IEC 61970-405:2007

IEC 61970-405
Edition 1.0 2007-08
INTERNATIONAL
STANDARD
Energy management system application program interface (EMS-API) –
Part 405: Generic Eventing and Subscription (GES)

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IEC 61970-405
Edition 1.0 2007-08
INTERNATIONAL
STANDARD
Energy management system application program interface (EMS-API) –
Part 405: Generic Eventing and Subscription (GES)

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
U
ICS 33.200 ISBN 2-8318-9252-X
– 2 – 61970-405 © IEC:2007(E)
CONTENTS
FOREWORD.4

INTRODUCTION.6

1 Scope.7

2 Normative references .8

3 Terms and definitions .8

4 Generic Eventing and Subscription (Normative).8

4.1 Overview .8
4.1.1 General .8
4.1.2 Suitability of the GES to the integration of a variety of application
categories .9
4.1.3 Suitability of the GES to the integration beyond the control center.9
4.1.4 Suitability of the GES to the integration of tightly coupled and loosely
coupled applications (informative) .10
4.2 Using GES A&E Simple Eventing for Generic Messaging .12
4.2.1 General .12
4.2.2 GES messages.12
4.2.3 Eventing and Subscription topic trees (informative) .13
4.2.4 Subscription filtering.13
4.2.5 GES Publish/Subscribe wildcards .13
4.2.6 Browsing IECTC57 namespaces with GES .14
5 Generic Event Subscription Alarms and Events .16
5.1 Background (informative) .16
5.2 SCADA use case (informative) .16
5.3 Data model (normative) .17
5.4 Messages (normative) .19
5.5 Interface (normative) .21
5.5.1 Objects and interfaces.21
5.5.2 Server and Session interfaces .24
5.5.3 Browse interfaces.24
5.5.4 Client interfaces .26
5.5.5 Mapping DAIS A&E to IEC 61970-3XX series .26

Annex A (informative) Proxy Event Subscription sequence .27

Bibliography.30

Figure 1 – Data subscription .9
Figure 2 – Component architecture .11
Figure 3 – Populated namespace example for IECTC57PhysicalModel (informative).14
Figure 4 – Typical SCADA flows of DAIS alarms and events .16
Figure 5 – GES A&E data model .18
Figure 6 – Event messages.20
Figure 7 – GES A&E objects and interfaces .22
Figure 8 – Typical interaction between the DAIS A&E objects .24

61970-405 © IEC:2007(E) – 3 –
Figure A.1 – Proxy subscription and callback sequence with multiple servers .27

Figure A.2 – Proxy subscription sequence with multiple clients .28

Figure A.3 – Proxy callback sequence with multiple servers.28

Figure A.4 – Proxy callback sequence with multiple clients .29

– 4 – 61970-405 © IEC:2007(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION

______________
ENERGY MANAGEMENT SYSTEM
APPLICATION PROGRAM INTERFACE (EMS-API) –

Part 405: Generic Eventing and Subscription (GES)

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61970-405 has been prepared by IEC Technical Committee 57:
Power systems management and associated information exchange.
The text of this standard is based on the following documents:
FDIS Report on voting
57/888/FDIS 57/907/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
A list of all parts of the IEC 61970 series, under the general title Energy Management System
Application Program Interface (EMS-API), can be found on the IEC website.

61970-405 © IEC:2007(E) – 5 –
The committee has decided that the contents of this publication will remain unchanged until

the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in

the data related to the specific publication. At this date, the publication will be

• reconfirmed;
• withdrawn;
• replaced by a revised edition, or

• amended.
A bilingual version of this publication may be issued at a later date.

– 6 – 61970-405 © IEC:2007(E)
INTRODUCTION
This part of IEC 61970 is part of the IEC 61970 series that defines Application Program

Interfaces (APIs) for an Energy Management System (EMS). The IEC 61970-4XX and

IEC 61970-5XX series documents comprise Component Interface Specifications (CISs). The

IEC 61970-4XX series CIS are specified as Platform Independent Models (PIMs), which

means they are independent of the underlying technology used to implement them. PIM

specifications are also referred to as Level 1 specifications. The IEC 61970-5XX series CIS,

on the other hand, are specified as Platform Specific Models (PSMs). PSM specifications are

also referred to as Level 2 specifications.

