Faculty of Foundry Engineering Virtotechnology

System Analysis and Design

IT systems development

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Information systems development

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SDLC

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Alternatives to SDLC

System Analysis and Design

Agenda

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Information systems development Why so often projects fail? Development and implementation of an information system is a huge organizational challenge. Project risks include:  Schedule overruns.  Budget overruns.  Functionality shortcomings.  Slow adoption.  Resources risks that may affect planned costs and benefits.

System Analysis and Design

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Information systems development Why so often projects fail? ERP project costs will include items such as:  Software licenses.  Software, servers, client upgrades.  Network upgrades.  Application development and customization.  IT training.  Support and maintenance contracts.  On-going support and administration. 

System Analysis and Design

 Professional services.

In most cases business unit costs are underestimated. 4

System Development Life Cycle - SDLC

1.

Project initialization

2.

System analysis and feasibility studies

3.

Logical analysis and design

4.

Aquisition or development

5.

Implementation

6.

Operation

7.

Evaluation of the system

8.

Maintenance

The result of each step may be to stop work or to return to one of the earlier stages.

System Analysis and Design

System Development Life Cycle (SDLC) – formal method for developing IS, assuming sequence of following eight stages:

The stages overlap: one stage may start before the previous stage ends. 5

Stage 1: Project initiation. Projects often start when managers have a problem or see an opportunity. Stage 2: Systems analysis and feasibility studies consists of two phases.  Systems analysis is the phase that develops a thorough understanding of the existing organization, its operation, and the problems that organization aims to resolve using information systems. Systems analysis methods include:    

observations, review of documents, interviews, performance measurement.

System Analysis and Design

SDLC

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SDLC 

Feasibility studies determine achievability of the proposed solution and include:  technology,  economics,  legal, ethical, and other constraints.

Stage 3: Logical analysis and design emphasizes the design of system from the user’s point of view and should reflect business priorities and information needs. It identifies information requirements and specifies operations such as input, output, processing and storage. To represent logical processes and data relationships modeling tools such as data flow diagrams and entity-relationship diagrams can be used. The logical design is followed by a physical design.

System Analysis and Design

 organizational factors,

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SDLC - analysis and design methods

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Tools and techniques used to develop a system that supports a top-down approach in which users study the system starting from the highest level of detail and move to the lowest.

System Analysis and Design

Structured tools

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SDLC - analysis and design methods 

Context Diagram graphically depicts the overall system that is being built:  key elements and inputs, outputs, processes,

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A context diagram can be broken down into subsystems, which are depicted using data flow diagrams. Orders filling system

Client

Order’s data Client’s data

Order verification

Data on approved order

Filling system

System Analysis and Design

 the entities in the system (persons, places, things).

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SDLC - analysis and design methods Data Flow Diagrams Provides a closer look at each subsystem that makes up the system. The DFD shows three items:  How data flow in the system (inputs and outputs)  The processes that convert input into output  Where the data are stored in the system (data stores)

System Analysis and Design

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Source: An Introduction to Data Flow Diagrams, http://www.modernanalyst.com/Resources/Articles/tabid/115/articleType/ArticleView/articleId/2009/ An-Introduction-to-Data-Flow-Diagrams.aspx

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SDLC - analysis and design methods An entity relationship diagram (ERD) is a graphical depiction that identifies the entities of a system and their relationships.

System Analysis and Design

Tools used to represent data

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SDLC - analysis and design methods A system flowchart is a chart that shows how data flows in an information system. It also shows the processes, the sequence of the processes, relationships between the processes, and the data required for each process.

Source: Chapter Six Flowcharting, http://highered.mcgraw-hill.com/sites/dl/free/0078025338/933540/Chapter_6_Flowcharting.pdf

System Analysis and Design

Tools used to capture and represent processes

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SDLC - analysis and design methods Tools used to capture and represent processes

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Decision tables are rules that capture the logic in system processes using a set of conditions (IF clauses) and actions (THEN clauses) shown in the form of a table. A decision tree is a graphical representation of steps used to solve a problem. System Analysis and Design

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Source: INFO16029 Lesson 4 - Decision Tables, http://www-acad.sheridanc.on.ca/~jollymor/info16029/week4.html

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SDLC

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IS personnel use the specifications to purchase the hardware and software required for the system. Programmers write code for parts of the system. Technical writers develop documentation and training materials. IS personnel test the system (check whether the system produces desired results under known conditions). Users test prior to the actual implementation.

