I am still struggling with undertsanding some of Camel's main features and limitations.
My objective is to implement a demo application that can migrate camel endpoints. To achieve this everyone suggested that I should use the camel load-balancer pattern with the failover construct.
To achieve this objective people have suggested Fuse and ActiveMQ. Some have even suggested JBoss, but I am lost.
I understand that Camel needs the an implementation of a JMS server. To achieve this I can use ActiveMQ - a free implementation of a JMS server.
However camel also provies the jms-component. What is this? Is this a client implementation of JMS? If so, should I not be using an ActiveMQ client for JMS? Could someone provide a working example?
With ActiveMQ and JMS understood I can then try to find out why people suggest Fuse. I want my implementation to be as simple as possible. Why do I need Fuse? The Camel+ActiveMQ combination has the load balancer pattern with the failover mechanism right?
I am lost in this sea of new technologies, if someone could give a direction I would be thankful.
Camel provides two components. The first is the jms component, which is a generic API for working against JMS servers. The other is the activemq component, which uses the activemq API for working with activemq message brokers. The activemq component is the default component within things like servicemix/fuse, using an internal broker (not a networked/external broker).
If you are connecting to activemq, you can use either the activemq component or the jms component. The jms component will not start up a broker automatically, you would need to do this yourself.
Fusesource == JBoss Fuse == Apache ServiceMix + some addons. For argument sake, i'm going to refer to all three of these as ServiceMix.
ServiceMix is an enterprise service bus, you can lookup the term on wikipedia if you're not familiar with the concept. It uses Apache Camel to define routes between your components, implementing a number of integration patterns as you so need. ServiceMix deploys by default with Apache CXF, for JAX-RS and JAX-WS services and Apache ActiveMQ, a JMS message broker. Using Camel, you can tell service mix that when a REST API is called, do a series of steps, each step decoupled from the one before it.
JBoss Fuse (the enterprisey, costs money edition) comes with some additional components around fail over. Some of these are present in servicemix (namely, you can run servicemix in a hot stand by mode, waiting for the primary to go down). The Camel load balancer pattern doesn't really mean anything around replication, except that a message coming from one endpoint can be delivered to any of a set of a N endpoints. http://camel.apache.org/load-balancer.html
On the flipside, take a look at ServiceMix's failover http://servicemix.apache.org/docs/4.4.x/users-guide/failover.html
I think based on your question you're referring to system failure failover (needing to work against a new instance), and not a Camel Loadbalancer component (which is likely where the confusion is coming from, on the community side and your side).
start by reading these...Camel In Action, ActiveMQ In Action
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I have Apache Camel application deployed on two servers and they consume from JMS endpoint. I want to make sure that only one camel route is consuming from jms endpoint at a time. The only option that I can use for clustering is using database as a lock store. Does Apache Camel provide such a feature?
I think the easiest way is to consume from a topic and not a queue.
On connection, use the same subscriptionName. Only the first connection will be allowed as far i know.
We are in a plan of migration from 5.x to the newest version (i.e. ActiveMQ Artemis) and we need a couple of clarifications if any one has done or used Camel as client application.
We are currently connecting via Camel ActiveMQ component and I don't see any Artemis component as such in Camel. We do have other components such as JMS, SJMS, AMQP. Any thoughts on which one to go for and recommended for connecting to Artemis? I think I have options of using core, AMQP protocols in new version if want to go away with OpenWire. If core protocol is intended for applications migrating from JBoss, good to go with AMQP component which underneath uses AMQP protocol and conforms to JMS specifications?
There is no Camel component specifically for ActiveMQ Artemis like there is for ActiveMQ 5.x. However, ActiveMQ Artemis supports the OpenWire protocol which is what the ActiveMQ Camel component uses so your client applications don't necessarily need to change.
If you want to change your Camel applications then you can use the JMS or SJMS Camel components with any of the following JMS client implementations:
OpenWire JMS (shipped with ActiveMQ 5.x)
core JMS (shipped with ActiveMQ Artemis)
Qpid JMS (independent JMS client implementation using AMQP)
You can also use the AMQP Camel component with the Qpid JMS client if you like.
Which component you use is entirely dependent on your specific use-case. You haven't really provided any specifics about your use-case so it's impossible to provide guidance there. You'll need to evaluate the pros and cons of each approach and decide for yourself.
Could anybody explain how Apache Camel is able to behave as a routing and mediation engine on a JAXRS API?
As far I've being reading about I've not been able to figure out what's it for?
You can consider Apache Camel as a great integration framework. It doesn't provide functionality itself, but it makes easy to glue multiple services and protocols together.
Apache Camel can expose a REST endpoint using the CXFRS component. This means it listens for a REST call on certain endpoint (URL). On invocation it doesn't invoke the implementing bean (service) itself, but executes a defined mediation route (invoke a route with its Exchange object).
It is very useful when you need to integrate multiple services or translate the call to other protocols. You can implement a REST service by a bean itself and it's ok until the bean provides some functionality or data itself. For integration you often need more flexibility to integrate multiple sources and protocols. Then Apache Camel can be much more practical tool.
Can anyone give me a sample source code where i can use restful jax-rs web service as an interface to message broker using active mq. The requirement is traffic comes to application through jax-rs webservice and the message is transferred to active mq which is processed asynchronously and the consumer on active mq inserts data into db. Can anyone please provide sample code, that would be great
The question is very fuzzy. There are multiple concerns to take into account when doing this kind of interfaces as jax-rs is a http interface (synchronous, non transcational, non persistent, non guaranteed delivery) while activemq (jms) is the other way around, asynchronous, transactional and persistent.
I suggest you take a look at Apache Camel which is a lightweight integration framework that works really good with ActiveMQ. It supports JAX-RS as well. There are multiple code examples over at the Camel website and connecting rest with activemq is rather easy given you have your case fully designed.
Can Camel connect to Sonic ESB?
I could not find any camel-sonic integration specific example. That's why I am confused if it is possible at all.
Connecting ESBs in general does not require specific transports since ESBs are connectivity software packages. You could probably pick and choose which transport fits you best and get started.
I had a look at Sonic ESB as I have never worked with it. However I can see a couple of ways you can integrate camel routes with the ESB.
Web services: If you are hosting web services on the Sonice ESB camel is more than capable of calling these web services from a camel route.
JMS: If Sonic ESB can host a JMS route (I am sure it can but could be wrong) you can just send JMS messages from your Camel route to the JMS queues hosted by Sonic ESB.
The JBI Component: Some ESB's such as Apache ServiceMix and OpenESB is based on the JBI standard. IF Sonic ESB uses this standard you should be able to send JBI messages directly to the Sonic ESB system.
Hope this gives you some pointers to look at.