context.arch.discoverer
Class Discoverer

java.lang.Object
  context.arch.BaseObject
      context.arch.widget.Widget
          context.arch.discoverer.Discoverer

All Implemented Interfaces:

CommunicationsHandler, MessageHandler

public class Discoverer

extends Widget

This class allows to add a discovery system to the context toolkit.

The discoverer is found by context components thanks to multicast communications. The discoverer allow them to register to it (to send their complete description), to query to it (to retrieve the description of components that fit several characteristics), to subscribe to notification (the subscriber wants to be notified when the discoverer registers a new component that fit some characteristics), to lease it (when a component registers to the discoverer, it registers for a given period that is identified by a lease), to unregister (when the component lease ends or when the components wants).

When a context component is created, it does not know the other components. And it can subscribes to another component only if it knows the component's name, port and hostname. The discoverer registers all context components when they are created, it stores for each of them their description. So that a component is able to do a request to the discoverer to get one or more context components that fit some characteristics (for example : I want all widgets that has information about Anind in the CRB)

Author:

Agathe

See Also:

context.arch.discoverer.SearchEngine, ComponentDescription, DiscovererDescription, context.arch.discoverer.query.Query, Lease, LeasesWatcher

Field Summary

static java.lang.String	ALL_RESULTS Type of query reply : returns no query id and all results (with a maximum set by
static java.lang.String	APPLICATION Component type : for application
static java.lang.String	CALLER Tag used in LOOKUP_DISCOVERER to contain the description of the caller component
static java.lang.String	CALLER_ID Tag used in LOOKUP_DISCOVERER inside CALLER tags for the component id Also used in LOOKUP_DISCOVERER_REPLY by discoverers
static java.lang.String	CASE_SENSITIVE Type of matching for the query
static java.lang.String	CLASSNAME Classname tag
static java.lang.String	COMPONENT_CLASSNAME Tag used in DISCOVERER_REGISTRATION for component classname Tag also used in DISCOVERER_QUERY
static java.lang.String	COMPONENT_ID Tag used in DISCOVERER_QUERY_REPLY to give the resulting component id
static java.lang.String	CONSTANT_ATTRIBUTE_NAME Tag used in QueryElement to query the discoverer.
static java.lang.String	CONSTANT_ATTRIBUTE_NAME_VALUES Tag used in DISCOVERER_REGISTRATION to contain the constant attributes of the component Tag also used in DISCOVERER_QUERY This tag is also used in QueryElement to query the discoverer.
static java.lang.String	CONSTANT_ATTRIBUTE_VALUE Tag used in QueryElement to query the discoverer.
static boolean	DEBUG Debug flag.
static int	DEFAULT_MAX_RESULTS Default number of responses sent in replyt to a DISOVERER_QUERY message with a ALL_RESULTS type
static int	DEFAULT_PORT Default port for discoverer to use
static java.lang.String	DISCOVERER Tag used in LOOKUP_DISCOVERER_REPLY to contain the discoverer description
static java.lang.String	DISCOVERER_DESCRIPTION_FULL_RESPONSE Tag used to determine level of detail of component description in response to subscribers
static java.lang.String	DISCOVERER_ID Tag used in LOOKUP_DISCOVERER_REPLY for the discoverer id Also used in DISCOVERER_REGISTRATION
static java.lang.String	DISCOVERER_QUERY Tag used for query messages to the discoverer
static java.lang.String	DISCOVERER_QUERY_CONTENT Tag used in DISCOVERER_QUERY messages to the discoverer
static java.lang.String	DISCOVERER_QUERY_REPLY Tag used for query reply messages to the discoverer
static java.lang.String	DISCOVERER_QUERY_REPLY_CONTENT Tag used in DISCOVERER_QUERY_REPLY_CONTENTS messages
static java.lang.String	DISCOVERER_QUERY_REPLY_CONTENTS Tag used in DISCOVERER_QUERY_REPLY messages to the discoverer
static java.lang.String	DISCOVERER_QUERY_TYPE Tag used in DISCOVERER_QUERY_CONTENT to indicate the type of query reply
static java.lang.String	DISCOVERER_REGISTRATION Message tag used by components to send to the discoverer their description
static java.lang.String	DISCOVERER_SUBSCRIBE Message tag used by components to send to the discoverer a subscription
static java.lang.String	DISCOVERER_TYPE
static java.lang.String	DISCOVERER_UNREGISTRATION Message tag used by components to unregister from the discoverer
static java.lang.String	DISCOVERER_UNREGISTRATION_REPLY Message tag used by the discoverer to reply to a DISCOVERER_UNREGISTRATION message
static java.lang.String	DISCOVERER_UPDATE Message tag used by components to send to the discoverer an update
static java.lang.String	ERROR_EMPTY_QUERY This tag is used when there is no response to the received query
static java.lang.String	ERROR_QUERY_NOT_FOUND This tag is used when a NEXT_RESULT query is received and the queryId is not reckognized