IEC 61970-4XX CISs specify the functional requirements for interfaces that a component (or
application) should implement to exchange information with other components (or
applications) and/or to access publicly available data in a standard way. The component
interfaces describe the specific event types and message contents that can be used by
applications for this purpose.
IEC 61970-405 specifies an interface for the efficient transfer of event messages and alarm
acknowledge messages in a distributed environment. Small numbers of messages are
transferred with short delay but also large amounts are transferred in short time but with
possibly longer delay. This is a typical requirement for a SCADA system that acts as a real
time data provider to other sub-systems. Other systems than SCADA may also benefit from
the characteristics of Generic Eventing and Subscription (GES) interface. When short delay
times as well as bulk message transfer is required, GES is a good fit.
The component interface specifications refer to entity objects for the power system domain
that is defined in the IEC 61970-3XX series, including IEC 61970-301.

61970-405 © IEC:2007(E) – 7 –
ENERGY MANAGEMENT SYSTEM
APPLICATION PROGRAM INTERFACE (EMS-API) –

Part 405: Generic Eventing and Subscription (GES)

1 Scope
The IEC 61970-405 Generic Eventing and Subscription (GES) specification specifies a
generalized interface for efficient exchange of messages. The specification takes into account
the latencies caused by a Local Area Network (LAN) providing efficient data exchange also
over Local Area Networks. The Generic Eventing and Subscription (GES) API is expected to
provide one of the primary means for accomplishing application integration. Beyond the scope
of the GES API, other APIs address the high performance, real-time interactive needs of an
application within a running system as well as request/reply oriented generic data access.
IEC 61970-405 is derived from the Object Management Group (OMG) Data Acquisition from
Industrial Systems section Alarms and Events (DAIS A&E) specification. OMG DAIS A&E
relies on the OMG Data Access Facility (DAF) and OPC Alarms and Events (A&E)
specifications. OMG DAIS A&E is a Platform Specific Model (PSM) with CORBA as the
platform and OPC A&E is a PSM with Microsoft COM as the platform. Implementers wanting
an introduction to OMG DAIS A&E and OPC A&E shall read these documents.
The GES interface is intended to interoperate with other IEC 61970 based interfaces. Hence it
is possible to use information retrieved from other interface to access the same information
using this interface, for example:
• object identifiers,
• attribute names or identifiers,
• class names or identifiers.
The way data is organized in a server implementing the GES interface can be seen by using
the browse interfaces for data and meta data. It is also possible to use the data access
interface directly without using the browse interfaces if the client has an a priori knowledge of
object, class and attribute identifiers. Object identifiers may be retrieved using data from other
interfaces, for example a CIMXML file or the IEC 61970-404 interface. Information on what
classes and attributes are available will be described in IEC 61970-45X documents.
IEC 61970-405 describes the functionality in a technology independent way, it is a Platform

Independent Specification (PIM). Hence, it explains the functionality to a level that can be
used to create PSMs or be an introduction to existing PSMs, i.e. DAIS A&E and OPC A&E.
Implementers wanting an introduction to OMG DAIS A&E and OPC A&E should read these
documents.
IEC 61970-405 consists of two parts:
• SCADA alarms and events that is the Platform Independent Specification (PIM) derived
from DAIS A&E and OPC A&E. This part is called “Generic Eventing and Subscription
Alarms and Events” (GES A&E).
• Generic messaging that is a generalization of the SCADA alarms and events. This part is
just called “Generic Eventing and Subscription” (GES).
IEC 61970-1 provides the EMS-API reference model upon which this standard is based. In
that reference model, the terminology used in this part of IEC 61970 is introduced and the role
of the CIS is explained.
– 8 – 61970-405 © IEC:2007(E)
IEC 61970-401 provides an overview and framework for the CIS (IEC 61970-4XX)

standards.IEC 61970-402 provides the base services to be used in conjunction with other

IEC 61970-4XX documents. This specification extends the Common Services to provide an

event subscription oriented mechanism for applications to exchange CIM data.

