-Like dselect, APT will support plugable acquisition methods to complement
-its internaly supported methods. The files in
-this directory are execultables named after the URI type. APT will
-sort the required URIs and spawn these programs giving a full sorted, quoted
-list of URIs.
-
-<p>
-The interface is simple, the program will be given a list
-of URIs on the command line. The URIs will be in pairs, the first
-being the actual URI and the second being the filename to write the data to.
-The current directory will be set properly by APT and it is
-expected the method will put files relative to the current directory.
-The output of these programs is strictly speficied. The programs must accept
-nothing from stdin (stdin will be an invalid fd) and they must output
-status information to stdout according to the format below.
-Stderr will be redirected to the logging facility.
-
-<p>
-Each line sent to stdout must be a line that has a single letter and a
-space. Strings after the first letter do not need quoting, they are taken
-as is till the end of the line. The tag letters, listed in expected order,
-is as follows:
-
-<taglist>
-
-<tag>F - Change URI<item>
-This specifies a change in URI. All information after this will be applied
-to the new URI. When the URI is changed it is assumed that the old URI has
-completed unless an error is set. The format is <var>F URI</>
-
-<tag>S - Object Size<item>
-This specifies the expected size of the object. APT will use this to
-compute percent done figures. If it is not sent then a kilobyte meter
-will be used instead of a percent display. The foramat is <var>S INTEGER</>
-
-<tag>E - Error Information<item>
-Exactly one line of error information can be set for each URI. The
-information will be summarized for the user. If an E tag is send before
-any F tags then the error is assumed to be a fatal method error and all URI
-fetches for that method are aborted with that error string. The format
-is <var>E String</>
-
-<tag>I - Informative progress information<item>
-The I tag allows the method to specify the status of the connection.
-Typically the GUI will show the last recieved I line. The format is
-<var>I String</> As a general rule an I tag should be ommitted before a
-lengthy operation only. Things that always take a short period are not
-suited for I tags. I tags should change wnenever the methods state changes.
-Some standard forms, in order of occurance, are <var>Connecting to SITE</>,
-<var>Connecting to SITE (1.1.1.1)</>, <var>Waiting for file</>,
-<var>Authenticating</>, <var>Downloading</>, <var>Resuming (size)</>,
-<var>Computing MD5</> <var>I</> lines should never print out information that
-APT is already aware of, such as file names.
-
-<tag>R - Set final path<item>
-The R tag allows the method to tell APT that the file is present in the
-local file system. APT might copy it into a the download directory. The format
-is <var>R String</>
-
-<tag>M - MD5Sum of the file<item>
-The method is expected to compute the md5 hash on the fly as the download
-progresses. The final md5 of the file is to be output when the file is
-completed. If the md5 is not output it will not be checked! Some methods
-such as the file method will not check md5's because they are most
-commonly used on mirrors or local CD-ROM's, a paranoid option may be
-provided in future to force checking. The format is <var>M MD5-String</>
-
-<tag>L - Log output<item>
-This tag indicates a string that should be dumped to some log file. The
-string is for debugging and is not ment to be seen by the user. The format
-is <var>L String</> Log things should only be used in a completed method
-if they have special relavence to what is happening.
-</taglist>
-
-<p>
-APT monitors the progress of the transfer by watching the file size. This
-means the method must not create any temp files and must use a fairly small
-buffer. The method is also responsible for If-Modified-Since (IMS) queries
-for the object. It should check ../outputname to get the time stamp but not
-size. The size may be different because the file was uncompressed after
-it was transfed. A method must <em>never</> change the file in .., it may
-only change the output file in the current directory.
-
-<p>
-The APT 'http' program is the reference implementation of this specification,
-it implements all of the features a method is expected to do.
projects / apt.git / blobdiff