static java.lang.String	ERROR_REGISTRATION_NOT_FOUND This tag is used in error object for DISCOVERER_UNREGISTRATION_REPLY messages when the context component that want to be unregistered is not found.
static java.lang.String	FIELD_SEPARATOR Separator used to separate fields (as for constant attribute name and value)
static java.lang.String	FIRST_RESULT Type of query reply : returns the first element
static java.lang.String	HOSTADDRESS Tag used in LOOKUP_DISCOVERER inside CALLER tags for the component IP address
static java.lang.String	HOSTNAME Tag used in LOOKUP_DISCOVERER inside CALLER tags for the component hostname Also used in LOOKUP_DISCOVERER_REPLY, DISCOVERER_REGISTRATION
static java.lang.String	IGNORE_CASE Type of matching for the query
static java.lang.String	INCOMING_ATTRIBUTE_NAME_VALUES Tag used in DISCOVERER_REGISTRATION to contain the incoming attribute name values Tag also used in DISCOVERER_QUERY
static java.lang.String	INTERPRETER Component type : for interpreter
static java.lang.String	LOCATION_ADDRESS Tag used in DISOCVERER_REGISTRATION for the component location address Tag also used in DISCOVERER_QUERY
static java.lang.String	LOOKUP_DISCOVERER Message tag used by components to send a multicast message to lookup a discoverer
static java.lang.String	LOOKUP_DISCOVERER_OK Message tag used by discoverers to reply to a lookup message
static java.lang.String	LOOKUP_DISCOVERER_REPLY Message tag used by discoverers to reply to a lookup message
static java.lang.String	MAXIMUM_RESULTS Tag used if DISCOVERER_QUERY to set the maximum number of responses wanted
protected DiscovererMediator	mediator
static java.lang.String	NEW_COMPONENT This tag is the callback name used to notify subscriber of a new component
static java.lang.String	NEXT_RESULT Type of query reply : returns the next result
static java.lang.String	NON_CONSTANT_ATTRIBUTE_NAME Tag used in QueryElement to query the discoverer.
static java.lang.String	NON_CONSTANT_ATTRIBUTE_NAME_VALUES Tag used in DISCOVERER_REGISTRATION to contain the non constant attributes of the component Tag also used in DISCOVERER_QUERY
static java.lang.String	OUTGOING_ATTRIBUTE_NAME_VALUES Tag used in DISCOVERER_REGISTRATION to contain the outgoing attribute name values Tag also used in DISCOVERER_QUERY
static java.lang.String	PORT Tag used in LOOKUP_DISCOVERER inside CALLER tags for the component port Also used in LOOKUP_DISCOVERER_REPLY, DISCOVERER_REGISTRATION
static java.lang.String	PRIORITY Attribute tag used in the DISCOVERER_QUERY_CONTENT
static int	PRIORITY_1 First or weakest priority for the query element
static int	PRIORITY_2 Second or middle priority for the query element
static int	PRIORITY_3 Last or stronger priority for the query element
static java.lang.String	QUERY_ID Tag used in the DISCOVERER_QUERY_REPLY_CONTENT to give the query id
static java.lang.String	QUERY_ORDER Tag used inside the DISCOVERER_QUERY_REPLY_CONTENT to give the order of the response
static java.lang.String	QUERY_TOTAL_ANSWERS Tag used inside the DISCOVERER_QUERY_REPLY_CONTENT to give the total number of answers to the query
static java.lang.String	REGISTERER Tag used in DISCOVERER_REGISTRATION to contain the description of the component registring
static java.lang.String	REGISTERER_ID Tag used in DISCOVERER_REGISTRATION for the component id
static java.lang.String	SERVER Component type : for servers
static java.lang.String	SERVER_CALLBACKS Tag used in DISCOVERER_REGISTRATION to contain the server callback names
static java.lang.String	SERVER_CONSTANT_ATTRIBUTES Tag used in DISCOVERER_REGISTRATION to contain the server constant attributes of the component
static java.lang.String	SERVER_NON_CONSTANT_ATTRIBUTES Tag used in DISCOVERER_REGISTRATION to contain the server non constant attributes of the component
static java.lang.String	SERVER_SERVICES Tag used in DISCOVERER_REGISTRATION to contain the server service names
static java.lang.String	TEMP_DEST Tag used by communicationsObject to retrieve the destination address
static java.lang.String	TYPE Tag used in LOOKUP_DISCOVERER inside CALLER tags for the component type (baseobject(applications), widget, server, interpreter)
static java.lang.String	UPDATE_ADD_TYPE Tag used in UPDATE_TYPE message to specify the method used to update information.
static java.lang.String	UPDATE_REPLACE_TYPE Tag used in UPDATE_TYPE message to specify the method used to update information Replace type is used to remove old information before adding new one.
static java.lang.String	UPDATE_TYPE Message tag used by components to specify the update's type
static java.lang.String	WIDGET Component type : for widget
static java.lang.String	WIDGET_CALLBACKS Tag used in DISCOVERER_REGISTRATION to contain the widget callback names Tag also used in DISCOVERER_QUERY
static java.lang.String	WIDGET_SERVICES Tag used in DISCOVERER_REGISTRATION to contain the widget service names Tag also used in DISCOVERER_QUERY

