WEEK 10

Q1: System maintenance?

Ans: A significant portion of an organisation’s budget for information system does not go to development of new systems but to the maintenance of existing system’s there are four types of maintenance tasks in which expenses vary significantly and activities include changing programme,procedures, documenation,to ensure correct system performance adapting system to changing requirments and making the system operate more efficiently.

            1.Corrective maintenance – requires careful analysis before making changes. Investigation, analysis, design and testing are performed before implementing any solution. Any maintenance work that could affect the system must be performed first in test environment, then migrated to operating system. In this, a user submit a system request that is evaluated, priortized and scheduled by the system adminitrator. If the request is approved the maintenance designs, texts, implements and document a solution. For more serious situation such as incorrect report totals or inconsistent data, a user submits a system request with supporting evidence. Those requests a receive a high priority and a maintenance team begins work on the problem immediately. If there is a worst case like total system failure, the maintenance bypasses the initial steps and tries to correct the failure immediately. A wriiten system request is prepared by user or member of IT department and added to maintenance log. Whwn the maintenance team determines the cause, analyse the problem and designs a permanent solution, the IT responds team updates the test data files, thoroughly test the system and prepare fuel documentation.

2. Adaptive Maintenance: It adds the enhancement to operating system and makes the system easier to use. An enhance is new feature or capability. A user submits a system request i.e. evaluated and priortised by system committee. A maintenance team then analysises, designs, tests and implements the enhancement. It is same as corrective maintenance but requires more IT resoureces.

3. Perfective Maintenance: During system operations, changes in user activity or data patterns can cause a declining in efficiency. Perfective manitenance might be needed to restore performance, improves response time, system efficency and system reliability e.g. input problems might cause a programme to terminate abnormaly.By modifying a data entry process, we can high light errors and notify users  that they must enter proper data.In many organistaion,perfective maintenance is not performed,others are more important.Perfective maintenance cna be performed as a part of another project for eg if a new function mjst be added to a programme, we can include perfective maintenance in addaptive maintenance project.It is usually cost effective during the middle of systems operational life.For this analysts must used technique called software re engineering which uses analytical techniques to identify potential quality and performance improvement in an information system.It is similar to business process re engineering .

4. Preventive maintenance :

It analysis the area where trouble is likely to occur.Like perfective maintenance,the it depatment normally initiates preventive maintenance.It results increase user satisfaction,decreased down time.

   Corrective maintenance repairs flaws in a system design,coding implemention.Adpative maintenance implements change to a system to evolve its functionality to changes business need’s or technologies.Perfective maintenance new features or improves sysytem performance.Preventative maintenance avoids possible future problems.Corrective maintenance must be made and usually quiclky.Adaptive maintenance also usually msut be done.Some adpative maintenance and all perfective and preventaive maintenance are discretionary and must be categorized and prioritised.

 

WEEK 9

Q1: Data conversion

Ans: There are four methods of data conversion firts is direct cut over: It is putting new information system online and getting one old system which involves more risk least expresive new system to occur immediately when the new system becomes operational.For eg : consider a payroll system that produce output on weekly basis.Some employees are paid twice a month to the system operates semimonthly.Monthly,quaterly annula reports,also require the system to produce output at the end of every month , quarter and year

                       To minimise the need require information form both old and new systems,cyclical information system are convereted using the direct customer method at the beggining of quarter, calanderyear or first year.

   Second is the parallel operation: change over method requires  that both old/new IS operate fully has a specified period.Data is pinput into both system and output generated by new system is compared to equilent output from old system.When users/managment satsified that new system is terminiated lowrisk , burdened.It is a costly process and it needs temporary employees to handle extra work load.

