I'm trying to build MQTT support into my Spring application. For this I'm looking at the references provided by Spring, which can be found here here.
They provide sample code for inbound and outbound channel adapters, but this concept of adapters is unclear to me. I couldn't find a lot of information about it on the web.
What exactly are these adapters and why are they needed?
Where do I need to define these adapters and how do I access them?
I'm using eclipse as my IDE and maven as my buildtool.
The adapters are a concept from Spring Integration which is yet another Spring project that provides an implementation of the Enterprise Integration Patterns and provides an abstraction layer that standardizes the way you integrate with external system, whether they are based on JMS, FTP or as in your case MQTT.
As with so many other Spring projects, the driver behind it is a loose coupling and standardization that will enable you to swap your channel provider (e.g. if its a JMS provider swap RabbitMQ with ActiveMQ or vice-versa) with a minimal impact to the rest of you code.
Its comparable to Apache Camel, in case your more familiar with it, and this comparison is quite an interesting read
Related
Learning Spring Integration. I am trying to understand the IntegrationFlow DSL and the use of its to(IntegrationFlow) method.
It seems that this allows us to daisy-chain the end of Flow 1 with the beginning of Flow 2.
Is this the DSL's implementation of the Message Bridge pattern, where channels are connected to each other? If not, how is this different than a Message Bridge? Is it similar to the direct: and seda: endpoints in Apache Camel parlance, that is, a way of snapping routes together?
Yes, we can treat it that way, but technically it is just composition of more high-level messaging abstractions together. There is no EIP Message Bridge pattern implementation as a single top-level component.
Let's see it objective:
How can multiple messaging systems be connected so that messages available on one are also available on the others?
Use a Messaging Bridge, a connection between messaging systems, to replicate messages between systems.
So, let's say we need to transfer data from Apache Kafka topic into some IBM MQ queue. For Kafka we use an KafkaMessageDrivenChannelAdapter and for IBM MQ - JmsSendingMessageHandler. We connect them via DirectChannel the rest is done with internal (de)serializers to remap Kafka records into JMS messages. Does this approach implement the mentioned pattern? I think yes. And with different channel adapters we can implement many use-cases transferring data from one source to another.
And that Message Bridge confirms our assumption:
The Messaging Bridge is a set of Channel Adapters.
Now about to(IntegrationFlow) operator. This is just a convenient API to decompose your configuration between different logical, reusable pieces. At runtime we don't have any IntegrationFlows interacting: only endpoints are exchanging messages via channels between them.
Yes, you can treat Camel's direct: and seda: as a MessageChannel abstraction in terms of Spring Integration. Yes, we can say that this separation via channel is a bridge we have talked before. But in terms of Spring Integration sometimes there is no reason to separate the logic and people just do this:
IntegrationFlow.from(Kafka.messageDrivenChannelAdapter())
.handle(Jms.outboundAdapter())
.get();
Is this a bridge we saw before? I guess yes. Even if we don't have an explicit channel definition it is still there for us auto-created by the framework.
I manage a now fairly large Spring Integration application. Recently, we wanted to add a batch job using Spring Batch (rationale: administration, monitoring, scheduling, ability to restart in case of failure anywhere along the way).
Since we have developed a lot of connectors to the company services, we planned to reuse them in the batch, so I have been looking closely at how Spring Batch and Spring Integration work together (among other things: Spring Batch Integration). What we had in mind was to somehow implement Spring Batch tasklets using (already available) Spring Integration components.
I may have missed something fundamental at the Spring core level but I wasn't able to figure out a simple way to "invoke" a Spring Integration endpoint from a Spring Batch tasklet (if we forget complicated plumbing like RMI calls, "remote chunking", "remote partitioning"...)
Did I miss something ?
This is a very common use case (invoking an integration flow from a batch job/step).
Simply wire an integration gateway into the tasklet.
In recent applications, it's quite common to use the MessagingGateway annotation or the DSL. But, if you're more familiar with XML, then a <gateway/> will work well too.
Spring integration is used to make the communication between two systems easier.
So does that mean the if two systems are talking using JMS queus, then we can remove queues and integrate two systems using Spring Integration Framework?
