Server/Application State Protocol v1
RFC 4678

Document Type RFC - Informational (September 2006; Errata)
Last updated 2015-10-14
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Network Working Group                                          A. Bivens
Request for Comments: 4678                                  IBM Research
Category: Informational                                   September 2006

                  Server/Application State Protocol v1

Status of This Memo

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

Copyright Notice

   Copyright (C) The Internet Society (2006).

IESG Note

   This RFC is not a candidate for any level of Internet Standard.  The
   IETF disclaims any knowledge of the fitness of this RFC for any
   purpose and in particular notes that the decision to publish is not
   based on IETF review for such things as security, congestion control,
   or inappropriate interaction with deployed protocols.  The RFC Editor
   has chosen to publish this document at its discretion.  Readers of
   this document should exercise caution in evaluating its value for
   implementation and deployment.  See RFC 3932 for more information.

Abstract

   Entities responsible for distributing work across a group of systems
   traditionally do not know a great deal about the ability of the
   applications on those systems to complete the work in a satisfactory
   fashion.  Workload management systems traditionally know a great deal
   about the health of applications, but have little control over the
   rate in which these applications receive work.  The
   Server/Application State Protocol (SASP) provides a mechanism for
   load balancers and workload management systems to communicate better
   ways of distributing the existing workload to the group members.

Bivens                       Informational                      [Page 1]
RFC 4678                         SASPv1                   September 2006

Table of Contents

   1. Introduction ....................................................3
      1.1. Overview ...................................................3
      1.2. Identities .................................................4
   2. Requirements Notation ...........................................4
   3. Conventions Used in This Document ...............................4
   4. General Message Structure .......................................4
      4.1. TLV Structure ..............................................6
      4.2. Component Types ............................................6
      4.3. SASP Protocol Header .......................................7
      4.4. Version Negotiation ........................................8
   5. Singular Protocol Components ....................................9
      5.1. Member Data Component ......................................9
      5.2. Group Data Component ......................................11
      5.3. Weight Entry Data Component ...............................12
      5.4. Member State Instance Component ...........................14
   6. Group Protocol Components ......................................15
      6.1. Group of Member Data Component ............................15
      6.2. Group of Weight Data Component ............................16
      6.3. Group of Member State Data Components .....................17
   7. Protocol Messages ..............................................17
      7.1. Registration Request and Reply ............................18
           7.1.1. Registration Request ...............................18
           7.1.2. Registration Reply .................................19
      7.2. DeRegistration Request and Reply ..........................20
           7.2.1. DeRegistration Request .............................21
           7.2.2. DeRegistration Reply ...............................22
      7.3. Get Weights Request and Reply .............................23
           7.3.1. Get Weights Request ................................24
           7.3.2. Get Weights Reply ..................................25
      7.4. Send Weights ..............................................26
      7.5. Set Member State Request and Reply ........................27
           7.5.1. Set Member State Request ...........................28
           7.5.2. Set Member State Reply .............................29
      7.6. Set Load Balancer State Request and Reply .................30
           7.6.1. Set LB State Request ...............................30
           7.6.2. Set LB State Reply .................................32
   8. Example of SASP Message Encoding ...............................32
   9. Protocol Flow ..................................................37
      9.1. Normal Protocol Flow ......................................37
      9.2. Behavior in Error Cases ...................................39
      9.3. Example Flow 1: Load Balancer Registration,
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