Third is Pilot operation: It involves implementing the complete new system at selected location of the company. For eg a new sales reporting system might be implemented in only one branch office,or a new payroll system might be  installed in only one department.The group that uses the new system first is called the pilot site.During pilot operation,old system continues to operate entire organistaion including pilot site.After the system proves successul at the pilot sight,it is implemented in the rest of organistion, usually using the direct cut over method.Thus pilot operation is a combination of parallel operation and direct cut over methods.It is less expensive and change over period is shorter,

Fourth is Phased operation: It implements the new system in stages or modules for eg instead of impleminting a new manufacturing system all at once,we first install the materials managment subsystem , then production controll , then jobcost amd so on.We can implement these threee sub systems by using any of three change over methods.With faced opeation,we give a part of system to all users , while pilot operation provide entire system but to only some users for eg if a new production controll sub system fails to operate properly,that failure may not effect the new purchasing sub system.

            System implementation and operation:

     The implemantation and operation phase of the SDLC is most expensive and time consuming phase of entire lifecycle.This face is expensive because so many people are involved in the process.It is time consuming because all the work that has to be copmleted through the entire life of the system.During implemantation and operation,physical design specification must be turned into working computer code.Then the code is tested until most of the errors have been detected and corrected, system is installed,user sites are prepared for the new system and users must come to relay on the new system rather than the existing one to get their work done.Even once the system is installed,new features are added to the system,new business requirment and regulations demand system improvements and corrections are made as flaws are identified from there use of the system in new circumstances.These changes will have ripple effects causing rework in many system developments phases.The seven major activites are concerend that coding,testing,installation,documentation,training,support and maintainance.

                     Sometimes despite the best efforts of the system development team to design and built a quality system and to manage the change process i the organistion,the implemantaion effort fails.There are many ways to determine if an implementation has been successful,the two most common and trusted are the extent to which the system is use and user’s stasifaction with the system.

WEEK 8

Q1: Essay on data and process modeling ?

Ans: The system development lifecycle is central to the development of an efficient information system.It has four phases 1.Planning and selection 2.Analysis 3.Design 4.Implentation and operation.Data and process modeling are included in system analysis which is the second phase of SDLC .Structuring system requirments focus on tool analysts which includes data and process modeling.A data flow diagram is common form of process model and entity relationship diagram are commonly used as a tool in data model.A DFD is a graphic that illustrates the movement of data between external entites and the processes and data stores within a system.Although several different tools have been developed for process modeling but DFD is most commonly used today.It shows how , where and when data are used or changed in an information system.Similarly ERD is a model of entites in business enviorment, the relationships or associations among those entities and the attributes or properties of both  the entities and there relationships.Different notations are used for ER diagram but most commonly used is crow’s foot notation.

                  With DFD developers can map how a system will operate,what the system will accomplish and how the system will be implemented.The DFD should reflect the business process outlined in narrative whereas ER is bitmore complicated as this reflect the system.We have to be able to design the entities that will be used a guide to build the application.The varieties of  ERD support various stage of development, beginning with user readable form that allows the validation of design and culminating in versions that are used by developers to validate a design at detailed level.There are different diagramming methodologies for DFD and ERD.DFD is drawn by showing different symbols,sources and destinations are shown by rectangles, process is shown by circle or round cornered rectangle,data store is represented by open ended rectangle and dataflow is shown by an arrow.It is just like planning tool to develop better system.It shows only the relationship between the process and data.However it tends to focus our attention more on processes.

           ERD uses three main constructs : Data entities,Relationships and Their associated attributes.ER is more detailed logical and graphical representation of data for an organisation.An entity is a person,place, object and event in user environment about which the organisation wishes to maintain data.An entity has its own identity which distinguishes it from every other entity.A rectangle is used to represent the entity.There are different relationships shown between these entites.A relationship is an association between  the  instances of one or more entity types that is of interest to the organistaion.The different relationships are one to one relationship which is the most stable , one to many , many to many.There is an important distinction between entity types and entity instances.An entity type is a collection of entities that share common characteristics.And an entity instance is a single occurrence of an entity type.Each entity type has a set of attributes associated with it.An attribute is a property of an entity which is represented by capital letter followed by lower case letter.

