Doubt about the theoretical part of web services

Question

Hello, folks. I’m studying the web services part and I’m a little confused with the theoretical part. I was reading the article on this site

http://www.devmedia.com.br/introducao-as-tecnologias-web-services-soa-soap-wsdl-e-uddi-parte1/2873

And I was confused by the definition of "web service intermediary". I am developing a simple Android application, as if it were an exercise, that performs the registration and login of users.

In this program, I created the web service by Eclipse and an Android app to consume the web service. In this case, my web service and Android app are simply service provider and requester respectively?

Would anyone know of an example that has an intermediary web service?

And what would be the purpose of an intermediary webservice? because, thinking simply, the message could not go straight to the destination instead of going through another web service?

And in the case of my project that only has a web service and an Android app, can the Android app be considered an "initial sender"? In case, the Android app is considered a web service too?

I hope for answers and thank you very much to all who post a reply.

Answer 1

In this program, I created the web service by Eclipse and an application Android to consume the web service. In this case, my web service and Android app are simply service provider and requester, respectively?

If I understand the structure, yes. There is no intermediary here.

Would anyone know of an example that has a web service middleman?

An intermediary would be a third party service (outsourced) known in English as "third party".

Let’s take an example in the real world, for better understanding

A Web Service for sending SMS. When you use a third-party SMS sending service, you are using an intermediary. Because your app prompts a third party to send the message to the final destination. There is no direct communication between source and destination.

With intermediary

[origem] <-> [webservice terceiro] <-> [destino]

No intermediary

[origem] <-> [destino]

Another example of an intermediary is payment gateways. The gateways make the intermediate between the requester of the requisition and the final destination that are the financial institutions.