Chapter 6 – Essentials of Design and the Design Activities

Jo Hart
Flashcards by Jo Hart, updated more than 1 year ago
Jo Hart
Created by Jo Hart about 6 years ago
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Chapter 6 – Essentials of Design and the Design Activities

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network diagram – a model that shows how the application is deployed across networks and computers
architectural design – broad design of the overall system structure; also called general design or conceptual design
detail design – low-level design that includes the design of the specific program details
local area network (LAN) – a computer network in which the cabling and hardware are confined to a single location
client-server architecture – a computer network configuration with user’s computers and central computers that provide common services
client computers – the computers at which the users work to perform their computational tasks
server computer – the central computer that provides services (such as database access) to the client computers over a network
Hypertext Markup Language (HTML) – the predominant language for constructing Web pages and which consists of tags and rules about how to display pages
Transmission Control Protocol/Internet Protocol (TCP/IP) – the foundation protocol of the Internet; used to provide reliable delivery of messages between networked computers
three-layer architecture – a client/server architecture that divides an application into view layer, business logic layer, and data layer
view layer – the part of the three-layer architecture that contains the user interface
business logic layer or domain layer – the part of a three-layer architecture that contains the programs that implement the business rules and processes
data layer – the part of a three-layer architecture that interacts with the data
Hypertext Transfer Protocol Secure (HTTPS) – an encrypted form of information transfer on the Internet that combines HTTP and TLS
Transport Layer Security (TLS) – an advanced version of Secure Sockets Layer (SSL) protocol used to transmit information over the Internet securely
content delivery network (CDN) – a set of server computers, separate from the hosting computers, used to deliver such static content as images or videos
hosting – the process of providing physical servers at a secure location and selling those services to other businesses that wish to deploy Web sites
colocation – a hosting service with a secure location but in which the computers are usually owned by the client businesses
virtual server – a method to partition the services of a physical Web server so it appears as multiple, independent Internet servers
cloud computing – an extension of virtual servers in which the resources available include computing, storage, and Internet access and appear to have unlimited availability
Service Level Agreement (SLA) – part of the contract between a business and a hosting company that guarantees a specific level of system availability
Virtual Private Networks (VPNs) – a closed network with security and closed access built on top of a public network, such as the Internet
peer-to-peer connection – when independent computers communicate and share resources without the need of a centralized server computer
What is the primary objective of systems design? The objective of systems design is to define, organize, and structure the components of the final solution system that will serve as the blueprint for construction.
What is the difference between systems analysis and systems design? The objective of systems analysis is to understand the needs and requirements, while the objective of design is to figure out the solution to those needs and requirements. Analysis is to understand the problem, design is to solve the problem. (and implementation is to build the solution.)
List the major elements that must be designed for a new software application. From figure 6-1 the elements that must be designed include:  The application software  The database  The user interface  The network and environment  The security and controls  The system interface
List the models that are used for systems analysis. Analysis models include  Class diagrams  Use case diagrams  System sequence diagrams  Use case descriptions  Activity diagrams  State machine diagrams
List the models that are used for systems design. Design models include  Package diagrams  Nodes and locations diagrams  Design class diagrams  Sequence diagrams  Database schema  User-interface layouts  Security and controls documents  Communication diagrams
What is the difference between user-interface design and system-interface design? User-interface design has to do with designing the screens (and reports) that the users see and interact with. Those require substantial user input and consideration for ease of use. System-interface design has to do with those automated interfaces with other systems and tends to consist of technical specifications.
On a project that uses iterations to develop the system, in which iteration does systems design begin? Explain why. Adaptive projects that use iteration include analysis, design, and implementation in every iteration. So design will begin within the first iteration. Depending on the desire result of the first iteration, the design activities may be primarily high-level structural design, but may also include low-level detailed program design.
What is the difference between architectural design and detail design? Architectural design is sometimes called high-level design. It has to do with the overall structure and configuration of the solution system, including network, applications, databases, and how they all work together. Detailed design focuses on the internal methods and logic of the classes or modules.
Designing the security and controls impacts the design of which other elements? Security and controls affects all other elements of the design and of the system. For example, security is required for the network. Security and controls are required to protect the database. Security and controls are required for the application software to protect from attacks as well as normal input errors.