                      In DFD there are differnt levels of diagrams like context diagrams or level zero diagram,level 1 diagram and so on.As we move towards higher level  the DFD becomes more confusing and complicated.When we decompose a DFD from one level to next, a conservation principle is at work.We must conserve inputs and outputs to a process at the next level of deconposition.In other words process 1.0 which appeared in level zero diagram must have same inputs and outputs when  decomposed into level 1 diagram.This conservation of inputs nad outputs is called balancing.There are guide lines which includes completeness , consistency,iterative develpoment in drawing DFD’s

         Every tool has its strengths and weaknesses.Every tool is based on certain assumptions about the general naturte of the problem it is intended to solve and those assumptions influence the nature of solution.A DFD is an excellent logical modeling tool because it shows the relationships between processes and data.It tends to focus our attention on processes,and unless fully understand those processes we will have trouble completing the model.ER diagram stresses the data and shows  how the systems primary data entities are related.Both cannot replace each other.’s

Refrences: Business system analysis and design by WILLIAM S DAVIS

                      Essentials of system analysis and design by VALACICH,GEORGE,HOFFER

                     Guidance from sites www.toolbox.com and www.allexperts.com

WEEK 7

Q1: Name one way that data and process modeling are similar?

And: Data model is used to show as many rules about the meaning and interrelationships among data as possible.We begin conceptual data modeling by developing data model for the systemmbeing replaced,if a system exists.This is essintial for planning the conversion of the current files and database into the data base of new system.Where as the process modeling involves graphically representing the processes or actions that capture,manupulate,store and distribute data between a system and its enviorment and among components within a system.Entity realtionship data models are commonly used diagrams that show how data are organised in an information system in the data modeling .  At the same time , a common form of process model is a data flow diagram. Therefore , basically both are same for developing the information system. Actually both are structured analysis techniques used to increase software development productivity.Both had a significant impact on the quality of systems development process.Analysts use both process and data models to establish the specification of an information system.With a supporting tool such as CASE TOOL,process and data models can also provide the bases for the automatic generation of an information system.

                            The digramming methods of DFD and ERD are basically same.Both use simple boxes (entities) with lines (relationship) and an indicatior at the ends of lines to identifiy the type of relatioship.A data flow diagram is graphic that illustrates the movement of data between external entities and the process and data stores with in the system and entity relationship is detailed,logical  and graphical representation of the data for an organistion or business area.

Q2: Name one way that data and process modeling are different?

Ans: The process modeling stresses more on process involves in a system  development where as data modeling stresses more on data and shows how the system’s primary data entite are related.Therefore dataflow diagrams in process modeling cannot replace entity relationship diagram in data modeling.Both have its own importance.The idea is to prepare both because they complement each other.A dataflow programme gives us a good sense of the processes and a somewhat superficial view of data whereas the entity relationship model focuses on the data and often reveals details that were not apparent in the dataflow diagram.

                      To draw a dataflow diagram we use four symbols.Sources and destinations are represented by squares and rectangles.A process is shown by a round cornered recatngle or a circle.A data store is represented by an open ended rectangle and the dataflow is represented by an arrow.Where as in ER diagram,a rectangle is used to represent an entity and a diamond is used to represent the relationship between two or more entites.Different levels are used in developing DFD’s called leveling first is zero level or context diagram which contains only one process , no data stores,four dataflows and three sinks.Next is level one diagram in which DFD is further ,decompose into more processes.In general ,a level n diagram is a DFD that is generated from n nestded decompsitions from level zero diagram.In  ER diagram different keys are used like primary key,candidate key,foreign key and secondary keys.Entites an attributes are used to show a relationship between the data.There are different dergree of relationship such as unary,binary,ternary relationships.

week 5

TOPIC: DATA DESIGN

There are  different guidelines for clear and efficient data files and about logical and physical database design.Logical and physical design has five purposes :

1.Structure the data in subtle structures that are not likely to change over time and that have minimal redundancy.

