Package equip.discovery

A multicast-based peer-to-peer discovery module, based on the design of JINI discovery, but for discovering strings (such as dataspace URLs).

See:
Description

Interface Summary

ANNOUNCEMENT_EXPIRE_COUNT	default no. missed announcements to assume expiry.
ANNOUNCEMENT_INTERVAL_S	default inter-announcement interval (JINI is 120s).
ANNOUNCEMENT_STARTUP_DELAY_S	default delay range on service startup (JINI is 15s).
DISCOVERY_ATTEMPTS	default request repeats (JINI is undefined).
DISCOVERY_GROUP	default multicast address for discovery (JINI is 224.0.1.85).
DISCOVERY_GROUP_ANY	group wildcard = empty string as in JINI
DISCOVERY_GROUP_DEFAULT	default/open group
DISCOVERY_INTERVAL_S	default inter-request interval (JINI is undefined).
DISCOVERY_PORT	default port for multicast messages (JINI is 4160).
DISCOVERY_TTL	default multicast TTL for discovery and announcement.
DISCOVERY_VERSION	Discovery protocol version

Class Summary

DataspaceServer
DiscoveryBrowser	A Swing tree-based browser for the discovery service.
DiscoveryBrowser.UrlNodeInfo	url and last refresh time
DiscoveryClientAgent	Client support for discovery.
DiscoveryClientAgentImpl
DiscoveryClientAgentImpl.HeardInfo	heard info
DiscoveryEventListener	callback interface for client discovery
DiscoveryEventListenerImpl
DiscoveryRendezvous	unicast reflector (with some filtering) for non-multicast discovery.
DiscoveryRequest	Discovery request is this serialised into a multicast packet.
DiscoveryRequestImpl
DiscoveryServerAgent	Server support for discovery.
DiscoveryServerAgentImpl
ExampleClient
MulticastUtils	some helpers for multicast stuff
ServerAnnouncement	Announcement is this serialised into a UDP packet.
ServerAnnouncementImpl
ServerDiscoveryInfo	information on a single service.
ServerDiscoveryInfoImpl

Exception Summary

DiscoveryUrlException

Package equip.discovery Description

A multicast-based peer-to-peer discovery module, based on the design of JINI discovery, but for discovering strings (such as dataspace URLs).

In order to advertise something use DiscoveryServerAgent (see for example DataspaceServer).

In order to discover things use DiscoveryClientAgent (see for example ExampleClient).

Based in part on JINI multicast discovery request. Each advert has one or more service types, and one or more groups

. Service Type (which is something that is not present in JINI, since we are not just looking for lookup services) has the common form "<interface-class-name>:<version-identifier>".

As in JINI (and SNMP), groups are strings which must match exactly to identify common communities of action. E.g. to support concurrently deployment of different versions of the system.

Non-multicast support is provided by (a) running the DiscoveryRendezvous intelligent (i.e. selective) reflector, and using equip.eqconf to configure each client and server to use it (see the 'discoveryGroup' to the IP addresss or DNS name of the machine running the rendezvous server. Default port for the server is 4170. Other ports are random.