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Starter

Enabling Workflow for content apps is very hard. It's one of the main reasons why customers complain and also one reason why I have been very reluctant to install the workflow by default for DAM e.g.

The idea of this document is to provide a concept for making workflow configuration easier. When looking at info.magnolia.module.workflow.setup.WorkflowBaseModuleVersionHandler you see the problems we are dealing with when installing workflow for pages app. This is also a problem for people trying to understand how stuff work together.

By cleaning up the configuration the documentation will be easier, providing Install tasks to install or even deinstall workflow per content app will be much easier, we will solve problems we have with update tasks failing and so on.

Current Problems

I have identified two problems. First of all, in CE we never use extends for actions in content apps. Second, workflow action configuration is tedious.

...

The reason why I prefer this one is because it is generic and can be reused for confirmation dialogs. You want to open some sort of dialog before doing any action, just chain it.

Here's a code snippet from the ChainedAction prototype. One problem I ran into is that I somehow have to stop or pause the chain execution, when waiting for user input. I solved this by introducing two interfaces ChainedActionCallback and DeferredAction. If one of the action sin the chain is a DeferredAction we sto pthe execution and the Action will have to call proceed on the callback to resume execution.

Code Block

language	java
title	ChainedAction Prototype
linenumbers	true

public class ChainedAction<D extends ChainedActionDefinition> extends AbstractAction<ChainedActionDefinition> implements ChainedActionCallback {
    private final Item item;
    private final Context context;
    private final ComponentProvider componentProvider;
    private Iterator<Action> it;
    public ChainedAction(D definition, final Item item, ComponentProvider componentProvider) {
        super(definition);
        this.item = item;
        this.componentProvider = componentProvider;
        this.context = new SimpleContext();
    }
    private void prepareExecution() throws ActionExecutionException {
        Collection<Action> actions = new LinkedList<Action>();
        for (ActionDefinition actionDefinition : getDefinition().getActions()) {
            Action action = createAction(actionDefinition, item, context, this);
            actions.add(action);
        }
        this.it = actions.iterator();
    }
    @Override
    public void execute() throws ActionExecutionException {
        prepareExecution();
        executeNext();
    }
    private void executeNext() throws ActionExecutionException {
        while(it.hasNext()) {
            Action action = it.next();
            action.execute();
            if (action instanceof DeferredAction) {
                break;
            }
        }
    }

    private Action createAction(ActionDefinition actionDefinition, Object... args) throws ActionExecutionException {
        Class<? extends Action> implementationClass = actionDefinition.getImplementationClass();
        if (implementationClass == null) {
            throw new ActionExecutionException("No action class set for action: " + actionDefinition.getName());
        }
        Object[] combinedParameters = new Object[args.length + 1];
        combinedParameters[0] = actionDefinition;
        System.arraycopy(args, 0, combinedParameters, 1, args.length);
        try {
            return componentProvider.newInstance(implementationClass, combinedParameters);
        } catch (MgnlInstantiationException e) {
            throw new ActionExecutionException("Could not instantiate action class for action: " + actionDefinition.getName(), e);
        }
    }

    @Override
    public void proceed() {
        try {
            executeNext();
        } catch (ActionExecutionException e) {
            e.printStackTrace();  //To change body of catch statement use File | Settings | File Templates.
        }
    }
    @Override
    public void abort() {
    }
}

Action Composition

Meaning building more complex code and the current Action API is not flexible enough to do it the right way IMO.

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Current Problems

Action Composition