Life With Technology: July 2016

Friday, July 22, 2016

Camel installing dependencies

[Note : Following content is related to a Apache-servicemix-7.0.0.M2 test setup]

When we are creating routing with Camel, we may need to install dependencies to Camel.
As an example if we have created a mail sending route and deploy it in a fresh camel installation, you may get a error like following:

2016-07-22 14:50:35,439 | ERROR | rint Extender: 2 | BlueprintContainerImpl           | 28 - org.apache.aries.blueprint.core - 1.6.1 | Unable to start blueprint container for bundle blueprint.jms/0.0.1.SNAPSHOT due to unresolved dependencies [(&(component=smtps)(objectClass=org.apache.camel.spi.ComponentResolver))]
java.util.concurrent.TimeoutException
    at org.apache.aries.blueprint.container.BlueprintContainerImpl$1.run(BlueprintContainerImpl.java:371)[28:org.apache.aries.blueprint.core:1.6.1]
    at org.apache.aries.blueprint.utils.threading.impl.DiscardableRunnable.run(DiscardableRunnable.java:48)[28:org.apache.aries.blueprint.core:1.6.1]
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)[:1.7.0_79]
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)[:1.7.0_79]
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:178)[:1.7.0_79]
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:292)[:1.7.0_79]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)[:1.7.0_79]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)[:1.7.0_79]
    at java.lang.Thread.run(Thread.java:745)[:1.7.0_79]

It is because we have not installed a feature called "mail" as a dependency for Camel. There are several dependencies available. We can display them by typing karaf@root>feature:install camel- and tab.

We can install those dependencies with following command.
karaf@root>feature:install camel-mail

Now issue should be resolved.

Wednesday, July 20, 2016

Activemq REST API adapter for external systems

Following content is tested only with Apache ActiveMQ 5.13.3

If we need to implement a communication between a ActiveMQ JMS server and any REST support external system that is implemented with a technology which has no JMS API support, ActiveMQ REST API comes as a solution. So, this REST API can be introduced as an adapter for any External system to be connected with a ActiveMQ JMS server.

ActiveMQ REST API provides following services.
1. Publish a message.
2. Consume a message.
3. Get list of queues.
4. Get list of messages in a particular queue or topic.
5. Get the content of a particular message.

Publish a message

Method : POST
URI format :
http://localhost:8161/api/message/queue_or_topic_name?type=either_queue_or_topic&requestTimeout=time_in_miliseconds&body=message to send&clientId=any_unique_id_for_client
Example URI:
http://localhost:8161/api/message/FOO?type=queue&requestTimeout=1000&body=This is test 34&clientId=soapui

Consume a message

Method :GET
URI format :
http://localhost:8161/api/message/queue_or_topic_name?type=either_queue_or_topic&clientId=any_unique_id_for_client&requestTimeout=time_in_miliseconds
Example URI:
http://localhost:8161/api/message/FOO?type=queue&clientId=soapui&requestTimeout=1000

Get list of queues or topics

Method :GET
URI format :
http://localhost:8161/admin/xml/queues.jsp

Get list of messages in a particular queue or topic

Method :GET
URI format :
http://localhost:8161/admin/queueBrowse/queue_or_topic_name
Example URI:
http://localhost:8161/admin/queueBrowse/FOO

Get the content of a particular message

Method :GET
URI format :
http://localhost:8161/admin/queueBrowse/queue_or_topic_name?msgId=ID_value_of_a_particular_message_in_mentioned_queue_or_topic
Example URI:
http://localhost:8161/admin/queueBrowse/FOO?msgId=ID:dhcppc1-54766-1469009393902-5:1:1:1:4

NOTE:

If the authentication is enabled in the ActiveMQ admin as example in jetty.xml

<bean id="securityConstraint" class="org.eclipse.jetty.util.security.Constraint">
        <property name="name" value="BASIC" />
        <property name="roles" value="user,admin" />
        
        <property name="authenticate" value="true" />
    </bean>

we have to set security headers. If not 401 response will be received. So, following header should be set in the REST request

Authorization: Basic YWRtaW46YWRtaW4=

YWRtaW46YWRtaW4= equivalent to the base 64 encoded version of the provided_username:provided_password
(Username and password is one of set which you use to access to the ActiveMq webconsole.)