BT Advanced Communications Engineering Introduction - What is Jini Technology? v Set of Java APIs & distributed network protocols built on top of RMI – object hierarchies…. v Distributed Programming Model built on top of RMI and organised as federation of services (JVMs) v Services – hardware devices, software, etc. v New network capabilies – SN, AC, SOD
BT Advanced Communications Engineering Jini Example Digital camera service Image/Persistent storage service Djinn Client Printer service
BT Advanced Communications Engineering How Jini Works v Runtime Infrastructure – lookup services, jini-service providers & jini clients provides mechanisms for adding, using and removing services via Discovery, Join & Lookup v Programming Model Helps build a distributed system as a federation of services and consists of 3 parts: 1. Leasing 2. Transactions 3. Distributed Event Model
BT Advanced Communications Engineering Discovery Protocol v Jini enabled device drops presence announcement v monitor port for presence announcement packets v Send Service. Registrar object to client/service v Client/service can then invoke methods on this object
BT Advanced Communications Engineering The Join Process v A “service” connects to a Lookup Service via the Service. Registrar object received during Discovery v A “service” sends information “Service. Item” about itself through the Service. Registrar to the Lookup service v The Lookup Service stores this information and associates the service with the group v At this point, the service has joined the group on that Lookup Service
BT Advanced Communications Engineering The Lookup Process 2. Perform Discovery & get back Service. Registrar object 3. Send Service. Template using registra. lookup(template) Lookup Server 1. Register printer service with Lookup Service 4. Lookup service performs query & sends back matching service objects as return values of lookup() Printer Service 5. Client invokes methods on the service proxy object to interact directly with the printer 6. Printer prints document & notifies client via a remote event Client
BT Advanced Communications Engineering Remote PDA (Palm V) Printing Lookup Service with List of Service Items 1. Register Hello. Word. Service with Lookup Service 1. Register Bank service with Lookup Service Hello. World. Service Bank Service 2. Find Lookup Services 1. Register Printer Service with Lookup Service 3. Download Printer Service proxy 4. Send document to printer using methods on the service object Print Proxy 5. Print document Printer service Client
BT Advanced Communications Engineering Conclusion v Set of protocols for building self-healing, robust distributed networks organised as federations of services v Adds new capabilities to networking, e. g. spontaneous networking, services-on-demand & automatic configuration. v Achieves this via its 5 main concepts of Discovery & Join, Lookup, Leasing, Remote Event Model and Transactions
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