Irwin/McGraw-Hill Copyright © 2000 The McGraw-Hill Companies. All Rights reserved Whitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS5th Edition 17 C H A P T E R SYSTEMS OPERATION AND SUPPORT

Irwin/McGraw-Hill Copyright © 2000 The McGraw-Hill Companies. All Rights reserved Whitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS5th Edition Chapter Seventeen Systems Operation and Support Define systems operations and support. Differentiate between maintenance, recovery, technical support, and enhancement as system support activities. Describe the tasks required to maintain programs in response to bugs. Describe the role of benchmarking in system maintenance. Describe forms of technical support that a systems analyst provides for the user community. Describe the tasks that should be and may be performed in system enhancement, and the relationship between the enhancement and original systems development process. Describe the role of reengineering in systems enhancement.

Irwin/McGraw-Hill Copyright © 2000 The McGraw-Hill Companies. All Rights reserved Whitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS5th Edition Chapter Map

Irwin/McGraw-Hill Copyright © 2000 The McGraw-Hill Companies. All Rights reserved Whitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS5th Edition An operational system is frequently called a production system. Support versus Operation Systems support is the on- going technical support for users, as well as the maintenance required to fix any errors, omissions, or new requirements that may arise. Systems operation is the day- to-day, week-to-week, month-to- month, and year-to-year execution of an information system’s business processes and application programs.

Irwin/McGraw-Hill Copyright © 2000 The McGraw-Hill Companies. All Rights reserved Whitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS5th Edition The Context of Systems Operation and Support 65-70% of life cycle here in maintenance! Maintenance is GOOD!! Typically place where entry-level programmers start…. Put ‘new sharp person’ where??

Irwin/McGraw-Hill Copyright © 2000 The McGraw-Hill Companies. All Rights reserved Whitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS5th Edition Systems Development, Operation, and Support Three key data stores dealing with development, operations and support. Not sequential tasks Parallel, on-going activities.

Irwin/McGraw-Hill Copyright © 2000 The McGraw-Hill Companies. All Rights reserved Whitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS5th Edition Three Important Data Stores The repository is a data store(s) of accumulated system knowledge—system models, detailed specifications, and any other documentation accumulated during systems development. –accumulated during system’s development –Reusable specs, designs, use cases, etc. –Supported (implemented) via automated tools; generally centralized. The program library is a data store(s) of all application programs. –Source programs (handled by software librarian) –Track changes, versions, etc. Lots of tools to help in configuration. The business data is all those data stores of the actual business data created and maintained by the production application programs. –Includes all RDBMSs, conventional files, data warehouses. –Controlled by a data administrator

Irwin/McGraw-Hill Copyright © 2000 The McGraw-Hill Companies. All Rights reserved Whitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS5th Edition Systems Support Activities Support consists of four ongoing activities. Support activities are triggered depending on particular problem. Let’s look at these support activities…

Irwin/McGraw-Hill Copyright © 2000 The McGraw-Hill Companies. All Rights reserved Whitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS5th Edition System Support Activities Program maintenance corrects “bugs” or errors that slipped through the system development process. Fact of life; Good to an extent… System recovery is the restoration of the system and data after a system failure. How do we recover when system fails / crashes? Restart? Technical support is any assistance provided to users in response to inexperience or unanticipated situations. Users WILL require assistance – training, additional documentation, and other unanticipated problems. System enhancement is the improvement of the system to handle new business problems, new technical problems, or new technology requirements. Response to new requirements for new business problems and/or new business requirements; Perhaps new technologies.

Irwin/McGraw-Hill Copyright © 2000 The McGraw-Hill Companies. All Rights reserved Whitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS5th Edition VERY Important…Know this overhead!!!! Causes of program bugs – requiring maintenance: : –Poorly validated requirements. –Poorly communicated requirements. –Misinterpreted requirements. –Incorrectly implemented requirements or designs. –Simple misuse of the programs.

Irwin/McGraw-Hill Copyright © 2000 The McGraw-Hill Companies. All Rights reserved Whitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS5th Edition System Maintenance Objectives To make predictable changes to existing programs to correct errors. To preserve those aspects of the programs that were correct, and to avoid “ripple effects” of changes that may adversely affect the correctly functioning aspects. To avoid, as much as possible, the degradation of system performance. To complete the task as quickly as possible without sacrificing quality and reliability of the system.

