Package io.grpc

Class Metadata.Key<T>

  • Enclosing class:

    public abstract static class Metadata.Key<T>
    extends Object
    Key for metadata entries. Allows for parsing and serialization of metadata.

    Valid characters in key names

    Only the following ASCII characters are allowed in the names of keys:

    • digits: 0-9
    • uppercase letters: A-Z (normalized to lower)
    • lowercase letters: a-z
    • special characters: -_.

    This is a strict subset of the HTTP field-name rules. Applications may not send or receive metadata with invalid key names. However, the gRPC library may preserve any metadata received even if it does not conform to the above limitations. Additionally, if metadata contains non conforming field names, they will still be sent. In this way, unknown metadata fields are parsed, serialized and preserved, but never interpreted. They are similar to protobuf unknown fields.

    Note this has to be the subset of valid HTTP/2 token characters as defined in RFC7230 Section 3.2.6 and RFC5234 Section B.1

    Note that a key is immutable but it may not be deeply immutable, because the key depends on its marshaller, and the marshaller can be mutable though not recommended.

    See Also:
    Wire Spec, RFC7230, RFC5234