Web Services

Introduction

This article enlists the various specifications related to web services. The list covers both the first generation specifications as well as second generation specifications.

The article also provides hyperlinks to the specifications and their maintainers.

In our second article of the series "Exploring Windows Communication Foundation", we explore the customization of the service and working with faults and errors. Specifically, we look at the following:

• Hosting the service in IIS/ASP.Net Runtime
• Customizing the details of a service contract, like the name of contract, namespace-URI to which it belongs etc
• Customizing the details of an operation contract, like the name of contract, it's parameters, order etc

Downloads

The code for the project is available for download at Edujini Downloads in the Windows Communication Foundation category.

Starting with this article, we shall explore various aspects of WCF.

Introduction

Microsoft .Net Framework 3.0 introduces, among other components, Windows Communication Foundation or simply, WCF. The framework allows us, the development community, to build more service-oriented application. It incorporates several Web Service related specifications, mostly driven by W3C and OASIS consortiums. I will just list a few of them:

1. SOAP 1.1, 1.2 with Basic Profile 1.1
2. WSDL 1.1
3. MTOM
4. WS Policy and WS Policy Attachments
5. WS Metadata Exchange
6. WSS SOAP Message Security 1.0, 1.1
7. WSS SOAP Message Security Username Token Profile 1.0, 1.1
8. WSS SOAP Message Security X.509 Token Profile 1.0, 1.1
9. WS Addressing 2005/08
10. WSS SOAP Message Security Kerberos Token Profile 1.1
11. WS Secure Conversation
12. WS Reliable Messaging
13. WS Coordination
14. WS Atomic Transaction
15. WS Federation

Starting with this article, let us tour various key aspects of WCF.

Downloads

The code for the project is available for download at Edujini Downloads in the Windows Communication Foundation category.

How do I access two separate methods of same class publishing multiple operations in a webservice with the state being maintained?

The answer to this question, put in the newsgroup, is making use of transaction techniques. What you are trying to say is that I would like to have operations being done successfully to indicate that my job is done.

Strictly speaking, the problem does not make a concrete sense in the realm of web services since multiple operations at an end-point may or may not be implemented by a single class. So, let me rephrase the problem so that it becomes technically correct w.r.t. Web Services.

I get a 405 error while working with ASP.Net based web service. The request synopsis is:

POST / HTTP/1.0
Host: my.machine.host.name
Content-Type: text/xml
Content-Length: NNNN
...

The problem is not anywhere else but with the request itself. To be able to appreciate the solution, one must understand the HTTP specifications.

1.0 version of HTTP does not specify any 'Host' header. It was introducted in 1.1. One needs to change the request to look something like:

POST http://my.machine.host.name/ HTTP/1.0
Content-Type: text/xml
Content-Length: NNNN
...

What is HTTP SOAP and how does it differ from HTTP POST as far as Web Services in ASP.Net are concerned?

To get an answer to the question, one must first have an understanding of the HTTP Protocol - how does it work.

HTTP Protocol allows, among other methods, two most widely methods - GET and POST. You may consider them as the commands given to the server to perform specific tasks.

How does the interoperability of Web Services between Java, PHP and .Net fare?

In this entry and may be a couple more to follow, I plan to bring out how the three leading web-platforms fare when it comes to Web Services. Few questions, not exhaustive by any means, that would be of interest may be:

• What level of support is available in individual platform?
• How good is individual platform when it comes to all standards and specifications around WebServices?
• How good is individual platform when it comes to inter-operability with others?
• What resources are available in terms of bundled libraries, additional libraries, 3rd party tools and libraries and documentation / tutorials thereof?

How do I use arrays in a Web Service?

Probably one of the more frequently asked questions regarding web services. I thought I will answer this prior to starting my discussion on comparing platforms.

Attempting to answer this question from the perspective of all three major enterprise platforms...

How to transfer files using Web Services?

There are actually multiple ways of doing so.

The first, simplest approach, is to send the contents of the file as a raw-string parameter. In case, the file content is binary, do not forget to base64 encode it.

The advantage of this approach is that you don't need to download any extra features / extensions / add-ons for any Web Service engine that you are using, be it on .Net, Java, PHP or whatever.

How to disable non-SOAP and non-Documentation Requests to ASP.Net based Web Services?

ASP.Net WebServices (ASMX handlers) are highly configurable in terms of the protocols that they can handle. By protocol, I mean the WebServices protocols like Get, Post, Document, SOAP-1.1, SOAP-1.2 etc.

The configuration section /configuration/system.web/webServices is handled by System.Web.Services.Configuration.WebServicesSection. Now, this section has a sub-section of procotols that is mapped to the Protocols property of the class mentioned.