2. Develop a logical database design that reflects the actual  data requirements that exist in forms and reports of an information system. This is why database design is often done in parallel with the design of  the human interface of an information system.

3. Develop a logical database design from which we can do physical database design.  because most information systems today use relational database management systems, logical database design usually uses a relational database model, which represents data in simple tables with common columns to link related tables.

4. Translate  arelational database model into a technical file and database design.

5.Choose data storage technologies that will efficiently, accurately and securely process database activities.

 Key steps in developing the logical database modeling and design:

1. Develop  a logical data model for each known user interface for the application using normalisation principles.

2. Combine normalised data requirements from all user interfaces into one consolidated logical database model;this step is called view integration.

3. Translate the conceptual  E-R data model for application , developed without explicit consideration of specific user interfaces, into normalised  data requirements.

4. compare the  consolidated logcal database design with the translated E-R model  and produce , through view integration ,one final logical database model for the application.

During physical database design , we use the results of these four key logical database design steps. we also consider definitions of each attribute,descriptions of where  and when data are entered, retrieved, deleted and updated;  expectations for response time and data integrity; and descriptions of the file and database technologies to be used. These inputs allow us to make key physical design decisions including the following:

1.Choosing the storage format called the data type for each attribute from the logical database model; the format is chosen  to minimise storage spaceand to maximise data quality.data type involves choosing length, coding scheme, and potentially many other parameters for each attribute.

2.Grouping attributes from logical database model into physical records.

 3.Arranging related records in secondary memory so that individual  and groups of records can be stored, retrieved and updated rapidly.

4. Selecting media and structures for storing data to make access more efficient

Database structures:

Hierarchical databases: A database consists of set of related files. In a hierarchical database, the file links from hierarchy, for example, in a school, a student’s name and address file firthet links to an academic file, financial file, and an activity file.In this, name and address file is the parent file, and other files are its children. Database access starts at the topof the hierarchy and flows downward, so it is possible to access a student’s academic file starting from his or her name and address record and not vice versa.Note that a parent can have many children but a child can have only one parent.

Network databases: In a network database, the links can describe relationships between any two files in any direction, so a child can have many parents. For example, if the name and address file contains a link to the academic file and academic  file also contains a link to name and address file, a given student’s grade report might be prepared starting with either file.Beacuse links are relatively easy to add to a data structure , the distinction between hierarchical and network databases has practically disappeared.

Relational databases:The files that form a relational database are best visualised as two dimensional tables or spread sheets. In a given file, each column holds a single field and each row holds a single record. Files are linked by pointers  or more generally relations. The relational model has become the de facto micro computer standard and data normalisation suggests logical data structures that are compatible with realational database.

   Today, the hierarchical and network databases are physically more efficient than ralational databases because they can access data more quickly and they utilise less storage space to hold the same amount of data.Current researsh is focused on the relational model, however, many experts expect relational databases to largely supplant the hierarchical and network models.

week4

topic:  THE USER INTERFACE

The user interface is a point in the system where a human being interacts with the computer.The interface can incorporate hardware, software, procedures and data. The interaction can be direct.For example, a user might access a computer through a screen and keyboard. Printed reports and forms designed to capture data for subsequent input are indirect user interfaces. Note that a well designed user interfaces serves as both connector and a separator, kinking the user to computer and protecting the computer from the user.Before we design the user interfaces we must know the user and understand the task to be performed.Much of the information we need is collected during analysis and high level design. Symbols on the system flowchart identify necessary reports , screens, forms and keyboard operations.On the data flow diagram , floe from sources and to destinations might suggest a need for user interfaces. From data dictionary we can compile list of data elements that are input by and output to users.

