System implementation and maintenance.ppt

《System implementation and maintenance.ppt》由会员分享，可在线阅读，更多相关《System implementation and maintenance.ppt（50页珍藏版）》请在麦多课文档分享上搜索。

1、10.1,System implementation and maintenance,IMS9001 - Systems Analysis and Design,10.2,Implementation (Build),Build and deliver the system,Build, test, install and deliver the new system,User acceptance testing,User Documentation,Technical Design Report,MAINTENANCE,DESIGN,System Vendors,Hardware/ Sof

2、tware,System Owners,User Training,Production System,System and Technical Documentation,System Users,Project Report,10.3,implementation planning Build and test software Build/modify databases, networks etc. finalise documentation prepare the site convert data into required form and media conduct trai

3、ning install system monitor system transition to maintenance mode post-implementation review,Implementing the System,10.4,Systems Implementation,10.5,Distribute Manuals, Test Equipment, Conduct Training, Set up / Convert Files System Installation, Monitor Operations, Secure Acceptance, Run Benchmark

4、 Tests, Tune System Hand over Technical Documentation, Post Implementation Review (What went wrong ?),REVIEW,REVIEW,REVIEW,CONDUCT TRAINING GET SYSTEM READY FOR START-UP,CONDUCT SYSTSEM ACCEPTANCE,WRAP UP,Systems implementation cont.,10.6,Implementation stage of the project requires a great deal of

5、co-ordination with professionals outside the development team Implementation plan will have been developed at earlier stage of project will need to be extended in greater detail must be updated to reflect the current situation Poor planning can cause significant delays in deadline! Tasks finalise ac

6、ceptance checklist complete and confirm training schedule review and revise implementation plan,Implementation Planning,10.7,Documentation describes how a system works to a wide audienceThe four main areas are:Training documentation used specifically during the training sessions especially designed

7、to put the novice user at ease User documentation tells users how to work with the system and perform their tasks may be a user manual, on-line help, quick reference guide etc,Finalise Documentation,10.8,System documentation a communications tool and to review and revise the system during developmen

8、t also facilitates maintenance and enhancement of the system Operations documentation aimed at a centralised operations group (not on-line operators) details what tasks an operator needs to carry out for a particular program,Finalise documentation cont.,10.9,Testing is . “ the process of exercising

9、or evaluating a system by manual or automatic means to verify that it satisfies specified requirements or to identify differences between expected and actual results “ (IEEE, 1983),Testing,10.10,All testing involves the following steps: select what is to be measured by the test decide how it is to b

10、e tested develop the test cases determine the expected or correct results (you must ensure that expected results can be measured - vagueness does not encourage adequate testing) execute the test cases compare actual results to expected results,Testing Steps,10.11,Stages of Testing,10.12,Each module

11、is tested individually Lists what is being tested Lists expected outcome Identifies data to be used all possible combinations Who carries out Module Testing? Programmer - tests at code level Analyst - tests at application level,Module or Unit Testing,10.13,Integration Testing,Verifies that system co

12、mponents work together: data can be lost across interfaces a function may not perform as expected when combined with another function one module can have an adverse effect on another Use an incremental approach to integrate modules- easier to detect and correct errors: Top-down testing Bottom-up tes

13、ting Sandwich testing,10.14,The process of testing the integrated software in the context of the total system it supports Performed after all unit and integration testing is complete Tests conducted at this stage include: Function tests - demonstrate that all the functions specified for the system i

14、n the requirements specification are operational Performance tests - demonstrate that the system meets the non-functional requirements specified.,System Testing,10.15,Performed after all programming and integration testing is finished Test cases must cover every aspect of the systems functionality s

15、hould have a high probability of detecting errors Test plan should be developed from the original specification must include expected results that are measurable,Function Testing,10.16,Compares the integrated modules with the non-functional system requirements such as speed, performance Stress tests

16、 Volume tests Configuration tests Compatibility tests Security tests Documentation tests Timing tests Environmental tests Quality tests Recovery tests Maintenance tests Human factors tests,Performance Testing,10.17,Acceptance Testing,Involves installing the system at user sites and is required when