The mapping of IEC 61970-405 to implementation specific technologies or Platform Specific

Models (PSMs) is further described in a separate series of documents, i.e. the future

IEC 61970-5XX. For actual implementations, the future IEC 61970-5XX, OMG DAIS A&E,

OMG DAF or OPC A&E are used.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 61970-1:2005, Energy management system application program interface (EMS-API) –
Part 1: Guidelines and general requirements
IEC/TS 61970-2, Energy management system application program interface (EMS-API) –
Part 2: Glossary
IEC 61970-301:2005, Energy management system application program interface (EMS-API) –
Part 301: Common Information Model (CIM) base
IEC 61970-401, Energy management system application program interface (EMS-API) –
Part 401: Component Interface Specification (CIS) Framework
IEC 61970-402, Energy management system application program interface (EMS-API) –
Part 402: Component Interface Specification (CIS) – Common Services
Data Acquisition from Industrial Systems section Alarms and Events (DAIS A&E), OMG
Adopted Specification Version1.1, formal/2005-06-01 June 2005 (Referred herein as 'OMG
DAIS A&E')
Utility Management System (UMS) Data Access Facility (DAF), OMG Adopted Specification,
Version 2.0.1, formal/05-06-03, July 2005 (Referred to herein as ‘OMG DAF’)
OPC Alarms and Events Specification, Version 1.10, OPC Foundation, October 2002
(Referred to herein as ‘OPC A&E’)

3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC/TS 61970-2 apply.
NOTE Refer to International Electrotechnical Vocabulary, IEC 60050, for general glossary definitions.
4 Generic Eventing and Subscription (Normative)
4.1 Overview
4.1.1 General
Figure 1 illustrates the interaction between a Generic Eventing and Subscription Alarms and
Events (GES A&E) client and server. A subscription means that the server has no a priori

61970-405 © IEC:2007(E) – 9 –
knowledge of its clients. Once a connection is established, a server calls the clients back

when data becomes available or updated.

Client
Establish
Transfer of
connection
alarms and events
and subscribe
Server
IEC  1322/07
Figure 1 – Data subscription
This Clause discusses Generic Eventing and Subscription (GES) that is a generalization of
the Generic Eventing and Subscription Alarms and Events (GES A&E). GES A&E is described
in Clause 5. The scope of GES A&E is intended for SCADA data exchange, as described in
Clause 5. GES A&E Simple Events can be applied to a much broader scope and is the basis
for GES.
4.1.2 Suitability of the GES to the integration of a variety of application categories
The use of GES is not limited to SCADA oriented data. Application categories exchanging non
SCADA data that GES can be applied to include:
• Outage Management Systems
• Network Applications
• Generation Control
• Geographic Information Systems
• Energy Management Systems
• Asset and Work Management Systems
• Other application categories used in the operation of a power system as listed in
IEC 61970-1 (2005) Annex B.
4.1.3 Suitability of the GES to the integration beyond the control center

Though the target of this IEC standard is the control center technical domain, GES
encompasses a general set of concepts that can be applied to many types of systems.
Examples of these systems include:
• Customer Information Systems
• Substation Automation Systems. For integration with Substation Automation Systems, it
shall be noted that several specifications related to communication already exists, for
example the IEC 61850 series for substation communication and IEC 60870-5 for RTU
communication. The intention of this part of IEC 61970 is to describe a service interface
that may encapsulate such communication solutions.
• Other types of technically oriented operational business systems.
In recognition that the integration between applications in two or more of these systems is
often necessary, the intent of this part of IEC 61970 is to meet general GES requirements to
the extent that they are common to different types of systems while effectively addressing
control center needs.
– 10 – 61970-405 © IEC:2007(E)

4.1.4 Suitability of the GES to the integration of tightly coupled and loosely coupled

applications (informative)
Over the last couple of years, the software community has come to realize that different

software architectures are required when integrating tightly coupled applications (for example

transmission network applications deployed in a utility control center) versus loosely coupled
applications (e.g. distribution network application applications deployed as Web Services). In

the case of tightly coupled applications, the integrating architecture might be based on

