package amqp-client
Install
Dune Dependency
Authors
Maintainers
Sources
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README.md.html
OCaml client library for AMQP
Amqp-client is a AMQP client library written in pure OCaml. The library implements AMQP protocol version 0.9.1 as well as RabbitMQ-specific extensions. It supports both Core Async and Lwt threading models.
Amqp-client is tested extensively against RabbitMQ, but should work with any AMQP server.
The library exposes low level protocol handling through Amqp_spec
and Amqp_framing
modules as well as a high level interface though module Amqp
.
The high level interface exposes usage patterns such as
create queue
consume from a queue
post message to a queue
create exchange
bind a queue to an exchange
post message to an exchange
RPC client / server
The library requires all resources to be explicitly allocated to avoid crashes because a service is relying on other services to allocate AMQP resources (exchanges, queues etc.).
Channels and consumers are tagged with an id, host name, pid etc. to ease tracing on AMQP level.
The design philiosiphy of the library is fail fast, meaning that if any external state changes (e.g. connection closes unexpectibly, queu consumption is cancelled) an exception is raised, and It is adviced to let the process crash and restart initialization rather than going through the complex task of reparing the state.
Build infrastructure
The system is not functorized over an abstraction to the threading model. Instead the build system chooses which threading model abstraction to be used and stacially compiles it in. This has the advantage that files do not need to carry functor boilerplate
The disadvantage is that it does not allow users to supply their own threading model implementation.
Opam
It is recommended to install the package though opam. You should choose the package matching the concurrency library that your application will use
For Janestreet async: opam install amqp-client-async
For Ocsigen Lwt: opam install amqp-client-lwt
Manual build
To build the library
make build
make install
will install both Lwt and Async versions.
Using the library
To compile using Async do:
ocamlfind ocamlopt -thread -package amqp-client-async myprog.ml
To compile using the Lwt version of the library do:
ocamlfind ocamlopt -thread -package amqp-client-lwt myprog.ml
Examples
Async
Install the async version of the library: opam install amqp-client-async
open Async
open Amqp_client_async
let host = "localhost"
let run () =
Amqp.Connection.connect ~id:"MyConnection" host >>= fun connection ->
Amqp.Connection.open_channel ~id:"MyChannel" Amqp.Channel.no_confirm connection >>= fun channel ->
Amqp.Queue.declare channel "MyQueue" >>= fun queue ->
Amqp.Queue.publish channel queue (Amqp.Message.make "My Message Payload") >>= function `Ok ->
Amqp.Channel.close channel >>= fun () ->
Amqp.Connection.close connection >>= fun () ->
Shutdown.shutdown 0; return ()
let _ =
Thread_safe.block_on_async_exn run
Compile with:
$ ocamlfind ocamlopt -thread -package amqp-client-async amqp_example.ml -linkpkg -o amqp_example
Lwt
Install the lwt version of the library: opam install amqp-client-lwt
open Lwt.Infix
open Amqp_client_lwt
let host = "localhost"
let run () =
Amqp.Connection.connect ~id:"MyConnection" host >>= fun connection ->
Amqp.Connection.open_channel ~id:"MyChannel" Amqp.Channel.no_confirm connection >>= fun channel ->
Amqp.Queue.declare channel "MyQueue" >>= fun queue ->
Amqp.Queue.publish channel queue (Amqp.Message.make "My Message Payload") >>= function `Ok ->
Amqp.Channel.close channel >>= fun () ->
Amqp.Connection.close connection >>= fun () ->
Lwt.return ()
let _ =
Lwt_main.run (run ())
Compile with:
$ ocamlfind ocamlopt -thread -package amqp-client-lwt amqp_example.ml -linkpkg -o amqp_example
More examples are available here: https://github.com/andersfugmann/amqp-client/tree/master/examples
To compile the examples do: make examples
, which will place the binaries under _build/default/examples/
.
It is recommended to use dune for building projects and not invoke ocaml/ocamlfind from the command line explicitly.
A simple dune file for a project with one file called: example.ml
looks like this:
(executable
(name example)
(libraies amqp-client-async)
)
To build do dune build example.exe
. For more information on dune, see https://dune.readthedocs.io/en/latest/