This episode outlines the essential requirements for Salesforce to securely communicate with external systems through API callouts. It highlights the critical need for authorisation, which verifies Salesforce's permission to access external data, typically through methods like API keys or the more secure OAuth 2.0. The episode also stresses the importance of specifying the correct API endpoint details, acting as the precise address for the external service, and selecting the appropriate request method (HTTP Verb), such as GET for retrieving or POST for creating data, to define the intended action. Furthermore, it covers the inclusion of a request body for sending data, the necessity of understanding the expected response from the external system for proper data handling and error management, and finally, the Salesforce-specific security configuration of Remote Site Settings or Named Credentials to permit outbound connections.

An Application Programming Interface (API) acts as a digital messenger, enabling different software applications to communicate and share data. The fundamental principle of API interaction is that the system offering a service must provide the API, which the calling system then uses to make requests. For instance, in an inbound integration where data enters Salesforce, Salesforce provides the API because it is offering the service of data storage. Conversely, in an outbound integration where Salesforce sends data to another system, the external system provides the API, as it is the one offering the service to receive and process that data.

This episode explains Web Services Description Language (WSDL) within the context of Salesforce's SOAP API, detailing its function as an instruction manual for web service communication. It highlights the existence of two distinct types of WSDL offered by Salesforce: Enterprise WSDL and Partner WSDL.