context.arch.widget
Class Widget

java.lang.Object
  |
  +--context.arch.BaseObject
        |
        +--context.arch.widget.Widget

Direct Known Subclasses:

Server, WContactPresence, WDisplay, WPersonNamePresence2, WPersonPresence, WSoundLevel, WTemperature

public abstract class Widget

extends BaseObject

This class is the basic context widget, with attributes and methods that should apply to all context widgets.

See Also:

BaseObject

Field Summary

protected Attributes	attributes
protected java.util.Hashtable	attributeTypes
protected Callbacks	callbacks
static java.lang.String	CLASS Tag for the class file being used by the widget
protected long	CurrentOffset
static int	DEFAULT_PORT Default port for widgets to use
protected java.lang.String	id
static java.lang.String	PUT_DATA Tag to indicate the widget should accept the given data
static java.lang.String	PUT_DATA_REPLY Tag to indicate the reply to a PUT_DATA message
static java.lang.String	QUERY Tag to indicate the widget should return the latest stored data
static java.lang.String	QUERY_ATTRIBUTES Tag to indicate the widget should return its list of attributes
static java.lang.String	QUERY_ATTRIBUTES_REPLY Tag to indicate the reply to a QUERY_ATTRIBUTES message
static java.lang.String	QUERY_CALLBACKS Tag to indicate the widget should return its list of callbacks
static java.lang.String	QUERY_CALLBACKS_REPLY Tag to indicate the reply to a QUERY_CALLBACKS message
static java.lang.String	QUERY_REPLY Tag to indicate the reply to a QUERY message
static java.lang.String	QUERY_SERVICES Tag to indicate the widget should return its list of services
static java.lang.String	QUERY_SERVICES_REPLY Tag to indicate the reply to a QUERY_SERVICES message
static java.lang.String	QUERY_VERSION Tag to indicate the widget should return its version number
static java.lang.String	QUERY_VERSION_REPLY Tag to indicate the reply to a QUERY_VERSION message
protected Services	services
static java.lang.String	SPACER Constant for the widget spacer
StorageObject	storage Object to keep track of storage
Subscribers	subscribers Object to handle subscriptions to context data
static java.lang.String	TIMESTAMP Tag for the timestamp of widget data
static java.lang.String	UPDATE Tag to indicate an update is being sent
static java.lang.String	UPDATE_AND_QUERY Tag to indicate the widget should get the latest data from the generator and return them
static java.lang.String	UPDATE_AND_QUERY_REPLY Tag to indicate the reply to an UPDATE_AND_QUERY message
static java.lang.String	VERSION Tag for version number.
java.lang.String	VERSION_NUMBER Dummy version number.

Fields inherited from class context.arch.BaseObject

communications, EXIT_OK, handlers, ID, parser, PING, PING_REPLY, serviceHandlers

Constructor Summary

Widget(int port, java.lang.String id)
Constructor that sets up internal variables for maintaining the list of widget attributes, callbacks and services.

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

Widget(java.lang.String id)
Constructor that sets up internal variables for maintaining the list of widget attributes, callbacks and services.

