I'm learning about web services and most of the resources I've been reading talk about registering your web service once it's ready for use by others. Is registering a web service required to use the service?
For example, let's say I have a web application on a company intranet and I create another web service app that retrieves some sort of useful information to be displayed on this private intranet site. Would this new web service require being registered just so my web app can use it or can the web app simply interface directly to the new web service (following the WSDL file) without the need of some sort of UDDI registry?
You can certainly use the service without the UDDI registry.
I have created several Web Services and have immediately used them without registering them. Registration gives others confidence that your Web Service is legitimate and descriptions of how to interact with those services.
Imagine doing development where you have to register any Web Service before using it. Yikes!
No, not at all.
You are probably talking about API directories you may register your WS at. Like UDDI or what it’s named. Entirely optional.
Nobody uses UDDI anymore. It's an idea whose time has come and gone.
It was thought that there would be public registries of web services that everyone would use to find a web service to meet their needs. That never happened.
How could either the service or the app know whether or not the service was registered?
Furthermore, why would they care?
If you're trying to use service orientation the right way, your web services should be registered within a service registry. The registry should contain the published contract of the services and any meta-data that helps the discovery process.
A different questions is: does a service consumer program need to look up a registry and dynamically bind the service it needs to call? NO, NOT AT ALL.
But then, what discovery process am I talking about? I'm referring to a human (developer, architect, etc.) who is designing/developing a program that needs to call a service. This person should have means to search what services are available in his/her organization. If not, the benefit of reusing services is compromised. Discovery is also about humans finding out there's a service somewhere in the IT organization that offers the functionality they want. In this case, the registry can be as simple as an html report that is created and updated manually or generated by parsing (xslt comes handy) the wsdl files.
来源：https://stackoverflow.com/questions/3738893/does-a-web-service-have-to-be-registered