Merge EDSP 0.5 w/ multi-arch support for external solvers

[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 3f2da21956d6a6c0ac9f9f42a9608891627e77a9..790f2f1ee80a511f708a86f01589f5de687a92b4 100644 (file)
--- a/doc/external-dependency-solver-protocol.txt
+++ b/doc/external-dependency-solver-protocol.txt
@@ -1,4 +1,4 @@
-# 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
@@ -110,14 +110,25 @@ 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
-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
-be `EDSP 0.4`. Request fields are mainly used to identify the beginning
+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.
 
+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
@@ -198,6 +209,15 @@ 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).
 
+- **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