We have a web application that uses spring, struts and camel right now and there is a lot of customization we have done to allow us to know when beans are added to the context.
So, we have gotten to a point where we would like to remove struts from the application, because we are only using it to handle actions and we figure we could either use spring or camel to do the same thing. So I was able to get it to work with camel/velocity, but we didn't like how we really couldn't use the request object directly in the jsp (afaik, you have to put everything in the header of the Exchange and in the jsp you would do ${header.someReqVariableName}).
So we wanted to go the spring route, but since we load the context.xml directly, we have a provider that extends ContextSingletonBeanFactoryLocator and we pass the xml file name as a param, we haven't been able to figure out how to get the DispatcherServlet to work without giving it another configuration xml.
Is there a way to either:
Have camel use jsp for processing a jsp (and have all the usage of jsp tags)?
or
Have spring to see that a context has already been loaded and use that instead of having another new one?
or
Something better I have thought up?
You can use camel-jetty to expose HTTP endpoints, but I wouldn't use it for any complex web app development (JPS, etc). I'd use use Spring MVC (or similar) and use Camel for any complex routing/messaging requirements...
Here is another way, you can use the producer template to send the request to the camel context if you can get the reference of the camel context from the spring.
Related
So I Want to build projects using spring Boot directly as I'm under a bit of time crunch. Please help me out.
What you need to know about JSP: nothing. JSP is old and clunky, use Thymeleaf instead. But if you're building single page web apps you don't need any templates, you just need to know how to accept and return JSON.
Servlets: you need to understand the threading model, that there's only one servlet being traversed by multiple threads, and any instance variables will be accessed by all the http request threads. More than servlets you need to know filters, because Spring Security uses them.
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!
I am using Spring and JSF2 a lot and was wondering what the best way to integrate them is? Now i understand there are basically two ways to do this, but i have some problems with both:
a) Use normal #ManagedBean, and inject Spring-Services into that beans using #ManagedProperty: The problem is that i can't use Spring-AOP inside a #ManagedBean obviously, because it is not Spring-managed. I usually use an arround-aspect on every method annotated with my custom annotation #DatabaseOperation. Another example would be #Secured from Spring-Security and so on. I use a lot of AOP in my project and not beeing able to use them on "the top level" is really limiting for me.
b) Use SpringBeanFacesELResolver to make everything managed by Spring. On the pro side is that AOP works like a charm, but the cons are big too:
No ViewScope. I am not sure if i can trust custom view scope implementations like this https://github.com/michail-nikolaev/primefaces-spring-scopes on productive systems?
Serialization is not possible. It's already pretty complicated, but once i use AOP i can't get it to work because org.springframework.aop.aspectj.AspectJPointcutAdvisor is not Serializable
So my question is: How do you overcome this issues? How do YOU integrate JSF2 and Spring3.x? I have been using possibility b) mostly, but on my next project i need session replication..
Any further suggestions?
The main integration pain point of the two frameworks is that JSF is usually used in a stateful way. to make the integration the most seamless, you would have to let Spring handle the statefulness and page navigations aspects himself instead of JSF, as well as bean creation and scoping.
The second important integration point is at the level of the view expression language. We want to be able to access spring beans while building the view, which means the managed bean layer is no longer needed.
The best integration available for the two frameworks is provided by introducing Spring webflow, see here for further details. With SWF, JSF no longer manages beans itself, this is done by Spring. JSF does not manage page navigation anymore, this handled in the SWF flow definition.
Also the statefulness is handled by SWF. The flow definition XML file replaces large parts of the faces-config.xml for view navigation, transition actions, bean definition, etc.
Using the SWF JSF integration means that your faces-config.xml is mostly empty. Expression language accessing directly spring beans can be used while building the view, and a view scope is available.
If you want to keep a page isolated from the rest of the application, youcan create a flow with a single view state and self-transitions. An advantage of SWF is that it prevents duplicate form submissions via a POST-REDIRECT-GET mechanism that works transparently out of the box.
