What is the origin of the client server model?

Question

I was wondering if someone knew the origin of the client server model. Where does the term come from (paper, software application, book)?

Answer 1

This is a good question.

It appears that the term server was commonly used already in 1960s. For example, RFC 5, which was published in 1969, already uses the term, and it seems that it was in a common use already back then.

However, the term client in this context seems to be much more recent; the earliest references that I was able to find are from 1978. The following paper seems to be the earliest hit:

• Jay E. Israel et al. (1978): Separating Data From Function in a Distributed File System.

I did not find the full text of this paper. It seems that it was published in the Proceedings of the Second International Symposium on Operating Systems Theory and Practice, which was held in October 1978. A preview is available here; I am quoting the relevant part (emphasis mine):

The distributed file system (DFS) is so named because it is implemented on a cooperating set of server computers which together create the illusion of a single, logical system. The other computers in the network that use the DFS for creating, destroying, and randomly accessing files are called its clients (we employ the term "user" to stand only for human users; programs that access the DFS are always called clients).

This looks like a good candidate of the first paper that uses the client-server terminology. Note the way it is written: the authors clearly assume that the reader is familiar with the term "server", but they are here introducing the unfamiliar term "client"—so strange that they have to justify its use.

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I checked various resources, including the digital libraries of IEEE and ACM, and I was not able to find any hits that predate 1978. However, already in 1979 there was at least one paper that is boldly using the new term "client" in its title. Unsurprisingly, it is citing Israel et al. (1978).

OED knows the term, but again the earliest use is by Isreal et al.

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Edit: Here are some further comments on the term "server". Looking at various papers written in 1960s, it seems that the term "server" was primarily used in the context of queueing theory; there a "server" can be any kind of entity that provides some service.

Whenever a "server computer" was mentioned in computer science papers written in 1960s, it was typically related to the applications of queueing theory in the context of computer systems. Perhaps this is the origin of the term in our field?

I am not sure what is the first instance of a "server" used in this sense without any direct connection to queueing theory.

However, RFC 5 from 1969 that I mentioned above seems to be already using the term "server" in the context of client-server systems and computer networks, without any explicit references to queueing theory. Of course the term "client" was not introduced yet, so they used the words "server-host" and "user-host".

Answer 2

Windows originally had no system at all for networking PCs. Unless, you wish to count direct connection peer to peer which rapidly became unwieldy and unsafe for data storage. Novell stepped into the rather obvious gap and produced what eventually became Novell Netware which was designed to make up for the poor connectivity of early Microsoft products.

Novell more or less invented the idea of the file server and made those capabilities available to DOS and Windows-based systems. The idea was to designate one machine to manage the network and control access to shared devices, such as disk drives and printers. Novell then arranged the various categories.. printers, disks, users, user groups etc. ...in a really intuitive (i.e. EZ to understand) tree/branch structure. An idea which Microsoft still hasn't caught on to...Novell started doing this back in the late 70's and early 80's. Microsoft jumped into the networking biz with NT4.0 somewhere around 1996 but just 'cause your the biggest, don't mean you're the best.