# Problem with pengine\_rpc() call. Target app works from browser, but not from that call

**URL:** <https://swi-prolog.discourse.group/t/problem-with-pengine-rpc-call-target-app-works-from-browser-but-not-from-that-call/682>\
**Category:** Help!\
**Created:** [May 20, 2019, 10:22pm UTC](https://swi-prolog.discourse.group/t/problem-with-pengine-rpc-call-target-app-works-from-browser-but-not-from-that-call/682 "2019-05-20T22:22:01Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![prodog](https://avatars.discourse-cdn.com/v4/letter/p/57b2e6/32.png) [@prodog](https://swi-prolog.discourse.group/u/prodog)\
**Post date:** [May 20, 2019, 10:22pm UTC](https://swi-prolog.discourse.group/t/problem-with-pengine-rpc-call-target-app-works-from-browser-but-not-from-that-call/682/1 "2019-05-20T22:22:01Z")

</div>

I’m using: SWI-Prolog version 8.0.2

I have Pengines up and running successfully. If I point to the Pengines URL in my browser, the main page loads fine. I can then link to the Genealogist app and successfully run queries there.

However, if I try to execute a call from an SWI-Prolog interpreter window, it tells me that it can’t find the genealogist app:

```prolog
pengine_rpc('http://localhost:3030', ancestor_descendant(X, Y), [application(genealogist)]).

```

I also tried prepending the app name to the query:

```prolog
pengine_rpc('http://localhost:3030', genealogist:ancestor_descendant(X, Y), [application(genealogist)]).

```

But I still get an existence error.

Can anyone tell me why it works from the browser but not from the interpreter?

NOTE: I tried the test again on my Linux box where things seem to work better but in this case they did not. When I execute a `ancestor_descendant(X, Y)` call on that box, the same call that works from a browser, I get the following error:

```prolog
?- pengine_rpc('http://localhost:3030', ancestor_descendant(X, Y), [
| application(genealogist)
| ]).
ERROR: procedure `'c3e42777-26f7-4dcf-b9a2-4276f540f998':ancestor_descendant(A,B)' does not exist
^ Exception: (9) setup_call_catcher_cleanup('<garbage_collected>', pengines:wait_event(v(_6, _8), destroy(true), [listen('c3e42777-26f7-4dcf-b9a2-4276f540f998'), timeout(300), application(genealogist)]), _138, pengines:pengine_destroy_and_wait(destroy(true), 'c3e42777-26f7-4dcf-b9a2-4276f540f998', _138)) ? 

```