E-commerce Architecture Network Models Wireless Networks and System Design PDF

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E-commerce Architecture Network Models Wireless Networks and System Design Completion...

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E-commerce Architecture, Network Models, Wireless Networks, and System Design Completion

• The huge expansion of online commerce is reshaping the IT landscape. • Internet business solutions must be efficient, reliable, and cost-effective. • Analysts can examine in-house development, packaged solutions, and service providers

In-House Solutions • If a decision is made to proceed with an in-house solution, there must be an overall plan to help achieve the project’s goals. • An in-house solution usually requires a greater initial investment but provides more flexibility for a company that must adapt quickly in a dynamic ecommerce environment.

Guidelines for in-house Ecommerce Site Development • Analyze the company's business needs and develop a clear statement of your goals. • Obtain input from users who understand the business and technology issues involved in the project. • Determine the IT staff's skills and experience to implement the project. • Consider integration requirements for existing legacy system or enterprise resource planning. • Develop the project in modular form. • Connect the application to existing in-house and verify interactivity. • Test every aspect of the site exhaustively.

Benefits of in-house Strategy • Unique website, with a look and feel consistent with the company’s other marketing efforts. • Complete control over the organization of the site, the number of pages, and the size of the files. • Scalable structure to handle increases in sales and product offerings in the future. • More flexibility to modify and manage the site as the company changes. • The opportunity to integrate the firm’s web-based business systems with its other information systems, creating the potential for more savings and better customer service.

Packaged Solutions • If a small company is reluctant to take on the challenge and complexity of developing an Internet commerce site in-house, an alternative can be a packaged solution. • Many vendors, including IBM and Microsoft, offer turnkey systems for companies that want to get an e-business up and running quickly

Service Providers • Another alternative is to use an application service provider (ASP). • ASP provides applications, or access to applications, by charging a usage or subscription fee. • Today, many ASPs offer full-scale Internet business services for companies that decide to outsource those functions.

Network models What are Network Models? Network Model reflects a design or architecture to accomplish communication between different systems. Network models are also referred to as network stacks or proto col suites.

A network model usually consists of layers. Each layer of a model represents specific functionality. Within the layers of a model, there are usually protocols specified to implement specific tasks. There are a number of different network models. Some of these models relate to a specific implementation, such as the TCP/IP network model.

OSI-RM • The International Organization for Standardization (ISO) is a worldwide body that promotes. Standards internationally. In the late 1970s, ISO began work on developing a standard for Multivendor computer interconnectivity. The result, published in the late 1980s, was the Open System Interconnection (OSI) model.

What is an OSI Model? • The OSI model incorporates protocols that can be used to implement a network stack. These protocols are not used extensively largely due to the popularity of the TCP/IP protocol suite. • In thee OSI- RM, each of the layers are numbered 1 through 7 from physical to application layer.

The TCP/IP Network Model • The TCP/IP network model takes its name from two of its protocols, the Transmission Control Protocol (TCP) and the Internet Protocol (IP). • The process of initiating a network communication, like executing telnet hostname, causes the initiator (usually the client) to encapsulate application data, beginning at the top of the model and moving down, for the network transmission. • The information added by each layer is called a header when it is prefixed to the data from the previous layer, and a trailer when it is suffixed.

The TCP/IP Model • Interpreting the header generated by the same layer on the sending system. This process is known as peer-to-peer communication. • For Layer 5, if the underlying Transport layer protocol is the TCP, then the data produced or read by Layer 5 is called a stream; if the underlying Transport layer protocol is the User Datagram Protocol (UDP), then it is called a message. For Layer 4, if the protocol used is TCP, then the data produced or read by Layer 4 is called a segment. Otherwise, if it is UDP, then it is called a packet. The data of Layer 3 is called a datagram; of Layer 2, a frame or cell; and of Layer 1, a signal.

