Setting the Connection URL

When a client connects to the WSO2 Message Broker, the connection parameters are specified using the connectionfactory interface as shown below.

connectionfactory.ConnectionFactory = <Connection_URL>
connectionfactory.QueueConnectionFactory = <Connection_URL>
connectionfactory.TopicConnectionFactory = <Connection_URL>

See the following topics for details

Parameters used in the connection URL

The connection URL takes the following format when the AMQP transport is used:

amqp://[<user>:<pass>@][<clientid>][/<virtualhost>][?<option>='<value>'[&<option>='<value>']]

For example:

connectionfactory.QueueConnectionFactory = amqp://admin:admin@clientID/carbon?brokerlist='tcp://IP1:5672'

Note that the clientID is used for identifying the client and is only applicable for durable topic subscriptions. However, since this value is not validated in the EI Message Broker, you can enter any arbitrary string as the clientID.

Now, let's look at the parameters used in the above URL format:

<user>:<pass>@: This is the username:password that will be used to connect to EI Message Broker. Note that this user should have the required permissions granted in the broker. See the section for user permissions in EI Message Broker for more information on how permissions are defined.
/<virtualhost>: The name of the virtual host, where the virtual host is a path that acts as a namespace. A name consists of any combination of the following: At least one alphanumerical value [A-Za-z0-9] and optionally special characters [.-_+!=:].

<option>='<value>': You can enter multiple options with values as explained below. These options should be separated by '&'.

Option Description

brokerlist

The list of brokers to use for this connection. The value should contain the URL of the broker as well as any other optional values. You can add any number of broker URLs separated by ';' as shown below.

brokerlist='<broker url>[;<broker url>]'

See the topic below on specifying the list of broker nodes for details on how to configure the broker URL.

failover This option controls how failover occurs when you have a list of brokers. The value used with the failover option should contain the failover method as well as any other optional values. See the topic below on Using the failover option for details.

redeliverydelay

This option can be used to specify the required delay in redelivering a message to the subscriber client when the first attempt fails. The value should be in milliseconds.

The list of brokers nodes

There may be one or several message broker nodes set up. Therefore, the client can use the 'brokerlist' option in the connection URL to specify the list of available broker nodes. The broker URL should be as follows:

<transport>://<host>[:<port>][?<option>='<value>'[&<option>='<value>']]

Now, let's look at each of the parameters used in the broker URL:

<transport>: The transport should be TCP.

To support more transports, the ''client.transportTransportConnection'' class needs to be updated along with the parsing to handle the transport.
<host>: The IP address.
<port>: The default AMQP port of 5672 is used if no port is specified.

<option>='<value>': Each broker can have additional options that are specific to that broker. The following are the options that are currently implemented:

Option	Default Value	Description
`retries`	1	The number of retry attempts when connecting to the broker.
`ssl`	false	Use SSL on the connection.
`connecttimeout`	30000	How long (in milliseconds) to wait for the connection to succeed.
`connectdelay`	none	How long (in milliseconds) to wait before attempting to reconnect. The recommended value is 30000 milliseconds.

Handling failover

When you use the failover option, the following format should be followed:

failover='<method>[?<options>]'

Now, let's look at the parameters in the above format:

<method>: Listed below are the supported methods. Note that 'singlebroker' is used when only one broker is present and the 'roundrobin' method is used with multiple brokers. The 'nofailover' method is useful if you are using a 3rd party tool that has its own reconnection strategy that you wish to use.

Method	Description
`singlebroker`	This will only use the first broker in the list.
`roundrobin`	This method tries each broker in turn.
`nofailover`	[New in 0.5] This method disables all retry and failover logic.
onetime	This method ensures that a connection of XA transactions does not failover. See Handling Distributed Transactions for more information

The <method> value in the URL may also be any valid class on the classpath that implements the FailoverMethod interface.

<option>: The following options should be used for the failover method.
Option Default Value Description
cyclecount
1
The number of times to loop through the list of available brokers before failure.

Example

For example, see how multiple brokers are defined in the connection URL, along with failover parameters.

connectionfactory.QueueConnectionFactory = amqp://admin:admin@clientID/carbon?failover='roundrobin'&cyclecount='2'&brokerlist='tcp://localhost:5673?retries='5'&connectdelay='50';tcp://localhost:5674?retries='5'&connectdelay='50';tcp://localhost:5675?retries='5'&connectdelay='30000''