OPC XML-DA Gateways
Web service application will have to interact with the
thousands of installed OPC DA servers and clients. This requires flexible
gateways. Advosol offers gateways that differ in functionality and in their
configuration:
| XML-DA Gateways |
The XML-DA Gateways have a static configuration, defined in a
configuration file. It is possible to restrict the access to the underlying
server to a subset of the items and the access to read-only.
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| Exchange Server |
The OPC DA Exchange Server aggregates items from multiple OPC DA
servers into the Exchange Server and exchanges data between these servers.
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| UDAWeb |
The UDAWeb Universal Data Access Web Service is
dynamically configurable according the OPC DX specification. It can be accessed
from XML-DA clients and handles connections to OPC-DA and XML-DA servers.
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Available XML-DA Gateways
The XDAGW-SS
Server-side Gateway enables XML-DA clients to access OPC-DA servers. The
gateway is installed at the location of the OPC-DA servers and can be accessed
from remote XML-DA web service client applications.The device with the OPC
server does not need to be upgraded.
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The XDAGW-CS
Client-side Gateway enables OPC-DA clients to access remote XML-DA
servers.The gateway is installed at the location of the OPC-DA
client.
Applications with a built-in OPC-DA client need not be upgraded in
order to be able to access XML-DA servers.
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The XML-DA
Bridge enables OPC-DA clients to access remote OPC-DA servers.Access
over the Internet is possible without upgrading client or server.
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The Exchange
Server aggregates items from multiple OPC DA servers into the Exchange
Server and exchanges data between these servers. The Exchange Server is
accessible as an OPC DA V2/V3 server of an XML DA web service.
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The UDAWeb
Universal Data Access Web Service acts as a gateway to multiple OPC-DA
and XML-DA servers. All OPC servers installed at one location can be accessed
through one UDAWeb web service.
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Product Comparison
Advosol offers three different products with data aggregating
and/or XML DA gateway features. The capabilities differ, allowing you to
select the product best suited for you application needs.
| Feature |
|
|
|
| Runs as OPC DA V2/V3 server |
yes |
no |
no |
| Runs as XML DA ASP.NET2 web service |
yes |
yes |
yes |
| Runs as XML DA .NET3 (WCF) service |
yes |
yes |
no
|
| Number of supported OPC DA child server |
unlimited |
1 |
unlimited |
| Number of supported XML DA child servers |
0 |
0 |
unlimited |
| Simple Configuration and data transfer |
yes |
yes |
no |
| OPC DX compliant configuration and data transfer |
no |
no |
yes |
| Data transfer in both directions |
yes |
yes |
yes |
| Data transfer between child servers |
yes |
no |
no |
Gateway Configuration Concepts
The XML-DA gateway and UDAWeb solutions complement each other,
offering different configuration concepts
The XML-DA Gateway has a fix
configuration, is simple to use, highly efficient and inherently secure. UDAWeb
supports flexible configuration and access to mutliple OPC/XML servers. Some
application may require one product or the other, while many applications can be
realized with either product, depending in personal preferences.
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The UDAWeb Universal Data Access Web
Service characteristics are:
- Supports access to multiple
- OPC DA servers
- XML DA servers
- Customization module for local device access.
- Dynamic configuration. Multiple clients can modify the configuration during
operation.
- Each item connection is configured individually
- Connections support override values and substitute values
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The characteristics of the XML-DA Gateway are:
- Connection to one OPC server allows highly efficient data transfer.
- Fix configuration from local file gives high security
- Configuration is limited to restrict item acces
- Minimal configuration
required
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