get_message_tuple — Retrieve a tuple associated with the key from the message.
get_message_tuple retrives a tuple associated with the Key from the message denoted by the MessageHandle. The tuple has to be previously stored to the message using set_message_tuple.
The operator returns the data in the parameter TupleData. The data including strings is copied by the operation, the message can thus be immediately reused.
If the given Key is not present in the message or if the data associated with the key is not a tuple, get_message_tuple fails. Presence of keys and information about the data associated with the key can be verified using get_message_param.
Number of elements: MessageHandle == 1
Restriction: MessageHandle != 0
Number of elements: Key == 1
Restriction: length(Key) > 0
Tuple value retrieved from the message.
* ... get_message_param (Message,'key_exists',['simple_string','foo','my_image'],\ KeysPresence) get_message_param (Message,'key_data_type',['simple_string','my_image'],\ KeysType) get_message_tuple (Message,'simple_string',TupleString)
If the operation succeeds, get_message_tuple returns 2 (H_MSG_TRUE). Otherwise an exception is raised. Possible error conditions include invalid parameters (handle or key), the required key not found in the message, or other than tuple data associated with given key.
create_message, clear_message, set_message_tuple, set_message_obj, get_message_obj, set_message_param, get_message_param, enqueue_message, dequeue_message