Protocols -- By Prakash

Protocol:

Protocol is a special set of rules. An end point in a telecommunication uses protocol when they communicate. This enables computers and software built by different people to be able to communicate in the same language.

Examples:

• Hyper Text Transfer Protocol (HTTP) – Web Browser
• File Transfer Protocol (FTP) – File transfer
• Simple Mail Transfer Protocol (SMTP) – Email
• Internet Protocol (IP) – Packets across the Internet

Hyper Text Transfer Protocol (HTTP) – Web Browser

The Hypertext Transfer Protocol (HTTP) is an application-level TCP/IP based protocol with the lightness and speed necessary for distributed, collaborative, hypermedia information systems (internet).

Following diagram shows where HTTP Protocol fits in communication:

File Transfer Protocol (FTP) – File transfer

File Transfer Protocol is a standard network protocol used to copy a file from one host to another over a TCP-based network, such as the Internet.

Control and Data Connections

FTP uses the client-server model. The client establishes a control connection. When the user enters a command, the client forms a request using the FTP protocol and sends it to the server. Similarly, the server uses the FTP protocol to send a reply.

FTP uses the control connection only to send and receive control messages. It establishes a separate data connection for each file transfer.

Figure: FTP Connections

FTP Commands

FTP has commands that allow users to connect to a remote computer, provide authentication, find out what remote files are available, and to request file transfers.

Figure: FTP commands

FTP Software

Different types of FTP software available: FileZilla, WinSCP, CuteFTP, Fugu, and SmartFTP.

Features

1. Resume a download that did not finish successfully. Good feature for people with slower Internet connections.

2. Multiple file transfers at a time.

3. File transfers are made by simply dragging and dropping files from one pane to the other.

Advantages

1. FTP is used to download files. FTP is much faster than standard HTTP downloads (through browser).

2. FTP is a fast and convenient way to transfer files over the Internet. Many webmasters use FTP for uploading their websites files on their hosting accounts.

3. FTP has built-in error checking, and can restart transfers from the point of failure.

Disadvantages

1. We need to obtain and pay for disk space on an FTP server. This storage space is typically very limited or much more expensive per MB than our service.

2. No automatic backup: We need to remember to back up every day.

3. FTP connections are unreliable and often times out, so we need to resume the connection and figure out which files were not backed up.

4. Files can be corrupted during FTP transfers without our knowledge.

5. Most FTP software is not encrypted and therefore not secure.

6. Many FTP server data centers have only minimal data security features.

7. Downloads are not protected (not recommended for uploading or downloading large files).

8. When using a web browser for an FTP connection, FTP uploads are sometimes very slow.

9. HTTP doesn't have built-in error checking.