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rfc:rfc2039

Network Working Group C. Kalbfleisch Request for Comments: 2039 OnRamp Technologies, Inc. Category: Informational November 1996

  Applicablity of Standards Track MIBs to Management of World Wide
                            Web Servers

Status of this Memo

 This memo provides information for the Internet community.  This memo
 does not specify an Internet standard of any kind.  Distribution of
 this memo is unlimited.

1. Abstract

 This document was produced at the request of the Network Management
 Area Director following the HTTP-MIB BOF at the 35th IETF meeting to
 report on the applicability of the existing standards track MIBs to
 management of WWW servers.
 Requirements for management of a World Wide Web (WWW) server are
 presented.  The applicable existing standards track MIBs are then
 examined.  Finally, an analysis of the additional groups of MIB
 attributes that are needed to meet the requirements is presented.

Table of Contents

1.     Abstract.................................................1
2.     Overview.................................................2
3.     Requirements.............................................3
3.1    Operational Model Requirements...........................3
3.1.1. Host specific and Application Monitoring.................3
3.1.2. Dependencies among applications..........................3
3.1.3. Error generation and reporting...........................3
3.1.4. Capacity planning........................................4
3.1.5. Log Digester.............................................4
3.2.   Service Model Requirements...............................4
3.2.1. Retrieval services.......................................4
3.2.2. Document information store -- managing documents.........4
3.2.3. Server configuration.....................................4
3.2.4. Server Control...........................................4
3.2.5. Quality of Service.......................................4
4.     Relationship to existing IETF efforts....................5
4.1.   MIB-II [2]...............................................5
4.2.   Host Resources MIB [3]...................................5
4.3.   Network Services Monitoring MIB [4]......................6
4.4.   Application MIB [5]......................................7

Kalbfleisch Informational [Page 1] RFC 2039 WWW Track MIBs November 1996

5.     Summary of Existing Standards Track MIBs.................8
6.     Definition of additional attributes......................9
7.     Usage Scenarios.........................................11
8.     Conclusion..............................................11
9.     References..............................................13
10.    Acknowledgments.........................................13
11.    Further Information.....................................14
12.    Security Considerations.................................14
13.    Authors' Address........................................14

2. Overview

 The World Wide Web (WWW) is a network of information, accessible via
 a simple easy to use interface.  The information is often presented
 in HyperText or multi-media.  The information is provided by servers
 which are located all around the world.  The usability of the web
 depends largely on the performance of these servers. WWW servers are
 typically monitored through log files.  This becomes a difficult task
 when a single organization is responsible for a number of servers.
 Since many organizations currently use the Internet Standard SNMP to
 manage their network devices, it is desirable to treat these WWW
 servers as additional devices within this framework. This will allow
 a single Network Management Station (NMS) to automate the management
 of a number of WWW servers as well as the entire enterprise. Defining
 a standard for this purpose allows a single management application to
 manage a number of servers from a variety of vendors.  Additionally,
 a formal definition of what has to be managed and how to manage it
 tends to lead to integrated and improved performance and fault
 management.
 Content providers are interested in the access statistics and
 configuration of their sites. The content provider may be the same or
 a different organization than the one that maintains the server as a
 whole. It may be possible to realize the new paradigm of "Customer
 Network Management" to provide this information to the content
 provider. This means that there exists a distinct organization
 different than the network operations center that is also interested
 in the management information from a device. Customer network
 management is desirable to allow each content provider on a server to
 access information about his own documents independent of the rest.
 Various organizations may be interested in SNMP manageable WWW
 clients and proxies as well. At this time, our focus is on WWW
 servers. A natural extension to this work could be a framework for
 managing WWW Clients and general information retrieval systems like
 WWW proxies, NNTP, GOPHER, FTP and WAIS.  The focus of this document
 remains the management of WWW servers.

