TOPS (file server)
Encyclopedia
TOPS is a peer-to-peer
LAN
-based file sharing
system best known in its Macintosh
implementation, but also available for Windows and able to interoperate with Unix's NFS
. Originally written by Centram Systems West, the company was purchased by Sun Microsystems
as part of Sun's development of the NFS ecosystem. Sales of TOPS dried up after the introduction of System 7
, which featured a similar file sharing system built-in, and Sun spun off their NFS developments to Sitka.
effort, and was working with two external companies to develop the Apple Filing Protocol
(AFP), built on top of AppleTalk
. Macintosh Office imploded, and one of the two companies, Centram, decided to implement a similar system on their own. This became the first version of TOPS.
When TOPS was originally released there was no peer-to-peer file sharing solution on the Mac. Apple's own solution, AppleShare
, was not released until later, and unlike TOPS it required a dedicated server machine to run on, at least a Mac Plus. For smaller offices TOPS was an attractive low-cost solution, and saw relatively widespread use. Even after the introduction of AppleShare, TOPS managed to hold on to an estimated 600,000 client installs.
TOPS was initially a protocol using a custom set of remote procedure calls and able to talk only between TOPS clients. Launched into a nascent market, TOPS was soon a best-seller. PCs generally lacked networking of any sort, and Centram addressed this problem by introducing a line of LocalTalk
cards for the PC, along with a TOPS client. Files could be exchanged between the two computers, with filename conversion as required. Centram later introduced the "FlashTalk" networking system that used external clocking to improve LocalTalk performance.
(but not open source
) Telnet
terminal for the Mac.
Additionally, the majority of Macintosh systems used LocalTalk (or PhoneNet
) for connectivity, and could not be directly connected to the Ethernet
-based Unix LANs. They worked around this problem by supporting an emerging LocalTalk-to-Ethernet bridging standard known as "KIP", short for Kinetics Internet Protocol. KIP encapsulated TCP/IP packets inside AppleTalk
packets, allowing them to be sent over existing LocalTalk connections. Dedicated KIP-supporting network bridges were available that stripped off the AppleTalk packaging, re-formed the IP packets inside, and sent them out over Ethernet.
One limitation of the TCP stack was that it did not support DNS
, requiring users to type in IP addresses of the peers they wanted to communicate with. In a network of mostly Macs or Windows PCs this was not an issue, as DNS was not widely used with these systems at that time. KIP also reduced the need for DNS, as it allowed a Mac's existing Address Resolution Protocol (AARP) code within AppleTalk to look up the AppleTalk address of the remote peer, and then communicate with the TOPS stack on that machine to find the corresponding IP address.
TOPS also added the new "InBox Personal Connection" e-mail
system, first developed by Symantec
.
in 1991. TOPS had initially competed against the dedicated-server AppleShare, but System 7 included a file sharing server built-in, one that proved to be much faster than then-current versions of TOPS. TOPS sales dwindled and Sun spun off the division as Sitka, before closing it entirely in 1993.
Peer-to-peer
Peer-to-peer computing or networking is a distributed application architecture that partitions tasks or workloads among peers. Peers are equally privileged, equipotent participants in the application...
LAN
Län
Län and lääni refer to the administrative divisions used in Sweden and previously in Finland. The provinces of Finland were abolished on January 1, 2010....
-based file sharing
File sharing
File sharing is the practice of distributing or providing access to digitally stored information, such as computer programs, multimedia , documents, or electronic books. It may be implemented through a variety of ways...
system best known in its Macintosh
Macintosh
The Macintosh , or Mac, is a series of several lines of personal computers designed, developed, and marketed by Apple Inc. The first Macintosh was introduced by Apple's then-chairman Steve Jobs on January 24, 1984; it was the first commercially successful personal computer to feature a mouse and a...
implementation, but also available for Windows and able to interoperate with Unix's NFS
Network File System
Network File System is a network file system protocol originally developed by Sun Microsystems in 1984, allowing a user on a client computer to access files over a network in a manner similar to how local storage is accessed. NFS, like many other protocols, builds on the Open Network Computing...
. Originally written by Centram Systems West, the company was purchased by Sun Microsystems
Sun Microsystems
Sun Microsystems, Inc. was a company that sold :computers, computer components, :computer software, and :information technology services. Sun was founded on February 24, 1982...
as part of Sun's development of the NFS ecosystem. Sales of TOPS dried up after the introduction of System 7
System 7
System 7 is the name of a Macintosh operating system introduced in 1991.System 7 may also refer to:* System 7 , a British dance/ambient band* System 7 , 1991 album* IBM System/7, a 1970s computer system...
, which featured a similar file sharing system built-in, and Sun spun off their NFS developments to Sitka.
Early versions
TOPS was implemented in an era where each computer system featured its own networking protocol and were generally unable to talk to each other. At the time Apple was in the midst of the Macintosh OfficeMacintosh Office
The Macintosh Office was Apple's third failed attempt to enter into the business environment as a serious competitor to IBM. Consisting of three key parts, a network file server, local area network and a network Laser printer, Apple announced Macintosh Office in January 1985 with an ill-fated,...
effort, and was working with two external companies to develop the Apple Filing Protocol
Apple Filing Protocol
The Apple Filing Protocol is a network protocol that offers file services for Mac OS X and original Mac OS. In Mac OS X, AFP is one of several file services supported including Server Message Block , Network File System , File Transfer Protocol , and WebDAV...
