Unix System Administration Handbook 1997 October/usah_oct97.iso/rfc/2000s/rfc2039.txt

Text File | 1996-11-04 | 32KB | 788 lines

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



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  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.




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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.






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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.



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4. Relationship to existing IETF efforts

   In general, a WWW server is made up of or depends upon the following
   components:

      -a general purpose workstation running some operating system
      -http server software to answers requests from the network
      -various support routines like CGI programs or external
       applications (like DBMS) used to access information
      -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.




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   The groups defined by the MIB are:

      -System Group                           Mandatory
      -Storage Group                          Mandatory
      -Device Group                           Mandatory

                -device types
                -device table
                -processor table
                -network table
                -printer table
                -disk storage table
                -partition table
                -file-system table
                -file-system types
      -Running Software Group                 Optional
      -Running Software Performance Group     Optional
      -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



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   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:

           -applTable                  Mandatory
           -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.













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   The groups defined in the sysApplMIB are:

           -System Application Installed Group     Mandatory
                   -sysApplInstalledTable
                   -sysApplCfgElmtTable

           -System Application Run Group           Mandatory
                   -sysApplRunTable
                   -SysApplPastRunTable
                   -sysApplElmtRunTable
                   -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.



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   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.



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   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).















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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:

           -www.a.com
           -www.b.com
           -www.c.com

   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



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   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.












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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.











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   The author gratefully acknowledges the comments of the following
   individuals:

            Ned Freed, [e-mail]
                Innosoft, Inc.

            Harrie Hazewinkel, [e-mail]
                University of Twente

            Cheryl Krupczak, [e-mail]
                Empire Technologies, Inc.

            Rui Meneses, [e-mail]
                Centre for Earth Observation

            Jon Saperia, [e-mail]
                BGS Systems, Inc.

            Juergen Schoenwaelder, [e-mail]
                University of Twente

            Chris Wellens, [e-mail]
                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 "[e-mail]" 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: [e-mail]
   1950 Stemmons Frwy
   2026 INFOMART
   Dallas, TX 75207, USA               Tel: [phone]
   [e-mail]                      Fax: [phone]






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