Fallback service

- [Narrator] Web services are not guaranteed…to function all of the time.…They may fail for various reasons,…such as time-out issues, or authentication problems.…We can try to avoid this problem by using multiple services.…If one service fails, we switch to another one.…This fallback strategy helps us…maximize our chances to deliver weather data.…The solution that we're going to rely on…is based on a well-known software design pattern…called "Chain of Responsibility."…This pattern organizes the potential…request processors in the sequence.…

The request travels through the sequence…until one of the processors handles it,…or until it reaches the end of the chain.…In our case, we need to build…a chain of network controllers.…Each network controller relies on a different web service.…If a web service fails for whatever reason,…the controller forwards the sent request…to the next controller if there is any.…To be at the sequence of controllers,…each controller should keep…a reference to the next controller.…

I'm going to need to add the back-up…