2.1.1.2.2.1 Receivers
The receiver MUST include the HTTP header "Supported: com.microsoft.wmdrm-nd" in the HTTP request message to indicate to the transmitter that it supports WMDRM: Network Devices Protocol.
The receiver MUST begin the license retrieval procedure by sending a POST request to the Uniform Resource Locator (URL) that the receiver intends to play. The entity-body of the POST request MUST contain a license request message.
The POST request MUST include a "Content-Type: application/vnd.ms-wmdrm-license-request" header to indicate that the body of the POST request contains a license request message.
Unlike the registration request and registration response messages, the license request and license response messages MUST NOT be Base64 encoded or decoded [RFC3548].
When the receiver receives the response to the POST request, it MUST verify that the response indicates that the request succeeded, and that the response includes the "Content-Type: application/vnd.ms-wmdrm-license-response" header. This header indicates that the entity-body of the response contains a license response message.
If the "WMDRM-ND" HTTP header is present in the response to the POST request, the receiver MUST remember the value of the SessionId parameter in that header. The syntax of the "WMDRM-ND" header is specified in section 2.2. The value of the SessionId parameter MUST be sent back by the receiver when requesting data during the data transfer procedure (defined in section 2.1.1.2.5).
The value of the SessionId parameter used in the "WMDRM-ND" HTTP header is NOT related to the Session ID parameter used in the registration or proximity detection procedures.