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ITOM deep-dive · LessonBy , ServiceNow Trainer, 8 yrs · Published · ServiceNow · all levels

Discovery patterns

How Discovery identifies devices and applications, and how patterns replaced most probe and sensor scripting.

Quick answer

How Discovery identifies devices and applications, and how patterns replaced most probe and sensor scripting.

Key takeaways
  • Patterns replaced probe and sensor scripting for new content
  • Discovery is classify, identify, explore
  • Debug patterns against a live target through the MID server
  • Empty results usually mean credentials, not logic

The sequence

Discovery scans a range, classifies what answers, then runs identification and exploration. Classification decides what the device is, identification matches it to a CI or creates one through the identification engine, exploration collects the detail.

Probes and sensors versus patterns

Probes issue commands and sensors parse the output with JavaScript. Patterns do the same work declaratively in Pattern Designer with steps and variables, and they are far easier to debug and maintain. New content is pattern based, and custom extensions should be too.

Debugging

Pattern Designer has a debug mode that runs against a live target through a MID server and shows each step result.

  • Start from the ECC queue when nothing appears, no input means the MID never ran the job
  • Check credentials affinity, a wrong credential produces empty results rather than errors
  • Confirm the CI class in the identification section before blaming the pattern

Practice challenge

+0 XPStreak ×0
Question 1 of 2
Which stage decides whether a CI already exists?

Frequently asked questions

Do we still need probes and sensors?
Only for legacy content or edge cases. Build new extensions as patterns.
Why does Discovery create duplicate CIs?
Identification rules did not match on a strong identifier such as serial number. Fix the identification rule, not the pattern.
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