The Hardware Layer The Hardware layer is responsible for exactly that hardware. This includes cables, interface cards, and repeaters. It accepts the data passed to it by the Network Interface layer and prefixes something called the Preamble, which is a well-known sequence of 64 bits used for synchronization purposes. When it finishes its work, it generates a signal to be submitted to the media (electrically based cables in most cases). There are two hardware devices which operate at this layer: repeaters and amplifiers. Consequently, repeaters are employed in electrical communications environments and amplifiers are employed in light-based communications environments. These devices are often called hubs or concentrators.

The Network Interface Layer The Network Interface layer writes both the destination and source physical address into its header during encapsulation. Consequently, it is at this layer that, during deep capsulation, initial decisions are made about whether or not to continue processing an incoming frame up the stack.

The Internet Layer The Internet layer is responsible for a variety of tasks. In order to accomplish these tasks, it uses three principal protocols. The Internet layer produces or reads the Internet layer header. The header contains a lot of information and, in particular, includes the source and destination IP address associated with the packet.

The Transport Layer The Transport Layer is responsible for the end-to-end flow of data. There are two primary protocols used within this layer (TCP and the UDP).

The Application Layer This is the layer where all the applications live. These applications are responsible for understanding the data format as well as interpreting the data.

Wireless Networks A wireless local area network, or WLAN, is relatively inexpensive to install and is well-suited to work groups and users who are not anchored to a specific desk or location. A wireless network is a computer network that uses wireless data connections between network nodes.

Wireless Network Standards • Wireless networks are based on various standards and protocols that still are evolving. • The most popular of these is called IEEE 802.11, which is a family of standards developed by the Institute of Electrical and Electronics Engineers (IEEE) for wireless LANs. • Wireless network speed is measured in Mbps (megabits per second) or Gbps (gigabits per second).

Variants of IEEE 802.11 • The increased speed is accomplished using multiple input/multiple output (MIMO) technology to boost performance. • MIMO relies on multiple data paths, also called multipath design, to increase bandwidth and range.

Wireless Network Topologies 1. Basic Service Set (BSS) - also called the infrastructure mode. A central wireless device, called an access point or wireless access point (WAP), is used to serve all wireless clients. The access point is similar to a hub in the LAN star topology, except it provides network services to wireless clients instead of wired clients. 2. Extended Service Set (ESS) - is made up of two or more Basic Service Set networks. - Roaming automatically allows the client to associate with the stronger access point, allowing for undisrupted service.

Wireless Network Topologies Wireless Trends

• One of the most significant groups is the Wi-Fi Alliance. • According to the site, the Alliance is a nonprofit international association formed in 1999 to certify interoperability of wireless network products. • The stated goal of the Wi-Fi Alliance is to enhance the user experience through product interoperability.

• Another form of wireless transmission called Bluetooth is very popular for shortdistance wireless communication that does not require high power. • Examples of Bluetooth devices includes wireless keyboards, printers, cellphone headsets, and digital cameras, etc.

SYSTEM DESIGN COMPLETION System Architecture marks the End of the System Design phase of SDLC

SYSTEM DESIGN SPECIFICATION Document that presents the complete design for the new information system. Baseline against which the operational system will be measures. Oriented toward the programmers who will use it to create programs. Varies in length, so it could be organized carefully.

Typical System Design Specification Sections

Management Summary • Brief overview of the project for company managers and executives • Outlines the development efforts to date * current status report * summarized project costs * benefits of the new system review * system implementation schedule presentation * highlight issues

System Components

Complete design for new system, including the user interface, outputs, inputs, files, database, and network specification

System Environment Describes the constraints, or conditions, affecting the system, including any requirements that involve operations, hardware, system software, or security.

Implementation Requirements Start-up processing, initial data entry or acquisition, user training requirements and software

Time and Cost Estimates Provides detailed schedules, cost estimates, and staffing requirements for the systems development phase and revised projections for the remainder of the SDLC.

Additional Material Documents from earlier phases can be inserted if they would be helpful to readers. User Approval • Users must review and approve the interface design, report and menu designs, data entry screens, source documents, and other areas of the system that affect them. • When the design for a report is complete, the systems analyst should meet with users to review the prototype, adjust the design if necessary, and obtain written approval. • Securing approvals from users throughout the design phase is very important. • Other IT department members also need to review the system design specification....