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.
Ada 2005 and 2012 Editions sponsored in part by Ada-Europe