Kalbfleisch Informational [Page 2] RFC 2039 WWW Track MIBs November 1996

3. Requirements

 WWW servers can be viewed from several perspectives when assigning
 management responsibilities.  For the sake of discussion, these
 perspectives are named the Operational Model and the Service Model.
 The Operational Model views WWW servers as computers with hardware,
 disk, OS and web server software.  This model represents the actual
 resources that make up the machine so that it can be monitored from
 the perspective of resource utilization.  The Service Model views the
 WWW server as a black box that simply handles the responses to
 requests from clients located on the web.
 The two models compliment each other while providing distinct
 information about the server.  Members of the organization
 responsible for the WWW server, may be interested in one and/or both
 of the management models.  For this reason, the management
 information should be scalable, for one or both models to be
 implemented independent of the other.
 With this in mind, the requirements for WWW server management can are
 summarized below by expanding upon those generated at the HTTP-MIB
 BOF.

3.1 Operational Model Requirements

3.1.1. Host specific and Application Monitoring

 This includes monitoring the utilization of CPU, disk and network
 capacity.

3.1.2. Dependencies among applications.

 Some systems implement a number of services within a single piece of
 code. Others use multiple pieces of code to implement the same set of
 services. Because of this, dependencies develop among processes.
 These dependencies become critical when a particular process needs to
 be stopped, restarted or reconfigured. These dependencies need to be
 defined within the management information so that management
 applications can operate the systems correctly.

3.1.3. Error generation and reporting

 The WWW server generally reports errors via logging facilities.  The
 format of the log file is not well defined.  It is required that a
 standard facility for error reporting be utilized.

Kalbfleisch Informational [Page 3] RFC 2039 WWW Track MIBs November 1996

3.1.4. Capacity planning

 It is required to obtain statistics which can be used for capacity
 planning purposes. This includes planning for increased network
 bandwidth, computing power, disk space, number of concurrent server
 threads, etc.

3.1.5. Log Digester

 WWW servers generally report status information by data generated in
 Common Log Format [1].  This information needs to be preserved as
 attributes in a MIB to facilitate remote monitoring providing a
 standard way to represent and retrieve the management information.

3.2. Service Model Requirements

3.2.1. Retrieval services

 Retrieval services are an abstract decoupling the information space
 from the underlying transport mechanism.  The goal at this time is to
 focus on the requirements for management of WWW servers. There may be
 considerable overlap with other types of servers like (FTP, NNTP,
 GOPHER and WAIS).  The term "retrieval services" is used here to
 retain this abstraction.  It is required to get statistics about the
 usage and performance of the retrieval services.

3.2.2. Document information store – managing documents.

 Information from a WWW server can be static (a file) or dynamic (the
 output of some processing).  Management of these two types of
 information sources range from maintaining access statistics and
 access permissions to verifying the operational status of all
 applications that provide the dynamic information.

3.2.3. Server configuration.

 It is desirable to be able to centralize configuration management of
 the servers within an enterprise.

3.2.4. Server Control.

 WWW servers generally need to be controlled in regards to starting
 and stopping them as well as rotating log files.

3.2.5. Quality of Service

 Provide an indication of the quality of service the WWW server is
 providing.

Kalbfleisch Informational [Page 4] RFC 2039 WWW Track MIBs November 1996

4. Relationship to existing IETF efforts

 In general, a WWW server is made up of or depends upon the following
 components:
  1. a general purpose workstation running some operating system
  2. http server software to answers requests from the network
  3. various support routines like CGI programs or external

applications (like DBMS) used to access information

  1. a document store on one or more storage devices
 The health and performance of each of the above components is of
 interest when managing a WWW server.
 There are a number of standards track MIB modules that are of
 interest to the above list of items.  This list includes MIB-II [2],
 Host Resources MIB [3], Network Service Monitoring MIB [4] and
 Application MIB [5].
 This creates an impressive list of attributes to be implemented.  A
 definition of various levels of management of a WWW server is desired
 so that the implementor may scale his implementation in chunks which
 may include various components of each section.  For instance, this
 may allow customer network management without requiring the other
 groups being implemented.

