1Glossary 2================ 3 4.. glossary:: 5 6 metadatum 7 A key-value pair included in the HTTP header. It is a 8 2-tuple where the first entry is the key and the 9 second is the value, i.e. (key, value). The metadata key is an ASCII str, 10 and must be a valid HTTP header name. The metadata value can be 11 either a valid HTTP ASCII str, or bytes. If bytes are provided, 12 the key must end with '-bin', i.e. 13 ``('binary-metadata-bin', b'\\x00\\xFF')`` 14 15 metadata 16 A sequence of metadatum. 17 18 serializer 19 A callable function that encodes an object into bytes. Applications are 20 allowed to provide any customized serializer, so there isn't a restriction 21 for the input object (i.e. even ``None``). On the server-side, the 22 serializer is invoked with server handler's return value; on the 23 client-side, the serializer is invoked with outbound message objects. 24 25 deserializer 26 A callable function that decodes bytes into an object. Same as serializer, 27 the returned object doesn't have restrictions (i.e. ``None`` allowed). The 28 deserializer is invoked with inbound message bytes on both the server side 29 and the client-side. 30 31 wait_for_ready 32 If an RPC is issued but the channel is in the TRANSIENT_FAILURE or SHUTDOWN 33 states, the library cannot transmit the RPC at the moment. By default, the 34 gRPC library will fail such RPCs immediately. This is known as "fail fast." 35 RPCs will not fail as a result of the channel being in other states 36 (CONNECTING, READY, or IDLE). 37 38 When the wait_for_ready option is specified, the library will queue RPCs 39 until the channel is READY. Any submitted RPCs may still fail before the 40 READY state is reached for other reasons, e.g., the client channel has been 41 shut down or the RPC's deadline has been reached. 42 43 channel_arguments 44 A list of key-value pairs to configure the underlying gRPC Core channel or 45 server object. Channel arguments are meant for advanced usages and contain 46 experimental API (some may not labeled as experimental). Full list of 47 available channel arguments and documentation can be found under the 48 "grpc_arg_keys" section of "channel_arg_names.h" header file 49 (|channel_arg_names_link|). For example, if you want to disable TCP port 50 reuse, you may construct channel arguments like: 51 ``options = (('grpc.so_reuseport', 0),)``. 52