public class LookupNamingService extends Object implements INamingService
LookupNamingService class provides methods for obtaining references to remote
services in a Jini LookupService. Each method of the LookupNamingService takes as
one of its arguments a ServiceTemplate to lookup the desired
service.| Constructor and Description |
|---|
LookupNamingService(LookupDiscoveryManager discoveryManager,
LeaseRenewalManager renewalManager) |
| Modifier and Type | Method and Description |
|---|---|
void |
addNamingAttributes(Object service,
Entry[] attrSets)
Add attribute sets for the service.
|
Entry[] |
getLookupAttributes(Object service)
Get the current attribute sets for the service.
|
String |
getName() |
int |
getNumberOfRegistrars() |
ServiceDiscoveryManager |
getServiceDiscoveryManager() |
ServiceItem[] |
lookup(ServiceTemplate srvTemplate,
int maxMatches,
ServiceItemFilter filter)
Queries the naming service in the managed set for service(s) that match the input criteria.
|
void |
modifyNamingAttributes(Object service,
Entry[] attrSetTemplates,
Entry[] attrSets)
Modify the current attribute sets for desired service.
|
LookupCache |
notify(ServiceTemplate tmpl,
ServiceItemFilter filter,
ServiceDiscoveryListener listener)
The
notify method allows the client-like entity to request create a new managed
set (or cache) and populate it with services, which match criteria defined by the entity, and
whose references are registered with one or more of the lookup services the entity has
targeted for discovery. |
void |
terminate()
Terminate the naming service functionality.
|
public LookupNamingService(LookupDiscoveryManager discoveryManager, LeaseRenewalManager renewalManager) throws RemoteException
RemoteExceptionpublic ServiceItem[] lookup(ServiceTemplate srvTemplate, int maxMatches, ServiceItemFilter filter)
INamingServiceEntities typically employ this method when they need infrequent access to multiple instances of services, and when the cost of making remote queries is outweighed by the overhead of maintaining a local cache (for example, because of resource limitations).
This version of lookup returns an
array of instances of ServiceItem in which each element corresponds to a
service reference that satisfies the matching criteria. The number of elements in the
returned set will be no greater than the value of the maxMatches parameter, but
may be less.
Note that this version of lookup does not provide a
blocking feature. That is, this version will return immediately with whatever number
of service references it can find, up to the number indicated in the maxMatches
parameter. If no services matching the input criteria can be found on the first attempt, an
empty array is returned. It is important to understand this characteristic because there is a
common usage scenario that can cause confusion when this version of lookup is
used but fails to discover any instances of the expected service of interest. Suppose an
entity creates a service discovery manager and then immediately calls this version of
lookup, which simply queries the currently discovered lookup services for the
service of interest. If the discovery manager employed by the service discovery manager has
not yet disovered any lookup services (thus, there are no lookup services to query) the
method will immediately return an empty array. This can be confusing when one verifies that
instance(s) of such a service of interest have indeed been started and registered with the
existing lookup service(s). To address this issue, one of the blocking versions of
lookup could be used instead of this version, or the entity could simply wait
until the discovery manager has been given enough time to complete its own (lookup) discovery
processing.
lookup in interface INamingServicemaxMatches - this method will return no more than this number of service referencesfilter - an instance of ServiceItemFilter containing matching criteria
that should be applied in addition to the template-matching employed when
searching for desired services. If null is input to this
parameter, then only template-matching will be employed to find the desired
services.ServiceItem where each element corresponds to a
reference to a service that matches the criteria represented in the input parameters; or an
empty array if no matching service can be found; null if no naming service can
be found.INamingService.lookup(net.jini.core.lookup.ServiceTemplate,
int, net.jini.lookup.ServiceItemFilter)public Entry[] getLookupAttributes(Object service) throws RemoteException
INamingServicegetLookupAttributes in interface INamingServiceservice - the service to get attributes from.RemoteExceptionpublic void modifyNamingAttributes(Object service, Entry[] attrSetTemplates, Entry[] attrSets) throws RemoteException
INamingServicemodifyNamingAttributes in interface INamingServiceservice - the service to modify the attrSet by matched
attrSetTemplates.attrSetTemplates - the templates for matching attribute setsattrSets - the modifications to make to matching setsRemoteExceptionpublic void addNamingAttributes(Object service, Entry[] attrSets) throws RemoteException
INamingServiceaddNamingAttributes in interface INamingServiceattrSets - the attribute sets to addRemoteExceptionINamingService.addNamingAttributes(Object,
net.jini.core.entry.Entry[])public int getNumberOfRegistrars()
getNumberOfRegistrars in interface INamingServicepublic String getName()
getName in interface INamingServicepublic void terminate()
INamingServiceterminate in interface INamingServiceINamingService.terminate()public LookupCache notify(ServiceTemplate tmpl, ServiceItemFilter filter, ServiceDiscoveryListener listener) throws RemoteException
INamingServicenotify method allows the client-like entity to request create a new managed
set (or cache) and populate it with services, which match criteria defined by the entity, and
whose references are registered with one or more of the lookup services the entity has
targeted for discovery. This method returns an object of type LookupCache.
Through this return value, the entity can query the cache for services of interest, manage
the cache's event mechanism for service discoveries, or terminate the cache.
An entity typically uses the object returned by this method to provide local storage of, and access to, references to services that it is interested in using. Entities needing frequent access to numerous services will find the object returned by this method quite useful because acquisition of those service references is provided through local method invocations. Additionally, because the object returned by this method provides an event mechanism, it is also useful to entities wishing to simply monitor, in an event-driven manner, the state changes that occur in the services of interest.
Although not required, a common usage
pattern for entities that wish to use the LookupCache class to store and manage
"discovered" services is to create a separate cache for each service type of interest.
notify in interface INamingServicetmpl - template to match. It uses template-matching semantics to identify the
service(s) to acquire from lookup services in the managed set. If this value
is null, it is the equivalent of passing a
ServiceTemplate constructed with all null arguments
(all wildcards).filter - used to apply additional matching criteria to any ServiceItem
found through template-matching. If this value is null, no
additional filtering will be applied beyond the template-matching.listener - object that will receive notifications when services matching the input
criteria are discovered for the first time, or have encountered a state
change such as removal from all lookup services or attribute set changes. If
this value is null, the cache resulting from that invocation
will send no such notifications.RemoteException - typically, this exception occurs when a RemoteException
occurs as a result of an attempt to export the remote
listener that receives service events from the lookup
services in the managed set.INamingService.notify(net.jini.core.lookup.ServiceTemplate,
net.jini.lookup.ServiceItemFilter, net.jini.lookup.ServiceDiscoveryListener)public ServiceDiscoveryManager getServiceDiscoveryManager()
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