Network Working Group D. Cantor
Request for Comments: 565 Computer Corporation of America
NIC: 18777 28 August 1973
Storing Network Survey Data at the Datacomputer
In November, 1972, Computer Corporation of America (CCA) and the
Programming Technology Division of the Dynamics Modeling System (DMS)
at M.I.T.'s Project MAC began planning to transmit to CCA's
datacomputer [1] information about the behavior of ARPA network hosts
collected by DMS's program SURVEY [2]. The information was to be
stored at the datacomputer and retrieved by an interactive program
that would address the datacomputer from DMS's PDP-10.
One goal of this joint project was to enable DMS to retain all of the
information that SURVEY collects: SURVEY had been running since late
1971, saving only a short daily summary of its findings and
discarding potentially useful details. A second goal was to discover
and remove shortcomings in the interface between CCA's datacomputer
and a program running at a remote host.
The project was completed last month, and the programs described in
this document have been operating successfully with the datacomputer
since July 10.
Part 1, below, describes SURVEY's output. Part 2 describes a program
that retrieves portions of that output from the datacomputer.
Part 1: The Survey Database
Every twenty minutes, DMS's program SURVEY wakes up and performs the
initial connection protocol from the PDP-10 at DMS to the logger
socket (socket 1) of each 28 network hosts.
SURVEY records a date time, host, status,and response time for each
host. A host may be in one of these states:
undetermined or not surveyed
disconnect from the network or dead
network control program not responding
ICP to logger aborted by the host
ICP to logger timed out by SURVEY after 20 seconds
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RFC 565 Storing Network Survey Data 28 August 1973
logger available and responding within 20 seconds
SURVEY records response times responding in tenths of seconds.
When the data for all 28 hosts has been assembled, SURVEY transmits
that data to CCA's datacomputer. If for some reason the datacomputer
cannot accept the information, it is held at DMS and sent another
time.
The datacomputer's survey database is inverted by host, status,
month, and year. That is to say that the datacomputer maintains
several indices to records of one attempt to establish a full duplex
connection to one host's logger: it maintains one such index for each
host, one for each status, one for each month, and one for each year.
The datacomputer can select records that are specified in boolean
expressions by performing boolean operations on the inversion, and
without consulting the data itself. The inversion thus facilitates
rapid interaction between the survey retrieval program described
below and the survey database at the datacomputer.
SURVEY expresses the record of each attempt to access one host in 17
ASCII characters. The record of one survey then occupies 17 * 28 =
476 characters, and each day the datacomputer receives 3 * 24 * 476 =
34,272 characters from DMS.
Part 2: Retrieving Survey Data
A Program called SURRET, written at DMS in the language MUDDLE,
allows one to selectively retrieve material from the survey data base
stored at the datacomputer [3]. Its user may specify values, groups
of values, or, where appropriate, upper and lower bounds for values
of each of five fields: host name, date, time, response time, and
host status. In addition, one may request that all five fields or
any subset of the five be retrieved. A sample interaction with
SURRET is reproduced below.
The angle brackets, the material they enclose, and '$' (ESC or
altmode) were typed by a person using SURRET. The remainder was
typed by the system. The phrases in quotation marks are,
effectively, SURRET prompts. The status messages beginning with ';'
and '.' were generated by the datacomputer. The column headings and
table were formatted by SURRET using figures retrieved from the
datacomputer.
SURRET generates datalanguage, sends it to the datacomputer, and
processes systems diagnostics and data sent to it from the
datacomputer. The datalanguage generated for the foregoing SURRET
request was:
FOR |SURVEY.LOGTRY, SURVEY.LOGTRY WITH
((YEAR EQ '73' AND MONTH EQ '08' AND DAY EQ '05')
AND (HRMIN GE '2000' AND HRMIN LE '2400')
AND (HOST EQ '013'))
HRMIN=HRMIN ; STATUS=STATUS ; RESTIME=RESTIME ;
END;
The field names in the datalanguage were entered with file
descriptors before the first data was loaded.
One can ask SURRET to retrieve new data by changing the values of any
number of fields and issuing a new REQ (request). The command
<state> displays current values for the five prospective retrieval
criteria. Thus:
RFC 565 Storing Network Survey Data 28 August 1973
<REQ ((TIME STATUS RESTIME))>$
;J205 10-08-73 1610:08 RHRUN: SUCCESSFUL COMPILATION
.1241 10-08-73 1610:09 OCSOP: (DEFAULT) OUTPUT PORT OPENED
TIME STATUS R.T.(1/10 SEC)
2004 LOGGER RESPONDING (UP) 020
2024 LOGGER RESPONDING (UP) 008
2044 LOGGER RESPONDING (UP) 008
2104 LOGGER RESPONDING (UP) 009
2124 LOGGER NOT RESPONDING (LNR) 000
2144 LOGGER NOT AVAILABLE(DEAD) 000
2204 NCP NOT RESPONDING (NNR) 000
2224 LOGGER NOT RESPONDING (LNR) 000
2244 LOGGER NOT AVAILABLE (DEAD) 000
2304 LOGGER NOT AVAILABLE (DEAD 000
2324 NCP NOT RESPONDING (NNR) 000
2344 LOGGER RESPONDING (UP) 007
"END OF DATCOMPUTER OUTPUT"
We might have retrieved all of the foregoing output with:
<HOST (CASE-10 OR USC-44)>
Moreover,
<HOST (CASE-10 CCA OR USC-44)>
would cause SURRET to access the database twice, once for information
about Case-10, and then a second time for information about the
remaining two hosts.
Detailed Survey data from July 10, 1973 forward is available either
directly from the datacomputer or through SURRET. Persons who wish
to use the datacomputer directly may obtain the pertinent documents
through the NIC or by contacting Dale Stern at CCA (617-491-3670).
Endnotes
[1] An overview of the data computer is given in Thomas Marill, The
Datacomputer, 18 Oct '71, 7pp. (NIC 7979). A detailed study of the
programming language for addressing the datacomputer is found in
Computer Corporation of America, Datacomputer Project Working Paper
No. 3, Datalanguage, 29 Oct '71, 78 pp. (NIC 8208). The current
status of the language is reviewed in Richard Winter, Specifications
for Datalanguage, Version 0/9, 6 Jun '73, 36 pp. (NIC 16446). A
user's manual for version 0/9, will be released by CCA in September,
1973.
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RFC 565 Storing Network Survey Data 28 August 1973
[2] SURVEY is described in Abhay Bhushan, A Report on the Survey
Project, 22 June '73 (NIC 17375).
[3] A detailed discussion of SURRET is found in Safwan Bengelloun,
MUDDLE Survey Data Retrieval Programs, an internal DMS memo of 14
June, '73. Our purpose here is to describe enough of the program's
syntax and structure to show how it interacts with the datacomputer.
[ This RFC was put into machine readable form for entry ]
[ into the online RFC archives by Via Genie 08/00]