Fields inherited from class context.arch.widget.Widget

attributes, attributeTypes, callbacks, CLASS, constantAttributes, constantAttributesTypes, CurrentOffset, PUT_DATA, PUT_DATA_REPLY, QUERY, QUERY_ATTRIBUTES, QUERY_ATTRIBUTES_REPLY, QUERY_CALLBACKS, QUERY_CALLBACKS_REPLY, QUERY_CONSTANT_ATTRIBUTES, QUERY_CONSTANT_ATTRIBUTES_REPLY, QUERY_REPLY, QUERY_SERVICES, QUERY_SERVICES_REPLY, QUERY_VERSION, QUERY_VERSION_REPLY, services, SPACER, storage, subscribers, TIMESTAMP, UPDATE, UPDATE_AND_QUERY, UPDATE_AND_QUERY_REPLY, VERSION, VERSION_NUMBER, WIDGET_TYPE

Fields inherited from class context.arch.BaseObject

BASEOBJECT_TYPE, communications, DISABLE_PORT, discoverer, EXIT_OK, gFrame, handlers, ID, parser, PING, PING_REPLY, QUERY_DESCRIPTION, QUERY_DESCRIPTION_REPLY, serviceHandlers

Constructor Summary

Discoverer()
Constructor that sets up internal variables for maintaining the list of widget attributes, callbacks and services.

Discoverer(int port)
Constructor that sets up internal variables for maintaining the list of discoverer attributes, callbacks and services.

Discoverer(int port, boolean storageFlag)
Constructor that sets up internal variables for maintaining the list of discoverer attributes, callbacks and services.

Discoverer(java.lang.String id, boolean storageFlag)
Constructor that sets up internal variables for maintaining the list of discoverer attributes, callbacks and services.

Discoverer(java.lang.String clientClass, java.lang.String serverClass, int serverPort, java.lang.String encoderClass, java.lang.String decoderClass, boolean storageFlag)
Constructor that sets up internal variables for maintaining the list of discoverer attributes, callbacks, and services and setting up the BaseObject info.

Discoverer(java.lang.String clientClass, java.lang.String serverClass, int serverPort, java.lang.String encoderClass, java.lang.String decoderClass, java.lang.String storageClass)
Constructor that sets up internal variables for maintaining the list of discoverer attributes, callbacks, and services and setting up the BaseObject info.

Method Summary

int	checkSubscribers(Callback callback, ComponentDescription comp) This method allows to send a message to all subscribers whose interests are for the new registered component.
protected DataObject	componentRegistration(DataObject data) This method handles a DISCOVERER_REGISTRATION message.
DataObject	componentSubscription(DataObject dataObject) This method is handling the subscription of a context component that wants to subscribe to be notified of the registration of context components of its interest.
protected DataObject	componentUnregistration(DataObject dataObject) This method is used to unregister a context component from the discoverer.
DataObject	componentUpdate(DataObject dataObject) This method handles the UPDATE_DISCOVERER messages.
DataObject	getDiscovererDescription(DataObject data) ?? TO DO : add errors control This method returns the DataObject replying to the LOOKUP_DISCOVERER message from a component.
java.lang.String	getSearchEngineContent() Returns the content of the search engine
java.lang.String	getType() Returns the type of the object This method should be overridden
void	handleIndependentReply(IndependentCommunication independentCommunication) This method is called after the independentUserRequest has been called.
DataObject	handleQuery(DataObject data) Handles a DISCOVERER_QUUERY message from components and returns a DataObject containing the identification of the response and the first response.
protected Attributes	initAttributes() Sets the attributes for the discoverer: they specify the information the discoverer is storing about the registered context components.
protected Callbacks	initCallbacks() Sets the callbacks for the discoverer
protected Attributes	initConstantAttributes() Sets the constant attributes for the discoverer
protected Services	initServices() Sets the services for the discoverer
static void	main(java.lang.String[] argv) Main method to create a discoverer with location and port specified by command line arguments
protected Attributes	queryGenerator() This abstract method is called when the discoverer wants to get the latest generator info.
protected void	removeComponentDescription(java.lang.Integer componentToRemoveIndex) This method allows to remove a ComponentDescription from the discoverer
protected DataObject	runDiscovererMethod(DataObject dataObject, java.lang.String error) This method should be overriden by inheriting classes to handle other messages.
protected DataObject	runWidgetMethod(DataObject dataObject, java.lang.String error) This method is meant to handle any internal methods that the baseObject doesn't handle.
void	sendLeaseEndNotificationTo(java.util.ArrayList listOfComponents) This method allows to send a lease end notification to each component whose lease ends.
protected boolean	sendLeaseEndNotificationTo(IndependentCommunication comm) This method allows to send the Lease.LEASE_END_NOTIFICATION to a context component.
java.lang.String	subscribersToString() Returns a printable version of the list of discoverer subscribers

