Chapter 6.7, Problem 6.5ARQ

Explanation of Solution

Three-tier architecture:

The three-tier architecture is a fundamental design of user computers and servers that contains three major components or tiers such as follows:

• User tier
• Server tier
• Database tier

Role of each tier in above architecture:

User tier:

• This tier contains computers and mobile devices which have web browsers that request the web page to process it.

Server tier:

• It consists of computers that execute web servers and process the requesting application programs.

Database tier:

• It also contains computers that execute DBMS, which process the user request to fetch and store data in the database.

Working methodology of three-tier architecture:

• When user enter an e-commerce website to buy products online, example “www.zulily.com” in their browser, the browser send a request to a computer in the server tire. Server tier computers can execute applications like web server, a commerce server and so on.
• The requested “www.zulily.com” page will be displayed on the user’s computer. If the user had clicked any product such as shoe, then the commerce server will send a request to the DBMS to retrieve shoe’s data from the database.
• Finally the server formats the page with the data and sends that web page to the user’s computer.

SOA:

SOA stands for “Service-Oriented Architecture”. It is a philosophy that states, each interaction among computing devices are referred as services in a prescribed, standard way.

Reason for encapsulation:

According to SOA terms, the work of each department is encapsulated in the department.

• By using SOA philosophies, each department will formally state the services it provides. Similarly each department will officially state the data it supposes to receive with the request and the data it potentials to return as user’s response.
• Hence there is no personal contact between each department.

Advantages of SOA in three-tier architecture:

• SOA services are stated between the web server and the DBMS server on application back end. Therefore, the DBMS server need not do anything while the number and location of the web server gets adjusted.
• Similarly, the web server need not do anything while the number and location of the DBMS server gets adjusted.

Protocol:

A set of rules and structures for organizing communications is referred as protocol.

TCP/IP protocol architecture:

The TCP/IP protocol architecture contains five layers and one or more protocols which are defined in each layer.

• Computer programs are written by data communication and software vendors, which can implement the rules for specific protocol.

Purpose of internet protocols:

HTTP:

HTTP stands for “Hypertext Transfer Protocol”...