MRCP response messages

An MRCP response message consists of a Response line followed by the message header section and an optional message body containing data specific to the method.

response-line      = mrcp-version SP message-length SP request-id 
                             SP status-code SP request-state CRLF

The mrcp-version field specifies the MRCP protocol version that is being used by the client:

mrcp-version       = "MRCP" "/" 1*DIGIT "." 1*DIGIT

MRCP Versions supported by the LumenVox Media Server are: MRCP/1.0 and MRCP/2.0

The message-length field describes the length of the message (in bytes), including the start-line:

message-length     = 1*19DIGIT

The request-id field is a unique identifier associated with each request. Clients should assign incremental numbers to each unique request, and the Media Server will use this request-id when responding to requests. In the response message, this value indicates which specific request the response relates to.

request-id         = 1*10DIGIT

The status-code field is a 3-digit code representing the success or failure or other status of the request.

status-code        =    3DIGIT

The request-state field indicates if the action initiated by the request is PENDING, IN-PROGRESS or COMPLETE.  The COMPLETE status means that the Request was processed to completion and that there will be no more events or other messages from that resource to the client with that request-id.  The PENDING status means that the request has been placed on a queue and will be processed in first-in-first-out order.  The IN-PROGRESS status means that the request is being processed and is not yet complete.  A PENDING or IN-PROGRESS status indicates that further Event messages may be delivered with that request-id.

request-state      =  "COMPLETE" 
              /  "IN-PROGRESS" 
              /  "PENDING"


Status Codes

The status codes are classified under the Success (2XX) codes, Client Failure (4XX) codes, and Server Failure (5XX).


Success Codes

Code

Meaning

200

Success

201

Success with some optional header fields ignored

Client Failure 4xx Codes

Code

Meaning

401

Method not allowed

402

Method not valid in this state

403

Unsupported header field

404

Illegal value for header field.  This is the error for a syntax violation.

405

Resource not allocated for this session or does not exist

406

Mandatory Header Field Missing

407

Method or Operation Failed (e.g., Grammar compilation failed in the recognizer.  Detailed cause codes might be available through a resource specific header.)

408

Unrecognized or unsupported message entity

409

Unsupported Header Field Value.  This is a value that is syntactically legal but exceeds the implementation's capabilities or expectations.

410

Non-Monotonic or Out of order sequence number in request.

411-420

Reserved for future assignment

Server Failure 5xx Codes

Code

Meaning

501

Server Internal Error

502

Protocol Version not supported

503

Reserved for future assignment

504

Message too large



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