Questions And Answers On Systems Analysis And System Design

Question 1: Primary differences between Systems Analysis and System Design

System analysis focuses on collection and assessment of facts, problem identification, and system decomposition. The process is conducted with the aim to study a system to determine its goals (Hoffer, 2012). It is considered as a problem solving technique that ensures system components work as expected to achieve their goals. On the other hand, system design is a planning process a new system by defining its modules to meet specific requirements. System design is preceded by system analysis as the planning process requires a good insight into the existing system to understand its components and how it operates.

The primary activities in system design including designing:

The environment

Application architecture and software

User Interface (UI)

System Interface

Database

System controls and security

The key outputs of System analysis that become primary inputs to system design include:

System requirements: These are guidelines provided in modelling a system that align with the user expectations.

Logical design: It is a concept in which designers arrange data in a set of logical relationships. 

Scope definition: Overview of the boundaries considered when developing the system. The scope defines what should be covered in the system development process.

‘Extending the models’ implies building on the outputs of the system analysis in the design phase. Since the system analysis provide outputs which define system functionality and its components, the design phase focuses on designing the system based on the derivatives of the system analysis process.

High-level design (HLD provides a design of the architecture and the whole system including main modules and sub modules.  The entry criteria for the design is system requirement document and the exit criteria is database design document, project standards, and functional design document (Zott, 2010). HLD divides a system into functions, modules, etc.  On the other hand, low level design (LLD) breaks down the system developed during HLD into modules. During LLD, logic design is completed for the system and program specifications are specified. The entry criteria for LLD is HLD document and the exit criteria is a system specification and unit test plan.

Three Layer Client-Server Architecture is a software architecture pattern in which presentation, business rules, and data storage are separated and maintained as independent modules (Orfali, 2007).

The three tiers in a three-tier architecture include:

Presentation tier: This is the topmost level in the architecture that is involved in displaying information. It communicates with the other two tiers by sending results or requests.

Question 2: Primary activities in System Design

Application tier: This tier plays an instrumental role in controlling the functionality of a system by processing requests.

Data tier: This tier houses database servers which store data. Data stored in this tier is separated from the other tiers.

Some of the hosting alternatives for internet deployment include:

Colocation: It is a secure data center facility where businesses can rent server space in which their servers are kept and are connected to their businesses.

Managed hosting Service: This is a type of internet hosting service in which customers pay to have full control and access to a server without sharing with other clients. Clients can access operating system, hardware, etc.

Virtual hosting service: This is a type of internet hosting service in which clients lease virtual server that is configured to appear as a real server with specific bandwidth, internal memory, CPU capacity, etc. Multiple website owners can access a virtual server and administer it as if they have full control of the server.

Cloud hosting service: This hosting service involves virtual servers whose computing resource is pulled from various networks of physical servers. Clients can use the service offered as much as they need to based on their requirements. Clients buy cloud space in order to use the computing resources offered.

Mobile first design is a web design approach that focuses on designing website layout and navigation for mobile devices before designing for desktop devices with large screens (Fling, 2009). This approach considers the less real estate available in mobile devices hence places an emphasis on organization of content on these devices to ensure they are well laid-out and are readable. In mobile first design, web developers start designing mobile layouts which are followed by tablet layout and then desktop layout. This implies that the website is responsive in all devices and the visual design is optimized for each type of device

“Ready to Implement” level of detail implies that system developers have system requirements that are necessary to implement a system. System design which succeeds system analysis focuses on the design part of the focus system. The design details developed in this process are pre-requisite to system implementation. Thus, system design is an antecedent of system coding which is a part of the implementation process.

Fundamental Design Principle	Definition of Principle
Coupling	Coupling is the degree to which system components depend on each other. For example, in tightly-coupled systems, all associated components must be available for the code to be compiled and executed.
Cohesion	Cohesion is the degree to which elements in system modules belong together. It evaluates the strength of relationship between system elements within a specific module.
Protection from Variation	Protection from variation implies that system modules are safeguarded from changes that may arise from other system modules. As such, change in performance or emerging issues in one module may not affect the functionality of other system components.
Indirection	Indirection is ability to reference specific objects using a container, reference, or name instead of value. The most popular form of indirection is the manipulation of a valued via its memory address.
Object Responsibility	Object responsibility implies that an object must contain the attributes and methods necessary to carry out the services required by the object. This implies an object should possess the capability to perform the services it requires.

A system sequence diagram illustrates a specific scenario of a use case, events generated by actors, order of events, and events that may occur within the system. In system analysis phase, the diagram is tweaked to represent the general overview of a use case and the actors involved. It is transformed to system diagram when changes are made to show events that occur as a result of user interaction with the system.

