RFC 2244 (rfc2244) - Page 1 of 68


ACAP -- Application Configuration Access Protocol



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Network Working Group                                          C. Newman
Request for Comments: 2244                                      Innosoft
Category: Standards Track                                    J. G. Myers
                                                                Netscape
                                                           November 1997


           ACAP -- Application Configuration Access Protocol


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 1997.  All Rights Reserved.

Abstract

   The Application Configuration Access Protocol (ACAP) is designed to
   support remote storage and access of program option, configuration
   and preference information.  The data store model is designed to
   allow a client relatively simple access to interesting data, to allow
   new information to be easily added without server re-configuration,
   and to promote the use of both standardized data and custom or
   proprietary data.  Key features include "inheritance" which can be
   used to manage default values for configuration settings and access
   control lists which allow interesting personal information to be
   shared and group information to be restricted.

















Newman & Myers              Standards Track                     [Page i]

RFC 2244                          ACAP                     November 1997





                           Table of Contents



Status of this Memo ...............................................    i
Copyright Notice ..................................................    i
Abstract ..........................................................    i
ACAP Protocol Specification .......................................    1
1.       Introduction .............................................    1
1.1.     Conventions Used in this Document ........................    1
1.2.     ACAP Data Model ..........................................    1
1.3.     ACAP Design Goals ........................................    1
1.4.     Validation ...............................................    2
1.5.     Definitions ..............................................    2
1.6.     ACAP Command Overview ....................................    4
2.       Protocol Framework .......................................    4
2.1.     Link Level ...............................................    4
2.2.     Commands and Responses ...................................    4
2.2.1.   Client Protocol Sender and Server Protocol Receiver ......    4
2.2.2.   Server Protocol Sender and Client Protocol Receiver ......    5
2.3.     Server States ............................................    6
2.3.1.   Non-Authenticated State ..................................    6
2.3.2.   Authenticated State ......................................    6
2.3.3.   Logout State .............................................    6
2.4.     Operational Considerations ...............................    7
2.4.1.   Untagged Status Updates ..................................    7
2.4.2.   Response when No Command in Progress .....................    7
2.4.3.   Auto-logout Timer ........................................    7
2.4.4.   Multiple Commands in Progress ............................    8
2.5.     Server Command Continuation Request ......................    8
2.6.     Data Formats .............................................    8
2.6.1.   Atom .....................................................    9
2.6.2.   Number ...................................................    9
2.6.3.   String ...................................................    9
2.6.3.1. 8-bit and Binary Strings .................................   10
2.6.4.   Parenthesized List .......................................   10
2.6.5.   NIL ......................................................   10
3.       Protocol Elements ........................................   10
3.1.     Entries and Attributes ...................................   10
3.1.1.   Predefined Attributes ....................................   11
3.1.2.   Attribute Metadata .......................................   12
3.2.     ACAP URL scheme ..........................................   13
3.2.1.   ACAP URL User Name and Authentication Mechanism ..........   13
3.2.2.   Relative ACAP URLs .......................................   14
3.3.     Contexts .................................................   14



Newman & Myers              Standards Track                    [Page ii]

