Passage Developer Guide

Step 1: Tell Passage, what it must protect: declare licensing requirements

Highlight features in your product that you want to be used under licensing protection.
If the product itself must be protected - this is the first feature named after the product.
If there are other functionality, like, say, especially clever graphical editor or contact support team function, these are features too.
Specify a feature for Passage.
- Name each feature in a product-wide unique way.
- A feature, most probably, is going to evolve, so pinpoint a particular version for each feature in its closest to release state.
- Decide, how badly you want this feature to be protected by license. We call it restriction level. It describes class of actions to be taken in case there is no proper license for the feature. Currently four of them are supported:
  - error: lack of license coverage prevents feature from running: no one must use you feature without proper license
  - fatal: the whole product is to be stopped, if this particular feature is not covered by a license
  - warn: feature execution is to be paused and a user is forced to take an action to proceed (see an ad, press any key, etc.)
  - info: light, not blocking informative action is to be taken, like log entry the feature is not licensed.
  Almost each of these actions are to be implemented on the product side.

Demand licensing: declare licensing requirements using Provide-Capability header in a bundle's MANIFEST.MF:

    Provide-Capability: licensing.feature;licensing.feature="my.company.product.support";version="1.4.8";name="Contact Support Team";level="error";provider="The Company"

Here is an example taken from Passage Operator licensing declaration:

    Provide-Capability: licensing.feature;licensing.feature="org.eclipse.passage.loc.operator.issue.personal";version="2.0.0";name="Issue Personal License";level="warn";provider="Eclipse Passage",
       licensing.feature;licensing.feature="org.eclipse.passage.loc.operator.issue.floating";version="2.0.0";name="Issue Floating License";level="warn";provider="Eclipse Passage",
       licensing.feature;licensing.feature="org.eclipse.passage.loc.operator.issue.personal.full";version="2.0.0";name="Issue full functioning Personal License";level="error";provider="Eclipse Passage",
       licensing.feature;licensing.feature="org.eclipse.passage.loc.operator.issue.floating.full";version="2.0.0";name="Issue full functioning Floating License";level="error";provider="Eclipse Passage"

Passage does not make any difference between your bundles, your licensing requirements will be located anyway.
But it's a good practice to declare licensing requirements as a part of functionality contract, in a sort of API bundle for the corresponding functionality.

Now Passage knows exactly what parts of your product is to be protected and which licenses are proper.

Step 2: Tell Passage, which services it has: configure Access Cycle

Access Cycle is an invisible part of Passage that facilitates license checks on you product's runtime.

It is highly configurable, though the configuration is quite simple: your product's code base just need to supply an instance of Framework interface available through OSGi-component implementing FrameworkSupplier interface.

We have Demo Framework, which is configured with all the services implementations we have out of the box. You can also consult with the Operator Framework, which configures Access Cycle for our Passage Operator product.

There must be exactly one Framework supplied on runtime, other configurations are treated by Passage as sabotage.

Step 3: Implant license checks

Now in all key places in the product's code base you should check if there is sufficient license coverage and take proper actions it there isn't.

Each feature, been used, must acquire a license grant and then release it after the work is done.

The only piece of data you need to communicate with Passage Access Cycle is identifier for a feature you declared to protect.

There are two main interfaces, which facilitate license checks for client code: Passage and Passage UI with Equinox-based implementations Equinox Passage and Equinox Passage UI.

Simply put, the you should cover the feature invocation into acquire-release pair of appeals to Passage Access Cycle. Generally it looks like this:

        String feature = "my.feature.identifier";
        ...
        public void protectedFunctionalityIsRequested(){
            ServiceInvocationResult<GrantLockAttempt> grant = new EquinoxPassage().acquireLicense(feature);
            if(grantIsNotAcquired(grant)) {
                handleFailure(grant.diagnostic());
                return;
            }
            keepGrant(grant.data());
            invokeProtectedFunctionality();
        }

        ...
        void protectedFunctionalityCompletedOrFailed() {
            grant.ifPresent(new EquinoxPassage()::releaseLicense);
        }

To avoid boilerplating this template among client's code, Passage supplies couple of handy units:

Licensed Runnable - use it's Default implementation or extend to cover usage of a headless feature under licensing protection.
License Runnable UI or Licensed Action - for the same purpose, but for features that can afford GUI invocation.

