Question: I recently wrote a C program that is supposed to run in a Linux environment as follows;

```
#include <stdio.h>
#include <stdlib.h>

void main()
{
    system("notify-send -u normal -t 200 'You Have received a new message'");
    system("cvlc /home/ashenafis/Music/BabyMessage.mp3");
    return 0;
}

```

Compiled it and saved the executable in "/usr/sbin/play".

When I run it from the terminal it works fine, however it does not work when I try to run it from a PHP script using

```
<?php exec("/usr/sbin/play"); ?>

```

Is there something I am missing? Please help.

Answer: 
You can include the browser in the sequence diagram but you should not include UI details. You should just have the requests that can be initiated via the browser. This diagram is a good example:

<http://click.apache.org/docs/user-guide/htmlsingle/images/ajax/ajax-request-sequence-diagram.png>
In my view you are trying to show the sequence of interactions between objects for *purchase of a product*.

In this case the web page or the view **should not be in the diagram**. The page/view is a means of interaction with the user and might be displayed as an external call to a *endpoint* which will actually deal with a purchase request. So, probably the first/left-most *object* in your sequence diagram will be the controller/endpoint which receives this call.