Asynchronous Open Session VI

LabVIEW 2013 Help

Edition Date: June 2013

Part Number: 371361K-01

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Owning Palette: WebDAV Asynchronous VIs

Requires: Full Development System

Opens an asynchronous WebDAV session and creates an associated session handle. This VI also returns event clusters that indicate request progress and completion. After calling this VI, you can use the WebDAV session handle to perform other operations using the same connection.

You must use this VI to open a session before you can use other VIs on the WebDAV Asynchronous palette.

Note  The session handles that WebDAV Asynchronous VIs use are not compatible with WebDAV Synchronous VIs.


password is the password for the WebDAV server, if required. For example, when connecting to a real-time target, use the same password as when connecting with NI Web-based Configuration & Monitoring.
username is the username with which to access the WebDAV server, if required. For example, when connecting to a real-time target, use the same username as when connecting with NI Web-based Configuration & Monitoring.
host uri prefix specifies the root uniform resource indicator (URI) and an optional prefix for all relative URIs of the file(s) on the host or the target running the WebDAV server. A URI can be a uniform resource locator (URL), a uniform resource name (URN), or both. host uri prefix also specifies the port and whether to use SSL.

Format host uri prefix as http[s]://hostname[:port][/files]. Use https to connect using Secure Sockets Layer (SSL), which provides added security. Use http to specify a non-SSL connection. If you do not specify a port number, the default is to use 80 for non-SSL and 443 for SSL. On LabVIEW Real-Time targets, you must specify /files as the prefix.
error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
timeout ms specifies the time, in milliseconds, that the VI waits when another VI makes a request on the same session handle before it returns an error. The default is 60,000 ms, or 1 minute.
verify server? specifies whether to check the certificate of the server against the list of trusted CA certificates specified by CA certificate file. If you do not specify a list of trusted CA certificates, LabVIEW checks the server's certificate against a default list of trusted CA certificates. If TRUE, the VI verifies the identity of the server using the list of trusted CA certificates for optimal security. If FALSE, the VI does not verify the identity of the server and does not provide optimal security. However, this allows the client to accept self-signed certificates signed by the certificate creator rather than a trusted CA. The default is TRUE.
session handle out returns the unique reference to the WebDAV session.
Request Events returns an event registration reference that refers to a cluster of user events called WebDAV.
error out contains error information. This output provides standard error out functionality.

Asynchronous Open Session Details

If you want to combine WebDAV events with your own user events, wire the Request Events refnum and one or more other event registration refnums to the input terminals of a Bundle function and wire the resulting cluster to the dynamic event terminal of an Event structure. To display the dynamic event terminal, right-click the Event structure and select Show Dynamic Event Terminals. Both the WebDAV and user event data items appear in the Event Data Node on the left border of the Event structure.

Note  Do not wire the same event registration reference to multiple Event structures. Otherwise, you create a race condition between the Event structures, and only one of the Event structures receives any given event. Instead, use the Asynchronous Create Event Registration VI to create additional event registration refnums that you can wire to additional Event structures on the same WebDAV session handle.


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