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

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

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

Method Summary

protected DataObject	addSubscriber(DataObject sub, java.lang.String error) This method adds a subscriber to this object.
protected boolean	canHandle(AttributeFunctions atts, Conditions conds) This method checks the list of attributes and conditions to ensure that the widget contains these attributes.
protected boolean	canHandle(AttributeNameValues atts) This method checks the list of attributes (in an AttributeNameValues object) to ensure that the widget contains these attributes.
protected boolean	canHandle(Attributes attributes) This method checks the list of attributes to ensure that the widget contains these attributes.
protected boolean	canHandle(Attributes atts, Conditions conds) This method checks the list of attributes and conditions to ensure that the widget contains these attributes.
protected DataObject	executeService(DataObject request, java.lang.String error) This method attempts to execute a widget service.
protected java.lang.String	getAttributeType(java.lang.String name) Returns the attribute value with the given name
protected java.lang.Long	getCurrentTime() This method returns the current time to use as a timestamp
protected void	getNewOffset() This method creates a thread that retrieves a global time clock and determines the offset between the local clock and the global clock.
protected long	getNewOffsetNoDelay() This method retrieves the offset between the local clock and a global clock with no delay.
protected boolean	isAttribute(java.lang.String name) Checks if the given attribute is an attribute of this widget
protected boolean	isCallback(java.lang.String name) Checks if the given callback is an callback of this widget
void	notify(java.lang.String event, java.lang.Object data) This is an empty method that should be overridden by objects that subclass from this class.
protected void	processCallbackReply(DataObject result, Subscriber sub) This method should be overriden to process the results of subscription callbacks.
protected DataObject	putData(DataObject data, java.lang.String error) This method puts context data in a widget.
protected DataObject	queryAttributes(DataObject query, java.lang.String error) This method queries the attributes of a widget.
protected DataObject	queryCallbacks(DataObject query, java.lang.String error) This method queries the callbacks of a widget.
protected abstract AttributeNameValues	queryGenerator() This abstract method is called when the widget wants to get the latest generator info.
protected DataObject	queryServices(DataObject query, java.lang.String error) This method queries the services of a widget.
protected DataObject	queryWidget(DataObject query, boolean update, java.lang.String error) This method runs a query on a widget, asking for either it's latest acquired data (QUERY) or asking for the widget to acquire and return new data (UPDATE_AND_QUERY)
protected DataObject	removeSubscriber(DataObject sub, java.lang.String error) This method removes a subscriber to this object.
protected DataObject	retrieveData(DataObject data, java.lang.String error) This method retrieves data from the widget's storage.
DataObject	runUserMethod(DataObject data) This method is meant to handle any internal methods that the baseObject doesn't handle.
protected DataObject	runWidgetMethod(DataObject data, java.lang.String error) This is an empty method that should be overridden by objects that subclass from this class.
protected void	sendToSubscribers(java.lang.String callback, AttributeNameValues atts) This method should be called to send data to subscribers when a context widget's callback is triggered.
protected void	setAttribute(java.lang.String name, java.lang.String type) Sets an attribute
protected abstract Attributes	setAttributes() Sets the attributes for the widget
protected abstract Callbacks	setCallbacks() Sets the callbacks for the widget
protected abstract Services	setServices() Sets the services for the widget
protected void	store(AttributeNameValues data) This stub method stores the data in the given AttributeNameValues object
protected void	store(DataObject data) This stub method stores the data in the given DataObject
protected void	updateWidgetInformation() This method is called when a remote component sends an UPDATE_AND_QUERY message.

Methods inherited from class context.arch.BaseObject

askInterpreter, decodeData, encodeData, executeAsynchronousWidgetService, executeSynchronousWidgetService, getHostAddress, getId, getVersion, getVersion, getWidgetAttributes, getWidgetCallbacks, getWidgetServices, main, pingComponent, pollWidget, putDataInWidget, queryVersion, quit, retrieveDataFrom, retrieveDataFrom, retrieveDataFrom, retrieveDataFrom, retrieveDataFrom, retrieveDataFrom, retrieveDataFrom, returnPing, runComponentMethod, runMethod, serviceResult, setId, setVersion, subscribeTo, subscribeTo, subscribeTo, subscribeTo, unsubscribeFrom, updateAndPollWidget, userCallback, userRequest, userRequest, userRequest

Methods inherited from class java.lang.Object

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

Field Detail

CLASS

public static final java.lang.String CLASS

Tag for the class file being used by the widget

VERSION_NUMBER

public java.lang.String VERSION_NUMBER

Dummy version number. Subclasses should override this value.

DEFAULT_PORT

public static final int DEFAULT_PORT

Default port for widgets to use

VERSION

public static final java.lang.String VERSION

Tag for version number.

TIMESTAMP

public static final java.lang.String TIMESTAMP

Tag for the timestamp of widget data

QUERY

public static final java.lang.String QUERY

Tag to indicate the widget should return the latest stored data

QUERY_REPLY

public static final java.lang.String QUERY_REPLY

Tag to indicate the reply to a QUERY message

UPDATE_AND_QUERY

public static final java.lang.String UPDATE_AND_QUERY

Tag to indicate the widget should get the latest data from the generator and return them

