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
