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PerStreamDataMimeTypesDefinition.md

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Stream Data MIME Types Metadata Extension

This extension specification is currently incubating. While incubating the version is 0.

Introduction

The definition of the Payload data MIME type is an integral part of the RSocket and Extension specifications. However, due to its definition as per connection, it is non-trivial to make it suitable for cases where streams within a single connection need to use different MIME types. Therefore, this extension specification provides an interoperable structure for metadata payloads to declare MIME type information. It is designed such that Requester can use CompositeMetadata to declare the request Payload data MIME type and a set of expected, acceptable response Payload(s) data MIME types. If data MIME type is not declared, then the MIME type declared in the ConnectionSetupPayload MUST be used instead. As per definition, the declaration of acceptable data MIME types is made by the Requester and may be considered by the Responder for encoding response data. If the response Payload(s) data MIME type is other than specified by the Requester, then the Responder MUST specify the response data MIME type in the Metadata Payload using CompositeMetadata. Declaration of the acceptable data MIME types by the Responder MUST be considered invalid and ignored by the Requester.

Metadata Payload for data MIME Type

This metadata type is intended to be used per stream, and not per connection nor individual payloads and as such it MUST only be used in frame types used to initiate interactions. This includes REQUEST_FNF, REQUEST_RESPONSE, REQUEST_STREAM, and REQUEST_CHANNEL. Multiple metadata payloads with the same MIME type are allowed. The order of metadata payloads MUST be preserved when presented to responders. The Metadata MIME Type is message/x.rsocket.mime-type.v0.

Metadata Contents

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |M| MIME ID/Len |   Data Encoding MIME Type                    ...
    +---------------+-----------------------------------------------+
  • (M)etadata Type: Metadata type is a well known value represented by a unique integer.
  • MIME ID/Length: (7 bits = max value 2^7 = 128) Unsigned 7-bit integer. If M flag is set, indicates a Well-known MIME Type ID. If M flag is not set, indicates the encoding MIME Type Length in bytes.
  • Metadata Encoding MIME Type: MIME Type for encoding of Metadata. This SHOULD be a US-ASCII string that includes the Internet media type specified in RFC 2045. Many are registered with IANA and others such as Routing and Tracing (Zipkin) are not. Suffix rules MAY be used for handling layout. The string MUST NOT be null terminated. (Not present if M flag is set)

Metadata Payload for acceptable data MIME Types

This metadata type is intended to be used per stream, and not per connection nor individual payloads and as such it MUST only be used in frame types used to initiate interactions. This includes REQUEST_FNF, REQUEST_RESPONSE, REQUEST_STREAM, and REQUEST_CHANNEL. Multiple metadata payloads with the same MIME type are allowed. The order of metadata payloads MUST be preserved when presented to responders. The Metadata MIME Type is message/x.rsocket.accept-mime-types.v0.

Metadata Contents

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |M| MIME ID/Len |   Data Encoding MIME Type                    ...
    +---------------+-----------------------------------------------+
    |M| MIME ID/Len |   Data Encoding MIME Type                    ...
    +---------------+-----------------------------------------------+
                                   ...
  • (M)etadata Type: Metadata type is a well known value represented by a unique integer.
  • MIME ID/Length: (7 bits = max value 2^7 = 128) Unsigned 7-bit integer. If M flag is set, indicates a Well-known MIME Type ID. If M flag is not set, indicates the encoding MIME Type Length in bytes.
  • Metadata Encoding MIME Type: MIME Type for encoding of Metadata. This SHOULD be a US-ASCII string that includes the Internet media type specified in RFC 2045. Many are registered with IANA and others such as Routing and Tracing (Zipkin) are not. Suffix rules MAY be used for handling layout. The string MUST NOT be null terminated. (Not present if M flag is set)