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OPC
Unified Architecture
In January of 2004 the OPC Foundation tasked a
working group to create a new architecture that
would take OPC to the forefront of technology
and provide an interoperability framework that
would be viable for the next 10 years and
beyond. The first parts of this new "Unified
Architecture" were released in June, 2006.
 Why
a new Architecture?
Introductory
Articles
In-depth
Presentations
Specifications
Backward
compatibility
Collaboration
Events
Specification
release schedule
Code
deliverables and release schedule
Why a new architecture?
The existing OPC COM based specifications have
served the OPC Community well over the past 10
years, but as technology moves on so must our
interoperability standards. Here are the factors
that influenced the decision to create a new
architecture:
Microsoft
has deemphasized COM in favor of
cross-platform capable Web
Services and SOA (Service Oriented
Architecture)
OPC
Vendors want a single sent of services to
expose the OPC data models (DA, A&E, HDA
...)
OPC
Vendors want to implement OPC on
non-Microsoft systems, including embedded
devices
Other
collaborating organizations need a reliable,
efficient way to move higher level
structured data
The Unified Architecture (OPC-UA) is described
in a layered set of
specifications broken into Parts. It is
purposely described in abstract terms and in
later parts married to existing technology on
which software can be built. This layering
is on purpose and helps isolate changes in OPC-UA
from changes in the technology used to implement
it. The structure and depth of material to
absorb in learning OPC-UA is harder than the OPC
COM Specifications. It is best to read the
introductory articles
and in-depth
presentations before tackling the OPC-UA
Specifications.
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Introductory Articles
Here are the
latest published articles related to OPC-UA:
Published
OPC-UA Articles
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In-depth Presentations
Here are
downloadable presentations and videos related to
OPC-UA:
Download
OPC-UA related videos and PowerPoint presentations
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Specifications
The following Parts comprise the OPC Unified
Architecture Specification. In general they
should be read in order.
Part
1 - Concepts
Part
2 - Security
Part
3 - Address Space
Part
4 - Services
Part
5 - Information Model
Part
6 - Mappings
Part
7 - Profiles
Part
8 - Data Access
Part
9 - Alarms and Conditions
Part
10 - Programs
Part
11 - Historical Access
Part
12 - Discovery
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Backward Compatibility
To aid in a swift adoption by OPC client and
server vendors, the code
deliverables from the OPC Foundation include
the following:
A
client-side proxy used to connect an
existing COM based OPC Client to an OPC-UA
Server.
A
server-side stub used to connect a new OPC-UA
Client to any existing COM-based OPC Server.
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Collaboration
The Unified Architecture is designed
specifically to allow object and information
models defined by others (vendors, end-users,
other standards ...) to be exposed without
alteration by OPC-UA Servers. Here are some of
the other standards organizations OPC has
identified as candidates for OPC-UA companion
specifications that will describe how other data
is exposed and rendered via OPC-UA:
EDDL
in cooperation with
Fieldbus Foundation,
Hart and
Profibus.
ISA
S95 and S88
OAGiS
MIMOSA
IEC
TC57 WG13
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Events
To help jumpstart developers, architects and
other visionaries with the OPC-UA technology,
OPC hosted a
DevCon in Munich, Germany October 10-12, 2006
, and one in Tokyo, Japan November 28, 2006 and
one in the U.S. in June 2007. Check for
upcoming UA DevCons, workshops and plug-fests on
the
events page.
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Specification release schedule
The following Parts of the Specification have
been released:
Part
1 - Concepts
Part
2 - Security
Part
3 - Address Space
Part
4 - Services
Part
5 - Information Model
Part
8 - Data Access
Part
10 - Programs
Part
11 - Historical Access
The following parts of the Specification will be
released in November 2008:
Part
6 - Mappings
Part
7 - Profiles
The following Parts of the Specification will be
released in December 2008:
Part
9 - Alarms and Conditions
Part
12 - Discovery
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Code
deliverables and release schedule
In addition to the OPC-UA Specifications, the
OPC Foundation and a group of member volunteers
(UA Early Adopter Workng Group)
are creating code based deliverables to aid in
the creation of OPC-UA applications and to speed
adoption. The features include the following:
XML/text Web Service
This combination of encoding and protocol allows
OPC-UA communication using industry standard
SOAP-over-HTTP Web Services that conform to the
WS-SecureConversation specification.
