Subject: [PATCH] Document smart http

From: Nguyễn Thái Ngọc Duy <[email-masked]>
Date: Tue, 20 Aug 2013 12:08:08 +0700

This may provide some clues for those who want to modify smart http
code as smart http is pretty much undocumented. Smart http "document"
so far is a few commit messages and the source code.

Signed-off-by: Nguyễn Thái Ngọc Duy <[email-masked]>
---
 Documentation/git-fetch-pack.txt          | 11 +++--
 Documentation/git-receive-pack.txt        | 12 +++++-
 Documentation/git-send-pack.txt           |  9 +++-
 Documentation/git-upload-pack.txt         |  9 +++-
 Documentation/technical/pack-protocol.txt | 69 +++++++++++++++++++++++++++++++
 5 files changed, 103 insertions(+), 7 deletions(-)

diff --git a/Documentation/git-fetch-pack.txt b/Documentation/git-fetch-pack.txt
index 1e71754..85a9437 100644
--- a/Documentation/git-fetch-pack.txt
+++ b/Documentation/git-fetch-pack.txt
@@ -9,10 +9,7 @@ git-fetch-pack - Receive missing objects from another repository
 SYNOPSIS
 --------
 [verse]
-'git fetch-pack' [--all] [--quiet|-q] [--keep|-k] [--thin] [--include-tag]
-	[--upload-pack=<git-upload-pack>]
-	[--depth=<n>] [--no-progress]
-	[-v] [<host>:]<directory> [<refs>...]
+'git fetch-pack' [options] [<host>:]<directory> [<refs>...]
 
 DESCRIPTION
 -----------
@@ -90,6 +87,12 @@ be in a separate packet, and the list must end with a flush packet.
 --no-progress::
 	Do not show the progress.
 
+--stateless-rpc::
+	Smart HTTP mode.
+
+--lock-pack::
+	Issue "lock" command to the remote helper via stdout.
+
 -v::
 	Run verbosely.
 
diff --git a/Documentation/git-receive-pack.txt b/Documentation/git-receive-pack.txt
index b1f7dc6..0b2029c 100644
--- a/Documentation/git-receive-pack.txt
+++ b/Documentation/git-receive-pack.txt
@@ -9,7 +9,7 @@ git-receive-pack - Receive what is pushed into the repository
 SYNOPSIS
 --------
 [verse]
-'git-receive-pack' <directory>
+'git-receive-pack' [options] <directory>
 
 DESCRIPTION
 -----------
@@ -35,6 +35,16 @@ are not fast-forwards.
 
 OPTIONS
 -------
+--stateless-rpc::
+	Smart HTTP mode.
+
+--advertise-refs::
+	Only the initial ref advertisement is output then exits
+	immediately.
+
+--quiet::
+	Make unpack-objects at the receive-pack end quiet.
+
 <directory>::
 	The repository to sync into.
 
diff --git a/Documentation/git-send-pack.txt b/Documentation/git-send-pack.txt
index dc3a568..6cee3d4 100644
--- a/Documentation/git-send-pack.txt
+++ b/Documentation/git-send-pack.txt
@@ -9,7 +9,7 @@ git-send-pack - Push objects over Git protocol to another repository
 SYNOPSIS
 --------
 [verse]
-'git send-pack' [--all] [--dry-run] [--force] [--receive-pack=<git-receive-pack>] [--verbose] [--thin] [<host>:]<directory> [<ref>...]
+'git send-pack' [options] [<host>:]<directory> [<ref>...]
 
 DESCRIPTION
 -----------
@@ -52,6 +52,13 @@ OPTIONS
 	Send a "thin" pack, which records objects in deltified form based
 	on objects not included in the pack to reduce network traffic.
 
