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AFP Reference

Thu, 13 Dec 2012 00:00:00 +0000

AFP Reference#

Overview#

This document describes the Apple Filing Protocol (AFP) commands, data types and constants that can be used to communicate with an AFP file server. AFP allows users of multiple computers to share files easily and efficiently over a network.

In this protocol reference, references to a string type indicate a Pascal string. The first byte of a Pascal string indicates the string length (0-255), and is followed by up to 255 bytes of text. Pascal strings are not null-terminated.

Introduction

Thu, 13 Dec 2012 00:00:00 +0000

Introduction#

The Apple Filing Protocol (AFP) allows users of multiple computers to share files easily and efficiently over a network.

This document describes the AFP wire protocol at a conceptual level. For detailed information about the request blocks that an AFP client sends to an AFP server and the reply blocks that an AFP server sends to an AFP client in response to a request block, see Apple Filing Protocol Reference.

AFP Concepts

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AFP Concepts#

File Access Model#

This section introduces the file access model used by AFP to enable file sharing and discusses the components of AFP software.

Note: All values exchanged between an AFP client and an AFP server are sent over the network in network byte order.

Figure 1-1 AFP file access model

A program running in a local computer requests and manipulates files by using that computer’s native file system commands. These commands manipulate files on disk or other memory resource that is physically connected to the local computer. Through AFP, a program can use the same native file system commands to manipulate files on a shared resource that resides on a remote computer (for example, a file server).

AFP Character Encoding

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AFP Character Encoding#

If the server and the sharepoint support UTF-8 names, the AFP server and client send and receive decomposed UTF-8. However, characters in the range of U2000 to U2FFF, UFE30 to UFE4F, and U2F800 to U2FA1F are not decomposed. For complex characters, Unicode 3.2-based tables are used. For additional information, see http://developer.apple.com/technotes/tn/tn1150.html#UnicodeSubtleties and the Unicode specifications.

For Macintosh Roman, AFP utilizes character string entity names that can be composed of any 8-bit character. Character representations are exactly the same as those used by the Mac OS and are shown in Figure 2-1.

AFP File Server Security

Thu, 13 Dec 2012 00:00:00 +0000

AFP File Server Security#

Information stored in a shared resource needs protection from unauthorized users. The role of file server security is to provide varying amounts and kinds of protection, depending on what users feel is necessary.

AFP provides security in three ways:

user authentication when the user logs in to the server
an optional volume-level password when the user first attempts to gain access to a volume
directory access controls

File Sharing Modes

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AFP controls user access to shared files in two ways. The first, described in AFP File Server Security, provides security by controlling user access to specific directories. The second, described in this section, preserves data integrity by controlling a user’s access to a file while it is being used by another user.

To control simultaneous file access, the file server must enforce synchronization rules. These rules prevent applications from damaging each other’s files by modifying the same version simultaneously. These rules also prevent users from obtaining access to information while it is being changed.

Using Login Commands

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An AFP client uses the following commands to get information about a file server and to open and close a session with it:

FPGetSrvrInfo
FPGetAuthMethods (deprecated)
FPLogin and FPLoginExt
FPLoginCont
FPGetSrvrParms
FPGetSessionToken
FPDisconnectOldSession
FPLogout
FPMapID
FPMapName
FPChangePassword
FPGetUserInfo

The AFP client sends the FPGetSrvrInfo command to obtain server information. The FPGetSrvrInfo command returns server information including the following server parameters: server name, machine type, AFP version strings, UAM strings, volume icon and mask, a bitmap of flags, and optionally, a list of available Open Directory names. For descriptions of server parameters, see FPGetSrvrInfo in the Reference section.

AFP Over TCP

Thu, 13 Dec 2012 00:00:00 +0000

AFP Over TCP#

This chapter describes how the Transmission Control Protocol (TCP) can be used to transport AFP packets efficiently. With TCP as the transport protocol, AFP services can be made available over the Internet just as they are made over AppleTalk networks. When a user mounts a remote volume over TCP, the type of network over which the volume is mounted is completely transparent to the user. On local area networks, providing AFP services over TCP/IP effectively utilizes the bandwidth of high speed network media such as Fiber Distributed Data Interface (FDDI) and Asynchronous Transfer Mode (ATM).

AFP Replay Cache

Thu, 13 Dec 2012 00:00:00 +0000

AFP Replay Cache#

If the server supports the replay cache, then in the DSIOpenSession reply packet from the server, there is a new option type of kServerReplayCacheSize. The Option field length is 4 bytes, and the Option value is the maximum number of DSI requests that the AFP server can cache in its replay cache. The client selects the smaller of its own maximum size or the server’s maximum size.

AFP Client Caching

Thu, 13 Dec 2012 00:00:00 +0000

AFP Client Caching#

This chapter describes how the AFP client in OS X v.10.2 and later caches data before sending it to an AFP server.

First, some terms and definitions:

Universal Buffer Cache (UBC)—A page cache that includes file data caching, memory-mapped I/O backing, and so on. The buffer cache is said to be unified because it exists as part of the normal virtual memory physical page pool rather than as a separately managed buffer.

Using Volume Commands

Thu, 13 Dec 2012 00:00:00 +0000

Using Volume Commands#

AFP provides the following volume-level commands:

FPOpenVol
FPCloseVol
FPGetVolParms
FPSetVolParms
FPFlush
FPCatSearch and FPCatSearchExt

After obtaining the volume names through the FPGetSrvrParms command, the AFP client sends an FPOpenVol command for each volume to which it wants to gain access. If a volume has a password, it must be supplied at this time. The command returns the requested volume parameters, including the volume identifier, VolumeID.

