<%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.

The sensor can show the following:

  • Value of one defined XML node
HTTP XML/REST Value Sensor

HTTP XML/REST Value Sensor

Sensor in Other Languages

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

Remarks

  • 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?

Requirement: .NET Framework

icon-toolsThis sensor requires the Microsoft .NET Framework. .NET 4.7.2 or later must be installed on the computer running the PRTG probe, 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.

icon-book-bulbFor more information, see the Knowledge Base: Which .NET version does PRTG require?

Limited to 50 Sensor Channels

icon-i-bluePRTG 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.

Add Sensor

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

Channel Name

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

Sensor Settings

On the details page of a sensor, click the Settings tab to change its settings.

icon-i-roundUsually, 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

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.

icon-i-roundIt is not possible to enter tags with a leading plus (+) or minus (-) sign, nor tags with parentheses (()) or angle brackets (<>).

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).

Default Tags

ptfsensor

Sensor Settings

URL

Enter the URL that returns the .xml file.

icon-i-round-redThe URL must be URL encoded.

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.

icon-book-arrowsFor more information, see section Smart URL Replacement below.

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.

icon-i-roundYou can also check values in JavaScript Object Notation (JSON). See section Checking JSON below.

icon-i-roundYou 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 XML/Rest Value Sensor?

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:

  • Use the value of the selected XML node: Return the value that the sensor finds at the specified XML node. If this is a non-numerical 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 below.

Count XML Nodes

This setting is only visible if you enable the return number option 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.

Namespaces

Define whether namespaces in the .xml document are used or not:

  • Use namespaces: Process the value you enter in the XML Node (and optional property) field including possibly existing namespace information.
  • Remove namespaces: 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.

icon-book-arrowsFor more information see About Namespaces section below.

Content Type in Header

Define what to include in the header of the request sent 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.

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

icon-i-blueThe 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

icon-i-redEnsure that the HTTP header statement is valid! Otherwise, the sensor request cannot be successful.

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 this sensor does when the sensor value changes:

  • Ignore changes (default): The sensor takes no action on change.
  • Trigger 'change' notification: The sensor sends an internal message indicating that its value has changed. In combination with a Change Trigger, you can use this mechanism to trigger a notification whenever the sensor value changes.

icon-i-round-redThe change notification for this sensor can only be triggered if the returned value is a numerical value. This option does not support strings.

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.

icon-i-roundIf you want to change the Unit after having created the sensor, you can change it in the sensor's channel settings.

Debug Options

Sensor Result

Define what PRTG does with the sensor results:

  • Discard sensor result: Do not store the sensor result.
  • Write sensor result to disk (File name: Result of Sensor [ID].txt): Store the last result received from the sensor to the Logs (Sensors) subfolder of the PRTG data directory on the probe system the sensor is running on (on the Master node if in a cluster). File names: Result of Sensor [ID].txt and Result of Sensor [ID].Data.txt. This is for debugging purposes. PRTG overwrites these files with each scanning interval.
    For more information on how to find the folder used for storage, see section Data Storage.

icon-prtg-on-demandThis option is not available when the sensor runs on the Hosted Probe of a PRTG hosted by Paessler instance.

Sensor Display

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.

icon-i-roundYou can set a different primary channel later by clicking the pin symbol of a channel on the sensor's Overview tab.

Graph Type

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.
    icon-i-roundThis option cannot be used in combination with manual Vertical Axis Scaling (available in the Sensor Channel Settings settings).

Stack Unit

This field is only visible if you enable Stack channels on top of each other above. 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.

Inherited Settings

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

Click inherited_settings_button to interrupt the inheritance. See section Inheritance of Settings for more information.

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:

  • Set sensor to down immediately: Set the sensor to a Down status immediately after the first failed request.
  • Set sensor to warning for 1 interval, then set to down (recommended): Set the sensor to a Warning status after the first failed request. If the following request also fails, the sensor shows an error.
  • Set sensor to warning for 2 intervals, then set to down: Set the sensor to a Down status only after three consecutively failed requests.
  • Set sensor to warning for 3 intervals, then set to down: Set the sensor to a Down status only after four consecutively failed requests.
  • Set sensor to warning for 4 intervals, then set to down: Set the sensor to a Down status only after five consecutively failed requests.
  • Set sensor to warning for 5 intervals, then set to down: Set the sensor to a Down status only after six consecutively failed requests.

icon-i-roundSensors that monitor via Windows Management Instrumentation (WMI) always wait at least one scanning interval before they show a Down status. It is not possible to immediately set a WMI sensor to a Down status, so the first option does not apply to these sensors. All other options can apply.

icon-i-roundIf you define error limits for a sensor's channels, the sensor immediately shows a Down status. No "wait" option applies.

icon-i-roundIf a channel uses lookup values, the sensor immediately shows a Down status. No "wait" options apply.

