Newbie Eclipse Question: Whats the difference between Manifest and Build Path?

[Perry Terrance]

I have a simple newbie question about the difference between Manifest and Java Build Path in Eclipse.

I have 3 J2EE Packages:

1 EJB Package
1 Web-Service Package
1 EAR Package which contains the above two packages

In the EAR, I see both the EJB Package and the Web-Service Package set under the Modules folder as a Services.war and a EJB.jar.

The Web-Service Package needs to access the EJB in my development environment so I goto the Properties window of the Web-Service Project and click on the Deployment Assembly option and add EJB.jar in the Manifest Entries tab. This would allow Eclipse to detect my EJB classes when I do import statements in the Web-Service classes.

However, I also found that I could do the same thing if I only add the EJB Project to the Projects tab of Java Build Path in the Properties for the Web-Service Project.

What exactly is the difference between these two ways and does it affect the behavior of the final EAR Package?

[Tom Reilly]

My educated guess is that the difference is when you want to run your code outside of Eclipse. If you haven't set up your manifest file correctly, the application will not run as desired.

[Jeanne Boyarsky]

Tom is 100% correct. The build path is used at compile time. The manifest is used when you deploy.