Can a .Net 1.1 client call a .Net 2.0 web service? If so, how?

Question

We have finally upgraded our web services from .Net 1.1 to .Net 2.0/3.5. One of the clients that calls these web services is run as a windows service. It is probable that the windows service will not be upgraded until some time after upgrading the server at customer sites.

Is it possible to massage my .Net 2.0 web services so they will correctly service the calls from the .Net 1.1 client? In my test environment, I connect to the .Net 2.0 web service from a .Net 1.1 client and I receive a 401.1 error from IIS. The web service is set to anonymous access. The same credentials work when connecting to the .Net 2.0 web service from a .Net 2.0 client.

Thanks for your help,

-colin-

Answer 1

Web services are meant to be platform-neutral. If your web service was written properly, then any client, on any platform supporting SOAP 1.1, should be able to consume it.

One place where this can fall down is if your service is returning or receiving types specific to .NET. If you send or receive a DataSet, for instance, then there can be problems - DataSet is specific not only to .NET, but also to specific versions of .NET. There were many changes made in the area of XML and XML Serialization between .NET 1.1 and .NET 2.0, and you could eventually see one of those problems.

But I don't think any of those should get you a 401 error. Look into the event log and see if anything interesting was written about that error.

Answer 2

It depends on the service. If the .NET 2.0 service:

• Is configured to support SOAP 1.1
• Does not use WSE 3.0 (WSE 2.0 is OK)
• Does not use any nullable types (not supported in .NET 1.1)
• Accepts and returns only primitives or POCO classes (no DataSets, etc.)

Then it's compatible.

If you're getting a 401.1 error, but have no problem connecting with other clients from the same machine, then my guess is that the service is expecting something in the SOAP headers. What it's expecting, I can't tell you offhand; I'd have to see the service code/configuration.

Alternatively, it might just be a configuration issue on the web server. Without more details about the specific environments that can/cannot connect, it's hard to say.

Answer 3

As @Aaronaught wrote, The error can be that the service is expecting something in the SOAP headers. To analyse this, you could verify the wsdl generated (expand all files of web reference) or download the metadata via svcutil.exe. This will generate a proxy, that is used to call the web-service.
That way, you have more control over the proxy.

Example on how to use svcutil:

From command prompt: svcutil http://service/metadataEndpoint

Answer 4

Thank you for your responses. They were helpful in further diagnosing why it wasn't working. It turns out that everything does work and that the 401.1 response was misleading (but correct). Our problem was due to a change in the web services directory structure. Had I been paying better attention, I might have caught it before asking this question.

To answer my question: Yes. A .Net 1.1 client can call a .Net 2.0 web service and, in general, no additional configuration is necessary. Just make sure you're URI is correct.