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Discovery Q&A: Patterns



Q&A


How do patterns take over probes?

Since the Helsinki Discovery version, patterns are replacing existing probes. The idea of this article is to start using the Pattern Designer for developing.

Creating patterns in Pattern Designer does not require knowledge of programming in Java, but you must be familiar with the Pattern Designer module. Refer to the product documentation for operational information.

You need to understand the structure of the product for which you want to create a pattern, before starting to create its pattern in Pattern Designer. Pattern Designer offers a UI for creating code.

In Pattern Designer you can choose the required operation using elements in the GUI and see this operation real-time output.

How to move from probes and sensors to patterns

To switch from a probe and sensor to a pattern, navigate to Class > CI Classification, and then select the required specific CI.

  

From there, navigate to the Triggers probes, and then choose probe Horizontal pattern and choose the related pattern that should run.

Resolving duplicate serial number issue

If the only mandatory field for the CI identifier is OS serial number and you are experiencing the issue of duplicate serial numbers, add extra fields to identify the CI.

Navigate to the CI identifier of the related CI and add an extra mandatory field. 

Documentation on Service Mapping Jakarta features

https://docs.servicenow.com/bundle/jakarta-it-operations-management/page/product/service-mapping/reference/c_ServiceMappingOverview.html

Where are there examples?

Here is the link in the Jakarta documentation that describes every operation in Pattern Designer including examples:

https://docs.servicenow.com/bundle/jakarta-it-operations-management/page/product/service-mapping/task/t_DefineDiscoveryStepsPatDef.html

Delete Strategy CMDB update

OOTB there's no cascade rule on the cmdb_ci field, record still remains.

It doesn't break data integrity in the CMDB. Any reference to a CI on the CMDB side is handled according to cascade rules.  This strategy is applied only when the CI isn't discovered, making the CI irrelevant unless it's re-discovered. The cascade rules are customizable and can be applied per specific pattern and the CI type.

Unless there is a cascade rule related tables, it won't delete the task following the same logic we apply to deleting any other tables or manually deleting CIs.

How to create related data for CIs  that extend the cmdb_ci_appl table or extend from the cmdb_ci table

Add the related table to the relevant discovery pattern. 

How to create related data for records that do not extend cmdb_ci

You cannot relate data collected for CI types that do not extend cmdb_ci, because you cannot relate these CI types to patterns. To work around this limitation, fill the lookup/related table and define them in the CI identifier. This allows you to see these CI types as temporary attributes when you activate the Debug mode in Pattern Designer. 

How and when is applicative credential syntax used

The following applicative syntax is used: command+$$user+$$password.

Run the command with the right username and password field as part of the command.

Use the tag to specify the CI that you want to use.

They are CIs that require applicative credentials to access full or additional information. 

For an example of applicative credential usage, refer to the Oracle DB pattern. 

When and how to deploy the change user operation

The Change user operation looks for OS credentails and not applicative credentails.

There are times when the general user is not enough and an OS user is needed. In this case, configure an OS user and define the Change user operation in the pattern to switch to this user.

For an example of the Change user operation, refer to the WMB pattern.

How to interact with CIs in the CMDB inside the pattern

Use the create relation/reference operation, according to the IRE rules.

How does pre/post processing script work

The pre/post processing script can be launched in the following cases:

  • When launching the pattern: add data from the instance to populate the context and to use this data in the pattern.
  • Before sensor process: after the pattern runs and before processing the payload, for example, make serial number validation before we do the payload processing.
  • After sensor process : to complete missing data, for example for creating references between CIs created from the payload that cannot be done in the pattern, for example, DNS.
How does metadata rules editor really work

The metadata editor defines relations for dependent CIs. Check if such a relation exists by checking CI identifier, there is the checkbox if the CI is independent. 

In the metadata editor, you define the only relation options between two CIs. 

How to use the Create relation operation to properly create relationships

You need to know which CI is a parent and which CI is a child. The parent is the CI, which holds the relation.   

Pattern debug doesn't run unless it's associated with a trigger probes in a process classifier

To use a pattern in the Debug Mode, you must:

  • If it is a host: classify it at least, because if you want to debug a pattern you must know which host it runs on, because you need credentials and you must know which commands are relevant.
  • If it is an application: you must recognize the process, because application patterns are based on the process information.
What's the preferred way: Javascript vs groovy

There is no exact answer for that. Most of the time javascript is preferred but it is not accurate for all cases. 

What interfaces are supported

Right now there are two interfaces supported: javascript and groovy.

How to hide relationships discovered to prevent showing up from the macro

Filter out or exclude certain relationships to show up in CI form or dependency map by adding them to Relationship Type exclusion list (cmdb_rel_filter table).

 

 

Article Information

Last Updated:2018-01-05 08:56:21
Published:2017-11-10
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