Schedules, Dependencies, and Maintenance Window

icon-i-roundYou 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 settings here. They are active at the same time as the parent objects' settings.

Schedule

Select a schedule from the list. Schedules can be used to monitor for a certain time span (days or hours) every week.

icon-book-arrowsYou can create schedules, edit schedules, or pause monitoring for a specific time span. For more information, see section Account Settings—Schedules.

icon-i-roundSchedules are generally inherited. New schedules are added to existing schedules, so all schedules are active at the same time.

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:

  • Not set (monitor continuously): No maintenance window is set and monitoring is always active.
  • Set up a one-time maintenance window: Pause monitoring within a maintenance window. You can define a time span for a monitoring pause below and change it even for a currently running maintenance window.

icon-i-roundTo terminate a current maintenance window before the defined end date, change the time entry in Maintenance Ends to a date in the past.

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:

  • Use parent: Use the dependency type of the parent object.
  • Select a sensor: Use the dependency type of the parent object. Additionally, pause the current object if another specific sensor is in a Down status or in a Paused status caused by another dependency.
  • Master sensor for parent: Make this sensor the master object for its parent device. The sensor influences the behavior of its parent device: If the sensor is in a Down status, the device is paused. For example, it is a good idea to make a Ping sensor the master object for its parent device to pause monitoring for all other sensors on the device in case the device cannot even be pinged. Additionally, the sensor is paused if the parent group is paused by another dependency.

icon-i-roundTo test your dependencies, select Simulate Error Status from the context menu of an object that other objects depend on. A few seconds later, all dependent objects are paused. You can check all dependencies under Devices | Dependencies in the main menu bar.

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.

icon-i-round-redThis setting is not available if you set this sensor to Use parent or to be the Master sensor for parent. In this case, define delays in the parent Device Settings or in its parent Group Settings.

Access Rights

Click inherited_settings_button to interrupt the inheritance. See section Inheritance of Settings for more information.

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:

  • Inherited: Use the access rights settings of the parent object.
  • None: Users in this group cannot see or edit the object. The object neither shows up in lists nor in the device tree. Exception: If a child object is visible to the user, the object is visible in the device tree but it cannot be accessed.
  • Read: Users in this group can see the object and review its monitoring results.
  • Write: Users in this group can see the object, review its monitoring results, and edit its settings. They cannot edit access rights settings.
  • Full: Users in this group can see the object, review its monitoring results, edit its settings, and edit access rights settings.

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.

icon-book-arrowsFor more details on access rights, see section User Access Rights.

Channel Unit Configuration

Click inherited_settings_button to interrupt the inheritance. See section Inheritance of Settings for more information.

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):

  • Bandwidth
  • Memory
  • Disk
  • File
  • Custom

icon-i-roundCustom channel types can be set on sensor level only.

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.

icon-speechExample

A JSON notated section may look like the following:

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

Depending on your entries in the XML Node field, the sensor processes the respective values:

Entry in Sensor's "XML Node" Field (from Example Above)

Processed Value (from Example Above)

test

Hello World

object/value

content

object/AnotherValue

AnotherContent

object

contentAnotherContent

arraytest[1]

one

arraytest[2]

two

icon-i-round-redThe 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.

icon-i-roundIf 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.

icon-speechExample

A namespace notated section may look like the following:

<myNamespace:myNode>
  some information
</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.

Smart URL Replacement

Instead of entering a complete address in the URL field of an HTTP sensor, you can simply 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/

icon-i-round-redSmart URL replacement does not work for sensors that run on the probe device.

More

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 XML/Rest Value Sensor?

Knowledge Base: How can I use XPath with the 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?

Edit Sensor Channels

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.

Notification Triggers

Click the Notification Triggers tab to change notification triggers. For detailed information, see section Sensor Notification Triggers Settings.

Others

For more general information about settings, see section Object Settings.

Sensor Settings Overview

For information about sensor settings, see the following sections:

Keywords: