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| author |  Abhishek Kumar <abhikumar@google.com> | 2015-01-22 10:13:34 -0800 |
|---|---|---|
| committer | Abhishek Kumar <abhikumar@google.com> | 2015-01-22 10:13:34 -0800 |
| commit | bb20de4c3f0a03d4206d3fb1434c67b0ea514398 (patch) | |
| tree | 9917cdca1171d9f0031bf021f24ac810525238da /README.md | |
| parent | 0adce9db94793fc25603334268ce771e174fa673 (diff) | |
Update README.md
Diffstat (limited to 'README.md')
| -rw-r--r-- | README.md | 9 |
1 files changed, 5 insertions, 4 deletions
@@ -57,9 +57,6 @@ the client and the server can send a stream of messages to each other. The strea messages are delivered in the order they were sent. - - - #Protocol The gRPC protocol specifies the abstract requirements for communication between @@ -67,6 +64,10 @@ clients and servers. A concrete embedding over HTTP/2 completes the picture by fleshing out the details of each of the required operations. ## Abstract gRPC protocol -A gRPC RPC comprises of a bidirectional stream of messages, initiated by the client. In the client-to-server direction, this stream begins with a mandatory 'Call Header', followed by optional `Initial-Metadata`, followed by zero or more `Payload Messages`. The server-to-client direction contains an optional `Initial-Metadata`, followed by zero or more `Payload Messages` terminated with a mandatory `Status` and optional `Status-Metadata` (a.k.a.,`Trailing-Metadata'). +A gRPC RPC comprises of a bidirectional stream of messages, initiated by the client. In the client-to-server direction, this stream begins with a mandatory `Call Header`, followed by optional `Initial-Metadata`, followed by zero or more `Payload Messages`. The server-to-client direction contains an optional `Initial-Metadata`, followed by zero or more `Payload Messages` terminated with a mandatory `Status` and optional `Status-Metadata` (a.k.a.,`Trailing-Metadata`). + +## Implementation over HTTP/2 +The abstract protocol defined above is implemented over [HTTP/2](https://http2.github.io/). gRPC bidirectional streams are mapped to HTTP/2 streams. The contents of `Call Header` and `Initial Metadata` are sent as HTTP/2 headers and subject to HPAC compression. `Payload Messages` are serialized into a byte stream of length prefixed gRPC frames which are then fragmented into HTTP/2 frames at the sender and reassembled at the receiver. `Status` and `Trailing-Metadata` are sent as HTTP/2 trailing headers (a.k.a., trailers). +**TODO(a11r): Add a section on flow control.** |