17、acceptance testing has not been performed on site The test focuses on completeness of the installed system and verification of any functional or nonfunctional characteristics that may be affected by site conditions Testing is complete When the customer is satisfied with the results The system can th

18、en be formally delivered,10.18,Ensure that facilities are adequate: adequate space for all resources, ergonomic furniture, noise reduction, privacy, security, appropriate electrical connections, uninterrupted power, etc. Install the hardware and software required to run the system must be tested to

19、ensure no damage during transportation, product not defective, product changes between purchase and delivery are acceptable etc People responsible Vendor Engineer, Technical Support Group,Prepare the Site,10.19,Current production data needs to be converted Format, Content, Storage Medium Done accord

20、ing to the conversion plan Manual file conversion is a time-consuming task Often needs specially written conversion programs e.g. Database Load Program Record Transformation Program Data must be confirmed to be correct May need to support both old and new systems files can introduce time lag files m

21、ay be out of step,Data Conversion,10.20,Need to consider: who is the audience? what level of detail should be imparted to the audience? who should conduct the training? where should the training be conducted? when should the training be conducted?,Conduct Training,10.21,Training - a complete and con

22、centrated course in system use at the time of delivery Ongoing training needs; new staff, staff changes etc. Training must be planned methods resources should also consider Help during and after installation for new users, infrequent users and users who want to “brush up“,User Training,10.22,Trainin

23、g aids must be easy to use reliable demonstrations and classes documentation on-line help and icons expert users Supportive User Manager who provides training, motivation, support,User training,10.23,Method of installation depends on several criteria Cost - if there are cost constraints certain choi

24、ces are not viable System criticality - if system failure would be disastrous, the safest approach should be selected regardless of cost User computer experience - the more experience the users have, the less necessary it is to delay changeover System complexity - the more complex the system, the gr

25、eater the chance of flaws . a safer approach is better User resistance - need to consider what the users are best able to cope with,Install the System,10.24,AlternativesDirect installation or Abrupt cut-over Parallel installation Phased installation or Staged installation Pilot installation or Singl

26、e Location conversion,Install the System,10.25,Old system,New system,Total cutover,Old system stops and new system starts,Direct Installation (Abrupt Cutover),10.26,This approach is meaningful when the system is not replacing any other system the old system is judged absolutely without value the old

27、 system is either very small and/or very simple the new system is completely different from the old and comparisons would be meaningless Advantages costs minimised Disadvantages high risk,Direct Installation (Abrupt Cutover),10.27,Old and new systems operated concurrently,Parallel Installation,10.28

28、,Old and new systems operated concurrently Cut-over at end of a business cycle Balancing between both systems Advantages risks low if problems occur Disadvantages cost of operating both systems 2.5 times the resources,Parallel Installation,10.29,System installed in stages,Phased Installation (Staged

29、 Installation),10.30,System installed in stages Subsequent stages provide more features Phases or stages need to be identified at general design Advantages lower costs for earlier results benefits can be realised earlier rate of change for users minimised,Phased Installation (Staged Installation),10

30、.31,Disadvantages close control of systems development is essential costs associated with the development of temporary interfaces to old systems limited applicability demoralising - no sense of completing a system.,Phased Installation (Staged Installation),10.32,Old system,New system,Total cutover,O

31、ld system,New system,Old system,New system,Old and new systems operated concurrently,Pilot Installation,10.33,Old and new systems operated concurrently Only part of the organisation tries out the new system The pilot system must prove itself at the test site Advantages risks relatively low if proble

32、ms occur errors are localised can be used to train users before implementation at their own site Disadvantages lack of consistency between different parts of organisation,Pilot Installation,10.34,Monitor user satisfaction with functional requirements with system performance Run benchmark tests Tune

33、system,Monitor Operations,10.35,Most organisations have formal procedures set up A “maintenance“ section is responsible! Procedures should be set up to request maintenance Owners of the new system must be informed of relevant procedures,Transition to Maintenance,10.36,Maintenance,Fix it / Make it be

34、tter,Maintain the new system,Project staff,Problems/New ideas,Technical problems and new technology,PRODUCTION SYSTEM,System Users,Fixes and enhancements,Additional training and documentation,Modifications,back to INITIATION,Escalating maintenance,10.37,Maintenance,Corrective - fix errors Adaptive -