4.1. MIB-II [2]

 MIB-II defines the managed objects which should be contained within
 TCP/IP based devices.
 The WWW server should support the applicable portions of MIB-II.
 This set probably includes, as a minimum, the following groups:
 system, interfaces, udp, icmp, tcp and snmp.

4.2. Host Resources MIB [3]

 This MIB defines a uniform set of objects useful for the management
 of host computers independently of the operating system, network
 services, or any software application.
 The MIB is structured as six groups; each specified as either
 "mandatory" or "optional".  If ANY "optional" group of the MIB is
 implemented, then ALL "mandatory" groups of the MIB must also be
 implemented.  This may cause implementation problems for some
 developers since many of these attributes require intimate knowledge
 of the OS.

Kalbfleisch Informational [Page 5] RFC 2039 WWW Track MIBs November 1996

 The groups defined by the MIB are:
  1. System Group Mandatory
  2. Storage Group Mandatory
  3. Device Group Mandatory
  1. device types
  2. device table
  3. processor table
  4. network table
  5. printer table
  6. disk storage table
  7. partition table
  8. file-system table
  9. file-system types
  10. Running Software Group Optional
  11. Running Software Performance Group Optional
  12. Installed Software Group Optional
 The system group provides general status information about the host.
 The storage and device groups define the information about the
 configuration and status of the resources which compose the host.  It
 defines the resources which make up a generic host system and how
 they relate to each other.  Much of this information is useful for
 managing various aspects of a WWW server, like the file system and
 CPU utilization.  This information is useful for meeting the
 operational requirements. Much of this information is however more
 detailed than many WWW server managers require for service level
 requirements.
 The remaining groups define software components which are installed
 and/or running on the host.  Performance information is defined which
 extends that defined for each running process.  Unfortunately, the
 mapping between running software and installed software is difficult
 since it is related by a foreign key (Product ID) which does not
 appear to be required to exist in either table [6]. There is no
 provision to represent a group of processes which together perform
 some task (IE an application made up of multiple processes). The
 Applications MIB WG plans to address these deficiencies.

4.3. Network Services Monitoring MIB [4]

 This MIB is one of three documents produced by the MADMAN (Message
 And Directory MANagement) Working group.  It defines a set of general
 purpose attributes which would be appropriate for a range of
 applications that provide network services.  This definition is from
 the perspective of the service without considering the implementation
 in terms of host computers or processes.  Attributes provide

Kalbfleisch Informational [Page 6] RFC 2039 WWW Track MIBs November 1996

 statistics and status on the in-bound and out-bound associations that
 are currently active, and which have been active.
 This MIB is intended to be the minimum set of attributes common
 across a number of Network Service Applications.  Additional
 attributes are to be defined as necessary to manage specific network
 service applications.  WWW servers clearly fall into the category of
 network service applications.  All attributes in this MIB are
 relevant to WWW servers.
 The MIB consists of two tables:
  1. applTable Mandatory
  2. assocTable Optional
 The applTable describes applications that provide network services
 and keeps statistics of the current number of active associations and
 the total number of associations since application initialization.
 The assocTable contains more detailed information about active
 associations.
 The other two MIBs defined by MADMAN, MTA MIB [7] and DSA MIB [8],
 are not relevant to the management of WWW services.  They do,
 however, demonstrate how to extend the Network Services Monitoring
 MIB for a specific set of applications.

4.4. Application MIB [5]

 The Application MIB WG is defining two separate MIBs: the sysApplMib
 and the applMib.  The first defines attributes that can be monitored
 without instrumenting the applications.  The second will define
 additional attributes requiring application instrumentation.
 The sysApplMIB allows for the description of applications as a
 collection of executables, and files installed and executing on a
 host computer. The objects support configuration, fault and
 performance management of some of the basic attributes of application
 software.

