From 271733ee8eb9a673747bdef320af5ca8e8f18273 Mon Sep 17 00:00:00 2001 From: Guillem Jover Date: Wed, 2 Jul 2014 02:22:32 +0200 Subject: doc: Convert from DebianDoc SGML to DocBook XML --- doc/method.dbk | 712 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 712 insertions(+) create mode 100644 doc/method.dbk (limited to 'doc/method.dbk') diff --git a/doc/method.dbk b/doc/method.dbk new file mode 100644 index 000000000..d2eb04df1 --- /dev/null +++ b/doc/method.dbk @@ -0,0 +1,712 @@ + + + %aptverbatiment; +]> + + + +APT Method Interface + + + + + + Jason Gunthorpejgg@debian.org + + + +Version &apt-product-version; + + + +This document describes the interface that APT uses to the archive access +methods. + + + +1998Jason Gunthorpe + + +License Notice + +"APT" and this document are free software; you can redistribute them and/or +modify them under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2 of the License, or (at your +option) any later version. + + +For more details, on Debian systems, see the file +/usr/share/common-licenses/GPL for the full license. + + + + + +Introduction + +
General + +The APT method interface allows APT to acquire archive files (.deb), index +files (Packages, Release, Mirrors) and source files (.tar.gz, .diff). It is a +general, extensible system designed to satisfy all of these requirements: + + + + +Remote methods that download files from a distant site + + + + +Resume of aborted downloads + + + + +Progress reporting + + + + +If-Modified-Since (IMS) checking for index files + + + + +In-Line MD5 generation + + + + +No-copy in-filesystem methods + + + + +Multi-media methods (like CD's) + + + + +Dynamic source selection for failure recovery + + + + +User interaction for user/password requests and media swaps + + + + +Global configuration + + + + +Initial releases of APT (0.1.x) used a completely different method interface +that only supported the first 6 items. This new interface deals with the +remainder. + +
+ +
Terms + +Several terms are used through out the document, they have specific meanings +which may not be immediately evident. To clarify they are summarized here. + + + +source + + +Refers to an item in source list. More specifically it is the broken down +item, that is each source maps to exactly one index file. Archive sources map +to Package files and Source Code sources map to Source files. + + + + +archive file + + +Refers to a binary package archive (.deb, .rpm, etc). + + + + +source file + + +Refers to one of the files making up the source code of a package. In debian +it is one of .diff.gz, .dsc. or .tar.gz. + + + + +URI + + +Universal Resource Identifier (URI) is a super-set of the familiar URL +syntax used by web browsers. It consists of an access specification +followed by a specific location in that access space. The form is +<access>:<location>. Network addresses are given with the form +<access>://[<user>[:<pas>]@]hostname[:port]/<location>. +Some examples: + + +file:/var/mirrors/debian/ +ftp://ftp.debian.org/debian +ftp://jgg:MooCow@localhost:21/debian +nfs://bigred/var/mirrors/debian +rsync://debian.midco.net/debian +cdrom:Debian 2.0r1 Disk 1/ + + + + +method + + +There is a one to one mapping of URI access specifiers to methods. A method is +a program that knows how to handle a URI access type and operates according to +the specifications in this file. + + + + +method instance + + +A specific running method. There can be more than one instance of each method +as APT is capable of concurrent method handling. + + + + +message + + +A series of lines terminated by a blank line sent down one of the communication +lines. The first line should have the form xxx TAG where xxx are digits +forming the status code and TAG is an informational string + + + + +acquire + + +The act of bring a URI into the local pathname space. This may simply be +verifying the existence of the URI or actually downloading it from a remote +site. + + + + +
+ + + +Specification + +
Overview + +All methods operate as a sub process of a main controlling parent. 3 FD's are +opened for use by the method allowing two way communication and emergency error +reporting. The FD's correspond to the well known unix FD's, stdin, stdout and +stderr. + + +Through operation of the method communication is done via http style plain +text. Specifically RFC-822 (like the Package file) fields are used to describe +items and a numeric-like header is used to indicate what is happening. Each of +these distinct communication messages should be sent quickly and without pause. + + +In some instances APT may pre-invoke a method to allow things like file URI's +to determine how many files are available locally. + +
