DE.SETF.AMQP: a Common Lisp client library for AMQP

de.setf.amqp implements a native Common Lisp client library for the 'Advanced Message Queuing Protocol' (AMQP). The implementation comprises wire-level codecs, implementations for the standard protocol objects and methods, a functional interface for message-, stream- and object-based i/o, and a device-level simple-stream implementation.

The library targets the revisions of the published AMQP protocol as of versions 0.8, 0.9, and 0.10. This means that it should work with respective RabbitMQ, OpenAMQ, and Qpid implementations. The implementation architecture should also accommodate a control structure appropriate for the prospective 1.0 version - as least as described in preliminary drafts. For each version, a distinct package comprises the object and method definitions for protocol entities and codecs as generated from the respective specification documents.[1] Each collection is a complete projection, which means there is some amount of duplication. The names - classes, operators, fields, packages and directories all follow more-or-less the naming conventions of the xml protocol documents[2]:

AMQP-1-1-0-8-0	version 0.8	[amqp0-8.xml, amqp0-8.pdf (2006-06)]
AMQP-1-1-0-9-0	version 0.9	[amqp0-9.xml, amqp0-9.pdf (2006-12)]
AMQP-1-1-0-9-1	version 0.9r1	[amqp0-9-1.xml, amqp0-9-1.pdf (2008-11-24)]
AMQP-1-1-0-10-0	version 0.10	[amqp.0-10.xml, amqp.0-10.pdf (2008-02-20)]

In order to modify the translation and/or generate new codecs consult the :de.setf.amqp.tools module.

All protocol versions are expressed through a common interface[3] which is specialized for the common abstract classes. The initial connection phase determines the correct concrete connection implementation to be used to communicate with the broker. Given which the other concrete object and method classes are elected from the same package. One determines the version to be supported directly by loading the respective version's .asd file, which makes its connection class available for negotiation.

Status

This is intended as the base for a distributed semantic store. What one has here is a reasonably complete engineering prototype. It consumes phenomenal amounts of memory and runs astonishingly slowly: 5 - 10 milliseconds and 1 to 10 thousand bytes per round trip. A request entails ten levels of generic function dispatch, half of which require keyword processing. A response call stack is about as deep, but with somewhat less keyword processing. As almost everything between the interface commands and the frame buffers is generated code, once it is clear which aspects should remain available for specialization and/or optional arguments, the protocol call stack would benefit from recasting uninteresting elements as ordinary functions of fixed arguments - depending on implementation type, by a factor of ten to sixty.

It would also be nice to generate a table similar to RabbitMQ's to record protocol conformance and compatibility with brokers. Eventually. The present tests are limited to

• codec unit tests which validate the respective version's codecs for default argument values.
• in-memory loop-back tests, used to ensure (for a recent version) that a round-trip does not cons
• simple data exchanges with a broker.

An Example

The library has been built and probed in the following combinations

AMQP broker lisp implementation	RabbittMQ	QPID
MCL	MCL-5.2, RabbitMQ 1.7.1, AMQP-0.8r0	MCL-5.2, QPID-0.5, AMQP-0.9r1
CCL		CCL-1.4, QPID-0.5, AMQP-0.9r1
SBCL		SBCL-1.0.35, QPID-0.5, AMQP-0.9r1

For example,

$ sbcl
This is SBCL 1.0.35, an implementation of ANSI Common Lisp.
More information about SBCL is available at <http://www.sbcl.org/>.

* (in-package :amqp.i)

#<PACKAGE "DE.SETF.AMQP.IMPLEMENTATION">
* (defparameter *c* (make-instance 'amqp:connection :uri "amqp://guest:guest@localhost/"))

*C*
* (defparameter *ch1* (amqp:channel *c* :uri (uri "amqp:///")))

*CH1*
* (defparameter *ch1.basic* (amqp:basic *ch1*))

*CH1.BASIC*
* (defparameter *ch1.ex* (amqp:exchange *ch1*  :exchange "ex" :type "direct"))

*CH1.EX*
* (defparameter *ch1.q*  (amqp:queue *ch1* :queue "q1"))

