If we look back at the work we have done in this chapter on the sample application, we will notice that the architecture used is of sound quality. Our application is made up of a number of independent components. Each of these components conform to the Single Responsibility design principle and are dedicated to only one area of responsibility. We have created display components that are responsible for displaying a single area of the application screen real estate. We have also used the Domain Events design pattern to react to events within our application. One component may raise an event, but another component may be interested in this event. We are also using the State and Mediator design pattern to control the animation and display of the various elements of our screen real estate.

We have also discussed the use of various Observable techniques to help with the asynchronous nature of REST calls, and to respond to the series of events when we need to combine data from various sources. We have seen how to use the concatMap function to process an Observable stream one element at a time, and have also created Observable streams using the from and pipe functions. We have seen how to wait for multiple Observables to complete using the forkJoin function, how to notify multiple observers using Subject, along with using the filter function to filter Observable elements. We have built Angular unit tests to ensure that the code we have written to use Observable data streams is of the highest quality.

Hopefully, you have enjoyed the journey of building this sample application, and seeing the various techniques that we have discussed in earlier chapters, put into practice. We have finally arrived at an industrial strength, enterprise-ready, TypeScript built, single-page Angular, and Node application.