Kalbfleisch Informational [Page 7] RFC 2039 WWW Track MIBs November 1996

 The groups defined in the sysApplMIB are:
  1. System Application Installed Group Mandatory
    1. sysApplInstalledTable
    2. sysApplCfgElmtTable
  1. System Application Run Group Mandatory
    1. sysApplRunTable
    2. SysApplPastRunTable
    3. sysApplElmtRunTable
    4. sysApplElmtPastRunTable
 The sysApplInstalledTable captures what applications are installed on
 a particular host and the sysApplCfgElmtTable provides information
 regarding the executables and non executable files which collectively
 compose the application. The sysApplRunTable contains the application
 instances which are currently running and the sysApplPastRunTable
 contains a history about applications which have previously executed
 on the host. The sysApplElmtRunTable contains the process instances
 which are currently running and sysApplElmtPastRunTable contains a
 history about processes which have previously executed on the host.
 It should be noted that two implementations of the same set of
 network services may each define a different set of processes and
 files within this MIB.  Ultimately enough management information is
 needed so that these different implementations can at least be
 managed similarly.
 WWW servers fall into the general category of application software.
 Therefore the attributes of this MIB are applicable if the process
 level detail is requested to meet the Operational Model requirements.
 The Application MIB WG is to resolve the problems described above
 with the relationship between the running and installed software of
 the Host Resources MIB.

5. Summary of Existing Standards Track MIBs

 The existing MIBs are largely orthogonal as demonstrated by the
 diagram below.  Host Resources relates network information to the
 interfaces defined in MIB-II.  The system application MIB relates its
 running element table to the equivalent entry in the Host Resources
 running software table.
 It should be noted that the running software of the Host Resources
 includes ALL software running on the host, while the running element
 table of the system application MIB only includes "interesting"
 processes of monitored applications.

Kalbfleisch Informational [Page 8] RFC 2039 WWW Track MIBs November 1996

 In the diagram below, "Other Services", "Application Specific MIBs"
 and "Application MIB" represent work to be done or in progress.
                        +---------------+
                        |  Application  |
                        | Specific MIBs |
                        +---------------+
                               |
+--------+ +---+ +---+  +---------------+
|Other   | |MTA| |DSA|  |  Application  |
|services| |MIB| |MIB|  |      MIB      |
+--------+ +---+ +---+  +---------------+
    |        |     |           |
+--------------------+  +---------------+  +--------------+  +------+
|  Network Services  |  |    System     |  |Host Resources|  |MIB-II|
|   Monitoring MIB   |  |Application MIB|--|     MIB      |--|      |
+--------------------+  +---------------+  +--------------+  +------+
 The stack of MIBs above "Network Services Monitoring MIB" represent
 monitoring from the Service Model.  The other stacks represent
 monitoring from the Operational Model.  Neither of these stacks goes
 to the level of specific detail for any application. The author is of
 the opinion that HTTP or Web Server specific MIBs would exist at the
 top of each stack to represent the service and implementation view of
 the server respectively.  There should be a relationship between
 these two perspectives defined so that the correlations between the
 two perspectives is possible.  This relationship would be useful for
 general application and service monitoring in addition to just web
 servers.  However, it is not of specific interest to either the
 MADMAN WG or the Application MIB WG. It is therefore suggested that
 such a relationship is defined in a general case outside of either of
 those groups that would be applicable for WWW servers as well as for
 other application to service mappings.

6. Definition of additional attributes

 The existing MIB attributes meet the Operational Model Requirement
 for tracking information specific to a host.  Specifically, MIB-II,
 Host Resources and the Applications MIB address these items. The
 Network Services MIB addresses a portion of the service model
 requirement for the decoupling of the information space from the
 transport mechanism.
 Several sets of additional attributes are needed to meet the
 remaining requirements. These additional attributes may be generally
 applicable to other network information retrieval services (like FTP,
 NNTP, GOPHER and WAIS) as well as client and proxy management.
 Management of these services is not the scope of this document.