*CH1.Q*
* (amqp:request-declare *ch1.q*)

#<AMQP-1-1-0-9-1:QUEUE {11D7A0F1}>
* (amqp:request-bind *ch1.q* :exchange *ch1.ex* :queue *ch1.q* :routing-key "/")

#<AMQP-1-1-0-9-1:QUEUE {11D7A0F1}>
* (defparameter *ch2* (amqp:channel *c* :uri (uri "amqp:///")))

*CH2* 
* (defparameter *ch2.basic* (amqp:basic *ch2*))

*CH2.BASIC*
* (defparameter *ch2.q*  (amqp:queue *ch2* :queue "q1"))

*CH2.Q*
* (amqp:request-declare *ch2.q*)

#<AMQP-1-1-0-9-1:QUEUE {11DA6891}>
* (list
    (amqp:request-publish *ch1.basic* :exchange *ch1.ex*
                          :body (format nil "this is ~a" (gensym "test #"))
                          :routing-key "/")
    (amqp:request-get *ch2.basic* :queue *ch2.q*))

("this is test #1282" "this is test #1624")
* (amqp:request-get *ch2.basic* :queue *ch2.q*)

"this is test #1820"
* (amqp:request-get *ch2.basic* :queue *ch2.q*)

"this is test #1998"
* (amqp:request-get *ch2.basic* :queue *ch2.q*)

"this is test #2011"
* (amqp:request-get *ch2.basic* :queue *ch2.q*)

"this is test #2014"
* (amqp:request-get *ch2.basic* :queue *ch2.q*)

"this is test #2022"
* (amqp:request-get *ch2.basic* :queue *ch2.q*)

"this is test #2028"
* (amqp:request-get *ch2.basic* :queue *ch2.q*)

"this is test #2179"
* (amqp:request-get *ch2.basic* :queue *ch2.q*)

"this is test #1282"
* (amqp:request-get *ch2.basic* :queue *ch2.q*)

NIL
* 

Which, as an aside, illustrates that brokered messages persist between connections until they have been consumed. Of which a default QPID broker with no persistence support was observed to cache only about 500k bytes (ca. 25,000 messages of 20 bytes each).

An introduction to the API is taking shape. In the meantime, there is a package index, there are a few examples for the library proper and for the RabbitMQ library emulation.

common-lisp.net hosts a mailing list and a trac instance for discussions and/or reports.

Changes

• 2010-06-10 : corrected and completed float codecs
• 2011-11-20 : added user-id default for publish to cooperate with rabbitmq @2.6

Downloading

A .dmg is available for MCL-5.2. Saved images are available for ccl and sbcl.

Building

In principle, de.setf.amqp is built with asdf. Once one has the sources and the asdf configuration in place, evaluate

(asdf:operate 'asdf:load-op :de.setf.amqp.amqp-1-1-0-8-0)
(asdf:operate 'asdf:load-op :de.setf.amqp.amqp-1-1-0-9-0)
(asdf:operate 'asdf:load-op :de.setf.amqp.amqp-1-1-0-9-1)

to load the respective version. The versions intend to be compatible and connections should negotiate automatically to use the correct implementation. Please consult the detailed instructions for the respective runtime for more information.

Licensing

This version is released under version 3 of the GNU Affero license (GAL).[5] The required components are included as per the respective licenses and covered, in this combined form, under the GAL as well

• alexandria : Public Domain
• usocket : MIT, through 2007. later work unspecified
  • 2003 Erik Enge
  • 2006-2007 Erik Huelsmann
• closer-mop : MIT-style
  • 2005 - 2010 Pascal Costanza
• bordeaux-threads : MIT-style, with additional attributions undated.[6]
  • -2006 Greg Pfeil
• cl-ppcre : equivalent to MIT
  • 2002-2008, Dr. Edmund Weitz
• com.b9.puri : LLGPL, by which com.b9.puri.ppcre is also covered by the LLGPL
  • 1999-2001 Franz, Inc.
  • 2003 Kevin Rosenberg

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