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diff --git a/doc/rfc/rfc163.txt b/doc/rfc/rfc163.txt new file mode 100644 index 0000000..0701d63 --- /dev/null +++ b/doc/rfc/rfc163.txt @@ -0,0 +1,165 @@ + + + + + + +Network Working Group V. Cerf +Request for Comments #163 19 May 71 +NIC #6775 UCLA - NMC +Categories: D.7 Computer Science +Updates: None +Obsoletes: None + + + DATA TRANSFER PROTOCOLS + +This is an informal statement of material discussed at the SJCC. There +are two peoblems. + + 1. Movement of data from one site to another. + 2. Interpretation of the data at receiving site. + +The first task (1) requires a simple protocol which accomplishes the +following + + 1) Standard connection procedure for connecting + transmitting and receiving processes + + 2) Standard packaging which allows network to + collect the transmitted data stream in the + right order and know when the end of the + file has been reached. + +Standard Connection Procedure + +Suppose every HOST has a process charged with the responsibility of +sending and receiving files between -HOSTS-(processes?)[The Data +Manager]. If the Data Manager offers to listen on a given socket for +file xmt requests, then ICP is sufficient to establish a connection +between a serving Data Manager and a using process. + +We have completely avoided the discussion of data interpretation, and +also the problem of control. For instance, we have not said how a +process can ask the Data Manager to send a file of a par- ticular name, +nor how to end the transmission of a file. This is deferred for later. + +Another desirable ability is to have processes transmit files to each +other independent of the HOST Data Manager. ICP should suffice, for the +creation of a full duplex connection. File naming, and format +interpretation are left to the individual process to solve. + +It is of interest to note that files need not have names. If two +processes are connected, then the file name is in a sense implicit in +the sending and receiving socket pair. One imagines, however, that + + + + [Page 1] + +connections with Data Managers for the purpose of file transmission are +too transient to serve as permanent file names, so information about +file name will be needed by the Data Manager. This information could be +supplied either embedded in the file transmission data stream, or +supplied over a separate control connection established at ICP time. + +It seems reasonable that a Data Manager have a network-wide, fixed +socket number on which it is listening to service data transmission +requests.* In this sense, it acts much like the Network Logger. For +inter-process file transmission, less rigidity seems called for, and we +can leave such decisions to the individual peocesses communicating with +each other. Public processes at serving HOSTS could have known (nia +NIC?) sockets over which file transmission is acceptable. + +Standard Packaging + +We naively imagine that very little in the way of formatting is needed +to move data across the connection. A few bits (8?) at the beginning of +transmission could specify the formatting protocol (e.g. arbitrary bit +string until connection closed, count field + data, break chars, etc.) +Depending on the selected format mode, the appropriate control bits will +or will not appear interspersed betweeen the data bits. Message +boundaries are totally transparent. + +A way of ending the file, possibly without closing the connection, is +useful, although closing the connection after the RFNM from final +"record" sent is received by the sending process might be adequate +(sufficient, but not palatable?) + +---- +*ICP causes sockets to be dynamically assigned for the ensuing +conversation (which might be all 1-way). + + + + + + + + + + + + + + + + + + + + [Page 2] + +Control + +A great many problems come up if the Data Manager serves as a part of +the HOST filling system. For example, the Data Manager must know +whether the process it is serving wants to send a file or receive one. +In either case, some sort of file name + qualifiers (user ID, security +codes, access requested, etc.) will be needed to resolve the usual +access legality, and potential file name ambiguities. This information +can be supplied either within a single full duplex data stream (1 per +ICP request) established by a modified ICP for data transmission. The +former seems simplier, sufficient, and immediately implementable. + +Data transmission between arbitrary processes probably does not need as +much formal control protocol as process-to/from-DM (data Manager) +connection. Ad hoc procedures can be established by trading information +on previously established connections; regularity is nice, so perhaps a +standard set of control protocols can be devised which work, regardless +of the identity of the processes transmitting data. Control data must +be formatted and probably identifiable by prefix codes so that +unnecessary control information can be left out if desired. (I am +thinking specifically of file names.) + +It remains to establish a set of format protocols which permit packaging +of data and identification of control information. This should be the +task of the renamed Data Transmission Committee. + + [ This RFC was put into machine readable form for entry ] + [ into the online RFC archives by Simone Demmel 5/97 ] + + + + + + + + + + + + + + + + + + + + + + + + [Page 3] + |