+--stateless-rpc::
+	Smart HTTP mode.
+
+--helper-status:
+	Issue status commands (e.g. "ok" or "error") to the remote
+	helper via stdout.
+
 <host>::
 	A remote host to house the repository.  When this
 	part is specified, 'git-receive-pack' is invoked via
diff --git a/Documentation/git-upload-pack.txt b/Documentation/git-upload-pack.txt
index 0abc806..ce9a455 100644
--- a/Documentation/git-upload-pack.txt
+++ b/Documentation/git-upload-pack.txt
@@ -9,7 +9,7 @@ git-upload-pack - Send objects packed back to git-fetch-pack
 SYNOPSIS
 --------
 [verse]
-'git-upload-pack' [--strict] [--timeout=<n>] <directory>
+'git-upload-pack' [options] <directory>
 
 DESCRIPTION
 -----------
@@ -31,6 +31,13 @@ OPTIONS
 --timeout=<n>::
 	Interrupt transfer after <n> seconds of inactivity.
 
+--stateless-rpc::
+	Smart HTTP mode.
+
+--advertise-refs::
+	Only the initial ref advertisement is output then exits
+	immediately.
+
 <directory>::
 	The repository to sync from.
 
diff --git a/Documentation/technical/pack-protocol.txt b/Documentation/technical/pack-protocol.txt
index b898e97..7590394 100644
--- a/Documentation/technical/pack-protocol.txt
+++ b/Documentation/technical/pack-protocol.txt
@@ -546,3 +546,72 @@ An example client/server communication might look like this:
    S: 0018ok refs/heads/debug\n
    S: 002ang refs/heads/master non-fast-forward\n
 ----
+
+Smart HTTP Transport
+--------------------
+
+Smart HTTP protocol is basically "git protocol on top of http". The
+base protocol is modified slightly to fit HTTP processing model: no
+bidirectional full-duplex connections, the program may read the
+request, write a response and must exit. Any negotiation is broken
+down into many separate GET or POST requests. The server is
+stateless. The client must send enough information so that the server
+can recreate the previous state.
+
+Reference Discovery
+-------------------
+
+The server end always sends the list of references in both push and
+fetch cases. This ref list is retrieved by the client's sending HTTP
+GET request to a smart http url ending with
+"/info/refs?service=<service>" where <service> could be either
+git-upload-pack or git-receive-pack for fetching or pushing
+respectively. The output is in pkt-line format.
+
+----
+  advertised-refs  =  service
+		      flush-pkt
+		      (no-refs / list-of-refs)
+		      flush-pkt
+
+  service          =  PKT-LINE("# service=" service-name)
+  service-name     =  ("git-upload-pack" / "git-receive-pack")
+
+  no-refs          =  PKT-LINE(zero-id SP "capabilities^{}"
+		      NUL capability-list LF)
+
+  list-of-refs     =  first-ref *other-ref
+  first-ref        =  PKT-LINE(obj-id SP refname
+		      NUL capability-list LF)
+
+  other-ref        =  PKT-LINE(other-tip / other-peeled)
+  other-tip        =  obj-id SP refname LF
+  other-peeled     =  obj-id SP refname "^{}" LF
+
+  capability-list  =  capability *(SP capability)
+  capability       =  1*(LC_ALPHA / DIGIT / "-" / "_")
+  LC_ALPHA         =  %x61-7A
+----
+
+Packfile Negotiation
+--------------------
+
+For fetching, packet negotiation is via a series of HTTP POST requests
+to an url ending with "/git-upload-pack" with the content in pkt-line
+format. git-upload-pack's response consists of a "service" line like
+in Reference Discovery followed by normal git-upload-pack packet
+lines. Capability multi_ack_detailed is required by Smart HTTP.
+
+Common objects that are discovered are appended onto the request as
+have lines and are sent again on the next request. This allows the
+remote side to reinitialize its in-memory list of common objects
+during the next request and the remote does not need to maintain the
+negotiation state.
+
+Reference Update Request
+------------------------
+
+For pushing, a HTTP POST request is sent to an url ending with
+"/git-receive-pack" with the content in pkt-line format.
+git-receive-pack's response consists of a "service" line like in
+Reference Discovery followed by normal git-receive-pack packet lines.
-- 
1.8.2.82.gc24b958