Irwin/McGraw-Hill Copyright © 2000 The McGraw-Hill Companies. All Rights reserved Whitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS5th Edition Need to have understanding of the programs and applications. Most system maintenance is program maintenance!! So, what are the key tasks of Program Maintenance…

Irwin/McGraw-Hill Copyright © 2000 The McGraw-Hill Companies. All Rights reserved Whitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS5th Edition System Maintenance Tasks Shows affected databases and tasks…

Irwin/McGraw-Hill Copyright © 2000 The McGraw-Hill Companies. All Rights reserved Whitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS5th Edition System Maintenance Tasks 1.Validate the problem. 1.reproduce the problem. 2.FAB / Customer Service – send console printouts, dumps, etc. 3.If not reproducible, when occurs again, record everything!!!! 4.Could be incorrect use of system 5.Otherwise, a true bug 1.If so, all maintenance performed on COPY of the program. 2.Benchmark the program. 1.Before making any changes to a program ‘having’ a bug, execute and test program some more and establish a baseline against which the modified programs and application can be later measured. 2.Simulate the environment within which the ‘bug’ occurred. 3.Use automated test tools that assist in testing. 1.The test data and benchmarks are stored in a test database. 2.Whole process is recorded as a ‘test script.’ 4.A test script is a repository of test cases to be executed against all program revisions.

Irwin/McGraw-Hill Copyright © 2000 The McGraw-Hill Companies. All Rights reserved Whitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS5th Edition System Maintenance Tasks (continued) 1.All maintenance done to the copy of the program. 2.Fixed program will go back into production as part of next ‘release’ of software. 3.RARELY is the original programmer available to make repairs. 1.System knowledge may not be sufficient 2.If original programmer available, knowledge may be dated. 3.Too, others may have performed maintenance on this program. 4.Can take CONSIDERABLE time… 4.Study and debug the program to fix: 1.Poor program structure. 2.Unstructured (or poorly structured) logic. 3.Prior maintenance (so-called “ripple” effects.) 4.Dead code. 5.Poor or inadequate documentation.

Irwin/McGraw-Hill Copyright © 2000 The McGraw-Hill Companies. All Rights reserved Whitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS5th Edition System Maintenance Tasks (continued) 1.Test the program. 1.Version control is a process whereby a librarian program keeps track of changes made to programs to facilitate backtracking. 2.Some sites use different ‘versions’ of software while, perhaps, newer versions ‘settle down.’ 3.Not at all unusual!

Irwin/McGraw-Hill Copyright © 2000 The McGraw-Hill Companies. All Rights reserved Whitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS5th Edition Types of Testing Before being placed back into operation, much testing must be accommodated. Unit testing (essential) ensures that the stand-alone program fixes the bug without undesirable side effects to the program. System testing (essential) ensures that the entire application, of which the modified and unit tested program was a part, still works as a complete system. Regression testing (recommended) extrapolates the impact of the changes on system performance (throughput and response time) by analyzing before-and-after performance against the test script. Successful testing => program can be ‘released’ next cycle.

Irwin/McGraw-Hill Copyright © 2000 The McGraw-Hill Companies. All Rights reserved Whitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS5th Edition System Recovery Activities (Direct means activities performed or supervised by SA; Indirect means activities coordinated by SA but done by other technical people… Direct: Client-side (end-user) recovery and/or instruction directly from the systems analyst. Indirect: Server-side recovery through a system administrator. Indirect: Database recovery and rollback through a database administrator. Indirect: Network recovery or fix through a network administrator. Indirect: Technical or vendor assistance to correct a hardware problem. Direct: Detection of a software bug (which triggers systems maintenance).

Irwin/McGraw-Hill Copyright © 2000 The McGraw-Hill Companies. All Rights reserved Whitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS5th Edition System Enhancement Triggers Much of this going on for legacy systems nowadays… (really, all systems, as applications adapt to changes!) New business problems - may render part of application unusable. New business requirements – new reports / transactions / policies… New technology requirements (inclusive of hardware and software upgrades) - install on newer machines? New design requirements –add a new field or table to database. These often overlap.

Irwin/McGraw-Hill Copyright © 2000 The McGraw-Hill Companies. All Rights reserved Whitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS5th Edition System Enhancement Activities Sometimes enhancements are easy to do. Other times, they are NOT!! Normally, software documentation (in general) is poorly written or non-existent! If old, perhaps little or no ‘process’ was used for development. Enhancements can require many ‘person years’ of work!!

Irwin/McGraw-Hill Copyright © 2000 The McGraw-Hill Companies. All Rights reserved Whitten Bentley DittmanSYSTEMS ANALYSIS AND DESIGN METHODS5th Edition System Enhancement Tasks 1.Analyze enhancement request. 2.If appropriate, make the quick fix. 1.e.g., report writing 3.Recover the existing physical system: 1.Database recovery and restructuring 2.Program analysis, recovery, and restructuring 1.Software metrics are mathematically proven measurements of software quality and productivity. 1.Measurement of control flow knots (complexity of logic) 2.Measurement of cycle complexity (cyclomatic complexity) 2.Code reorganization of modularity and/or logic 3.Code conversion from one language to another 4.Code slicing to create reusable software components or objects 4.(Repeat appropriate phases and tasks of the original development methodology