I have two dynamic web projects - A & B. Project B references classes in Project A. Project A runs great on Tomcat locally. Project B runs on Tomcat locally too, but when I run it referencing Project A classes on Tomcat, the classes from Project A are missing in Tomcat and thus throwing a class not found exception.
Since I cannot jar the Project A files, how can I get the classes from Project A to a local Tomcat deployment so that Project B can run when referencing Project A classes?
If two web applications share some common classes then these classes should be refactored out of the web application code base and put into a separate library (jar file). This jar can then be added to your web applications as a dependency.
Related
I have a JAVA EE Project, containing both EJB and WAR projects inside of it.
I want to be able to access WAR project class from the EJB project class.
I have access the other way ( I can access ejb class from war).
Is that possibble? How can this be done?
Thank's In Advance.
I assume that you have got an EAR with two modules inside, WAR and EJB JAR. As both modules are independent, they shouldn't depend on each other. What you want to do is possible via MANIFEST.MF Class-Path entry in module META-INF folder, but I strongly discourage you to do so.
You can re-factor you application to following structure:
EAR/
ejb-app.jar
war-app.jar
lib/
common-libraries.jar
Just putyour common libraries to separate JAR (regular java project), and add it to ejb-app and war-app classpath.
Alternatively you can implement EJB's in WAR project as they are supported in WAR since Java EE6.
My Project has 2 java files (A.java and B.java in same package). A.java uses methods in B.java. And, an external jar has been added in the project build path. In order to create a web service (bottom up) from the class, I created a new Dynamic Web Project in Eclipse with axis2 as the runtime platform, and imported A.java and B.java source files. Next, since all my methods that need to be exposed are contained in A.java, I right click on it and created web service using the standard settings. When I deploy the web service on my apache, I get "Fault Service" and a few ClassNotFound Exceptions for some of the classes in my external jar file (I have already imported it as an external jar).
Does the external jar needs to be imported in another way?
I would expect a deployable application to be self contained, hence the "external" jars need to be included in my application. In my environment (WebSphere) you can also deploy external jars in some "shared" places and special directories, but for simple cases I prefer my app to be be self contained.
So, either include the JARs in WEB-INF/lib or package the app in an EAR file, place the JARs in teh root of the EAR and adjust the Manifest for your WAR to refer to those JARs.
I have a Java Project, for which I'm now creating a Web interface, using a Dynamic Web Project from Eclipse. The Web project consists of a single servlet and two JSP's. Something like this:
/JavaApplication
/src
/lib
/resources
/WebApplication
/src
/Servlet.java
/WebContent
/WEB-INF
index.jsp
other.jsp
Now, I need to reference JavaApplication from WebApplication, in order to use its classes to process web requests. What's the best way to accomplish this ? My idea is to create a .jar of the JavaApplication, containing all the .class files, /resources, and /libs. In this way, I could include the .jar in the web application, and I could have a single .war file that contained the entire application.
What do you think? How is this problem typically solved ?
Note: I don't want to convert the Java Project into a Web project.
In Eclipse project properties, add the project to the Java EE Module Dependencies (Eclipse 3.5 or older)
or Deployment Assembly (Eclipse 3.6 or newer) entry in the project properties.
This way Eclipse will take care about doing the right thing to create a WAR out of this all (it will end in /WEB-INF/lib). No other configuration is necessary, even not some fiddling in Build Path.
Under Eclipse, you can declare Project References for a given project, the web application in your case. To do so, right click on your web application project, then go for Properties > Project References and select the JavaApplication project. This should allow you to call code from the JavaApplication project from the WebApplication without having to build a WAR. This is a solution for development.
For standard deployment (outside the IDE), you should indeed create a standard WAR. To do so, you'll have to package your JavaApplication as a JAR including the .class files and the files under /resources but not the libraries it depends on (JARs under /lib). These dependencies will actually end up in the WEB-INF/lib directory of the WAR, beside the JAR of your JavaApplication. These steps are typically automated with tools like Ant or Maven.