Kalbfleisch Informational [Page 9] RFC 2039 WWW Track MIBs November 1996

 These additional attributes can be classified as:
 1) Definition of relationship between the Network Services Monitoring
    and Application MIBs.  This allows the functional organization of
    the server to be known.  It allows the management application to
    understand the effect of restarting specific processes on the
    services provided.  This addresses the Operational Model
    requirement to model dependencies between applications.
 2) Additions to generic Network Services Monitoring MIB. A draft [9]
    has already been circulated due to the work of a mailing list and
    a sample implementation.  These attributes list a summary at the
    service level of the configuration and the health of the server.
    From this, performance metrics can be observed.  In addition, the
    health of the server in terms of data timeouts is known.  These
    attributes address the requirement for Operational Model tracking
    of specific activity and the requirement for Service Model
    retrieval services.
 3) Document storage and access statistics are needed to address
    service model requirements.
 4) Additions to Application MIB are required to address server
    configuration requirements in the service model.
 5) Error and fault management attributes are required to address
    requirements for tracking specific activity of the web server.
 6) Configuration and Control are items that may be able to be defined
    in a general way within the applications MIB.  If not, a specific
    definition would be required here.
 Of the items listed above, (1) is needed on a general basis.  The
 others appear to the author as WWW server specific unless the scope
 of the work is opened to WWW clients and proxies as well as other
 services (like NNTP, FTP, GOPHER and WAIS).

Kalbfleisch Informational [Page 10] RFC 2039 WWW Track MIBs November 1996

7. Usage Scenarios

 The example scenario will be a single host computer which implements
 WWW services using the "virtual domain" concept.  In this model, a
 single host performs as the WWW server for one or more addresses.
 For the purpose of example, we will specify that there are three
 domains being serviced from this host whose WWW servers are:
 Some implementations may implement these services as one set of
 processes that handle requests for each of the addresses.  Others may
 implement these services as a set of processes for each address.
 This means that the relationship defined between the Network Services
 Monitoring MIB and Application MIB components of the management
 information may vary between different implementations of the same
 configuration.
 MIB-II and Host Resources would provide the information about the
 host including the CPU, disk and network.  The Host Resource running
 table provide information on the processes in the system.
 There would be an entry in the Network Services Monitoring applTable
 for each virtual domain.  In addition, the assocTable shows which
 connections are currently active.  An extension to the association
 table would be helpful to provide information as to what is being
 transmitted.
 The sysApplMib would have entries in its installed software tables
 for the web server software and each "interesting" component.  This
 should include the server binary, CGI programs, configuration files
 and possibly the server log files.  Depending on the implementation
 of the server, the processes for each domain may show up in the same
 or different running software tables.
 Additional information as described in the previous section would
 round out the management information that would be available for the
 WWW server.

8. Conclusion

 A number of currently defined attributes are useful for management of
 a WWW server. Specifically, MIB-II and Host Resources should be
 considered for monitoring the health of the machine in terms of host
 and network configuration and capacity.  The Network Services
 Monitoring MIB and the Application MIBs provide a general framework

Kalbfleisch Informational [Page 11] RFC 2039 WWW Track MIBs November 1996

 to represent the components of the WWW server from both a service and
 implementation perspective.  The Network Services Monitoring MIB
 suggests that extensions are necessary to cover specific network
 application monitoring. A set of such attributes can be well defined
 to provide status information of the WWW server.  The Application MIB
 suggests similar extensions.  Some of these attributes may be generic
 to all applications, and thus be implemented within the scope of the
 applMib. It is the opinion of this author that there will still
 remain specific instrumentation for WWW servers that can not, and
 should not, be covered in the Network Services Monitoring and
 Application MIBs.
 Since the Network Services Monitoring MIB and the Applications MIB
 represent orthogonal efforts of management, it is desirable to define
 the relationship between the two in a standard way.  This definition
 is probably more than a simple pointer from one table to another.
 Since it is outside the scope of either of those efforts, it is this
 author's opinion that that definition could and should be addressed
 within the scope of defining management of a specific application (IE
 WWW servers). This defintion although defined for a particular
 application, should be useful in a general way to describe the
 relationship between the Network Services Monitoring MIB and the
 Applications MIB.
 Additional attributes are needed in order to meet all of the
 requirements specified in this document.  An IETF standard would
 prevent independent developments of this effort in many enterprise
 MIBs.  It also allows management applications to control servers from
 multiple vendors.  It is likely that as the work in this area
 progresses, the management information will be useful for other
 Network Information Retrieval services (like FTP, GOPHER, WAIS and
 NNTP) as well.
 Finally, the Operational Model and Service Model Requirements lead to
 two main uses of the management information.  Design of the MIB
 including the usage of the existing MIBs should allow one or the
 other or both of these models to be implemented in a standard way.
 This may be desirable depending specifically on the audience of the
 data, the cost of instrumentation and the resources of the system.

