Web Services Web Applications Wsdl

How to Successfully Consume Multiple Web Services in a Web Application

Web services play a crucial role in modern web applications, enabling them to interact with each other and share data seamlessly. However, a common challenge arises when trying to consume multiple web services that redefine some of the same classes within their WSDL (Web Services Description Language) files. This blog post will explore this problem and provide you with practical solutions to effectively manage these challenges when transitioning from a web site to a web application.

The Problem

When you have multiple web services that redefine certain classes, the primary issue that surfaces is handling the namespaces. In a web site structure, you have the flexibility to have the same classes under different namespaces, which eases the integration of multiple services. However, when converting to a web application, the situation changes significantly:

Namespace Conflicts: Multiple classes with the same name can lead to ambiguity and conflicts within the application.
Reference Management: In a web application, managing and referencing multiple services becomes cumbersome and prone to errors.

So, how can you effectively overcome these challenges?

Solutions

1. Manual Namespace Adjustments

One of the simplest, albeit less elegant, solutions is to manually edit the autogenerated Reference.cs files in your project. Here’s how:

Show All Files: Open your project in your development environment and make sure all files are visible.
Locate Reference Files: Find the Reference.cs files that have been auto-generated when you added the service references.
Edit Namespaces: Here are the steps to adjust the namespaces:
- Open each Reference.cs file and change the default namespace to your desired name.
- This will involve editing the namespace declarations at the top of the files and ensuring that they are unique.
Remove Duplicates: Make sure to eliminate any duplicate classes that might have risen due to service reference overlaps.

Pros:

Quick and straightforward for small applications.
Immediate results without needing additional tools.

Cons:

Prone to human error and can become tedious for larger projects.
Changes need to be repeated every time you update service references.

2. Use `wsdl.exe` for Proxy Generation

For a more robust solution, consider using the command line tool wsdl.exe, which can generate a single proxy for multiple services. Here’s how to do it:

Open Command Prompt on your machine.

Run the following command (modify it according to your services):

wsdl http://svr/foo.asmx http://svr/bar.asmx /namespace:Fnord.Proxies

Explanation of the command:
- Replace http://svr/foo.asmx and http://svr/bar.asmx with the actual service URLs you want to consume.
- The /namespace:Fnord.Proxies option allows you to specify a custom namespace for all classes generated, avoiding conflicts.

Pros:

Automated process reduces potential for manual errors.
Generated class files will have unique namespaces from the outset.

Cons:

Requires a bit of understanding of command line tools.
May still need some manual adjustments after generation.

Conclusion

Consuming multiple web services in a web application may pose several challenges, particularly concerning namespace conflicts. However, with a careful approach—either by manually editing the autogenerated files or utilizing wsdl.exe for proxy generation—you can manage these complexities effectively. Choose the solution that best fits the scale and requirements of your project, and you will be well on your way to a seamless integration of web services within your application.