by Allen Bethea

Interstate highways are built to safely accommodate a wide variety of traffic like passenger buses, freight haulers and family vehicles. Likewise, the Internet acts like a general-purpose thoroughfare for businesses, government organizations and individuals to send and receive information. Applicability Statement 2 or AS2 and File Transfer Protocol or FTP are two standards that ensure the smooth, safe and reliable flow of data along the electronic corridors of the Internet.

Intended Usage

While you can use either AS2 or FTP to transfer files, the two protocols were developed for very different audiences. FTP was designed to be an all-purpose file transfer protocol. The goal of its design and evolution as a standard was to ensure the reliable transfer of large or small binary and text files over networks using TCP/IP, the suite of protocols on which the Internet is built. AS2, on the other hand, was designed to meet the demands of business that needed a way to transfer confidential data securely over the Internet. AS2 bypasses the FTP protocol entirely and uses standard World Wide Web HyperText Transfer Protocol -- HTTP -- to get a document from one point to another.


Development of FTP began in the early 1970s, long before the existence of the Internet. Its original Internet Engineering Task Force Request for Comments was published in April 1971. By 1985, FTP had evolved into its present form as a TCP/IP network tool for copying remote files. About twenty years later, RFC 4130 for AS2 was published. AS2 is the second iteration of a format standard for business-data interchange begun in 2002. The AS2 standard grew in part because of a requirement by retailer Wal-Mart that its suppliers use it for business transactions like product ordering, invoicing and shipping.


FTP was design for reliability rather than security. In a standard FTP session, the login information -- including passwords – and the files themselves are sent unencrypted over the Internet. Except for the sessions login, FTP makes no effort to determine the identity of the recipient or source of the files transferred. In contrast, the AS2 standard packages a file with a Secure/Multipurpose Internet Mail Extensions or S/MIME digital signature. This signature identifies the sender of the file and can also be used to encrypt and decrypt the data. AS2 can ensure that the files transferred reach and can be accessed only by the intended recipient.

Product Availability

You can find an FTP program in one form or another on any desktop PC. A command-line version is a standard part of all Windows, Mac OS X and Linux computers. You can use Web browsers like Internet Explorer, Firefox, Chrome or Safari as FTP clients by typing "ftp://" and the FTP server name in the browser's address bar. In addition, you can purchase or download and install free, open-source FTP clients or servers for your computer. On the other hand, if you want to use AS2 to reliably transmit confidential files and documents, you must purchase proprietary software. AS2 is not as mature a technology as FTP. The only way to be certain your AS2 implementation works with that of your intended recipient is for both of you buy your applications from the same vendor or use only certified products.

About the Author

Allen Bethea has written articles on programming, web design,operating systems and computer hardware since 2002. He holds a Bachelor of Science from UNC-Chapel Hill and AAS degrees in office technology, mechanical engineering/drafting and internet technology. Allen has extensive experience with desktop and system software for both Windows and Linux operating systems.

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