PRTG Manual: HTTP XML/REST Value Sensor
The HTTP XML/REST Value sensor retrieves an .xml file from a URL and parses it.
The sensor can show the following:
- Value of one defined XML node
- Dutch: HTTP XML/REST Waarde
- French: Valeur HTTP XML/REST
- 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
- This sensor can have a high impact on the performance of your monitoring system. Use it with care. We recommend that you use no more than 50 sensors of this sensor type on each probe.
- This sensor requires .NET 4.7.2 or later on the probe system. If the sensor shows the error PE087, additionally install .NET 3.5 on the probe system.
- This sensor does not support Secure Remote Password (SRP) ciphers.
- This sensor supports smart URL replacement.
- This sensor supports the IPv6 protocol.
- This sensor has a high performance impact.
- This sensor can monitor only one single node in an .xml file and shows the value in one channel. If you need to monitor more than one node of an .xml document, add the sensor for each target node anew.
- We recommend Windows 2012 R2 on the probe system for best performance of this sensor.
- See the Knowledge Base: Where can I find more information about the HTTP XML/REST Value Sensor?
- See the Knowledge Base: Which HTTP status code leads to which HTTP sensor status?
Requirement |
Description |
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.NET Framework |
This sensor requires the Microsoft .NET Framework. .NET 4.7.2 or later must 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.
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The Add Sensor dialog appears when you manually add a new sensor to a device. It only shows the setting fields that are required for creating the sensor. Therefore, you do not see all setting fields in this dialog. You can change (nearly) all settings in the sensor's Settings tab later.
The following settings in the Add Sensor dialog differ in comparison to the sensor's Settings tab.
Sensor Settings
Setting |
Description |
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Channel Name |
Enter a name for the channel that displays the value at the URL. |
Click the Settings tab of a sensor to change its settings.
Usually, a sensor connects to the IP Address or DNS Name of the parent device on which you created the sensor. See the device settings for details. For some sensors, you can explicitly define the monitoring target in the sensor settings. See below for details on available settings.
Setting |
Description |
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Sensor Name |
Enter a meaningful name to identify the sensor. By default, PRTG shows this name in the device tree, as well as in alarms, logs, notifications, reports, maps, libraries, and tickets.
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Parent Tags |
Shows tags that the sensor inherits from its parent device, parent group, and parent probe. This setting is shown for your information only and cannot be changed here. |
Tags |
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.
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 |
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 ( |
Setting |
Description |
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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. PRTG uses a smart URL replacement that lets you use the parent device's IP address/DNS name setting as part of the URL.
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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 separated by a forward slash (/), for example, use myTag/myTagInside as XML node value.
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HTTP Username |
If the URL requires authentication, enter the username. 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:
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Count XML Nodes |
This setting is only visible if you enable the return number option above. Define which count the sensor shows:
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Namespaces |
Define whether namespaces in the .xml document are used or not:
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Content Type in Header |
Define what to include in the header of the request sent to the URL:
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Custom Content Type |
This setting is only visible if you enable 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
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Characters to Remove |
This setting is only visible if you enable 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 enable Use the value of the selected XML node above. If the sensor value of the selected XML node is of the type float, you can define any character here, which is then handled 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 when the sensor value changes:
|
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.
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Setting |
Description |
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Result Handling |
Define what PRTG does with the sensor result:
|
Setting |
Description |
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Primary Channel |
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.
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Graph Type |
Define how different channels are shown for this sensor:
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Stack Unit |
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. |
By default, all of the following settings are inherited from objects that are higher in the hierarchy. You should 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. You then see the options described below.
For more information, see section Inheritance of Settings.
Click to interrupt the inheritance.
Setting |
Description |
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Scanning Interval |
Select a scanning interval from the dropdown list. The scanning interval determines the amount of time that the sensor waits between two scans. Choose from:
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If a Sensor Query Fails |
Select the number of scanning intervals that the sensor has time to reach and to check a device again if a sensor query fails. Depending on the option that you select, the sensor can try to reach and to check a device again several times before the sensor shows the Down status. This can avoid false alarms if the monitored device only has temporary issues. For previous scanning intervals with failed requests, the sensor shows the Warning status. Choose from:
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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.
Setting |
Description |
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Schedule |
Select a schedule from the list. You can use schedules to monitor during a certain time span (days or hours) every week. Choose from:
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Maintenance Window |
Select if you want to set up a one-time maintenance window. During a maintenance window, monitoring stops for the selected object and all child objects. They show the Paused status instead. Choose between:
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Maintenance Begins |
This setting is only visible if you enable Set up a one-time maintenance window above. Use the date time picker to enter the start date and time of the one-time maintenance window. |
Maintenance Ends |
This setting is only visible if you enable Set up a one-time maintenance window above. Use the date time picker to enter the end date and time of the one-time maintenance window. |
Dependency Type |
Select a dependency type. You can use dependencies to pause monitoring for an object depending on the status of a different object. You can choose from:
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Dependency |
This setting is only visible if you enable Select a sensor above. Click |
Dependency Delay (Sec.) |
This setting is only visible if you enable Select a sensor above. Define a time span in seconds for the dependency delay. After the master sensor for this dependency returns to the Up status, PRTG additionally delays the monitoring of the dependent objects by the time span you define. This can prevent false alarms, for example, after a server restart or to give systems more time for all services to start. Enter an integer value.
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Click to interrupt the inheritance.
Setting |
Description |
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User Group Access |
Define the user groups that have access to the sensor. You see a table with user groups and group access rights. The table contains all user groups in your setup. For each user group, you can choose from the following group access rights:
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Click to interrupt the inheritance.
Setting |
Description |
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Channel Unit Types |
For each type of channel, select the unit in which PRTG displays the data. If you define this setting on probe, group, or device level, these settings can be inherited to all sensors underneath. You can set units for the following channel types (if available):
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With the XML Node (and optional property) field, you can also check values that are returned in JSON notation under the defined URL.
A JSON notated section might look like the following: { Depending on your entries in the XML Node field, the sensor processes the respective values:
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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).
In an .xml document, tags may use namespaces.
A namespace notated section might look like the following: <myNamespace:myNode> |
If you set this sensor to Use namespaces (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 namespaces. The sensor then expects the node name only in the XML Node (and optional property) field. In the example above, this is myNode.
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 or 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.example.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.example.com/
- If you enter /help in the URL field, PRTG automatically creates and monitor the URL http://www.example.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.
KNOWLEDGE BASE
Which HTTP status code leads to which HTTP sensor status?
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?
How can I use XPath with 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?
Which .NET version does PRTG require?
For more information about sensor settings, see the following sections: