内容

• 特性
• 方法
• 详细描述

ServerDiscovery QML Type

Provides information about available servers. 更多...

导入语句：	import QtOpcUa
Since:	QtOpcUa 5.13

• 所有成员列表，包括继承成员

特性

• connection : Connection
• count : int
• discoveryUrl : string
• status : Status

方法

• ApplicationDescription at ( index )

详细描述

Allows to fetch and access information about servers known to a server or discovery server.

QtOpcUa.Connection {
    id: connection
    backend: availableBackends[0]
    defaultConnection: true
}
QtOpcUa.ServerDiscovery {
    discoveryUrl: "opc.tcp://127.0.0.1:43344"
    onServersChanged: {
        if (status.isGood) {
            if (status.status == QtOpcUa.Status.GoodCompletesAsynchronusly)
                return; // wait until finished
            if (count > 0) {
                // choose right server
                endpointDiscovery.serverUrl = at(0).discoveryUrls[0];
                console.log("Using server URL:", endpointDiscovery.serverUrl);
            } else {
                // no servers retrieved
            }
        } else {
            // Fetching servers failed
            console.log("Error fetching server:", servers.status.status);
        }
    }
}
QtOpcUa.EndpointDiscovery {
    id: endpointDiscovery
    onEndpointsChanged: {
        if (status.isGood) {
            if (status.status == QtOpcUa.Status.GoodCompletesAsynchronusly)
                return; // wait until finished
            if (count > 0) {
                // choose right endpoint
                console.log("Using endpoint", at(0).endpointUrl, at(0).securityPolicy);
                connection.connectToEndpoint(at(0));
            } else {
                // no endpoints retrieved
            }
        } else {
            // Fetching endpoints failed
            console.log("Error fetching endpoints:", status.status);
        }
    }
}
					

特性文档编制

connection : Connection

The connection to be used for requesting information.

If this property is not set, the default connection will be used, if any.

另请参阅 Connection and Connection::defaultConnection .

count : int

Current number of servers in this element. Before using any data from this server discovery, you should check status if retrieval of the information was successful.

另请参阅 status and Status .

discoveryUrl : string

URL of the server to retrieve the list of servers from. Every time the URL is changed, a request to the given server is started.

When starting the request, the list of available servers is cleared and the status is set to Status.GoodCompletesAsynchronously . Once the request is finished, status changes. Make sure to check the status before acessing the list of servers.

onServersChanged: {
        if (status.isGood) {
            if (status.status == QtOpcUa.Status.GoodCompletesAsynchronusly)
                return; // wait until finished
            if (count > 0) {
                var serverUrl = at(0).serverUrl();
                console.log(serverUrl);
            }
        } else {
            // handle error
        }
}
					

另请参阅 ApplicationDescription , status , at , count ，和 Status .

status : Status

The current status of this element. In case the last retrieval of servers was successful, the status should be Status.Good .

if (status.isGood) {
    // Choose endpoint to connect to
} else {
    // handle error
}
					

另请参阅 Status .

方法文档编制

ApplicationDescription at ( index )

Returns the application description at given index . In case there are no servers available or the index is invalid, an invalid application description is returned. Before using any returned data, you should check status if retrieval of the information was successful.

if (servers.status.isGood) {
    if (servers.count > 0)
        var serverUrl = at(0).serverUrl();
        console.log(serverUrl);
        // Choose endpoint to connect to
} else {
    // handle error
}
					

另请参阅 count , status ，和 ApplicationDescription .