FOKUS Broker

Overview

The development process for the Fraunhofer FOKUS Broker is based on the OSGi [1] environment that runs in a Java Virtual Machine (JVM). Three different options are available to integrate services:

1. Service Component Architecture (SCA) [2] based OSGi bundles
2. Imported protocol services can be integrated as REST, SOAP or RMI
3. Composition scripts on State Chart XML (SCXML) [3] basis can be installed and executed.

OSGi Service Platform

The OSGi Service Platform is a dynamic module system for Java. The platform has its origins in the area of embedded systems, but is now an open standard that is available for server-based run time environments. Services running on the OSGi Platform are installed as bundles that are units of Java classes and other resources. A bundle is in principle a normal archive file and has the same structure as Java archive (jar) files. The existent manifest file (MANIFEST.MF) that is used for metadata is extended to describe bundle specific characteristics.

Import of Services

The imported services are externally located network service endpoints like REST or SOAP based Web Services. Services may be automatically integrated by providing the service endpoint and are available in the framework afterwards. This approach provides an additional way of reusing already existing services. Technically, outside-hosted services can be integrated by referencing on service endpoints, for example a WSDL file in case of SOAP based communication. Based on the service description the framework automatically generates Java code that is packed into an OSGi bundle. The new Java classes can be used to access the Web Service via Java methods. The bundle is registered in the framework and can then be used by other integrated service bundles.

SCXML

The integration of composed services has been realized by using SCXML. It represents a graphical representation of finite state machines. This language provides general-purpose functionality for orchestrating processes and is an abstract event based language. The specification by W3C has a modular approach as the functionality is defined in logical units. This approach allows defining profiles using different modules to get variants of the language.

Integrated Services exported via APIs

The FOKUS Broker has already integrated services realized in the Open SOA Telco Playground. Using standardized APIs, those services can be used by third party developers. The standardized interfaces exported by the FOKUS Broker are specified in OMA NGSI [4] and GSMA One API [5]. Services available on the Broker:

• NGSI Call Control and Configuration

• NGSI Context Management

• NGSI Data Configuration and Management

• ParlayX Multimedia Messaging extended with REST If

• SMS

• Payment

Developer Guidelines

The guidelines accessible at this webpage help developers to get fast access to the full capabilities of the FOKUS Broker. Therefore the Broker Developers Guide gives a detailed overview in the fields of service-creation, -deployment and -discovery. Additionally parts about how to use the included policy engine, the monitoring facilities as well as the user management and configuration are finalizing the generic overview of the Service Delivery Platform (SDP) designed by Fraunhofer FOKUS.

To get an insight of how to use the integrated services exported via open APIs like NGSI or GSMA One API, please also have a look at the Developer Guidelines – NGSI document. In this document the REST architecture and the therefore created resources are described in detail. Some code snippets shall help third party developers in getting fast results in service creation utilizing

[1] OSGi http://www.osgi.org

[2] SCA OSOA http://www.osoa.org

[3] SCXML http://www.w3.org/TR/scxml

[4] OMA NGSI http://www.openmobilealliance.org/Technical/release_program/NGSI_v1_0.aspx

[5] GSMA One API http://oneapi.gsmworld.com/