Migration

Every version of a building block publishes its own process model and data structure, so a running building block has to be moved onto a new version explicitly. The Migration tab of a building block version holds the migration plans that describe those moves.

Building block plans use the same editor as case migration plans, but they are never started by hand: a building block lives inside a case, so its plans run when a case migration moves a building block onto the plan's version.

The concepts, editor tabs, and source and target rules are documented under Cases > Migration. This page covers only what differs for building blocks.

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Finding the migration screen

1

Expand Admin in the left sidebar

2

Click Building blocks under the Configuration section

3

Click a building block to open it

4

Select the version to migrate instances into

5

Click the Migration tab

Building block migration tab

The list shows every migration plan for that version:

Column	Description
Migration plan	The plan's title
Source	The building block version the plan migrates instances from
Target	The version the plan migrates instances into — always the version the plan belongs to
Status	Not started until the plan has migrated an instance, Completed once it has
Instances migrated	How many building block instances the plan has migrated

A building block plan has no run of its own, so the status never reads Running or Completed with errors. It is a running total of the instances the plan has been applied to, not the outcome of a run.

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Differences from case migration

When this plan runs

Aspect	Building block plans
Triggers	None. The General tab shows When this plan runs instead, explaining that the plan is applied automatically by a case migration
Conditions	None. The plan applies to every building block instance the case migration brings onto this version
Manual start	Not available. There is no Start migration now button
Dry run	Not available on this tab. Dry-run the case migration instead: it walks the same chain of building block plans and reports the same problems
Results	No start or finish time, and no list of errors or warnings. A failure fails the case migration that triggered it and is reported there, because the case did not migrate either
Source	A Source building block and Source version. Naming a different building block makes this plan the bridge that carries its running instances over to this one
Add / Remove building block	The owner is the migrating building block, so these tabs nest a building block inside it, or dissolve a nested one

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Chaining plans

A chain of migration plans has to connect the version a building block instance is on to the version a case links it at. One plan may declare the whole jump, or there may be one plan per step — including a step that changes nothing, because each version publishes its own process model.

If nothing connects the two versions, or if more than one chain does, the case migration fails rather than guess, and the whole case is left untouched. Run the case migration as a dry run to check the chain before starting it.

See Cases > Migration > Building blocks for how a case decides which building block version its blocks should move to.