| # Sequence Number # |
| |
| Apache Thrift built sequence numbers into every protocol exchange to allow |
| for clients that may submit multiple outstanding requests on a single transport |
| connection. This is typically done by asynchronous clients. |
| |
| The following rules apply to sequence numbers: |
| |
| 1. A sequence number is a signed 32-bit integer. Negative values are allowed. |
| 1. Sequence numbers `MUST` be unique across all outstanding requests on a |
| given transport connection. There is no requirement for unique numbers |
| between different transport connections even if they are from the same client. |
| 1. A server `MUST` reply to a client with the same sequence number that was |
| used in the request. This includes any exception-based reply. |
| 1. A client `MAY` use sequence numbers if it needs them for proper operation. |
| 1. A client `SHOULD` set the sequence number to zero if it does not rely |
| on them. |
| 1. Wrapped protocols (such as THeaderProtocol) `SHOULD` use the same sequence |
| number on the wrapping as is used on the payload protocol. |
| |
| Servers will not inspect or make any logic choices based on the sequence number |
| sent by the client. The server's only job is to process the request and reply |
| with the same sequence number. |
