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E.2.3 Remote Call Interface Library Units

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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

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The form of a pragma Remote_Call_Interface is as follows: 
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  pragma Remote_Call_Interface[(library_unit_name)];
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The form of a pragma All_Calls_Remote is as follows: 
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  pragma All_Calls_Remote[(library_unit_name)];
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A pragma All_Calls_Remote is a library unit pragma. 

Legality Rules

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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.
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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.
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In addition, the following restrictions apply to an RCI library unit: 
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If a pragma All_Calls_Remote applies to a library unit, the library unit shall be a remote call interface. 

Post-Compilation Rules

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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. 
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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

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 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

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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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