+ +
Message Overview + +The first line of each message is called the message header. The first 3 +digits (called the Status Code) have the usual meaning found in the http +protocol. 1xx is informational, 2xx is successful and 4xx is failure. The 6xx +series is used to specify things sent to the method. After the status code is +an informational string provided for visual debugging. + + + + +100 Capabilities - Method capabilities + + + + +101 Log - General Logging + + + + +102 Status - Inter-URI status reporting (login progress) + + + + +200 URI Start - URI is starting acquire + + + + +201 URI Done - URI is finished acquire + + + + +400 URI Failure - URI has failed to acquire + + + + +401 General Failure - Method did not like something sent to it + + + + +402 Authorization Required - Method requires authorization to access the URI. +Authorization is User/Pass + + + + +403 Media Failure - Method requires a media change + + + + +600 URI Acquire - Request a URI be acquired + + + + +601 Configuration - Sends the configuration space + + + + +602 Authorization Credentials - Response to the 402 message + + + + +603 Media Changed - Response to the 403 message + + + + +Only the 6xx series of status codes is sent TO the method. Furthermore the +method may not emit status codes in the 6xx range. The Codes 402 and 403 +require that the method continue reading all other 6xx codes until the proper +602/603 code is received. This means the method must be capable of handling an +unlimited number of 600 messages. + + +The flow of messages starts with the method sending out a 100 +Capabilities and APT sending out a 601 +Configuration. After that APT begins sending 600 URI +Acquire and the method sends out 200 URI Start, +201 URI Done or 400 URI Failure. No +synchronization is performed, it is expected that APT will send 600 +URI Acquire messages at -any- time and that the method should queue +the messages. This allows methods like http to pipeline requests to the remote +server. It should be noted however that APT will buffer messages so it is not +necessary for the method to be constantly ready to receive them. + +
+ +
Header Fields + +The following is a short index of the header fields that are supported + + + +URI + + +URI being described by the message + + + + +Filename + + +Location in the filesystem + + + + +Last-Modified + + +A time stamp in RFC1123 notation for use by IMS checks + + + + +IMS-Hit + + +The already existing item is valid + + + + +Size + + +Size of the file in bytes + + + + +Resume-Point + + +Location that transfer was started + + + + +MD5-Hash + + +Computed MD5 hash for the file + + + + +Message + + +String indicating some displayable message + + + + +Media + + +String indicating the media name required + + + + +Site + + +String indicating the site authorization is required for + + + + +User + + +Username for authorization + + + + +Password + + +Password for authorization + + + + +Fail + + +Operation failed + + + + +Drive + + +Drive the media should be placed in + + + + +Config-Item + + +A string of the form +item=value derived from +the APT configuration space. These may include method specific values and +general values not related to the method. It is up to the method to filter out +the ones it wants. + + + + +Single-Instance + + +Requires that only one instance of the method be run This is a yes/no value. + + + + +Pipeline + + +The method is capable of pipelining. + + + + +Local + + +The method only returns Filename: fields. + + + + +Send-Config + + +Send configuration to the method. + + + + +Needs-Cleanup + + +The process is kept around while the files it returned are being used. This is +primarily intended for CD-ROM and File URIs that need to unmount filesystems. + + + + +Version + + +Version string for the method + + + + + +This is a list of which headers each status code can use + + + +100 Capabilities + + +Displays the capabilities of the method. Methods should set the pipeline bit +if their underlying protocol supports pipelining. The only known method that +does support pipelining is http. Fields: Version, Single-Instance, Pre-Scan, +Pipeline, Send-Config, Needs-Cleanup + + + + +101 Log + + +A log message may be printed to the screen if debugging is enabled. This is +only for debugging the method. Fields: Message + + + + +102 Status + + +Message gives a progress indication for the method. It can be used to show +pre-transfer status for Internet type methods. Fields: Message + + + + +200 URI Start + + +Indicates the URI is starting to be transferred. The URI is specified along +with stats about the file itself. Fields: URI, Size, Last-Modified, +Resume-Point + + + + +201 URI Done + + +Indicates that a URI has completed being transferred. It is possible to +specify a 201 URI Done without a URI +Start which would mean no data was transferred but the file is now +available. A Filename field is specified when the URI is directly available in +the local pathname space. APT will either directly use that file or copy it +into another location. It is possible to return Alt-* fields to indicate that +another possibility for the URI has been found in the local pathname space. +This is done if a decompressed version of a .gz file is found. Fields: URI, +Size, Last-Modified, Filename, MD5-Hash + + + + +400 URI Failure + + +Indicates a fatal URI failure. The URI is not retrievable from this source. As +with 201 URI Done 200 URI Start is +not required to precede this message Fields: URI, Message + + + + +401 General Failure + + +Indicates that some unspecific failure has occurred and the method is unable +to continue. The method should terminate after sending this message. It +is intended to check for invalid configuration options or other severe +conditions. Fields: Message + + + + +402 Authorization Required + + +The method requires a Username and Password pair to continue. After sending +this message the method will expect APT to send a 602 Authorization +Credentials message with the required information. It is possible +for a method to send this multiple times. Fields: Site + + + + +403 Media Failure + + +A method that deals with multiple media requires that a new media be +inserted. The Media field contains the name of the media to be +inserted. Fields: Media, Drive + + + + +600 URI Acquire + + +APT is requesting that a new URI be added to the acquire list. Last-Modified +has the time stamp of the currently cache file if applicable. Filename is the +name of the file that the acquired URI should be written to. Fields: URI, +Filename Last-Modified + + + + +601 Configuration + + +APT is sending the configuration space to the method. A series of Config-Item +fields will be part of this message, each containing an entry from the +configuration space. Fields: Config-Item. + + + + +602 Authorization Credentials + + +This is sent in response to a 402 Authorization Required +message. It contains the entered username and password. Fields: Site, User, +Password + + + + +603 Media Changed + + +This is sent in response to a 403 Media Failure +message. It indicates that the user has changed media and it is safe +to proceed. Fields: Media, Fail + + + + +
+ +
Notes + +The methods supplied by the stock apt are: + + + + +cdrom - For Multi-Disc CD-ROMs + + + + +copy - (internal) For copying files around the filesystem + + + + +file - For local files + + + + +gzip - (internal) For decompression + + + + +http - For HTTP servers + + + + +The two internal methods, copy and gzip, are used by the acquire code to +parallize and simplify the automatic decompression of package files as well as +copying package files around the file system. Both methods can be seen to act +the same except that one decompresses on the fly. APT uses them by generating +a copy URI that is formed identically to a file URI. The destination file is +send as normal. The method then takes the file specified by the URI and writes +it to the destination file. A typical set of operations may be: + + +http://foo.com/Packages.gz -> /bar/Packages.gz +gzip:/bar/Packages.gz -> /bar/Packages.decomp +rename Packages.decomp to /final/Packages + + +The http method implements a fully featured HTTP/1.1 client that supports +deep pipelining and reget. It works best when coupled with an apache 1.3 +server. The file method simply generates failures or success responses +with the filename field set to the proper location. The cdrom method acts +the same except that it checks that the mount point has a valid cdrom in +it. It does this by (effectively) computing a md5 hash of 'ls -l' on the +mountpoint. + +
+ + + + -- cgit v1.2.3 From 5abbf5bbb5ee8717f89cac6ef409c4cec79259f6 Mon Sep 17 00:00:00 2001 From: David Kalnischkies Date: Fri, 18 Jul 2014 16:42:40 +0200 Subject: ensure that all docs use all entities files Not all are needed for all files at the moment, but the new docbook building hadn't available some of the entities it used as the files weren't correctly copied around in all cases and having the same across the bord makes working with all of them a little easier. Git-Dch: Ignore --- doc/method.dbk | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'doc/method.dbk') diff --git a/doc/method.dbk b/doc/method.dbk index d2eb04df1..09ef63e8c 100644 --- a/doc/method.dbk +++ b/doc/method.dbk @@ -1,8 +1,9 @@ - %aptent; %aptverbatiment; + %aptvendor; ]> -- cgit v1.2.3