Ada Reference Manual (Ada 2022)
E.4.1 Asynchronous Remote Calls
This subclause introduces the aspect Asynchronous which can be specified to allow a remote subprogram call to return prior to completion of the execution of the corresponding remote subprogram body.
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Static Semantics
For a remote procedure, the following language-defined representation aspect may be specified:
Asynchronous
The type of aspect Asynchronous is Boolean. If directly specified, the aspect_definition shall be a static expression. If not specified, the aspect is False.
For a remote access type, the following language-defined representation aspect may be specified:
Asynchronous
The type of aspect Asynchronous is Boolean. If directly specified, the aspect_definition shall be a static expression. If not specified (including by inheritance), the aspect is False.
Legality Rules
If aspect Asynchronous is specified for a remote procedure, the formal parameters of the procedure shall all be of mode in.
If aspect Asynchronous is specified for a remote access type, the type shall be a remote access-to-class-wide type, or the type shall be a remote access-to-procedure type with the formal parameters of the designated profile of the type all of mode in.
Dynamic Semantics
A remote call is asynchronous if it is a call to a procedure, or a call through a value of an access-to-procedure type, for which aspect Asynchronous is True. In addition, if aspect Asynchronous is True for a remote access-to-class-wide type, then a dispatching call on a procedure with a controlling operand designated by a value of the type is asynchronous if the formal parameters of the procedure are all of mode in.
Implementation Requirements
Asynchronous remote procedure calls shall be implemented such that the corresponding body executes at most once as a result of the call.
