Develop Reference

Add maven project to Dynamic Web Application

I currently have an opensource maven project that I have downloaded off github. The project includes 14 modules, all having dependencies with each other.
I am trying to create a RESTfull API using Tomcat 9 on eclipse to access the aforementioned project.
I started by creating a dynamic web application in eclipse. Is there any way I can add the project (GitHub project mentioned above) to the dynamic web application, so I can write a logic layer that can interact with the project.

If your goal for your second project is to consume the RESTful web services exposed by the first, then it doesn't need to actually interact with the first project at the code level. I would just create an entirely separate project in Eclipse. The first REST project you downloaded doesn't even need to be running on the same machine as your second project.

Serving multiple GAE modules from one development server?

I'm converting some backends to modules and am perplexed on setting up the development environment configuration. I'm using Java in Eclipse but not Maven. The architecture is very simple:
Front end module is default. Basic GAE/GWT app. Puts items on task queue.
Back end module processes task queue.
With the old backend architecture one debug configuration would start up the development server that would service the GWT DevMode UI and the backend task processing.
The crux of the issue is that the arguments to DevMode provide for a -war command line argument. Now that we no longer have a single war file (there is an ear containing two war files), we have to start them independently. This is fine, we can create a Launch Group that starts up the frontend and backend.
The problem is that each war file gets it's own
WEB-INF/appengine-generated/local_db.bin, which essentially creates two standalone applications. Am I missing something here? I need to be able to put a breakpoint on my front-end RPC service and in the servlet that handles task queue items in the new backend and have both of them hit in one debugging session.
Thanks for any thoughts.

If you follow the instructions here, this will create a modularized application structure in Eclipse, and not using Maven at all. You will need Eclipse WTP in order to have the required project types available (Enterprise Application Project and Dynamic Web Project).
The Eclipse project structure should look as follows:
<<Enterprise Application Project>> ear-app
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| (refers to)
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<<Dynamic Web Project>> app-module-1 "default"
<<Dynamic Web Project>> app-module-2 "any_name_2"
<<Dynamic Web Project>> app-module-3 "any_name_3"
<<Dynamic Web Project>> app-module-4 "any_name_4"
The value of "name" refers to the "module" element in appengine-web.xml, while the physical web project can have any name.
Please note that you need to switch into J2EE perspective in order to have the GPE WTP menu options available, they do not show up in the standard Java perspective.
Next, you need to link the EAR project to a new local server instance (of type "Google App Engine").
Only one of the web modules must be flagged as "default" in appengine-web.xml.
Upon deployment of the EAR to the local server, the datastore location is in WEB-INF/appengine-generated/local_db.bin of the default web module, and it is shared between the web modules.

I'm having similar problems figuring out how to implement multiple modules in the MyEclipse plugin for Google App Engine. The best information I've found just says to use Maven.
"Although Java EE supports WAR files, module configuration uses unpacked WAR directories only. App Engine's Java SDK includes an Apache Maven tool that can build a skeletal EAR structure for you." (source: https://developers.google.com/appengine/docs/java/modules/)
I also found this:
"A Maven project has a different layout than an Eclipse project. So, if you wish to use a Maven project with Eclipse, you need to do a bit more work. You have the following options:
1] Import a Maven project for App Engine into Eclipse as a Web Tools Platform (WTP) project, as described in Importing an Existing Maven Project.
2] Import the Maven project into Eclipse using an appropriate Maven integration plugin such as m2eclipse.
3] Set up two debug configurations, one for the Maven project in devserver (mvn appengine:devserver), and one for a Remote Java Application that you use to connect the Eclipse debug client to the devserver jvm. For details on how to do this, see ..." (source: https://developers.google.com/appengine/docs/java/tools/maven#creating_a_new_maven_app_engine_project_using_skeleton-archetype)
I know you said you're not using Maven, but might you consider trying it?

