difference between a jndi lookup and java:comp look up?

[Ravi Kiran Va]

Hi Please tell me

what is the difference between a jndi lookup and java:comp look up?

When googled found this "Use a Direct Lookup when everything is in same JVM ,use java:comp when you are looking at a Resource on a different server."

But i have seen a lot of codings within the same JVM but still use java:comp look up .

so i am getting confused here .

[Balu Sadhasivam]

Ravi,

One thing is java:comp lookup is portable ,where as global JNDI lookup through context are not.

Say if you lookup datasource through JNDI in global context, when you change your underlying database , JNDI differs so does your code . where as if you use java:comp , change in web.xml / vendor specific xml alone.

[Ravi Kiran Va]

Balu , I did not understand .

If we use Global JNDI (without using java:comp) why does it require a change in the code ??

Please explain .

[Balu Sadhasivam]

this is just example.
Say If you change your database, your JNDI lookup changes , the code changes. where as the other way (java:comp) your xml alone changes