Using Camel and its rabbitMQ module, how would I define an endpoint URL to a durable topic subscription? What options need to be set? what are corresponding options for what in camel JMS would be clientId and durableSubscriptionName?
You can use the rabbit-mq component found here:
http://camel.apache.org/rabbitmq.html
The parameter exchangeType can be set to topic.
Very simple example:
from("rabbitmq://localhost/A?routingKey=B&exchangeType=topic")
I found by experimentation that the exchange name to be used is "amq.topic", the routing key would be what would be the topic name and the queue name would be something unique based on the client id and the durable subscription name I would have used in JMS.
Souciance added correctly that the exchange type needs to be topic and autoDelete must be false. but there is no appid property on the Camel RabbitMQ consumer properties.
Related
I use Apache Camel 2.20x.
A camel component can be developed with a uri scheme for example "sample-component". Now the Endpoint of this component can actually extend an existing Endpoint say SQL which has uri syntax as "sql:<select query">.
Now I am listening to camel Exchange event (ExchangeSentEvent) When I retrive the uri from the event I get "sql:<select query">. But what I want is to get "sample-component". How can we achieve that. In simple terms following is the ask
How can we get all Endpoint uri schemes for a camel component.
Thanks in advance
Gk
ComponentName+Endpoint . You can see all the uri that the component will take. All camel components are named this way.There may be exceptions. also if u use intellij idea apache camel plugin it show .
examples
HttpEndpoint
TimerEndpoint
SedaEndpoint
DirectEndpoint
You can also find the consumer and producer classes of these components as follows.
HtppProducer if support HttpConsumer ..
Actually I am playing with apache-camel 2.15.2, the REST DSL available since Camel 2.14 is not complicated. However I can't find in the official documentation how to retrieve a query parameter, basically I would like to target my REST service in this way:
http://myServer/myService/myMethod?myQueryParam=myValue
Is that possible, or is there any workaround ?
Thanks in advance.
Camel uses the REST/HTTP component of choice (restlet, jetty, servlet, netty-http, spark-rest, etc) which maps query parameters as Camel message headers.
So yes you can with the rest-dsl exposes a REST service where clients can call it with query parameters, which is then mapped to Camel message headers during routing.
How do you set the TTL for a message when using Java DSL?
I have something like this:
...
from ("timer:something?delay=3000&period=15000")
...
.to("{{some.property}}")
.end()
...
I want to set a time to live on the message being sent.
I ended up setting the JMSExpiration header field of the messages being created similar to the following
.setHeader("JMSExpiration", constant(System.currentTimeMillis() + 1000))
We are using Apache ActiveMQ 5.7.
I assume TTL means Time to Live.
In Camel this is component specific how they deal with this. Some components support this, and others do not.
You should check the documentation for the component you use, what it supports.
If you use JMS component then it has the timeToLive option as documented: http://camel.apache.org/jms
And mind about the problem with "client and server clock's can be out of sync". There is some details on the Camel JMS page. Some message brokers has ways to sync the clocks, such as Apache ActiveMQ with its timestamp plugin: http://activemq.apache.org/timestampplugin.html
Scenario : I'll try to put an analogy with the loan broker example from the EIP book
The customer sends a quote request
(The loan broker requests customer credit score from the credit bureau)
The loan broker sends quote requests to each bank.
The problem
In my case point 1 and 2 are in the same camel context (or osgi bundle)
Each bank has a separate bundle, exposing endpoints to the loan-broker-bundle through NMR
loan-broker-bundle doesn't know about the banks beforehand since we keep partnering with new banks every now and then
What I did
Created a registry class and a bankDescriptor interface in loan-broker-bundle
each bank bundle when started calls the registery to add its bankDescriptor (spring init) that tells the loan broker what endpoint to call to get a quote.
loan-broker-bundle main route uses recipientList (a processor sets target endpoints by asking the registery) to route quote requests
The question
Hoping my description was clear enough, you can see that this is a really simple implementation. What are its limits ? How can i turn this registery into an osgi service ?
I developed a solution like this based on SpringDM for a client. There's a full write up of how to do this at http://www.jakubkorab.net/2012/05/system-integrations-as-plugins-using-camel-and-servicemix.html with full source code available at https://github.com/FuseByExample/smx-application-plugins
Hope that helps.
In OSGi there is a great registry at your disposal: The OSGi service registry. So my proposal is to do this slightly differently. Define a service interface for the quote requests and store it in a api bundle. Then let each bank implement this interface and publish the implementation as an OSGi service.
The loan broker bundle can then list all OSGi services in the OSGi service registry and call each to get the quote. In blueprint there is a nice tag that you can use to inject the list into a bean property of List. Spring DM perhaps has something similar.
Camel currently does not have way to call all OSGi services of a type. We discussed a new osgi service compomnent that would be able to do this. So probably we will soon have a solution.
A registry is a list of items with pointers for where to find the items, like the index on a database table or the card catalog for a library.
Correct me if I am wrong, from this definition, what I'd expect from a camel application registry is where a client application can (depending on the client protocol) do a lookup and based on metadata, selects a particular service and uses it as defined.
I am wondering if Apache Camel has anything close to this. Most of the service registries articles/implementations I have seen seems to address only SOAP protocols.
Regards.
You can use the REST API from camel-web to lookup routes and endpoint which is the "services" in Camel.
http://camel.apache.org/web-console.html
In terms of a SOA service registry then you may look at other products which specialize in that such as Apache ZooKepper
http://hadoop.apache.org/zookeeper/
You can use ManagementStrategy SPI to hook into events in Camel and track services as they are created/started/stopped etc. Then you can bridge that to your SOA service registry product of choice.
you can also use the CamelContext getEndpoints() and getEndpointsMap() APIs to browse the endpoints
see this post for some general monitoring information...
http://benoday.blogspot.com/2011/01/apache-camel-monitoring.html