Question 3: Outputs of Systems Analysis as primary inputs to System Design

The domain model diagram represents system structure by describing attributes and operation of the entities. In system analysis phase, the domain model illustrates the attributes associated with a specific system. It is transformed into a system diagram by including the operation of entities which indicate the functionality of the system.

A method in relation to system design and design classes is a procedure which defines behavior of objects with the classes. The method is needed to make specific type of data useful. It is the action that an object in a design class can be able to perform.

CRC cards are a collection of standard index cards which are divided into three sections. The cards are used a brainstorming tool that is used in software design. They were originally developed for teaching purposes but became popular among software designers who adopted them in software development (Haug, 2008).

Detail Design – Use Case Realization	Definitions
Sequence Diagrams	Sequence diagrams illustrate flow of logic in a system enabling users to document and verify the logic. The diagrams are commonly used for system analysis and design. They are used for dynamic modelling which identifies system behavior.
Communications Diagrams	Communication diagrams are UML diagrams which are used to visually illustrate interaction between objects using sequenced messages.

User centered design (UCD) is a design process which incorporates user needs. UCD process focuses on usability engineering, human factors, and other user-oriented techniques (Garrett, 2010). Its aim is to produce a usable system that satisfies users and minimizes negative impacts on performance and health. UCD principles include:

Designing for users and their tasks: Usable systems are designed to enable users to perform various tasks. An effective system aligns with business goals by focusing on users and their tasks. Throughout system development, designers consider characteristics of the target users, tasks, and working environment.

Consistency: An effective system has a consistent design which reduces the learning requirements for users. This implies that systems have to be designed to be consistent with other computer components in order to enhance interaction.

Adequate navigation: A user-centered system provides adequate and relevant information for users to know the system status. This involves application of consistent mechanism for indicating where users are when using a system. Some of the mechanism used include navigation map, bread-crumbs, overview, etc.

Human- Computer Interface – Key Aspects	Definitions of Key Aspects
Aspect 1: Usability	Usability is a metric of a system’s ability to meet user goals. In system design, usability is a key aspect that influence the ease-of-use of a system among target users.
Aspect 2: Clarity	Clarity is an important aspect that focuses on the capability of a system to enable people to interact with the system by communicating function and meaning.
Aspect 3:Flexibility	Flexibility is an aspect that focus on the ability of a system to integrate changes without affecting user experience or system functionality.

A database schema is a structure that represents the logical view of database. It defines data organization and relations among attributes as well as the constraints applied on the data (Arai, 2009). Database schema enables database designers to have an insight into the database structure as illustrated by the schema diagrams. Database designers relies on the schema to understand the database and optimize it.
Question 18:  

Distributed Database Architectures	Definitions
Single Database Server Architecture	This a network architecture in which each computer connected to the network shares the same database management system (DBMS). One or more database are hosted on the DBMS which runs on a single server.
Replicated Database Server Architecture	This a network architecture in which several databases holding the same copy of data are used. The database copies are hosted by database management systems (DBMSs) which cooperate and run on several servers.
Partitioned Database Server Architecture	In this server architecture, there are multiple distributed database servers whose database schema is partitioned.
Cloud-based Database Server Architecture	In this architecture, databases are hosted on servers which are accessed via the internet (Curino, 2011). The servers are provided by a cloud computing service provider and the DBMSs run on these servers to offer database services.

System Control Types	List as many examples as possible
Integrity Controls	Data validation Encryption
Security Controls	User authentication Access controls Database logs

References

Arai, Z., Kalies, W., Kokubu, H., Mischaikow, K., Oka, H., & Pilarczyk, P. (2009). A database schema for the analysis of global dynamics of multiparameter systems. SIAM Journal on Applied Dynamical Systems, 8(3), 757-789.

Curino, C., Jones, E. P., Popa, R. A., Malviya, N., Wu, E., Madden, S., … & Zeldovich, N. (2011). Relational cloud: A database-as-a-service for the cloud.

Fling, B. (2009). Mobile design and development: Practical concepts and techniques for creating mobile sites and Web apps. ” O’Reilly Media, Inc.”.

Garrett, J. J. (2010). Elements of user experience, the: user-centered design for the web and beyond. Pearson Education.

Haug, A., & Hvam, L. (2008). CRC cards to support the development and maintenance of product configuration systems. International Journal of Mass Customisation, 3(1), 38-57.

Hoffer, J. A. (2012). Modern Systems Analysis and Design, 6/e. Pearson Education India.

Orfali, R., Harkey, D., & Edwards, J. (2007). Client/server survival guide. John Wiley & Sons.

Zott, C., & Amit, R. (2010). Business model design: an activity system perspective. Long range planning, 43(2), 216-226.