The Complete Salesforce API Landscape

Interview Quick-Revision Guide

The Complete Salesforce API Landscape

Categorized architecture, strict use cases, and rapid-recall patterns for technical interviews.

To ace a Salesforce Architect or Developer interview, you must look past basic API definitions. You need to know why you would choose one API over another based on data volumes, transaction boundaries, and system constraints. Here is your quick-revision blueprint.

API Landscape At-A-Glance

  • Core Data APIs: For standard CRUD operations on CRM records (REST, SOAP, Bulk 2.0, Pub/Sub, Composite).
  • Custom Development APIs: For exposing custom Apex backend logic (Apex REST, Apex SOAP).
  • Metadata & Tooling APIs: For modifying platform structures, configurations, and CI/CD operations.
  • Specialized UI & Sub-System APIs: Tailored for frontend frameworks, UI data bundles, and specific clouds (GraphQL, UI API, Connect REST).
Category 01

Core Data APIs

REST API (Synchronous)

Lightweight HTTP-based framework interacting with individual rows via JSON or XML payloads.

Use Case:Real-time, lightweight web or mobile application integrations.
Benefits:Easy to test, natively handles JSON, stateless, highly scalable for small transactional loads.
Interview Scenario: "A customer fills out a lead capture form on your corporate website. The website triggers an immediate REST POST request to instantly instantiate that Lead record inside Salesforce."

SOAP API (Synchronous)

Rigid, strongly typed, contract-based framework utilizing strictly XML payloads and WSDL files.

Use Case:Legacy system integrations or high-security financial middleware tracks.
Benefits:Strict type safety via WSDL mapping prevents runtime data schema format mismatches.
Interview Scenario: "An on-premise banking ledger system needs to push accounting logs into Salesforce. The middleware uses the enterprise WSDL contract to strictly enforce data parameters before dispatching."

Bulk API 2.0 (Asynchronous)

High-throughput background loading framework designed to digest raw CSV text streams.

Use Case:Data warehouse syncs, initial system migrations, large data backups.
Benefits:Bypasses standard transaction limits, automatically fragments files up to 150 million rows daily.
Interview Scenario: "Your company acquires a competitor and you must bring 3 million historical Account rows into your system without hitting execution timeout caps."

Pub/Sub API (Event-Driven / gRPC)

Bi-directional, event-driven architecture streaming Platform Events and CDC via HTTP/2 channels.

Use Case:Real-time replication pipelines or loosely coupled messaging middleware setups.
Benefits:High performance via binary Apache Avro formats; eliminates heavy custom REST polling loops.
Interview Scenario: "An external inventory system must spin up an order packaging line the exact millisecond an Opportunity is marked Close-Won inside Salesforce."

Composite API (Synchronous)

Orchestration engine packing up to 25 separate execution threads inside a single HTTP roundtrip.

Use Case:Deep hierarchical inserts (Parent-Child-Grandchild operations) in one transaction.
Benefits:Saves API limits drastically by passing outputs from step A dynamically into step B as inputs.
Interview Scenario: "An external billing system wants to instantiate a new customer Account, attach an active Contact, and log an onboarding Task simultaneously in a single transaction call."
Category 02

Custom Development APIs

Apex REST & Apex SOAP APIs

Custom exposed web services crafted using @RestResource or webservice global modifiers in Apex code.

Use Case:Exposing custom server-side validation or combining multi-object actions that standard endpoints can't handle.
Benefits:Enforces complex, customized server-side logic and validation before any record changes are applied.
Interview Scenario: "An external platform needs to verify inventory allocation before creating an order line. A custom Apex REST endpoint checks inventory, queries related fields, and creates the record in one clean block."
Category 03

Metadata & Tooling APIs

Metadata API vs. Tooling API

Structural control endpoints interacting with environment configuration schemas, layouts, and system customization files.

Use Case:Metadata: Core deployments / DevOps pipelines.
Tooling: IDE development, code editors, granular log retrievals.
Benefits:Automates deployment management; Tooling API provides fine-grained, fast access to smaller configuration slices.
Interview Scenario: "A CI/CD tool uses the Metadata API to deploy new fields from a Git branch into a Sandbox environment, while a code editor uses the Tooling API to fetch debug logs on the fly."
Category 04

Specialized UI & Sub-System APIs

GraphQL API & UI API

Client-side UI engines built to fetch data alongside context layout rules simultaneously.

