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ReactiveList: ObservableCollection on steroids

If you ever build an MVVM style application before(using WPF, Silverlight, UWP,…) you probably used the ObservableCollection class.  It implements the INotifyCollectionChanged interface and can be seen as the counterpart of INotifyPropertyChanged. Through this interface the ObservableCollection notifies its subscribers about items being added, deleted, moved, …

Unfortunately the ObservableCollection is rather limited in it’s behavior and doesn’t fit well in a truely observable architecture. Luckily the ReactiveUI framework and more specificly the ReactiveList solve exactly this problem…

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Let’s describe a scenario I had to build that was hard to do using ObservableCollection and a walk-in-the-park with ReactiveList:

In our application we have to show a list of alerts and update the list when new alerts arrive. However alerts can arrive at a high pace and we don’t want to update the UI continuously but only when at least 5 alerts are raised.

In our original implementation we used a pull based mechanism combined with a timer to load the alerts every 30 seconds from the database.  Let’s see how easy it is to do the same thing with ReactiveList without having to fallback to polling and storing all data:

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