The ECC queue for Discovery
Summarize
Summary of The ECC queue for Discovery
The External Communication Channel (ECC) Queue is a critical integration point within ServiceNow that connects your instance to external systems, primarily through a MID Server. It holds records representing messages exchanged during all stages of the Discovery process—either as output from the instance to target systems or input from those systems back to the instance. These records provide a detailed flow of probe and sensor activities along with the XML payloads involved in discovery tasks.
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Key Features
- Content of ECC Queue: Tracks messages and data exchanged during Discovery, enabling insight into the probe and sensor operations and their results.
- Automatic Record Deletion: ECC queue records older than 7 days are deleted by default to manage storage size, but this schedule can be customized. Retaining records for at least a month is recommended for troubleshooting purposes.
- Access Points: The ECC queue can be accessed via the Discovery module or directly through the ECC module in ServiceNow, facilitating monitoring and investigation.
- Record States: Records cycle through states such as ready, processing, processed, and error, reflecting their progress and allowing for error identification and troubleshooting.
- Debugging Support: Debugging ECC queue processing is possible by using the script debugger on the same session and reviewing business rules and scripts that handle the payload.
- Configurable Properties: Properties like “Save ECC queue attachments” can be enabled to retain attachments for debugging, overriding the default behavior of deleting attachments after successful sensor processing.
Key Outcomes
- Provides a transparent and detailed communication log for Discovery activities, essential for troubleshooting and validating discovery accuracy.
- Enables efficient management of ECC queue data volume through automated cleanup schedules, while allowing customization to meet operational needs.
- Supports proactive monitoring of Discovery progress and immediate identification of issues via ECC queue record states and error tracking.
- Facilitates advanced debugging and analysis of discovery processes by preserving detailed data and allowing inspection of processing logic.
The External Communication Channel (ECC) Queue is a connection point between your ServiceNow instance and other systems that integrate with it, most commonly a MID Server.
Contents of the ECC Queue
The ECC queue contains records that are created during all stages of discovery. Each record is a message from the instance to system your are targeting for discovery, classified as output, or a message from that system to the instance, classified as input.
ECC queue records provide you with a connected flow of probe and sensor activity along with the XML payload sent to or from an instance and the assets you are targeting.
Automatic deletion of ECC queue records
As your IT Asset Discovery runs, the size of the ECC queue can grow to several gigabytes. Most of the “completed tasks” records are unnecessary, but some might be important for troubleshooting any problems.
For example, if Discovery is not properly capturing the disk drives on a particular Windows server, you can look in the ECC Queue at the data returned by the Windows - System Information probe. For this reason, you should retain ECC Queue data from Discovery for at least a month.
- ecc_queue_event
- ecc_queue
Accessing the ECC queue
The following image is an example of a record in the ECC queue. This record shows that a WMI classifier probe was instructed to run and has been processed. Note the XML payload it returned as the discovery task collected data. See The MID Server ECC queue for a description of each field.
ECC queue states
Input and output messages keep processing until the discovery is finished or terminated. You can monitor the ECC queue to see records populate during discovery and see the states of each record change.
ECC queue input records are processed by business rules (BR), but not all business rules direct these ECC queue inputs to process. As a result, some ECC queue inputs remain in a ready state.
- When new probe instructions are available for the MID Server, the system creates an output record with the state of ready.
- The MID Server then starts processing the probe instructions and the state changes to processing before it finally changes to processed.
- When a result returns to the MID Server and is ready to be sent to the instance, the system creates an input record with the state of ready.
- While the system processes the payload, the state changes to
processing before it finally changes to
processed.
If any errors are encountered, the state changes to error. You can review errors as a starting point for troubleshooting a failed discovery.
Debug processing of ECC queue records
To use a script debugger, process the payload on the same session as the debugger. Review the business rule which processes the particular ECC queue record and the actual code which processes the payload.
Properties and parameters that affect the ECC queue
| Property | Description |
|---|---|
| Save ECC queue attachments | The normal behavior for discovery sensors is to delete attachments to
ECC queue entries upon successful sensor processing. Enabling this
property overrides this behavior, and forces attachments to be preserved.
This is typically done for debugging purposes. To enable this property, navigate to . |