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Promise Object in Windows Store App


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Promise in WinJS is an object, which ensure the app to run smooth without waiting for long running XHR call by using its asynchronous capability.

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Promise Object in Windows Store App

  1. 1. Promise Object Presenter: Nirmal Hota, Mindfire Solutions Date: 21/02/2014
  2. 2. About Me MCTS : .NET Framework 4, Web Applications MCTS : MS Dynamics CRM 2011 Customization and Configuration MCTS : Microsoft Dynamics CRM 2011 Applications TCAD : Titanium Certified Application Developer MS Dynamics CRM, Commerce Server, .Net, WinJS, PhoneGap, Titanium, Xamarin My Key Skills Connect me in : Facebook : Twitter : LinkedIn : Google+ : Blog : Skype : mfsi_nirmal Contact me in : Email : |
  3. 3. Agenda >> What is a promise >> How it works >> Advantages of promise >> Real life implementation (Demo) >> Q & A >> Some frequently used methods
  4. 4. What is a promise >> Schedule work for future >> Asynchronous programming approach >> Runs in background thread >> Foreground works without blocking >> Methods exposed by convention ends with “Async”
  5. 5. How it works Application Give me stuffs (via XHR call) MoveNext Promisestogetback Search I will manipulate the stuff if I get it HereisyourStuff Got it :) Let's manipulate
  6. 6. Some frequently used Methods >> then : Allows to define tasks to be done after promise fulfilled. >> done : Allows to define tasks to be done after promise fulfilled. >> any : Allows to define tasks to be done after any of the task performed among a set of promises. >> join : Allows to define tasks to be done after all of the tasks performed among a set of promises. >> cancel : Allows to cancel an in progress promise
  7. 7. then vs done >> Both of them are used after the completion of promised task >> Both the methods takes the same kind of parameters completed, error and in progress handlers >> “then” returns a promise object where as “done” returns an undefined >> In case any exception occurred in the promised block, “then” puts the error in the promise object and return it to outside. But “done” throws the same to outside as a normal exception. So better place for “done” is at the end of the promise chain
  8. 8. Advantages of promise >> No blocking of main thread for long running XHR calls. This can be handled in the background >> Ability to define the tasks after a long running XHR is over >> Can chain multiple calls >> Tasks can be defined to be done after the completion of multiple parallel processes or any process out the set processes
  9. 9. Real life implementation Demo
  10. 10. Question and Answer
  11. 11. Thank you
  12. 12.