This essay has been submitted by a student. This is not an example of the work written by our professional essay writers.
Electronic mail or email is an electronic message transmitted over a network from one user to another. During the 1960s and 1970s many companies who were using mainframe and mini computers also used email facilities on those systems [Email Hist]. Also during this time the US Department of Defense researched into computer networks was well underway, resulting in the embryonic ARPANET -the forerunner to the now global Internet. According to information regarding these early years, the first ARPANET network email message was transmitted in 1971 [Email Hist]. When the Internet (or ARPANET as it was called) was first introduced it didn't take long before 75% of all network traffic was email related. It has come a long way since the advent of the Internet, with billions of emails being sent and received each day. Email has become the way to communicate efficiently, quickly and cheaply. An email can be simply a few lines of text sent from one user to another, or include attachments such as pictures or documents. It can be a newsletter sent to subscribers daily detailing what's happening and when, or an encrypted message sent between government organizations containing classified information (Becta, 2009)
The actual email itself is organised into parts called the header and the body. The header contains information about who sent it, when it was sent, and the subject and size of the message. This is the part that is normally displayed to users before they open the full email; it is often displayed in bold text on one line. When the email is opened it displays the body as well as the header - the body contains the actual message sent.
Attachments are often sent with emails and these are normally displayed as icons within the email that relate to the attached document's type. Alternatively, they may be embedded into the message body.
3.9.2 The client Server for Email
The client carries out the user's interactions with the email server. Clients can appear in various forms:
Application based - these are installed onto users' machines and include Microsoft Outlook and the freely available Outlook Express and Eudora.
Web based - these appear in a web browser's window and include Hotmail, Yahoo and Outlook web client.
3.9.3 Email Server
An email server is typically a combination of processes running on a server with a large storage capacity - a list of users and rules, and the capability to receive, send and store emails and attachments. Most email servers conduct email services by running two separate processes on the same machine. One process is the POP3 (Post Office Protocol 3) server which holds emails in a queue and delivers emails to the client when they are requested. The other is the SMTP (Simple Mail Transfer Protocol) server that receives outgoing emails from clients and sends and receives email from other SMTP servers. These two processes are linked by an internal mail delivery mechanism that moves mail between the POP3 and SMTP servers. When the client calls the email server to send or check for mail it connects to the server on certain TCP/IP ports SMTP on port 25 to send email and when it checks for new email, POP3 on port 110. Figure 6 shows the relationship between the clients, servers, POP3, SMTP and the internet (Becta, 2009).
okFigure 6: The relationship between clients, email servers and the internet
While .NET makes it easy to work with e-mail messages, the process often fails due to improper server setup. Internet Information Services (IIS) uses the standard e-mail protocol Simple Mail Transfer Protocol (SMTP).
TCP/IP ports are used for all kinds of internet jobs: port 80 for serving browsers with web pages and port 21 for file transfers to be routed to the FTP application. Emails usually use port 25 for SMTP and port 110 for POP3.
Figure 7: Server Port Connectivity for SMTP
3.9.4 Email system to send attachments
SMTP can only transmit text - this creates a problem when it comes to sending images, video and other attachments via email. SMTP gets around this problem by using two different methods.
One method is a program called UUencode. UUencode assumes that the file or attachment contains binary information (1s and 0s). It converts this binary information into text using a simple mathematic equation, almost a type of encryption. Once UUencode has converted an attachment into text, it can travel via SMTP. UUencoding does have problems and there are various formats available, some of which are unable to handle multiple attachments. (ASP.NET, 2013)
An alternative to UUencode is MIME (multi-purpose internet mail extensions). MIME was developed because of the need for a system to translate the array of constantly changing attachment formats. MIME works in a similar way to Uuencode, but creates a header that it wraps around each encoded attachment. This allows it to encode images and sound (Becta, 2009).
3.10 Instant Messaging/Web Chat
The phrase "Instant Message" was devised by Paul M. A. Linebarger for a gimmick in the science-fiction stories, he wrote in the 1960s. His instant messages were to be across interstellar distances at speeds faster than that of light. Instant messaging (IM) are technologies that create the possibility of real-time text-based communication between two or more participants over the internet or some form of internal network/intranet. It is important to understand that what separates chat and instant messaging from technologies such as e-mail is the perceived synchronicity of the communication by the user - Chat happens in real-time. Some systems allow the sending of messages to people not currently logged on (offline messages), thus removing much of the difference between Instant Messaging and e-mail.
