Application structure

Lennart Öhman lennart.ohman@REDACTED
Sun Apr 20 23:22:18 CEST 2003

a problem is that many general terms are used to denote
(different) specific things in different contexts. In the Erlang/OTP
world the following is usually meant by:

are collections of resources. Today these are usually code (modules)
and processes (or supervision structures (trees) of processes).
Applications are the smallest piece which is handled by the release-
handler. Hence the smallest piece which can be replaced. The idea
is that application shall be idependent in a way that it can be
reused in other places. Dependencies among applications are of course
allowed. All applications depend on stdlib and kernel for instance.

A system, in this context, usually referes to a collection of applications.
These applications are usually started through a boot-script file generated
by a tool in the sasl application.

When you start a "standard Erlang" system, you use a standard boot-script
which starts a system with the applications kernel and stdlib.

Best Regards,


Walter C. Reel III wrote:
> Many thanks.  That pointed me in a much better direction.
> On Thursday 17 April 2003 01:21 pm, Ulf Wiger wrote:
>>1) File structure
>>Organize your code into App/src, App/ebin, etc.
>>Try to keep the organization symmetric, e.g.
>>     /App2
> I've noticed (after you mentioned it) that the standard libraries in the OTP 
> distribution adhere to that same type of organization.  Although I may be 
> stretching it, would it be safe to say that applications closely resemble the 
> idea of a package in Python or Java?
> So, just to make sure I understand the terminology, a "system" is a collection 
> of interoperating nodes (which could be running on different machines) and a 
> "node" is an instance of the Erlang VM which could host multiple 
> application/server/etc. processes.  Right?
> (Of course my current place of employment uses those terms but with completely 
> different meanings ;)
> Cheers,
>  - Walt

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