An API (Application Programming Interface) endpoint is the standard, most effective method for integrating two distinct SaaS-based applications. APIs provide a structured, programmatic way for services to communicate, exchange data, and trigger actions in each other. In this scenario, the detecting tool would make a call to the receiving tool's API endpoint, sending structured data about the threat (e.g., in JSON format). This allows for reliable, real-time, and automated communication, which is fundamental for modern security orchestration and response workflows. This method is far more robust and scalable than alternative notification systems like email or file sharing.

A. SMB share: This is a network file-sharing protocol. Using it for application integration is inefficient, insecure, and not designed for real-time, event-driven communication between SaaS platforms.
C. SMTP notification: This uses email for alerts. While functional for human notification, it is a poor method for machine-to-machine integration as it requires parsing unstructured data and lacks reliability.
D. SNMP trap: This is a protocol for monitoring network devices and infrastructure components. It is not designed for the complex, high-level data exchange required between SaaS security applications.

1. Vendor Documentation: Palo Alto Networks. (2023). Cortex XSOAR Administrator's Guide. In the "Integrations" section

the guide details how the platform "interacts with third-party applications... through APIs" to orchestrate security actions

demonstrating this as the industry-standard practice for tool integration.

2. Academic Publication: Tounsi

W.

& Frikha

M. (2018). A survey on security orchestration

automation and response (SOAR). 2018 International Conference on Smart Communications in Network Technologies (SaCoNeT)

(pp. 1-6). The paper explicitly states that SOAR platforms "rely on APIs and connectors to integrate with a wide range of security tools" (Section III.A

"Integration and Interoperability"). This highlights the critical role of APIs in connecting security tools. https://doi.org/10.1109/SaCoNeT.2018.8585556

3. University Courseware: Saltzer

J. H.

& Kaashoek

M. F. (2018). 6.033 Computer System Engineering

Lecture 20: Distributed Systems Part 3: Remote Procedure Call. MIT OpenCourseWare. This lecture covers the foundational principles of Remote Procedure Calls (RPCs)

the conceptual predecessor to modern web APIs

explaining how they are designed to allow different programs on different machines to communicate as if they were local

which is the core goal of the integration described in the question.