Errors

A failed operation raises ucall.Error, a RuntimeError whose status is the ucall.Status it reported and whose message is a static detail beside it. Each failing status raises a subclass of its own, named after the status, such as ucall.ConnectionFailedError or ucall.NotFoundError. Where a built-in exception names the same fault, the subclass derives it too: ConnectionError for connection failures, TimeoutError, MemoryError, OSError, ValueError for invalid or malformed input, KeyError, NotImplementedError, OverflowError and BlockingIOError. str(error) joins the two, as in “CONNECTION_FAILED: connection-failed”. Arguments of the wrong type raise TypeError, a key of the wrong length or an unknown enum name raises ValueError, and a reply while views over the body are alive raises BufferError.

import ucall

client = ucall.Client(connections=1)
try:
    response = client.get("http://127.0.0.1:1/")
    print("answered", response.status_code)
except ucall.ConnectionFailedError as error:  # or: except ConnectionError
    assert error.status == ucall.Status.CONNECTION_FAILED
    print("nobody listens:", error)

ucall.Status, Backend, CPUClass, Security, Verb, BodyDelivery and LogLevel are enum.IntEnum classes, and every argument taking one also takes its name in any case, with ”-” or ”_” between words. ucall.Status.from_name("out-of-memory") reads a status back from the spelling the library gives it, ucall.version() numbers the linked library, and ucall.__version__ spells it with any candidate suffix. A submitted call that fails completes with that status in Completed.status, such as CONNECTION_FAILED, CONNECTION_CLOSED, TIMEOUT, HANDSHAKE_FAILED or PEER_REJECTED, and HTTP error statuses are ordinary responses. On the serving side, failures become replies rather than exceptions: 400 for parameters that do not bind, 500 for a handler that raised or a request released unanswered.