Question: I had just installed eclipse luna and I use the marketplace to install oracle package to use glassfish v4.0. Everything went ok but when I'm trying to install it they still show me an error at the server root path (Error: The specified directory is not a valid GlassFish installation.)...I don't know why? this happen even giving it a path. have anyone resolve this issue?.

Answer: 
I got caught by this trying to following along with the Lynda.com tutorial on web services with Java EE. You need to download and install Glassfish and then point the server root to the glassfish directory. Here are the steps I took:

1. download glassfish from here: <https://glassfish.java.net/download.html>
2. unzip the zip file: this is essentially the install step
3. navigate into the installation to the **glassfish** folder: this what you point eclipse to

The high level answer is here: [How do I use Glass fish server with eclipse luna for Java EE?](https://stackoverflow.com/questions/26723197/how-do-i-use-glass-fish-server-with-eclipse-luna-for-java-ee)
Possible duplicate of [How do I use Glass fish server with eclipse luna for Java EE?](https://stackoverflow.com/questions/26723197/how-do-i-use-glass-fish-server-with-eclipse-luna-for-java-ee)

However, you need to specify the "glassfish" folder under the extracted GlassFish files, for example ...\glassfish4\glassfish