CODEWITHSUNDEEP
erlangroutermochiweb
Ardem
Ardem

Reputation: 11

An error with Erlang router

I try to make a comet-server using Mochiweb like there.

If I do it from erlang shell, it's alright.

But If try to start 1st node with mochiweb from command line:

erl -pa ebin edit deps/*/ebin -boot start_sasl -sname n1 -s server +K true -setcookie secret_key -s reloader

And 2nd one with router:

erl -pa ebin edit deps/*/ebin -boot start_sasl -sname router -setcookie secret_key -eval 'net_adm:ping(n1@localhost), router:start_link().'

If I connect to mochiweb from browser I have this error

=CRASH REPORT==== 18-Jul-2012::19:04:45 ===
crasher:
initial call: mochiweb_acceptor:init/3
pid: <0.73.0>
registered_name: []
exception exit: {noproc,
                    {gen_server,call,
                        [undefined,{login,"234567e",<0.73.0>}]}}
  in function  gen_server:call/2
  in call from server_web:loop/2
  in call from mochiweb_http:headers/5
ancestors: [server_web,server_sup,<0.55.0>]
messages: []
links: [<0.57.0>,#Port<0.1406>]
dictionary: [{mochiweb_request_qs,
                  [{"session_id","234567e"},{"obj_id","page"}]},
              {mochiweb_request_path,"/polling"}]
trap_exit: false
status: running
heap_size: 2584
stack_size: 24
reductions: 1516

I think that problem is in this string from router.erl:

-define(SERVER, global:whereis_name(?MODULE)).

Because first part of -eval (net_adm:ping(n1@localhost)) was started without errors and I could see n1@localhost in nodes().. But the second part of -eval (router:start_link()) was not available for ?MODULE.

How can I resolve this problem?

Upvotes: 1

Views: 282

Answers (1)

Ivan Blinkov
Ivan Blinkov

Reputation: 2554

Looks like the gen_server that was supposed to be globally registered with name of current module (?MODULE is replaced with it) just has not been started yet. global:whereis_name(?MODULE) will return undefined right in this case, like you see in log you posted.

Find the part of your code that's supposed to do that (by grepping for ?MODULe and/or gen_server:start_link in that module) and make sure it was executed on the first node.

Upvotes: 0

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