Ubuntu14.04+RabbitMQ3.6.3+Golang的最佳实践
目录
目录
1、RabbitMQ介绍
1.1、什么是RabbitMQ？
RabbitMQ 是由 LShift 提供的一个 Advanced Message Queuing Protocol (AMQP) 的开源实现，由以高性能、健壮以及可伸缩性出名的 Erlang 写成，因此也是继承了这些优点。
1.2、什么是AMQP?
AMQP，即Advanced Message Queuing Protocol，高级消息队列协议，是应用层协议的一个开放标准，为面向消息的中间件设计。它从生产者接收消息并递送给消费者，在这个过程中，根据规则进行路由，缓存与持久化。
AMQP的主要特征是面向消息、队列、路由（包括点对点和发布/订阅）、可靠性、安全。
RabbitMQ是一个开源的AMQP实现，服务器端用Erlang语言编写，支持多种客户端，如：Python、Ruby、.NET、Java、JMS、C、PHP、ActionScript、XMPP、STOMP等，支持AJAX。用于在分布式系统中存储转发消息，在易用性、扩展性、高可用性等方面表现不俗。
而在AMQP中主要有两个组件：Exchange 和 Queue （在 AMQP 1.0 里还会有变动），如下图所示，绿色的 X 就是 Exchange ，红色的是 Queue ，这两者都在 Server 端，又称作 Broker ，这部分是 RabbitMQ 实现的，而蓝色的则是客户端，通常有 Producer 和 Consumer 两种类型：
1.3、RabbitMQ的基础概念
- Broker：简单来说就是消息队列服务器实体
- Exchange：消息交换机，它指定消息按什么规则，路由到哪个队列
- Queue：消息队列载体，每个消息都会被投入到一个或多个队列
- Binding：绑定，它的作用就是把exchange和queue按照路由规则绑定起来
- Routing Key：路由关键字，exchange根据这个关键字进行消息投递
- vhost：虚拟主机，一个broker里可以开设多个vhost，用作不同用户的权限分离
- producer：消息生产者，就是投递消息的程序
- consumer：消息消费者，就是接受消息的程序
- channel：消息通道，在客户端的每个连接里，可建立多个channel，每个channel代表一个会话任务
1.4、RabbitMQ的特性
- 可靠性：包括消息持久化，消费者和生产者的消息确认
- 灵活路由：遵循AMQP协议，支持多种Exchange类型实现不同路由策略
- 分布式：集群的支持，包括本地网络与远程网络
- 高可用性：支持主从备份与镜像队列
- 多语言支持：支持多语言的客户端
- WEB界面管理：可以管理用户权限，exhange，queue，binding，与实时监控
- 访问控制：基于vhosts实现访问控制
- 调试追踪：支持tracing，方便调试
2、RabbitMQ的官网在哪里？
3、RabbitMQ在哪里下载?
http://www.rabbitmq.com/download.html
4、如何安装RabbitMQ
4.1、通过安装RabbitMQ的源来安装
在Ubuntu上安装RabbitMQ非常简单
lion@ubuntu1404:~$ sudo echo 'deb http://www.rabbitmq.com/debian/ testing main' | sudo tee /etc/apt/sources.list.d/rabbitmq.list
lion@ubuntu1404:~$ wget -O- https://www.rabbitmq.com/rabbitmq-release-signing-key.asc | sudo apt-key add -
lion@ubuntu1404:~$ sudo apt-get update
lion@ubuntu1404:~$ sudo apt-get install rabbitmq-server
其他系统安装方法:http://www.rabbitmq.com/download.html
4.2、通过源码安装
本文中的实例，主要通过源码安装来演示。
4.2.1、安装Erlang
相关安装文档：http://erlang.org/erldoc
lion@node1:~$ sudo apt-get install -y erlang-nox erlang-dev erlang-src
4.2.2、Rabbitmq 3.6.3安装
相关安装文档：http://www.rabbitmq.com/install-generic-unix.html。
我们先下载源码并解压
lion@node1:~$ mkdir -p _app
lion@node1:~/_app$ wget http://www.rabbitmq.com/releases/rabbitmq-server/v3.6.3/rabbitmq-server-generic-unix-3.6.3.tar.xz
lion@node1:~/_app$ xz -d rabbitmq-server-generic-unix-3.6.3.tar.xz
lion@node1:~/_app$ tar -xvf rabbitmq-server-generic-unix-3.6.3.tar
lion@node1:~/_app$ cd rabbitmq_server-3.6.3
设置环境变量$RABBITMQ_HOME
lion@node1:~$ vi .bashrc
在.bashrc中添加以下内容
export RABBITMQ_HOME="/home/lion/_app/rabbitmq_server-3.6.3"
export PATH="$RABBITMQ_HOME/sbin:$PATH"
让环境变量生效
lion@node1:~$ source .bashrc
启动Rabbitmq
lion@node1:~$ rabbitmq-server
安装以后可以通过下面的命令，停止、启动：
lion@node1:~$ rabbitmqctl stop
lion@node1:~$ rabbitmqctl start
4.3、开启web管理插件
创建一个用户lion，并设置密码123456：
lion@node1:~$ rabbitmqctl add_user lion 123456
可以通过下面的命令，查看现有的用户更表
lion@node1:~$ rabbitmqctl list_users
Listing users ...
guest [administrator]
lion []
这个时候lion用户是不能访问web管理插件的，需要配置用户角色，用户角色可分为五类，超级管理员, 监控者, 策略制定者, 普通管理者以及其他。
- 超级管理员(administrator)
可登陆管理控制台(启用management plugin的情况下)，可查看所有的信息，并且可以对用户，策略(policy)进行操作。
- 监控者(monitoring)
可登陆管理控制台(启用management plugin的情况下)，同时可以查看rabbitmq节点的相关信息(进程数，内存使用情况，磁盘使用情况等)
- 策略制定者(policymaker)
可登陆管理控制台(启用management plugin的情况下), 同时可以对policy进行管理。但无法查看节点的相关信息。
- 普通管理者(management)
仅可登陆管理控制台(启用management plugin的情况下)，无法看到节点信息，也无法对策略进行管理。
- 其他
无法登陆管理控制台，通常就是普通的生产者和消费者。
通过下面的命令，可以将lion添加到administrator用户组：
lion@node1:~$ rabbitmqctl set_user_tags lion administrator
然后可以用下面的命令来启用/信上管理插件：
lion@node1:~$ rabbitmq-plugins enable rabbitmq_management (启用插件)
lion@node1:~$ rabbitmq-plugins disable rabbitmq_management (禁用插件)
通过浏览访问 http://127.0.0.1:15672/
输入用户名lion,密码123456就可以看到后台了。
rabbitmqctl的更多命令参考：http://www.rabbitmq.com/man/rabbitmqctl.1.man.html
4.4、RabbitMQ 的配置文件介绍
RabbitMQ的配置文件目录默认是$RABBITMQ_HOME/etc/rabbitmq/rabbitmq-env.conf，如果文件不存在，可以自己创建。
配置文件全部说明地址：http://www.rabbitmq.com/configure.html#configuration-file
%% -*- mode: erlang -*-
%% ----------------------------------------------------------------------------
%% RabbitMQ Sample Configuration File.
%%
%% See http://www.rabbitmq.com/configure.html for details.
%% ----------------------------------------------------------------------------
[
{rabbit,
[%%
%% Network Connectivity
%% ====================
%%
%% By default, RabbitMQ will listen on all interfaces, using
%% the standard (reserved) AMQP port.
%% 默认的监听端口
%% {tcp_listeners, [5672]},
%% To listen on a specific interface, provide a tuple of {IpAddress, Port}.
%% For example, to listen only on localhost for both IPv4 and IPv6:
%% 也可以使用下面的格式进行指定IP和端口的监听
%% {tcp_listeners, [{"127.0.0.1", 5672},
%% {"::1", 5672}]},
%% SSL listeners are configured in the same fashion as TCP listeners,
%% including the option to control the choice of interface.
%% SSL连接端口配置
%% {ssl_listeners, [5671]},
%% Number of Erlang processes that will accept connections for the TCP
%% and SSL listeners.
%% TCP连接的进程数
%% {num_tcp_acceptors, 10},
%% {num_ssl_acceptors, 1},
%% Maximum time for AMQP 0-8/0-9/0-9-1 handshake (after socket connection
%% and SSL handshake), in milliseconds.
%% 超时时间，单位毫秒
%% {handshake_timeout, 10000},
%% Log levels (currently just used for connection logging).
%% One of 'debug', 'info', 'warning', 'error' or 'none', in decreasing
%% order of verbosity. Defaults to 'info'.
%% 日志的级别，默认是info
%% {log_levels, [{connection, info}, {channel, info}]},
%% Set to 'true' to perform reverse DNS lookups when accepting a
%% connection. Hostnames will then be shown instead of IP addresses
%% in rabbitmqctl and the management plugin.
%%
%% {reverse_dns_lookups, true},
%%
%% Security / AAA
%% ==============
%% 安全配置
%% The default "guest" user is only permitted to access the server
%% via a loopback interface (e.g. localhost).
%% {loopback_users, [<<"guest">>]},
%%
%% Uncomment the following line if you want to allow access to the
%% guest user from anywhere on the network.
%% {loopback_users, []},
%% Configuring SSL.
%% See http://www.rabbitmq.com/ssl.html for full documentation.
%%
%% {ssl_options, [{cacertfile, "/path/to/testca/cacert.pem"},
%% {certfile, "/path/to/server/cert.pem"},
%% {keyfile, "/path/to/server/key.pem"},
%% {verify, verify_peer},
%% {fail_if_no_peer_cert, false}]},
%% Choose the available SASL mechanism(s) to expose.
%% The two default (built in) mechanisms are 'PLAIN' and
%% 'AMQPLAIN'. Additional mechanisms can be added via
%% plugins.
%%
%% See http://www.rabbitmq.com/authentication.html for more details.
%%
%% {auth_mechanisms, ['PLAIN', 'AMQPLAIN']},
%% Select an authentication database to use. RabbitMQ comes bundled
%% with a built-in auth-database, based on mnesia.
%%
%% {auth_backends, [rabbit_auth_backend_internal]},
%% Configurations supporting the rabbitmq_auth_mechanism_ssl and
%% rabbitmq_auth_backend_ldap plugins.
%%
%% NB: These options require that the relevant plugin is enabled.
%% See http://www.rabbitmq.com/plugins.html for further details.
%% The RabbitMQ-auth-mechanism-ssl plugin makes it possible to
%% authenticate a user based on the client's SSL certificate.
%%
%% To use auth-mechanism-ssl, add to or replace the auth_mechanisms
%% list with the entry 'EXTERNAL'.
%%
%% {auth_mechanisms, ['EXTERNAL']},
%% The rabbitmq_auth_backend_ldap plugin allows the broker to
%% perform authentication and authorisation by deferring to an
%% external LDAP server.
%%
%% For more information about configuring the LDAP backend, see
%% http://www.rabbitmq.com/ldap.html.
%%
%% Enable the LDAP auth backend by adding to or replacing the
%% auth_backends entry:
%%
%% {auth_backends, [rabbit_auth_backend_ldap]},
%% This pertains to both the rabbitmq_auth_mechanism_ssl plugin and
%% STOMP ssl_cert_login configurations. See the rabbitmq_stomp
%% configuration section later in this file and the README in
%% https://github.com/rabbitmq/rabbitmq-auth-mechanism-ssl for further
%% details.
%%
%% To use the SSL cert's CN instead of its DN as the username
%%
%% {ssl_cert_login_from, common_name},
%% SSL handshake timeout, in milliseconds.
%%
%% {ssl_handshake_timeout, 5000},
%% Password hashing implementation. Will only affect newly
%% created users. To recalculate hash for an existing user
%% it's necessary to update her password.
%%
%% {password_hashing_module, rabbit_password_hashing_sha256},
%%
%% Default User / VHost
%% ====================
%% 用户访问设置
%% On first start RabbitMQ will create a vhost and a user. These
%% config items control what gets created. See
%% http://www.rabbitmq.com/access-control.html for further
%% information about vhosts and access control.
%%
%% {default_vhost, <<"/">>},
%% {default_user, <<"guest">>},
%% {default_pass, <<"guest">>},
%% {default_permissions, [<<".*">>, <<".*">>, <<".*">>]},
%% Tags for default user
%%
%% For more details about tags, see the documentation for the
%% Management Plugin at http://www.rabbitmq.com/management.html.
%%
%% {default_user_tags, [administrator]},
%%
%% Additional network and protocol related configuration
%% =====================================================
%%
%% Set the default AMQP heartbeat delay (in seconds).
%% 设置默认AMQP心跳延迟（秒）
%% {heartbeat, 600},
%% Set the max permissible size of an AMQP frame (in bytes).
%%
%% {frame_max, 131072},
%% Set the max frame size the server will accept before connection
%% tuning occurs
%%
%% {initial_frame_max, 4096},
%% Set the max permissible number of channels per connection.
%% 0 means "no limit".
%%
%% {channel_max, 128},
%% Customising Socket Options.
%%
%% See (http://www.erlang.org/doc/man/inet.html#setopts-2) for
%% further documentation.
