Which method is used to achieve real time integration when Salesforce is the integration source?

Salesforce Outbound Messaging is the correct method to achieve real-time integration when Salesforce is the source. This method allows Salesforce to automatically send a message to an external endpoint when a specific event occurs, such as when a record is created or updated. Outbound Messaging operates using the Salesforce platform's native capabilities, leveraging its built-in support for sending SOAP messages to an external service, which can then process the data in real time without needing any polling or scheduling.

This mechanism is particularly beneficial because it works seamlessly within the Salesforce ecosystem, ensuring timely notifications of changes in data without the overhead of additional configuration or third-party solutions. It is designed to be efficient and reliable, providing a way to connect Salesforce with external applications or services in a manner that closely resembles real-time interaction.

The other options, while relevant in different contexts, do not provide the same level of immediacy or integration capability. For example, Salesforce Trigger can automate actions within Salesforce but does not natively communicate with external systems. A Third Party Scheduler schedules operations but is not real-time, and Salesforce API Calls may involve polling or latency, depending on the implementation. Thus, Outbound Messaging stands out as the preferred method for real-time integration from Salesforce.