Supported Connection Protocols

Capacity Private Cloud supports multiple connection protocols to integrate with your applications. Choose the protocol that best fits your architecture and use case.

gRPC

gRPC is a cross-platform, open-source, high-performance Remote Procedure Call (RPC) framework initially created by Google. This is the preferred protocol for communicating with the platform, offering built-in support for load balancing, tracing, health checking, and authentication. gRPC is optimized for scalability in cloud and microservices environments.

All major programming languages can access the API via gRPC. See the gRPC supported languages documentation for details.

For protocol specifications, refer to the Protocol Documentation.

MRCP

Media Resource Control Protocol (MRCP) is a communication protocol between voice IVR platforms and the ASR and TTS resources serving them. MRCP uses specific methods to control speech resources, such as starting and stopping recognizers or managing speech synthesizers.

Two versions of MRCP are supported:

  • MRCPv1 — Uses RTSP (Real Time Streaming Protocol) for combined session management and content delivery. See RFC 4463.
  • MRCPv2 — Uses SIP (Session Initiation Protocol), enabling separate session management and allowing ASR and TTS to operate concurrently within a single session. See RFC 6787.

Deployment Note: MRCP services run on dedicated virtual machines using Docker, as MRCP uses UDP and TCP ports not currently supported by Kubernetes. A media server positioned outside the cluster facilitates communication between MRCP clients and the platform API via gRPC. For detailed architecture and setup information, see Media Server Connectivity.

MRCP services are deployment-specific—there is no option to change the deployment ID used by the service.

REST

REST over HTTP is a traditional model for communication with backend servers, following stateless request-response patterns. REST APIs are used for:

  • Voice Biometric APIs
  • Voice Biometric Reporting APIs
  • Management APIs

While REST is widely supported, traditional stateless HTTP does not work well for applications requiring real-time data streaming. For real-time speech processing, consider gRPC or MRCP.

For REST API specifications, refer to the Management API Documentation.

Was this article helpful?