%%
%% {tcp_listen_options, [{backlog, 128},
%% {nodelay, true},
%% {exit_on_close, false}]},
%%
%% Resource Limits & Flow Control
%% ==============================
%%
%% See http://www.rabbitmq.com/memory.html for full details.
%% Memory-based Flow Control threshold.
%%
%% {vm_memory_high_watermark, 0.4},
%% Alternatively, we can set a limit (in bytes) of RAM used by the node.
%%
%% {vm_memory_high_watermark, {absolute, 1073741824}},
%%
%% Or you can set absolute value using memory units.
%%
%% {vm_memory_high_watermark, {absolute, "1024M"}},
%%
%% Supported units suffixes:
%%
%% k, kiB: kibibytes (2^10 bytes)
%% M, MiB: mebibytes (2^20)
%% G, GiB: gibibytes (2^30)
%% kB: kilobytes (10^3)
%% MB: megabytes (10^6)
%% GB: gigabytes (10^9)
%% Fraction of the high watermark limit at which queues start to
%% page message out to disc in order to free up memory.
%%
%% Values greater than 0.9 can be dangerous and should be used carefully.
%% 内存最大使用比例
%% {vm_memory_high_watermark_paging_ratio, 0.5},
%% Interval (in milliseconds) at which we perform the check of the memory
%% levels against the watermarks.
%% 检查内存的间隔(毫秒)
%% {memory_monitor_interval, 2500},
%% Set disk free limit (in bytes). Once free disk space reaches this
%% lower bound, a disk alarm will be set - see the documentation
%% listed above for more details.
%%
%% {disk_free_limit, 50000000},
%%
%% Or you can set it using memory units (same as in vm_memory_high_watermark)
%% {disk_free_limit, "50MB"},
%% {disk_free_limit, "50000kB"},
%% {disk_free_limit, "2GB"},
%% Alternatively, we can set a limit relative to total available RAM.
%%
%% Values lower than 1.0 can be dangerous and should be used carefully.
%% {disk_free_limit, {mem_relative, 2.0}},
%%
%% Misc/Advanced Options
%% =====================
%%
%% NB: Change these only if you understand what you are doing!
%%
%% To announce custom properties to clients on connection:
%%
%% {server_properties, []},
%% How to respond to cluster partitions.
%% See http://www.rabbitmq.com/partitions.html for further details.
%%
%% {cluster_partition_handling, ignore},
%% Make clustering happen *automatically* at startup - only applied
%% to nodes that have just been reset or started for the first time.
%% See http://www.rabbitmq.com/clustering.html#auto-config for
%% further details.
%% 设置集群启动的节点
%% {cluster_nodes, {['rabbit@my.host.com'], disc}},
%% Interval (in milliseconds) at which we send keepalive messages
%% to other cluster members. Note that this is not the same thing
%% as net_ticktime; missed keepalive messages will not cause nodes
%% to be considered down.
%% 集群消息同步的时间(毫秒)
%% {cluster_keepalive_interval, 10000},
%% Set (internal) statistics collection granularity.
%%
%% {collect_statistics, none},
%% Statistics collection interval (in milliseconds).
%%
%% {collect_statistics_interval, 5000},
%% Explicitly enable/disable hipe compilation.
%%
%% {hipe_compile, true},
%% Timeout used when waiting for Mnesia tables in a cluster to
%% become available.
%%
%% {mnesia_table_loading_timeout, 30000},
%% Size in bytes below which to embed messages in the queue index. See
%% http://www.rabbitmq.com/persistence-conf.html
%%
%% {queue_index_embed_msgs_below, 4096}
]},
%% ----------------------------------------------------------------------------
%% Advanced Erlang Networking/Clustering Options.
%%
%% See http://www.rabbitmq.com/clustering.html for details
%% ----------------------------------------------------------------------------
{kernel,
[%% Sets the net_kernel tick time.
%% Please see http://erlang.org/doc/man/kernel_app.html and
%% http://www.rabbitmq.com/nettick.html for further details.
%%
%% {net_ticktime, 60}
]},
%% ----------------------------------------------------------------------------
%% RabbitMQ Management Plugin
%%
%% See http://www.rabbitmq.com/management.html for details
%% ----------------------------------------------------------------------------
{rabbitmq_management,
[%% Pre-Load schema definitions from the following JSON file. See
%% http://www.rabbitmq.com/management.html#load-definitions
%%
%% {load_definitions, "/path/to/schema.json"},
%% Log all requests to the management HTTP API to a file.
%% 所有请求的HTTP API文件日志的路径。
%% {http_log_dir, "/path/to/access.log"},
%% Change the port on which the HTTP listener listens,
%% specifying an interface for the web server to bind to.
%% Also set the listener to use SSL and provide SSL options.
%% Web管理的地址和端口
%% {listener, [{port, 12345},
%% {ip, "127.0.0.1"},
%% {ssl, true},
%% {ssl_opts, [{cacertfile, "/path/to/cacert.pem"},
%% {certfile, "/path/to/cert.pem"},
%% {keyfile, "/path/to/key.pem"}]}]},
%% One of 'basic', 'detailed' or 'none'. See
%% http://www.rabbitmq.com/management.html#fine-stats for more details.
%% {rates_mode, basic},
%% Configure how long aggregated data (such as message rates and queue
%% lengths) is retained. Please read the plugin's documentation in
%% http://www.rabbitmq.com/management.html#configuration for more
%% details.
%%
%% {sample_retention_policies,
%% [{global, [{60, 5}, {3600, 60}, {86400, 1200}]},
%% {basic, [{60, 5}, {3600, 60}]},
%% {detailed, [{10, 5}]}]}
]},
%% ----------------------------------------------------------------------------
%% RabbitMQ Shovel Plugin
%%
%% See http://www.rabbitmq.com/shovel.html for details
%% ----------------------------------------------------------------------------
{rabbitmq_shovel,
[{shovels,
[%% A named shovel worker.
%% {my_first_shovel,
%% [
%% List the source broker(s) from which to consume.
%%
%% {sources,
%% [%% URI(s) and pre-declarations for all source broker(s).
%% {brokers, ["amqp://user:password@host.domain/my_vhost"]},
%% {declarations, []}
%% ]},
%% List the destination broker(s) to publish to.
%% {destinations,
%% [%% A singular version of the 'brokers' element.
%% {broker, "amqp://"},
%% {declarations, []}
%% ]},
%% Name of the queue to shovel messages from.
%%
%% {queue, <<"your-queue-name-goes-here">>},
%% Optional prefetch count.
%%
%% {prefetch_count, 10},
%% when to acknowledge messages:
%% - no_ack: never (auto)
%% - on_publish: after each message is republished
%% - on_confirm: when the destination broker confirms receipt
%%
%% {ack_mode, on_confirm},
%% Overwrite fields of the outbound basic.publish.
%%
%% {publish_fields, [{exchange, <<"my_exchange">>},
%% {routing_key, <<"from_shovel">>}]},
%% Static list of basic.properties to set on re-publication.
%%
%% {publish_properties, [{delivery_mode, 2}]},
%% The number of seconds to wait before attempting to
%% reconnect in the event of a connection failure.
%%
%% {reconnect_delay, 2.5}
%% ]} %% End of my_first_shovel
]}
%% Rather than specifying some values per-shovel, you can specify
%% them for all shovels here.
%%
%% {defaults, [{prefetch_count, 0},
%% {ack_mode, on_confirm},
%% {publish_fields, []},
%% {publish_properties, [{delivery_mode, 2}]},
%% {reconnect_delay, 2.5}]}
]},
%% ----------------------------------------------------------------------------
%% RabbitMQ Stomp Adapter
%%
%% See http://www.rabbitmq.com/stomp.html for details
%% ----------------------------------------------------------------------------
{rabbitmq_stomp,
[%% Network Configuration - the format is generally the same as for the broker
%% Listen only on localhost (ipv4 & ipv6) on a specific port.
%% {tcp_listeners, [{"127.0.0.1", 61613},
%% {"::1", 61613}]},
%% Listen for SSL connections on a specific port.
%% {ssl_listeners, [61614]},
%% Number of Erlang processes that will accept connections for the TCP
%% and SSL listeners.
%%
%% {num_tcp_acceptors, 10},
%% {num_ssl_acceptors, 1},
%% Additional SSL options
%% Extract a name from the client's certificate when using SSL.
%%
%% {ssl_cert_login, true},
%% Set a default user name and password. This is used as the default login
%% whenever a CONNECT frame omits the login and passcode headers.
%%
%% Please note that setting this will allow clients to connect without
%% authenticating!
%%
%% {default_user, [{login, "guest"},
%% {passcode, "guest"}]},
%% If a default user is configured, or you have configured use SSL client
%% certificate based authentication, you can choose to allow clients to
%% omit the CONNECT frame entirely. If set to true, the client is
%% automatically connected as the default user or user supplied in the
%% SSL certificate whenever the first frame sent on a session is not a
%% CONNECT frame.
%%
%% {implicit_connect, true}
]},
%% ----------------------------------------------------------------------------
%% RabbitMQ MQTT Adapter
%%
%% See https://github.com/rabbitmq/rabbitmq-mqtt/blob/stable/README.md
%% for details
%% ----------------------------------------------------------------------------
{rabbitmq_mqtt,
[%% Set the default user name and password. Will be used as the default login
%% if a connecting client provides no other login details.
%%
%% Please note that setting this will allow clients to connect without
%% authenticating!
%%
%% {default_user, <<"guest">>},
%% {default_pass, <<"guest">>},
%% Enable anonymous access. If this is set to false, clients MUST provide
%% login information in order to connect. See the default_user/default_pass
%% configuration elements for managing logins without authentication.
%%
%% {allow_anonymous, true},
%% If you have multiple chosts, specify the one to which the
%% adapter connects.
%%
%% {vhost, <<"/">>},
%% Specify the exchange to which messages from MQTT clients are published.
%%
%% {exchange, <<"amq.topic">>},
%% Specify TTL (time to live) to control the lifetime of non-clean sessions.
%%
%% {subscription_ttl, 1800000},
%% Set the prefetch count (governing the maximum number of unacknowledged
%% messages that will be delivered).
%%
%% {prefetch, 10},
%% TCP/SSL Configuration (as per the broker configuration).
%%
%% {tcp_listeners, [1883]},
%% {ssl_listeners, []},
%% Number of Erlang processes that will accept connections for the TCP
%% and SSL listeners.
%%
%% {num_tcp_acceptors, 10},
%% {num_ssl_acceptors, 1},
%% TCP/Socket options (as per the broker configuration).
%%
%% {tcp_listen_options, [{backlog, 128},
%% {nodelay, true}]}
]},
%% ----------------------------------------------------------------------------
%% RabbitMQ AMQP 1.0 Support
%%
%% See https://github.com/rabbitmq/rabbitmq-amqp1.0/blob/stable/README.md
%% for details
%% ----------------------------------------------------------------------------
{rabbitmq_amqp1_0,
[%% Connections that are not authenticated with SASL will connect as this
%% account. See the README for more information.
%%
%% Please note that setting this will allow clients to connect without
%% authenticating!
%%
%% {default_user, "guest"},
%% Enable protocol strict mode. See the README for more information.
%%
%% {protocol_strict_mode, false}
]},
%% ----------------------------------------------------------------------------
%% RabbitMQ LDAP Plugin
%%
%% See http://www.rabbitmq.com/ldap.html for details.
%%
%% ----------------------------------------------------------------------------
{rabbitmq_auth_backend_ldap,
[%%
%% Connecting to the LDAP server(s)
%% ================================
%%
%% Specify servers to bind to. You *must* set this in order for the plugin
%% to work properly.
%%
%% {servers, ["your-server-name-goes-here"]},
%% Connect to the LDAP server using SSL
%%
%% {use_ssl, false},
%% Specify the LDAP port to connect to
%%
%% {port, 389},
%% LDAP connection timeout, in milliseconds or 'infinity'
%%
%% {timeout, infinity},
%% Enable logging of LDAP queries.
%% One of
%% - false (no logging is performed)
%% - true (verbose logging of the logic used by the plugin)
%% - network (as true, but additionally logs LDAP network traffic)
%%
%% Defaults to false.
%%
%% {log, false},
%%
%% Authentication
%% ==============
%%
%% Pattern to convert the username given through AMQP to a DN before
%% binding
%%
%% {user_dn_pattern, "cn=${username},ou=People,dc=example,dc=com"},
%% Alternatively, you can convert a username to a Distinguished
%% Name via an LDAP lookup after binding. See the documentation for
%% full details.
%% When converting a username to a dn via a lookup, set these to
%% the name of the attribute that represents the user name, and the
%% base DN for the lookup query.
%%
%% {dn_lookup_attribute, "userPrincipalName"},
%% {dn_lookup_base, "DC=gopivotal,DC=com"},
%% Controls how to bind for authorisation queries and also to
%% retrieve the details of users logging in without presenting a
%% password (e.g., SASL EXTERNAL).
%% One of
%% - as_user (to bind as the authenticated user - requires a password)
%% - anon (to bind anonymously)
%% - {UserDN, Password} (to bind with a specified user name and password)
%%
%% Defaults to 'as_user'.
