How can developers expose custom business functionality from Dynamics 365 Finance and Operations to external applications?

Enterprise applications frequently need to exchange business data and functionality with external systems such as portals, mobile applications, CRM platforms, and integration services. This discussion explores how Dynamics 365 Finance and Operations developers can expose business functionality using approaches such as OData, custom services, REST-based integrations, business events, and Azure integration patterns. The focus is on choosing the appropriate integration approach based on security, scalability, transaction requirements, and business needs. This provides valuable architectural insight for X++ developers and Dynamics 365 technical consultants.