Re: Exception handling strategy question

[Anne Thomas Manes]

Remko,   You don't have to return a Document in order to ensure language-neutrality. The whole point of SOAP and WSDL is to provide a layer of abstraction between your object model and your message structure that ensures language-neutrality. Axis lets you return whatever your application would like to return, and then Axis will convert that return into a document for you. No matter how you define your service (RPC or Document -- whether you marshal the message or you let Axis marshal the message), the client SOAP processing engine (e.g., .NET, MS SOAP, PocketSOAP, SOAP::Lite, Axis, etc) will receive a document, and that SOAP processing engine can automatically transform that document into the appropriate language objects on the client side (VB, C#, Java, Perl, etc).   It's fine if you want your application to work directly with the XML -- the Axis Messaging style lets you do so -- but I want to make sure that you understand that you don't have to do so to ensure language-neutrality.   When you return a fault, you don't return a response message -- you return a fault message. Axis can automatically capture an exception and return that exception to the client in a fault message, but that doesn't help much if the client isn't Java. Therefore you need to define a fault message for each of your exceptions, and then tell Axis to map the exceptions to the faults accordingly.   Anne   ----- Original Message ----- From: remko de knikker To: [EMAIL PROTECTED] Sent: Friday, June 27, 2003 1:31 PM Subject: Re: Exception handling strategy question Situation: OK, so far this helped, and pointed out the right direction in which to go. I had seen the SOAP Faults and understand now when to use them. I use the document/literal or message style of web services in axis, since I am sending XML only. I use the 'public Document method(Document doc)' signature, and I need to be language neutral, and therefor have to return a Document regardless. The Java Exceptions are indeed caught by the client, but I can't use this method. I managed to add a Fault to the SOAPBody object from the MessageContext and set its parameters, but as mentioned I need to return the Document, eg responseDoc, so the/any client can query this for Faults.... or do I have to deal with it differently?? Question: How do I append the Fault object to the Document to be returned?? Anne Thomas Manes wrote: There are four defined reasons to return a SOAP fault [1]: - VersionMismatch: the request didn't specify the correct SOAP namespace - MustUnderstand: a SOAP node did not understand a SOAP header that said mustUnderstand='1' - Client: the request failed either because it was malformed or contained invalid data - Server: the request failed because of some type of server error Remko's example requires an error code of Client. The error report should be returned in the fault <details> element. As long as you have Java on both sides of the wire, the SOAP system on the client should be able to simply rethrow the original exception (assuming that it has the exception class installed). But if you intend to support non-Java clients, you should map your various exceptions to specific SOAP fault messages. [1] http://www.w3.org/TR/SOAP/#_Toc478383510 Regards, Anne ----- Original Message ----- From: "George Jagodzinski" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Tuesday, June 24, 2003 3:22 PM Subject: RE: Exception handling strategy question if you are refering to business logic that happens after the request has been accepted I would say that the best way is to return some type of error report. I could be wrong but it seems like soap fault should only be thrown if there was a conformance issue. Someone please correct me if I am wrong. --George -----Original Message----- From: remko de knikker [mailto:[EMAIL PROTECTED]] Sent: Tuesday, June 24, 2003 3:22 PM To: [EMAIL PROTECTED] Subject: Exception handling strategy question when implementing a web service and a ws client, what is the general design principle for exception handling, when 1. when user entered a non-valid input value, for instance it doesn't exist in the database? Do I simply through a SOAPFault or is it better to append my own <doesnotexist> tag? 2. as a client, do I catch an xxxxException/Fault, do I look for the soapenv:Fault tag or do I have to look the webservice specific <wserror> tag?? What is the best design strategy here?? thanks, r