%%
%% {other_bind, as_user},
%%
%% Authorisation
%% =============
%%
%% The LDAP plugin can perform a variety of queries against your
%% LDAP server to determine questions of authorisation. See
%% http://www.rabbitmq.com/ldap.html#authorisation for more
%% information.
%% Set the query to use when determining vhost access
%%
%% {vhost_access_query, {in_group,
%% "ou=${vhost}-users,ou=vhosts,dc=example,dc=com"}},
%% Set the query to use when determining resource (e.g., queue) access
%%
%% {resource_access_query, {constant, true}},
%% Set queries to determine which tags a user has
%%
%% {tag_queries, []}
]}
].
5、Golang调用RabbitMQ的案例
下载Golgang运行amqp协议的包，在Rabbitmq官网上有提供现在的golang包来使用amqp协议与Rabbitmq交互 。
我们先将包下载到本地,然后就可以直接使用了：
lion@node1:~$ go get github.com/streadway/amqp
5.1、使用Golang来发送第一个hello idoall.org
在第一个教程中，我们写程序从一个命名的队列(test-idoall-queues)中发送和接收消息。
producer_hello.go(消息生产者):
package main
import (
"fmt"
"log"
"github.com/streadway/amqp"
)
const (
//AMQP URI
uri = "amqp://guest:guest@localhost:5672/"
//Durable AMQP exchange name
exchangeName = ""
//Durable AMQP queue name
queueName = "test-idoall-queues"
//Body of message
bodyMsg string = "hello idoall.org"
)
//如果存在错误，则输出
func failOnError(err error, msg string) {
if err != nil {
log.Fatalf("%s: %s", msg, err)
panic(fmt.Sprintf("%s: %s", msg, err))
}
}
func main(){
//调用发布消息函数
publish(uri, exchangeName, queueName, bodyMsg)
log.Printf("published %dB OK", len(bodyMsg))
}
//发布者的方法
//
//@amqpURI, amqp的地址
//@exchange, exchange的名称
//@queue, queue的名称
//@body, 主体内容
func publish(amqpURI string, exchange string, queue string, body string){
//建立连接
log.Printf("dialing %q", amqpURI)
connection, err := amqp.Dial(amqpURI)
failOnError(err, "Failed to connect to RabbitMQ")
defer connection.Close()
//创建一个Channel
log.Printf("got Connection, getting Channel")
channel, err := connection.Channel()
failOnError(err, "Failed to open a channel")
defer channel.Close()
log.Printf("got queue, declaring %q", queue)
//创建一个queue
q, err := channel.QueueDeclare(
queueName, // name
false, // durable
false, // delete when unused
false, // exclusive
false, // no-wait
nil, // arguments
)
failOnError(err, "Failed to declare a queue")
log.Printf("declared queue, publishing %dB body (%q)", len(body), body)
// Producer只能发送到exchange，它是不能直接发送到queue的。
// 现在我们使用默认的exchange（名字是空字符）。这个默认的exchange允许我们发送给指定的queue。
// routing_key就是指定的queue名字。
err = channel.Publish(
exchange, // exchange
q.Name, // routing key
false, // mandatory
false, // immediate
amqp.Publishing {
Headers: amqp.Table{},
ContentType: "text/plain",
ContentEncoding: "",
Body: []byte(body),
})
failOnError(err, "Failed to publish a message")
}
consumer_hello(消息消费者).go
package main
import (
"fmt"
"log"
"github.com/streadway/amqp"
)
const (
//AMQP URI
uri = "amqp://guest:guest@localhost:5672/"
//Durable AMQP exchange nam
exchangeName = ""
//Durable AMQP queue name
queueName = "test-idoall-queues"
)
//如果存在错误，则输出
func failOnError(err error, msg string) {
if err != nil {
log.Fatalf("%s: %s", msg, err)
panic(fmt.Sprintf("%s: %s", msg, err))
}
}
func main(){
//调用消息接收者
consumer(uri, exchangeName, queueName)
}
//接收者方法
//
//@amqpURI, amqp的地址
//@exchange, exchange的名称
//@queue, queue的名称
func consumer(amqpURI string, exchange string, queue string){
//建立连接
log.Printf("dialing %q", amqpURI)
connection, err := amqp.Dial(amqpURI)
failOnError(err, "Failed to connect to RabbitMQ")
defer connection.Close()
//创建一个Channel
log.Printf("got Connection, getting Channel")
channel, err := connection.Channel()
failOnError(err, "Failed to open a channel")
defer channel.Close()
log.Printf("got queue, declaring %q", queue)
//创建一个queue
q, err := channel.QueueDeclare(
queueName, // name
false, // durable
false, // delete when unused
false, // exclusive
false, // no-wait
nil, // arguments
)
failOnError(err, "Failed to declare a queue")
log.Printf("Queue bound to Exchange, starting Consume")
//订阅消息
msgs, err := channel.Consume(
q.Name, // queue
"", // consumer
true, // auto-ack
false, // exclusive
false, // no-local
false, // no-wait
nil, // args
)
failOnError(err, "Failed to register a consumer")
//创建一个channel
forever := make(chan bool)
//调用gorountine
go func() {
for d := range msgs {
log.Printf("Received a message: %s", d.Body)
}
}()
log.Printf(" [*] Waiting for messages. To exit press CTRL+C")
//没有写入数据，一直等待读，阻塞当前线程，目的是让线程不退出
<-forever
}
Console1(运行producer)：
lion@node1:~/_code/_rabbitmq/_golang$ go run producer_hello.go
2016/07/23 02:29:51 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 02:29:51 got Connection, getting Channel
2016/07/23 02:29:51 got queue, declaring "test-idoall-queues"
2016/07/23 02:29:51 declared queue, publishing 16B body ("hello idoall.org")
2016/07/23 02:29:51 published 16B OK
然后运行以下命令，可以看到我们刚才创建的queues在列表中
lion@node1:~/_code/_rabbitmq/_golang$ rabbitmqctl list_queues
Listing queues ...
test-idoall-queues 1
Console2(运行consumer)打印消息到屏幕，可以看到刚才我们通过producer发送的消息hello idoall.org
lion@node1:~/_code/_rabbitmq/_golang$ go run consumer_hello.go
2016/07/23 03:33:14 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 03:33:14 got Connection, getting Channel
2016/07/23 03:33:14 got queue, declaring "test-idoall-queues"
2016/07/23 03:33:14 Queue bound to Exchange, starting Consume
2016/07/23 03:33:14 [*] Waiting for messages. To exit press CTRL+C
2016/07/23 03:33:14 Received a message: hello idoall.org
5.2、Rabbitmq的任务分发机制
在5.1章节中，我们写程序从一个命名的队列中发送和接收消息。在这个章节中，我们将创建一个工作队列，将用于分配在多个工人之间的耗时的任务。
RabbitMQ的分发机制非常适合扩展，而且它是专门为并发程序设计的。如果任务队伍过多，那么只需要创建更多的Consumer来进行任务处理即可。
producer_task.go（消息生产者）:
package main
import (
"fmt"
"log"
"os"
"strings"
"github.com/streadway/amqp"
)
const (
//AMQP URI
uri = "amqp://guest:guest@localhost:5672/"
//Durable AMQP exchange name
exchangeName = ""
//Durable AMQP queue name
queueName = "test-idoall-queues-task"
)
//如果存在错误，则输出
func failOnError(err error, msg string) {
if err != nil {
log.Fatalf("%s: %s", msg, err)
panic(fmt.Sprintf("%s: %s", msg, err))
}
}
func main(){
bodyMsg := bodyFrom(os.Args)
//调用发布消息函数
publish(uri, exchangeName, queueName, bodyMsg)
log.Printf("published %dB OK", len(bodyMsg))
}
func bodyFrom(args []string) string {
var s string
if (len(args) < 2) || os.Args[1] == "" {
s = "hello idoall.org"
} else {
s = strings.Join(args[1:], " ")
}
return s
}
//发布者的方法
//
//@amqpURI, amqp的地址
//@exchange, exchange的名称
//@queue, queue的名称
//@body, 主体内容
func publish(amqpURI string, exchange string, queue string, body string){
//建立连接
log.Printf("dialing %q", amqpURI)
connection, err := amqp.Dial(amqpURI)
failOnError(err, "Failed to connect to RabbitMQ")
defer connection.Close()
//创建一个Channel
log.Printf("got Connection, getting Channel")
channel, err := connection.Channel()
failOnError(err, "Failed to open a channel")
defer channel.Close()
log.Printf("got queue, declaring %q", queue)
//创建一个queue
q, err := channel.QueueDeclare(
queueName, // name
false, // durable
false, // delete when unused
false, // exclusive
false, // no-wait
nil, // arguments
)
failOnError(err, "Failed to declare a queue")
log.Printf("declared queue, publishing %dB body (%q)", len(body), body)
// Producer只能发送到exchange，它是不能直接发送到queue的。
// 现在我们使用默认的exchange（名字是空字符）。这个默认的exchange允许我们发送给指定的queue。
// routing_key就是指定的queue名字。
err = channel.Publish(
exchange, // exchange
q.Name, // routing key
false, // mandatory
false, // immediate
amqp.Publishing {
Headers: amqp.Table{},
ContentType: "text/plain",
ContentEncoding: "",
Body: []byte(body),
})
failOnError(err, "Failed to publish a message")
}
consumer_task（消息消费者）.go
package main
import (
"fmt"
"log"
"bytes"
"time"
"github.com/streadway/amqp"
)
const (
//AMQP URI
uri = "amqp://guest:guest@localhost:5672/"
//Durable AMQP exchange nam
exchangeName = ""
//Durable AMQP queue name
queueName = "test-idoall-queues-task"
)
//如果存在错误，则输出
func failOnError(err error, msg string) {
if err != nil {
log.Fatalf("%s: %s", msg, err)
panic(fmt.Sprintf("%s: %s", msg, err))
}
}
func main(){
//调用消息接收者
consumer(uri, exchangeName, queueName)
}
//接收者方法
//
//@amqpURI, amqp的地址
//@exchange, exchange的名称
//@queue, queue的名称
func consumer(amqpURI string, exchange string, queue string){
//建立连接
log.Printf("dialing %q", amqpURI)
connection, err := amqp.Dial(amqpURI)
failOnError(err, "Failed to connect to RabbitMQ")
defer connection.Close()
//创建一个Channel
log.Printf("got Connection, getting Channel")
channel, err := connection.Channel()
failOnError(err, "Failed to open a channel")
defer channel.Close()
log.Printf("got queue, declaring %q", queue)
//创建一个queue
q, err := channel.QueueDeclare(
queueName, // name
false, // durable
false, // delete when unused
false, // exclusive
false, // no-wait
nil, // arguments
)
failOnError(err, "Failed to declare a queue")
log.Printf("Queue bound to Exchange, starting Consume")
//订阅消息
msgs, err := channel.Consume(
q.Name, // queue
"", // consumer
false, // auto-ack
false, // exclusive
false, // no-local
false, // no-wait
nil, // args
)
failOnError(err, "Failed to register a consumer")
//创建一个channel
forever := make(chan bool)
//调用gorountine
go func() {
for d := range msgs {
log.Printf("Received a message: %s", d.Body)
dot_count := bytes.Count(d.Body, []byte("."))
t := time.Duration(dot_count)
time.Sleep(t * time.Second)
log.Printf("Done")
}
}()
log.Printf(" [*] Waiting for messages. To exit press CTRL+C")
//没有写入数据，一直等待读，阻塞当前线程，目的是让线程不退出
<-forever
}
查看结果
Console1(consumer)：
lion@node1:~/_code/_rabbitmq/_golang$ go run consumer_task.go
2016/07/23 10:11:40 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 10:11:40 got Connection, getting Channel
2016/07/23 10:11:40 got queue, declaring "test-idoall-queues-task"
2016/07/23 10:11:40 Queue bound to Exchange, starting Consume
2016/07/23 10:11:40 [*] Waiting for messages. To exit press CTRL+C
Console2(consumer)：
lion@node1:~/_code/_rabbitmq/_golang$ go run consumer_task.go
2016/07/23 10:11:40 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 10:11:40 got Connection, getting Channel
2016/07/23 10:11:40 got queue, declaring "test-idoall-queues-task"
2016/07/23 10:11:40 Queue bound to Exchange, starting Consume
2016/07/23 10:11:40 [*] Waiting for messages. To exit press CTRL+C
这个时候我们使用Producer 来 Publish Message：
lion@node1:~/_code/_rabbitmq/_golang$ go run producer_task.go First message. && go run producer_task.go Second message.. && go run producer_task.go Third message... && go run producer_task.go Fourth message.... && go run producer_task.go Fifth message.....
2016/07/23 10:17:13 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 10:17:13 got Connection, getting Channel
2016/07/23 10:17:13 got queue, declaring "test-idoall-queues-task"
2016/07/23 10:17:13 declared queue, publishing 14B body ("First message.")
2016/07/23 10:17:13 published 14B OK
2016/07/23 10:17:14 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 10:17:14 got Connection, getting Channel
2016/07/23 10:17:14 got queue, declaring "test-idoall-queues-task"
2016/07/23 10:17:14 declared queue, publishing 16B body ("Second message..")