Use Case:Powering Lightning Web Components (LWC), custom web portals, and performance-optimized mobile layouts.
Benefits:GraphQL avoids over-fetching data by returning exactly the fields requested in a single call. UI API matches user permissions automatically.
Interview Scenario: "A custom LWC component needs to show an Account name, related Contact details, and active user profile layout settings all in one network request to maximize page load speeds."

Connect REST API

Specialized programmatic layer mapping back to cloud features like Chatter feeds, Experience sites, and Commerce features.

Use Case:Building customized social networking layers, B2B commerce shopping experiences, or custom frontends for CMS.
Benefits:Returns responses pre-formatted for human reading (e.g., parses Chatter text links automatically).
Interview Scenario: "An external mobile shopping app wants to showcase active products directly from B2B Commerce Cloud and push localized activity post updates right into the user's account dashboard."

⏱️ Pre-Interview Flash Recap

  1. Use Bulk API 2.0 when data exceeds 50,000 records.
  2. Use Composite API instead of looping standard REST API calls to avoid hitting request rate limits.
  3. Choose GraphQL API for mobile applications to reduce data usage and network payloads.
  4. Remember that Metadata API operates on structural configurations, while the Tooling API runs faster on smaller metadata subsets.

Comments

Post a Comment

Popular posts from this blog

Image
Shoot Your Custom Notifications Via Apex        Summer 19 bought a lot of surprises and one of the most enchanting one was that to send custom bell notifications from our inmate, the "Process Builder".       Custom notifications are the soul of the modern business. This feature allows you to send important information, via push to mobile or desktop alerts.    Notifications can be tailor made to inform users regarding any of the record update.  Custom Bell Notifications provide the flexibility of showcasing relevant information at the right time to our users.        All these involves just a handful of steps.       From setup, enter Custom Notifications in the quick find box.      Create a new custom notifications type, also define either desktop or phone to pop-up your notifications. You can select both the locations.        Hope that wa...
Read more

Communicating between Independent LWC in Omniscript

Image
This is a simple example that shows a button that, when clicked, publishes a message. This shows how two separate custom LWCs can communicate with each other inside of an OmniScript. Below is the overall design using the Pub/Sub model. So, lets get started! Step 1: Create a LWC component and use below code to fire events with parameters to pass an omniscript and component to Community Page. Below is the HTML and JS code for reference. SampleLWCComponent.html < template > < lightning-button label = "Send Event" onclick = {handleClick} ></ lightning-button > </ template > SampleLWCComponent.js import { LightningElement } from 'lwc' ; import pubsub from 'vlocity_ins/pubsub' ; export default class SampleLWCComponent extends LightningElement { handleClick ( e ){ let accId = '0015g00000gWY8VAAW' ; pubsub . fire ( "handlePubSubEventChange" , "result" , { "accId" : ac...
Read more

JWT (JSON Web Token)

Image
Introduction to JSON Web Tokens JSON Web Token (JWT) is an open standard ( RFC 7519 ) that defines a compact and self-contained way for securely transmitting information between parties as a JSON object. This information can be verified and trusted because it is digitally signed. JWTs can be signed using a secret (with the  HMAC   algorithm) or a public/private key pair using  RSA  or  ECDSA . When should you use JSON Web Tokens? Here are some scenarios where JSON Web Tokens are useful: Authorization: This is the most common scenario for using JWT. Once the user is logged in, each subsequent request will include the JWT, allowing the user to access routes, services, and resources that are permitted with that token. Single Sign On is a feature that widely uses JWT nowadays, because of its small overhead and its ability to be easily used across different domains. Information Exchange: JSON Web Tokens are a good way of securely transmitti...
Read more

Efficient way to write apex code

Apex Performance Optimization Set.contains() vs. List.contains() Why minor collection choices dictate transaction scaling and CPU governor limits in Apex. "Guess what? Small programmatic choices matter immensely in multi-tenant environments." If you’re having a cup of tea, pause for a moment. The next two minutes will reveal a simple yet overlooked reality in Salesforce development. Lists and Sets are our absolute go-to collections during a typical development cycle. However, after looking at the mathematical reality behind how the compiler evaluates them, you will definitely double-check your code before deploying. The Benchmark Setup Let’s take two collection variants—a List<Integer> and a Set<Integer> —and load them with 100,000 identical elements. Which data structure yields faster lookup performance when running a .contain...
Read more

