However, developing these applications is far from trivial because of the engineering challenges—ranging from subscribing to various data sources, and defining complex streaming transformations, to integrating with multiple data sinks. 

Key takeaways:

• How declarative interfaces simplify the development of streaming applications at Airbnb
• Benefits of GraphQL in designing the declarative interface for streaming applications
• How to reuse data sources and common logic across different streaming applications
• Best practices and lessons learned in developing streaming applications based on the declarative interface at Airbnb