Methods inherited from class context.arch.widget.Widget

addSubscriber, canHandle, canHandle, executeService, getAttributeType, getCurrentTime, getNewOffset, getNewOffsetNoDelay, getSubscribersDescription, getUserDescription, getWidgetDescription, isAttribute, isCallback, notify, processCallbackReply, putData, queryAttributes, queryCallbacks, queryConstantAttributes, queryServices, queryWidget, removeSubscriber, retrieveData, runUserMethod, sendToSubscribers, setAttribute, setAttributes, setCallbacks, setConstantAttributes, setId, setNonConstantAttributes, setServices, setSubscribers, store, store, updateWidgetInformation

Methods inherited from class context.arch.BaseObject

activateDisplay, askInterpreter, deactivateDisplay, debugprintln, decodeData, discovererQuery, discovererQuery, discovererRegistration, discovererRegistration, discovererSendSubscription, discovererSubscribe, discovererSubscriptionNotification, discovererUnregistration, discovererUpdate, encodeData, executeAsynchronousWidgetService, executeSynchronousWidgetService, findDiscoverer, findDiscoverer, findDiscoverer, getComponentDescription, getDescription, getHostAddress, getHostName, getId, getId, getLease, getListOfHandlers, getLocationAddress, getPort, getVersion, getVersion, getWidgetAttributes, getWidgetCallbacks, getWidgetConstantAttributes, getWidgetServices, independentUserRequest, leaseEndNotified, pingComponent, pingComponent, pollWidget, println, putDataInWidget, queryVersion, quit, retrieveDataFrom, retrieveDataFrom, returnPing, runComponentMethod, runMethod, serviceResult, setAllDebug, setDiscoverer, setDisplay, setDisplay, setDisplayName, setDisplayTitle, setLease, setLocationAddress, setVersion, subscribeTo, unsubscribeFrom, updateAndPollWidget, userCallback, userRequest, userRequest, userRequest, userRequest

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEBUG

public static final boolean DEBUG

Debug flag. Set to true to see debug messages.

See Also:

Constant Field Values

DEFAULT_PORT

public static final int DEFAULT_PORT

Default port for discoverer to use

See Also:

Constant Field Values

CLASSNAME

public static final java.lang.String CLASSNAME

Classname tag

See Also:

Constant Field Values

LOOKUP_DISCOVERER

public static final java.lang.String LOOKUP_DISCOVERER

Message tag used by components to send a multicast message to lookup a discoverer

See Also:

Constant Field Values

CALLER

public static final java.lang.String CALLER

Tag used in LOOKUP_DISCOVERER to contain the description of the caller component

See Also:

Constant Field Values

CALLER_ID

public static final java.lang.String CALLER_ID

Tag used in LOOKUP_DISCOVERER inside CALLER tags for the component id Also used in LOOKUP_DISCOVERER_REPLY by discoverers

See Also:

Constant Field Values

TYPE

public static final java.lang.String TYPE

Tag used in LOOKUP_DISCOVERER inside CALLER tags for the component type (baseobject(applications), widget, server, interpreter)

See Also:

Constant Field Values

HOSTNAME

public static final java.lang.String HOSTNAME

Tag used in LOOKUP_DISCOVERER inside CALLER tags for the component hostname Also used in LOOKUP_DISCOVERER_REPLY, DISCOVERER_REGISTRATION

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Constant Field Values

HOSTADDRESS

public static final java.lang.String HOSTADDRESS

Tag used in LOOKUP_DISCOVERER inside CALLER tags for the component IP address

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Constant Field Values

PORT

public static final java.lang.String PORT

Tag used in LOOKUP_DISCOVERER inside CALLER tags for the component port Also used in LOOKUP_DISCOVERER_REPLY, DISCOVERER_REGISTRATION

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Constant Field Values

LOOKUP_DISCOVERER_REPLY

public static final java.lang.String LOOKUP_DISCOVERER_REPLY

Message tag used by discoverers to reply to a lookup message

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Constant Field Values

DISCOVERER

public static final java.lang.String DISCOVERER

Tag used in LOOKUP_DISCOVERER_REPLY to contain the discoverer description

See Also:

Constant Field Values

DISCOVERER_TYPE

public static final java.lang.String DISCOVERER_TYPE

See Also:

Constant Field Values

DISCOVERER_ID

public static final java.lang.String DISCOVERER_ID

Tag used in LOOKUP_DISCOVERER_REPLY for the discoverer id Also used in DISCOVERER_REGISTRATION

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Constant Field Values

COMPONENT_ID

public static final java.lang.String COMPONENT_ID

Tag used in DISCOVERER_QUERY_REPLY to give the resulting component id

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Constant Field Values

LOOKUP_DISCOVERER_OK

public static final java.lang.String LOOKUP_DISCOVERER_OK

Message tag used by discoverers to reply to a lookup message

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Constant Field Values

DISCOVERER_REGISTRATION

public static final java.lang.String DISCOVERER_REGISTRATION

Message tag used by components to send to the discoverer their description

See Also:

Constant Field Values

DISCOVERER_UNREGISTRATION

public static final java.lang.String DISCOVERER_UNREGISTRATION

Message tag used by components to unregister from the discoverer

See Also:

Constant Field Values

DISCOVERER_UNREGISTRATION_REPLY

public static final java.lang.String DISCOVERER_UNREGISTRATION_REPLY

Message tag used by the discoverer to reply to a DISCOVERER_UNREGISTRATION message

See Also:

Constant Field Values

DISCOVERER_UPDATE

public static final java.lang.String DISCOVERER_UPDATE

Message tag used by components to send to the discoverer an update

See Also:

Constant Field Values

DISCOVERER_SUBSCRIBE

public static final java.lang.String DISCOVERER_SUBSCRIBE

Message tag used by components to send to the discoverer a subscription

See Also:

Constant Field Values

UPDATE_TYPE

public static final java.lang.String UPDATE_TYPE

Message tag used by components to specify the update's type

See Also:

Constant Field Values

UPDATE_ADD_TYPE

public static final java.lang.String UPDATE_ADD_TYPE

Tag used in UPDATE_TYPE message to specify the method used to update information. Add type is used to add information.

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Constant Field Values

UPDATE_REPLACE_TYPE

public static final java.lang.String UPDATE_REPLACE_TYPE

Tag used in UPDATE_TYPE message to specify the method used to update information Replace type is used to remove old information before adding new one.

See Also:

Constant Field Values

REGISTERER

public static final java.lang.String REGISTERER

Tag used in DISCOVERER_REGISTRATION to contain the description of the component registring

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Constant Field Values

REGISTERER_ID

public static final java.lang.String REGISTERER_ID

Tag used in DISCOVERER_REGISTRATION for the component id

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Constant Field Values

COMPONENT_CLASSNAME

public static final java.lang.String COMPONENT_CLASSNAME

Tag used in DISCOVERER_REGISTRATION for component classname Tag also used in DISCOVERER_QUERY

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Constant Field Values

LOCATION_ADDRESS

public static final java.lang.String LOCATION_ADDRESS

Tag used in DISOCVERER_REGISTRATION for the component location address Tag also used in DISCOVERER_QUERY

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Constant Field Values

CONSTANT_ATTRIBUTE_NAME_VALUES

public static final java.lang.String CONSTANT_ATTRIBUTE_NAME_VALUES

Tag used in DISCOVERER_REGISTRATION to contain the constant attributes of the component Tag also used in DISCOVERER_QUERY This tag is also used in QueryElement to query the discoverer. Then it is used to match the name AND the value of a constant attribute. The match will be successful if the combination of the name&value exists for a component description

See Also:

context.arch.discoverer.query.QueryElement, context.arch.discoverer.query.Query, Constant Field Values

NON_CONSTANT_ATTRIBUTE_NAME_VALUES

public static final java.lang.String NON_CONSTANT_ATTRIBUTE_NAME_VALUES

Tag used in DISCOVERER_REGISTRATION to contain the non constant attributes of the component Tag also used in DISCOVERER_QUERY

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Constant Field Values

CONSTANT_ATTRIBUTE_NAME

public static final java.lang.String CONSTANT_ATTRIBUTE_NAME

Tag used in QueryElement to query the discoverer. It is used to match just the name of a constant attribute

See Also:

context.arch.discoverer.query.QueryElement, context.arch.discoverer.query.Query, Constant Field Values

NON_CONSTANT_ATTRIBUTE_NAME

public static final java.lang.String NON_CONSTANT_ATTRIBUTE_NAME

Tag used in QueryElement to query the discoverer. It is used to match just the name of a non constant attribute

See Also:

context.arch.discoverer.query.QueryElement, context.arch.discoverer.query.Query, Constant Field Values

CONSTANT_ATTRIBUTE_VALUE

public static final java.lang.String CONSTANT_ATTRIBUTE_VALUE

Tag used in QueryElement to query the discoverer. It is used to match just the value of a constant attribute

See Also:

context.arch.discoverer.query.QueryElement, context.arch.discoverer.query.Query, Constant Field Values

SERVER_CONSTANT_ATTRIBUTES

public static final java.lang.String SERVER_CONSTANT_ATTRIBUTES

Tag used in DISCOVERER_REGISTRATION to contain the server constant attributes of the component

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Constant Field Values

SERVER_NON_CONSTANT_ATTRIBUTES

public static final java.lang.String SERVER_NON_CONSTANT_ATTRIBUTES

Tag used in DISCOVERER_REGISTRATION to contain the server non constant attributes of the component

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Constant Field Values

INCOMING_ATTRIBUTE_NAME_VALUES

public static final java.lang.String INCOMING_ATTRIBUTE_NAME_VALUES

Tag used in DISCOVERER_REGISTRATION to contain the incoming attribute name values Tag also used in DISCOVERER_QUERY

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Constant Field Values

OUTGOING_ATTRIBUTE_NAME_VALUES

public static final java.lang.String OUTGOING_ATTRIBUTE_NAME_VALUES

Tag used in DISCOVERER_REGISTRATION to contain the outgoing attribute name values Tag also used in DISCOVERER_QUERY

