Merge remote-tracking branch 'upstream/debian/experimental' into feature/acq-trans

[apt.git] / doc / external-dependency-solver-protocol.txt

diff --git a/doc/external-dependency-solver-protocol.txt b/doc/external-dependency-solver-protocol.txt
index 7a124d8f92974127475ffb8e039a207f928a4744..14e9528c8469bf588f28cef30a9b5af3592552b3 100644 (file)
--- a/doc/external-dependency-solver-protocol.txt
+++ b/doc/external-dependency-solver-protocol.txt
@@ -1,10 +1,18 @@
-# APT External Dependency Solver Protocol (EDSP) - version 0.4
+# APT External Dependency Solver Protocol (EDSP) - version 0.5

 
 This document describes the communication protocol between APT and
 external dependency solvers. The protocol is called APT EDSP, for "APT
 External Dependency Solver Protocol".
 
 
 
 This document describes the communication protocol between APT and
 external dependency solvers. The protocol is called APT EDSP, for "APT
 External Dependency Solver Protocol".
 
 

+## Terminology
+
+In the following we use the term **architecture qualified package name**
+(or *arch-qualified package names* for short) to refer to package
+identifiers of the form "package:arch" where "package" is a package name
+and "arch" a dpkg architecture.
+
+

 ## Components
 
 - **APT**: we know this one.
 ## Components
 
 - **APT**: we know this one.


@@ -62,6 +70,7 @@ configuration documentation for more, and more up to date, information.
 - **Dir::Bin::Solvers**: absolute path of the directory where to look for
   external solvers. Defaults to `/usr/lib/apt/solvers`.
 
 - **Dir::Bin::Solvers**: absolute path of the directory where to look for
   external solvers. Defaults to `/usr/lib/apt/solvers`.
 

+

 ## Protocol
 
 When configured to use an external solver, APT will resort to it to
 ## Protocol
 
 When configured to use an external solver, APT will resort to it to


@@ -110,23 +119,31 @@ Within a dependency solving scenario, a request represents the action on
 installed packages requested by the user.
 
 A request is a single Deb 822 stanza opened by a mandatory Request field
 installed packages requested by the user.
 
 A request is a single Deb 822 stanza opened by a mandatory Request field

-and followed by a mixture of action and preference fields.
+and followed by a mixture of action, preference, and global
+configuration fields.

 
 The value of the **Request:** field is a string describing the EDSP
 protocol which will be used to communicate. At present, the string must
 
 The value of the **Request:** field is a string describing the EDSP
 protocol which will be used to communicate. At present, the string must

-be `EDSP 0.4`.
+be `EDSP 0.5`. Request fields are mainly used to identify the beginning
+of a request stanza; their actual values are otherwise not used by the
+EDSP protocol.

 
 

-a unique request identifier, such as an
-UUID. Request fields are mainly used to identify the beginning of a
-request stanza; their actual values are otherwise not used by the EDSP
-protocol.
+The following **configuration fields** are supported in request stanzas:
+
+- **Architecture:** (mandatory) The name of the *native* architecture on
+  the user machine (see also: `dpkg --print-architecture`)
+
+- **Architectures:** (optional, defaults to the native architecture) A
+  space separated list of *all* architectures known to APT (this is
+  roughly equivalent to the union of `dpkg --print-architecture` and
+  `dpkg --print-foreign-architectures`)

 
 The following **action fields** are supported in request stanzas:
 
 - **Install:** (optional, defaults to the empty string) A space
 
 The following **action fields** are supported in request stanzas:
 
 - **Install:** (optional, defaults to the empty string) A space

-  separated list of package names, with *no version attached*, to
-  install. This field denotes a list of packages that the user wants to
-  install, usually via an APT `install` request.
+  separated list of arch-qualified package names, with *no version
+  attached*, to install. This field denotes a list of packages that the
+  user wants to install, usually via an APT `install` request.

 
 - **Remove:** (optional, defaults to the empty string) Same syntax of
   Install. This field denotes a list of packages that the user wants to
 
 - **Remove:** (optional, defaults to the empty string) Same syntax of
   Install. This field denotes a list of packages that the user wants to


@@ -193,7 +210,7 @@ field. The following fields are supported in package stanzas:
 - **APT-Candidate:** (optional, defaults to `no`). Allowed values:
   `yes`, `no`. When set to `yes`, the corresponding package is the APT
   candidate for installation among all available packages with the same
 - **APT-Candidate:** (optional, defaults to `no`). Allowed values:
   `yes`, `no`. When set to `yes`, the corresponding package is the APT
   candidate for installation among all available packages with the same

-  name.
+  name and architecture.

 
 - **APT-Automatic:** (optional, defaults to `no`). Allowed values:
   `yes`, `no`. When set to `yes`, the corresponding package is marked by
 
 - **APT-Automatic:** (optional, defaults to `no`). Allowed values:
   `yes`, `no`. When set to `yes`, the corresponding package is marked by


@@ -201,6 +218,16 @@ field. The following fields are supported in package stanzas:
   should be removed by the solver only when the Autoremove action is
   requested (see Request section).
 
   should be removed by the solver only when the Autoremove action is
   requested (see Request section).
 

+- **APT-Release:** (optional) The releases the package belongs to, according to
+  APT. The format of this field is multiline with one value per line and the
+  first line (the one containing the field name) empty. Each subsequent line
+  corresponds to one of the releases the package belongs to and looks like
+  this: `o=Debian,a=unstable,n=sid,l=Debian,c=main`. That is, each release line
+  is a comma-separated list of "key=value" pairs, each of which denotes a
+  Release file entry (Origin, Label, Codename, etc.) in the format of
+  APT_PREFERENCES(5).
+
+

 ### Answer
 
 An answer from the external solver to APT is either a *solution* or an
 ### Answer
 
 An answer from the external solver to APT is either a *solution* or an


@@ -209,11 +236,11 @@ An answer from the external solver to APT is either a *solution* or an
 The following invariant on **exit codes** must hold true. When the
 external solver is *able to find a solution*, it will write the solution
 to standard output and then exit with an exit code of 0. When the
 The following invariant on **exit codes** must hold true. When the
 external solver is *able to find a solution*, it will write the solution
 to standard output and then exit with an exit code of 0. When the

-external solver is *unable to find a solution* (and s aware of that), it
-will write an error to standard output and then exit with an exit code
-of 0. An exit code other than 0 will be interpreted as a solver crash
-with no meaningful error about dependency resolution to convey to the
-user.
+external solver is *unable to find a solution* (and is aware of that),
+it will write an error to standard output and then exit with an exit
+code of 0. An exit code other than 0 will be interpreted as a solver
+crash with no meaningful error about dependency resolution to convey to
+the user.

 
 
 #### Solution
 
 
 #### Solution