[SOLVED] What does these compile time warning means?

What does these compile time warning means?

I am newbie to erlang chicagoboss. I have just created a small project in erlang, and now wanted to update CB. Since I am updating only ChicagoBoss to its latest version i.e. 0.8.14. But While compiling/ running ./rebar get-deps getting following warnings.

I'm not getting what does it mean?

WARN:  Expected /home/user/workspace/ChicagoBoss/deps/mimetypes to be an app dir (containing ebin/*.app), but no .app found.
WARN:  Expected /home/user/workspace/ChicagoBoss/deps/cowlib to be an app dir (containing ebin/*.app), but no .app found.
WARN:  Expected /home/user/workspace/ChicagoBoss/deps/ranch to be an app dir (containing ebin/*.app), but no .app found.
WARN:  Expected /home/user/workspace/ChicagoBoss/deps/cowlib to be an app dir (containing ebin/*.app), but no .app found.
WARN:  Expected /home/user/workspace/ChicagoBoss/deps/ranch to be an app dir (containing ebin/*.app), but no .app found.

There're many warnings like these one. What I have understand some file .app not found. Since my questions are :

What does .app do, does it save any configurations?
Would it cause any issues?
I am not updating erlang, my current version of erlang is R16B01. Does those warnings have anything to do with the erlang version?

Solution

There's nothing wrong here; rather, these are just warnings that the rebar build tool issues when it starts to build a system but hasn't yet retrieved and built the project dependencies. The warnings won't occur again once rebar downloads and builds them.