Programming Erlang, 2nd Edition

Writing a Distributed Program

When I develop a distributed application, I always work on the program in a specific order, which is as follows:

1. I write and test my program in a regular nondistributed Erlang session. This is what we’ve been doing up to now, so it presents no new challenges.

2. I test my program on two different Erlang nodes running on the same computer.

3. I test my program on two different Erlang nodes running on two physically separated computers either in the same local area network or anywhere on the Internet.

The final step can be problematic. If we run on machines within the same administrative domain, this is rarely a problem. But when the nodes involved belong to machines in different domains, we can run into problems ...