JSK 1.1 A practical Approach

1. Schlatter: JSK 1.1A practical Approach • Contents • Working with JSK 1.1 • Jini environments • Writing Jini software revisited • Important software packages in the JSK 1.1 • Usage of specific APIs • Unicast Discovery • Broadcast Discovery • Service Registration • Client Search • Leasing • Helper utilities included in JSK 1.1 • Discovery Management • Lease Management • Join Manager

2. Schlatter: Working with JSK 1.1 • Status of JSK 1.1 • JSK 1.1 (Jini Technology Starter Kit, v 1.1) was released in october 2000 by Sun Microsystems, Inc. • JSK 1.1 is the second release of JSK improving JSK 1.01. • Due to the rather short life of JSK there are yet many changes to come. • What do you get from Sun Microsystems? • Core APIs to perform all typical tasks in a Jini environment • Helper utilites which gives the programmer high level interfaces to the core APIs • Some implementations of Jini services like reggie, a lookup service, or mahalo, a transaction manager service. • User friendly API documentation in HTML format • Specification docs of Jini in pdf format • Some Jini examples • What do you need to run a Jini environment? • In addition to the JSK, one needs the JDK 1.2 (or higher) installed, since reggie is based on RMI. • All other software, like a simple HTTP server, is included in the JSK.

3. Schlatter: Jini Environments • Lookup Service • Sun shippes an implementation of a lookup service called reggie. • reggie is implemented using the activation system of Java RMI.  an activation server (rmid) has to be running • With RMI, serialized instances of objects has to be shipped over the network  a HTTP (any other file delivery protocol like FTP works as well) server has to be running • Services and Clients • Jini services and clients has to interact with Jini lookup services in a specified manner. This introduces the need of having at least all of the software pieces responsible for this interaction written in Java and running in a JVM. • Service/Client Communication • The Jini specification gives no definitions on how services and clients do communicate (or even if they have to communicate at all). • Possible communication designs: • No communication (proxy is the service) • RMI proxy • Non-RMI proxy (using as an example TCP sockets) • RMI with non-RMI proxy

4. Schlatter: Writing Jini Software • Client Structure in pseudocode • prepare for discovery • discover a lookup service • prepare a template for lookup search • lookup a service • call the service • Service Structure in pseudocode • prepare for discovery • discovery a lookup service • create information about a service • export a service • renew leasing periodically

5. Schlatter: JSK 1.1 Packages • Important Packages • net.jini.discoveryThese are utility classes and interfaces that conform to the discovery and join protocol defined in the Jini(TM) Discovery and Join Specification. find lookup services • net.jini.core.discoveryA standard utility class for finding particular lookup services.  find a particular lookup service • net.jini.lookupThese are interfaces and classes for managing discovery of lookup services. manage the discovery process • net.jini.core.lookupThese are the lookup service interfaces and classes. communicate with lookup services (e.g. register/find services) • net.jini.leaseInterfaces and classes used for lease management.  manage leases • net.jini.core.leaseThese are distributed leasing interfaces and exception classes. manipulate a distinct lease • net.jini.core.eventThe RemoteEventListener interface and related standard classes. • net.jini.spaceThe JavaSpacesTM technology package.

6. Schlatter: Specific APIs: Unicast Discovery • Packages • net.jini.core.discovery • net.jini.core.lookup • Classes • net.jini.core.discovery.LookupLocator LookupLocator(java.lang.String url); LookupLocator(java.lang.String host,int port); ServiceRegistrar getRegistrar(); • net.jini.core.lookup.ServiceRegistrar

7. Specific APIs: Broadcast Discovery • Packages • net.jini.discovery • net.jini.core.lookup • Classes • net.jini.discovery.LookupDiscovery LookupDiscovery(java.lang.String[] groups); void addDiscoveryListener(DiscoveryListener l); • net.jini.discovery.DiscoveryEventServiceRegistrar[] getRegistrars(); • net.jini.core.lookup.ServiceRegistrar • Interfaces • net.jini.discovery.DiscoverListenervoid discovered(DiscoveryEvent e); void discarded(DiscoveryEvent e);