2016/07/23 10:17:14 published 16B OK
2016/07/23 10:17:15 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 10:17:15 got Connection, getting Channel
2016/07/23 10:17:15 got queue, declaring "test-idoall-queues-task"
2016/07/23 10:17:15 declared queue, publishing 16B body ("Third message...")
2016/07/23 10:17:15 published 16B OK
2016/07/23 10:17:16 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 10:17:16 got Connection, getting Channel
2016/07/23 10:17:16 got queue, declaring "test-idoall-queues-task"
2016/07/23 10:17:16 declared queue, publishing 18B body ("Fourth message....")
2016/07/23 10:17:16 published 18B OK
2016/07/23 10:17:16 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 10:17:16 got Connection, getting Channel
2016/07/23 10:17:16 got queue, declaring "test-idoall-queues-task"
2016/07/23 10:17:16 declared queue, publishing 18B body ("Fifth message.....")
2016/07/23 10:17:16 published 18B OK
这时我们再看刚才打开的两个Consumer的结果：
Console1(consumer)：
lion@node1:~/_code/_rabbitmq/_golang$ go run consumer_task.go
2016/07/23 10:11:21 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 10:11:21 got Connection, getting Channel
2016/07/23 10:11:21 got queue, declaring "test-idoall-queues-task"
2016/07/23 10:11:21 Queue bound to Exchange, starting Consume
2016/07/23 10:11:21 [*] Waiting for messages. To exit press CTRL+C
2016/07/23 10:17:13 Received a message: First message.
2016/07/23 10:17:14 Done
2016/07/23 10:17:15 Received a message: Third message...
2016/07/23 10:17:18 Done
2016/07/23 10:17:18 Received a message: Fifth message.....
2016/07/23 10:17:23 Done
Console2(consumer)：
lion@node1:~/_code/_rabbitmq/_golang$ go run consumer_task.go
2016/07/23 10:11:40 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 10:11:40 got Connection, getting Channel
2016/07/23 10:11:40 got queue, declaring "test-idoall-queues-task"
2016/07/23 10:11:40 Queue bound to Exchange, starting Consume
2016/07/23 10:11:40 [*] Waiting for messages. To exit press CTRL+C
2016/07/23 10:17:14 Received a message: Second message..
2016/07/23 10:17:16 Done
2016/07/23 10:17:16 Received a message: Fourth message....
2016/07/23 10:17:20 Done
默认情况下，RabbitMQ 会顺序的分发每个Message。当每个收到ack后，会将该Message删除，然后将下一个Message分发到下一个Consumer。这种分发方式叫做round-robin，也叫消息轮询
5.3、Message acknowledgment 消息确认
每个Consumer可能需要一段时间才能处理完收到的数据。如果在这个过程中，Consumer出错了，异常退出了，而数据还没有处理完成，那么非常不幸，这段数据就丢失了。因为我们的代码，一旦RabbitMQ Server发送给Consumer消息后，会立即把这个Message标记为完成，然后从queue中删除。我们将无法再操作这个尚未处理完成的消息。
实际场景中，如果一个Consumer异常退出了，我们希望它处理的数据能够被另外的Consumer处理，这样数据在这种情况下（通道关闭、连接关闭、TCP连接丢失等情况）就不会丢失了。
为了保证数据不被丢失，RabbitMQ支持消息确认机制，ack(nowledgments)是从Consumer消费后发送到一个特定的消息告诉RabbitMQ已经收到、处理结束，RabbitMQ可以去安全的删除它了。
如果Consumer退出了但是没有发送ack，那么RabbitMQ就会把这个Message重新排进队列，发送到下一个Consumer。这样就保证了在Consumer异常退出的情况下数据也不会丢失。
这里并没有用到超时机制。RabbitMQ仅仅通过Consumer的连接中断来确认该Message并没有被正确处理。也就是说，RabbitMQ给了Consumer足够长的时间来做数据处理。
消息确认默认是关闭的，我们需要通过，d.ACK(false)来告诉RabbitMQ我们已经完成任务。
producer_acknowledgments(消息生产者).go:
package main
import (
"fmt"
"log"
"os"
"strings"
"github.com/streadway/amqp"
)
const (
//AMQP URI
uri = "amqp://guest:guest@localhost:5672/"
//Durable AMQP exchange name
exchangeName = ""
//Durable AMQP queue name
queueName = "test-idoall-queues-acknowledgments"
)
//如果存在错误，则输出
func failOnError(err error, msg string) {
if err != nil {
log.Fatalf("%s: %s", msg, err)
panic(fmt.Sprintf("%s: %s", msg, err))
}
}
func main(){
bodyMsg := bodyFrom(os.Args)
//调用发布消息函数
publish(uri, exchangeName, queueName, bodyMsg)
log.Printf("published %dB OK", len(bodyMsg))
}
func bodyFrom(args []string) string {
var s string
if (len(args) < 2) || os.Args[1] == "" {
s = "hello idoall.org"
} else {
s = strings.Join(args[1:], " ")
}
return s
}
//发布者的方法
//
//@amqpURI, amqp的地址
//@exchange, exchange的名称
//@queue, queue的名称
//@body, 主体内容
func publish(amqpURI string, exchange string, queue string, body string){
//建立连接
log.Printf("dialing %q", amqpURI)
connection, err := amqp.Dial(amqpURI)
failOnError(err, "Failed to connect to RabbitMQ")
defer connection.Close()
//创建一个Channel
log.Printf("got Connection, getting Channel")
channel, err := connection.Channel()
failOnError(err, "Failed to open a channel")
defer channel.Close()
log.Printf("got queue, declaring %q", queue)
//创建一个queue
q, err := channel.QueueDeclare(
queueName, // name
false, // durable
false, // delete when unused
false, // exclusive
false, // no-wait
nil, // arguments
)
failOnError(err, "Failed to declare a queue")
log.Printf("declared queue, publishing %dB body (%q)", len(body), body)
// Producer只能发送到exchange，它是不能直接发送到queue的。
// 现在我们使用默认的exchange（名字是空字符）。这个默认的exchange允许我们发送给指定的queue。
// routing_key就是指定的queue名字。
err = channel.Publish(
exchange, // exchange
q.Name, // routing key
false, // mandatory
false, // immediate
amqp.Publishing {
Headers: amqp.Table{},
ContentType: "text/plain",
ContentEncoding: "",
Body: []byte(body),
})
failOnError(err, "Failed to publish a message")
}
consumer_acknowledgments（消息消费者）.go
package main
import (
"fmt"
"log"
"bytes"
"time"
"github.com/streadway/amqp"
)
const (
//AMQP URI
uri = "amqp://guest:guest@localhost:5672/"
//Durable AMQP exchange nam
exchangeName = ""
//Durable AMQP queue name
queueName = "test-idoall-queues-acknowledgments"
)
//如果存在错误，则输出
func failOnError(err error, msg string) {
if err != nil {
log.Fatalf("%s: %s", msg, err)
panic(fmt.Sprintf("%s: %s", msg, err))
}
}
func main(){
//调用消息接收者
consumer(uri, exchangeName, queueName)
}
//接收者方法
//
//@amqpURI, amqp的地址
//@exchange, exchange的名称
//@queue, queue的名称
func consumer(amqpURI string, exchange string, queue string){
//建立连接
log.Printf("dialing %q", amqpURI)
connection, err := amqp.Dial(amqpURI)
failOnError(err, "Failed to connect to RabbitMQ")
defer connection.Close()
//创建一个Channel
log.Printf("got Connection, getting Channel")
channel, err := connection.Channel()
failOnError(err, "Failed to open a channel")
defer channel.Close()
log.Printf("got queue, declaring %q", queue)
//创建一个queue
q, err := channel.QueueDeclare(
queueName, // name
false, // durable
false, // delete when unused
false, // exclusive
false, // no-wait
nil, // arguments
)
failOnError(err, "Failed to declare a queue")
log.Printf("Queue bound to Exchange, starting Consume")
//订阅消息
msgs, err := channel.Consume(
q.Name, // queue
"", // consumer
false, // auto-ack
false, // exclusive
false, // no-local
false, // no-wait
nil, // args
)
failOnError(err, "Failed to register a consumer")
//创建一个channel
forever := make(chan bool)
//调用gorountine
go func() {
for d := range msgs {
log.Printf("Received a message: %s", d.Body)
dot_count := bytes.Count(d.Body, []byte("."))
t := time.Duration(dot_count)
time.Sleep(t * time.Second)
log.Printf("Done")
d.Ack(false)
}
}()
log.Printf(" [*] Waiting for messages. To exit press CTRL+C")
//没有写入数据，一直等待读，阻塞当前线程，目的是让线程不退出
<-forever
}
查看结果
我们先使用Producer来发送一列消息：
lion@node1:~/_code/_rabbitmq/_golang$ go run producer_acknowledgments.go First message. && go run producer_acknowledgments.go Second message.. && go run producer_acknowledgments.go Third message... && go run producer_acknowledgments.go Fourth message.... && go run producer_acknowledgments.go Fifth message.....
2016/07/23 21:41:40 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 21:41:40 got Connection, getting Channel
2016/07/23 21:41:40 got queue, declaring "test-idoall-queues-acknowledgments"
2016/07/23 21:41:40 declared queue, publishing 14B body ("First message.")
2016/07/23 21:41:40 published 14B OK
2016/07/23 21:41:41 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 21:41:41 got Connection, getting Channel
2016/07/23 21:41:41 got queue, declaring "test-idoall-queues-acknowledgments"
2016/07/23 21:41:41 declared queue, publishing 16B body ("Second message..")
2016/07/23 21:41:41 published 16B OK
2016/07/23 21:41:41 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 21:41:41 got Connection, getting Channel
2016/07/23 21:41:41 got queue, declaring "test-idoall-queues-acknowledgments"
2016/07/23 21:41:41 declared queue, publishing 16B body ("Third message...")
2016/07/23 21:41:41 published 16B OK
2016/07/23 21:41:42 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 21:41:42 got Connection, getting Channel
2016/07/23 21:41:42 got queue, declaring "test-idoall-queues-acknowledgments"
2016/07/23 21:41:42 declared queue, publishing 18B body ("Fourth message....")
2016/07/23 21:41:42 published 18B OK
2016/07/23 21:41:43 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 21:41:43 got Connection, getting Channel
2016/07/23 21:41:43 got queue, declaring "test-idoall-queues-acknowledgments"
2016/07/23 21:41:43 declared queue, publishing 18B body ("Fifth message.....")
2016/07/23 21:41:43 published 18B OK
通过rabbitmqctl命令，来看下messages_unacknowledged的情况：
lion@node1:~/_code/_rabbitmq/_golang$ rabbitmqctl list_queues name messages_ready messages_unacknowledged
Listing queues ...
test-idoall-queues-task 0 0
test-idoall-queues 0 0
test-idoall-queues-acknowledgments 5 0
使用Consumer来订阅消息操作到第三条的时候，我们按CTRL+C退出，这个时候相当于消息已经被读取，但是未发送d.ACK(false)：
lion@node1:~/_code/_rabbitmq/_golang$ go run consumer_acknowledgments.go
2016/07/23 21:56:35 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 21:56:35 got Connection, getting Channel
2016/07/23 21:56:35 got queue, declaring "test-idoall-queues-acknowledgments"
2016/07/23 21:56:35 Queue bound to Exchange, starting Consume
2016/07/23 21:56:35 [*] Waiting for messages. To exit press CTRL+C
2016/07/23 21:56:35 Received a message: First message.
2016/07/23 21:56:36 Done
2016/07/23 21:56:36 Received a message: Second message..
2016/07/23 21:56:38 Done
2016/07/23 21:56:38 Received a message: Third message...