CORBA IIOP, Java RMI, Microsoft DCOM or even a centralized database. In the case of

loosely coupled integration, however, it is generally accepted that an XML-based messaging

architecture is preferred. One goal of the GES is to allow a component to be developed

without prior knowledge of the deployment environment. Thus, for example, components with

a GES interface may be tied together via a CORBA remote procedure call based or an XML
message bus based infrastructure.
In accordance with IEC 61970-1, the GES is a component interface and does not include
access to middleware specific functionality such as messaging Quality of Service (QOS).
Even though the GES does not provide a message broker-oriented interface, the GES can be
used as an interface for a component adapter that in turn accesses a message broker-based
interface such as JMS or OAMAS for example.
GES specializations are possible for the following interface technologies, some of which are
language-specific and some of which are middleware-specific:
• C++ language.
• C language.
• CORBA.
• COM.
• Java.
• XML. The XML specialization will provide interoperability between independently
developed components with a GES interface when XML based messaging is used as the
integration technology. The exact format of this XML will be determined by the use of a
specification such as the W3C’s XML Protocol.
Figure 2 below illustrates how a component with a language or interface technology-specific
specialization of the GES Interface can be adapted to run over a middleware-specific
implementation. Thus, in cases where an application component has been developed using a
particular language-specific specialization such as CORBA, the use of a component adapter
would allow components to communicate using a particular middleware such as XML
messaging. Thus, the GES is independent of what transport technology is used for example
IIOP or XML Protocol.
61970-405 © IEC:2007(E) – 11 –

Component execution environment

(e.g. Java, .Net, or CORBA container)

CORBA, Java, or
.Net component
Language or interface technology
specific GES-based interface
specialization. (e.g., C++, Java, .Net,

Corba, etc.)
Component Adapter
to Middleware
Middleware interface for XML based
messaging (e.g. JMS, MSMQ, OAMAS, etc.)
Integration Bus (IIOP, DCOM, XML Protocol, proprietary)
IEC  1323/07
Figure 2 – Component architecture
Deployment environment independence is a key facet of component interoperability as well as
a way of lowering the cost of component development. For example, this specification
provides a common way of subscribing to and filtering of small object (also called business
object) events. COM does not provide any standard way of subscribing to events related to a
particular small object (such as a particular breaker). Consequently, when running over a
Microsoft-based infrastructure, it is often up to the system integrator to supply this
functionality. Enabling subscribing component developers to add small object event filtering
functionality “out of the box” (as is done in off-the-shelf OPC clients) lowers the time and
effort required to integrate components.
Enabling small object filtering in the component does not in any way break the contract
between components, component adapters, and component execution systems. The use of
small object- based filtering does not define a middleware interface. Proof of this can be seen
in that OPC and DAIS both provide small object-based event filtering. DAIS/OPC are not used
as middleware interfaces. Rather they are used at the component interface. Middleware API’s,
such as JMS and CORBA Notification, include transport semantics such as QOS (e.g. delivery
characteristics such as reliability, priority, and expiration time) as well as administrative
functionality (e.g. event channel load balancing). QOS and administrative functionality is
specific to the middleware used. On the other hand, small object filtering is common to any
middleware used.
The use of publish/subscribe functionality exposed at a component interface means that event
filtering code does not need to be rewritten for each different implementation scenario. Event
filtering is done by a component and not by a component adapter; consequently, power
system specific (CIM-based) event filtering tools can be used instead of generic event filtering
tools. CIM-based event filtering provides for more familiar as well as more powerful and easy
to use configuration management.
Furthermore, since the GES API can be deployed independent of any application category
specific information model, GES component interfaces do not need to be recompiled when an
information model changes. Thus, application category information model changes can be
handled via declarative action rather than programmatic action.

– 12 – 61970-405 © IEC:2007(E)

4.2 Using GES A&E Simple Eventing for Generic Messaging

4.2.1 General
GES can be used to construct a document exchange system. While the High Speed Data
Access (HSDA) interface as described in IEC 61970-404 supports subscribing to

measurement, parameter and other simple data, GES A&E interface as described in Clause 5

allows components to publish and subscribe to non-measurement documents (e.g. work

orders) as opposed to collections of measurement points. The eventing interface allows

components to publish and subscribe to documents such as work orders without having to

subscribe to each individual work order property.

