retrieve the actual facsimile document, the recipient must use his facsimile terminal. An explanation of this dialogue is given below. [1) This is the same Login to the Facsimile terminal as in Section [2) The user types in the #L BBNE command to access MSG system at that site7 –Ieten receives a header listing of his unread messages.  The user gives the #R 12, #0 command requesting the retrieval and-printing of his facsimile message. The FAXSYS then types the header of the message and afs- r confirmation. I.. ‘ : i – e ‘ ‘… I~a ~ l ” ” – ” ‘usps holiday schedule by someone else
83 1.14  When confirmed by a <CR>, the text portion of the message is r~etrieved a’nd prin’ted on hi~s console. Simultaneously, by using the cross reference number in the text message header [CCA% ] retrieval of the facsimile document is initiated. (5] Here the #0 command takes its effect, and the facsimile document is reproduced. (6) Having retrieved his facsimile message, the user deletes the message, exits from MSG, and closes connections to the Data-Computer, DIALOGUE L<C_ > COMMENTS [I] * UCL FAX-MESSAGE SYSTEM VERSION X.04, YOUR NAME: PASSWORD:.* LOGIN O.K. YILMAZ <CR> ‘t5c”7… TYPE #H FOR HELP <-#L BBNE <CR> (2) Connect to MSG MSG — Version of 1 April Oct Kirstein at ISI’ <<FACSIMILE, PGS:1, ID= CCA% >> “DEMONSTRATION OF UCL FAXSYS Last Read: i4 Oct msgs, 7 disc pages <-#R 12, #0 (CR> (3] Retrieva] <<ID=CCA% >> Confirml (CR> “” Mail from ISIA rcvd at 15 Oct Date: i5-oct From: Kirstein at ISIA [r 4 ] To: Yilmaz at BBNE cc: Kirstein at ISIA Subject: <<FACSIMILE, PGS=I, ID: CCA% >> “DEMONSTRATION OF UCL FAXSYS *.
84 1.15 (TEXT MESSAGE) Retrieval of CCA% is in progress O.K. FAX Me3sage Printed I <-#D 2, #B<CR>(6) DELETING CCA% [Confirm] <CR> Fig. 4 Dialogue for retrieving facsimile Messages 3.5 Generation of Message Code Numbers Since the textual and facsimile information are stored on different Host computers, it is necessary to devise a aross-referencing mechanism, so that messages can be manipulated uniquely. This is achieved in the following way: During the Login procedure to a Tenex, FAXSYS obtains the time and dite of login, which haj the format : DAY – MONTH – YEAR, HOURS – MINUTES – SECONDS.e.g Oct , ] This information is rearranged to form a twelve digit number which is unique to the message being sent. For the example given above the code number becomes : In fact, this code serves two purposes. Firstly as a link between the two portions of a facsimile message, and secondly as an identifier to store the facsimile information on the Data-Computer. However, since the Data-Computer does not accept a number as the first chara7ter in file names, the above code is padded with “CCA%”, thus producing : CCA% This identifier is generated and added into the text message headers before transmisaion. Its use during the storage and retrieval of facsimile data ia discussed in the next section.
85 4 Sarmead Retrieval at CA 4 1 Introduction The Data-Computer [Ref. 3) is a large-scale data storage utility- offering data storage and management services to other computers on ARPANET. The system is intended to be used as a centratie facility for archiving data, for sharing data among the various network hosts, and providing inexpensive on-line storage. The Data-Computer is implemented on dedicated hardware. and co-prises a separate “computing system specialised for data management. Logically the system can be viewed as a “closed box” shared by multiple external processes, and accessed in a standard notation called “Data-Lanauage” (Ref 31. The system is provided with an Ampex Terabit store of 10”12 bits. While this is mainl7 used-for seismic data, it does contain software and hardware ideal for archival storage. Thus it is an excellent vehicle for our experiments. In a paper of this nature it is not possible to enumerate every aspect of the Data-Computer, and our use of its facilities. Therefore, The Tollowing sections are limited to a discussion of the general principles closely related to our application, and the details are kept to a minimum. In Section 4.2 we discuss the directory structures set up in the Data-Computer. Section 4.3 presents the introductory – concepts of file security and password organisation. Section 4.4 describes the dcta structures used for storing facsimile information. And finally in Section 4.5 we discuss the mechanism for ac,’essing the Data-Computer, and translation of user req,,ests into Vata-Zanguage. 4.2 Directory Structure All data, whether being transmitted to or from the Data-Computer, or stored within it, must be formally aescrtbed to the Data-Computer. These data descriptions are kept in the-data7-computer directory which has a tree structure as illusfrated in Fig. 5. The entries in this directory are called “nodes”, and only the bottom-most nodes of any branch can contain data descriptions. There are three kinds of directory nodes. These are: FILE: containing a description of the format in w-ich the data is stored within the Data-Computer.