^Csignal: interrupt
再通过rabbitmqctl命令可以看到，还是有3条消息未处理
lion@node1:~/_code/_rabbitmq/_golang$ rabbitmqctl list_queues name messages_ready messages_unacknowledged
Listing queues ...
test-idoall-queues-task 0 0
test-idoall-queues 0 0
test-idoall-queues-acknowledgments 3 0
5.4、Message durability消息持久化
如果服务器死机或程序 crash了，数据仍然会丢失。为了确保消息不会丢失，我们需要将queue和Message做持久化操作。
将durable设置为true可以做持久化处理（生产者和消息者的代码里都要设置），如果是已经存在的一个queue 没有设置过持久化，再重新设置是不起作用的，我们需要重新为queue设置一个名字。
最后在Producer发布消息的时候，我们需要设置DeliveryMode为amqp.Persistent，持久化的工作就做完了，下面我们来看代码
producer_durability.go（消息生产者）:
package main
import (
"fmt"
"log"
"os"
"strings"
"github.com/streadway/amqp"
)
const (
//AMQP URI
uri = "amqp://guest:guest@localhost:5672/"
//Durable AMQP exchange name
exchangeName = ""
//Durable AMQP queue name
queueName = "test-idoall-queues-durability"
)
//如果存在错误，则输出
func failOnError(err error, msg string) {
if err != nil {
log.Fatalf("%s: %s", msg, err)
panic(fmt.Sprintf("%s: %s", msg, err))
}
}
func main(){
bodyMsg := bodyFrom(os.Args)
//调用发布消息函数
publish(uri, exchangeName, queueName, bodyMsg)
log.Printf("published %dB OK", len(bodyMsg))
}
func bodyFrom(args []string) string {
var s string
if (len(args) < 2) || os.Args[1] == "" {
s = "hello idoall.org"
} else {
s = strings.Join(args[1:], " ")
}
return s
}
//发布者的方法
//
//@amqpURI, amqp的地址
//@exchange, exchange的名称
//@queue, queue的名称
//@body, 主体内容
func publish(amqpURI string, exchange string, queue string, body string){
//建立连接
log.Printf("dialing %q", amqpURI)
connection, err := amqp.Dial(amqpURI)
failOnError(err, "Failed to connect to RabbitMQ")
defer connection.Close()
//创建一个Channel
log.Printf("got Connection, getting Channel")
channel, err := connection.Channel()
failOnError(err, "Failed to open a channel")
defer channel.Close()
log.Printf("got queue, declaring %q", queue)
//创建一个queue
q, err := channel.QueueDeclare(
queueName, // name
true, // durable
false, // delete when unused
false, // exclusive
false, // no-wait
nil, // arguments
)
failOnError(err, "Failed to declare a queue")
log.Printf("declared queue, publishing %dB body (%q)", len(body), body)
// Producer只能发送到exchange，它是不能直接发送到queue的。
// 现在我们使用默认的exchange（名字是空字符）。这个默认的exchange允许我们发送给指定的queue。
// routing_key就是指定的queue名字。
err = channel.Publish(
exchange, // exchange
q.Name, // routing key
false, // mandatory
false, // immediate
amqp.Publishing {
Headers: amqp.Table{},
DeliveryMode: amqp.Persistent,
ContentType: "text/plain",
ContentEncoding: "",
Body: []byte(body),
})
failOnError(err, "Failed to publish a message")
}
consumer_durability.go（消息接收者）：
package main
import (
"fmt"
"log"
"bytes"
"time"
"github.com/streadway/amqp"
)
const (
//AMQP URI
uri = "amqp://guest:guest@localhost:5672/"
//Durable AMQP exchange nam
exchangeName = ""
//Durable AMQP queue name
queueName = "test-idoall-queues-durability"
)
//如果存在错误，则输出
func failOnError(err error, msg string) {
if err != nil {
log.Fatalf("%s: %s", msg, err)
panic(fmt.Sprintf("%s: %s", msg, err))
}
}
func main(){
//调用消息接收者
consumer(uri, exchangeName, queueName)
}
//接收者方法
//
//@amqpURI, amqp的地址
//@exchange, exchange的名称
//@queue, queue的名称
func consumer(amqpURI string, exchange string, queue string){
//建立连接
log.Printf("dialing %q", amqpURI)
connection, err := amqp.Dial(amqpURI)
failOnError(err, "Failed to connect to RabbitMQ")
defer connection.Close()
//创建一个Channel
log.Printf("got Connection, getting Channel")
channel, err := connection.Channel()
failOnError(err, "Failed to open a channel")
defer channel.Close()
log.Printf("got queue, declaring %q", queue)
//创建一个queue
q, err := channel.QueueDeclare(
queueName, // name
true, // durable
false, // delete when unused
false, // exclusive
false, // no-wait
nil, // arguments
)
failOnError(err, "Failed to declare a queue")
log.Printf("Queue bound to Exchange, starting Consume")
//订阅消息
msgs, err := channel.Consume(
q.Name, // queue
"", // consumer
false, // auto-ack
false, // exclusive
false, // no-local
false, // no-wait
nil, // args
)
failOnError(err, "Failed to register a consumer")
//创建一个channel
forever := make(chan bool)
//调用gorountine
go func() {
for d := range msgs {
log.Printf("Received a message: %s", d.Body)
dot_count := bytes.Count(d.Body, []byte("."))
t := time.Duration(dot_count)
time.Sleep(t * time.Second)
log.Printf("Done")
d.Ack(false)
}
}()
log.Printf(" [*] Waiting for messages. To exit press CTRL+C")
//没有写入数据，一直等待读，阻塞当前线程，目的是让线程不退出
<-forever
}
查看结果
我们先使用Producer来发送一列消息：
lion@node1:~/_code/_rabbitmq/_golang$ go run producer_durability.go First message. && go run producer_durability.go Second message.. && go run producer_durability.go Third message... && go run producer_durability.go Fourth message.... && go run producer_durability.go Fifth message.....
2016/07/23 22:35:03 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 22:35:03 got Connection, getting Channel
2016/07/23 22:35:03 got queue, declaring "test-idoall-queues-durability"
2016/07/23 22:35:04 declared queue, publishing 14B body ("First message.")
2016/07/23 22:35:04 published 14B OK
2016/07/23 22:35:04 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 22:35:04 got Connection, getting Channel
2016/07/23 22:35:04 got queue, declaring "test-idoall-queues-durability"
2016/07/23 22:35:04 declared queue, publishing 16B body ("Second message..")
2016/07/23 22:35:04 published 16B OK
2016/07/23 22:35:05 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 22:35:05 got Connection, getting Channel
2016/07/23 22:35:05 got queue, declaring "test-idoall-queues-durability"
2016/07/23 22:35:05 declared queue, publishing 16B body ("Third message...")
2016/07/23 22:35:05 published 16B OK
2016/07/23 22:35:06 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 22:35:06 got Connection, getting Channel
2016/07/23 22:35:06 got queue, declaring "test-idoall-queues-durability"
2016/07/23 22:35:06 declared queue, publishing 18B body ("Fourth message....")
2016/07/23 22:35:06 published 18B OK
2016/07/23 22:35:06 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 22:35:06 got Connection, getting Channel
2016/07/23 22:35:06 got queue, declaring "test-idoall-queues-durability"
2016/07/23 22:35:06 declared queue, publishing 18B body ("Fifth message.....")
2016/07/23 22:35:06 published 18B OK
通过rabbitmqctl list_queues命令，来看下messages_unacknowledged的情况：
lion@node1:~/_code/_rabbitmq/_golang$ rabbitmqctl list_queues
Listing queues ...
test-idoall-queues-task 0
test-idoall-queues 0
test-idoall-queues-durability 5
test-idoall-queues-acknowledgments 0
重启RabbitMQ-Server
lion@node1:~/_code/_rabbitmq/_golang$ rabbitmqctl stop
lion@node1:~/_code/_rabbitmq/_golang$ rabbitmq-server
RabbitMQ 3.6.3. Copyright (C) 2007-2016 Pivotal Software, Inc.
## ## Licensed under the MPL. See http://www.rabbitmq.com/
## ##
########## Logs: /home/lion/_app/rabbitmq_server-3.6.3/var/log/rabbitmq/rabbit@node1.log
###### ## /home/lion/_app/rabbitmq_server-3.6.3/var/log/rabbitmq/rabbit@node1-sasl.log
##########
Starting broker...
completed with 6 plugins.
再次通过rabbitmqctl list_queues命令查看，可以看到消息是存在的，说明我们的持久化是成功的
lion@node1:~/_code/_rabbitmq/_golang$ rabbitmqctl list_queues
Listing queues ...
test-idoall-queues-durability 5
5.5、Fair dispatch 公平分发
上面的，分发机制不是那么优雅。默认状态下，RabbitMQ将第n个Message分发给第n个Consumer。当然n是取余后的。它不管Consumer是否还有unacked Message，只是按照这个默认机制进行分发。
那么如果有个Consumer工作比较重，那么就会导致有的Consumer基本没事可做，有的Consumer却是毫无休息的机会。
通过 ch.Qos 方法设置预读取消息prefetch count=1 。这样RabbitMQ就会使得每个Consumer在同一个时间点最多处理一个Message。换句话说，在接收到该Consumer的ack前，他它不会将新的Message分发给它。
producer_fair_dispatch.go（消息生产者）:
package main
import (
"fmt"
"log"
"os"
"strings"
"github.com/streadway/amqp"
)
const (
//AMQP URI
uri = "amqp://guest:guest@localhost:5672/"
//Durable AMQP exchange name
exchangeName = ""
//Durable AMQP queue name
queueName = "test-idoall-queues-fair_dispatch"
)
//如果存在错误，则输出
func failOnError(err error, msg string) {
if err != nil {
log.Fatalf("%s: %s", msg, err)
panic(fmt.Sprintf("%s: %s", msg, err))
}
}
func main(){
bodyMsg := bodyFrom(os.Args)
//调用发布消息函数
publish(uri, exchangeName, queueName, bodyMsg)
log.Printf("published %dB OK", len(bodyMsg))
}
func bodyFrom(args []string) string {
var s string
if (len(args) < 2) || os.Args[1] == "" {
s = "hello idoall.org"
} else {
s = strings.Join(args[1:], " ")
}
return s
}
//发布者的方法
//
//@amqpURI, amqp的地址
//@exchange, exchange的名称
//@queue, queue的名称
//@body, 主体内容
func publish(amqpURI string, exchange string, queue string, body string){
//建立连接
log.Printf("dialing %q", amqpURI)
connection, err := amqp.Dial(amqpURI)
failOnError(err, "Failed to connect to RabbitMQ")
defer connection.Close()
//创建一个Channel
log.Printf("got Connection, getting Channel")
channel, err := connection.Channel()
failOnError(err, "Failed to open a channel")
defer channel.Close()
log.Printf("got queue, declaring %q", queue)
//创建一个queue
q, err := channel.QueueDeclare(
queueName, // name
true, // durable
false, // delete when unused
false, // exclusive
false, // no-wait
nil, // arguments
)
failOnError(err, "Failed to declare a queue")
log.Printf("declared queue, publishing %dB body (%q)", len(body), body)
// Producer只能发送到exchange，它是不能直接发送到queue的。
// 现在我们使用默认的exchange（名字是空字符）。这个默认的exchange允许我们发送给指定的queue。
// routing_key就是指定的queue名字。
err = channel.Publish(
exchange, // exchange
q.Name, // routing key
false, // mandatory
false, // immediate
amqp.Publishing {
Headers: amqp.Table{},
DeliveryMode: amqp.Persistent,
ContentType: "text/plain",
ContentEncoding: "",
Body: []byte(body),
})
failOnError(err, "Failed to publish a message")
}
consumer_fair_dispatch.go（消息消费者）：
package main
import (
"fmt"
"log"
"bytes"
"time"
"github.com/streadway/amqp"
)
const (
//AMQP URI
uri = "amqp://guest:guest@localhost:5672/"
//Durable AMQP exchange nam
exchangeName = ""
//Durable AMQP queue name
queueName = "test-idoall-queues-fair_dispatch"
)
//如果存在错误，则输出
func failOnError(err error, msg string) {
if err != nil {
log.Fatalf("%s: %s", msg, err)
panic(fmt.Sprintf("%s: %s", msg, err))
}
}
func main(){
//调用消息接收者
consumer(uri, exchangeName, queueName)
}
//接收者方法
//
//@amqpURI, amqp的地址
//@exchange, exchange的名称
//@queue, queue的名称
func consumer(amqpURI string, exchange string, queue string){
//建立连接
log.Printf("dialing %q", amqpURI)
connection, err := amqp.Dial(amqpURI)
failOnError(err, "Failed to connect to RabbitMQ")
defer connection.Close()
//创建一个Channel
log.Printf("got Connection, getting Channel")
channel, err := connection.Channel()
failOnError(err, "Failed to open a channel")
defer channel.Close()
log.Printf("got queue, declaring %q", queue)
//创建一个queue
q, err := channel.QueueDeclare(
queueName, // name
true, // durable
false, // delete when unused
false, // exclusive
false, // no-wait
nil, // arguments
)
failOnError(err, "Failed to declare a queue")
//每次只取一条消息
err = channel.Qos(
1, // prefetch count
0, // prefetch size
false, // global
)
failOnError(err, "Failed to set QoS")
log.Printf("Queue bound to Exchange, starting Consume")
//订阅消息
msgs, err := channel.Consume(
q.Name, // queue
"", // consumer
false, // auto-ack
false, // exclusive
false, // no-local
false, // no-wait
nil, // args
)
failOnError(err, "Failed to register a consumer")
//创建一个channel
forever := make(chan bool)
//调用gorountine
go func() {
for d := range msgs {
log.Printf("Received a message: %s", d.Body)
dot_count := bytes.Count(d.Body, []byte("."))
t := time.Duration(dot_count)
time.Sleep(t * time.Second)
log.Printf("Done")
d.Ack(false)
}
}()
log.Printf(" [*] Waiting for messages. To exit press CTRL+C")
//没有写入数据，一直等待读，阻塞当前线程，目的是让线程不退出
<-forever
}
查看结果
我们先使用Producer来发送一列消息：
lion@node1:~/_code/_rabbitmq/_golang$ go run producer_fair_dispatch.go First message. && go run producer_fair_dispatch.go Second message.. && go run producer_fair_dispatch.go Third message... && go run producer_fair_dispatch.go Fourth message.... && go run producer_fair_dispatch.go Fifth message.....
2016/07/23 23:09:24 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 23:09:24 got Connection, getting Channel
2016/07/23 23:09:24 got queue, declaring "test-idoall-queues-fair_dispatch"
2016/07/23 23:09:24 declared queue, publishing 14B body ("First message.")