Looks like you should study more on the matter. I mean EIP-book, Spring Integration in Action or, at least the Reference Manual from Spring IO site.
The main Spring Integration goal is integration and JMS is only one way to do that.
If your two system can get deal with JMS, there is no stops to integrate them using Spring Integration: just provide JMS adapters for boht of them.
As per my understanding,
Spring Integration solution a framework level solutions to Design Patterns listed in http://eaipatterns.com/
I might be an alternate to ESB which is like one big tunnel & everything passes through that.
Spring Integration provides end to end message between different de-coupled, disparate connecting points.
On the other hand JMS is an API in the Java EE spec which can be used in conjunction with Spring-Integration.
You might as well want to read about AMQP which is a messaging protocol.
I am new to the enterprise integration area.
We have a requirement to develop a solution where multiple OSS (operations support systems) should talk to multiple EMS (element management systems) and network devices (Different transports and protocols has to be supported), solution should be such that, that it should run in Weblogic.
Queries
Which will be the best fit for this situation ESB/Apache ServiceMix/Spring Integration?
If we use opensource ESBs ( like WSo2 and Talend ESBs) I think we need to maintain two servers ESB server and Weblogic server and ESB/Weblogic integration will be an issue?
Apache servicemix or Spring Integration be deployed/run inside Weblogic?
Whether Apache ServiceMix is supported now, as I could see most updates are happening in fuse ESB only?
You need to analyze your scenario and then decide. If you need only transformation or alongside with a simple routing you can use some frameworks like smooks, camel etc.
You need to transform and still a lot of system involved where you need those transformed messages then you could use an ESB.
Then comes selecting the ESB product is also based on you application eco system. All products are amazing and each fits the better than the other in their own application eco system.
First you need to know a few things on Camel / Fuse ESB / Service Mix
All the above revolve around the same, each of them are projects where camel integration framework is the coding De fact o
1.Camel -- Integration framework and the De fact o coding way(sophisticated in its own way and much flexible)
2.Service Mix -- Container for deploying the your integration code. (Camel integration code)
3.Fuse ESB -- Enterprise Feather on the hat of Service Mix where it provides a Studio for coding , a list of components and wrappers like clustering and other facilities around service service mix
.
I would like you to also consider Mule ESB which could also and it will be a good contender in your list.
Some answers for your questions
1.You can deploy Camel code or the spring integration code into the what so ever container (all in the hands Maven and jar management thing you need to do....)
2.Service mix is a Apache license and is complete open source and if you need some support I suggest you to choose the FUSE ESB which is not part of JBoss family and powered by RedHat
Please follow this link below for more detailed discussion from other stackoverflow.com users
use the below for your analysis
Apache Camel and other ESB products
What is an ESB and what is it good for?
Messaging, Queues and ESB's - I know where I want to be but not how to get there
JMS and ESB - how they are related?
we are building a distributed Java system (should be scalable ;-) ) that is connected only with JMS (ActiveMQ). I studied Spring Integration and I am not sure what the advantage would be if we use it. I think we are better off with using the JMS-Templeate from the Spring Core Project as we send only messages from a JavaService to another JavaService and so on.
Use Spring Integration (or any other framework) if you think the extra abstraction that it buys you is worth the cost. It should give you a more solid foundation on which to build your application. Software written by Spring is better than anything you or I would write from scratch.
All frameworks have a cost. There are additional dependencies. Sometimes greater abstraction can obscure too much.
You should prototype with and without Spring Integration to see if it's worth the cost.
If you're not a Spring user already, I'd recommend that you learn Spring before jumping into a big enterprise project.
SpringIntegration will give your Enterprise Integration Pattens ready to use.
Are you going to need splitters, routers, filters, gateways, aggregators, transformers, etc?
If the answer is no, go for plain Java+ActiveMQ.
If you need a really powerful system integration tier, then you should use Spring Integration - it's an additional level of abstraction which may help when your system will grow. With SI it's a matter of seconds to add new integration processing rule between two systems.
From the other hand, I've worked on some SpringIntegration+ActiveMQ project, and it was almost impossible to configure this broker to work with SI in the reliable way. So if you decide to use SI I'd recommend HornetQ as a JMS broker - this one works fine.