Setting Timeout Successfully on a Web Service Call
One of the annoying things about ColdFusion (yes even the Muse gets annoyed) is the sort of haphazard way it deals with timeouts. If the process you are timing out involves a call to an external service it's really a crap shoot whether or not it will work. Once CF hands off to the external service and starts its vigil waiting for the callback, the timeout value is largely ignored. Don't believe me? Create a long query to a DB Server and then pull the network cable while the query is running. The thread will usually continue to hang even if you have added a timeout value.
Recently Super Guru Jared Riley (Computer Services Inc. (CSI)) was lamenting this very problem with regard to a web service he was using. Because the web service would sometimes hang at the other end due to reliability issues his server was accumulating dormant ColdFusion threads which eventually would fill up the simultaneous request pool and begin to queue all other requests - effectively locking up the server.
It turns out a savvy developer named Jeff Nelson (also of CSI) came up with a solution for this particular issue. Before I share I must warn my readers that this is an undocumented solution that sets an underlying AXIS property. That means that subsequent changes to some future version of the underlying Axis libraries could cause this to error out at some point. The Muse has been known to use undocumented features successfully from time to time - but it pays to be vigilant when upgrading or patching. Also keep in mind this is only for web services. It will do nothing for Queries or cfmail etc. With that in mind here is the "fix".
Setting the timeout axis property
createObject('webservice', 'http://exampledomain.com/webservice.cfc?wsdl') />
<cfset webservice._setProperty("axis.connection.timeout",
javaCast("int",10000)) />
Now some of you might immediately say "hmmmm.... that's the connection timeout, but it doesn't really cover long running requests that occur AFTER the connection is made does it?" Jared has actually done a good bit of testing and claims that this property will timeout a request for either a connection reason or a time of process reason.
So if you are trying to solve this particular problem this might be an appropriate course of action. Now if we could just find similar settings for various DB Drivers my life would be complete.
Follow Up
For those of you who want to remind me that there already is a timeout property to cfinvoke that can be used here I would respond that that setting works correctly for creating the stub classes. In other words if ColdFusion can't compile the WSDL with the time alloted it will timeout. But it doesn't work for actual calls to the methods instantiated.
2 Comments
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Great tip! I just ran into a similar problem trying to enforce a timeout. My issue dealt with calling a third-party .Net assembly rather than a web service and found a hidden gem in CFTHREAD. I call to the assembly in a separate thread and then immediately join the page thread to that thread. The join action lets you set a timeout, meaning the join will always happen even if the thread has not completed. Then you can check the status of the thread and if it has not completed, you can terminate it and throw an error (fail gracefully).
There are definite limitations of CFTHREAD, including the fact that all variables that it can are passed by deep copy rather than by reference. Plus all threads created in the request must have a unique name, so you need to be careful when looping. But this solution worked great for me, and can be used for any code that can unexpectedly take a long time to process and you want to enforce a time limit. -
@seth,
Brilliant! I did something similar to proxy an HTTP request the other day. Love it!
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