2016/07/23 23:09:24 published 14B OK
2016/07/23 23:09:24 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 23:09:24 got Connection, getting Channel
2016/07/23 23:09:24 got queue, declaring "test-idoall-queues-fair_dispatch"
2016/07/23 23:09:24 declared queue, publishing 16B body ("Second message..")
2016/07/23 23:09:24 published 16B OK
2016/07/23 23:09:25 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 23:09:25 got Connection, getting Channel
2016/07/23 23:09:25 got queue, declaring "test-idoall-queues-fair_dispatch"
2016/07/23 23:09:25 declared queue, publishing 16B body ("Third message...")
2016/07/23 23:09:25 published 16B OK
2016/07/23 23:09:26 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 23:09:26 got Connection, getting Channel
2016/07/23 23:09:26 got queue, declaring "test-idoall-queues-fair_dispatch"
2016/07/23 23:09:26 declared queue, publishing 18B body ("Fourth message....")
2016/07/23 23:09:26 published 18B OK
2016/07/23 23:09:27 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 23:09:27 got Connection, getting Channel
2016/07/23 23:09:27 got queue, declaring "test-idoall-queues-fair_dispatch"
2016/07/23 23:09:27 declared queue, publishing 18B body ("Fifth message.....")
2016/07/23 23:09:27 published 18B OK
再依次在两个Console中依次执行下面的命令，可以看到消息被正常的分发了
Console1（consumer）:
lion@node1:~/_code/_rabbitmq/_golang$ go run consumer_fair_dispatch.go
2016/07/23 23:10:47 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 23:10:47 got Connection, getting Channel
2016/07/23 23:10:47 got queue, declaring "test-idoall-queues-fair_dispatch"
2016/07/23 23:10:47 Queue bound to Exchange, starting Consume
2016/07/23 23:10:47 [*] Waiting for messages. To exit press CTRL+C
2016/07/23 23:10:47 Received a message: First message.
2016/07/23 23:10:48 Done
2016/07/23 23:10:48 Received a message: Second message..
2016/07/23 23:10:50 Done
2016/07/23 23:10:50 Received a message: Fourth message....
2016/07/23 23:10:54 Done
Console2（consumer）:
lion@node1:~/_code/_rabbitmq/_golang$ go run consumer_fair_dispatch.go
2016/07/23 23:10:49 dialing "amqp://guest:guest@localhost:5672/"
2016/07/23 23:10:49 got Connection, getting Channel
2016/07/23 23:10:49 got queue, declaring "test-idoall-queues-fair_dispatch"
2016/07/23 23:10:49 Queue bound to Exchange, starting Consume
2016/07/23 23:10:49 [*] Waiting for messages. To exit press CTRL+C
2016/07/23 23:10:49 Received a message: Third message...
2016/07/23 23:10:52 Done
2016/07/23 23:10:52 Received a message: Fifth message.....
2016/07/23 23:10:57 Done
基于AMQP的更多通道和消息属性，可以浏览AMQP API参考
5.6、Exchanges & Bindings
RabbitMQ 的Messaging Model就是Producer并不会直接发送Message到queue。实际上，Producer并不知道它发送的Message是否已经到达queue。
Producer发送的Message实际上是发到了Exchange中。它的功能也很简单：从Producer接收Message，然后投递到queue中。Exchange需要知道如何处理Message，是把它放到一个queue中，还是放到多个queue中？这个rule是通过Exchange 的类型定义的。
我们知道有三种类型的Exchange：direct,，topic，headers 和fanout。fanout就是广播模式，会将所有的Message都放到它所知道的queue中。
现在我们已经创建了fanout类型的exchange和没有名字的queue（实际上是RabbitMQ帮我们取了名字）。那exchange怎么样知道它的Message发送到哪个queue呢？答案就是通过bindings
通过rabbitmqctl可以列出当前所有的Exchange：
lion@node1:~/_code/_rabbitmq/_golang$ rabbitmqctl list_exchanges
Listing exchanges ...
amq.direct direct
amq.fanout fanout
amq.match headers
amq.headers headers
direct
amq.rabbitmq.trace topic
amq.topic topic
amq.rabbitmq.log topic
注意：amq.* 是RabbitMQ默认创建的。
我们假设做一个日志系统，其中一个运行的接收程序Consumer发到消息后写入到磁盘中，同时， 另一个Consumer将收到的日志输出到屏幕上。
producer_exchange_logs.go（消息生产者）:
package main
import (
"fmt"
"log"
"os"
"strings"
"github.com/streadway/amqp"
)
const (
//AMQP URI
uri = "amqp://guest:guest@localhost:5672/"
//Durable AMQP exchange name
exchangeName = "test-idoall-exchange-logs"
//Exchange type - direct|fanout|topic|x-custom
exchangeType = "fanout"
//AMQP routing key
routingKey = ""
)
//如果存在错误，则输出
func failOnError(err error, msg string) {
if err != nil {
log.Fatalf("%s: %s", msg, err)
panic(fmt.Sprintf("%s: %s", msg, err))
}
}
func main(){
bodyMsg := bodyFrom(os.Args)
//调用发布消息函数
publish(uri, exchangeName, exchangeType, routingKey, bodyMsg)
log.Printf("published %dB OK", len(bodyMsg))
}
func bodyFrom(args []string) string {
var s string
if (len(args) < 2) || os.Args[1] == "" {
s = "hello idoall.org"
} else {
s = strings.Join(args[1:], " ")
}
return s
}
//发布者的方法
//
//@amqpURI, amqp的地址
//@exchange, exchange的名称
//@exchangeType, exchangeType的类型direct|fanout|topic
//@routingKey, routingKey的名称
//@body, 主体内容
func publish(amqpURI string, exchange string, exchangeType string, routingKey string, body string){
//建立连接
log.Printf("dialing %q", amqpURI)
connection, err := amqp.Dial(amqpURI)
failOnError(err, "Failed to connect to RabbitMQ")
defer connection.Close()
//创建一个Channel
log.Printf("got Connection, getting Channel")
channel, err := connection.Channel()
failOnError(err, "Failed to open a channel")
defer channel.Close()
//创建一个queue
log.Printf("got Channel, declaring %q Exchange (%q)", exchangeType, exchange)
err = channel.ExchangeDeclare(
exchange, // name
exchangeType, // type
true, // durable
false, // auto-deleted
false, // internal
false, // noWait
nil, // arguments
)
failOnError(err, "Failed to declare a queue")
// 发布消息
log.Printf("declared queue, publishing %dB body (%q)", len(body), body)
err = channel.Publish(
exchange, // exchange
routingKey, // routing key
false, // mandatory
false, // immediate
amqp.Publishing {
Headers: amqp.Table{},
ContentType: "text/plain",
ContentEncoding: "",
Body: []byte(body),
})
failOnError(err, "Failed to publish a message")
}
consumer_exchange_logs.go（消息消费者）：
package main
import (
"fmt"
"log"
"github.com/streadway/amqp"
)
const (
//AMQP URI
uri = "amqp://guest:guest@localhost:5672/"
//Durable AMQP exchange name
exchangeName = "test-idoall-exchange-logs"
//Exchange type - direct|fanout|topic|x-custom
exchangeType = "fanout"
//AMQP binding key
bindingKey = ""
//Durable AMQP queue name
queueName = ""
)
//如果存在错误，则输出
func failOnError(err error, msg string) {
if err != nil {
log.Fatalf("%s: %s", msg, err)
panic(fmt.Sprintf("%s: %s", msg, err))
}
}
func main(){
//调用消息接收者
consumer(uri, exchangeName, exchangeType, queueName, bindingKey)
}
//接收者方法
//
//@amqpURI, amqp的地址
//@exchange, exchange的名称
//@exchangeType, exchangeType的类型direct|fanout|topic
//@queue, queue的名称
//@key , 绑定的key名称
func consumer(amqpURI string, exchange string, exchangeType string, queue string, key string){
//建立连接
log.Printf("dialing %q", amqpURI)
connection, err := amqp.Dial(amqpURI)
failOnError(err, "Failed to connect to RabbitMQ")
defer connection.Close()
//创建一个Channel
log.Printf("got Connection, getting Channel")
channel, err := connection.Channel()
failOnError(err, "Failed to open a channel")
defer channel.Close()
//创建一个exchange
log.Printf("got Channel, declaring Exchange (%q)", exchange)
err = channel.ExchangeDeclare(
exchange, // name of the exchange
exchangeType, // type
true, // durable
false, // delete when complete
false, // internal
false, // noWait
nil, // arguments
);
failOnError(err, "Exchange Declare:")
//创建一个queue
q, err := channel.QueueDeclare(
queueName, // name
false, // durable
false, // delete when unused
true, // exclusive 当Consumer关闭连接时，这个queue要被deleted
false, // no-wait
nil, // arguments
)
failOnError(err, "Failed to declare a queue")
//绑定到exchange
err = channel.QueueBind(
q.Name, // name of the queue
key, // bindingKey
exchange, // sourceExchange
false, // noWait
nil, // arguments
);
failOnError(err, "Failed to bind a queue")
log.Printf("Queue bound to Exchange, starting Consume")
//订阅消息
msgs, err := channel.Consume(
q.Name, // queue
"", // consumer
false, // auto-ack
false, // exclusive
false, // no-local
false, // no-wait
nil, // args
)
failOnError(err, "Failed to register a consumer")
//创建一个channel
forever := make(chan bool)
//调用gorountine
go func() {
for d := range msgs {
log.Printf(" [x] %s", d.Body)
}
}()
log.Printf(" [*] Waiting for messages. To exit press CTRL+C")
//没有写入数据，一直等待读，阻塞当前线程，目的是让线程不退出
<-forever
}
在AMQP客户端 ，当routing key为空的时候， 自动创建一个随机的queue，同时设置exclusive为true时，当这个Consumer关闭链接 时，会删除这个queue。
当使用fanout类型的exchange和没有名字的queue，Cusomer并不知道消息发送到了哪个queue,这个时候我们就需要用到QueueBind方法，来绑定到exchange。
过程中可以使用rabbitmqctl list_bindings命令来查看绑定的列表
查看结果
Console1(Consumer)，输出到文件:
lion@node1:~/_code/_rabbitmq/_golang$ go run consumer_exchange_logs.go &> consumer_exchange_logs.log
Console2(Consumer)，打印到控制台:
lion@node1:~/_code/_rabbitmq/_golang$ go run consumer_exchange_logs.go
使用Producer来发送消息:
lion@node1:~/_code/_rabbitmq/_golang$ go run producer_exchange_logs.go
2016/07/24 02:21:49 dialing "amqp://guest:guest@localhost:5672/"
2016/07/24 02:21:49 got Connection, getting Channel
2016/07/24 02:21:49 got Channel, declaring "fanout" Exchange ("test-idoall-exchange-logs")
2016/07/24 02:21:49 declared queue, publishing 16B body ("hello idoall.org")
2016/07/24 02:21:49 published 16B OK
这时可以使用rabbitmqctl list_bindings来查看我们的绑定信息，可以看到queueu的名字是随机的
lion@node1:~/_code/_rabbitmq/_golang$ rabbitmqctl list_bindings
Listing bindings ...
