Book Image

Reactive Programming for .NET Developers

Book Image

Reactive Programming for .NET Developers

Overview of this book

Reactive programming is an innovative programming paradigm focused on time-based problem solving. It makes your programs better-performing, easier to scale, and more reliable. Want to create fast-running applications to handle complex logics and huge datasets for financial and big-data challenges? Then you have picked up the right book! Starting with the principles of reactive programming and unveiling the power of the pull-programming world, this book is your one-stop solution to get a deep practical understanding of reactive programming techniques. You will gradually learn all about reactive extensions, programming, testing, and debugging observable sequence, and integrating events from CLR data-at-rest or events. Finally, you will dive into advanced techniques such as manipulating time in data-flow, customizing operators and providers, and exploring functional reactive programming. By the end of the book, you'll know how to apply reactive programming to solve complex problems and build efficient programs with reactive user interfaces.
Table of Contents (15 chapters)
Reactive Programming for .NET Developers
Credits
About the Authors
About the Reviewer
www.PacktPub.com
Preface

Sequence manipulation and filtering


Manipulation and filtering of sequence messages helps in the development of complex messaging designs. The most immediate and widely used operator is Where, which creates a routing sequence of messages already filtered based on its filtering predicate. We have already seen some of the manipulating or filtering factory methods in the previous chapter, such as the Take, Skip, Distinct, and DistinctUntilChanged methods.

Where

The Where factory method creates a new sequence that flows messages from another sequence only when a specific Where predicate succeeds. Here's an example:

//fixed-time interval sequence
var fixedTimeBasedSequence = Observable.Interval(TimeSpan.FromSeconds(1)); 
 
//convert the message  
//into time value 
var dateTimeSequence = fixedTimeBasedSequence 
    .Select(v=> DateTime.UtcNow ); 
 
//filtered sequence of times with even second value 
var filteredSequence = dateTimeSequence.Where(dt...