HEMS monitoring and control language
RFC 1023
Document | Type |
RFC - Unknown
(October 1987; No errata)
Obsoleted by RFC 1076
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Last updated | 2013-03-02 | ||
Stream | Legacy | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | Legacy state | (None) | |
Consensus Boilerplate | Unknown | ||
RFC Editor Note | (None) | ||
IESG | IESG state | RFC 1023 (Unknown) | |
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) |
Network Working Group G. Trewitt Request for Comments: 1023 Stanford C. Partridge BBN/NNSC October 1987 HEMS Monitoring and Control Language This RFC specifies the design of a general-purpose, yet efficient, monitoring and control language for managing network entities. The data in the entity is modeled as a hierarchy and specific items are named by giving the path from the root of the tree. Most items are read-only, but some can be "set" in order to perform control operations. Both requests and responses are represented using the ISO ASN.1 data encoding rules. STATUS OF THIS MEMO The purpose of this RFC is provide a specification for monitoring and control of network entities in the Internet. This is an experimental specification and is intended for use in testing the ideas presented here. No proposals in this memo are intended as standards for the Internet at this time. After sufficient experimentation and discussion, this RFC will be redrafted, perhaps as a standard. Distribution of this memo is unlimited. This language is a component of the High-Level Entity Monitoring System (HEMS) described in RFC-1021 and RFC-1022. Readers may want to consult these RFCs when reading this memo. RFC-1024 contains detailed assignments of numbers and structures used in this system. This memo assumes a knowledge of the ISO data encoding standard, ASN.1. OVERVIEW AND SCOPE The basic model of monitoring and control used in this proposal is that a query is sent to a monitored entity and the entity sends back a response. The term query is used in the database sense -- it may request information, modify things, or both. We will use gateway- oriented examples, but it should be understood that this query- response mechanism can be applied to other entities besides just gateways. In particular, there is no notion of an interactive "conversation" as in SMTP [RFC-821] or FTP [RFC-959]. A query is a complete request that stands on its own and elicits a complete response. Trewitt & Partridge [Page 1] RFC 1023 HEMS Language October 1987 It is not necessary for a monitored entity to be able to store the complete query. It is quite possible for an implementation to process the query on the fly, producing portions of the response while the query is still being received. Other RFCs associated with HEMS are: RFC-1021 -- Overview; RFC-1022 -- transport protocol and message encapsulation; RFC-1024 -- precise data definitions. These issues are not dealt with here. It is assumed that there is some mechanism to transport a sequence of octets to a query processor within the monitored entity and that there is some mechanism to return a sequence of octets to the entity making the query. ENCODING OF QUERIES AND RESPONSES Both queries and responses are encoded using the representation defined in ISO Standard ASN.1 (Abstract Syntax Notation 1). ASN.1 represents data as sequences of <tag,length,contents> triples that are encoded as a stream of octets. The data tuples may be recursively nested to represent structured data such as arrays or records. For a full description of this notation, see the ISO documents IS 8824 and IS 8825. See the end of this memo for information about ordering these documents. NOTATION USED IN THIS PROPOSAL The notation used in this memo is similar to that used in ASN.1, but less formal, smaller, and (hopefully) easier to read. The most important difference is that, in this memo, we are not concerned with the length of the data items. ASN.1 data items may be either a "simple type" such as integer or octet string or a "structured type", a collection of data items. The notation or a "structured type", a collection of data items. The notation: ID(value) represents a simple data item whose tag is "ID" with the given value. A structured data item is represented as: ID { ... contents ... } where contents is a sequence of data items. Remember that the contents may include both simple and structured types, so the structure is fully recursive. There are situations where it is desirable to specify a type but give no value, such as when there is no meaningful value for a particular measured parameter or when the entire contents of a structured type is being specified. In this situation, the same notation is used, Trewitt & Partridge [Page 2] RFC 1023 HEMS Language October 1987Show full document text