exchange amq.gen-D2AnzGsLUMhJCPk7YxgUUw queue amq.gen-D2AnzGsLUMhJCPk7YxgUUw []
exchange amq.gen-GC4VDS3mxsAOTEqii_WsWw queue amq.gen-GC4VDS3mxsAOTEqii_WsWw []
test-idoall-exchange-logs exchange amq.gen-D2AnzGsLUMhJCPk7YxgUUw queue []
test-idoall-exchange-logs exchange amq.gen-GC4VDS3mxsAOTEqii_WsWw queue []
使用cat命令，查看consumer_exchange_logs.log文件，可以看到内容被输入到文件中
lion@node1:~/_code/_rabbitmq/_golang$ cat consumer_exchange_logs.log
2016/07/24 02:25:17 dialing "amqp://guest:guest@localhost:5672/"
2016/07/24 02:25:17 got Connection, getting Channel
2016/07/24 02:25:17 got Channel, declaring Exchange ("test-idoall-exchange-logs")
2016/07/24 02:25:17 Queue bound to Exchange, starting Consume
2016/07/24 02:25:17 [*] Waiting for messages. To exit press CTRL+C
signal: interrupt
5.7、Direct exchange
RabbitMQ支持同一个binding key绑定到多个queue中。Direct exchange的算法就是通过binding key来做匹配的。
对于fanout的exchange来说，routing_key这个参数是被忽略的。
producer_exchange_direct_logs.go（消息生产者）:
package main
import (
"fmt"
"log"
"os"
"strings"
"github.com/streadway/amqp"
)
const (
//AMQP URI
uri = "amqp://guest:guest@localhost:5672/"
//Durable AMQP exchange name
exchangeName = "test-idoall-exchange-direct-logs"
//Exchange type - direct|fanout|topic|x-custom
exchangeType = "direct"
)
//如果存在错误，则输出
func failOnError(err error, msg string) {
if err != nil {
log.Fatalf("%s: %s", msg, err)
panic(fmt.Sprintf("%s: %s", msg, err))
}
}
func main(){
bodyMsg := bodyFrom(os.Args)
//调用发布消息函数
publish(uri, exchangeName, exchangeType, bodyMsg)
log.Printf("published %dB OK", len(bodyMsg))
}
func bodyFrom(args []string) string {
var s string
if (len(args) < 3) || os.Args[2] == "" {
s = "hello idoall.org"
} else {
s = strings.Join(args[2:], " ")
}
return s
}
func severityFrom(args []string) string {
var s string
if (len(args) < 2) || os.Args[1] == "" {
s = "info"
} else {
s = os.Args[1]
}
return s
}
//发布者的方法
//
//@amqpURI, amqp的地址
//@exchange, exchange的名称
//@exchangeType, exchangeType的类型direct|fanout|topic
//@body, 主体内容
func publish(amqpURI string, exchange string, exchangeType string, body string){
//建立连接
log.Printf("dialing %q", amqpURI)
connection, err := amqp.Dial(amqpURI)
failOnError(err, "Failed to connect to RabbitMQ")
defer connection.Close()
//创建一个Channel
log.Printf("got Connection, getting Channel")
channel, err := connection.Channel()
failOnError(err, "Failed to open a channel")
defer channel.Close()
//创建一个queue
log.Printf("got Channel, declaring %q Exchange (%q)", exchangeType, exchange)
err = channel.ExchangeDeclare(
exchange, // name
exchangeType, // type
true, // durable
false, // auto-deleted
false, // internal
false, // noWait
nil, // arguments
)
failOnError(err, "Failed to declare a queue")
// 发布消息
log.Printf("declared queue, publishing %dB body (%q)", len(body), body)
err = channel.Publish(
exchange, // exchange
severityFrom(os.Args), // routing key
false, // mandatory
false, // immediate
amqp.Publishing {
Headers: amqp.Table{},
ContentType: "text/plain",
ContentEncoding: "",
Body: []byte(body),
})
failOnError(err, "Failed to publish a message")
}
consumer_exchange_direct_logs.go（消息消费者）：
package main
import (
"fmt"
"log"
"os"
"github.com/streadway/amqp"
)
const (
//AMQP URI
uri = "amqp://guest:guest@localhost:5672/"
//Durable AMQP exchange name
exchangeName = "test-idoall-exchange-direct-logs"
//Exchange type - direct|fanout|topic|x-custom
exchangeType = "direct"
//AMQP binding key
bindingKey = ""
//Durable AMQP queue name
queueName = ""
)
//如果存在错误，则输出
func failOnError(err error, msg string) {
if err != nil {
log.Fatalf("%s: %s", msg, err)
panic(fmt.Sprintf("%s: %s", msg, err))
}
}
func main(){
//调用消息接收者
consumer(uri, exchangeName, exchangeType, queueName, bindingKey)
}
//接收者方法
//
//@amqpURI, amqp的地址
//@exchange, exchange的名称
//@exchangeType, exchangeType的类型direct|fanout|topic
//@queue, queue的名称
//@key , 绑定的key名称
func consumer(amqpURI string, exchange string, exchangeType string, queue string, key string){
//建立连接
log.Printf("dialing %q", amqpURI)
connection, err := amqp.Dial(amqpURI)
failOnError(err, "Failed to connect to RabbitMQ")
defer connection.Close()
//创建一个Channel
log.Printf("got Connection, getting Channel")
channel, err := connection.Channel()
failOnError(err, "Failed to open a channel")
defer channel.Close()
//创建一个exchange
log.Printf("got Channel, declaring Exchange (%q)", exchange)
err = channel.ExchangeDeclare(
exchange, // name of the exchange
exchangeType, // type
true, // durable
false, // delete when complete
false, // internal
false, // noWait
nil, // arguments
);
failOnError(err, "Exchange Declare:")
//创建一个queue
q, err := channel.QueueDeclare(
queueName, // name
false, // durable
false, // delete when unused
true, // exclusive 当Consumer关闭连接时，这个queue要被deleted
false, // no-wait
nil, // arguments
)
failOnError(err, "Failed to declare a queue")
if len(os.Args) < 2 {
log.Printf("Usage: %s [info] [warning] [error]", os.Args[0])
os.Exit(0)
}
for _, s := range os.Args[1:] {
log.Printf("Binding queue %s to exchange %s with routing key %s",
q.Name, exchange, s)
//绑定到exchange
err = channel.QueueBind(
q.Name, // name of the queue
s, // bindingKey
exchange, // sourceExchange
false, // noWait
nil, // arguments
);
failOnError(err, "Failed to bind a queue")
}
log.Printf("Queue bound to Exchange, starting Consume")
//订阅消息
msgs, err := channel.Consume(
q.Name, // queue
"", // consumer
false, // auto-ack
false, // exclusive
false, // no-local
false, // no-wait
nil, // args
)
failOnError(err, "Failed to register a consumer")
//创建一个channel
forever := make(chan bool)
//调用gorountine
go func() {
for d := range msgs {
log.Printf(" [x] %s", d.Body)
}
}()
log.Printf(" [*] Waiting for messages. To exit press CTRL+C")
//没有写入数据，一直等待读，阻塞当前线程，目的是让线程不退出
<-forever
}
查看结果
Console1(Consumer)，输出到文件:
lion@node1:~/_code/_rabbitmq/_golang$ go run consumer_exchange_direct_logs.go warning error &> consumer_exchange_direct_logs.log
Console2(Consumer)，打印到控制台:
lion@node1:~/_code/_rabbitmq/_golang$ go run consumer_exchange_direct_logs.go info warning error
2016/07/24 08:48:17 dialing "amqp://guest:guest@localhost:5672/"
2016/07/24 08:48:17 got Connection, getting Channel
2016/07/24 08:48:17 got Channel, declaring Exchange ("test-idoall-exchange-direct-logs")
2016/07/24 08:48:17 Binding queue amq.gen-vE-62-Lwt4VQYjlBbMLTjQ to exchange test-idoall-exchange-direct-logs with routing key info
2016/07/24 08:48:17 Binding queue amq.gen-vE-62-Lwt4VQYjlBbMLTjQ to exchange test-idoall-exchange-direct-logs with routing key warning
2016/07/24 08:48:17 Binding queue amq.gen-vE-62-Lwt4VQYjlBbMLTjQ to exchange test-idoall-exchange-direct-logs with routing key error
2016/07/24 08:48:17 Queue bound to Exchange, starting Consume
2016/07/24 08:48:17 [*] Waiting for messages. To exit press CTRL+C
使用Producer来发送消息:
lion@node1:~/_code/_rabbitmq/_golang$ go run producer_exchange_direct_logs.go error "Error. Error" && go run producer_exchange_direct_logs.go info "Info. Info" && go run producer_exchange_direct_logs.go warning "warning. warning"
我们可以看到，在Console2控制台上能够看到error、info、waring的所有消息，而在文件中只能看到和error相关的消息。
5.7、Topic exchange
对于Topic的exchange中Message的routing_key是有限制的，不能太随意。格式是以点号“."分割的字符表。比如："stock.usd.nyse", "nyse.vmw", "quick.orange.rabbit"。你可以放任意的key在routing_key中，不过长度不能超过255 bytes。
对于routing_key，有两个特殊字符（在正则表达式里叫元字符）
- * (星号) 代表任意 一个单词
- # (hash哈希) 0个或者多个单词
Topic exchange和其他exchange的区别,由于有"*"和"#"， Topic exchange 非常强大并且可以转化为其他的exchange:
- 如果binding_key 是 "#" - 它会接收所有的Message，不管routing_key是什么，就像是fanout exchange。
- 如果 "*"和"#"没有被使用，那么topic exchange就变成了direct exchange。
下面的代码中，我们将演示Topic的exchange使用"#"和"*"来匹配binding key。
producer_exchange_topic_logs.go（消息生产者）:
package main
import (
"fmt"
"log"
"os"
"strings"
"github.com/streadway/amqp"
)
const (
//AMQP URI
uri = "amqp://guest:guest@localhost:5672/"
//Durable AMQP exchange name
exchangeName = "test-idoall-exchange-direct-logs"
//Exchange type - direct|fanout|topic|x-custom
exchangeType = "fanout"
//AMQP routing key
routingKey = ""
//Durable AMQP queue name
queueName = "test-idoall-queues-direct"
)
//如果存在错误，则输出
func failOnError(err error, msg string) {
if err != nil {
log.Fatalf("%s: %s", msg, err)
panic(fmt.Sprintf("%s: %s", msg, err))
}
}
func main(){
bodyMsg := bodyFrom(os.Args)
//调用发布消息函数
publish(uri, exchangeName, exchangeType, routingKey, bodyMsg)
log.Printf("published %dB OK", len(bodyMsg))
}
func bodyFrom(args []string) string {
var s string
if (len(args) < 2) || os.Args[1] == "" {
s = "hello idoall.org"
} else {
s = strings.Join(args[1:], " ")
}
return s
}
//发布者的方法
//
//@amqpURI, amqp的地址
//@exchange, exchange的名称
//@exchangeType, exchangeType的类型direct|fanout|topic
//@routingKey, routingKey的名称
//@body, 主体内容
func publish(amqpURI string, exchange string, exchangeType string, routingKey string, body string){
//建立连接
log.Printf("dialing %q", amqpURI)
connection, err := amqp.Dial(amqpURI)
failOnError(err, "Failed to connect to RabbitMQ")
defer connection.Close()
//创建一个Channel
log.Printf("got Connection, getting Channel")
channel, err := connection.Channel()
failOnError(err, "Failed to open a channel")
defer channel.Close()
//创建一个queue
log.Printf("got Channel, declaring %q Exchange (%q)", exchangeType, exchange)
err = channel.ExchangeDeclare(
exchange, // name
exchangeType, // type
true, // durable
false, // auto-deleted
false, // internal
false, // noWait
nil, // arguments
)
failOnError(err, "Failed to declare a queue")
// 发布消息
log.Printf("declared queue, publishing %dB body (%q)", len(body), body)
err = channel.Publish(
exchange, // exchange
routingKey, // routing key
false, // mandatory
false, // immediate
amqp.Publishing {
Headers: amqp.Table{},
ContentType: "text/plain",
ContentEncoding: "",
Body: []byte(body),
})
failOnError(err, "Failed to publish a message")
}
consumer_exchange_topic_logs.go（消息消费者）：
package main
import (
"fmt"
"log"
"github.com/streadway/amqp"
)
const (
//AMQP URI
uri = "amqp://guest:guest@localhost:5672/"
//Durable AMQP exchange name
exchangeName = "test-idoall-exchange-topic-logs"
//Exchange type - direct|fanout|topic|x-custom
exchangeType = "topic"
//AMQP binding key
bindingKey = ""
//Durable AMQP queue name
queueName = ""
)
//如果存在错误，则输出
func failOnError(err error, msg string) {
if err != nil {
log.Fatalf("%s: %s", msg, err)
panic(fmt.Sprintf("%s: %s", msg, err))
}
}
func main(){
//调用消息接收者
consumer(uri, exchangeName, exchangeType, queueName, bindingKey)
}
//接收者方法
//
//@amqpURI, amqp的地址
//@exchange, exchange的名称
//@exchangeType, exchangeType的类型direct|fanout|topic
//@queue, queue的名称
//@key , 绑定的key名称
func consumer(amqpURI string, exchange string, exchangeType string, queue string, key string){
//建立连接
log.Printf("dialing %q", amqpURI)
connection, err := amqp.Dial(amqpURI)
failOnError(err, "Failed to connect to RabbitMQ")
defer connection.Close()
//创建一个Channel
log.Printf("got Connection, getting Channel")
channel, err := connection.Channel()
failOnError(err, "Failed to open a channel")
defer channel.Close()
//创建一个exchange
log.Printf("got Channel, declaring Exchange (%q)", exchange)
