Wednesday, June 22, 2011

Service API and Exceptions

Too often I see I am using a REST/SOAP API to talk to a third party system that frustrates me because of poor error messaging. Here's an example to illustrate a typical frustration:

Call: city_service.update_residence_address(city_dueler, new_address)
Response: <status>Failed</status><error>Invalid address</error>

But the address just seems right to me. So, I need to know specific reason about why the address is wrong. The error message leaves this critical detail. What happens next is, I look for the log files created by the city_service, conceptually supposed to be a third party hosted service. To do this, I SSH to the server, then cd to the logs folder and get lost in many of the cryptic log files. Then eventually I find a log and if I am lucky, I find something like the following:

InvalidAddressException at:...
Street number is not listed..

Now, I know I had an issue with the streer number. But I can see this only after I looked into the log of the thirdparty server. In an ideal case, I don't have an access to their server. Even if I have it, I cannot easily understand their logs and stack traces! In most API calls to third party applications I have had this frustration to varying degrees.

Here's a lesson learned:
Next time you expose an API for another app, expose error messages as specific as possible - so that, no details is left buried into your log files.