the generation of the program code.  Forth generation programming languages and code generators measurably reduce the time and cost needed to produce the code necessary to run the system.  Code generators also produce a high quality of code that is easy to maintain and that is portable (i.e. is easily transferable to other hardware platforms).  Forth generation program code is also much easier to test.  Since forth generation code tends to focus on the logic of the program, there are much fewer lines of code for the programmer to examine and test.

 Fewer lines also aids in the maintenance of the program since fewer lines need to be examined, and only the higher level forth generation code will need to be changed, not the lower level third generation code.  Code generators also have the feature that they are able to interact with the upper CASE tools.  Information that was stored from the upper CASE tools can be accessed using the code generators to aid in the development of the code.  Code generators also allow for specialized code to be inserted into the generated program code.  This allows special features to be designed and implemented into the program.

Credits