More precisely, the use of “Simple Events” in the GES A&E interfaces is not limited to SCADA
data. GES A&E Simple Events may contain a document-oriented payload that can be sent to
or received by an arbitrary control center application. In this way, GES A&E Simple Events
are useful for accessing the entire Common Information Model (CIM). The data transmitted
through GES interfaces is independent of the GES Interface Definition Language (IDL). That
is, the GES can be used to expose and transfer any information exchange model.
The schema for GES A&E Simple Events is generic. GES A&E Simple Events have the
following properties:
• Source – a reference to the object that generated the event. This can be either an item
such as a particular measurement or more generally the name of CIM class as well as an
application category.
• Source pathname – the fully qualified IECTC57PhysicalModel pathname for the source.
• Time stamp – the time that the event occurred.
• Message – an text string describing the event.
• Main category – for Simple Events, this field contains the resource ID of Simple Event.
• Category – the resource ID for the event type. Every category corresponds to a specific
event schema.
• Category name – the name of the event type.
• Severity – a hint from the server about the level of severity for this event.
• Properties – a list of mapped and/or indexed properties.
For example, the Source field could contain a reference to the Work Management System, the
Message field could contain “New Work Order”, the Category could contain the resource ID
for the “Transformer Installation Request” event type, the Category name field could contain
“Transformer Installation Request”, and the properties would be that data associated with a
Transformer Installation Request. As can be seen by this example, Simple Events are general

purpose in nature – that is, they can be used by any application category to exchange
information.
4.2.2 GES messages
The Common Information Model described in IEC 61970-301 defines a normalized data model
for use in integration of control center applications. Future IEC 61970-450 to IEC 61970-499
Component Interface Specifications will provide denormalized views of IEC 61970-301 data.
For example, while IEC 61970-301 objects such as transformers and loads are distinct
classes, IEC 61970-450 to IEC 61970-499 Component Interface Specifications will define
document style interface classes that may amalgamate a few properties from multiple
normalized classes such as transformers and loads. IEC 61970-450 to IEC 61970-499 CIS
documents (event types) will provide application specific ways of grouping or viewing a
collection of properties.
61970-405 © IEC:2007(E) – 13 –

4.2.3 Eventing and Subscription topic trees (informative)

Events can contain documents that are delivered asynchronously. Messages can convey

documents, but the use of the term “message” also implies a broker-oriented transport

mechanism. Thus, the term event is more generic than message.

GES Eventing is similar to the Java Messaging Service (JMS) Interface with one important

distinction; GES Eventing does not include access to messaging-specific functionality such as

message broker service QOS. However, since GES Eventing is a component interface that is
independent of what middleware is deployed between components, the lack of a messaging

specific interface is appropriate.

The JMS Publish/Subscribe model defines how components use JMS to publish and subscribe
to messages related to a well-known node in a content-based hierarchy. GES Eventing calls
these nodes Areas and JMS calls these nodes topics. By relying on the area/topic as an
intermediary, event/message publishers are kept independent of subscribers and vice versa.
Many messaging service providers, such as MQSeries, group topics into hierarchies and
provide various options for subscribing to parts of the hierarchy. GES Area strings consist of
an array of area names (fully qualified pathnames) created as a result of navigating a
hierarchical area map. Neither GES Eventing nor JMS places any restriction on what an
area/topic object represents. It might be a leaf in a topic hierarchy or it might be a larger part
of the hierarchy (for subscribing to a general class of information).
Frequently, users like to see data organized in accordance with a well-known topic hierarchy.
GES does not standardize the presentation of well-known (e.g. CIM based) hierarchical views.
IECTC57 Namespaces as described in IEC 61970-402 Common Services specification is used
with GES in the same way that OPC Batch is used with OPC Data Access and OPC Alarms
and Events by providing a means by which servers can present well-known hierarchical views.
The use of the IECTC57 Namespaces together with the IArea/ICategory/IType (refer to
Figure 7) interfaces provide the base for CIM-oriented subscription. Thus, GES with Common
Services provide a standard mechanism for describing how CIM objects are ordered in a
hierarchy as well as a way for components to use those hierarchies when setting up event
(document) subscriptions.
4.2.4 Subscription filtering
GES subscription filtering provides the ability to specify property values that are used to
qualify a subscription. In SQL terms, this addition to the GES Filtering is equivalent to adding
a “where” clause. For example, a subscriber can indicate that it wishes to receive New
Transformer Installation events as well as indicate that it only wants to receive New
Transformer Installation events pertaining to transformers produced by a given manufacturer.
A GES Subscription object (refer to Figure 7) maintains a filter specification set up by a client.