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Constant Field Values

WIDGET_CALLBACKS

public static final java.lang.String WIDGET_CALLBACKS

Tag used in DISCOVERER_REGISTRATION to contain the widget callback names Tag also used in DISCOVERER_QUERY

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Constant Field Values

SERVER_CALLBACKS

public static final java.lang.String SERVER_CALLBACKS

Tag used in DISCOVERER_REGISTRATION to contain the server callback names

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Constant Field Values

WIDGET_SERVICES

public static final java.lang.String WIDGET_SERVICES

Tag used in DISCOVERER_REGISTRATION to contain the widget service names Tag also used in DISCOVERER_QUERY

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Constant Field Values

SERVER_SERVICES

public static final java.lang.String SERVER_SERVICES

Tag used in DISCOVERER_REGISTRATION to contain the server service names

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Constant Field Values

TEMP_DEST

public static final java.lang.String TEMP_DEST

Tag used by communicationsObject to retrieve the destination address

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Constant Field Values

DISCOVERER_QUERY

public static final java.lang.String DISCOVERER_QUERY

Tag used for query messages to the discoverer

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Constant Field Values

DISCOVERER_QUERY_CONTENT

public static final java.lang.String DISCOVERER_QUERY_CONTENT

Tag used in DISCOVERER_QUERY messages to the discoverer

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Constant Field Values

DISCOVERER_DESCRIPTION_FULL_RESPONSE

public static final java.lang.String DISCOVERER_DESCRIPTION_FULL_RESPONSE

Tag used to determine level of detail of component description in response to subscribers

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Constant Field Values

DISCOVERER_QUERY_REPLY

public static final java.lang.String DISCOVERER_QUERY_REPLY

Tag used for query reply messages to the discoverer

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Constant Field Values

DISCOVERER_QUERY_REPLY_CONTENTS

public static final java.lang.String DISCOVERER_QUERY_REPLY_CONTENTS

Tag used in DISCOVERER_QUERY_REPLY messages to the discoverer

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Constant Field Values

DISCOVERER_QUERY_REPLY_CONTENT

public static final java.lang.String DISCOVERER_QUERY_REPLY_CONTENT

Tag used in DISCOVERER_QUERY_REPLY_CONTENTS messages

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Constant Field Values

DISCOVERER_QUERY_TYPE

public static final java.lang.String DISCOVERER_QUERY_TYPE

Tag used in DISCOVERER_QUERY_CONTENT to indicate the type of query reply

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Constant Field Values

QUERY_ID

public static final java.lang.String QUERY_ID

Tag used in the DISCOVERER_QUERY_REPLY_CONTENT to give the query id

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Constant Field Values

QUERY_ORDER

public static final java.lang.String QUERY_ORDER

Tag used inside the DISCOVERER_QUERY_REPLY_CONTENT to give the order of the response

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Constant Field Values

QUERY_TOTAL_ANSWERS

public static final java.lang.String QUERY_TOTAL_ANSWERS

Tag used inside the DISCOVERER_QUERY_REPLY_CONTENT to give the total number of answers to the query

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Constant Field Values

FIRST_RESULT

public static final java.lang.String FIRST_RESULT

Type of query reply : returns the first element

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Constant Field Values

ALL_RESULTS

public static final java.lang.String ALL_RESULTS

Type of query reply : returns no query id and all results (with a maximum set by

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Constant Field Values

DEFAULT_MAX_RESULTS

public static final int DEFAULT_MAX_RESULTS

Default number of responses sent in replyt to a DISOVERER_QUERY message with a ALL_RESULTS type

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Constant Field Values

NEXT_RESULT

public static final java.lang.String NEXT_RESULT

Type of query reply : returns the next result

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Constant Field Values

MAXIMUM_RESULTS

public static final java.lang.String MAXIMUM_RESULTS

Tag used if DISCOVERER_QUERY to set the maximum number of responses wanted

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Constant Field Values

IGNORE_CASE

public static final java.lang.String IGNORE_CASE

Type of matching for the query

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Constant Field Values

CASE_SENSITIVE

public static final java.lang.String CASE_SENSITIVE

Type of matching for the query

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Constant Field Values

PRIORITY

public static final java.lang.String PRIORITY

Attribute tag used in the DISCOVERER_QUERY_CONTENT

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Constant Field Values

PRIORITY_1

public static final int PRIORITY_1

First or weakest priority for the query element

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Constant Field Values

PRIORITY_2

public static final int PRIORITY_2

Second or middle priority for the query element

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Constant Field Values

PRIORITY_3

public static final int PRIORITY_3

Last or stronger priority for the query element

See Also:

Constant Field Values

APPLICATION

public static final java.lang.String APPLICATION

Component type : for application

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Constant Field Values

WIDGET

public static final java.lang.String WIDGET

Component type : for widget

See Also:

Constant Field Values

SERVER

public static final java.lang.String SERVER

Component type : for servers

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Constant Field Values

INTERPRETER

public static final java.lang.String INTERPRETER

Component type : for interpreter

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Constant Field Values

FIELD_SEPARATOR

public static final java.lang.String FIELD_SEPARATOR

Separator used to separate fields (as for constant attribute name and value)

See Also:

Constant Field Values

ERROR_REGISTRATION_NOT_FOUND

public static final java.lang.String ERROR_REGISTRATION_NOT_FOUND

This tag is used in error object for DISCOVERER_UNREGISTRATION_REPLY messages when the context component that want to be unregistered is not found.

