IBM Sterling B2B Integrator fails to start - United States
AMQ JMS is a Java Message Service (JMS) client for use in messaging This chapter guides you through the steps required to install AMQ JMS in your environment. . and check the console for any critical errors logged during startup. .. the connection will be failed if the peer sends no AMQP frames. Cleaning up Dead Connection Resources on the Server. Before an Apache Closing core sessions or JMS connections that you have failed to close. As previously init>(porkostournaments.info) at porkostournaments.infooject. YourClass. ActiveMQ fails to start on Dev and Prod instances. Invocation of init method failed; nested exception is porkostournaments.info ConnectException: Connection refused to host: devsrv7; nested Add values or modify them as necessary.
The latter condition is enough that the cursor for queue A cannot load any more messages into memory. The consumer for queue A gets starved as a result.
If there are other destinations with no messages loaded into memory, but there are messages in the store and active consumers connected, they get starved as well. How to Identify This Problem The following conditions should all be met when you run into this problem: Do you detect consumer s that receive no messages despite a queue backlog? Look at the brokers overall MemoryPercentUsage. How to Resolve This Situation On a running broker you can either connect a consumer or more to queue A and start consuming messages, or if you can afford it from a business perspective, purge the queue A.
Restarting the broker would also help, as after the restart messages only get loaded from the store if there are consumers connected. The many messages of queue A won't be loaded unless there is a consumer connected, and even then the cursor loads maxPageSize number of messages only in one go as you surely learned by now.
Starving JMS Consumers in ActiveMQ
Configuring destination limits would typically also work around the problem. However, no fix was made, as fixing turned out to be very difficult. Yes, as with that much background now, we can come to the second symptom of this problem.
Above I talked about one or more destinations with large backlog s and no consumers starving consumers of other destinations. If you think this further, perhaps queue A does have a consumer connected, but the consumer is much slower than the rate at which messages get produced. Perhaps it takes a few seconds to process each message not entirely off the world for certain use cases. Now imagine we have multiple destinations like queue A: Now think a second about what happens to other destinations that have fast consumers and almost no backlog.
These destinations could see a high throughput in general. It's the same problem as above.
In essence these fast consumers do not get starved completely, but they get slowed down pretty much to the speed of the slow consumers on other destinations. I produced a unit test that shows this problem in action. Again the solution to this problem is to set destination limits for at least the destinations that have slow consumers and a large message backlog. A registry does not have to be public or globally accessible.
IRI is an acronym for internationalized resource identifier. Components Component is confusing terminology; EndpointFactory would have been more appropriate because a Component is a factory for creating Endpoint instances. For example, if a Camel-based application uses several JMS queues then the application will create one instance of the JmsComponent class which implements the Component interfaceand then the application invokes the createEndpoint operation on this JmsComponent object several times.
Each invocation of JmsComponent.
Failed to connect to Broker. Caused by: User name [system] or password is invalid.
Actually, application-level code does not invoke Component. Instead, application-level code normally invokes CamelContext. Consider the following code.
The URI prefix that is, the part before ": Internally, the CamelContext object maintains a mapping from names of components to Component objects. For the URI given in the above example, the CamelContext object would probably map the pop3 prefix to an instance of the MailComponent class. Then the CamelContext object invokes createEndpoint "pop3: The createEndpoint operation splits the URI into its component parts and uses these parts to create and configure an Endpoint object.
In the previous paragraph, I mentioned that a CamelContext object maintains a mapping from component names to Component objects. This raises the question of how this map is populated with named Component objects. There are two ways of populating the map. The first way is for application-level code to invoke CamelContext.
The example below shows a single MailComponent object being registered in the map under 3 different names. This approach relies on developers following a convention when they write a class that implements the Component interface. I illustrate the convention by an example.
Failed to connect to Broker. Caused by: User name [system] or password is invalid.
Let's assume you write a class called com. FooComponent and you want Camel to automatically recognize this by the name "foo". This is shown below. FooComponent If you want Camel to also recognize the class by the name "bar" then you write another properties file in the same directory called "bar" that has the same contents.
Once you have written the properties file syou create a jar file that contains the com. Then, when application-level code invokes createEndpoint "foo As I said in Section 4. The out-of-the-box support consists of classes that implement the Component interface plus properties files that enable a CamelContext object to populate its map of named Component objects.
Earlier in this section I gave the following example of calling CamelContext. I said that because the online Camel documentation and the Camel source code both claim the parameter is a URI. In reality, the parameter is restricted to being a URL. This is because when Camel extracts the component name from the parameter, it looks for the first ": To understand why, recall from Section 4.
Now consider the following calls to getEndpoint. It would be more useful if the latter components were identified as "urn: Message and Exchange The Message interface provides an abstraction for a single message, such as a request, reply or exception message. There are concrete classes that implement the Message interface for each Camel-supported communications technology.
The public API of the Message interface provides get- and set-style methods to access the message id, body and individual header fields of a messge. The Exchange interface provides an abstraction for an exchange of messages, that is, a request message and its corresponding reply or exception message. In Camel terminology, the request, reply and exception messages are called in, out and fault messages. There are concrete classes that implement the Exchange interface for each Camel-supported communications technology.
The public API of the Exchange interface is quite limited. This is intentional, and it is expected that each class that implements this interface will provide its own technology-specific operations. Application-level programmers rarely access the Exchange interface or classes that implement it directly.
However, many classes in Camel are generic types that are instantiated on a class that implements Exchange. Because of this, the Exchange interface appears a lot in the generic signatures of classes and methods. Processor The Processor interface represents a class that processes a message. The signature of this interface is shown below. For example, an implementation of this method initially might call exchange. If an error occurs during processing then the method can call exchange.
An application-level developer might implement the Processor interface with a class that executes some business logic. However, there are many classes in the Camel library that implement the Processor interface in a way that provides support for a design pattern in the EIP book.
For example, ChoiceProcessor implements the message router pattern, that is, it uses a cascading if-then-else statement to route a message from an input queue to one of several output queues. Another example is the FilterProcessor class which discards messages that do not satisfy a stated predicate that is, condition. Routes, RouteBuilders and Java DSL A route is the step-by-step movement of a Message from an input queue, through arbitrary types of decision making such as filters and routers to a destination queue if any.
Camel provides two ways for an application developer to specify routes. One way is to specify route information in an XML file.
A discussion of that approach is outside the scope of this document. Introduction to Java DSL For many people, the term "domain-specific language" implies a compiler or interpreter that can process an input file containing keywords and syntax specific to a particular domain.
This is not the approach taken by Camel. You can see this in the example below. Comments afterwards explain some of the constructs used in the example. The body of configure invokes methods such as fromfilterchoicewhenisEqualTootherwise and to.
In this way, these operations incrementally build up a Route object with a RouteBuilder wrapper around it and add it to the CamelContext object associated with the RouteBuilder. In addition, many integrated development environments IDEs provide an auto-completion feature in their editors. However, there is another option that the Camel documentation neglects to consider: Currently, Camel does not provide such a DSL parser, and I do not know if it is on the "to do" list of the Camel maintainers.
Continue Learning about Camel Return to the main Getting Started page for additional introductory reference information. At a high level Camel consists of a CamelContext which contains a collection of Component instances. A Component is essentially a factory of Endpoint instances. You can then create a Producer or Consumer on an Endpoint to exchange messages with it.
The DSL makes heavy use of pluggable Languages to create an Expression or Predicate to make a truly powerful DSL which is extensible to the most suitable language depending on your needs.