A chat-room, which typically providers functionalities mentioned below:
Display list of users who are currently in the room.
Provide a way to broadcast messages to all users of the room.
Alert other users by showing a particular users joining and leaving messages.
Give options to the users to establish a private conversation.
In server proxy based architecture, server act as a proxy between clients. All messages received by the server first and then forward to its recipient it is more likely a centralized system, where the server has full control over the clients.
The benefit of this method is that both clients initiate outgoing connections to the server and either one does not require the ability to accept incoming connections on a port that a corporate firewall may block [MTV]. However, in this case, the server generally takes more time to process and forward the messages to the recipient and also there are strong probabilities that the server become overloaded, due to resource constraint. In this case, to solve the problem, the server has to do additional resource management task for better performance.
In server broker architecture, client request the server to give necessary information to communicate with another client. The server may send IP address and port number to the clients; the clients then establish a direct connection between them.
This architecture reduce server load, as messages are not sending to the central server. The architecture is mainly used to transfer files between two clients. However, this method is often blocked by firewalls, as they are usually configured for not to allow incoming connections. Yahoo! Instant Messenger (YIM) is an example of such architecture. YIM client will send the first message via the server and then attempt a direct connection. If the direct connection fails, the client will continue to send messages via the server [MTV]. The minimum configuration and simplest deployment for Group Chat is a single-server topology, which includes the following computers:
A single Group Chat Server running the following three server roles:
Lookup service. The Lookup service provides the chat room address, distributes sessions to Channel Servers, and in multiple-server topologies manages load balancing.
Channel service. The Channel service provides core functionality for Chat Rooms, except for file posting, which is managed through the Web Service.
Web service. The Web service is used to post files to group channels. Internet Information Services (IIS) version 6.0 hosts the Web service.
A computer hosting the Microsoft SQL Server database for storing ongoing and archival chat data, as well as information about categories and channels that are created, user provisioning information from the Group Chat Administration Tool and initial sign-in, and basic configuration information about the Group Chat Servers.
Group Chat client computers. These computers are not required to be 64-bit.
If compliance is required, the single-server topology must also include the following:
Compliance service. If configured, the Group Chat compliance feature archives a comprehensive record of both logged and unlogged group chat activity. IM content is not archived unless archiving is configured in Office Communications Server. In this case, IM content is archived on the Archiving Server.
SQL Server Database. This database can be either the Group Chat database or a separate database on the Compliance Server.
The following figure shows all of the components of a topology with a single Group Chat Server and optional Compliance Server with a separate compliance database.
Figure 8: Single-server Chat topology
An Internet forum is a discussion area on a website. Website members can post discussions and read and respond to posts by other forum members. A forum can be focused on nearly any subject and a sense of an online community, or virtual community, tends to develop among forum members. A forum is also called a message board, discussion group, bulletin board or web forum. However, it differs from a blog, the name for a web log, as a blog is usually written by one user and usually only allows for the responses of others to the blog material. A forum usually allows all members to make posts and start new topics or message board. It is the modern equivalent of a traditional bulletin board, and a technological evolution of the dialup bulletin board system. Message boards are the Web's original social networks, and they still represent an important and growing piece of what people want. From a technological standpoint, forums or boards are web applications managing user-generated content. People participating in an Internet forum can build bonds with each other and interest groups will easily form around a topic's discussion, subjects dealt with in or around sections in the forum.(ASP.NET, 2013)
A thread is a collection of posts, usually displayed - by default - from oldest to latest, although the option for a threaded view (a tree-like view applying logical reply structure before chronological order) can be available. A thread is defined by a title, an additional description that may summaries the intended discussion, and an opening or original post (common abbreviation 'OP', which can also mean original poster) which opens whatever dialogue or makes whatever announcement the poster wished. A thread can contain any number of posts, including multiple posts from the same members, even if they are one after the other. When a member posts in a thread it will jump to the top since it is the latest updated thread. Similarly, other threads will jump in front of it when they receive posts. A thread's popularity is measured on forums in reply (total posts minus one - the opening post) counts. Some forums also track page views.(ASP.NET, 2013)
Forum is also different from a chat room. Members in a chat room usually all chat or communicate at the same time, while members in Choosemate forum post messages to be read by others whenever they happen to log on. Choosemate forums also tend to be more topic-focused than chat rooms.