UPDATE_AND_QUERY_REPLY

public static final java.lang.String UPDATE_AND_QUERY_REPLY

Tag to indicate the reply to an UPDATE_AND_QUERY message

QUERY_ATTRIBUTES

public static final java.lang.String QUERY_ATTRIBUTES

Tag to indicate the widget should return its list of attributes

QUERY_ATTRIBUTES_REPLY

public static final java.lang.String QUERY_ATTRIBUTES_REPLY

Tag to indicate the reply to a QUERY_ATTRIBUTES message

QUERY_CALLBACKS

public static final java.lang.String QUERY_CALLBACKS

Tag to indicate the widget should return its list of callbacks

QUERY_CALLBACKS_REPLY

public static final java.lang.String QUERY_CALLBACKS_REPLY

Tag to indicate the reply to a QUERY_CALLBACKS message

QUERY_SERVICES

public static final java.lang.String QUERY_SERVICES

Tag to indicate the widget should return its list of services

QUERY_SERVICES_REPLY

public static final java.lang.String QUERY_SERVICES_REPLY

Tag to indicate the reply to a QUERY_SERVICES message

QUERY_VERSION

public static final java.lang.String QUERY_VERSION

Tag to indicate the widget should return its version number

QUERY_VERSION_REPLY

public static final java.lang.String QUERY_VERSION_REPLY

Tag to indicate the reply to a QUERY_VERSION message

PUT_DATA

public static final java.lang.String PUT_DATA

Tag to indicate the widget should accept the given data

PUT_DATA_REPLY

public static final java.lang.String PUT_DATA_REPLY

Tag to indicate the reply to a PUT_DATA message

UPDATE

public static final java.lang.String UPDATE

Tag to indicate an update is being sent

SPACER

public static final java.lang.String SPACER

Constant for the widget spacer

id

protected java.lang.String id

attributes

protected Attributes attributes

attributeTypes

protected java.util.Hashtable attributeTypes

callbacks

protected Callbacks callbacks

services

protected Services services

CurrentOffset

protected long CurrentOffset

subscribers

public Subscribers subscribers

Object to handle subscriptions to context data

See Also:

Subscribers, Subscriber

storage

public StorageObject storage

Object to keep track of storage

See Also:

StorageObject

Constructor Detail

Widget

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

Constructor that sets up internal variables for maintaining the list of widget 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

id - String to use for widget id and persistent storage

See Also:

StorageObject

Widget

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

Constructor that sets up internal variables for maintaining the list of widget 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

id - String to use for widget id and persistent storage

See Also:

StorageObject

Widget

public Widget(int port,
              java.lang.String id,
              boolean storageFlag)

Constructor that sets up internal variables for maintaining the list of widget 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

id - Widget id

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

Widget

public Widget(int port,
              java.lang.String id)

Constructor that sets up internal variables for maintaining the list of widget 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

id - Widget id

Widget

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

Constructor that sets up internal variables for maintaining the list of widget 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 - Widget id

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

Widget

public Widget(java.lang.String id)

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

Parameters:

id - ID of the widget

Method Detail

setAttributes

protected abstract Attributes setAttributes()

Sets the attributes for the widget

setCallbacks

protected abstract Callbacks setCallbacks()

Sets the callbacks for the widget

setServices

protected abstract Services setServices()

Sets the services for the widget

getAttributeType

protected java.lang.String getAttributeType(java.lang.String name)

Returns the attribute value with the given name

Parameters:

name - Name of the attribute to get

setAttribute

protected void setAttribute(java.lang.String name,
                            java.lang.String type)

Sets an attribute

Parameters:

name - Name of the attribute to set

type - Type of the attribute

isAttribute

protected boolean isAttribute(java.lang.String name)

Checks if the given attribute is an attribute of this widget

Parameters:

name - Name of the attribute to check

isCallback

protected boolean isCallback(java.lang.String name)

Checks if the given callback is an callback of this widget

Parameters:

name - Name of the callback to check

notify

public void notify(java.lang.String event,
                   java.lang.Object data)

This is an empty method that should be overridden by objects that subclass from this class. It is intended to be called by generator objects when new data has arrived for the purpose of notifying the widget.

Parameters:

event - Name of the event occurring

data - Object containing the relevant data

updateWidgetInformation

protected void updateWidgetInformation()

This method is called when a remote component sends an UPDATE_AND_QUERY message. It calls the widget's queryGenerator method to get the latest generator info, and then stores it.

queryGenerator

protected abstract AttributeNameValues queryGenerator()

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

Returns:

AttributeNameValues containing the latest generator information

runWidgetMethod

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

This is an empty method that should be overridden by objects that subclass from this class. It is called when another component tries to run a method on the widget, but it's not a query.

Parameters:

data - DataObject containing the data for the method

error - String containing the incoming error value

Returns:

DataObject containing the method results

runUserMethod

public DataObject runUserMethod(DataObject data)

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:

runUserMethod in class BaseObject

Parameters:

data - DataObject containing the method to run and parameters

Returns:

DataObject containing the results of running the method

See Also:

QUERY, QUERY_VERSION, UPDATE_AND_QUERY

putData

protected DataObject putData(DataObject data,
                             java.lang.String error)

This method puts context data in a widget. It is expected that widgets will get data from a generator. But for some widgets, the generator will not use the context toolkit directly, but may use a web CGI script, for example. For this case, the widget provides this method to collect the data and makes it available to subscribers and for retrieval.

Parameters:

data - DataObject containing the context data to write

error - String containing the incoming error value

Returns:

DataObject containing the results of writing the data

queryCallbacks

protected DataObject queryCallbacks(DataObject query,
                                    java.lang.String error)

This method queries the callbacks of a widget.

Parameters:

query - DataObject containing the query

error - String containing the incoming error value

Returns:

DataObject containing the results of the query

queryAttributes

protected DataObject queryAttributes(DataObject query,
                                     java.lang.String error)

This method queries the attributes of a widget.

Parameters:

query - DataObject containing the query

error - String containing the incoming error value

Returns:

DataObject containing the results of the query

queryServices

protected DataObject queryServices(DataObject query,
                                   java.lang.String error)

This method queries the services of a widget.

