Creating Server-Side Logic with Controllers | Lightning Aura Components Developer Guide

Apex Server-Side Controller Overview
Create a server-side controller in Apex and use the @AuraEnabled annotation to enable access to the controller method.

AuraEnabled Annotation
The AuraEnabled annotation enables Lightning components to access Apex methods and properties.

Creating an Apex Server-Side Controller
Use the Developer Console to create an Apex server-side controller.

Using Apex to Work with Salesforce Records
Use Apex only if you need to customize your user interface to do more than what Lightning Data Service allows, such as using a SOQL query to select certain records. Apex provisions data that’s not managed and you must handle data refresh on your own.

Granting User Access for Apex Classes
An authenticated or guest user can access an @AuraEnabled Apex method only when the user’s profile or an assigned permission set allows access to the Apex class.

Securing Data in Apex Controllers
By default, Apex runs in system mode, which means that it runs with substantially elevated permissions, acting as if the user had most permissions and all field- and object-level access granted. Because these security layers aren’t enforced like they are in the Salesforce UI, you must write code to enforce them. Otherwise, your components may inadvertently expose sensitive data that would normally be hidden from users in the Salesforce UI.

Calling a Server-Side Action
Call a server-side controller action from a client-side controller. In the client-side controller, you set a callback, which is called after the server-side action is completed. A server-side action can return any object containing serializable JSON data.

Queuing of Server-Side Actions
The framework queues up actions before sending them to the server. Actions are grouped together into batches, and then sent to the server together. This process enables the framework to reduce network traffic by batching multiple actions into fewer, more efficient requests.

Storable Actions
Enhance your component’s performance by marking actions as storable (cacheable) to quickly show cached data from client-side storage without waiting for a server trip. If the cached data is stale, the framework retrieves the latest data from the server. Caching is especially beneficial for users on high latency, slow, or unreliable connections such as 3G networks.

Abortable Actions
Mark an action as abortable to make it potentially abortable while it's queued to be sent to the server. An abortable action in the queue is not sent to the server if the component that created the action is no longer valid, that is cmp.isValid() == false. A component is automatically destroyed and marked invalid by the framework when it is unrendered.

Action Limits and Considerations
Keep the following limits and other considerations in mind when using server-side actions.