First bits

As I said in a previous post, I'm learning Erlang via Joe Armstrong's book: Programming Erlang. This post is probably only meaningful if you caught the same error - if not, and you read it to the end, I tip my hat to you!

The error

In chapter 10, Distributed Programming, I hit a small snag following along with the Name Server example.

As instructed I start the first of the two nodes:

$erl -sname gandalf
Erlang (BEAM) emulator version 5.5.4 [source]
 [async-threads:0] [kernel-poll:false]

Eshell V5.5.4  (abort with ^G)
(gandalf@loulou)1> kvs:start().
true
(gandalf@loulou)2>

And then the second:

$erl -sname bilbo
Erlang (BEAM) emulator version 5.5.4 [source]
 [async-threads:0] [kernel-poll:false]

Eshell V5.5.4  (abort with ^G)
(bilbo@loulou)1>

So far so good, although I notice the shell has picked up the computer name loulou instead of localhost (although it's not mentioned anywhere in /etc/hosts - someone might like to explain to me how this works).

Continuing on with the example:

(bilbo@loulou)1> rpc:call(gandalf@localhost, kvs, store, [weather, fine]).

=ERROR REPORT==== 27-Jun-2007::18:28:22 ===
Error in process <0.38.0> on node 'bilbo@loulou' with exit value: 
{badarg,[{erlang,list_to_existing_atom,["gandalf@loulou"]},
{dist_util,recv_challenge,1},
{dist_util,handshake_we_started,1}]}

{badrpc,nodedown}
(bilbo@loulou)2>

"Weird" says I, but having noticed the node registered as @loulou I figure it's worth a shot:

(bilbo@loulou)2> rpc:call(gandalf@loulou, kvs,store, [weather, fine]).
{badrpc,nodedown}
(bilbo@loulou)2>

Plenty of surfing the interwebs ensued, all to no avail. Eventually I tried:

$erl -sname gandalf@localhost
Erlang (BEAM) emulator version 5.5.4 [source]
 [async-threads:0] [kernel-poll:false]

Eshell V5.5.4  (abort with ^G)
(gandalf@localhost)1> kvs:start().
true
(gandalf@localhost)2>

%%

$erl -sname bilbo@localhost
Erlang (BEAM) emulator version 5.5.4 [source]
 [async-threads:0] [kernel-poll:false]

Eshell V5.5.4  (abort with ^G)
(bilbo@localhost)1>

Which changes the node name to look exactly like the example. Voila! The example works as expected:

(bilbo@localhost)1> rpc:call(gandalf@localhost, kvs,store, [weather, fine]).
true
(bilbo@localhost)2> rpc:call(gandalf@localhost, kvs, lookup, [weather]).
{ok,fine}

I only wish the weather were actually fine - it's pouring here in Melbourne!

PS: I'm sorry for the lame syntax highlighting - I'm too lazy to write a function to switch it off. Maybe later...