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SEMI E42-0704 © SEMI 1995, 2004 32 Figure 5.1 illustrates a distributed recipe names pace with four segments , each provide d by a different agent , and each agent als o having a local names pace . Figure 5.1 Illustratio…

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Table 4.1 Recipe Namespace Attribute Definition

Attribute Name Definition Access Rqmt Form

ObjType The object type. RO Y Text = "RNS"

ObjID The name of the namespace. RO Y Text. A name of "Default" is

prohibited.

RecipeReadOnly-

Level

The level of approval at which recipes are read-only. RW Y Unsigned integer.

Members The names of agents capable of verifying and executing

the recipes in the namespace.

RW Y List of agent names

(identifiers).

SynchOn Level of synchronization (see Section 9.5). Required if

synchronization is supported.

RW N Unsigned integer:

Either 0 = Disabled, or any

combination (sum) of:

1 = changes in body

2 = new execution recipe

8 = changes in last value

16 = new derived object

form execution recipe

SynchFail Specifiers for execution recipes for which an attempt to

synchronize failed. Required if synchronization is

supported.

RW N List of formatted text.

Table 4.2 defines the attributes of the recipe namespace manager objects. The name (identifier) of the manager is

not generally of interest, as the namespace specifier is more commonly used. However, it is important for the

manager to be accessible through Object Services.

Table 4.2 Recipe Namespace Manager Attribute Definition

Attribute Name Definition Access Rqmt Form

ObjType The object type. RO Y Text = "RNS_Mgr"

ObjID The manager's name. RO Y Text.

NamespaceName The name of the namespace managed. RO Y Text.

5 Distributed Recipe Namespace

A distributed recipe namespace is a recipe namespace that utilizes the storage capacity of multiple agents for

recipe storage. Recipes are stored in special recipe namespace segments provided by the different agents. These

segments are distributed recipe namespace segments and are supervised by the distributed recipe namespace

manager.

This section defines the different objects that together provide the distributed recipe namespace capability: the

distributed recipe namespace, the distributed recipe namespace manager, the distributed recipe namespace

segment, and the distributed recipe namespace recorder. Detailed descriptions of operations are contained in

Section 10.

Throughout this document, the acronym DRNS refers to the term "distributed recipe namespace" and is used

primarily to differentiate a DRNS subtype object from its supertype.

5.1 Motivations — The distributed recipe namespace capability provides a method for using the storage capacity of

multiple agents, as illustrated in Figure 5.1. This reduces the storage requirements of a centralized factory system,

improves performance by allowing recipes to be used by those agents, and provides a centralized management of the

namespace to ensure that the uniqueness of the recipe identifier is properly maintained.

SEMI E42-0704 © SEMI 1995, 2004 32

Figure 5.1 illustrates a distributed recipe namespace with four segments, each provided by a different agent, and

each agent also having a local namespace.

Figure 5.1

Illustration of Agents, Segments, and Local Namespaces

5.2 Overview — The DRNS object model (Figure 5.2) is a specialization of the model introduced in Section 4. The

distributed recipe namespace, the DRNS segment, and the DRNS manager are subtypes of the recipe namespace, the

recipe namespace segment, and the recipe namespace manager respectively. Each inherits the attributes and

operations of its corresponding supertype. Only those attributes and operations that are specific to the DRNS types

are shown in object representations.

Figure 5.2

Distributed Recipe Namespace Model

The namespace supertype has exactly one segment of storage. Where storage is centralized, the segment is internal

and private to the namespace. However, in the case of the distributed recipe namespace, there may be multiple

DRNS segments, each provided by a separate agent. For this reason, the DRNS segment is a standardized object.

The distributed recipe namespace separates the management of recipes within a specific recipe storage area from the

management of the entire namespace. The management of individual recipes within a specific storage area is

delegated to the distributed recipe namespace segment. The distributed recipe namespace manager manages the

various segments and the namespace itself. The manager is responsible for knowing the identifiers of all recipes

stored in the entire namespace. It requires a knowledge of the structure of the recipe's identifier and the significance

of the version in differentiating between recipes of the same name and different versions.

The DRNS recorder provides a backup facility for information required to automate the rebuilding of a distributed

recipe namespace. It is external to the DRNS namespace and to its DRNS manager.