IBM Liberty message consumption with fail-over - websphere

We are designing a solution that will consume messages from IBM MQ using JMS. The plan is to use WAS Liberty, so JMS is the technology of choice. We will create Message-Drive beans that will listen for messages in MQ queues.
We are considering both WAS Liberty and OpenLiberty as well.
The trick here is that we must implement it with fail-over, so that if one of our server fail, the other will keep consuming messages from MQ automatically. Like in a ative/passive mechanism.
I'm aware that the MQ adapter needs to be installed as it is not provided out-of-the-box.
I have the following questions:
Does WAS Liberty messaging implementation supports fail-over? Meaning that if the ative message consumer node fails, the stand-by node will automatically migrate and start consuming messages from MQ? What about OpenLiberty?
How can I configure the message system to work that way? Can you point out to the documentation?
Or is this feature only provided by WebSphere?

There is no such functionality in WebSphere Liberty or Open Liberty yet. You can create RFE here https://www.ibm.com/developerworks/rfe/?PROD_ID=544 .
There are ways to do it manually, check these links:
JMS Activation spec on Liberty: “WAS_EndpointInitialState” full profile equivalent property?
Controlling the state of endpoints at runtime
Solution that you could do:
create a script/application that will monitor your servers and call that API to enable/disable endpoint in specific server
or use Dynamic cluster/ auto scaling feature of Liberty and divide you app to two clusters - one with MDBs, one without. And then define policy that MDBs cluster has 1 instance always available. So once the server dies it is automatically restarted somewhere in the cluster
or use Kubernetes/ICP platform in the same way - so deploying 2 versions of app, and defining different replicasets parameters.

Related

JMS without any Third Party Messaging

I have few basic douts.
I have developed a JMS application for P-P and the messages are geeting stored in Jboss 7.1 JMS engine. My questions are below.
1.For any JMS application do we need to have any messaging engine like IBM MQ,HornetQ,Active MQ etc
If Yes then we need to configure the MQ to atlk to Appserver Messaging engine.
3.If No, Then we need to have to create a message consumer
JMS is a specification of a messaging interface - and a state model for how messages are handled in transactions.
jms.jar contains pretty much all interfaces - no implementations. Therefore whilst you can write an application against jms.jar you can't actually run it.
You'll need to pick some type of messaging provider. That's appropriate to your requirements.
That's not a discussion for here however keep in mind that they each have possible extensions and functional behavior outside of the specification so if you want to be portable between providers pay close attention to only use specification defined functionality.
Within a JavaEE Application Server there will be a JMS implementation that provides messaging features. Therefore an app here in JBOSS will be a MOM (messaging oridentated middleware) application. If you want the message to be accessed by an application not running in a JavaEE server then that is possible with some providers. There's often a JavaEE client container. Or the messaging engine will have a JavaSE based client that can be used. (WAS thin client client for example).
Remember that with JavaEE servers you are not restricted to a the choice of messaging provider - you can use the JCA interface to directly plug in a external messagin implementation. This might present an easier route if a lot of messaging will be outside the JavaEE server.
EDIT - added JavaEE notes

JMS without a queue

I am not expert in JMS and recently came across a situation in my project where they wanted to use JMS to communicate between applications. Is it possible to make use of JMS without an underlying MQ software like Websphere MQ / TIBCO EMS to communicate asynchronously. My thinking is that just like we use JDBC API to speak to a physical Database product (like Oracle/DB2 DB) underneath, we would use JMS to speak to a physical queue. But my team says just JMS and no queue. Can anyone help me understand? We use Websphere 6.0 server and use spring framework.
Thanks in advance.
You are correct: JMS is solely an interface, it contains no implementation. The comparison with JDBC is quite fitting.
When using JMS you always need a JMS provider. A provider is the JMS implementation, which interfaces a message oriented middleware.
Most application servers have built in JMS providers, so maybe your team meant using JMS without an external provider.
Is it possible to make use of JMS without an underlying MQ software like Websphere MQ / TIBCO EMS to communicate asynchronously
This makes no sense. Few points to note -
JMS is just specs. By specs you can imagine it as set of APIs/interfaces/ method signatures and governing rules.
There are various organization/companies that provide implementation of these APIs.Apache's ActiveMQ,IBM's Websphere MQ or TIBCO EMS are some of the examples.
Now when you say I want to use JMS then you need a JMS compatible server i.e server which understands the rules laid down by specs. This is generally know as MQ server and is provided by the provider.
My thinking is that just like we use JDBC API to speak to a physical Database product (like Oracle/DB2 DB) underneath, we would use JMS to speak to a physical queue. But my team says just JMS and no queue
Two things to note here. When you say you want to use databases and JDBC APIs to communicate JMS comes no where in the picture. Please understand why JMS is used. In short it is used to transfer messages between two decoupled system. What storage type JMS server uses(and if it is configurable) will depend on the provider. Generally all have DB storage type and can be configured to use your DB.
Next JMS has two types of communications - PTP(peer to peer) which uses queues and PUBSUB(publish subscribe) which uses Topics. When you say you are using JMS everything boils down to either of these two and some of it's variants.Now when you say JMS without a queue perhaps your team meant using PUBSUB. But again it is not something you decide randomly and use it in your application. This decision is takes as per what your requirement is as both of them behave differently.
First you will need queues/topics to use JMS.
Second (your team probably means not using WebSphere MQ because my team was saying the same thing)
This diagram in IBM's Red Book will fully answer your question (it is the same as WS6):
http://www.redbooks.ibm.com/redbooks/pdfs/sg247770.pdf
page 4.
Probably what you will be using is the WebSphere Default Messaging Provider.

Configuring JBoss EPA 6.1 with IBM MQ

I am developing a service for JMS messaging using IBM WMQ version 7.5 as Message oriented middleware. I am in a dilemma. The IBM specification says to use WebSphere MQ JMS API in JAVA EE environment. My sender and receivers will be in remote JBoss deployments. IBM provides a resource adapter to connect via JCA. This connection requires static administration of components such as Queue managers, queue channels, queue names.
Is JCA the best I can do ? Is there any other way where I can dynamically create the queues provided that I know other configuration details ? There will be multiple applications using this setup running on their own servers. If I use JCA, all have to make their own configurations. Can I make dynamic configurations ?
Typically within the application server environment resources would be created in some JNDI context. These would be Connection Factories and Destinations.
Depending on the app server, it may be possible to share this configuration across a network of individual servers. So typically there would be some set of static definitions.
However within say a servlet the MQConnectionFactory can be dynamically created.
In all cases the backing WMQ Resources do need to exist; though it is possible to send administrative command messages to WMQ to create queues and do other admin. The only exception is topics, accessing a topic string brings it into existence. Though this has default security properties that you might not want.

Not able to create jms queues in websphere programatically using standalone java client

I wrote a java client to connect to jms in websphere.
I was able to connect and produce and consume message.
Problem I am facing is when I do Session.createQueue(), websphere jms is not creating a new queue.
Please could some one throw some light on this issue...
Thanks in advance...
If you are working with WebSphere MQ as the messaging provider within WebSphere Application Server the queue will need to be created on the WebSphere MQ QueueManager first. This can be done either via the graphical WMQ Explorer or via the command line using the 'runmqsc' tool.
Information can be found for these via the WMQ InfoCentre - suggest doing a websearch for "WMQ Library" to get the latest link, currently though it is http://www-01.ibm.com/software/integration/wmq/library/index.html
Topics though don't need to be pre-created - though they can be if required. Various properties can be set different to the default.
If the Queue doesn't need to be permanent, for example as a temporary reply to then look into creating a temporary queue from the JMS Connection.
createQueue doesn't create a new queue. It simply creates a javax.jms.Queue object from a vendor specific identifier. javax.jms.Queue objects are just references to existing queues. Typically, you retrieve javax.jms.Queue objects from JNDI; createQueue is only useful in scenarios where using JNDI is not possible or not desirable.
Note: there is one exception to this, namely JMS providers that support autocreation of queues (I think ActiveMQ has such a feature).

How to create physical queue in JMS at run time

Want to know how to create physical queue in JMS at run time.
when I search for this I got Creating JMS Queues at runtime
But when I read http://activemq.apache.org/how-do-i-create-new-destinations.html I come to know queue which mention in Creating JMS Queues at runtime is not creating any physical queue at server side.
Please correct me if I m wrong. If any one know to create physical queue at run time please replay.
Thanks in advance.
The creation of "normal" queues is not adressed by the JMS standard. Depending on what you want to do there are two approaches:
use temporary queues -> however they have many restrictions, most commonly they are used forrequest-reply scenarios
use the API of the JMS provider - however your solution will be depending on this specific provider then
The JMS standard only addresses sending and receiving data from objects like queues and topics. Creation of JMS artefacts is vendor specific and most often requires using:
1)specific vendor APIs (not JMS)
2)command/admin messages aimed at the JMS server (command agents on activemq)
3)JMX API
I have used JMX method, which is the most powerful, but also the most work.
JMX Method for activemq (version 5.0+)
a) JMS Server Setup
1) Enable JMX in activemq startup scripts and activemq.xml files
2) If you are authenticating to to the server, make sure your user has admin privileges setup in activemq.xml (see http://activemq.apache.org/security.html)
3)restart activemq server
b) Your Client Code
1) create an instance of org.apache.activemq.broker.jmx.BrokerViewMBean (you will need to connect with some JMX connectivity code which is a bit messy)
2) use its addQueue method. This will create a queue on the server
(The process is similar for hornetq but since you mentioned Activemq I have omitted hornetq details here.)
I have used this method myself and it works.
An alternative is to use Command Agents in Activemq, but I have no personal experience with these. These are special messages contain admin commands and may do what you want as well.

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