          The first step in user in interface design is to define the processes, procedures, and other tasks the user must perform. Given a set of tasks, we can design the necessary screens, reports and forms. Next, the dialogues that control the exchange of information between the computer and the user are designed. Finally, a user manual is written to document the various procedures, screens, forms, and dialogues.Much of the information we need  to design the user processes is collected during analysis and high level design and thus can be extracted from the logical model , the flowchart, the data dictionary, the requirements specification and other documentation.

                              At the beginning of the system development life cycle we prepared process descriptios to understand the present system. Near the end of the analysis we studied and documented the processes once againin an effort to define what new system must do.As we near the end cycle and start detailed design, our focus shifts to how each process should be performed.Here the tools must be seme but the intent is different.There are different steps for documenting the processes.

1. List the steps: once we have identified the processes , we can begin design themby listing the steps t5hat should be performed.

2. Identify the input and output data flows: Given the process description, the next step is to identify its input and output  data flows.

3. Identify other process attributes:There is more to understanding the process than just listing its steps, inputs and outputs. A sense of the priorties associated with the various process steps can be important in designing a good system.

4.Walk through the process: Given a preliminary design , the next step is to physically walk through the process with the people who will actually do the work. If the process ask the user to do something that impossible or unrealistic , he or she will tell us . Listen to the users , observe their reactions and change the process as necessary.

5. Document more formally: Once the design settled down, document the process more formally using such tools as structured english or a process flowchart . Many other tools are available, follow your own organisation’s internal standards.

          forms and reports are integrally related to  DFD and ER diagram developed during requirement structuring. A form is business document containing some predefined data and often includes some areas  where additional data are to be filled in. Most forms have a stylized format and are usually not in simple rows and columns. A report is a business document containing only predefined data, it is passive document used solely for reading and viewing. A report is only for reading  and often contains data about multiple unrelated records in a computer file. On the other hand, a form typicallycontains data from only one record or is, at least, based no one record, such as data about one customer, one order,or one student. The guidelines for the design of forms and reports are very similar.

WEEK 3

Q1: What are data models?

Ans: A data model is a representation of organistaional data.The purpose of conceptual data model is to show as many rules about the meaning and interrelationships among the data as possible. A data model describes the rules and policies of the business.A business rule captures how and organisation has chosen to capture and process data.The techniques used for data orientation result in data model that describes the kinds of data needed in systems and business relationships among the data.The most common format used for data modeling is entity-relationship diagraming to show the data in motion and to show the realtionships among data objects.We begin data modeling by developing a new data model for a system being replaced if exists.This is essential for planning the conversation of current files or database into the database of new system.An ER data model evolves from project identfication and selection through analysis as it become more specific and is validated by more detailed analysis of system needs.Entity-Relationships diagrams were first proposed as a means of quickly obtaining, with minimum effort,a good sense of  the structure of database.An entity is an object like a person,group,place,thing or an activity about which data is stored.An entity has its own identity which distingiushes it from every other entity.There is an important distinction between entity types and entity instances.An entity type is a collection of entities that share common properties.Each entity type is given a name.An instance  is a single occurrence of an entity type.Each entity has a set of attributes associated with it.An attribute is a property of an entity that is of interest to the organistion.We use nouns with initial capital letter followed by lower case letters in naming an attribute.In design phase,the final ER model developed in analysis is matched with designs for systems inputs and outputs and is translated into a format that enables physical data storage decisions.It stresses the data and shows how the systems primary data entities are related.

Q2: What are process models?

