OPC-DA Client to XML-DA Server Gateway
The OPC-DA Client to XML-DA Server Gateway (XDAGW-CS) enables OPC DA client applications to access XML -DA servers.
The XML-DA Gateway offers a way to allow existing OPC DA client applications access to remote servers and to upgrade step-by-step to web services technology.
The gateway is provided in version for ASP.NET1, ASP.NET2 (optionally with WSE3) and .NET3 (WCF).
On Windows Vista the .NET3 version can be configured for different communication bindings:
- Compatibility with any XML DA web service
- High performance communication using TCP or Named Pipes transports
- Secure communication using X.509 certificates to authenticate and/or encrypt the web service access.
XDAGW-CS is an OPC DA V2/V3 compliant server with a built-in XML-DA V1.01 compliant client.
When to use the OPC XML-DA Gateways?
The XML-DA Gateways enables XML-DA clients to access devices with OPC-DA servers, respectively OPC-DA clients to access local or remote XML-DA servers. The gateways offer a simple way to upgrade step-by-step to the new XML-DA standard. The gateway can be bypassed with minimal changes when XML-DA servers/clients get available.
The gateway is a permanent solution when devices are never be upgraded because:
- the vendor offers XML-DA only in a newer model
- the device lacks the resources for OPC XML-DA
- local OPC DA clients need access to the device
Why use OPC XML-DA?
OPC XML-DA provides the foundation for multi-platform interoperability because it is based on XML instead of the Windows specific DCOM. It simplifies sharing and exchange of data amongst the various levels of the plant hierarchy (low level devices and up to enterprise systems), and to a wider range of platforms.
Unlike previous OPC data access specifications, the OPC XML-DA specification describes data exchange in an environment which assumes no persistent connection between the client and the server. This makes it suitable for a much wider range of communication systems and, since XML is text based it passes firewalls.
The XDAGW-CS Client-side Gateway is an OPC-DA Server with a built-in XML-DA client.
The gateway creates XML-DA subscriptions for all items referenced by a client and updates its data cache periodically. The clients can read data quickly out of the cache.
Access from UA Clients
An OPC UA wrapper server is available free of charge to XDAGW-CS licensees.
XDAGW-CS OPC DA servers can be accessed from UA clients through this wrapper server.
The wrapper server is an OPC Foundation UA distributable and is provided under the OPC Foundation DISTRIBUTABLE license, as-is, without support.
The XML-DA Bridge combines the server-side gateway with the XDAGW-CS client-side Gateways and enables OPC-DA clients to access remote OPC-DA servers. Both gateways are available in a .NET3 version for Windows Vista. A .NET3 (WCF) based connection can use any of the .NET3 supported bindings for either high performance or high security.
The XML-DA Bridge connects remote OP DA servers/clients using established standards. DCOM issues can be minimized without proprietary tunneling solutions.
Read the gateway overview for more information.
Due to the Web Services architecture access to OPC XML-DA servers is not as restricted to a local area network as it is for COM based OPC DA servers. Security issues are therefore more important. OPC XML-DA may also be used for data exchange with higher level systems. Such systems typically are only concerned with a small data subset.
The gateway implements effective security measures. It can be configured to restrict the server access to an item subset. E.g. make some items read-only or allow only a subset of the items to be accessed.
The XDAGW-SS gateway is provided in a version for .NET3 that can be configured for secure communication.
In communication with a .NET3 based XML DA server, any WCF communication bindings can be used, including X.509 certificates
Windows 7, Windows Vista, Windows XP, Windows 2000 or Windows Server 2003/2008
IIS with ASP.NET1
or .NET3 (WCF)