RFC 2244                          ACAP                     November 1997


3.4.     Comparators ..............................................   15
3.5.     Access Control Lists (ACLs) ..............................   17
3.6.     Server Response Codes ....................................   18
4.       Namespace Conventions ....................................   21
4.1.     Dataset Namespace ........................................   21
4.2.     Attribute Namespace ......................................   21
4.3.     Formal Syntax for Dataset and Attribute Namespace ........   22
5.       Dataset Management .......................................   23
5.1.     Dataset Inheritance ......................................   23
5.2.     Dataset Attributes .......................................   24
5.3.     Dataset Creation .........................................   25
5.4.     Dataset Class Capabilities ...............................   25
5.5.     Dataset Quotas ...........................................   26
6.       Command and Response Specifications ......................   26
6.1.     Initial Connection .......................................   26
6.1.1.   ACAP Untagged Response ...................................   26
6.2.     Any State ................................................   27
6.2.1.   NOOP Command .............................................   27
6.2.2.   LANG Command .............................................   28
6.2.3.   LANG Intermediate Response ...............................   28
6.2.4.   LOGOUT Command ...........................................   29
6.2.5.   OK Response ..............................................   29
6.2.6.   NO Response ..............................................   29
6.2.7.   BAD Response .............................................   30
6.2.8.   BYE Untagged Response ....................................   30
6.2.9.   ALERT Untagged Response ..................................   31
6.3.     Non-Authenticated State ..................................   31
6.3.1.   AUTHENTICATE Command .....................................   31
6.4.     Searching ................................................   33
6.4.1.   SEARCH Command ...........................................   33
6.4.2.   ENTRY Intermediate Response ..............................   37
6.4.3.   MODTIME Intermediate Response ............................   38
6.4.4.   REFER Intermediate Response ..............................   38
6.4.5.   Search Examples ..........................................   38
6.5.     Contexts .................................................   39
6.5.1.   FREECONTEXT Command ......................................   39
6.5.2.   UPDATECONTEXT Command ....................................   40
6.5.3.   ADDTO Untagged Response ..................................   40
6.5.4.   REMOVEFROM Untagged Response .............................   41
6.5.5.   CHANGE Untagged Response .................................   41
6.5.6.   MODTIME Untagged Response ................................   42
6.6.     Dataset modification .....................................   42
6.6.1.   STORE Command ............................................   42
6.6.2.   DELETEDSINCE Command .....................................   45
6.6.3.   DELETED Intermediate Response ............................   45
6.7.     Access Control List Commands .............................   45
6.7.1.   SETACL Command ...........................................   46
6.7.2.   DELETEACL Command ........................................   46



Newman & Myers              Standards Track                   [Page iii]

RFC 2244                          ACAP                     November 1997


6.7.3.   MYRIGHTS Command .........................................   47
6.7.4.   MYRIGHTS Intermediate Response ...........................   47
6.7.5.   LISTRIGHTS Command .......................................   47
6.7.6.   LISTRIGHTS Intermediate Response .........................   48
6.8.     Quotas ...................................................   48
6.8.1.   GETQUOTA Command .........................................   48
6.8.3.   QUOTA Untagged Response ..................................   49
6.9.     Extensions ...............................................   49
7.       Registration Procedures ..................................   49
7.1.     ACAP Capabilities ........................................   50
7.2.     ACAP Response Codes ......................................   50
7.3.     Dataset Classes ..........................................   51
7.4.     Vendor Subtree ...........................................   51
8.       Formal Syntax ............................................   52
9.       Multi-lingual Considerations .............................   61
10.      Security Considerations ..................................   62
11.      Acknowledgments ..........................................   63
12.      Authors' Addresses .......................................   63
Appendices ........................................................   64
A.       References ...............................................   64
B.       ACAP Keyword Index .......................................   66
C.       Full Copyright Statement





























Newman & Myers              Standards Track                    [Page iv]
RFC 2244                          ACAP                     November 1997


ACAP Protocol Specification

1.       Introduction

1.1.     Conventions Used in this Document

   In examples, "C:" and "S:" indicate lines sent by the client and
   server respectively.  If such lines are wrapped without a new "C:" or
   "S:" label, then the wrapping is for editorial clarity and is not
   part of the command.

   The key words "REQUIRED", "MUST", "MUST NOT", "SHOULD", "SHOULD NOT",
   and "MAY" in this document are to be interpreted as described in "Key
   words for use in RFCs to Indicate Requirement Levels" [KEYWORDS].

1.2.     ACAP Data Model

   An ACAP server exports a hierarchical tree of entries.  Each level of
   the tree is called a dataset, and each dataset is made up of a list
   of entries.  Each entry has a unique name and may contain any number
   of named attributes.  Each attribute within an entry may be single
   valued or multi-valued and may have associated metadata to assist
   access and interpretation of the value.

   The rules with which a client interprets the data within a portion of
   ACAP's tree of entries are called a dataset class.

1.3.     ACAP Design Goals

   ACAP's primary purpose is to allow users access to their
   configuration data from multiple network-connected computers.  Users
   can then sit down in front of any network-connected computer, run any
   ACAP-enabled application and have access to their own configuration
   data.  Because it is hoped that many applications will become ACAP-
   enabled, client simplicity was preferred to server or protocol
   simplicity whenever reasonable.

   ACAP is designed to be easily manageable.  For this reason, it
   includes "inheritance" which allows one dataset to inherit default
   attributes from another dataset.  In addition, access control lists
   are included to permit delegation of management and quotas are
   included to control storage.  Finally, an ACAP server which is
   conformant to this base specification should be able to support most
   dataset classes defined in the future without requiring a server
   reconfiguration or upgrade.






Newman & Myers              Standards Track


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