The volume identifier is used in all subsequent commands to identify the volume for which the commands apply and remains valid until the session is terminated by calling FPLogout or the volume is closed by calling FPVolClose.

Using Directory Commands

Thu, 13 Dec 2012 00:00:00 +0000

Using Directory Commands#

AFP provides these commands for working on directories:

FPSetDirParms
FPOpenDir (deprecated)
FPCloseDir (deprecated)
FPEnumerate, FPEnumerateExt, and FPEnumerateExt2
FPCreateDir

The FPSetDirParms command allows the AFP client to modify a directory’s parameters. To obtain a directory’s parameters from the file server, the AFP client uses the FPGetFileDirParms command, which is described in the section Using Combined Directory and File Commands.

On variable Directory ID volumes, the AFP client uses the FPOpenDir command to open a directory on and retrieve its Directory ID. The Directory ID is used in subsequent commands to enumerate the directory or to obtain access to its offspring. For variable Directory ID volumes, the FPOpenDir command is the only way to retrieve the Directory ID. Calling FPGetFileDirParms, FPEnumerate, FPEnumerateExt, or FPEnumerateExt2 to retrieve the Directory ID on such volumes causes an error to be returned.

Using File Commands

Thu, 13 Dec 2012 00:00:00 +0000

Using File Commands#

AFP provides these commands for working on files:

FPSetFileDirParms
FPCreateFile
FPCopyFile
FPCreateID (deprecated)
FPDeleteID (deprecated)
FPResolveID
FPExchangeFiles

The AFP client uses the FPSetFileParms command to modify a specified file’s parameters, the FPCreateFile command to create a file, and the FPCopyFile command to copy a file that exists on a volume managed by a server to any other volume managed by that server. To obtain a specified file’s parameters, the AFP client uses the FPGetFileDirParms command, discussed in the next section.

Using Combined Directory and File Commands

Thu, 13 Dec 2012 00:00:00 +0000

Using Combined Directory and File Commands#

AFP provides five commands that operate on both files and directories:

FPGetFileDirParms
FPSetFileDirParms
FPRename
FPDelete
FPMoveAndRename

The AFP client uses the FPGetFileDirParms command to retrieve the parameters associated with a given file or directory. When it uses this command, the AFP client does not need specify whether the CNode is a file or directory; the file server indicates the CNode’s type in response to this command.

Using Fork Commands

Thu, 13 Dec 2012 00:00:00 +0000

Using Fork Commands#

AFP provides these fork-level commands:

FPGetForkParms
FPSetForkParms
FPOpenFork
FPRead and FPReadExt
FPWrite and FPWriteExt
FPFlushFork
FPByteRangeLock and FPByteRangeLockExt
FPCloseFork

The AFP client uses the FPGetForkParms command to read a fork’s parameters.

The FPSetForkParms command is used to modify a fork’s parameters.

The FPOpenFork command is used to open either fork of an existing file. This command returns an open fork reference number, which is used in subsequent commands for this open fork.

Using Desktop Database Commands

Thu, 13 Dec 2012 00:00:00 +0000

Using Desktop Database Commands#

Note: The Desktop database is no longer supported beginning in OS X v.10.6.

An AFP client uses the following commands to read and write information stored in the server’s Desktop database:

FPOpenDT
FPCloseDT
FPAddIcon
FPGetIcon
FPGetIconInfo
FPAddAPPL
FPRemoveAPPL
FPGetAPPL
FPAddComment
FPRemoveComment
FPGetComment

Before any other Desktop database commands can be sent, the AFP client must send an FPOpenDT command. This command returns a reference number to be used in all subsequent commands on the Desktop database.

AFP Version Differences

Thu, 13 Dec 2012 00:00:00 +0000

AFP Version Differences#

This document as a whole describes the current version of the Apple Filing Protocol. This section provides a list of what commands were added in each AFP version.

For a complete description of the commands themselves, see Apple Filing Protocol Reference.

Missing AFP Command Codes#

12 and 13 were missing from Inside AppleTalk and have never been allocated.

38-43 were missing from Inside AppleTalk but were added in AFP 2.1; presumably they were preallocated for System 7.0.

Document Revision History

Thu, 13 Dec 2012 00:00:00 +0000

Document Revision History#

This table describes the changes to Apple Filing Protocol Programming Guide.

Date	Notes
2012-12-13	Added information about AFP 3.4.
2011-04-18	Clarified explanation of UTF-8 path lengths.
2010-11-15	Corrected errors in the Reconnect UAM explanation and the access mode/deny mode table.
2009-08-20	Updated to cover the Time Machine and case sensitivity flags supported in OS X v.10.6 and AFP protocol version 3.3 and later.
2006-04-04	Moved reference documentation to become a seperate document.
2005-06-04	Fixed idle timer information.
2005-05-12	Updated for AFP version 3.2.

Docs on AFP Docs Mirror

AFP Reference

AFP Reference#

Overview#

Introduction

Introduction#

AFP Concepts

AFP Concepts#

File Access Model#

AFP Character Encoding

AFP Character Encoding#

AFP File Server Security

AFP File Server Security#

File Sharing Modes

File Sharing Modes#

Using Login Commands

Using Login Commands#

AFP Over TCP

AFP Over TCP#

AFP Replay Cache

AFP Replay Cache#

AFP Client Caching

AFP Client Caching#

Using Volume Commands

Using Volume Commands#

Using Directory Commands

Using Directory Commands#

Using File Commands

Using File Commands#

Using Combined Directory and File Commands

Using Combined Directory and File Commands#

Using Fork Commands

Using Fork Commands#

Using Desktop Database Commands

Using Desktop Database Commands#

AFP Version Differences

AFP Version Differences#

Missing AFP Command Codes#

Document Revision History

Document Revision History#