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WebLog Posts in Category Web Services


WCF WS-Security and WSE Nonce Authentication



I ran into a Web Service last week that required WS-Security headers with an embedded nonce value. Unfortunately WCF doesn't support this particular protocol directly. Here's how to create custom credentials and a tokenizer to write out the customized WS-Security header.

Amazon Product Advertising API SOAP Namespace Changes



Amazon recently broke their Product Advertising API by rolling out a new service version at the same URLs of the old service, which resulted in immediate failure of service. It's an easy fix once you know where to look. Here's how.

.NET WebRequest.PreAuthenticate – not quite what it sounds like



On a few occasions I've dealt with Web Services that use - yuk - Basic Authentication and require pre-authentication on the very first request to the server with the server first sending a challenge. This is unusal for HTTP authentication which typically requires a challenge first and then a response with the auth information in the header. The latter approach is what the .NET client components produce by default. PreAuthenticate unfortunately is not quite true to its name and in order to provide true pre-authentication on the first request manual header manipulation is required.

Ambiguous References in DefaultWsdlHelpGenerator.aspx



Ran into an odd problem today where the default ASMX Web Service help page was blowing up with DataBinding errors due to ambiguous class names. Turns out that a custom control with the same name as a System component and a static method call resulted in ambigous reference errors.

WSDL Imports without WSDL.exe



A couple of weeks back I have been working on a Web Service client tool for COM clients. With the SOAP Toolkit DOA one of the things that old (for me most FoxPro apps of clients) apps need to do is access Web Services and .NET is really become the only viable option if calling a complex service is required. I’ve been swamped with work in this area recently (which isn’t a bad thing) but clearly a...

Monitoring HTTP Output with Fiddler in .NET HTTP Clients and WCF Proxies



Http debugging is immensely useful and Fiddler is a nice tool that provides many options and an easy to use interface to monitor HTTP requests to get maximum information about each request. In order to monitor requests of .NET clients like WebClient, HttpWebRequest or WCF or Web Service proxies you need a little additional configuration to get Fiddler to monitor these requests.

Debugging Http or Web Services Calls from ASP.NET with Fiddler



If you've tried to trace Http requests to Web Services or WebRequest calls in an ASP.NET application you've probably found although ASP.NET requests show up in tools like Fiddler or Charles, but the Web Service or WebRequest/WebClient calls do not. You can make this work however by modifying the proxy settings in web.config explicitly.

Watch out for XmlDocument.PreserveWhitespace when dealing with Digital Signatures



When creating digital signatures of XML documents its crucial that the Xml document settings on signing match the document settings that are expected for validating signatures. I ran into a problem where our signatures were failing with a vendor's site, due to the PreserveWhitespace property settings on our end and on the vendor's parser being mismatched.

Digitally Signing an XML Document and Verifying the Signature



Signing an XML document and then validating the digital signature of the document doesn't involve a lot of code - once you know how it works, but arriving there is quite the journey. This post describes setting up a certifcate for testing, signing an XML document with the Private key and then validating it with the Public key.

Web Service Interoperability? Not from where I sit...



I've been working on a lot of Web Service interop projects for the last couple of months all of which have been problem interfaces. For all the talk of interoperability I seem to be getting the short end of the "it just works stick" ending up with service that require endless fiddling to work properly for client access.

Invalid Service Urls in a WSDL Definition



Watch out for invalid URIs for the service address in a WSDL contract. When imported by .NET for Web References or WCF client proxies the invalid address can cause an instantiation failure in the proxy.

Generated Date Types in WCF and unexpected 'dateSpecified' fields



I just ran into a little issue with a Web Service imported through the WCF Service Utility. The issue revolves around dates imported for a service. In the WSDL the layout looks like this: <xsd:complexType name="NewEnrolment">   <xsd:sequence>    ...

Tracing WCF Messages



I'm working on a small problem that involves connecting to a Web Service and using WS-Security and I'm using WCF. It's not going well and so I've been trying to trouble shoot exactly what's going on. WCF is pretty good about reporting error messages and generally pointing you in the right direction...

WCF and segmented WSDL Files = Problems



Web Services in Windows Communication Framework publish their WSDL in a different format than ASMX based services did and this can cause some problems with 'legacy' SOAP clients. Legacy ahem in this case makes up a rather large set of tools that won't work with WCF services out of the box. WCF publishes the WSDL with discreet XSD schemas for each of the subsections which results in an XML document that pulls from the server. For example here's a simple WSDL output...

WCF, Web Service Clients and Http Debugging Proxies



I depend heavily on using Fiddler or Charles for helping me debug Http issues in general and both work great for typical Web development debugging in the browser. This is especially useful for AJAX applications since you can't 'see' the output that travels over the wire directly most of the...

Checking out Windows Communication Foundation Serialization



So I spent a bit of time this evening mucking around with WCF Serialization. The efficiency, complexity and usability of Serialization is a key component in using any technology that needs to communicate data over service/application boundaries and so this is usually one of the first things I take a look at. WCF is pretty impressive in this regards for its flexibility and implementation.

.NET Web Services and Visual FoxPro COM Object Threading Issues



I ran into an interesting issue today with a couple of ASMX Web Services that act as a front end for Visual FoxPro COM object for a client. The COM objects were blocking at times or worse in some cases cross talking and stepping on each other's environment. Turns out ASMX Web Services don't have an ASPCOMPAT flag so it takes some work to get Web Services to behave with STA components like those from Visual FoxPro


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