Ans: Process modeling involves graphicaly representing the processes, or actions that capture, manipulate,store and distribute data between a system and its environment and among components within a system.A common form of a process model is a data flow diagram DFD.A data flow diagram is a graphic that illustrates the movement of data between external entite and the processes and data stores with in a system.It is one of the several structured analysis techniques used to increase software development productivity.In structured analysis,the primary deliverables from process modeling are a set of interrelated data flow They define system’s boundaries.A process or transform is an activity that changes,moves or transformes data and is represented by circle or round cornered rectangle.A data store represents data at rest and implies that data are held between processes.It is shown by open ended rectangle.A data flow represents data in motion and is shown by an arrow.Data cannot legally flow directly from a source to a destination or between a source / destination and a data store unless they pass through an intermediate process. All data flows must begin or end with a process.DFD symbols describe logical not physical entities.There are different levels like 0-level,1-level,diagrams which is called leveling.A DFD tends focus our attention on the processes and somewhat superficial view of data.

Q3: What text book websites are usefull to search?

Ans: System analysis and design by Shelly and Cashman

         Business system’s analysis and design by William S.Davis

        Essentials of system analysis and design by Valacich George and Hoffer.

        Guidance from websites like www.augrohotech.com,www.toolbox.com

week 2

WEEK TWO

Q1 Define system analysis and design

  System anaiaysis is the second and third phase of system development life cycle , which is methodology to develop and support information systems.during system analaysis,the analyst thoroughly studies the organistaion’s current procedures and information systems used to perform tasks such as shipping,orderentry,machine scheduling and payroll.Analysis has several subphases. The first subface involves determining the requirements of teh system.In this subphase,the analysts work with users to determine what the users want from a proposed system.This subphase involves a carefull study of any current systems that might be replaced or enhanced as part of this project.Next we study the requirments and structure them according to there interrelationships,eliminating any redundancies.Third we generate alternative initial designs to match the requirments.Then we compare these alternatives to determine which best meets the requirments.The output of analysis phase is the description of alternative solution recommended by the analysis team

                                   Third phase of SDLC is system design.During system design analysts convert the description of recommended alternative solution into logical and then physical system specifications.We must design all aspect of system from input and output screens to reports,databases and computer processes.Logical design is not tied to any specific hard ware and systems software platform.Logical design concentrates on the business aspects of the system that is how the system will impact the functional units within the organistion.In physical design,we turn logical design into physical or technical specifications.For example , we must convert diagrams that map the origin,flow and processing of data in a system into structured system design that can then be broken down into smaller and smaller units for conversion to instructions written in a progamming language.During physical design the analyst team decides which progamming languages the computer instructions will be written in,which database systems and file structures will be used for the data,and which hardware platform,operating system and network environment the system will run under.The final product of desgin phase is the physical system specifications.

      Q2. What are five types of information systems?

   Ans: Information systems include enterprise computing systems,transanction processing systems,business support system,knowledge managment systems and user productivity systems.Enterprise computing system support company wide data managment requirments.Tramsaction processing systems process data generated by day to day business operations.Business support systems provide job related information support to users at all levels.These systems can analysis transactional data, generate information needed to mange and control business process and provide information that leads to better decision making.Knowledge managment systems simulate huamn reasoning by combinning a knowledge base and inference rules that detrmine how the knowledge is applied.User productivty system include networking,email,voice mail,fax,wordprocessing,database management,spread sheets,intranet and internet access.

Q3: What are the current problems with The Bowen High School Student system?

Ans: The problems with current information system are discovered at student administration.The data is stored in MS Access,MS Excel,MS Word which are not in standardised format.The information can not be shared easliy and it is difficult to do any analysis on it to filter out usefull information.The data is recorded in different formats and the information stored is inconsistent,incomplete and in many cases duplicated.There is also technical problem of maintaining three software pacakges all the time to be able to continue to record,store and assecc information needed.

Q4: What is the detail understaning of information of BHSSRS?

Ans: All the three software packages must be connected with each other so that information can be shared easily and usefull information realted to student and teacher can be filtered out.Data must be recorded in same format so that stroed infprmation is consistent and complete and in standardised form.Teacher detailed information must be in one data base and student detailed information in another database which must be connected to each other so that information related to any one of these two can be find out easily.Managment and finance section is connected to different database which inturn is related to student database which further connected to teacher information .

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