<%NUMBERING1%>.<%NUMBERING2%>.<%NUMBERING3%> PRTG Manual: HTTP XML/REST Value Sensor
The HTTP XML/REST Value sensor retrieves an .xml file from a URL and parses it.
HTTP XML/REST Value Sensor
For a detailed list and descriptions of the channels that this sensor can show, see section Channel List.
Sensor in Other Languages
- Dutch: HTTP XML/REST Waarde
- French: Valeur XML/REST (HTTP)
- German: HTTP XML-/REST-Wert
- Japanese: HTTP XML/REST 値
- Portuguese: Valor HTTP XML/REST
- Russian: Значение HTTP XML/REST
- Simplified Chinese: HTTP XML/REST 值
- Spanish: Valor HTTP XML/REST
Remarks
Detailed Requirements
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.NET 4.7.2 or later
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This sensor requires .NET 4.7.2 or later to be installed on the probe system (on every cluster node, if on a cluster probe).
If the framework is missing, you cannot create this sensor.
For more information, see the Knowledge Base: Which .NET version does PRTG require?
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Add Sensor
The Add Sensor dialog appears when you manually add a new sensor to a device. It only shows the settings that are required to create the sensor. You can change nearly all settings on the sensor's Settings tab after creation.
Sensor Settings
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Channel Name
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Enter a name for the channel that displays the value at the URL.
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Basic Sensor Settings
Click the Settings tab of a sensor to change its settings.
Basic Sensor Settings
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Sensor Name
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Enter a name to identify the sensor.
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Parent Tags
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Shows tags that the sensor inherits from its parent device, parent group, and parent probe.
This setting is for your information only. You cannot change it.
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Tags
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Enter one or more tags. Confirm each tag with the Spacebar key, a comma, or the Enter key. You can use tags to group objects and use tag-filtered views later on. Tags are not case-sensitive. Tags are automatically inherited.
It is not possible to enter tags with a leading plus (+) or minus (-) sign, nor tags with parentheses (()) or angle brackets (<>).
For performance reasons, it can take some minutes until you can filter for new tags that you added.
The sensor has the following default tags that are automatically predefined in the sensor's settings when you add the sensor:
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Priority
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Select a priority for the sensor. This setting determines the position of the sensor in lists. The highest priority is at the top of a list. Choose from the lowest priority () to the highest priority ().
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Sensor Settings
Sensor Settings
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URL
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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.
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XML Node (and optional property)
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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 further documentation about XPath, see the Knowledge Base: How can I use XPath with the HTTP XML/REST Value sensor?
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HTTP User Name
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If the URL requires authentication, enter the user name. Enter a string or leave the field empty.
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HTTP Password
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If the URL requires authentication, enter the password. Enter a string or leave the field empty.
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Sensor Value
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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.
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Count XML Nodes
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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.
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Name Space Handling
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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.
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Content Type
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Define what to include in the header of the request that the sensor sends to the URL:
- Enable (recommended): 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.
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Custom Content Type
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This setting is only visible if you select Custom above. Enter a custom content type like text/xml or text/html.
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HTTP Headers
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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:johnqpublic@example.com|AcceptLanguage:en-us
Ensure that the HTTP header statement is valid. Otherwise, the sensor request cannot be successful.
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Remove Characters
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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.
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Decimal Delimiter
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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.
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Custom Message
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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.
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If Channel Value Changes
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Define what the sensor does when the channel value changes:
- Ignore changes (default): Take no action on change.
- Trigger 'change' notification: Send an internal message indicating that the sensor value has changed. In combination with a change trigger, you can use this mechanism to trigger a notification whenever the sensor value changes.
The notification for this sensor can only be triggered if the returned value is a numeric value. This option does not support strings.
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Unit String
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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.
If you want to change the unit after sensor creation, you can change it in the sensor's channel settings.
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Debug Options
Debug Options
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Result Handling
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Define what PRTG does with the sensor result:
- Discard result: 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.
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Sensor Display
Sensor Display
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Primary Channel
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Select a channel from the list to define it as the primary channel. In the device tree, the last value of the primary channel is always displayed 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.
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Graph Type
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Define how different channels are shown for this sensor:
- 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).
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Stack Unit
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This setting is only visible if you enable Stack channels on top of each other as Graph Type. Select a unit from the list. All channels with this unit are stacked 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.
