I'm confused. There are lot of servers(GlassFish, Tomcat, Apache,etc.,). But which one is used to implement easy for developing web application? Please suggest me. Thanks in advance.
Glassfish v3 is a slow starter (~30 secs), but its hotdeployments are fast. It happens in less than a second, regardless of what you've edited: JSP files or Java classes. At least, that was my experience in combination with Eclipse and the Glassfish Eclipse plugin. Things which may matter a lot. And as a bonus, you've the opportunity to play with the awesome Java EE 6 API.
Tomcat 6.0 is quick starter, in ~3 secs it's up and running. Hotdeploys of JSP files is acceptable, after ~3 seconds you can F5 to see the new one in browser. But hotdeploys of Java classes is sometimes troublesome. Sometimes it isn't picked up at all, or sometimes it takes too long that it's actually faster to manually restart Tomcat (which however takes "only" 3 seconds).
Take your pick. I'm just using both.