Kalbfleisch Informational [Page 12] RFC 2039 WWW Track MIBs November 1996

9. References

[1] Anonymous, "Logging in the W3C httpd",

   http://www.w3.org/hypertext/WWW/Daemon/User/Config/Logging.html,
   W3C, July 1995.

[2] McCloghrie, K., and M. Rose, Editors, "Management Information

   Base for Network Management of TCP/IP-based internets: MIB-
   II", STD 17, RFC 1213, Hughes LAN Systems, Performance
   Systems International, March 1991.

[3] Grillo, P., and S. Waldbusser, "Host Resources MIB", RFC 1514,

   Network Innovations, Intel Corporation, Carnegie Mellon
   University, September 1993.

[4] Kille, S., and N. Freed, "Network Services Monitoring MIB",

   RFC 1565, ISODE Consortium, Innosoft, January 1994.

[5] Saperia, J., C. Krupczak, R. Sturm, and J. Weinstock, "Definition

   of Managed Objects for Applications", Work in Progress.

[6] Krupczak, C. and S. Waldbusser, "Applicability of Host Resources

   MIB to Application Management", Empire Technologies, Inc.,
   International Network Services, October 1995.

[7] Kille, S., and N. Freed, "Mail Monitoring MIB", RFC 1566, ISODE

   Consortium, Innosoft, January 1994.

[8] Mansfield, G., and S. Kille, "X.500 Directory Monitoring MIB",

   RFC 1567, AIC Systems Laboratory, ISODE Consortium, January 1994.

[9] Hazewinkel, H., E. van Hengstum, A. Pras, "Definitions of Managed

   Objects for HTTP", Work in Progress.

10. Acknowledgments

 This document was produced at the request of the Network Management
 Area Director following the HTTP-MIB BOF at the 35th IETF meeting to
 report on the applicability of the existing standards track MIBs to
 management of WWW servers.

Kalbfleisch Informational [Page 13] RFC 2039 WWW Track MIBs November 1996

 The author gratefully acknowledges the comments of the following
 individuals:
          Ned Freed, ned@innosoft.com
              Innosoft, Inc.
          Harrie Hazewinkel, hazewink@cs.utwente.nl
              University of Twente
          Cheryl Krupczak, cheryl@empiretech.com
              Empire Technologies, Inc.
          Rui Meneses, rui.meneses@jrc.it
              Centre for Earth Observation
          Jon Saperia, saperia@bgs.com
              BGS Systems, Inc.
          Juergen Schoenwaelder, schoenw@cs.utwente.nl
              University of Twente
          Chris Wellens, chrisw@iwl.com
              InterWorking Labs, Inc.

11. Further Information

 The current status of the HTTP-MIB standardization can be found on
 the World Wide Web at <URL:http://http-mib.onramp.net/>.  An email
 list is in operation for discussion of this topic.  To subscribe,
 send email to "http-mib-request@onramp.net" with the message body of
 "subscribe HTTP-MIB".

12. Security Considerations

 Security issues are not discussed in this memo.

13. Authors' Address

 Carl W. Kalbfleisch
 OnRamp Technologies, Inc.
 Email: cwk@onramp.net
 1950 Stemmons Frwy
 2026 INFOMART
 Dallas, TX 75207, USA               Tel: (214) 672-7246
 cwk@onramp.net                      Fax: (214) 672-7275

Kalbfleisch Informational [Page 14]

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