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Inherited Settings
By default, all of these settings are inherited from objects that are higher in the hierarchy. We recommend that you change them centrally in the root group settings if necessary. To change a setting for this object only, click under the corresponding setting name to disable the inheritance and to display its options.
For more information, see section Inheritance of Settings.
Scanning Interval
Scanning Interval
For more information, see section Root Group Settings, section Scanning Interval.
Schedules, Dependencies, and Maintenance Window
You cannot interrupt the inheritance for schedules, dependencies, and maintenance windows. The corresponding settings from the parent objects are always active. However, you can define additional schedules, dependencies, and maintenance windows. They are active at the same time as the parent objects' settings.
Schedules, Dependencies, and Maintenance Window
For more information, see section Root Group Settings, section Schedules, Dependencies, and Maintenance Window.
Access Rights
Access Rights
For more information, see section Root Group Settings, section Access Rights.
Channel Unit Configuration
Which channel units are available depends on the sensor type and the available parameters. If no configurable channels are available, this field shows No configurable channels.
Channel Unit Configuration
For more information, see section Root Group Settings, section Channel Unit Configuration.
Checking JSON
With the XML Node (and optional property) field, you can also check values that are returned in JSON notation under the defined URL.
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:
Entry in Sensor's "XML Node (and optional property)" Field (from Example Above)
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Processed Value (from Example Above)
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test
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Hello World
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object/value
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content
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object/AnotherValue
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AnotherContent
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object
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contentAnotherContent
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arraytest[1]
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one
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arraytest[2]
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two
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The sensor converts whitespaces in JSON keys into underscores (_). So, for example, if you look for the node some node in the JSON, you need to enter some_node into the node field. If you count the number of nodes (for example, some_node), both some node and some_node would be counted if they appear in the JSON.
If a key exists more than once in the JSON, the value of the first appearance is returned (no difference between whitespace and underscore).
About Namespaces
In an .xml document, tags may use namespaces.
Example
A namespace notated section might look like the following:
<myNamespace:myNode>
some information
</myNamespace:myNode>
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If you set this sensor to Use name spaces (this is the default setting), it expects the full node name, including the namespace information, in the XML Node (and optional property) field. In the example above, this is myNamespace:myNode.
If your node names are unique even without the namespace information, you can simplify the settings by setting this sensor to Remove name spaces. The sensor then expects the node name only in the XML Node (and optional property) field. In the example above, this is myNode.
Smart URL Replacement
Instead of entering a complete address in the URL field of an HTTP sensor, you can only enter the protocol followed by a colon and three forward slashes (this means that you can enter either http:/// or https:///, or even a simple forward slash / as the equivalent for http:///). PRTG automatically fills in the parent device's IP Address/DNS Name in front of the third forward slash.
Whether this results in a valid URL or not depends on the IP address or Domain Name System (DNS) name of the parent device. In combination with cloning devices, you can use smart URL replacement to create many similar devices.
For example, if you create a device with the DNS name www.mycompany.com and you add an HTTP sensor to it, you can provide values in the following ways:
- If you enter https:/// in the URL field, PRTG automatically creates the URL https://www.mycompany.com/
- If you enter /help in the URL field, PRTG automatically creates and monitor the URL http://www.mycompany.com/help
- It is also possible to provide a port number in the URL field. It is taken over by the device's DNS name and is internally added, for example, http://:8080/
Smart URL replacement does not work for sensors that run on the probe device.
Channel List
Which channels the sensor actually shows might depend on the target device, the available components, and the sensor setup.
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Downtime
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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 in percent.
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Execution Time
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The execution time in milliseconds (msec)
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[Value]
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The value of one defined XML node
This channel is the primary channel by default.
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More
Knowledge Base
Where can I find more information about the HTTP XML/REST Value sensor?
Which HTTP status code leads to which HTTP sensor status?
Which .NET version does PRTG require?
What security features does PRTG include?
How can I use XPath with the HTTP XML/REST Value sensor?
Is there a tool available that can help me build queries for the HTTP XML/REST Value sensor?
How do I extract values from XML nodes (with nested tags) using the HTTP XML/REST Value sensor?
Why does my HTTP XML/REST Value sensor return a 404 error?
My HTTP sensors don't work. What can I do?
For which sensor types do you recommend Windows Server 2012 R2 or later and why?