E.2.3 Remote Call Interface Library Units
A remote call interface library unit can be used
as an interface for remote procedure calls (RPCs) (or remote function
calls) between active partitions.
Syntax
The
form of a
pragma
Remote_Call_Interface is as follows:
pragma Remote_Call_Interface[(
library_unit_name)];
The form of a
pragma
All_Calls_Remote is as follows:
pragma All_Calls_Remote[(
library_unit_name)];
A
pragma
All_Calls_Remote is a library unit pragma.
Legality Rules
A
remote call interface (RCI) is a library unit to which the pragma
Remote_Call_Interface applies. A subprogram declared in the visible part
of such a library unit, or declared by such a library unit, is called
a
remote subprogram.
The declaration of an RCI library unit shall be preelaborable
(see
10.2.1), and shall depend semantically
only upon declared pure, shared passive, remote types, or other remote
call interface library units.
In addition, the following
restrictions apply to an RCI library unit:
its visible part shall not contain the declaration
of a variable;
its visible part shall not contain the declaration
of a limited type;
it shall not be, nor shall its visible part contain,
the declaration of a subprogram to which a pragma Inline applies;
it shall not be, nor shall its visible part contain,
a subprogram (or access-to-subprogram) declaration whose profile has
an access parameter or a parameter of a type that does not support external
streaming (see
13.13.2);
any public child of the library unit shall be a
remote call interface library unit.
If a pragma All_Calls_Remote applies to a library
unit, the library unit shall be a remote call interface.
Post-Compilation Rules
A remote call interface library unit shall be assigned
to at most one partition of a given program. A remote call interface
library unit whose parent is also an RCI library unit shall be assigned
only to the same partition as its parent.
Notwithstanding
the rule given in
10.2, a compilation unit
in a given partition that semantically depends on the declaration of
an RCI library unit,
needs (in the sense of
10.2)
only the declaration of the RCI library unit, not the body, to be included
in that same partition. Therefore, the body of an RCI library unit is
included only in the partition to which the RCI library unit is explicitly
assigned.
Implementation Requirements
If a pragma All_Calls_Remote applies to a given RCI
library unit, then the implementation shall route any call to a subprogram
of the RCI unit from outside the declarative region of the unit through
the Partition Communication Subsystem (PCS); see
E.5.
Calls to such subprograms from within the declarative region of the unit
are defined to be local and shall not go through the PCS.
Implementation Permissions
An implementation need not support the Remote_Call_Interface
pragma nor the All_Calls_Remote pragma. Explicit message-based communication
between active partitions can be supported as an alternative to RPC.
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