Describe what is required for database design. The database consists of identifying those classes that are persistent (must exist between executions). It also includes defining attributes (fields), keys, indexes, and relationships between those classes. Finally storage and throughput requirements also impact the design.
What is a LAN? When would it be used in deploying a new system? A LAN is a local area network and is used to refer to the network of computers that exists within an organization at a localized site. Depending on the system, a LAN may be used to allow work stations to access data on a central database server within the local site. Also if the employees that work together must communicate together and “see” each others work, then a LAN configuration is required.
What is three-layer design? Many systems are designed with a view layer, which consists of the user interface, a program logic layer, which contains the business processing, and a data layer, which contains the database and data storage routines.
Describe the contents of each layer in three-layer design. View layer – user interface for inputs and outputs – screens and reports. Logic layer – program logic to process business rules and processes Data layer – stored data in the database and the routines to retrieve and update it
List the different types of client devices in a client/server architecture. Client devices range from desktop workstations to laptops and notebooks to small digital mobile devices such as smart phones. Client devices also would be printers that handle system outputs.
What is the difference between HTTPS and HTTP? HTTP is the Hypertext Transport Protocol to send and receive data over the Internet. HTTPS stands for Hypertext Transport Protocol Secure and adds a layer of security by encrypting the data being sent.
In the use of software over the Internet, what are the two main security issues that must be considered? One security issue is how to protect the data and the system residing on the server computer. In other words the server itself must be made secure. Another security issue is how to protect the data when it is in transit across the Internet. In other words the transmission of the data must also be done in a secure manner.
Describe the primary factors that affect throughput for Internet systems. Several factors affect throughput for Internet systems including:  Server computer power and capacity  Database capacity – both the computer and the database efficiency  The number of computers (e.g. server farms)  The location of the server computers (e.g. content delivery networks)  Internet connections and Internet capacity
List five issues that are important when considering an external hosting company. Important issues include:  Reliability of the hardware environment  Security of both hardware and software  Physical facilities including buildings, connection points, etc  Staff of the hosting company for expertise and ability to respond to problems  Growth of the hosted site and can the hosting company handle the growth
What is the difference between cloud computing and virtual servers? A virtual server environment provides the ability to grow and add servers easily for a client. However, the client is still involved in deciding the number and configuration of the virtual servers. Cloud computing, on the other hand, attempts to provide computing power much like a utility that the customer just uses as much computing capability only when he actually needs it.
Why do companies use colocation facilities? Colocation facilities provide several benefits to a company, which can be summarized by cost savings and increase reliability and security. Colocation companies have specially constructed sites to handle high volumes and which have highly reliable sites with backup equipment. Since the cost of these sites are shared by multiple clients a high level of service and reliability can be provided with less expense than if one company tried to do it all for itself.
Describe the issues to be considered when designing for multiple clients. When designing for multiple clients is the wide range of client devices that must be supported. This affects both software design and environment design.
What is a VPN? Why would a company use a VPN? A VPN is a virtual private network which is a private network but which uses the public Internet as the basic transport mechanism. It includes additional security levels to secure the transmission and use of the Internet. A company would use a VPN if it has information that must be very secure, but must be transmitted to remote locations where the company did not have its own private network lines.
A financial corporation has desktop applications running in several different offices that are all supported by a centralized application bank of two computers. In addition, there is a centralized database, which requires three servers. Draw a network diagram representing this requirement. Note: The problem definition of “several different offices” implies a WAN requirement or an Internet requirement. We will represent the WAN or Internet by the cloud. Various types of client devices are illustrated to indicate that there are multiple types of devices that must be supported.
Describe the differences between HTTPS and a VPN. What kinds of computing and networking situations are better suited to HTTPS? What kind of computing and networking situations are better suited to VPN? HTTPS adds secure transmission to Internet traffic. It establishes an encrypted connection between the client and the server. Then it transmits all data in encrypted form. This kind of connection works well for data that must be secure but that is also used by the general public. For example commercial sites where customers purchase items and pay for them with credit cards is a valid use of HTTPS. It is available to everyone and provides a fairly secure method of transmission. VPN adds another layer of security on top of HTTPS. VPN also requires personalized software and/or hardware to add this additional encryption and protection. Therefore VPN is best used for Private networks where each end of the network is controlled by the same organization. VPN is often used by national security groups such as FBI or military. Corporations also use VPN on internal systems. Computers at both ends of the transmission are owned and controlled by the organization.
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