UA Binary
The UA Binary encoder/decoder is used to
serialize and de-serialize messages in an
OPC-defined optimized binary format that greatly
increases speed and efficiency compared to the
XML/text encoding.
UA Binary Web
Service
This combination of encoding and protocol
attaches the UA message encoded in UA Binary to
a SOAP message. In this case all of the security
is handled within the UA binary message, allowing a
very simple SOAP stack to be used (i.e. no
dependency on WS-SecureConversation).
UA TCP
The UA TCP protocol used to transport UA Binary
messages over TCP/IP.
UA Secure Conversation
The ability to secure UA TCP communications.
UA API
The UA API provides the high level language
dependent implementation of the core OPC-UA
services defined in Part 4.
Sample Client
A
UA GUI client suitable for
testing and trouble shooting.
Sample Server
A UA Server
with APIs to facilitate customization.
DA COM Wrapper
A UA Server
that that connects to existing OPC COM DA
2.05a/3.0 Servers and provides a UA interface
for them.
AE COM Wrapper
A UA Server
that that connects to existing OPC COM AE
Servers and provides a UA interface for them.
HDA COM Wrapper
A UA Server
that that connects to existing OPC COM HDA
Servers and provides a UA interface for them.
XML-DA Wrapper
A UA Server
that that connects to existing OPC
XML-DA
Servers and provides a UA interface for them.
DA COM Proxy
An OPC DA COM Server
that connects to and exposes a DA-appropriate
subset of a UA Server.
AE COM Proxy
An OPC AE COM Server
that connects to and exposes a AE-appropriate
subset of a UA Server.
HDA COM Proxy
An OPC HDA COM Server
that connects to and exposes a HDA-appropriate
subset of a UA Server.
Query
Functionality in the
Sample Server
and Sample Client to
support the Query Service Set defined in
Part 4.
Alarms &
Conditions
Functionality in the
Sample Server
and Sample Client to
support
Part
9 - Alarms and Conditions.
Programs
Functionality in the
Sample Server
and Sample Client to
support
Part
10 - Programs.
Historical
Access
Functionality in the
Sample Server
and Sample Client to
support
Part
11 - Historical Access.
Data
Access
Functionality in the
Sample Server
and Sample Client to
support
Part
8 - Data Access.
Three separate code bases are being developed to
provide UA capability on a wide variety of
systems and environments:
ANSI C/C++
This code will be as portable as possible with
specific requirements for embedded systems. The
portability layer source code is provided for MS
Windows. Linux and other environments can be
adapted by editing the source code in a small
portability layer.
JAVA
A portable JAVA implementation. Phase 1 will
provide a JAVA API on top of the C/C++ stack.
Phase 2 will provide a pure JAVA implementation. (Environment
requirements TBD).
Microsoft
.NET
The Microsoft .NET platform code base will
utilize .NET 3.0 SP1 and the Windows Communication
Foundation (aka Indigo).
Feature/Platform
Delivery Schedule for UA Core Deliverables.
These deliverables will be available from
OPC in production-tested binary form:
√
Feature delivered.
(Additional testing will be necessary before
deployment by end-users.)
YYYY-MM
Year and Month of expected feature-complete
delivery to OPC Corporate Members.
(Additional testing will be necessary before
deployment by end-users.)
(P)
Feature is planned but delivery not yet
scheduled.
The following deliverables will be created
first to validate the UA specifications and
also to serve as sample code for UA
developers. This source code will be
available to all OPC
Corporate Members.
YYYY-MM
Year and Month of expected feature-complete
delivery to Early Adopter Program
Members.
(These dates are subject to
change based on the level of volunteer
commitment by the Early Adopter Members.)
(P)
Feature is planned but delivery not yet
scheduled.
(*)
A non-commercial JAVA Sample Client and
Server are available from
VTT Technical Research Centre of Finland.
Please email
Matti.Paljakka_AT_vtt.fi.
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