Chapter 4. Creating observable sequences

When people start learning about Rx, they usually ask, “Where do I begin?” The answer is easy: you should start with creating the observable.

In the next two chapters, you’ll learn various ways to create observables. This chapter is limited to observables that are synchronous in their creation. Chapter 5 covers observables that involve asynchroncity in their creation and emissions.

Because many types of sources exist from which you want to receive items, it’s not surprising that you have more than one way to create an observable. For instance, you can create an observable from traditional .NET events so you can still reuse your existing code, or you can create it from collections of items so it’s easier to combine it with other observables. Each way is suited to different scenarios and has different implications, such as simplicity and readability.

4.1. Creating streams of data and events with observables

The IObservable interface is the most fundamental building block that Rx is based on, and it includes only a single method: Subscribe.

4.2. Creating observables from events

4.3. From enumerables to observables and back

4.4. Using Rx creational operators

4.5. Summary