OSI/MHS Gateway Programmatic Interface (GPI) Programming Guide

GPI Object Management
OSI/MHS Gateway Programmatic Interface (GPI) Programming Guide—424822-001
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How Objects Work
How Objects Work
The purpose of objects is to shield the client from the complexity of native X.400
format. The client does not operate on “raw” X.400 messages: it operates on objects
that represent X.400 messages. Objects contain the same information but are easier to
use.
It’s important to realize that objects and attributes are abstract structures. They were
invented by the XAPIA to help define the procedural interface. Objects and attributes
are not data structures, nor do they represent the physical organization of data in
memory.
The following subsections further explain objects and show how root objects are used to
represent messages, probes, reports, and P1-encoded objects.
Properties of Objects
The nature of objects is fairly straightforward:
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Objects are built from attributes.
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Objects can contain other objects.
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Objects are grouped into classes.
Objects Are Built From Attributes
An object is simply a collection of attributes (Figure 3-1). Each attribute represents a
separate information item. Because objects are collections of attributes, it follows that
objects represent collections of information items.
Attributes are inserted or removed to compose or decompose an object. If an object has
no attributes, it consists only of the object identifier which labels it. The object
identifier is used when calling procedures that operate on the object or its parts.
GPI_OM_READ_ Reads a segment of a data string from a value of an attribute
GPI_OM_REMOVE_ Removes and discards attribute values of an object
GPI_OM_WRITE_ Writes a segment of a data string to a value of an attribute
Table 3-1. GPI Object Management Procedures (page 2 of 2)
Procedure Name Purpose