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Let me just preface this by saying I'm very new to the world of APIs and Web Services so please give me some slack if these questions are stupid.

So from what I understand, this is more or less how a web service (or web service architecture) works:

A web service provider describes its service parameters and how it to interface with the service in an XML document called the WSDL. The web service provider then registers with the UDDI. The "client" then queries the UDDI for relevant service providers. The UDDI returns multiple web service IP addresses and the client selects the best option. It then obtains that service provider's WSDL and proceeds to interface and utilize the web service.

My questions are:

  1. What exactly is a web service provider? I know a web service is essentially an API wrapped in HTTP (or some other transfer protocol) and it's used to facilitate communication over the internet. I also know that SOAP Web Services can utilize other transfer protocols besides HTTP, and WSDL and UDDI directories aren't used much outside of SOAP services. Is a web service provider just simply an application that is using SOAP web services?

  2. What is the "client" in this scenario? Is this a client web application or a browser?

  3. Why does the UDDI return multiple IP addresses for web service providers? Why doesn't the client just use the first web service it finds with the appropriate parameters, etc. ?

  4. How fast is all this happening? My dumbest question yet but are there developers manually querying the UDDI to find web services to integrate with their applications? Or is this all happening in a fraction of a second between computers?

Thank you so much. Couldn't find anything to address these questions online.

PFost
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1 Answers1

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  1. a) What exactly is a web service provider? I know a web service is essentially an API wrapped in HTTP (or some other transfer protocol) and it's used to facilitate communication over the internet. I also know that SOAP Web Services can utilize other transfer protocols besides HTTP, and WSDL and UDDI directories aren't used much outside of SOAP services.

Provider? probably the person, business, developer that provides some kind of service, like google, or microsoft, or amazon. If you write a service and provide it to other people by hosting it on a server of some sort, it would be you.

  1. b) Is a web service provider just simply an application that is using SOAP web services?

Not using a service, providing a service.

  1. What is the "client" in this scenario? Is this a client web application or a browser?

Could be anyone or anything, including your examples.

  1. a) Why does the UDDI return multiple IP addresses for web service providers?

It returns multiple bindings (where are end points for services) because it is common to have multiple instances of a service running, primarily to provide redundancy, load balancing etc.

  1. b) Why doesn't the client just use the first web service it finds with the appropriate parameters, etc. ?

That's up to the person that wrote the client or the user of that client. The first may not be the best choice (geography, latency, performance, etc)

  1. a) How fast is all this happening?

If employed, UDDI is usually one done once per client session or as needed if performance or operational needs dictate. This is basically runtime discovery. The downside is that you need to know something (where UDDI is and the lookup keys) before you can talk to UDDI, and then your target service.

  1. b) My dumbest question yet but are there developers manually querying the UDDI to find web services to integrate with their applications?

It could that way, but in practice, most people just use a search engine

  1. c) Or is this all happening in a fraction of a second between computers?

Usage statistics for UDDI are most likely very low to be honest however there's nearly no data on it in general. Difficult to determine

spy
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