The filter is used to specify what notifications shall be sent to the client. A server may support
various filter functions and a client can ask the Subscription Home object what filter functions
are supported. The subscription home is also used to create any number of subscription
manger objects. Each subscription manger is associated with a client that has implemented
callback object so that the server can send alarm and event notifications to the client.
4.2.5 GES Publish/Subscribe wildcards
4.2.5.1 General
GES Eventing does not support “wild card” functionality in topic subscription strings. For
example, GES Eventing allows components to subscribe to events on the basis of event
Category (e.g. “Transformer Installation Request”) or on the basis of topics (e.g. all work
orders for breakers), but there is no facility to choose all areas at a given level. This
specification extends GES Eventing with support for wildcards in topic based filtering. The
GES Events interfaces are not changed in order to add support for wild cards in area paths.

– 14 – 61970-405 © IEC:2007(E)

This specification requires a well-known URI for the wildcard. The URI for the wildcard is:

http://omg.org/schema/GES#WILDCARD

4.2.5.2 Example topic hierarchies (informative)

To illustrate how subscription topic trees are used, consider a topic tree that consists of a CIM

containment model hierarchy as shown in Figure 3. An example area string created by

navigating the above tree might be “IECTC57PhysicalModel/NorthArea/AirportSubstation”. In

this case, a subscriber could receive all events that pertain to this topic – including breaker,
transformer, and load-related events. However, if one wants to subscribe to breaker related

events from all substations, then the GES requires that the user specifically includes the

name of each substation node one may be interested in. This specification includes the added

capability to create an area string (array of area names) without having to manually navigate
to every node on is interested in. Such a topic string may appear as “IECTC57
PhysicalModel/*/*/Breakers”.
IECTC57Physical
Model
North Area
Industrial Blvd
Airport
Sub
Sub
Breaker 12 Load 22 Transformer 32 Breaker 13 Transformer 33
IEC  1324/07
Figure 3 – Populated namespace example for IECTC57PhysicalModel (informative)
4.2.6 Browsing IECTC57 namespaces with GES
4.2.6.1 General
IEC 61970-402 Common Services defines three trees or sub-trees used for topic based
subscriptions:
• IECTC57PhysicalModel
• IECTC57ClassModel
• IECTC57ISModel
IECTC57PhysicalModel contains subscription topic nodes representing the containment
hierarchy of instances of CIM classes, for example control areas, substations, bays, breakers,
Figure 7).
etc. To browse this hierarchy, GES uses the IArea browse interface (refer to
IECTC57ClassModel contains subscription topic nodes representing the class hierarchy of
CIM classes, for example the Power System Resource class, AC Conducting Equipment
class, Switch class, Breaker class, etc. To browse this hierarchy, GES uses the IType browse
interface (refer to Figure 7).
IECTC57ISModel contains subscription topic nodes representing the hierarchy of events
types. To browse this hierarchy, GES uses the ICategory interface (refer to Figure 7).
Using OPC with GES, clients browse all subscription topic nodes with Area browsing by
putting them into the same tree. The single OPC namespace tree may be divided into the
three sub trees: IECTC57PhysicalModel, IECTC57ClassModel, and IECTC57ISModel. As data

61970-405 © IEC:2007(E) – 15 –

describing the properties is different depending on the sub-tree in question, the GES

approach is to have sub-tree specific browsers returning data specific for the sub-trees, i.e.

IArea and IType and ICategory (refer to Figure 7) for the IECTC57PhysicalModel,

IECTC57ClassModel, and IECTC57ISModel topic trees respectively. Therefore, GES

browsing does not required three sub trees. Using GES, IECTC57PhysicalModel,

IECTC57ClassModel, and IECTC57 ISModel are the roots of independent topic trees.