See Also:

Constant Field Values

ERROR_QUERY_NOT_FOUND

public static final java.lang.String ERROR_QUERY_NOT_FOUND

This tag is used when a NEXT_RESULT query is received and the queryId is not reckognized

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Constant Field Values

ERROR_EMPTY_QUERY

public static final java.lang.String ERROR_EMPTY_QUERY

This tag is used when there is no response to the received query

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Constant Field Values

NEW_COMPONENT

public static final java.lang.String NEW_COMPONENT

This tag is the callback name used to notify subscriber of a new component

See Also:

Constant Field Values

mediator

protected DiscovererMediator mediator

Constructor Detail

Discoverer

public Discoverer(java.lang.String clientClass,
                  java.lang.String serverClass,
                  int serverPort,
                  java.lang.String encoderClass,
                  java.lang.String decoderClass,
                  java.lang.String storageClass)

Constructor that sets up internal variables for maintaining the list of discoverer attributes, callbacks, and services and setting up the BaseObject info.

Parameters:

clientClass - Class to use for client communications

serverClass - Class to use for server communications

serverPort - Port to use for server communications

encoderClass - Class to use for communications encoding

decoderClass - Class to use for communications decoding

storageClass - Class to use for storage

See Also:

StorageObject

Discoverer

public Discoverer(java.lang.String clientClass,
                  java.lang.String serverClass,
                  int serverPort,
                  java.lang.String encoderClass,
                  java.lang.String decoderClass,
                  boolean storageFlag)

Constructor that sets up internal variables for maintaining the list of discoverer attributes, callbacks, and services and setting up the BaseObject info. This version takes a boolean to indicate whether the default storage class should be used or whether no storage should be provided.

Parameters:

clientClass - Class to use for client communications

serverClass - Class to use for server communications

serverPort - Port to use for server communications

encoderClass - Class to use for communications encoding

decoderClass - Class to use for communications decoding

storageFlag - Flag to determine whether storage should be used or not

See Also:

StorageObject

Discoverer

public Discoverer(int port,
                  boolean storageFlag)

Constructor that sets up internal variables for maintaining the list of discoverer attributes, callbacks and services. It takes a port number as a parameter to indicate which port to listen for messages/connections, the id to use for the widget, and a flag to indicate whether storage functionality should be turned on or off.

Parameters:

port - Port to listen to for incoming messages

storageFlag - Boolean flag to indicate whether storage should be turned on

Discoverer

public Discoverer(int port)

Constructor that sets up internal variables for maintaining the list of discoverer attributes, callbacks and services. It takes a port number as a parameter to indicate which port to listen for messages/connections.

Parameters:

port - Port to listen to for incoming messages

Discoverer

public Discoverer(java.lang.String id,
                  boolean storageFlag)

Constructor that sets up internal variables for maintaining the list of discoverer attributes, callbacks and services. It takes the id to use for the widget, and a flag to indicate whether storage functionality should be turned on or off.

Parameters:

id - Discoverer id

storageFlag - Boolean flag to indicate whether storage should be turned on

Discoverer

public Discoverer()

Constructor that sets up internal variables for maintaining the list of widget attributes, callbacks and services. It takes the widget id as a parameter

Method Detail

initAttributes

protected Attributes initAttributes()

Sets the attributes for the discoverer: they specify the information the discoverer is storing about the registered context components.

Specified by:

initAttributes in class Widget

Returns:

Attributes The attributes of the discoverer

initConstantAttributes

protected Attributes initConstantAttributes()

Sets the constant attributes for the discoverer

Specified by:

initConstantAttributes in class Widget

Returns:

Attributes The constant attributes of the discoverer

initCallbacks

protected Callbacks initCallbacks()

Sets the callbacks for the discoverer

Specified by:

initCallbacks in class Widget

Returns:

Callbacks The callbacks of the discoverer

initServices

protected Services initServices()

Sets the services for the discoverer

Specified by:

initServices in class Widget

Returns:

Services The services provides by the discoverer

queryGenerator

protected Attributes queryGenerator()

This abstract method is called when the discoverer wants to get the latest generator info.

Specified by:

queryGenerator in class Widget

Returns:

AttributeNameValues containing the latest generator information

runWidgetMethod

protected DataObject runWidgetMethod(DataObject dataObject,
                                     java.lang.String error)

This method is meant to handle any internal methods that the baseObject doesn't handle. In particular, this method handles the common details for query requests, update and query requests, and version requests that each widget should provide. If the method is not one of these queries, then it calls runWidgetMethod which each widget should provide.

