rfc2594.txt

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Network Working Group                                      H. Hazewinkel
Request for Comments: 2594             Joint Research Centre of the E.C.
Category: Standards Track                                 C. Kalbfleisch
                                                             Verio, Inc.
                                                        J. Schoenwaelder
                                                         TU Braunschweig
                                                                May 1999

            Definitions of Managed Objects for WWW Services

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (1999).  All Rights Reserved.

Abstract

   This memo defines a portion of the Management Information Base (MIB)
   for use with network management protocols in the Internet Community.
   In particular it describes a set of objects for managing World Wide
   Web (WWW) services.

Table of Contents

   1 Introduction .................................................    1
   2 The SNMP Management Framework ................................    2
   3 Terminology ..................................................    3
   4 Overview .....................................................    4
   4.1 Purpose and Requirements ...................................    4
   4.2 Relationship to other Standards Efforts ....................    5
   4.3 WWW Services ...............................................    5
   4.4 Document Transfer Protocol .................................    6
   5 Structure of the MIB .........................................    7
   5.1 Service Information Group ..................................    7
   5.2 Protocol Statistics Group ..................................    7
   5.3 Document Statistics Group ..................................    8
   6 Definitions ..................................................   10
   7 Document Transfer Protocol Mappings ..........................   36
   7.1 The HyperText Transfer Protocol ............................   36
   7.2 The File Transfer Protocol .................................   37
   8 Security Considerations ......................................   38
   9 Intellectual Property ........................................   39
   10 Acknowledgments .............................................   39


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   11 Editors' Addresses ..........................................   39
   12 References ..................................................   40
   13 Full Copyright Statement ....................................   43


1.  Introduction

   This memo defines a set of objects for managing World Wide Web (WWW)
   services. This MIB extends the application management framework
   defined by the System Application Management MIB (SYSAPPL-MIB) [23]
   and the Application Management MIB (APPLICATION-MIB) [24]. The MIB is
   also self-contained so that it can be implemented and used without
   having to implement or install the APPLICATION-MIB or the SYSAPPL-
   MIB.

   The protocol statistics defined in the WWW Service MIB are based on
   an abstract document transfer protocol (DTP). This memo also defines
   a mapping of the abstract DTP to HTTP and FTP.  Additional mappings
   may be defined in the future in order to use this MIB with other
   document transfer protocols. It is anticipated that such future
   mappings will be defined in separate RFCs.

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [17].


2.  The SNMP Management Framework

   The SNMP Management Framework presently consists of five major
   components:

    o   An overall architecture, described in RFC 2571 [1].

    o   Mechanisms for describing and naming objects and events for the
        purpose of management. The first version of this Structure of
        Management Information (SMI) is called SMIv1 and described in
        STD 16, RFC 1155 [2], STD 16, RFC 1212 [3] and RFC 1215 [4]. The
        second version, called SMIv2, is described in STD 58, RFC 2578
        [5], RFC 2579 [6] and RFC 2580 [7].

    o   Message protocols for transferring management information. The
        first version of the SNMP message protocol is called SNMPv1 and
        described in STD 15, RFC 1157 [8]. A second version of the SNMP
        message protocol, which is not an Internet standards track
        protocol, is called SNMPv2c and described in RFC 1901 [9] and
        RFC 1906 [10]. The third version of the message protocol is
        called SNMPv3 and described in RFC 1906 [10], RFC 2572 [11] and
        RFC 2574 [12].


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    o   Protocol operations for accessing management information. The
        first set of protocol operations and associated PDU formats is
        described in RFC 1157 [8]. A second set of protocol operations
        and associated PDU formats is described in RFC 1905 [13].

    o   A set of fundamental applications described in RFC 2573 [14] and
        the view-based access control mechanism described in RFC 2575
        [15].

   Managed objects are accessed via a virtual information store, termed
   the Management Information Base or MIB.  Objects in the MIB are
   defined using the mechanisms defined in the SMI.

   This memo specifies a MIB module that is compliant to the SMIv2. A
   MIB conforming to the SMIv1 can be produced through the appropriate
   translations. The resulting translated MIB must be semantically
   equivalent, except where objects or events are omitted because no
   translation is possible (use of Counter64). Some machine readable
   information in SMIv2 will be converted into textual descriptions in
   SMIv1 during the translation process. However, this loss of machine
   readable information is not considered to change the semantics of the
   MIB.


3.  Terminology

   This section defines the terminology used throughout this document.

   o    The 'World Wide Web' (WWW) is a world wide information system
        which is based on the concept of documents that are linked
        together by embedding references (links) to other local or
        remote documents.

   o    A 'document' is a coherent piece of data which is accessible in
        the World Wide Web. No assumptions are made about the content or
        the type of a document.

   o    A 'Uniform Resource Locator' (URL) is a formatted string
        representation for a document available via the Internet. URLs
        are used to express references between documents. For the syntax
        and semantics of the URL string representation refer to RFC 2396
        [18]

   o    A 'Document Transfer Protocol' (DTP) is a protocol used within
        the World Wide Web to invoke actions on documents. The DTP is an
        abstraction from real protocols, such as HTTP [19,20] or FTP
        [21].