(AFP), built on top of AppleTalk
AppleTalk
AppleTalk is a proprietary suite of protocols developed by Apple Inc. for networking computers. It was included in the original Macintosh released in 1984, but is now unsupported as of the release of Mac OS X v10.6 in 2009 in favor of TCP/IP networking...
. Macintosh Office imploded, and one of the two companies, Centram, decided to implement a similar system on their own. This became the first version of TOPS.
When TOPS was originally released there was no peer-to-peer file sharing solution on the Mac. Apple's own solution, AppleShare
AppleShare
AppleShare was a product from Apple Computer which implemented various network services. Its main purpose was acting as a file server, using the AFP protocol...
, was not released until later, and unlike TOPS it required a dedicated server machine to run on, at least a Mac Plus. For smaller offices TOPS was an attractive low-cost solution, and saw relatively widespread use. Even after the introduction of AppleShare, TOPS managed to hold on to an estimated 600,000 client installs.
TOPS was initially a protocol using a custom set of remote procedure calls and able to talk only between TOPS clients. Launched into a nascent market, TOPS was soon a best-seller. PCs generally lacked networking of any sort, and Centram addressed this problem by introducing a line of LocalTalk
LocalTalk
LocalTalk is a particular implementation of the physical layer of the AppleTalk networking system from Apple Computer. LocalTalk specifies a system of shielded twisted pair cabling, plugged into self-terminating transceivers, running at a rate of 230.4 kbit/s...
cards for the PC, along with a TOPS client. Files could be exchanged between the two computers, with filename conversion as required. Centram later introduced the "FlashTalk" networking system that used external clocking to improve LocalTalk performance.
TCP/IP Support
After the Sun purchase, TOPS was given the problem of making a client that could also access Sun file shares using NFS. Centram solved this problem by porting their file sharing protocol to TCP/IP. This was not trivial; neither Mac OS nor Windows supported TCP/IP "out of the box", so what was now the TOPS Division of Sun had to write a complete IP stack for the Mac and Windows. Centram had already written such a stack for their "TOPS Terminal", a freewareFreeware
Freeware is computer software that is available for use at no cost or for an optional fee, but usually with one or more restricted usage rights. Freeware is in contrast to commercial software, which is typically sold for profit, but might be distributed for a business or commercial purpose in the...
(but not open source
Open source
The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
) Telnet
TELNET
Telnet is a network protocol used on the Internet or local area networks to provide a bidirectional interactive text-oriented communications facility using a virtual terminal connection...
terminal for the Mac.
Additionally, the majority of Macintosh systems used LocalTalk (or PhoneNet
PhoneNet
PhoneNet was an implementation of the AppleTalk networking physical layer created by Farallon Computing . Instead of using expensive shielded twisted pair wiring as in Apple's LocalTalk implementation, PhoneNet uses standard four-conductor telephone patch cords and modular connectors, and is...
) for connectivity, and could not be directly connected to the Ethernet
Ethernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....
-based Unix LANs. They worked around this problem by supporting an emerging LocalTalk-to-Ethernet bridging standard known as "KIP", short for Kinetics Internet Protocol. KIP encapsulated TCP/IP packets inside AppleTalk
AppleTalk
AppleTalk is a proprietary suite of protocols developed by Apple Inc. for networking computers. It was included in the original Macintosh released in 1984, but is now unsupported as of the release of Mac OS X v10.6 in 2009 in favor of TCP/IP networking...
packets, allowing them to be sent over existing LocalTalk connections. Dedicated KIP-supporting network bridges were available that stripped off the AppleTalk packaging, re-formed the IP packets inside, and sent them out over Ethernet.
One limitation of the TCP stack was that it did not support DNS
Domain name system
The Domain Name System is a hierarchical distributed naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities...
, requiring users to type in IP addresses of the peers they wanted to communicate with. In a network of mostly Macs or Windows PCs this was not an issue, as DNS was not widely used with these systems at that time. KIP also reduced the need for DNS, as it allowed a Mac's existing Address Resolution Protocol (AARP) code within AppleTalk to look up the AppleTalk address of the remote peer, and then communicate with the TOPS stack on that machine to find the corresponding IP address.
TOPS also added the new "InBox Personal Connection" e-mail
E-mail
Electronic mail, commonly known as email or e-mail, is a method of exchanging digital messages from an author to one or more recipients. Modern email operates across the Internet or other computer networks. Some early email systems required that the author and the recipient both be online at the...
system, first developed by Symantec
Symantec
Symantec Corporation is the largest maker of security software for computers. The company is headquartered in Mountain View, California, and is a Fortune 500 company and a member of the S&P 500 stock market index.-History:...
.
Decline
TOPS' attractiveness was seriously eroded with the introduction of System 7System 7
System 7 is the name of a Macintosh operating system introduced in 1991.System 7 may also refer to:* System 7 , a British dance/ambient band* System 7 , 1991 album* IBM System/7, a 1970s computer system...
in 1991. TOPS had initially competed against the dedicated-server AppleShare, but System 7 included a file sharing server built-in, one that proved to be much faster than then-current versions of TOPS. TOPS sales dwindled and Sun spun off the division as Sitka, before closing it entirely in 1993.