I am new to spring and I am creating a simple web application. I have been reading about contexts in Spring MVC.
I am using STS plugin for eclipse. I created a
Spring MVC project using the plugin.
Now I have three xml documents in the project, web.xml, root-context.xml and servlet-context.xml. These were created by STS for me.
In web.xml, dispatcher servlet is pointed towards servlet-context.xml and I understand the dispatcher servlets job is to create a web application context which knows how to resolve views and is a place for controller beans to exist.
Is my understanding correct? If so, what other job is accomplished by this context?
Now, there is a file called root-context.xml which has a component scan on my projects default package. My understanding is this context needs to have global beans which many servlets might use. Is my understanding correct? What else does this do? What kind of context is created using this file?
Now, I am further along in the project and I have several *-context.xml files (dao-context.xml, security-context.xml etc) which are loaded using contextLoaderListner (in web.xml). Is this a good idea? Or should everything go into servlet-context.xml? I think it's a good idea to have different contexts as it provides separation of concern. Comments? Also, what kind of context is created from these *-context.xml files? What is the proper folder location for these files?
Web.xml is for the servlet container like tomcat etc and all other xml files in the project are for the spring container. Is that correct? All these files are separated to provide separation of concern?
How many application contexts and web application contexts exists in the current scenario?
Why would anyone need more than one dispatcher servlet?
Why would anyone need more than one application context?
Thoughts? Comments? Corrections? Best practices?
The whole idea behind this design is to handle different architectural layers in a typical web application and provide for inheritance / override mechanism for beans across contexts. Each type of context in Spring is related to different architectural layer for e.g, web layer, service layer etc.
A Spring based web application can have multiple dispatcher servlet configured (although in majority of cases its a single servlet - but dispatcher serlvet is a servlet nonetheless and there could be multiple configured in web.xml). These can be configured to handle different url patterns. So obviously each is a different servlet and hence can have different Spring web Application context. Each of these can contain different configurations for Spring web layer like controllers,interceptors,view resolvers,locale resolvers etc. as these typically belong to the web layer of an application. All these configurations and beans are private to each dispatcher servlet so they are not visible to each other. Hence having a seperate spring web application context makes sense to enable this privacy. However there are other beans which are designed to be shared hence belong to a root context. So all the shareable things belong to the root context and it can be considered global for this web application.
Each dispatcher servlet inherits all the beans defined in the root context. However the important point to note is that the shared beans can be overridden by respective dispatcher servlet specific beans. So in web applications root context can be viewed as something which is inherited but can be overridden.
Well spring does not force you to have xml files in that way, you can very well work everything using only one xml file that would be servlet-context.xml and using only dispatcher servlet. Generally there are different files in order to define your service beans or dao beans, so this basically depends on your application design, for eg if you are using spring security you might want to add one more xml file something like security-context.xml like as I said it depends on design. You can actually eliminate context loader listener completely and still manage to do everything using dispatcher servlet.
Your question is too broad in scope, since you are new to spring may be you should get more details about spring containers and decide what suits your requirement.
I generally have my servlet-context.xml in WEB-INF and other configuration like service-context.xml in classpath, again this is no strict rule just how it suits me.
I am a Struts2 and Spring newbie and looking for some insight. When we load a web application we would typically want to cache some default look up data. e.g. if we wanted to store states or other data that does not change frequently and add it to the application context where we can access it across the application. What is the best way to realize this in a Struts2 application integrated with Spring? I read a bit about annotating with #PostConstruct which means I define my own class/method that would get a handle to the context by calling ServletActionContext.getServletContext() and then use setAttribute to add something. Is that a good way of going about things or is there a better option? Or would simply implementing a ServletContextListener be ideal?
Thanks for any input.
If you want to use the ServletContext, use Spring's ServletContextAware interface and then use an #PostConstruct or afterPropertiesSet method to add items to the servlet context.
This is simpler to use than the listener and integrates seamlessly with Spring, giving you access to properties files declared in Spring and any other beans.