Extending Steep through plugins

Process chain consistency checkers

A process chain consistency checker plugin is a function that checks if an execute action can be added to a process chain or if adding it would lead to inconsistencies that render the process chain inexecutable.

The function is called before the execute action is converted to an executable and before it is added to the process chain. It takes a list of executables that have been collected so far during process chain generation, the execute action that is about to be converted, the workflow from which the process chain is being created, and a Vert.x instance.

It returns true if the execute action can safely be converted and added to the list of executables to make up a new process chain, or false if adding it would lead to a process chain that could not be executed later.

Steep will not discard actions that a consistency checker plugin has rejected. Instead, it will try to add them to another process chain later. At this point, the plugin will be called again.

If required, the function can be a suspend function.

Additional propertiesType
arrayAn optional list of names of other process chain consistency checker plugins that need to be executed before this plugin. If this property is not given, the order in which consistency checkers are applied to process chains is undefined.
Function interface
suspend fun myProcessChainConsistencyChecker(processChain: List<model.processchain.Executable>,
  action: model.workflow.ExecuteAction, workflow: model.workflow.Workflow,
  vertx: io.vertx.core.Vertx): Boolean
Example descriptor
- name: myProcessChainConsistencyChecker
  type: processChainConsistencyChecker
  scriptFile: conf/plugins/myProcessChainConsistencyChecker.kt
Example plugin script
import io.vertx.core.Vertx
import model.processchain.Executable
import model.workflow.ExecuteAction
import model.workflow.Workflow
fun dummyProcessChainConsistencyChecker(processChain: List<Executable>,
    action: ExecuteAction, workflow: Workflow, vertx: Vertx): Boolean {
  // do not add a service more than once to a process chain
  return processChain.none { it.serviceId == action.service }