Rx Hands-On Labs published

Hi folks,

Yesterday, we released two hands-on labs on Rx both for .NET and for JS. The goal of those two documents is to present the reader with a gentle introduction into the subject, based on a series of incremental samples. This is based on a series on internal presentations we gave on the subject, being extended to various upcoming internal training events. Obviously we like to share this with the community, so here are the pointers:

• Rx .NET HOL
• Rx JS HOL

Enjoy! As usual, all feedback is welcome. The idea is to evolve those documents based on feedback from different channels.

Please note that the example of Generate on page 9 of the .NET version is based on the upcoming release of Rx in which we have changed the order of the arguments to match the for-loop construct.

Until that release is available, replace
    IObservable<int> source = Observable.Generate(0, i => i < 5, i => i + 1, i => i * i);
With:
   IObservable<int> source = Observable.Generate(0, i => i < 5, i => i * i, i => i + 1);

Thanks,
-Bart

[Edit 7/15/2010]

Hi folks,

We really appreciate the active feedback. Some suggestions have been incorporated now. The links have been updated to refer to the new documents that have the changes applied.

Thanks,

-Bart

Comments

• Anonymous
  July 07, 2010
  The comment has been removed

• Anonymous
  July 07, 2010
  Sorry... Excercise 2 step 7 that is... I guess we all make mistakes. ;)

• Anonymous
  July 07, 2010
  Rx JS HOL, page 27 says that   "function (term) { return searchWikipedia(term); }" eta-reduces to  "searchWikipedia(term)" but that should be "searchWikipedia" instead.

• Anonymous
  July 08, 2010
  Johannes, see the comment regarding Generate at the end of the blog post....

• Anonymous
  July 08, 2010
  On page 22,  the custom time stamp operator:        public static IObservable<T> LogTimestampedValues<T>(this IObservable<T> source, Action<T> onNext)        {            return source.Timestamp().Do(onNext).RemoveTimestamp();        } Should be: public static IObservable<T> LogTimestampedValues<T>(this IObservable<T> source, Action<Timestamped<T>> onNext)        {            return source.Timestamp().Do(onNext).RemoveTimestamp();        } Great document, great framework... keep up the brilliant work!

• Anonymous
  July 08, 2010
  Hi, congratulations to this HOL. That's how documentation should look like!

• Anonymous
  July 08, 2010
  This is terrific! I hope you guys will write more of these to cover advanced topics... but if not, this is still best documentation so far for Rx! Thanks.

• Anonymous
  July 08, 2010
  The comment has been removed

• Anonymous
  July 09, 2010
  Looks like an excellent intro so far! Minor typo (pg 7):  s/different form/different from/

• Anonymous
  July 10, 2010
  This was a very well done tutorial; very helpful avoiding getting lost in the sea of available Observable combinators.  More please!

• Anonymous
  July 10, 2010
  Exercise 2, step 9: Observable.Run returns void, but the example expects an "IDisposable subscription" return value.

• Anonymous
  July 10, 2010
  Excercise 2, step 10's parameter order appears to also be based on the yet unreleased version of reactive extensions.

• Anonymous
  July 10, 2010
  [Apologies if this is a duplicate, I received no success message the first time I clicked "Post".] Excercise 5, step 4: It seems better to .Throttle(...) before .DistinctUntilChanged(). With the order in the HOL, .DistinctUntilChanged() observes every typed value making it possible to get consecutive non-distinct notifications: Type "reactive" and wait for it to appear. Type backspace then 'e' within the throttle duration. Notice that "reactive" is displayed a second time. In the hypothetical spell-check application, this represents an unnecessary server call. If, however, .Throttle(...) is called first, .DistinctUntilChanged() only gets a chance to observe potentially submitted values. Consecutive duplicate values are not possible.

• Anonymous
  July 10, 2010
  Excercise 8, step 5: After discussing the confusing cardinality of the webservice output (the webservice returns an array of words), the query shown in step five confuses the cardinality of the webservice output by naming the query range variable "word" [singular] rather than "words" or "wordList" [plural].

• Anonymous
  July 12, 2010
  The first Windows Forms Rx sample does not work for me (page 14). ... moves.Subscribe(...) ... // blocked the UI I tried changing the current SynchronizationContext using SynchronizationContexts.WindowsForms but that didn't help either. Then I Intellisensed my way into SubscribeOnWindowsForms. That didn't work at first either. Only when supplying the actual form did it work without blocking the UI thread. ... moves.SubscribeOnWindowsForms(frm).Subscribe(...) ... what did I miss? :-)

• Bent

• Anonymous
  July 15, 2010
  I like your information. I have been looking for this type of information interesting and good

• Anonymous
  July 16, 2010
  Excellent job! One of the best documentation/explanations I have ever seen.. Kudos to the team

• Anonymous
  July 19, 2010
  Thx for this intro! As for js version: "If desired, clean-up of the event handler can be taken care of by calling Dispose on the object returned by the toObservable operator." I suppose Dispose should be called on object returned from Subscribe, not toObservable

• Anonymous
  August 01, 2010
  Very nice work (For the Framework and Document also ... ) I Appreciate the People Behind this Terrific Framework , Go Microsoft Research Go !

• Anonymous
  September 08, 2010
  I just want to let you guys know I heart Rx. :-)

• Anonymous
  December 09, 2010
  Excellent intro. Can we have a "303" on some of the topics mentioned in the "202", e.g. more on error handling, .Publish, etc.

• Anonymous
  February 07, 2011
  Page 14, 3.4, am getting an exception: A first chance exception of type 'System.EntryPointNotFoundException' occurred in System.Reactive.dll C:WindowsMicrosoft.NetassemblyGAC_MSILSystem.Reactivev4.0_1.0.4.0 Any ideas?

• Anonymous
  February 07, 2011
  My mistake.  Had an older Rx installed.  Uninstalled both and reinstalled and all good.

• Anonymous
  March 27, 2011
  One of the best HOLs I've ever seen. Well thought out, flows nicely.

• Anonymous
  May 26, 2011
  if the subscription order is guaranteed, why do the output of the sample code below differ? My understanding was that both subscriptions should have produced the same result. Am I doing something wrong?    public class A02BufferAndWindowEx    {        internal static void Run()        {            var numbers = Enumerable.Range(1, 26);            Console.WriteLine("Take the input in buffer size of 10");            var buffNumbers = numbers.ToObservable().Buffer(10);            buffNumbers.Subscribe(Print);            Console.WriteLine();            buffNumbers.Subscribe(Print2);        }        private static void Print(IEnumerable<int> nums)        {            Console.WriteLine();            Console.Write("Buffer size: " + nums.Count() + "tItems: ");            nums.ToObservable().Subscribe(PrintSingle);        }        private static void PrintSingle(int num)        {            Console.Write(" " + num);        }        private static void Print2(IEnumerable<int> nums)        {            Console.WriteLine();            Console.Write("Buffer size: " + nums.Count() + "tItems: ");            foreach (var num in nums)            {                PrintSingle(num);            }        }    }

• Anonymous
  April 25, 2012
  This HOL seems to be very out of date, e.g. System.CoreEx.dll no longer exists, and methods like subscriber.Run and Observable.GenerateWithTime have been removed. Can we have an updated HOL please?!