35、 satisfy changing needs Perfective - enhance performance Preventative - fix potential problemsIf the cost of maintenance is too high consider other options: new development, purchase a software package, re-engineer/modify,10.38,Corrects analysis, design and implementation errors Can be the most expe

36、nsive kind of maintenance costs of functions not working correctly having to undo what has been developed Requires immediate attention typically urgent, interfere with normal operations Needs skilled maintenance staff to ensure rapid diagnosis of errors and their correction must have or quickly deve

37、lop high level of familiarity with the system May use software tools for diagnosis,Corrective Maintenance,10.39,To satisfy changes in the environment, changing business needs or new user requirements changes in tax laws, takeovers and mergers, new OS, etc new type of report, new class of customer et

38、c. Less urgent - changes occur over time Adaptive maintenance is inevitable, does add value Maintenance staff need strong analysis and design skills as well as programming skills changes often require a complete SDLC also need good understanding of the system,Adaptive Maintenance,10.40,Pay now or pa

39、y more later defects or potential problems found and corrected before they cause any damage reduce chance of future system failure eg expand number of records beyond needs, standardise formats across platforms A natural by-product of maintenance work - identify and fix any potential problems noted w

40、hile fixing other errors Ideally have periodic (monthly / half-yearly / annual) reviews of system to uncover and anticipate problems,Preventative Maintenance,10.41,To enhance performance, maintainability, usability adds desired features rather than required better run times, faster transaction proce

41、ssing etc. To meet user requirements not previously recognised or given high priority missed in development or not known about considered unimportant Legacy systems (old systems running for at least 10 years) are likely candidates for perfective maintenance May involve technical systems specialists

42、as well as general maintenance staff network specialist to change network design for improved performance,Perfective Maintenance,10.42,Maintainability the ease with which software can be understood, corrected, adapted and enhanced Low maintainability results in uncontrollable maintenance expenses Th

43、e following factors affect maintainability Defects Customers Documentation Personnel Tools Software structure,Cost Elements of Maintenance,10.43,Defects the number of latent or unknown errors existing after system installation influences most maintenance costs, drives all other cost factors few erro

44、rs low maintenance costs Customers the number of customers/users of system more customers, more maintenance effort/cost greater need for high maintainability,Cost Elements of Maintenance,10.44,Documentation quality of system documentation exponential effect on maintenance costs Personnel quality of

45、maintenance personnel highly skilled programmers, typically not original programmers, to quickly understand and carefully change system separate from development? in-house? dedicated end-user support?,Cost Elements of Maintenance,10.45,Tools appropriate automated development tools programming tools,

46、 code generators, debuggers, hardware, CASE, diagnostics, etc reverse engineering for no documentation Software structure quality of software structure and maintainability formalisation of code, comments, versioning structure charts, OO,Cost Elements of Maintenance,10.46,There is a need to measure m

47、aintenance understand quality of development/maintenance effort We measure the following factors number of failures time between each failure type of failure Mean Time Between Failures (MTBF) calculated using number of failures and time between each failure, widely used measure of quality,Measuring

48、Maintenance Effectiveness,10.47,Software Maintenance Life Cycle (SMLC) receive a Maintenance Request transform the Maintenance Request to a Change (analysis) specify the Change (design) develop the Change (code) test the Change train users and run an acceptance test convert and release to operations

49、 update the documentation conduct a Post-Maintenance Review Chapin, 1988,Maintenance Life Cycle,10.48,Review,What went wrong/right? Why?,System Audit Report,Review the system and the project,Project staff,Problems/New ideas,Project issues and system bugs,MAINTENANCE,System Users,Auditor,Fixes and en

50、hancements,Steering Committee,Project Review Report,10.49,A PIR analyses what went right and wrong with a project. It is conducted 2 to 6 months after conversion by a team which includes user reps, development staff, internal auditors and sometimes external consultants - development team is not in c

51、harge look at original requirements and objectives evaluate how well they were met compare costs of development and operation against original estimates (maintenance costs ?) compare original and actual benefits new system reviewed to see whether more of original or additional benefits can be realised,