Many default Liferay services are available as web services. Liferay exposes its web services via SOAP and JSON web services. If you’re running Liferay locally on port 8080, visit the following URL to browse Liferay’s default SOAP web services:

http://localhost:8080/api/axis

To browse Liferay’s default JSON web services, visit this URL:

http://localhost:8080/api/jsonws/

These web services APIs can be accessed by many different kinds of clients, including non-portlet and even non-Java clients. You can use Service Builder to generate similar remote services for your projects’ custom entities. When you run Service Builder with the remote-service attribute set to true for an entity, all the classes, interfaces, and files required to support both SOAP and JSON web services are generated for that entity. Service Builder generates methods that call existing services, but it’s up to you to implement the methods that are exposed remotely. Let’s use Service Builder to generate remote services for the Nose-ster Event Listing portlet example project. You’ll implement a few methods for the Event Listing portlet that can be called remotely via SOAP and JSON web services.

Remember: local service methods are implemented in EventLocalServiceImpl. Similarly, you’ll implement remote service methods in EventServiceImpl. Add the following methods to the EventServiceImpl class:

public Event addEvent(
       long groupId, String name, String description,
       int month, int day, int year, int hour, int minute, long locationId,
       ServiceContext serviceContext)
    throws PortalException, SystemException {

    EventListingPermission.check(
       getPermissionChecker(), groupId, EventListingActionKeys.ADD_EVENT);

    return EventLocalServiceUtil.addEvent(
       getUserId(), groupId, name, description, month, day, year, hour,
       minute, locationId, serviceContext);
}

public Event deleteEvent(long eventId)
    throws PortalException, SystemException {

    EventPermission.check(getPermissionChecker(), eventId,
       EventListingActionKeys.DELETE_EVENT);

    return eventLocalService.deleteEvent(eventId);
}

public Event getEvent(long eventId)
    throws PortalException, SystemException {

    EventPermission.check(getPermissionChecker(), eventId,
       EventListingActionKeys.VIEW);

    return EventLocalServiceUtil.getEvent(eventId);
}

public Event updateEvent(
       long userId, long eventId, String name, String description,
       int month, int day, int year, int hour, int minute, long locationId,
       ServiceContext serviceContext)
    throws PortalException, SystemException {

    EventPermission.check(getPermissionChecker(), eventId,
       EventListingActionKeys.UPDATE_EVENT);

    return EventLocalServiceUtil.updateEvent(
       userId, eventId, name, description, month, day, year, hour, minute,
       locationId, serviceContext);
}

Each remote service method performs security checks to determine whether the caller has permission to add/update/delete events. We cover Liferay’s security and permissions system in Chapter 12. To see how the Event Listing portlet is integrated with Liferay’s permissions system, browse the Event Listing portlet project available in the Dev Guide SDK at https://github.com/liferay/liferay-docs/tree/6.1.x/devGuide/code/devGuide-sdk. The project is in the SDK’s portlets/event-listing-portlet. folder.

Notice the calls to the eventLocalService field’s addEvent, updateEvent, and deleteEvent methods. The eventLocalService field holds a Spring bean of type EventLocalServiceImpl that’s injected into EventServiceBaseImpl by Service Builder. See EventServiceBaseImpl for a complete list of the Spring beans available in EventServiceImpl. These include the following:

  • counterLocalService
  • eventLocalService
  • eventService
  • eventPersistence
  • locationLocalService
  • locationPersistence
  • locationService
  • resourceLocalService
  • resourcePersistence
  • resourceService
  • userLocalService
  • userPersistence
  • userService

Notice also that we modified the deleteEvent method of the EventServiceImpl class passing it an event ID as a parameter instead of an entire event object. The method is now ready to call as a remote web service.

After you finish adding imports to EventServiceImpl, save the class and run Service Builder again.

Liferay uses Apache Axis to make SOAP web services available. Axis requires a Web Service Deployment Descriptor (WSDD) to be generated in order to make the SOAP web services available. Liferay provides a build-wsdd Ant target that generates the WSDD. In Liferay IDE or Developer Studio, when viewing your service.xml file in Overview mode, there’s a button in the top-right corner of the screen for calling the Build WSDD target. Liferay Portal makes your service’s Web Services Definition Language (WSDL) available after you’ve built its WSDD and deployed your portlet project. Let’s learn how to call your remote services next.

Calling Remote Services

Service Builder can expose your project’s remote web services both via a JSON API and via SOAP. By default, running Service Builder with remote-service set to true for your entities generates a JSON web services API for your project. You can access your project’s JSON-based RESTful services via a convenient web interface. To view the JSON web services available for the Event Listing plugin, visit the following URL:

http://localhost:8080/event-listing-portlet/api/jsonws

Each entity’s available operations are listed on the plugin’s JSON web services API page. If you’ve been implementing the Nose-ster Event Listing example portlet used throughout this chapter, you’ll be anxious to try out its remote web services. You can invoke JSON web services directly from your browser. For example, to bring up a test form for your Event entity’s delete-event operation, visit the above URL and click on its delete-event link.

invoking-sb-generated-json-ws.png

Figure 4.10: You’ll see a page displaying the name of the service method, its required parameters, its return type, possible exceptions it can throw, and a form for entering its parameters.

The only parameter required for the delete-event operation is an event ID. Since there’s no UI yet for the Event Listing application, you probably don’t have any events in your database. But if you did, you could check for an event’s ID in your Event_Event database table. Then you could enter the value into the eventId field in the test page’s Execute section and click Invoke to delete that event. Liferay returns feedback from each invocation.

Finding a portlet’s web services is easy with Liferay’s JSON web service interface. Invoking a portlet’s web services via Liferay’s JSON web service interface is a great way to test them. You can also examine alternate equivalent methods of calling the SOAP and JSON web services via JavaScript, Curl, and URLs. If you’d like to learn more about how to invoke remote services from a client application, visit the JSON Web Services tutorial. Next, we’ll consider how to implement custom SQL queries in your portlet, so you can easily leverage information from multiple entity types.

Service Builder can also make your project’s web services available via SOAP using Apache Axis. After you’ve built your portlet project’s WSDDs and deployed the project as a plugin, its services are available on the portal server. It’s easy to list your Nose-ster Event Listing plugin’s SOAP web services. You have two options: you can access them in Liferay IDE or you can open your browser to the URL for its web services.

To access your SOAP web services in Liferay IDE, right-select your portlet from under it’s Liferay server in the Servers view. Then select Test Liferay Web Services….

If you’d rather view your SOAP web services from a browser, go to the following URL:

http://localhost:8080/event-listing-portlet/api/axis

Liferay Portal lists the services available for all your entities and provides links to their WSDL documents. Clicking on the WSDL link for the Event service takes you to the following URL:

http://localhost:8080/event-listing-portlet/api/axis/Plugin_Event_EventService?wsdl 

This WSDL document lists the Event entity’s SOAP web services. Once the web service’s WSDL is available, any SOAP web service client can access it.

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