Promise Object

Presenter: Nirmal Hota, Mindfire SolutionsDate: 21/02/2014

About MeMCTS : .NET Framework 4, Web ApplicationsMCTS : MS Dynamics CRM 2011 Customization and ConfigurationMCTS : Microsoft Dynamics CRM 2011 ApplicationsTCAD : Titanium Certified Application Developer

MS Dynamics CRM, Commerce Server, .Net, WinJS, PhoneGap, Titanium, Xamarin

My Key Skills

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Agenda

>> What is a promise

>> How it works

>> Advantages of promise

>> Real life implementation (Demo)

>> Q & A

>> Some frequently used methods

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”

How it works

Application

Give me stuffs (via XHR call)

Move N

ext

Promises to get back

Search

I will manipulate the stuff if I get it

Here is your StuffGot it :)

Let's manipulate

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

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

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

Real life implementation

Demo

Question and Answer

Thank you

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