ASP.NET Sample Applications

ASP.Net applications can easily access OPC servers by using the XMLDA.NET client component.

Access to OPC servers from ASP.NET applications requires more management than access from .Net desktop applications. This is mostly because of the connection-less nature of web application, while DCOM OPC servers are connection based.

XMLDA.NET handles this issue, the .Net wrapping and the required data buffering. The ASP.NET OPC client applications are developed as OPC XML DA clients. The XMLDA.NET component handles all conversions required to access OPC DA servers.

Download the XMLDA.NET client component evaluation for the VB.NET and C# source code of sample application.

A read access for example requires only a single function call:
    XmlServer Srv = new XmlServer(ServerId.Text);
    RequestOptions opt = new RequestOptions();
    ReadRequestItemList iList = new ReadRequestItemList();
    iList.Items = new ReadRequestItem[3];
    iList.Items[0] = new ReadRequestItem();
    iList.Items[0].ItemName = "SimulatedData.Ramp";
    iList.Items[1] = new ReadRequestItem();
    iList.Items[1].ItemName = "SimulatedData.Random";
    iList.Items[2] = new ReadRequestItem();
    iList.Items[2].ItemName = "SimulatedData.Sine";
    ReplyItemList rslt ;
    OPCError[] err;
    ReplyBase reply = Srv.Read( opt, iList, out rslt, out err );

The sample applications are installed on our web server and can be tested without downloading anything.
Visit the following URLs to access the OPC DA simulation server installed on our web server.

www.advosol.us/ASPNETSamples/Read/Read.aspx	Simple application that reads three items.
www.advosol.us/ASPNETSamples/Poll/Poll.aspx	Simple application that creates a subscription for three items and makes polled refresh.
www.advosol.us/ASPNETSamples/Interactive/sample.aspx	Browses the server and subsribes/polles the selected items.