PRTG Manual: HTTP XML/REST Value Sensor

Performance impact

This sensor has a high performance impact. We recommend that you use no more than 200 of this sensor on each probe.

.NET 4.7.2 or later

This sensor requires .NET 4.7.2 or later from Microsoft on the probe system. In a cluster, install it on every cluster node. If the sensor shows the error PE087, additionally install .NET 3.5 on the probe system.

If the framework is missing, you cannot create this sensor.

For more information, see the Knowledge Base: Which .NET version does PRTG require?

Windows Server

We recommend Windows Server 2016 on the probe system for best performance of this sensor.

SRP ciphers

This sensor does not support Secure Remote Password (SRP) ciphers.

Smart URL replacement

This sensor supports smart URL replacement.

IPv6

This sensor supports IPv6.

Single node

This sensor can monitor only one single node in an .xml file and shows the value in one channel. To monitor more than one node of an .xml document, add one sensor for each target node.

Knowledge Base

• Knowledge Base: Where can I find more information about the HTTP XML/REST Value sensor?
• Knowledge Base: Which HTTP status code leads to which HTTP sensor status?

Channel Name

Enter a name for the channel that displays the value at the URL.

You can change this value later in the channel settings of this sensor.

URL

Enter the URL that returns the .xml file. If you enter an absolute URL, the sensor uses this address independently of the IP Address/DNS Name setting of the parent device.

The URL must be URL encoded.

PRTG uses a smart URL replacement with which you can use the parent device's IP address or Domain Name System (DNS) name setting as part of the URL. For more information, see section Smart URL Replacement.

XML Node (and optional property)

Enter the name of the node that this sensor checks, or enter a node name and a property name to check a property value. To obtain a value from nested tags, enter the tag names and separate them with a forward slash (/). For example, use myTag/myTagInside as XML node value.

You can also check values in JavaScript Object Notation (JSON). See section Checking JSON.

You can try to use XPath syntax here but it does not work in all cases and we do not provide any technical support for XPath issues. For more information about XPath, see the Knowledge Base: How can I use XPath with the HTTP XML/REST Value sensor?

HTTP User Name

If the URL requires authentication, enter the user name. Enter a string or leave the field empty.

HTTP Password

If the URL requires authentication, enter the password. Enter a string or leave the field empty.

Sensor Value

Define what value the sensor shows:

• Use the value of the selected XML node: Return the value that the sensor finds at the XML node. If this is a non-numeric value, the sensor shows 0.
• Use the number of occurrences of the selected XML node or its children/siblings: Return the number of occurrences found. Define further settings below.

Count XML Nodes

This setting is only visible if you select Use the number of occurrences of the selected XML node or its children/siblings above.

Define which count the sensor shows:

• Occurrences of the selected XML node: Return how often the defined XML node occurs at the URL.
• Child nodes of the selected XML node: Return the number of child nodes that exist below the node at the URL.
• Sibling nodes of the selected XML node: Return the number of sibling nodes that exist next to the node at the URL.

Name Space Handling

Define whether to use namespaces in the .xml document or not:

• Use name spaces: Process the value you enter in the XML Node (and optional property) field, possibly including namespace information.
• Remove name spaces: Ignore namespace information in the .xml document and process the value you enter in the XML Node (and optional property) field as node names only.

For more information see section About Namespaces.

Content Type

Define what to include in the header of the request that the sensor sends to the URL:

• Enable (default): This works for most web servers and is the recommended setting.
• Disable: Only very few web servers cannot handle this content type and need this setting. Try this if you get an error message with the enabled option.
• Custom: You can use a custom content type.

Custom Content Type

This setting is only visible if you select Custom above.

Enter a custom content type like text/xml or text/html.

HTTP Headers

Optionally enter a list of custom HTTP headers with their respective values that you want to transmit to the URL. The syntax of a list with header-value pairs is header1:value1|header2:value2|...|headerx:valuex

The sensor does not accept header field names that include a dash (–) character. If you want to use such an HTTP header, leave out the dash in the name. For example, enter ContentType:value instead of Content-Type:value. Example: From:[email protected]|AcceptLanguage:en-us

Make sure that the HTTP header statement is valid. Otherwise, the sensor request cannot be successful.

Remove Characters

This setting is only visible if you select Use the value of the selected XML node above.

Optionally enter a string that the sensor removes from the returned XML value.

Use this to remove any unwanted characters from the result, for example to remove a thousands separator from numeric values. Enter a string or leave the field empty.

Decimal Delimiter

This setting is only visible if you select Use the value of the selected XML node above.

If the sensor value of the returned XML node is of the type float, you can define any character as the decimal delimiter. Enter one character or leave the field empty.

Custom Message

Optionally enter a custom sensor message. Use %1 as a placeholder to automatically fill in the returned XML value. Enter a string or leave the field empty.

If Channel Value Changes

Define what the sensor does if the channel value changes:

• Ignore (default): Do nothing.
• Trigger 'change' notification: Send an internal message that indicates a change.
  In combination with a change trigger, you can use this to trigger a notification if a change occurs.

The notification for this sensor can only be triggered if the returned value is a numeric value. This option does not support strings.

Unit String

Enter the unit for the values that this sensor returns. Enter a string.

PRTG uses the unit string for display purposes and shows it in graphs, data tables, and gauges.

You can change this value later in the channel settings of this sensor.

Result Handling

Define what PRTG does with the sensor result:

• Discard result (default): Do not store the sensor result.
• Store result: Store the last sensor result in the \Logs\sensors subfolder of the PRTG data directory on the probe system. The file names are Result of Sensor [ID].txt and Result of Sensor [ID].Data.txt. This setting is for debugging purposes. PRTG overwrites these files with each scanning interval.

This option is not available when the sensor runs on the hosted probe of a PRTG Hosted Monitor instance.

In a cluster, PRTG stores the result in the PRTG data directory of the master node.

Primary Channel

Select a channel from the list to define it as the primary channel. In the device tree, PRTG displays the last value of the primary channel below the sensor's name. The available options depend on what channels are available for this sensor.

You can set a different primary channel later by clicking below a channel gauge on the sensor's Overview tab.

Graph Type

Define how this sensor shows different channels:

• Show channels independently (default): Show a graph for each channel.
• Stack channels on top of each other: Stack channels on top of each other to create a multi-channel graph. This generates a graph that visualizes the different components of your total traffic.
  You cannot use this option in combination with manual Vertical Axis Scaling (available in the channel settings).

Stack Unit

This setting is only visible if you select Stack channels on top of each other above.

Select a unit from the list. PRTG stacks all channels with this unit on top of each other. By default, you cannot exclude single channels from stacking if they use the selected unit. However, there is an advanced procedure to do so.

Example

A JSON notated section might look like the following:

{
 "test": "Hello World",
 "object": {
   "value": "content",
   "AnotherValue": "AnotherContent"
 },
 "arraytest": [
   "one",
   "two"
 ]
}

Depending on your entries in the XML Node (and optional property) field, the sensor processes the respective values:

Example

A namespace notated section might look like the following:

<myNamespace:myNode>
 some information
</myNamespace:myNode>

Downtime

In the channel table on the Overview tab, this channel never shows any values. PRTG uses this channel in graphs and reports to show the amount of time in which the sensor was in the Down status

Execution Time

The execution time

[Value]

The value of one defined XML node

This channel is the primary channel by default.