Parameters:

query - DataObject containing the query

error - String containing the incoming error value

Returns:

DataObject containing the results of the query

queryWidget

protected DataObject queryWidget(DataObject query,
                                 boolean update,
                                 java.lang.String error)

This method runs a query on a widget, asking for either it's latest acquired data (QUERY) or asking for the widget to acquire and return new data (UPDATE_AND_QUERY)

Parameters:

query - DataObject containing the query request

update - Whether or not to acquire new data

error - String containing the incoming error value

Returns:

DataObject containing the reply to the query

canHandle

protected boolean canHandle(Attributes attributes)

This method checks the list of attributes to ensure that the widget contains these attributes.

Parameters:

attributes - Attributes object containing attributes to check

Returns:

whether the list of attributes is valid

canHandle

protected boolean canHandle(Attributes atts,
                            Conditions conds)

This method checks the list of attributes and conditions to ensure that the widget contains these attributes.

Parameters:

atts - List of attributes to check

conds - List of Conditions to check

Returns:

whether the list of attributes and conditions is valid

canHandle

protected boolean canHandle(AttributeFunctions atts,
                            Conditions conds)

This method checks the list of attributes and conditions to ensure that the widget contains these attributes.

Parameters:

atts - List of attributes to check

conds - List of Conditions to check

Returns:

whether the list of attributes and conditions is valid

canHandle

protected boolean canHandle(AttributeNameValues atts)

This method checks the list of attributes (in an AttributeNameValues object) to ensure that the widget contains these attributes.

Parameters:

atts - List of attributes to check

Returns:

whether the list of attributes and conditions is valid

executeService

protected DataObject executeService(DataObject request,
                                    java.lang.String error)

This method attempts to execute a widget service.

Parameters:

request - DataObject containing the service request

error - String containing the incoming error value

Returns:

DataObject containing the results of the service request

sendToSubscribers

protected void sendToSubscribers(java.lang.String callback,
                                 AttributeNameValues atts)

This method should be called to send data to subscribers when a context widget's callback is triggered. It sends data only to those subscribers that have subscribed to the specified callback.

Parameters:

callbackTag - Context widget callback that was triggered

atts - AttributeNameValues to send to subscribers

data - DataObject version of atts

See Also:

BaseObject.userRequest(DataObject, String, String, int), Subscribers

processCallbackReply

protected void processCallbackReply(DataObject result,
                                    Subscriber sub)

This method should be overriden to process the results of subscription callbacks.

Parameters:

result - DataObject containing the result

sub - Subscriber that returned this reply

addSubscriber

protected DataObject addSubscriber(DataObject sub,
                                   java.lang.String error)

This method adds a subscriber to this object. It calls Subscribers.addSubscriber() if it can add the subscriber. It returns a DataObject containing the reply information, including any error information.

Parameters:

sub - DataObject containing the subscription information

error - String containing the incoming error value

Returns:

DataObject with the reply to the subscription request

See Also:

Subscribers.addSubscriber(String,String,int,String,String,Conditions,Attributes)

removeSubscriber

protected DataObject removeSubscriber(DataObject sub,
                                      java.lang.String error)

This method removes a subscriber to this object. It calls Subscribers.removeSubscriber() if it can remove the subscriber. It returns a DataObject containing the reply information, including any error information.

Parameters:

sub - DataObject containing the subscription information

error - String containing the incoming error value

Returns:

DataObject with the reply to the subscription request

See Also:

Subscribers.removeSubscriber(String, String, String, String, String)

retrieveData

protected DataObject retrieveData(DataObject data,
                                  java.lang.String error)

This method retrieves data from the widget's storage. It returns a DataObject containing the retrieved data information, including any error information.

Parameters:

data - DataObject containing the subscription information

error - String containing the incoming error value

Returns:

DataObject with the reply to the subscription request

store

protected void store(DataObject data)

This stub method stores the data in the given DataObject

Parameters:

data - Data to store

See Also:

StorageObject.store(DataObject)

store

protected void store(AttributeNameValues data)

This stub method stores the data in the given AttributeNameValues object

Parameters:

data - Data to store

See Also:

StorageObject.store(AttributeNameValues)

getNewOffset

protected void getNewOffset()

This method creates a thread that retrieves a global time clock and determines the offset between the local clock and the global clock. It checks this

Returns:

the offset between the global and local clocks

See Also:

OffsetThread

getNewOffsetNoDelay

protected long getNewOffsetNoDelay()

This method retrieves the offset between the local clock and a global clock with no delay.

Returns:

the offset between the global and local clocks

See Also:

OffsetThread

getCurrentTime

protected java.lang.Long getCurrentTime()

This method returns the current time to use as a timestamp

Returns:

the current time, corrected using a global clock offset