Connecting java app to web app for development :
right click on web project :
properties>project references> add the java project you want to refer
Now in properties tab of web project go to
properties>deployment assembly> add the project manually and run the app
Consider moving up to EAR level, if your web container supports that.
The tricky part with shared code is where should the common code be put. A copy pr web application? A copy in the web container? Overdoing the "share these classes" might end up in class loader problems.
If you are creating two separate web applications refactor common java code into a separate Eclipse project and refer to it from both WAR projects.
EDIT: Apparently I have misread the problem description, and thought you asked about an existing and a new web application sharing code.
If you have an Eclipse project with your application, and another with your web frontend, then you can let your application export the necessary resources which the "Export WAR" in Eclipse Java EE can wrap up in a jar file and put in WEB-INF/lib for you. You need to say this explicitly with a checkmark in Properties -> Java EE Module Dependencies for your web project. Expect you have to experiment a bit - this took me a while to learn.
Typically you would create an API interface using remote service beans from the Java application that expose the methods that you want to invoke in the web application. You would include a proxy of the API interface with your web application that calls the remote service bean in the Java application. Remember that you will need to register the remote bean in the web.xml file.
I have a web application - deployed on Tomcat.
It has two modules
Module A and Module B
Both have java code as well as UI component (struts\JSP etc.)
Functionally, Module A is independent an doesn't depend upon Module B
For ModuleA:
We create a war for Module A and deploy it as ModuleA.war
Now Module B depends upon Module A
We so "merge" the two modules into ModuleB.war
This involves merging the web content directories into one
We were feeling uncomfortable with this whole process of merging and wondering if there is a smart way to do this ?
We are also considering putting all the web content in one of teh modules - say Module A
and just keep the java code in ModuleB
Any suggestions ?
This is one of the java problems.
Say you app A is the public website, say your app B is your admin, but uses same database, same bizlogic classes,etc.
I found this problem all time. My approach might help you.
module A will have classes related only to project A
module B will have classes related only to project B
mod A and B will share a .jar file who contains all related classes, you can deploy it in TOMCAT/lib or if you want maintain it individually, deploy it in each app MYAPP/WEB-INF/lib
So I started with a web services project (just a dynamic web project) that builds and debugs correctly from eclipse. We've pulled a chunk of common code out that we want to put into a shared library so now those classes are going into a separate jar project that the web project references.
On the web project, I did Project->Properties->Java Build Path->Projects->Add and added the jar project. And this correctly solved all the compile-time classpath problems and everything builds fine. But at runtime, when the tomcat server fires up, spring attempts to inject some of the classes contained in the jar file and I get a NoClassDefFoundError.
My .class and properties files and the contents of my META-INF directory are showing up in the ./build directory, but my WEB-INF/lib directory seems to be referenced in-place, and the jar dependency doesn't get copied in to it to show up as part of the Web App Library.
What is the magical incantation to tell eclipse that the other jar project needs to be available to tomcat at runtime? From our ant build script, we first just build the other project into WEB-INF/lib and everything works fine, but not for eclipse debugging.
I figured this out after spending some time on it. If you are in Eclipse Helios , go to properties > deployment assembly > add > project and select the dependent project you wish to add.
Java EE module dependencies would solve this problem.
You have already done the task of extracting your common classes into its own project, possibly because other projects depend on these classes. Either way, you'll have to ensure that this is a Utility project (appears under Java EE in the project wizards), and not just a plain Java project.
One that is done, you can proceed to add the Utility project to your build path (compile-time path) as you have figured out.
The additional (final) step is to establish a Java EE module dependency between your Dynamic Web project and the shared library, which causes the utility's classes to be placed in WEB-INF\lib during deployment, and even during export of the WAR. To do so, visit the dynamic web project's properties, and browse to the Java EE module dependencies. Ensure that your utility project is selected here. Redeploy/publish your application and you should be good to go.