We have a spring boot application that is growing in complexity because of integration needs - like send an email after you do this, or broadcast a jms message after you that etc. In looking for some higher level abstractions, I came across apache camel (haven't used camel ever before). The question that I have is what do I do with the spring boot application? The application has the standard spring controllers, services and uses spring-data for connecting to databases. I didn't find much help online on how to merge camel into a spring-boot restful application. Is that even something that is doable or is camel a completely different beast that the spring boot won't fit?
I did read that Camel tightly integrates with Spring, but still I didn't know if 1) Spring Controllers are still something that can be used along with Camel 2) If I can call the other spring beans from camel routes and whether I can call invoke a camel route from a spring bean (sorry if these sound like camel newbie questions to the experts)
As an example of what we have to do:
After finishing writing anything to the database about an order, we have to send an email out to the order processing department
If someone deletes a particular user address, we have to send to a jms topic so other applications can take action.
Every http request is coming in through the Spring MVC stack today.
Is there a way to "hand-off" the processing to camel after a particular task is complete? (like writing the order to the database successfully via the Spring MVC stack and hand off to camel to send a jms message and do other things)? Or should we completely replace Spring with Camel?
Not sure what the right path is. Can someone please guide us?
This question is slightly old, but though it was worth mentioning here that Apache Camel now includes a Spring Boot component.
Details can be found here
http://camel.apache.org/spring-boot.html
and they document an example here
http://camel.apache.org/spring-boot-example.html
Follow this for the current best practice in camelising a spring boot application!
One option is to
1> define camel routes either in Spring DSL or Java DSL or other means and define it in Spring Application context.
2> And have a class that implements ApplicationContextAware and cache the Spring ApplicationContext in a Static Variable.
3> For #Controller we can get this static variable and get hold of ApplicationContext .
4> With the camel context ID we can do a getBean from ApplicationContext.
5> This is the instance of DefaultCamelContext,with this we can do a createProducer and call camel routes from #Controller.
Like some others mentioned, spring-boot-camel (but use spring-boot-camel-starter as your dependency) works very well and it is really easy to set up. When you annotate your RouteBuilder extensions and your Processor implementations with #Component, they wire up directly into the context and you are good to go. Then, you can #Autowire a CamelContext or a ProducerTemplate into your classes and use them as necessary.
You asked about how Controllers can work with Camel, and if you #Autowire any of the things you need (probably a context or a producer template), then the answer is a definite "yes" that you can use them together quite easily. And when you use spring-web, your context will start and remain running without any additional configuration, etc.
Like Matthew Wells suggested, the links will get you pointed in the right direction. If you, or others on your team, are at all familiar with Camel, then it will be very easy for you to do what you need to do. But, ah, I notice that this question is from 2014, and you're probably well past the point of your question. At least if anyone else stops by this thread, they will have plenty of information to get going. If you come by and re-visit your question, please let us know how it went for you, and what you ended up doing. Cheers!
Related
Suppose I have some third party library and I want to integrate it with Spring in order to be able to use it as a part of Spring transaction. I didn't find any relevant information on the Internet and looked into the source code of integrations of RabbitMQ and MyBatis libraries. As I understood from their source code I should implement org.springframework.transaction.PlatformTransactionManager and interact with TransactionSynchronizationManager. And there are two questions:
How Spring "know" about and instanciate implementations of PlatformTransactionManager?
Suppose there are two resources been used in transaction through RabbitTemplate and
JdbcTemplate. What will be first committed - changes in database or
messages sent?
Also, I would be really appreciate if somebody point me out to some guide or book about interactions with Spring internals.
You have to instantiate them yourself, like a DataSourceTransactionManager or a HibernateTransactionManager. Spring Boot does that for you under the hood, but with plain Spring you need to do it yourself.
What you want are distributed transactions (XADataSource), which are not possible with RabbitMQ.
For RabbitMQ you should read this here first: https://www.rabbitmq.com/confirms.html . Then make sure you understand transactions on the JDBC side. Then you can reason about how they both work together.
For the Java side, you might enjoy this book entirely about transactions: https://www.marcobehler.com/books/1-java-database-connections-transactions
I have a web application with controllers, services and simple beans.
I want to use Spring Integration as a glue to link the beans. So instead of using a reference to the next bean to be called in a bean I just want to send (return) a message (e.g. a domain object) which would be the incoming parameter in the method signature of the next bean.
Is it a good idea to use Spring Integration for this? Would SI degrade the performance?
Thanks,
V.
Please, read the Reference Manual (http://projects.spring.io/spring-integration/) and other resources before asking similar questions. Spring Integration isn't a glue.
It's an Enterprise Integration Patterns implementation Framework. Even if it can do what you are asking, its purpose is much farther.
I'd say such a requirements may be addressed just with the raw ApplicationEvent model.
I have too many emails. I should write scheduler in order to send messages to them. Messages are different. I use spring framework 4.x.
I can write simple class, which connects to SMTP server. But in this case I should write my thread library too in order to send emails parallel.
Do spring have already written library which give me more flexible way to do this tasks? I do not want to use threads. It will be nice if spring already have this functionality.
Do I need Spring integration for this?
