Discussion on Apex Trigger & Scheduler Framworks

1. Apex Triggers & Scheduler Frameworks
By
Sumitkumar Shingavi
@sumit.shingavi

2. Agenda
 Design discussion on
 Apex Trigger
 Batches / Schedulers
 Open house : Share your experience!
 Twitter handlers: @sumit.shingavi @Prasanna
@thisisnotapril @salesforceDevs @TheChrisDuarte
@kevindrapatel

3. Few Questions : Apex Triggers
 When to use apex triggers?
 When to use before / after trigger?
 How many triggers you have built so far?
 What is the pattern of code you have used?
 What is batch size a trigger can handle when
bulkified?
 Do you ever seen a need to de-activate your triggers
during historic data migration for enterprise scale
projects?

4. 3 ways to write Apex triggers?
 Modular Programming Approach – Simplest! (70%)
 Factory Pattern (20%)
 Abstraction of Handlers (10%)
 When there are multiple handlers for a object
 Sequencing of handlers is required in execution
 Dynamic instance creation is required.
 CustomSettings__c cs = CustomSettings__c.getInstance('Vehicle');
 Type t = Type.forName(cs.className__c);
 Vehicle v = (Vehicle) t.newInstance();

5. Apex Triggers – Keep it Simple!
 ONE trigger per object
 Logic – less triggers
 Context specific handler methods
 Use advance inline queried for loops wherever possible
 Right naming conventions
 Entry criteria – No open entry points / method calls!
 For Modular Programming approach, follow structure as:
 AccountTrigger
 AccountTriggerHandler
 AccountTriggerActions
 AccountTriggerTest
 For code visit: https://cloudmastro.blogspot.com

6. Factory & Abstraction of Handlers
 Factory pattern
 You should have an interface which declares all handler
virtual methods
 Handlers are instantiated dynamically
 When it actual goes down, you need to pass 1 object at a
time by iterating over List<sObject>
 Abstractions of handlers
 Also called as Dispatcher pattern
 Used when you want heavy segregation between your
events
 Difficult to maintain

7. Advantages of Proposed Framework
 Order of execution
 Separation of concerns
 Control over re-entrant code
 Clear organization and structure
 Singleton frame
 Make implementing new logic very easy
 Simplify testing and maintenance
 What not to do!
 Do not use static variables to control re-entrant code

8. Apex Scheduled Batch Apex : Quick Highs
 You can have a single class Schedulable and Batchable
 Default batch size is 200 but can be raised up to 2000
 It is asynchronous so no guarantee on time
 100 scheduled apex jobs at a time
 While writing unit tests; you should put asserts after
Test.stopTest()
 Governor limits applied separately for batch and schedule
 10 webservice callouts per batch
 Database.stateful, Apex Flex Queue (100 jobs in one shot)
 Serial Batches: For this, you need to call next batch in
final() method of current batch.

9. Thank you!
Blog:
https://cloudmastro.blogspot.com
Twitter: @sumit.shingavi
Linkedin: Sumitkumar Shingavi