Asynchronous Apex Salesforce World Tour Paris 2015

Asynchronous Apex
Paris June 25, 2015

Samuel De Rycke
Salesforce MVP
ABSI
@SamuelDeRycke
Samuel Moyson
Developer
ABSI
@SamuelMoyson
Speakers
#DevZone #SalesforceWorldTour #AsyncApex

Safe Harbor
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Synchronous vs Asynchronous
• Synchronous
• Asynchronous
Process 1
Process 2
Waiting for response
Process 1
Process 2
Continues working
Get response

• Synchronous
•Immediate and fast actions
•Enforce single, serial, transactions
•Normal governor limits
• Asynchronous
•Actions that should not block the rest of the process
•Processes where duration is of lesser concern
•Higher governor limits
Synchronous vs Asynchronous

Types of Asynchronous Apex
• Batch Apex
• Future Methods
• Queueable
• Scheduled
• Continuation

Batch Apex
Use when you want to:
• Process a big “batch” of records in smaller “batches” of records
• Each smaller batch is handled in a discrete transaction
• Monitor queue of batch jobs
• Batchable context with information about batch

Batch Apex
Start
Execute
Finish
global Database.QueryLocator start(Database.BatchableContext BC) {
//Query for data
return Database.getQueryLocator(query);
}
global void execute(Database.BatchableContext BC, List<sObject> scope) {
//Do some actions with data
//DML Statement
}
global void finish(Database.BatchableContext BC) {
//Give some feedback about statistics of batch
//Do post batch actions
}

Batch Apex
Process up to 50 million records
Monitor batch progress in the Setup User Interface
Admins can reorder batch priority with Apex Flex Queue
Maximum 5 concurrent batches processed (status Queued)
Not always easy to debug

Future Methods
• Execute methods that should not delay or respond to the
current Apex transaction
• Isolate transaction contexts and DML contexts
• Make asynchronous call outs to Web services
Pilot: Future methods with Higher Limits
• Set specific governor limits for a specific method x2 or x3

Future Methods
Executepublic class MyClass
{
public void myNormalMethod{
List<ID> recordIds;
//Synchronous logic here
myFutureMethod(recordIds);
// More synchronous logic
}
@future
public static void myFutureMethod(List<ID> recordIds)
{
// Get those records based on the IDs
// Process records
}
}
@future

Future Methods
Executed near instantly
Bypass mixed DML limitations
Pilot: increase limits for specific methods
Maximum 50 future methods per Apex invocation
Only accepts (collections of) primitive data types
Future methods can not invoke other future methods
Can not be invoked from Visualforce Constructors, Get & Set

Queueable Apex
• Start long-running operations and monitor them within the
current process or the user interface
• Pass complex types
• Chain asynchronous jobs

Queueable Apex
implements
Queueable
ID jobID = System.enqueueJob(new MyQueueableJob ());
public class MyQueueableJob implements Queueable {
//Other logic
public void execute(QueueableContext context) {
//Asynchronous logic here
//Optionally: enqueue another job
}
}

Queueable Apex
Executed near instantly
Unlimited depth of chained jobs (except for Dev & Trial orgs)
Use sObject and Apex objects as parameters
Maximum 50 jobs queued in a single apex transaction
When chaining jobs only 1 ‘child job’ is supported
Jobs can not be chained in test context.
Chained jobs do not support callouts (Winter ‘16 ?)

Schedulable Apex
• Schedule Apex classes
• Specify schedule with User Interface or Apex

Schedulable Apex
// Schedulable class
global class MySchedulable implements Schedulable {
global void execute(SchedulableContext sc) {
// Execute apex
}
}
// Schedule from Apex:
MySchedulable schApex = new MySchedulable ();
String sch = '0 15 10 * * ?';
String jobID = System.schedule('MySchedulable', sch, schApex);
implements
Schedulable

Schedulable Apex
Schedule from UI

Schedulable Apex
Execute Apex on scheduled intervals
Admins can manage the schedule from the Setup UI
Maximum 100 scheduled jobs at the same time
Using the Setup User Interface the minimum interval is 1 hour
Synchronous web service callouts are not supported

Continuation
–Make callouts from Visualforce pages
–Special one: synchronous asynchronous
Twitter demo
https://github.com/SamuelMoy/TwitterContinuationDemo

Continuation
Visualforce Continuation Webservice
startRequest
processResponse
Class
● Objects
● Methods

Continuation
// Visualforce page
<apex:page showHeader="true" sidebar="true" controller="TwitterController">
<apex:form >

<apex:commandButton action="{!startRequest}" value="Start"
reRender="result"/>
</apex:form>

<apex:outputText id="result" value="{!status} " />
</apex:page>
Visualforce

Continuation
// Action method
public Object startRequest() {
// Create continuation with a timeout
Continuation con = new Continuation(40);
// Set callback method
con.continuationMethod='processResponse';
HttpRequest req = new HttpRequest();
// Add callout request to continuation
this.requestLabel = con.addHttpRequest(req);
// Return the continuation
return con;
}
startRequest

Continuation
// Callback method
public Object processResponse() {
// Get the response by using the unique label
HttpResponse response = Continuation.getResponse(this.requestLabel);
// Set the result variable that is displayed on the Visualforce page
this.result = response.getBody();
// Return null to re-render the original Visualforce page
return null;
}
processResponse

Continuation
Integrate Visualforce with back-end systems
No long-running concurrent request limit for call outs
that last longer than 5 seconds
Visualforce page suspended until action completed
(= Synchronous)
Maximum 3 asynchronous callouts in one single Continuation
Maximum timeout continuation is 120 seconds

Testing Asynchronous Apex
• Invoke asynchronous Apex between the Test.startTest() and
Test.stopTest() methods.
• The Test.stopTest() method will execute all asynchronous and
scheduled Apex synchronously.
• Assert :-)

Recap
Batch Future Schedulable Queueable Continuation
High volume
of records
Near instantly
Primitive
parameters
Schedule jobs Chain jobs
Complex
parameters
Callouts in
Visualforce

Samuel De Rycke
Salesforce MVP
ABSI
@SamuelDeRycke
Samuel Moyson
Developer
ABSI
@SamuelMoyson
Q & A

developer.salesforce.com/trailhead

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Asynchronous Apex Salesforce World Tour Paris 2015

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