undefined function observer:start/0 ?

[linchengcs]

Hello, I am exploring cowboy and erlang. Everything works fine, but when I ran the "hello_erlang" example in the user's guide using command
./_rel/hello_erlang_release/bin/hello_erlang_release console
, and then in the erlang shell, I input the command:
(george@127.0.0.1)1> observer:start().
I got:
** exception error: undefined function observer:start/0

So, what am I wrong, and how can I get observer:start/0 started?

[essen]

It's not included in the release. Open relx.config and add ", observer, wx" next to your application's name in the list, then run make again and try, it should work then.

[linchengcs]

thank u for answer, I modified relx.config and its first row looked like:
{release, {hello_erlang_release, "1"}, [hello_erlang,observer,wx]}.

after making and inputing "observer:start()", the observer application started but got another error:
{error,{undef,[{observer_backend,sys_info,[],[]},
{observer_sys_wx,init,1,
[{file,"observer_sys_wx.erl"},{line,50}]},
{wx_object,init_it,6,[{file,"wx_object.erl"},{line,299}]},
{proc_lib,init_p_do_apply,3,
[{file,"proc_lib.erl"},{line,237}]}]}}

what should I do to fix this problem ?

[linchengcs]

I figured it out, the "runtime_tools" app should be added to start observer.

[essen]

Interesting, I did not know that one was also needed.

[essen]

Closing, cheers!