Solve practical tasks

Passage Operator itself is a product licensed by Passage.
Consult its source code:

MANIFEST.MF of LOC branding plug-in declares licensing requirement for the main product feature.
Feature identifier equals to the Operator product name declared in the corresponding LOC product bundle.
Extension for org.eclipse.e4.workbench.model point enables license check on the product startup.
LOC API MANIFEST.MF declares licensing requirement for 4 internal features.
An action handler appeals to Passage for one of the protected internal features invocation.
License coverage for another protected internal feature is checked inside the implementation code.
Operator Seal bundle configures Access Cycle and supplies an instance of Passage Framework.

check license on start of a product built on top of Eclipse Workbench

Having you've declared a licensing requirement for feature named after the product, use Passage Licensing Addon. It can be activated with the use of extension:

        <extension
                id="licensing"
                point="org.eclipse.e4.workbench.model">
              <processor
                      apply="always"
                      beforefragment="false"
                      class="org.eclipse.passage.lic.internal.e4.ui.addons.E4LicensingProcessor">
              </processor>
        </extension>

In case of insufficient license it'll expose standard Passage Licensing status dialog like it does for Passage Operator:

enable/disable GUI item depending on whether it's functionality is covered by a license or not

You can just aks Passage if the feature can potentially be used: no grant is to be acquired, so do not use the check for the final functionality protection.

        public final class ProtectedAction extends org.eclipse.jface.action.Action {

            private final String feature = "my.protected.feature.identifier";
            ...
            @Override
            public boolean isEnabled() {
                return new EquinoxPassage().canUse(feature);
            }
            ...

        }

protect headless implementation of a feature

Use LicensedRunnable to let us do all the license checks.
Just configure it's Default with

the feature identifier,
Runnable that implements a business-function of the feature,
handle for all not-successful responses.

        public final class Invoke {

            private final String feature = "a.feature.under.license.protection";
            private final Logger log = LogManager.getLogger(getClass());

            public void userCallsProtectedFunctionality() {
                new LicensedRunnable.Default(feature, this::doTheWork, this::handleError);
            }

            private void doTheWork() {
                // protected functionality here
            }

            private void handleError(ServiceInvocationResult<GrantLockAttempt> response) {
                log.error(new DiagnosticExplained(response.diagnostic()));
            }

        }

Access Cycle is asked ones, and if access to the feature is granted, then the protected business-code is called, otherwise failure handle is invoked.

protect action with GUI available

Use LicensedRunnableUI extension of LicensedRunnable.

        new LicensedRunnableUI(this::shell, feature, this::openWizard).run();

It gains either default Shell or the one from your particular gui context, and uses it to interact with the product's user.

If the feature is covered by a license properly, no interaction GUI elements are exposed.

If license coverage is not sufficient, then Licensing status dialog opens. It offers the user an opportunity to alter license coverage (import proper license) and rechecks it each time when the user does so.

Finally, either Passage is satisfied (the last of imported licenses worked) and your protected code is allowed to run, or, if license coverage has not been improved, configured denial handing code is invoked.

handle feature cannot be executed as it is not covered by a license case

Most appeals to Passage return an instance of Service Invocation Result. It offers rich Diagnostic.

You can expose it widely to the user with Diagnostic Dialog , if you can afford GUI, or log in some way using Diagnostic Explained string supplier.

These facilities gives the user enough information to find out the reason of denial.
There are also sufficient data to trace the logic and intermediate decisions.
If, for some particular case, the diagnostic is not enough, please file an issue for us to extend it.