API Gateway Components

API Gateway consists of the following components:

The following table lists the purpose and characteristics of the API Gateway components.

Component	Purpose	Characteristics
Integration Server	Policy Enforcement Engine	Stateless engine Two or more instances can operate as a cluster Supports vertical and horizontal scaling It runs an embedded Apache Tomcat server to host API Gateway console UI
Elasticsearch	Persistence layer for API configurations and API analytics	Stateful persistence Externalized Elasticsearch is supported Needs quorum (odd number of instances) to operate in a cluster Note: Best practice is to separate the API analytics in a dedicated cluster. Supports horizontal scaling and data- sharing
Kibana	Dashboard for the API analytics	Stateless engine Externalized Kibana is supported Two instances can operate in a cluster Scaling more than two is generally not required
Cluster Coordinator	In-Memory Distributed Caching	Stateful engine for cluster coordination and service result caching Two options: Ignite Terracotta Server Array (TSA) Ignite is embedded and scales as you scale the Integration Server. TSA operates in an active-passive setup, typically, two instances are sufficient. Scaling more than two is not required and an anti-pattern .

Note: All the components can run in containers.

For more information on the supported versions of external Elasticsearch, Kibana, and Terracotta Server Array, see API Gateway, Elasticsearch, Kibana, and TSA Compatibility Matrix.