Managing Maven project in Eclipse with git repository

we recently migrated to Maven Build manager & git hub repository for our Java web-app. Also i switched to eclipse as eclipse has good set of plugins.
As a new bie, i am simply running mvn clean package from terminal at the code root directory. And then moving the compiled code i.e., /target/SNAPSHOT/* to tomcat/webapps/ROOT location.
And then starting Tomcat7 server. The process is time taking especially when i do code changes in Java & configuration .xml files.
I want to do it completely in IDE environment as i did earlier in Netbeans, update code -> build and run in debug mode, -> do code changes and then commit.
Heard of egit & m2e in eclipse for maven & github integration, but not sure how to use it.
Please walk me through the steps required in doing so. I am completely new to eclipse.
--
Thanks

You might want to consider using maven-jetty-plugin http://docs.codehaus.org/display/JETTY/Maven+Jetty+Plugin for running the webapp. You will not need to copy over stuff to tomcat. After configuring this plugin, you can simply run your application by doing mvn jetty:run
I generally do not like running webapps inside Eclipse. It's a personal prefrence, but it is always nice to have an IDE neutral way of building and running your applications. If you have m2e things should work simply fine. I have seen maven-jetty-plugin having hot pluggability where if you changed your web.xml, jetty would reload your application.

We use Git for version control and Maven for dependency management and build automation. Once your project has successfully imported into Eclipse and recognized as a valid java web project, you don't need either Git or Maven in order to build/run it inside IDE. Just creat a server using you existing tomcat installation, add the project to server, then select Run as > Run on Server.
The Complete Guide:
Creating a server
Adding projects to a server
Starting a server
For more details, check out Testing and publishing on your server.

How to integrate maven generated vaadin project into eclipse vaadin plugin?

Eclipse Vaadin plugin has cool autobuild feature. Just clicking "restart application" in debug console will bring up to date application version to live.
Unfortunately importing maven generated vaadin project(using m2e) and copy-pasting .project buildCommands and natures from vaadin eclipse plugin generated project does not works.
I'm unnable to "Run on server...", tomcat does not deploy app for unknown reason. I can see app in wtpapps folder but it still does not deploys.

You can build your Vaadin app as a regular Java library, by itself (not as a WAR, or anything complicated). Then do two things: Create another project that builds the actual WAR file, and create another project that sets up Jetty for direct execution (google for details on how to get Vaadin operating under Jetty standalone, using Jetty as a library). With that in place you can treat your Vaadin UI like a regular java program (fast, direct restart through the standard debug window), and still have it be a WAR file for deployment.
See this thread for details on how to set up Jetty (look for Launcher).

I have also stumbled upon this problem some time ago and eventually found this:
http://www.streamhead.com/maven-spring-vaadin-appengine/
It eventually helped me to get up and running after a scenario that has been very similar to what you have described.

How to have Eclipse Java EE automatically generate the exploded WAR for a web project?

I need to have a Java EE project generate a WAR file automatically - preferably exploded - as opposed to choosing Export -> War file.
I have played with the various server definitions but have not been able to get either the Java EE preview or the HTTP server to work, and before installing each of the external container specific servers I'd like to hear if anybody has made this work.
So, question is: Which steps to take to have a WAR deployment automatically created and maintained by Eclipse?
EDIT: This is Eclipse 3.5 Java EE, and it is a Dynamic Web project in Eclipse. I want the WAR file/tree to be easily copyable to a network drive to be accessible for the target host. It runs an embedded Jetty, but I am interested in the generic WAR.
MyEclipse can do this, but we are standardizing on plain Eclipse.
EDIT: This particular web application will run inside an embedded Jetty. Since this question was asked we have found empirically that we need to have the complete tree containing the application with embedded Jetty, war file (exploded) and all built by the Hudson server in order to avoid human steps in the build-deploy-process. The answer for us therefore is scripting with ant (using ant4eclipse).
EDIT 2012: The ant4eclipse approach proved to be generally too inflexible and fragile in the long run, so we have switched to Maven. This solved very many problems, this one included.

Make an ant task to build the war (and copy if you like). Then add an Ant builder to the project (project -> properties -> builders). As long as your project is configured to build automatically the war will always be upto date.
This would equally work with maven, or pretty much any other build tool.

You should be able to do this with "File" -> "Export", scroll down to "Web" -> "WAR File" and follow the instructions

Have a look at this question. It refers to 3.2 version, but I believe that it still holds, until up to 3.4 version at least. It seems there is no automatic way of doing the Export - War thing.
Consider the solution given by Pablojim and drop the Export facility.