err = channel.ExchangeDeclare(
exchange, // name of the exchange
exchangeType, // type
true, // durable
false, // delete when complete
false, // internal
false, // noWait
nil, // arguments
);
failOnError(err, "Exchange Declare:")
//创建一个queue
q, err := channel.QueueDeclare(
queueName, // name
false, // durable
false, // delete when unused
true, // exclusive 当Consumer关闭连接时，这个queue要被deleted
false, // no-wait
nil, // arguments
)
failOnError(err, "Failed to declare a queue")
//绑定到exchange
err = channel.QueueBind(
q.Name, // name of the queue
key, // bindingKey
exchange, // sourceExchange
false, // noWait
nil, // arguments
);
failOnError(err, "Failed to bind a queue")
log.Printf("Queue bound to Exchange, starting Consume")
//订阅消息
msgs, err := channel.Consume(
q.Name, // queue
"", // consumer
false, // auto-ack
false, // exclusive
false, // no-local
false, // no-wait
nil, // args
)
failOnError(err, "Failed to register a consumer")
//创建一个channel
forever := make(chan bool)
//调用gorountine
go func() {
for d := range msgs {
log.Printf(" [x] %s", d.Body)
}
}()
log.Printf(" [*] Waiting for messages. To exit press CTRL+C")
//没有写入数据，一直等待读，阻塞当前线程，目的是让线程不退出
<-forever
}
查看结果
Console1(Consumer)，接收所有的日志:
lion@node1:~/_code/_rabbitmq/_golang$ go run consumer_exchange_topic_logs.go "#"
2016/07/24 09:28:29 dialing "amqp://guest:guest@localhost:5672/"
2016/07/24 09:28:29 got Connection, getting Channel
2016/07/24 09:28:29 got Channel, declaring Exchange ("test-idoall-exchange-topic-logs")
2016/07/24 09:28:29 Binding queue amq.gen-jW2-PIBg4izXpt96CynyFw to exchange test-idoall-exchange-topic-logs with routing key #
2016/07/24 09:28:29 Queue bound to Exchange, starting Consume
2016/07/24 09:28:29 [*] Waiting for messages. To exit press CTRL+C
Console2(Consumer)，接收以"kern"开头的日志:
lion@node1:~/_code/_rabbitmq/_golang$ go run consumer_exchange_topic_logs.go "kern.*"
2016/07/24 09:34:00 dialing "amqp://guest:guest@localhost:5672/"
2016/07/24 09:34:00 got Connection, getting Channel
2016/07/24 09:34:00 got Channel, declaring Exchange ("test-idoall-exchange-topic-logs")
2016/07/24 09:34:00 Binding queue amq.gen-8zYBz2uXYbWXcItJMZ3AQA to exchange test-idoall-exchange-topic-logs with routing key kern.*
2016/07/24 09:34:00 Queue bound to Exchange, starting Consume
2016/07/24 09:34:00 [*] Waiting for messages. To exit press CTRL+C
Console3(Consumer)，接收第二个单词以"critical"结尾的日志:
lion@node1:~/_code/_rabbitmq/_golang$ go run consumer_exchange_topic_logs.go "*.critical"
2016/07/24 09:37:21 dialing "amqp://guest:guest@localhost:5672/"
2016/07/24 09:37:21 got Connection, getting Channel
2016/07/24 09:37:21 got Channel, declaring Exchange ("test-idoall-exchange-topic-logs")
2016/07/24 09:37:21 Binding queue amq.gen-tq9QsD1i1mCps-jrqDtTTA to exchange test-idoall-exchange-topic-logs with routing key *.critical
2016/07/24 09:37:21 Queue bound to Exchange, starting Consume
2016/07/24 09:37:21 [*] Waiting for messages. To exit press CTRL+C
Console4(Consumer)， 可以创建多个绑定关系:
lion@node1:~/_code/_rabbitmq/_golang$ go run consumer_exchange_topic_logs.go "kern.critical" "A critical kernel error"
2016/07/24 09:39:35 dialing "amqp://guest:guest@localhost:5672/"
2016/07/24 09:39:35 got Connection, getting Channel
2016/07/24 09:39:35 got Channel, declaring Exchange ("test-idoall-exchange-topic-logs")
2016/07/24 09:39:35 Binding queue amq.gen-vcaHyCor5bbB2NX7YQhmzA to exchange test-idoall-exchange-topic-logs with routing key kern.critical
2016/07/24 09:39:35 Binding queue amq.gen-vcaHyCor5bbB2NX7YQhmzA to exchange test-idoall-exchange-topic-logs with routing key A critical kernel error
2016/07/24 09:39:35 Queue bound to Exchange, starting Consume
2016/07/24 09:39:35 [*] Waiting for messages. To exit press CTRL+C
使用Producer来发送消息:
lion@node1:~/_code/_rabbitmq/_golang$ go run producer_exchange_topic_logs.go "kern.critical" "A critical kernel error"
2016/07/24 09:56:33 dialing "amqp://guest:guest@localhost:5672/"
2016/07/24 09:56:33 got Connection, getting Channel
2016/07/24 09:56:33 got Channel, declaring "topic" Exchange ("test-idoall-exchange-topic-logs")
2016/07/24 09:56:33 declared queue, publishing 23B body ("A critical kernel error")
2016/07/24 09:56:33 [x] Sent A critical kernel error
2016/07/24 09:56:33 published 23B OK
5.7、远程调用RPC
之前的实例都是通过一个或多个Consumer来订阅消息，如果我们需要在远程机器上运行一个函数，来等待结果呢？这是一个不同的场景，例如做云计算。
AMQP协议预定义了14个属性，大多数我们都很少用到，以下几个是比较常用的。
- persistent：消息持久性
- content_type：用来描述编码的MIME类型
- reply_to：回调queue的名字
- correlation_id：将远程RPC请求，进行关联的唯一标识
correlation_id
如果为每个RPC的请求创建一个queue效率是非常低的，正常发送到queue的一个Message，它不知道是从哪里发过来的，而correlation_id属性的存在就是为每个请求设置一个唯一值，在回调接收消息的时候，也会带回这个属性进行匹配，如果不匹配，这个消息就不会被处理。
接下来我们将使用RabbitMQ搭建一个RPC系统：一个客户端和一个可扩展的RPC服务器，RPC的工作流程如下：
- 客户端启动时，创建一个匿名的exclusive callback queue
- 客户端发送请求时，要带两个属性reply_to（设置回调的queue）和correlation_id(唯一标识)
- 将请求发送到一个RPC queue
- RPC的server端 ，一直在等待请求，当消息到达时会对过reply_to回复到指定的queue
- 客户端在等queue从server的回调，检查 correlation_id是否一致，如果和请求时发送的一致，则做其他响应。
rpc_server.go（服务端代码）:
package main
import (
"fmt"
"log"
"strconv"
"github.com/streadway/amqp"
)
const (
//AMQP URI
uri = "amqp://guest:guest@localhost:5672/"
//Durable AMQP queue name
queueName = "rpc-queue"
)
//如果存在错误，则输出
func failOnError(err error, msg string) {
if err != nil {
log.Fatalf("%s: %s", msg, err)
panic(fmt.Sprintf("%s: %s", msg, err))
}
}
func main(){
//调用发布消息函数
publish(uri, queueName)
}
//发布者的方法
//
//@amqpURI, amqp的地址
//@queue, queue的名称
func publish(amqpURI string, queue string){
//建立连接
log.Printf("dialing %q", amqpURI)
connection, err := amqp.Dial(amqpURI)
failOnError(err, "Failed to connect to RabbitMQ")
defer connection.Close()
//创建一个Channel
log.Printf("got Connection, getting Channel")
channel, err := connection.Channel()
failOnError(err, "Failed to open a channel")
defer channel.Close()
//创建一个queue
log.Printf("got queue, declaring %q", queue)
q,err := channel.QueueDeclare(
queue, // name
false, // durable
false, // delete when usused
false, // exclusive
false, // no-wait
nil, // arguments
)
failOnError(err, "Failed to declare a queue")
//均衡处理，每次处理一条消息
err = channel.Qos(
1, // prefetch count
0, // prefetch size
false, // global
)
failOnError(err, "Failed to set QoS")
//订阅一个消息
//log.Printf("Queue bound to Exchange, starting Consume")
msgs, err := channel.Consume(
q.Name, // queue
"", // consumer
false, // auto-ack
false, // exclusive
false, // no-local
false, // no-wait
nil, // args
)
failOnError(err, "Failed to register a consumer")
forever := make(chan bool)
// 发布消息
go func() {
for d := range msgs {
n, err := strconv.Atoi(string(d.Body))
failOnError(err, "Failed to convert body to integer")
log.Printf(" [.] server端接收到的数据是 (%d)", n)
response := n*2
err = channel.Publish(
"", // exchange
d.ReplyTo, // routing key
false, // mandatory
false, // immediate
amqp.Publishing{
ContentType: "text/plain",
CorrelationId: d.CorrelationId,
Body: []byte(strconv.Itoa(response)),
})
failOnError(err, "Failed to publish a message")
d.Ack(false)
}
}()
log.Printf(" [*] Awaiting RPC requests")
//没有写入数据，一直等待读，阻塞当前线程，目的是让线程不退出
<-forever
}
consumer_exchange_topic_logs.go（消息消费者）：
package main
import (
"fmt"
"log"
"math/rand"
"os"
"strconv"
"strings"
"time"
"github.com/streadway/amqp"
)
const (
//AMQP URI
uri = "amqp://guest:guest@localhost:5672/"
//Durable AMQP exchange name
exchangeName = ""
//Exchange type - direct|fanout|topic|x-custom
queueName = "rpc-queue"
)
//如果存在错误，则输出
func failOnError(err error, msg string) {
if err != nil {
log.Fatalf("%s: %s", msg, err)
panic(fmt.Sprintf("%s: %s", msg, err))
}
}
func randomString(l int) string {
bytes := make([]byte, l)
for i := 0; i < l; i++ {
bytes[i] = byte(randInt(65, 90))
}
return string(bytes)
}
func randInt(min int, max int) int {
return min + rand.Intn(max-min)
}
func bodyFrom(args []string) int {
var s string
if (len(args) < 2) || os.Args[1] == "" {
s = "30"
} else {
s = strings.Join(args[1:], " ")
}
n, err := strconv.Atoi(s)
failOnError(err, "Failed to convert arg to integer")
return n
}
func main(){
rand.Seed(time.Now().UTC().UnixNano())
n := bodyFrom(os.Args)
log.Printf(" [x] 请求的数据是(%d)", n)
res, err := fibonacciRPC(n, uri, exchangeName, queueName)
failOnError(err, "Failed to handle RPC request")
log.Printf(" [.] 计算结果为 %d", res)
}
//RPC client调用方法
//
//@amqpURI, amqp的地址
//@exchange, exchange的名称
//@queue, queue的名称
func fibonacciRPC(n int, amqpURI string, exchange string, queue string) (res int, err error){
//建立连接
log.Printf("dialing %q", amqpURI)
connection, err := amqp.Dial(amqpURI)
failOnError(err, "Failed to connect to RabbitMQ")
defer connection.Close()
//创建一个Channel
log.Printf("got Connection, getting Channel")
channel, err := connection.Channel()
failOnError(err, "Failed to open a channel")
defer channel.Close()
//创建一个queue
log.Printf("got queue, declaring %q", queue)
q,err := channel.QueueDeclare(
"", // name
false, // durable
false, // delete when usused
true, // exclusive
false, // no-wait
nil, // arguments
)
failOnError(err, "Failed to declare a queue")
log.Printf("Queue bound to Exchange, starting Consume")
//订阅消息
msgs, err := channel.Consume(
q.Name, // queue
"", // consumer
true, // auto-ack
false, // exclusive
false, // no-local
false, // no-wait
nil, // args
)
failOnError(err, "Failed to register a consumer")
corrId := randomString(32)
err = channel.Publish(
"", // exchange
queue, // routing key
false, // mandatory
false, // immediate
amqp.Publishing{
ContentType: "text/plain",
CorrelationId: corrId,
ReplyTo: q.Name,
Body: []byte(strconv.Itoa(n)),
})
failOnError(err, "Failed to publish a message")
for d := range msgs {
if corrId == d.CorrelationId {
res, err = strconv.Atoi(string(d.Body))
failOnError(err, "Failed to convert body to integer")
break
}
}
return
}
查看结果
Console1(rpc server):
lion@node1:~/_code/_rabbitmq/_golang$ go run rpc_server.go
2016/07/24 11:20:32 dialing "amqp://guest:guest@localhost:5672/"
2016/07/24 11:20:32 got Connection, getting Channel
2016/07/24 11:20:32 got queue, declaring "rpc-queue"
2016/07/24 11:20:32 [*] Awaiting RPC requests
Console2(rpc client):
lion@node1:~/_code/_rabbitmq/_golang$ go run rpc_client.go 69
2016/07/24 11:24:37 [x] 请求的数据是(69)
2016/07/24 11:24:37 dialing "amqp://guest:guest@localhost:5672/"
2016/07/24 11:24:37 got Connection, getting Channel
2016/07/24 11:24:37 got queue, declaring "rpc-queue"
2016/07/24 11:24:37 Queue bound to Exchange, starting Consume
2016/07/24 11:24:37 [.] 计算结果为 138
以上只是简单实现了RPC的功能，如果你有复杂的需求，需要根据需求对Server和Client做调整。
6、写在后面
业界对于消息传输有很多种方案，之前我们也介绍过Kafka，Kafka是Linkedin于2010年12月份开源的消息发布订阅系统，它主要用于处理活跃的流式数据，大数据量的数据处理上。RabbitMQ在吞吐量方面稍逊于kafka，他们的出发点不一样，RabbitMQ支持对消息的可靠的传递，支持事务，不支持批量的操作。
RabbitMQ的消息应当尽可能的小，并且只用来处理实时且要高可靠性的消息。消费者和生产者的能力尽量对等，否则消息堆积会严重影响RabbitMQ的性能。
7、参考资料
http://www.rabbitmq.com/getstarted.html
https://github.com/streadway/amqp
8、FAQ
安装Erlang过程中出现提示configure: error: No curses library functions found
因为缺少缺少ncurses安装包，执行以下命令，即可解决：
lion@node1:~/$ sudo apt-get install libncurses5-dev
博文作者：迦壹 博客地址：[Ubuntu14.04+RabbitMQ3.6.3+Golang的最佳实践](http://idoall.org/blog/post/lion/14) 转载声明：可以转载, 但必须以超链接形式标明文章原始出处和作者信息及版权声明，谢谢合作！
