Rechtacek's

Quietly disable modules at runtime?

I was given a inquiry from user of NetBeans Platform. He wants to know a way how to disable one or more modules, in running application built on NetBeans Platform, in additional it must be perform silently, i.e. with no end-user intervention or any assistance.

Well, he requirement is clear but its fulfillment has several difficulties: first, modules in NetBeans Platform depends on each other and it's uneasy to discover modules which don't involve any essential module of platform. Second, modules could depend on each other, even thought don't declare such dependency in it meta-data. Such ad-hoc dependencies are mistakes and NetBeans architecture is aiming to avoid them but few of them can still left there. This fact leaded NetBeans team to do disabling of module only in "offline" time, it means when NetBeans application is not running currently. Despite of this, Autoupdate Services still offers this possibility even if it never called in NetBeans IDE.

Okay. It was bad news, good new is Autoupdate Services API has capability to perform disabling of module in currently running application (with awareness of possible problems stated above).

Autoupdate Services has the particular operation container for disabling modules OperationContainer.createForDirectDisable. Now I show a code snippet how to use this container for disabling some modules.

public void doDisable (Collection<String> codeNames) { // codeName contains code name of modules for disbale
    Collection<UpdateElement> toDisable = new HashSet<UpdateElement> ();
    List<UpdateUnit> allUpdateUnits = UpdateManager.getDefault ().getUpdateUnits (UpdateManager.TYPE.MODULE);
    for (UpdateUnit unit : allUpdateUnits) {
        if (unit.getInstalled () != null) { // filter all installed modules
            UpdateElement el = unit.getInstalled ();
            if (el.isEnabled ()) { // filter all enabled modules
                if (codeNames.contains (el.getCodeName ())) { // filter given module in the parameter
                    toDisable.add (el);
                }
            }
        }
    }

    OperationContainer<OperationSupport> oc = OperationContainer.createForDirectDisable ();

    for (UpdateElement module : toDisable) {
        if (oc.canBeAdded (module.getUpdateUnit (), module)) { // check if module can be disabled
            OperationInfo<OperationSupport> operationInfo = oc.add (module);
            if (operationInfo == null) { // it means it's already planned to disable
                continue;
            }
            // get all module depending on this module
            Set<UpdateElement> requiredElements = operationInfo.getRequiredElements ();
            // add all of them between modules for disable
            oc.add (requiredElements);
        }
    }

    // check the container doesn't contain any invalid element
    assert oc.listInvalid ().isEmpty ();
    try {
        // get operation support for complete the disable operation
        Restarter restarter = oc.getSupport ().doOperation (null);
        // no restart needed in this case
        assert restarter == null;
    } catch (OperationException ex) {
        Exceptions.printStackTrace (ex);
    }
}

I hope it helps to achieve the wish. If you have any problem let me know.

Posted at 01:22PM Jan 23, 2009 by Rechtacek's in NetBeans  |  Comments[6]