Table Of Contents

Header Exists (G Dataflow)

Version:
Last Modified: December 18, 2017

Determines if the header is associated with the client handle. Headers define attributes of the data exchanged between the client and server.

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client handle

Unique value that identifies the web request.

You can use the same client handle to wire together multiple HTTP nodes to preserve authentication credentials, HTTP headers, and cookies.

Client handles are not required when making web requests without persistent data such as headers or credentials.

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header

Header field included in the web requests of the client handle. The header control provides a pull-down menu with available header fields.

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error in

Error conditions that occur before this node runs.

The node responds to this input according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Default: No error

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client handle out

Unique value that returns data back to the node. You can use the same client handle to wire together multiple HTTP nodes to preserve authentication credentials, HTTP headers, and cookies. Client handles are not required when making independent web requests without persistent data such as headers or credentials.

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header exists?

A Boolean value that determines if the header is associated with the client handle.

True The specified header is associated with the client handle.
False The specified header is not associated with the client handle.
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value

Value assigned to the header. If header exists? returns False, this output returns an empty string.

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error out

Error information.

The node produces this output according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Where This Node Can Run:

Desktop OS: Windows

FPGA: This product does not support FPGA devices

Web Server: Supported in VIs that run in a web application


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