Edition 0 Updated to asp. Net core 0

Additional resources 
•
Scott Hanselman. ASP.NET Core RESTful Web API versioning made easy
https://www.hanselman.com/blog/ASPNETCoreRESTfulWebAPIVersioningMadeEasy.aspx
 
•
Versioning a RESTful web API
https://learn.microsoft.com/azure/architecture/best-practices/api-design#versioning-a-restful-
web-api
 
•
Roy Fielding. Versioning, Hypermedia, and REST
https://www.infoq.com/articles/roy-fielding-on-versioning
 

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CHAPTER 3 | Architecting container and microservice-based applications 
Microservices addressability and the service registry 
Each 
microservice has a unique name (URL) that’s used to resolve its location. Your microservice needs 
to be addressable wherever it’s running. If you have to think about which computer is running a 
particular microservice, things can go bad quickly. In the same way that DNS resolves a URL to a 
particular computer, your microservice needs to have a unique name so that its current location is 
discoverable. Microservices need addressable names that make them independent from the 
infrastructure that they’re running
on. This approach implies that there’s an interaction between how 
your service is deployed and how it’s discovered, because there needs to be a 
service registry
. In the 
same vein, when a computer fails, the registry service must be able to indicate where the service is 
now running. 
The 
service registry pattern
 is a key part of service discovery. The registry is a database containing the 
network locations of service instances. A service registry needs to be highly available and up-to-date. 
Clients could cache network locations obtained from the service registry. However, that information 
eventually goes out of date and clients can no longer discover service instances. So, a service registry 
consists of a cluster of servers that use a replication protocol to maintain consistency. 
In some microservice deployment environments (called clusters, to be covered in a later section), 
service discovery is built in. For example, an Azure Kubernetes Service (AKS) environment can handle 
service instance registration and deregistration. It also runs a proxy on each cluster host that plays the 
role of server-side discovery router.