RFC 1024 (rfc1024) - Page 2 of 74
HEMS variable definitions
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RFC 1024 HEMS Definitions October 1987
MESSAGE FORMATS
All HEMS values are conveyed between applications and entities using
the High-Level Entity Management Protocol (HEMP) specified in RFC-
1022. All values specified in this memo are passed in the data
sections of HEMP messages. For all message types, the data section
is a SEQUENCE of objects. For requests, these objects are operations
and their operands. Replies contain a sequence of objects retrieved
by a request. Events contain an initial event object followed by an
optional number of objects related to the event.
Messages conforming to this memo should set the link field in the
HEMP CommonHeader to 1, to indicate version 1 of HEMS. The
resourceId field should be set to NULL.
CONTROL LANGUAGE INSTRUCTIONS
The HEMS Monitoring and Control Language defines a suite of
operations which the query processor must be able to perform. These
operations and their operands are ASN.1 objects which are passed to
the query processor over a network connection. The operations and
operands are sent in postfix form (the operation follows the
operands). Operands are pushed onto a stack and are processed when
the operation is encountered.
To ensure that operations are easily recognized in the input stream,
they are all encoded in a single application-specific type. This
type is shown below.
Operation ::= [APPLICATION 1] IMPLICIT INTEGER {
reserved(0), get(1) begin(2), end(3),
get-match(4), get-attributes(5),
get-attributes-match(6), get-range(7),
set(8), set-match(9)
}
When the query processor encounters an Operation object it consults
the value to determine which operation is to be done (e.g., GET).
GENERAL COMMENTS ON OBJECTS STORED IN ENTITIES
The High-Level Monitoring and Control Language requires the object
space to have a tree-shaped type space. Locating a particular object
requires identifying that section of the tree in which the object
resides. (A more detailed explanation of the scheme is given in
RFC-1023).
Partridge & Trewitt