Chapter 3. Accepting Incoming Connections

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Network connections define how clients connect to your broker instance. In AMQ 7, these connections function differently and are configured differently than in AMQ 6.

3.1. Incoming Network Connections Changes

AMQ 6 and AMQ Broker 7 both enable you to define the way that clients connect to the broker. These connection points were called transport connectors in AMQ 6, but now are called acceptors in AMQ Broker 7.

AMQ 6 provided multiple implementations of the transport layer (such as TCP and NIO), which meant that you had to use different transport connectors depending on whether you wanted a client connection point to use a blocking or non-blocking transport. In AMQ Broker 7, the transport layer uses Netty only, which is non-blocking by default. There are two types of acceptors in AMQ Broker 7:


Netty TCP connections are used when the client and broker are located in different virtual machines, whether on the same server or physically remote.

Netty uses non-blocking (Java NIO) by default, which means that all client connections to the broker instance are non-blocking. It also has built-in support for WebSockets.

An In-VM connection is used when the client, whether an application or a server, resides within the same virtual machine as the broker.

AMQ 6 also required you to use separate transport connectors for each messaging protocol. In AMQ Broker 7, the low-level transport (either TCP or In-VM) is distinct from the messaging protocol used by the client (such as AMQP, MQTT, and so on). This means that a single acceptor can use multiple protocols on the same port. In fact, an acceptor will accept all supported message protocols unless you explicitly restrict the protocols that it can use.

For example, the default acceptor in AMQ Broker 7 automatically accepts all message protocols:

<acceptor name="artemis">tcp://;tcpReceiveBufferSize=1048576;protocols=CORE,AMQP,STOMP,HORNETQ,MQTT,OPENWIRE;useEpoll=true;amqpCredits=1000;amqpLowCredits=300</acceptor>

3.2. How Acceptors Are Configured

You use the BROKER_INSTANCE_DIR/etc/broker.xml configuration file to configure acceptors to accept incoming client connections for your broker instance.

The broker.xml configuration file contains the following default acceptors in the <acceptors> section:

       <!-- Acceptor for every supported protocol -->
       <acceptor name="artemis">tcp://;tcpReceiveBufferSize=1048576;protocols=CORE,AMQP,STOMP,HORNETQ,MQTT,OPENWIRE;useEpoll=true;amqpCredits=1000;amqpLowCredits=300</acceptor> 1

       <!-- AMQP Acceptor.  Listens on default AMQP port for AMQP traffic.-->
       <acceptor name="amqp">tcp://;tcpReceiveBufferSize=1048576;protocols=AMQP;useEpoll=true;amqpCredits=1000;amqpMinCredits=300</acceptor>

       <!-- STOMP Acceptor. -->
       <acceptor name="stomp">tcp://;tcpReceiveBufferSize=1048576;protocols=STOMP;useEpoll=true</acceptor>

       <!-- HornetQ Compatibility Acceptor.  Enables HornetQ Core and STOMP for legacy HornetQ clients. -->
       <acceptor name="hornetq">tcp://,STOMP;useEpoll=true</acceptor>

       <!-- MQTT Acceptor -->
       <acceptor name="mqtt">tcp://;tcpReceiveBufferSize=1048576;protocols=MQTT;useEpoll=true</acceptor>
The default acceptor, which accepts incoming client connections for any of the supported messaging protocols.

To configure the incoming client connections for your broker instance, you can modify the configuration properties for any of the default acceptors, or you can add new acceptors. This example shows a new acceptor configured to accept TCP connections using the OpenWire protocol:

<acceptor name="my_acceptor">tcp://;tcpReceiveBufferSize=1048576;protocols=OPENWIRE;useEpoll=true</acceptor>

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