Import third party JS library in OmniScript Custom Lightning Web Components

 Import third party JS library in OmniScript Custom Lightning Web Components This post explains how to import third-party libraries in omniscript custom lightning web components(lwc). We can not directly import the third party scripts in Lightning web components because Security purpose. We will get error as  "This page has an error. You might just need to refresh it. Error in $A.getCallback() [Assertion Failed!: Scoped imports not allowed when a runtime namespace is specified" Salesforce restrict the importing scripts from third-party content delivery sites like cdnjs, jsdelivr, etc.  Firstly, you need to download the scripts from third-party sites. Then upload the scripts in static resources. Syntax import { loadScript } from 'lightning/platformResourceLoader' ; import { OmniscriptBaseMixin } from 'vlocity_cmt/omniscriptBaseMixin' ; platformResourceLoader  have two methods  loadStyle , and  loadScript.  For both methods return type is Promise....
Read more

Server-Side Document Generation

Image
Document Generation                  With Document Generation , you can generate contracts, proposals, quotes, reports, non-disclosure agreements, service agreements, and so on. Client-side document generation  requires a user interaction and generates documents using an OmniScript. Salesforce provides sample OmniScripts and Integration Procedures that you can use and customize to implement these capabilities. Server-side document generation   typically doesn’t require user interaction. Instead, a backend server processes requests to generate documents. Let’s examine the differences between client-side and server-side document generation.   Client-Side Document Generation  ...
Read more

Salesforce Best Features available

1. Get Merged Body Without Extra Effort Use the renderStoredEmailTemplate method to get the merged email body automatically without manually replacing merge fields. EmailTemplate emailTemplate = [SELECT Id FROM EmailTemplate WHERE Name = 'Test1' LIMIT 1]; Messaging.SingleEmailMessage email = Messaging.renderStoredEmailTemplate(emailTemplate.Id, UserInfo.getUserId(), AccountObj.Id); System.debug(email.plainTextBody); 2. Business Hour Calculations Example in Apex This snippet checks whether a specific time falls within your organization's default business hours. public static Boolean checkBusinessHour() { // Business hour logic List<BusinessHours> defaultBusinessHours = [SELECT Id FROM BusinessHours WHERE Name = 'Default' AND IsDefault = TRUE AND IsActive = TRUE LIMIT 1]; // Find whether the time is within the default business hours return BusinessHours.i...
Read more

Reusable Code in OmniScript - Lightning Web Components

Lightning Web Components are great for breaking down layouts and interfaces into small, reusable pieces. Step 1: Create Lightning Web Component BaseComponent is via a BaseComponent folder in the standard LWC folder of a SFDX project. Export and Import Inside baseComponent.js, we can define reusable functions and export them for use in other components. In the example below, I define a function called convertToArray and export it BaseComponent import { LightningElement } from 'lwc' ; import { OmniscriptBaseMixin } from 'vlocity_cmt/omniscriptBaseMixin' ; export default class BaseComponent extends OmniscriptBaseMixin ( LightningElement ) { } export function convertToArray ( obj ) { if ( obj instanceof Array ) { return obj ; } else { return [ obj ]; } } Child Component import { LightningElement , api , track } from 'lwc' ; import { OmniscriptBaseMixin } from 'vlocity_cmt/omniscriptBaseMixin' ; ...
Read more

Mastering the Matrix: Top 10 Advanced Salesforce Integration Interview Questions

Mastering the Matrix: Top 10 Advanced Salesforce Integration Interview Questions Designing integrations in Salesforce is straightforward when everything goes right. But true senior developers and architects are defined by how they handle system failures, governance limits, and data integrity when things break down. If you are preparing for a senior-level Salesforce interview or looking to build bulletproof systems, these 10 advanced integration questions from the SF Interview Pro Guide explore the deep architectural decisions that separate the juniors from the experts. 1. Why can't you make HTTP callouts directly from Apex triggers, and how do you resolve it? The Core Problem: Salesforce executes triggers within an active database transaction (DML). While a database transaction remains open, Salesforce prohibits holding a thread open to wait for a response from an external system...
Read more