Best regards,
Yes, you definitely can do that with Spring Integration, because there is an ExecutorChannel implementation with can be supplied with an TaskExecutor from the Spring Core:
<channel id="sendEmailChannel">
<dispatcher task-executor="threadPoolTaskExecutor"/>
</channel>
<int-mail:outbound-channel-adapter channel="sendEmailChannel" mail-sender="mailSender"/>
But anyway you should keep in mind that all Spring Integration components are based on the Java and that ExecutorService is used on the background.
From other side if you need only the mail sending stuff from the Spring Integration, it would be an overhead and can simply use Core Spring Framework legacy like JavaMailSender as a bean and #Async for the sendMail method to achieve your parallel requirement.
UPDATE
could you tell me whether I need JMS for this situation?
I don't see any JMS-related stuff here. You don't have (or at least don't show) any real integration points in your solution. The same I can say even about Spring Integration just for email sending. However with the Spring Boot your SI config will be enough short. From other side if you'll study Spring Integration better eventually you'll get more gain to rely on the Integration components for your systems, as internally, as well as externally with other systems through JMS, AMQP, Kafka etc.
To be honest: a lot of years ago my first acquaintance with Spring Integration was due the requirement to get files from the FTP and have ability to pick up new files automatically. I found the solution only in the Spring Integration 1.0.0.M1. After that short XML config for the <int-ftp:inbound-channel-adapter> I loved Spring Integration and since that time it became as a part of my life. :-)
So, it's up to you to go ahead with Spring Integration in your simple app, or just follow with more formal solution with JavaMailSender direct usage.
You should use java executors framework. For example you can write something like the code below:
ExecutorService executor = Executors.newWorkStealingPool();
executor.execute(() -> mailSender.send(mail));
I am starting to learn the Spring Framework. I came across this link but I can't understand in which order to learn from these?
Can anybody help me out?
The order of the entries on that page isn't organized so that you can gradually learn the concepts.
I'd rather advise you to try and go through the official Spring documentation first and take a look at the samples that come together with Spring. It'll give you an idea of the possibilities. Also, don't forget to make sure that you understand what the Inversion of Control (IoC) pattern is and why it's useful.
Here's what I'd recommend to someone starting out with Spring and IoC:
You should first try to use Spring in a very simple command-line application (hello world style).
Create an application context in xml and load it from your main method
Define a bean and retrieve it from your freshly loaded application context
Try to add a second bean definition in the application context and play with the bean definitions
Learn how to inject beans in properties, in constructors, ...
Play with those for a while in order to get a good feeling of what Spring core actually does for you (the IoC container) and how it can help you to decouple components in your code
Once you have a clear understanding of that, you can move on and read about Spring annotations and how you can either use xml or annotations (or even combine both approaches) to wire up your beans
You should only start using Spring in a Web application after having played around enough with the above. Once you have all that under control, then it'll be time to discover more advanced stuff and other Spring portfolio projects such as Spring Security, Spring MVC, Spring AOP, ...
The following are nice to have on the desk:
- Spring Configuration Refcard
- Spring Annotations Refcard
In any case, have fun! :)
I suggest you to learn from a books
I use Spring Recipes Second Edition to learn spring, the books is very technical and explain a good concept about spring
I have a GWT application where its RPC services are handled by a GWTHandler bean so that it can integrate with Spring smoothly. The application works. No problem with that.
My issue is I can't do any AOP logging with Spring. I like to log user activities from the GWT interface using AOP. (I could of course do it the old way of calling an RPC service for every action that a user does and log those action, but that is not the AOP way). I have to do it in AOP because that's the client's requirements.
I tried using the normal Spring AOP with a generic pointcut pattern "execution(* .(..))". It's able to capture all methods except for the GWT services. So in other words, it's useless. I could of course log the backend Spring DAO's using AOP but how do I know which RPC service it came from? These DAO's are used by numerous classes and methods (not exclusive to GWT).
I tried exploring GWT-ENT package. It looks good. However, it works on the client's side and your classes must implement Aspectable. This means requiring changes on all client classes on my GWT application. Furthermore, you can't use private methods since to handle AOP with GWT-ENT, you need to create your classes via GWT.create instead of the new(). Having private methods throws an error. I set-up a simple application and really private methods don't work.
I tried searching the GWT-SL package (where my GWTHandler came from). They mentioned about something about AOP, but the info is very scarce. Google didn't give me any solutions or examples.
I've tried everything I could think of and searched Google with all my efforts but I can't find a solution to my problem.
All I want to do is log methods from my GWT services via AOP. Let's say a client goes to the Report tab. Then he click on Delete button record. I want to log that activity via AOP.
I'm using GWT (with SmartGWT) and Spring/Hibernate stack.
Spring AOP will only advise public methods of beans in your Spring context, so GWT infrastructure is out unless you specifically instantiate it through the Spring container.
You could use compile-time weaving with AspectJ to wire your AOP into everything, but it might get a bit messy. It's also uncertain that it would work, unless you are compiling the GWT classes in question.
I'm gonna answer my question.
Instead of performing AOP logging on the GWT server implementations (which theoretically should work but in practice it's not), I decided to do AOP logging on the DAO layer. Just make sure you log the DAO not the Hibernate Session