8. Specific APIs:Service Registration • Packages • net.jini.core.discovery • net.jini.core.lookup • Classes • net.jini.core.lookup.ServiceRegistrar(= proxy for the lookup service)ServiceRegistration register(ServiceItem item, long leaseDuration); • net.jini.core.lookup.ServiceItem ServiceItem(ServiceID serviceID, java.lang.Object service, Entry[] attrSets); • net.jini.core.lookup.ServiceRegistration (= proxy for the registration) ServiceID getServiceID(); void addAttributes(Entry[] attrSets); void modifyAttributes(Entry[] attrSetTemplates, Entry[] attrSets); void setAttributes(Entry[] attrSets);

9. Specific APIs:Client Search • Packages • net.jini.core.discovery • net.jini.core.lookup • net.jini.core.entry • Classes • net.jini.core.lookup.ServiceRegistrarjava.lang.Object lookup(ServiceTemplate tmpl) ServiceMatcheslookup(ServiceTemplate tmpl, int maxMatches) • net.jini.core.lookup.ServiceTemplate ServiceTemplate(ServiceID serviceID, java.lang.Class[] serviceTypes, Entry[] attrSetTemplates); • net.jini.core.lookup.ServiceMatches ServiceItem[] items; int totalMatches ; ( items.length) • net.jini.core.lookup.ServiceItemEntry[] attributeSets; java.lang.Object service; ServiceID serviceID; • Interfaces • net.jini.core.entry.Entry

10. Specific APIs:Leasing • Packages • net.jini.core • net.jini.core.lookup • net.jini.core.lease • Classes • net.jini.core.lookup.ServiceRegistrarServiceRegistration register(ServiceItem item, long leaseDuration); • net.jini.core.lookup.ServiceRegistrationLease getLease(); • Interfaces • net.jini.core.lease.Leasevoid cancel(); void renew(long duration); long getExpiration(); ( System.currentTimeMillis() ) static long FOREVER; static long ANY;

11. Helper Utilities:Discovery Management • Interfaces and classes used for Discovery Management • Helper classes • net.jini.discovery.LookupLocatorDiscovery LookupLocatorDiscovery(LookupLocator[] locators); • net.jini.discovery.LookupDiscoveryManager LookupDiscoveryManager(String[] groups, LookupLocator[] locators,DiscoveryListener listener); net.jini.discovery DiscoveryLocatorManagement DiscoveryGroupManagement Looks after groups and multicast search Looks after unicast discovery DiscoveryManagement Looks after discovery events LookupLocatorDiscovery LookupDiscovery LookupDiscoveryManager

12. Helper Utilities:Lease Management • Helper Class • net.jini.lease.LeaseRenewalManager LeaseRenewalManager(); LeaseRenewalManager(Lease lease, long desiredExpiration,LeaseListener listener); void renewUntil(Lease lease, long desiredExpiration,LeaseListener listener); • Interfaces • net.jinj.lease.LeaseListenervoid notify(LeaseRenewelEvent e);Called by the LeaseRenewalManager when it cannot renew a lease that it is managing, and the lease's desired expiration time has not yet been reached.

13. Helper Utilities:Join Manager • Helper Class • net.jini.lookup.JoinManager JoinManager(Object obj, Entry[] attrSets,ServiceIDListener callback, DiscoveryManagement discoverMgr, LeaseRenewalManager leaseMgr);JoinManager(Object obj, /* service */ Entry[] attrSets,ServiceID serviceID, DiscoveryManagement discoverMgr, LeaseRenewalManager leaseMgr); • Usage of JoinManager • JoinManager encapsulates all of the necessary steps when registering a service and renewing the leases in all found lookup services. • Interfaces • net.jini.lookup.ServiceIDListenervoid serviceIDNotify(ServiceID serviceID);Called when the JoinManager gets a valid ServiceID from a lookup service.