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   o    A 'request' is a DTP protocol operation which is targeted to a
        'document' and invokes an action on the target document.  The
        request type specifies the action that should be performed. A
        request can have a document associated with it.

   o    A 'response' is a DTP protocol operation which is returned as a
        result of a previous (and associated) request. The response
        status indicates if the requested action was successful or if
        errors occurred. A response can have a document associated with
        it.

   o    A 'WWW service' is a set of actions that can be invoked on a
        document. Typical actions are the transfer of documents or the
        retrieval of administrative information about documents. WWW
        services are provided by means of a DTP. A WWW service can be
        identified by the DTP protocol used to invoke services and the
        transport endpoint used by that protocol.

   o    A 'client' is a program which establishes connections for the
        purpose of sending requests and receiving responses.

   o    A 'server' is a program that accepts connections in order to
        service requests by sending back responses.

   o    A 'proxy' is an intermediary program which acts as both a server
        and a client for the purpose of making requests on behalf of
        other clients.  Requests are serviced internally or by passing
        them on, with possible translation, to other servers.

   o    A 'caching proxy' is a proxy with the capability of locally
        storing responses to associated requests. A caching proxy can
        respond to similar requests with a previously stored response.


4.  Overview

   The World Wide Web (WWW) is a global network of information.
   Information is stored in documents, which can have various formats,
   including hyper-text and multi-media documents. Access to these
   documents is provided by servers which are located all around the
   world and are linked to each other via hyper-links embedded in
   documents.

   The usability of the World Wide Web depends largely on the
   performance of the services realized by these servers. The services
   are typically monitored through log files. This becomes a difficult
   task when a single organization is responsible for a large number of
   services. It is therefore desirable to treat WWW services as objects
   that can be managed by using the Internet network management
   framework [22].


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4.1.  Purpose and Requirements

   The goal of this MIB is to define a standardized set of objects which
   lead to integrated and improved performance and fault management in a
   heterogeneous environment of WWW services. This MIB focuses on the
   service-oriented view. It does not deal with the process oriented
   view, which is covered by the System Application MIB [23] and the
   Application MIB [24].

   This document defines a set of managed objects to monitor WWW
   services for short-term operational purposes, such as problem
   detection and troubleshooting. No attempts are made here to cover
   accounting or hit metering issues.

   The scope of the MIB is further limited by the requirement that an
   implementation conforming to this MIB must be possible without
   putting a huge CPU or memory burden on the WWW server implementation.

   In addition, this MIB does not cover WWW service configuration.
   Server software has become an open market where competing vendors
   constantly invent new features in order to shape their products. It
   is therefore not possible to reach consensus on a common way to
   configure WWW services at this point in time.


4.2.  Relationship to other Standards Efforts

   The WWW Service MIB fits into the application management architecture
   defined in the System Application MIB [23]. The System Application
   MIB and the Application MIB [24] use a process-oriented view, where
   an application is viewed as a collection of processes. The WWW
   Service MIB described in this memo uses a service-oriented view,
   which looks at the services provided by a set of processes.

   The relationship between the process-oriented view and the service-
   oriented view is a many-to-many relationship, because one process can
   implement multiple services and multiple services can be implemented
   by a single set of processes. The Application Management MIB [24]
   contains generic mapping tables, which map back and forth between
   both views.

   The WWW Service MIB interfaces to the Application MIB [24] by using
   the service instance identifier (applSrvIndex) for wwwServiceIndex if
   an applicable instance of applSrvIndex is available. The WWW Service
   MIB is self-contained and can be implemented as a stand-alone module
   if the service-level tables in the Application MIB are not available.





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4.3.  WWW Services

   The MIB is organized around the concept of WWW services. WWW services
   are a set of actions that can be invoked on a document. A WWW service
   is provided or used by either a client, a server or a proxy. Clients
   send out requests for information to server or proxy server. Servers
   receive, process and respond to requests received from clients.
   Servers usually have access to local documents, which can be
   transferred to clients.

   A proxy is a special server, who acts as both a server and a client
   for the purpose of making requests on behalf of other clients. A
   proxy is able to translate between the client and the origin server.
   A proxy might also interact with other information retrieval system,
   like for example databases.

   The MIB defined in this memo distinguishes between outgoing and
   incoming requests and responses. This makes it possible to obtain
   statistics for clients, servers and proxies with a single set of
   objects.

   A special proxy server is the caching proxy, which maintains a cache
   of previously received documents in order to reduce the bandwidth
   used by World Wide Web clients. One interesting piece of management
   information is the percentage of requests that were served from the
   cache of the caching proxy (hits/miss-ratio). This ratio is not
   contained explicitly in this MIB. Instead, the ratio can be derived
   from the objects that count incoming and outgoing requests and
   responses.


4.4.  Document Transfer Protocol

   The MIB is based on the concept of an abstract document transfer
   protocol (DTP). The purpose of the abstract document transfer
   protocol is to make the MIB definitions independent from concrete
   protocols, like the Hypertext Transfer Protocol (HTTP) [19,20] or the
   File Transfer Protocol (FTP) [21].

   The abstract document transfer protocol makes the following
   assumptions about a concrete transfer protocol:

   o    The transfer protocol uses a request/response style of
        interactions.

   o    Every request contains a request type, which defines the
        operations performed by the receiving server. The request type
        is represented by an OCTET STRING. It might be necessary to
        define a translation into an OCTET STRING value for protocols
        that use numbers to identify request types.


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   o    A response contains a status code, which indicates if the
        request was processed successfully or which error occurred. The
        status code is represented as an INTEGER value. It might be