Apache ActiveMQ ™ -- Discovery Transport Reference
Using ActiveMQ > Configuring Transports > ActiveMQ Connection URIs > Discovery Transport Reference
The Discovery Transport
The Discovery transport works just like the Failover transport, except that it uses a discovery agent to locate the list of uri to connect to. The Discovery transport is also used by the Fanout transport for discovering brokers to send a fanout message to.
Configuration Syntax
discovery:(discoveryAgentURI)?transportOptions
or
discovery:discoveryAgentURI
Note that to be able to use Discovery to find brokers, the brokers need to have the multicast discovery agent enabled on the broker.
To configure discovery in a Broker you should use the Xml Configuration. Here is an example of using discovery. Its basically something like the following (see the discoveryUri)
Transport Options
Option Name
Default Value
Description
reconnectDelay
10
How long to wait for discovery
initialReconnectDelay
10
How long to wait before the first reconnect attempt to a discovered url
maxReconnectDelay
30000
The maximum amount of time we ever wait between reconnect attempts
useExponentialBackOff
true
Should an exponential backoff be used btween reconnect attempts
backOffMultiplier
2
The exponent used in the exponential backoff attempts
maxReconnectAttempts
0
If not 0, then this is the maximum number of reconnect attempts before an error is sent back to the client
group
default
an identifier for the group to partition multi cast traffic among collaborating peers; the group forms part of the shared identity of a discovery datagram (since 5.2)
Example URI
discovery:(multicast://default)?initialReconnectDelay=100
Applying parameters to discovered transports
From 5.4, transport parameters in the URI will also be applied to discovered transports if they are prefixed with discovered.; For example, adding the discovered.connectionTimeout parameter to the URI will apply the parameter to every discovered TCP transport, even though this parameter is not a Discovery transport option.