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.
- 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 officially support more than 50 channels.
- This sensor does not support Secure Remote Password (SRP) ciphers.
- This sensor supports smart URL replacement.
- 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.
- 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?
This sensor requires the Microsoft .NET Framework. .NET 4.7.2 or later must be installed on the probe system, either on the local system (on every node, if on a cluster probe), or on the system running the remote probe. If the framework is missing, you cannot create this sensor.
For more information, see the Knowledge Base: Which .NET version does PRTG require?
PRTG does not officially support more than 50 sensor channels. Depending on the data used with this sensor, you might exceed the maximum number of supported sensor channels. In this case, PRTG tries to display all sensor channels. Be aware, however, that you experience limited usability and performance.
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 |
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Channel Name |
Enter a name for the channel that displays the value at the URL. |
On the details page of a sensor, click the Settings tab 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.
Basic Sensor Settings |
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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. |
Parent Tags |
Shows Tags that this sensor inherits from its parent device, group, and probe. This setting is shown for your information only and cannot be changed here. |
Tags |
Enter one or more Tags, separated by spaces or commas. You can use tags to group sensors and use tag–filtered views later on. Tags are not case sensitive. We recommend that you use the default value. There are default tags that are automatically predefined in a sensor's settings when you add a sensor. See section Default Tags below. You can add additional tags to the sensor if you like. Other tags are automatically inherited from objects further up in the device tree. These are visible above as Parent Tags.
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Priority |
Select a priority for the sensor. This setting determines where the sensor is placed in sensor lists. A sensor with a top priority is at the top of a list. Choose from one star (low priority) to five stars (top priority). |
ptfsensor
Sensor Settings |
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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 field 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 field 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:
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Unit String |
Enter the unit for the values that this sensor returns. Enter a string. This unit string is used for display purposes and is shown in graphs, data tables, and gauges.
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Debug Options |
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Sensor Result |
Define what PRTG does with the sensor results:
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Sensor Display |
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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 field 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 and should be changed there if necessary. Often, best practice is to change them centrally in the Root group's settings. For more information, see section Inheritance of Settings. To change a setting for this object only, disable inheritance by clicking the button next to inherit from under the corresponding setting name. You then see the options described below.
Scanning Interval |
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Click |
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Scanning Interval |
Select a scanning interval (seconds, minutes, or hours). The scanning interval determines the amount of time that the sensor waits between two scans. You can change the available intervals in the system administration on PRTG on premises installations. |
If a Sensor Query Fails |
Define the number of scanning intervals that the sensor has time to reach and check a device again in case a sensor query fails. Depending on the option that you select, the sensor can try to reach and check a device again several times before the sensor shows a 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 a Warning status. Choose from:
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Schedules, Dependencies, and Maintenance Window |
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Schedule |
Select a schedule from the list. Schedules can be used to monitor for a certain time span (days or hours) every week.
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Maintenance Window |
Specify if you want to set up a one-time maintenance window. During a maintenance window, the current object and all child objects are not monitored. They are in a Paused status instead. Choose between:
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Maintenance Begins |
This field 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 maintenance window. |
Maintenance Ends |
This field 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 maintenance window. |
Dependency Type |
Define a dependency type. You can use dependencies to pause monitoring for an object depending on the status of another object. You can choose from:
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Dependency |
This field is only visible if you enable Select a sensor above. Click the Search button and use the object selector to select a sensor on which the current object will depend. |
Dependency Delay (Sec.) |
This field is only visible if you enable Select a sensor above. Define a time span in seconds for dependency delay. After the master sensor for this dependency comes back to an Up status, monitoring of the dependent objects is additionally delayed by the defined time span. This can help avoid false alarms, for example, after a server restart, by giving systems more time for all services to start up. Enter an integer value.
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Access Rights |
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Click |
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User Group Access |
Define the user groups that have access to the selected object. A table with user groups and types of access rights is shown. It contains all user groups from your setup. For each user group, you can choose from the following access rights:
You can create new user groups in the System Administration—User Groups settings. To automatically set all objects further down in the hierarchy to inherit this object's access rights, set a check mark for the Revert children's access rights to inherited option.
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Channel Unit Configuration |
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Click |
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Channel Unit Types |
For each type of sensor channel, define the unit in which data is displayed. If defined 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 may 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 may 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 just 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, smart URL replacement makes it easy 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?
Knowledge Base: Is there a tool available that can help me build queries for the HTTP XML/REST Value sensor?
Knowledge Base: How do I extract values from XML nodes (with nested tags) using the HTTP XML/REST Value Sensor?
Knowledge Base: How can I use XPath with the HTTP XML/REST Value Sensor?
Knowledge Base: Why does my HTTP XML/REST Value sensor return a 404 error?
Knowledge Base: My HTTP sensors don't work. What can I do?
Knowledge Base: For which sensor types do you recommend Windows Server 2012 R2 or later and why?
Knowledge Base: Which .NET version does PRTG require?
To change display settings, spike filtering, and limits, switch to the sensor's Overview tab and click the gear icon of a specific channel. For detailed information, see section Sensor Channel Settings.
Click the Notification Triggers tab to change notification triggers. For detailed information, see section Sensor Notification Triggers Settings.
For more general information about settings, see section Object Settings.
For information about sensor settings, see the following sections: