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From "Hansen, Richard" <>
Subject RE: How do you detect that a service is down?
Date Mon, 11 Aug 2003 18:13:55 GMT
I have not tested this, but I would have expected some sort of Fault on the
client side. I am not exactly sure what you mean by not running though. It
seems to me that there are several types of "not running". Assuming HTTP:

1) The web server is down
2) Axis servlet unreachable
3) Axis can't find the service
4) Service has some unavailable resource that causes it to fail 
5) The call times out

In the first two cases I would have expected a client side fault with 404
errors. In the third, I would have expected some server side 500 error.
Number four depends the the service implementation.

Rick Hansen

> -----Original Message-----
> From: James Waldrop []
> Sent: Friday, August 08, 2003 11:11 AM
> To:
> Subject: How do you detect that a service is down?
> Hi there folks, I hope this is a simple question, but a search of the
> archives did not turn up a specific answer. I am using 
> client-side Axis
> to connect to a remove SOAP service (also Axis, but this is irrelevant
> for this particular question).
> I'm in the midst of putting in code to detect various error states and
> have run into an odd problem. It's not entirely clear how to detect if
> the service is currently down. I've been able to detect networking
> problems in connecting to the host via MalformedURLException, and was
> semi-expecting that a RemoteException would be thrown upon invoking a
> Call object that connects to a service which isn't running. Instead I
> get a null return value from the invoke(). This is less than ideal for
> my purposes, since when it's working the service can also return null.
> Perhaps the answer will be that my service needs to change to 
> not return
> null, in which case null is a valid way to detect Connection Refused
> errors, but I'm hoping there is a better way.
> Your time in answering this question is highly appreciated!
> James

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