Rx API in depth: Hot and Cold observables

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In this episode of the Rx API in depth, Wes talks talks about hot and cold Observables.

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The Discussion

  • User profile image

    I'm amazed there don't appear to be any so-called early-access / alpha books on Rx coming from Manning or APress. At least they're not listed yet. I'd really like to find something longer than 'just' a couple of blog postings that really digs into specifically Rx and reactive programming in general in .NET. These videos are great and I'm very grateful they're being make available, however for study purposes nothing beats the one-to-one, deep dive that the printed word delivers. Does anyone know when we might see a Rx book?

  • User profile image

    That is one of my new year's resolutions. 

  • User profile image

    I'm curious, what is the origin of the terms "hot" and "cold?"  Were other terms considered like "static" vs. "dynamic," or "immutable" vs. "mutable?"

  • User profile image
    Wes Dyer

    Hot = Running

    Cold = Not Running


    Static/Dynamic would be misleading.  Immutable/Mutable is also misleading.  Perhaps, the closest terms are Deferred / Not-Deferred or Latent / Active.


    The terms Hot and Cold came from whiteboarding and design sessions where we needed a term to describe the difference between something that running versus something that represents a thing that can be run.  We definitely didn't sit down and figure out a vocabulary, these things just happen.  I'm sure that at some point in time people will think about standard terminology, but we usually can't wait for that to happen.

  • User profile image

    As Wes mentioned above, I like to think of them as 

    Hot = Active

    Cold = Passive.


    I think we can do better than the explanation JVG gives here.

  • User profile image

    Ok instead of being part of the problem I thought I would put my 2c in. Angel


    Here is my post on Hot vs Cold Observables.




  • User profile image

    This is a very nice site.I like it very much!

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