Correlation
Summarize
Summary of Correlation
Correlation in ServiceNow enables synchronization of records between separate instances by establishing a link between local and remote records. This synchronization ensures that changes in records on one instance propagate to the correlated records on another instance. Correlation can be implemented using two methods: Classic correlation fields and Integration Hub Correlation records.
Show less
Classic Correlation Field
Before Integration Hub Remote Process Sync, correlations were limited to record types having a Correlation ID field, primarily Configuration Item, Service, and Task records. The Correlation ID stores the globally unique ID of a remote record and creates a one-to-one relationship between a local and a remote record. Changes in the remote record propagate to the local record using this ID. However, classic correlation fields do not track the remote system identity or the correlation state, and they require manual management by administrators.
Integration Hub Correlation Records
Integration Hub Remote Process Sync introduces dedicated Correlation [ihsynccorrelation] records, enhancing classic correlation capabilities. Each Correlation record contains:
- Local Correlation ID: A unique identifier generated by Remote Process Sync representing the correlation on the local system, acting as a stable alias.
- Remote Correlation ID: A unique identifier representing the correlation on the remote system, also acting as an alias to prevent breakage.
- Local Table: The table monitored for changes to create or update correlated records.
- Local Record: The actual record linked to the correlation, similar to the classic Correlation ID field.
- Remote System: The remote instance involved in synchronization; each correlation record links to one remote instance.
- State: Indicates whether the correlation is active (synchronizing changes) or inactive (paused but queryable for auditing).
These correlation records are managed automatically by Integration Hub Remote Process Sync, and direct manual edits are discouraged to prevent synchronization issues or data loss.
Key Benefits for ServiceNow Customers
- Correlation records allow automated and robust management of synchronization across multiple instances.
- They provide clear identification of the remote system involved in each correlation.
- Enable correlating one local record with multiple remote systems simultaneously by creating multiple correlation records.
- Support activation and deactivation of correlations, offering flexibility in synchronization control.
- Use distinct Correlation IDs separate from actual record sysids, enhancing stability and preventing broken links during record changes.
Overall, Integration Hub Correlation records improve synchronization reliability, provide better tracking and control, and reduce manual administrative overhead for ServiceNow customers managing multi-instance integrations.
Establish a synchronization relationship between records that reside on separate instances.
A correlation identifies record data from a remote instance you want to use on a local instance. An integration can use data from a correlated remote record to update a local record. Typically, integrations correlate records to synchronize them and ensure that record changes propagate across instances.
- Classic correlation field
- Integration Hub Correlation records
Classic correlation field
Prior to Integration Hub Remote Process Sync, you could only create correlations with a limited set of record types that had a Correlation ID field. By default, the Correlation ID field is only available to Configuration Item, Service, and Task records. The Correlation ID field stores the globally unique ID of a matching remote record. The Correlation ID identifies the remote record whose data values should be used to update the local record. For example, suppose incident record INC100001 correlates to problem record PRB123456 on a remote instance. Whenever changes are made to fields in remote problem PRB123456, the system uses the Correlation ID to identify that local incident INC100001 receives the same field updates.
A classic correlation creates a one-to-one relationship between a record on the local system and a record on a remote system. One local record can only ever correlate to one remote record. The correlation provides no information about the remote system nor the current state of the correlation. Administrators manually manage classic correlations from the records being updated.
Integration Hub Correlation records
Integration Hub Remote Process Sync extends the functionality of classic correlation with the introduction of dedicated Correlation [ih_sync_correlation] records.
- Local Correlation ID
- The globally unique ID that identifies the correlation on the local system. By default, Integration Hub Remote Process Sync generates a unique sys_id value for this field. The distinct sys_id acts as an alias which prevents the correlation from breaking due to changes in the local record. When Integration Hub Remote Process Sync sends this ID value to a remote system, the receiving instance uses it as the Remote Correlation ID.
- Remote Correlation ID
- The globally unique ID that identifies the correlation on the remote system. By default, Integration Hub Remote Process Sync generates a unique sys_id value for this field. The distinct sys_id acts as an alias which prevents the correlation from breaking due to changes in the remote record. When Integration Hub Remote Process Sync sends this ID value to a remote system, the receiving instance uses it as the Local Correlation ID.
- Local Table
- The table where the correlation creates or updates records. An Integration Hub Remote Process Sync capture definition monitors this table for record changes. Integration Hub Remote Process Sync uses this field to find correlations by table name.
- Local Record
- The record created or updated by a correlation. This field stores the same value as the Correlation ID field from a classic correlation. When other business logic makes changes to this record, the changes do not overwrite the correlation.
- Remote System
- The remote instance where Integration Hub Remote Process Sync sends and receives record changes. Each correlation record can only refer to one remote instance. To correlate the same local record to multiple remote systems simultaneously, you can create multiple correlation records.
- State
- The synchronization state of the correlation. Active correlations receive additions and updates. Inactive correlations do not produce additions or updates, but can be queried for auditing purposes and reactivated as needed.
- Allow management of correlations by Remote Process Sync
- Identify the remote system associated with a correlation
- Provide separate Correlation ID values for the local and remote systems
- Allow correlation of a single local record with multiple remote systems
- Allow correlations to be deactivated and reactivated as needed
- Allow Correlation ID values to be distinct from the sys_id of a remote record