Overrides:

runWidgetMethod in class Widget

Parameters:

dataObject - DataObject containing the method to run and parameters

error - Error object

Returns:

DataObject containing the results of the executed method

See Also:

LOOKUP_DISCOVERER, DISCOVERER_REGISTRATION, DISCOVERER_UNREGISTRATION, DISCOVERER_UPDATE, DISCOVERER_QUERY, DISCOVERER_SUBSCRIBE

runDiscovererMethod

protected DataObject runDiscovererMethod(DataObject dataObject,
                                         java.lang.String error)

This method should be overriden by inheriting classes to handle other messages.

Parameters:

dataObject - The data object containing the message

error - The Error object

Returns:

DataObject The result

getDiscovererDescription

public DataObject getDiscovererDescription(DataObject data)

?? TO DO : add errors control This method returns the DataObject replying to the LOOKUP_DISCOVERER message from a component. The reply contains the description of the discoverer and add the id, address and port of the component to reply to.

Parameters:

data - The DataObject containing the identification of the caller component

Returns:

DataObject It contains the LOOKUP_DISCOVERER_REPLY message

See Also:

DiscovererDescription

componentRegistration

protected DataObject componentRegistration(DataObject data)

This method handles a DISCOVERER_REGISTRATION message. It registers a component by storing its description and replies with an error code.

Parameters:

data - The DataObject containing the description on the caller component

Returns:

DataObject An error code

See Also:

ComponentDescription

checkSubscribers

public int checkSubscribers(Callback callback,
                            ComponentDescription comp)

This method allows to send a message to all subscribers whose interests are for the new registered component.

Parameters:

comp - The component newly registered

Returns:

int The number of subscribers a message has been sent to

componentUnregistration

protected DataObject componentUnregistration(DataObject dataObject)

This method is used to unregister a context component from the discoverer. After the unregistration, the context component description will not be referenced in the discoverer.

Parameters:

dataObject - The content of the DISCOVERER_UNREGISTRATION message

Returns:

DataObject The result of the unregistration

See Also:

DISCOVERER_UNREGISTRATION, #ERROR_COMPONENT_NOT_FOUND

removeComponentDescription

protected void removeComponentDescription(java.lang.Integer componentToRemoveIndex)

This method allows to remove a ComponentDescription from the discoverer

Parameters:

componentToRemoveIndex - The index of the component to remove

componentUpdate

public DataObject componentUpdate(DataObject dataObject)

This method handles the UPDATE_DISCOVERER messages. It gets the modified fields and update the component description and returns an error code.

Returns:

DataObject The data containing an error code

See Also:

ComponentDescription

componentSubscription

public DataObject componentSubscription(DataObject dataObject)

This method is handling the subscription of a context component that wants to subscribe to be notified of the registration of context components of its interest. The content of the message is like a query message. The subscriber sends a query containing the description of the components of its interest. The discoverer adds this subscriber, and replies with the corresponding components that have already registered.

Returns:

DataObject contains the reply to the subscriber

handleQuery

public DataObject handleQuery(DataObject data)

Handles a DISCOVERER_QUUERY message from components and returns a DataObject containing the identification of the response and the first response. To complete ...

Parameters:

data - The DataObject containing the query

Returns:

DataObject The first result of the query

See Also:

context.arch.discoverer.Query, context.arch.discoverer.QueryElement, context.arch.discoverer.Response, context.arch.discoverer.ResponseElement, context.arch.discoverer.SearchEngine

getSearchEngineContent

public java.lang.String getSearchEngineContent()

Returns the content of the search engine

Returns:

String The content of the search engine

sendLeaseEndNotificationTo

public void sendLeaseEndNotificationTo(java.util.ArrayList listOfComponents)

This method allows to send a lease end notification to each component whose lease ends. The reply received by the component either renew the lease or confirms it.

Parameters:

listOfComponents - The components index

sendLeaseEndNotificationTo

protected boolean sendLeaseEndNotificationTo(IndependentCommunication comm)

This method allows to send the Lease.LEASE_END_NOTIFICATION to a context component. TO complete to handle the lease_renewal

Returns:

Lease The lease object if the reply from the component is to renew the lease, or null if it confirms the lease end.

handleIndependentReply

public void handleIndependentReply(IndependentCommunication independentCommunication)

This method is called after the independentUserRequest has been called. The thread in charge of the communication sends the results to this method. This method should be overridden by classes that need to handle the responses.

Specified by:

handleIndependentReply in interface MessageHandler

Overrides:

handleIndependentReply in class Widget

Parameters:

independentCommunication - The object sent back by the thread

See Also:

ClientsPool, Client, context.arch.util.RequestObject, DataObject

getType

public java.lang.String getType()

Description copied from class: Widget

Returns the type of the object This method should be overridden

Overrides:

getType in class Widget

Returns:

String

subscribersToString

public java.lang.String subscribersToString()

Returns a printable version of the list of discoverer subscribers

Returns:

String

main

public static void main(java.lang.String[] argv)

Main method to create a discoverer with location and port specified by command line arguments