Stage 5: Implementation is an important stage; the system can fail here even if it has all the specified functionality.   

Users need training. Help desk needs to be created. Conversion from an old system is required.

System Analysis and Design

Stage 4: Development or acquisition the actual development or acquisition of the system.

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SDLC Conversion approaches include:  Parallel conversion: Old and new system run in parallel until new system becomes reliable; costly but safe approach, best suited to critical applications.  Direct cutover: The old system is turned off, and the new system is turned on; less costly but more risky than parallel approach, best suited to noncritical applications.  Pilot conversion: One department or unit serves as a testing ground; good for systems that are moderately critical.  Phased conversion: New system is slowly phased into the operational environment. Large systems often are built from distinct modules, so it may be possible to replace the modules one at a time. Safe and conservative approach, well suited to critical systems.

System Analysis and Design

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System Analysis and Design

Cykl życia – wdrożenie systemu

Survey Results: The Top ERP Implementation Concerns, http://www.carillonfinancials.com/surveys/survey-results-the-top-erp-implementation-concerns

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SDLC Stage 6: Operation. Post production environment.

Stage 8: Maintenance is changes in hardware, software, documentation, or procedures of production system to correct errors. Every system needs two regular types of maintenance:  Fixing of bugs.  Regular system updating.

System Analysis and Design

Stage 7: Post-audit evaluation reviews the stages and processes to determine best practice methods.

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The traditional SDLC approach works best on projects in which users have a clear idea about their requirements. Projects that require major changes in existing processes, through reengineering or development of new processes or those that build upon inter-organizational and international systems using Web technologies indicate a need for alternatives or supplements to conventional SDLC methodology. Some alternatives include:  Prototyping.  Joint application design (JAD).  Rapid application development (RAD).

System Analysis and Design

Alternatives to SDLC

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Prototyping (evolutionary development). Instead of spending a lot of time producing very detailed specifications, the developers find out only generally what the users want. The developers do not develop the complete system all at once. Instead they quickly create a prototype, which either contains portions of the system of most interest to the users, or is a small-scale working model of the entire system. After reviewing the prototype with the users, the developers refine and extend it. This process is continued until the final specifications.

System Analysis and Design

Alternatives to SDLC

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Joint application design (JAD) is a group-based method for collecting user requirements and creating system designs. It is used within the systems analysis and design stages of the SDLC. Unlike the traditional SDLC, where the analysts interview individual users of the new information system to understand their needs JAD has a meeting in which all users meet simultaneously with analysts. During the meeting, all users jointly define and agree upon systems requirements.

Rapid Application Development (RAD) uses prototyping, fourth-generation tools, and close teamwork for developing systems in short time period.

System Analysis and Design

Alternatives to SDLC

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Alternatives to SDLC Many organizations are using approaches that shift the construction of systems from their information systems department to others.

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End-user development: Let users build their own systems. Outsourcing: Outsource the entire systems development process. Purchasing: Let users use off-the-shelf software packages.

System Analysis and Design

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Alternatives to SDLC Outsourcing

Purchasing 

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Buying an existing package can be cost-effective and timesaving in comparison to in-house application development. Leasing is advantageous over buying in those cases where extensive maintenance is required, or where the cost of buying is very high. Precoded application software programs usuallly need customization: modification of software package to meet organization’s unique requirements without destroying the software’s integrity.

System Analysis and Design

Practice of contracting computer center operations, telecommunications networks, or applications development to external vendors. Popular form of outsourcing is cloud computing.

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Alternatives to SDLC Purchasing – a six step vendor selection: 2.

3. 4. 5. 6.

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Identify potential vendors. Determine the evaluation criteria: 

RFP - Request for Proposal,

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List of users.

Evaluate vendors and packages. Choose the vendor and package. Negotiate a contract. Establish a Service Level Agreement (SLA).

Request for Proposal:  Detailed list of questions submitted to vendors of software or other services.

System Analysis and Design

1.

 Determines how well vendor’s product can meet organization’s specific requirements. 23

System Analysis and Design

Advantages and disadvantages

Source: Turban E., Leidner D., McLean E., Wetherbe J., Information Technology for Management. Wiley, 2006.

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