Multicast Transport Reference

The Multicast transport allow sending messages to or receiving messages from groups of multicast sockets. It is implemented on top of UDP and is highly scalable since knowledge of the receivers is not required.

Namespace and Syntax

XML namespace:

xmlns:multicast="http://www.mulesoft.org/schema/mule/multicast"

Connector syntax:

<multicast:connector name="mcConnector" receiveBufferSize="1024" sendBufferSize="1024"
               timeout="0" keepSendSocketOpen="false" broadcast="false"
               timeToLive="127" loopback="true'/>

Endpoint syntax:
You can define your endpoints 2 different ways:

Prefixed endpoint:

<multicast:inbound-endpoint host="localhost" port="65433"/>

Non-prefixed URI:

<inbound-endpoint address="multicast://localhost:65433"/>

See the sections below for more information.

Considerations

IP Multicasting is a service provided by IP (the internet protocol layer), that allows one-to-many communication. The most common use of IP Multicasting is to send UDP datagrams to multiple sockets located on different systems. Mule supports this with the Multicast transport. Note that, except for the communication being many-to-one instead of one-to-one, the Multicast transport is very similar to the UDP transport and the same considerations should be observed.

As shown in the examples below, the Multicast transport has two purposes:

Send messages to a group of IP Multicasting sockets
Read messages sent to a group of IP Multicasting sockets

Features

The Multicasting module allows a Mule application both to send and receive IP Multicasting datagrams, and to declaratively customize the following features of IP Multicasting (with the standard name for each feature, where applicable):

The timeout for sending or receiving messages (SO_TIMEOUT).
Whether to allow sending broadcast messages (SO_BROADCAST).
Whether to close a socket after sending a message.
The maximum size of messages that can be received.
The time to live for the packets that are sent
Whether to loop packets back to the local socket

Multicast endpoints can be used in one of two ways:

To receive an IP Multicasting datagram, create an inbound Multicast endpoint.
To send an IP Multicasting datagram, create an outbound Multicast endpoint.

Usage

To use Multicast endpoints

Add the MULE Multicast namespace to your configuration:
- Define the multicast prefix using xmlns:multicast="http://www.mulesoft.org/schema/mule/multicast"
- Define the schema location with http://www.mulesoft.org/schema/mule/multicast http://www.mulesoft.org/schema/mule/multicast/3.4/mule-multicast.xsd
Define one or more connectors for Multicast endpoints.
- Create a Multicast connector:
  <multicast:connector name="multicastConnector"/>
Create Multicast endpoints.
- Datagrams are received on inbound endpoints. The bytes in the datagram become the message payload.
- Datagrams are sent to outbound endpoints. The bytes in the message payload become the datagram.
- Both kinds of endpoints are identified by a host name and a port. The host name, in this case, is one of the standard IP multicast addresses defined in the IANA. When a datagram is sent to a multicasting host/port combination, all sockets subscribed to that host/port receive the message.

Multicast endpoints are always one-way.

Example Configurations

Copy datagrams from one port to another in a flow

<multicast:connector name="connector"/> ❶

<flow name="copy">
    <multicast:inbound-endpoint host="224.0.0.0" port="4444" exchange-pattern="one-way"/> ❷
    <pass-through-router>
        <multicast:outbound-endpoint host="224.0.0.0" port="5555" exchange-pattern="one-way" /> ❸
    </pass-through-router>
</flow>

The connector ❶ uses all default properties. The inbound endpoint ❷ receives multicasting datagrams and copies them to the outbound endpoint ❸, which copies them to a different multicasting group.

Configuration Options

Multicast Connector attributes

Name	Description	Default
broadcast	Set this to true to allow sending to broadcast ports.	false
keepSendSocketOpen	Whether to keep the the socket open after sending a message.	false
loopback	Whether to loop messages back to the socket that sent them.	false
receiveBufferSize	The size of the largest (in bytes) datagram that can be received.	16 Kbytes
sendBufferSize	The size of the network send buffer.	16 Kbytes
timeout	The timeout used for both sending and receiving.	system default
timeToLive	How long the packet stays active. This is a number between 1 and 225.	System default

Name

Description

Default

broadcast

Set this to true to allow sending to broadcast ports.

false

keepSendSocketOpen

Whether to keep the the socket open after sending a message.

false

loopback

Whether to loop messages back to the socket that sent them.

false

receiveBufferSize

The size of the largest (in bytes) datagram that can be received.

16 Kbytes

sendBufferSize

The size of the network send buffer.

16 Kbytes

timeout

The timeout used for both sending and receiving.

system default

timeToLive

How long the packet stays active. This is a number between 1 and 225.

System default

Configuration Reference

Element Listing