4.2.6.2 Mapping GES browsing to OPC browsing

4.2.6.2.1 General
In order to compensate for the lack of native support for Resource ID’s and Type in OPC,

special properties shall be introduced into a GES compliant OPC namespace.
4.2.6.2.2 Custom property required for Resource ID
OPC differs from DAIS in that only names can be used to subscribe to events. In order to
facilitate a consistent mapping from OPC to DAIS, every node in an OPC implementation of
the IECTC57 Namespaces shall have a custom property defined named “Resource ID”. This
property contains the value of the Resource ID for that object. The OPC Custom Property
Index for this property shall be 10 000. The format of this property shall be an ASCII string
representation of hex digits: {xxxxxxxx-xxxxxxxx-xxxxxxxx-xxxxxxxx}.
4.2.6.2.3 Custom property required for Resource Type
OPC differs from GES in that only names can be used to subscribe to events. In order to
facilitate a consistent mapping from OPC to GES, every node in an OPC implementation of
the IECTC57 Namespaces shall have a custom property defined named “Resource ID”. This
property contains the value of the Resource ID for that object. The OPC Custom Property
Index for this property shall be 10 001. The value of this custom property for items in the
IECTC57PhysicalModel shall be the same as GES Type in the IECTC57ClassModel.
4.2.6.2.4 Custom property required for Type Resource ID
OPC differs from GES in that only names can be used to subscribe to events. In order to
facilitate a consistent mapping from OPC to GES, every node in an OPC implementation of
the IECTC57PhysicalModel Namespace shall have a custom property defined named “Type
Resource ID”. This property contains the value of the Resource ID for the type of that object.
The OPC Custom Property Index for this property shall be 10 002. The format of this property
shall be an ASCII string representation of hex digits: {xxxxxxxx-xxxxxxxx-xxxxxxxx-xxxxxxxx}.
4.2.6.2.5 Custom property required for Generic Data Access Type

OPC differs from GES in that only names can be used to subscribe to events. In order to
facilitate a consistent mapping from OPC to GES, every attribute node in an OPC
implementation of the IECTC57 Namespaces shall have a custom property defined named
“Generic Data Access Type”. This property identifies the GDA Simple Value data type of the
attribute. The OPC Custom Property Index for this property shall be 10 003.
4.2.6.2.6 Custom property required for Modelled
OPC differs from GES in that only names can be used to subscribe to events. In order to
facilitate a consistent mapping from OPC to GES, every attribute node in an OPC
implementation of the IECTC57ISModel Namespace shall have a custom property defined
named “Modelled”. This property indicates if the attributes can be mapped to a resource ID
using the ResourceIDService. For attributes that can be mapped, the value of this property is
the ASCII string “Mapped”. For attributes that cannot be mapped, the valued of this property
is the ASCII string “Indexed”. The OPC Custom Property Index for this property shall be
10 004.
– 16 – 61970-405 © IEC:2007(E)

5 Generic Event Subscription Alarms and Events

5.1 Background (informative)
For historical reasons, control systems for different industrial processes have evolved along

different lines. Control systems for power systems have evolved on a UNIX base and control

systems for most other industrial processes have evolved on a Windows base. For Windows

based control systems, OPC has become the dominating standard. For UNIX based systems,

the DAIS API defined in Common Object Request Broker Architecture (CORBA) Interface
Definition Language (IDL) has been developed. DAIS is based on OPC to benefit from the
success of OPC and enable easy bridging to OPC. Whith this intent, Object Management

Group (OMG) started in 1997 to develop a CORBA based interface with the same functionality

as OPC. GES A&E has the functionality from OMG DAIS A&E and OPC A&E described in a
technology neutral way, hence GES A&E is intended to be a Platform Independent Model
(PIM).
5.2 SCADA use case (informative)
Alarms are generated with the intent to gain attention to fault conditions that need operator
intervention. Hence alarms are recorded and presented to operators. The presentation usually
involves acoustic annunciation and some highlighting, for example red colour and/or blink etc.
Events are more general and may be generated due to various reasons and are distributed to
clients that have interests in the specific information topics. GES A&E can be used to monitor
and control a power system consisting of the following major parts:
• Process instrumentation making sensor data and actuation capabilities available.
• Remote terminal units (RTUs) or substation control systems reading sensor data and
controlling actuators.
• Process communication units connecting to RTUs or substation control systems.
• SCADA subsystem making processed sensor data and control capabilities available to
operators, applications or other systems.
• An Energy Management System (EMS) using the SCADA subsystem for extended
processing and control.
In a SCADA/EMS, the SCADA subsystem typically takes care of the presentation of alarms
and events related to field devices. In such a system, the data flows as shown in Figure 4.
...