Continuing execution even after error

hadoob024

I have this one issue. While logging in into our system, we call a routine called getToken(). This calls a routine on another server (used to be able to securely access documents). The issue we have is if that other server goes down, this call fails, and the user isn't able to login. I want to make it so that even if the other server goes down, users can still login and access our system (just not documents).

I know that I can't prevent fatal errors or even ignore them, correct (even with set_error_handler)?

Any thoughts? It's a simple call, here's all it is:

require_once('include/utils.php');
$token=getToken();

bradgrafelman

Not much we can suggest without seeing how the function works. For example, this:

hadoob024 wrote:
This calls a routine on another server

is highly ambiguous at best, and simply incorrect at worst. You can't just "call a routine on another server" - you have to establish some type of link/communication between them.

hadoob024

Sorry. That getToken() function makes a call to our Document server. The Document server sends a unique token back. We then build the links to our documents using this token. The issue is that if that Document server goes down, we never get that token sent back. And this getToken() routine is called at the end of our logging in process, so if this routine gets hung up because the Document server went down, the login process never completes.

Does that help? What I want to do is make it so that if the Document server goes down, and the getToken() function fails, I want the script execution to continue. This will allow the user to continue to operate in the website (minus access to the documents).

bradgrafelman

hadoob024;10988487 wrote:
That getToken() function makes a call to our Document server.

Again, "makes a call" is so ambiguous that it essentially means nothing (at least, it gives us no information). I can easily think of a dozen different ways to "make a call" to a remote server, and even then it's possible that none are relevant to what you're actually doing.

hadoob024;10988487 wrote:
And this getToken() routine is called at the end of our logging in process, so if this routine gets hung up because the Document server went down, the login process never completes.

Again, the devil is in the details. Saying that it "gets hung up" is again ambiguous and means nothing. What specifically is blocking in the getToken() function that causes execution to pause until a response is received from the document server? Depending upon the mechanism (see response above), there should be a way to introduce a user-defined timeout value.

Once that's done (or if it's done already?), you'd need getToken() to differentiate between a (successfully) received response and a timeout (and somehow indicate which happened via its returned value).

Finally, you can then use a conditional branch to handle the case where the document server has gone down and isn't providing responses (e.g. display an error, limit the features available to the user, etc. etc.).

hadoob024

The problem is that I don't have visibility to the other server. I have no idea what goes on there. Even the validation of the token I don't see. All I know is that I call the function, it then makes a SOAP call to the Document server, and returns a 36-digit GUID. I take this GUID and build the hyperlinks to the document.

In fact, I can't even modify the getToken() function. Here's the getToken() function though, which is all I have visibility to:

function getToken()
{
	global $sugar_config;

try {
	// set flag in php.ini file for soap call.
	ini_set("soap.wsdl_cache_enabled", 0);
	$options = array(
		'exceptions'=>true,
		'trace'=>1,
		'cache'=>false
	);
	$document_service_url=$sugar_config['document_service_url'];
	$client = new SoapClient($document_service_url,$options);
	$response = $client->GetToken();
	$token=$response->GetTokenResult;
} catch (Exception $e) {
   // echo "Caught Exception:".$e->getMessage()."\n";
   //$GLOBALS['log']->fatal("Caught Exception:".print_r($e->getMessage(),1));
}
return $token;
}

bradgrafelman

hadoob024;10988499 wrote:
it then makes a SOAP call to the Document server

Ah, see now we're getting somewhere - now we at least know how your PHP application is communicating with the remote server.

To that end, note on the PHP manual page for the constructor (link: [man]soapclient.soapclient[/man]) specifies one option that is relevant:

PHP Manual wrote:
The connection_timeout option defines a timeout in seconds for the connection to the SOAP service.

However...

hadoob024;10988499 wrote:
I can't even modify the getToken() function.

This is most likely going to be a problem. As it stands, getToken() doesn't specify a connection timeout value, and I have no idea what PHP does in that case (not timeout at all, perhaps?). What happens currently if the getToken() call never succeeds in connecting to the remote server?

Furthermore, even if it did timeout and the SoapClient threw an exception, your getToken() function would behave like this:

function getToken() 
{ 
    global $sugar_config; 

return $token; 
}

which is not only unhelpful but just plain bad coding (e.g. returning an undefined variable for starters).

hadoob024

now we at least know how your PHP application is communicating with the remote server

My bad. It's been a LOOOOONG day! 🙂

As it stands, getToken() doesn't specify a connection timeout value, and I have no idea what PHP does in that case (not timeout at all, perhaps?)

Yeah, I wasn't sure about that either.

What happens currently if the getToken() call never succeeds in connecting to the remote server?

I'm not sure. Wanted to test my stuff locally, but can't figure out how to reproduce the SOAP call and make it fail.

We implement SugarCRM and this is their code (which is why I can't modify it). I wonder if I can just copy the contents of this function into my code and add better error handling, maybe? All I know is that if the getToken() call fails, then the rest of the login procedure fails and the user can't log in successfully.

bradgrafelman

hadoob024;10988503 wrote:
Wanted to test my stuff locally, but can't figure out how to reproduce the SOAP call and make it fail.

Just use the same code, but try to connect to a host that doesn't exist, e.g. IP address 127.0.0.99 or something like that.

hadoob024

Makes sense. That way, I can try and determine the error and also be able to use the connection_timeout option as well.

Thanks man. Just left for the day, will try again in the morning and let you know how it went.

hadoob024

OK. What I've been able to do is make a copy of getToken() so that I can modify it. I've now modified getToken() to look like this:

/** 
 * Function to return token for document viewer service.
 */ 
function getToken()
{
	global $sugar_config;
	$token = '';

try {
	// set flag in php.ini file for soap call.
	ini_set("soap.wsdl_cache_enabled", 0);
	$options = array(
		'exceptions'=>true,
		'trace'=>1,
		'cache'=>false,
		'connection_timeout'=>15
	);
	$document_service_url=$sugar_config['document_service_url'];
	$client = new SoapClient($document_service_url,$options);
	$response = $client->GetToken();
	$token=$response->GetTokenResult;
} catch (Exception $e) {
   // echo "Caught Exception:".$e->getMessage()."\n";
   //$GLOBALS['log']->fatal("Caught Exception:".print_r($e->getMessage(),1));
}
return $token;
}

The issue is that the connection_timeout option only addresses the time it takes to wait to connect to the host. I just found out that when our Document service is hanging, that we can connect to it, however, we just don't get a response. I saw someone mention using:

ini_set('default_socket_timeout', 15);

However, I believe that over SSL and as of PHP 5.2.3 default_socket_timeout does not work for SSL connections. 🙁

Now I'm stuck as to how to modify getToken() so that it doesn't hang after making a connection but hanging on a response. Any thoughts???

johanafm

I've no idea if there actually are any settings for this that applies to SoapClient (read the doc yourself). However, I do know that it's possible to extend SoapClient and override ::__doRequest(). That function will be called after whatever specific function you call, such as SoapClient::getToken(), and it is at this point that the post request is actually performed.

So all you need to do in this function is create this post request yourself using cUrl, which allows you to set both connection and response timeout values.

hadoob024

Nice! Yeah, I just found this too by digging through the comments section of bugs.php.net:

http://www.darqbyte.com/2009/10/21/timing-out-php-soap-calls/