context.arch
Class BaseObject

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

Direct Known Subclasses:

InOutBoardServer, Interpreter, Widget

public class BaseObject

extends java.lang.Object

implements MessageHandler, CommunicationsHandler

This class is the base object for the context-aware infrastructure. It is able to poll and subscribe to other components and can be polled and subscribed to by other components. It also can generate and handle RPC-style requests. It consists of 2 main objects, the CommunicationsObject and ParserObject. It also maintains a list of subscribers and a list of handlers.

See Also:

CommunicationsObject, ParserObject, Handler

Field Summary

CommunicationsObject	communications Object to handle communications between components
static int	EXIT_OK Indicates that the exit condition is normal
Handlers	handlers Object to keep track of context widget handlers
static java.lang.String	ID Tag for id of this component
ParserObject	parser Object to handle the encoding and decoding of communications
static java.lang.String	PING Tag for a ping
static java.lang.String	PING_REPLY Tag for a ping reply
AsyncServiceHandlers	serviceHandlers Object to keep track of asynchronous service handlers

Constructor Summary

BaseObject()
Basic constructor that creates a CommunicationsObject, ParserObject and Handlers object.

BaseObject(int port)
Constructor that just creates a CommunicationsObject with the given port and ParserObject.

BaseObject(int port, java.lang.String protocol)
Constructor that just creates a CommunicationsObject with the given port and protocol handler class, and ParserObject.

BaseObject(java.lang.String protocol)
Constructor that just creates a CommunicationsObject with the given protocol handler class, and a ParserObject.

BaseObject(java.lang.String clientClass, java.lang.String serverClass, int serverPort, java.lang.String encoderClass, java.lang.String decoderClass)
Basic constructor that creates a CommunicationsObject with the given port and protocol, and creates a ParserObject with the given encoder and decoder.

Method Summary

DataObject	askInterpreter(java.lang.String remoteHost, int remotePort, java.lang.String remoteId, AttributeNameValues data) This method asks an interpreter to interpret some data.
DataObject	decodeData(java.io.Reader commData) Stub method that decodes the given string using ParserObject
java.lang.String	encodeData(DataObject commData) Stub method that encodes the given string using ParserObject
DataObject	executeAsynchronousWidgetService(AsyncServiceHandler handler, java.lang.String serviceHost, int servicePort, java.lang.String serviceId, java.lang.String service, java.lang.String function, AttributeNameValues input, java.lang.String requestTag) This method requests that a widget execute an asynchronous service
DataObject	executeSynchronousWidgetService(java.l ang.String remoteHost, int remotePort, java.lang.String remoteId, java.lang.String service, java.lang.String function, AttributeNameValues input) This method requests that a widget execute a synchronous service
java.lang.String	getHostAddress() This method gets the address of the machine this component is running on.
java.lang.String	getId() This method returns the id of the class that subclass this object, for use in sending messages.
java.lang.String	getVersion() This method returns the version number of this object.
DataObject	getVersion(java.lang.String remoteHost, int remotePort, java.lang.String remoteId) This method gets the version of the given component (server, widget, interpreter).
DataObject	getWidgetAttributes(java.lang.String widgetHost, int widgetPort, java.lang.String widgetId) This method gets the attributes of the given widget
DataObject	getWidgetCallbacks(java.lang.String widgetHost, int widgetPort, java.lang.String widgetId) This method gets the callbacks of the given widget
DataObject	getWidgetServices(java.lang.String widgetHost, int widgetPort, java.lang.String widgetId) This method gets the services of the given widget
static void	main(java.lang.String[] argv) Temporary main method to test the BaseObject class
DataObject	pingComponent(java.lang.String remoteHost, int remotePort, java.lang.String remoteId) This method pings a component (widget,server, or interpreter) to make sure that it is functioning ok.
DataObject	pollWidget(java.lang.String widgetHost, int widgetPort, java.lang.String widgetId, Attributes attributes) This method allows a component to poll a remote widget for its attribute values.
DataObject	putDataInWidget(java.lang.String widgetHost, int widgetPort, java.lang.String widgetId, java.lang.String callback, AttributeNameValues attributes) This method allows a component to put context data in a remote widget.
DataObject	queryVersion(DataObject query) This method returns the version number of this component.
void	quit() This method should be called when the object is going to exit under normal conditions.
DataObject	retrieveDataFrom(java.lang.String remoteHost, int remotePort, java.lang.String remoteId) This method returns a vector containing AttributeNameValues objects for all the the data.
DataObject	retrieveDataFrom(java.lang.String remoteHost, int remotePort, java.lang.String remoteId, AttributeFunctions attributes) This method returns a vector containing AttributeNameValues objects for all the the data of the given attributes.
DataObject	retrieveDataFrom(java.lang.String remoteHost , int remotePort, java.lang.String remoteId, AttributeFunctions attributes, java.lang.String attribute, int compare, java.lang.Object value) This method returns a vector containing AttributeNameValues objects for all the the data of the given attributes and a single condition.
DataObject	retrieveDataFrom(java.lang.String remoteHost, int remotePort, java.lang.String remoteId, Retrieval retrieval) This method allows a component to retrieve data from other components.
DataObject	retrieveDataFrom(java.lang.String remoteHost, int remotePort, java.lang.String remoteId, java.lang.String attribute) This method returns a vector containing AttributeNameValues objects for all the the data of a given attribute.
DataObject	retrieveDataFrom(java.lang.String remoteHost, int remotePort, java.lang.String remoteId, java.lang.String attribute, int compare, java.lang.Object value) This method returns a vector containing AttributeNameValues objects for all the the data and a single condition.
DataObject	retrieveDataFrom(java.lang.String remoteHost, int remotePort, java.lang.String remoteId, java.lang.String myId, Retrieval retrieval) This method allows a component to retrieve data from other components.
DataObject	returnPing(DataObject ping) This method returns an error message as an answer to a ping.
DataObject	runComponentMethod(java.lang.String& nbsp;remoteHost, int remotePort, java.lang.String remoteId, java.lang.String methodName, AttributeNameValues parameters, Attributes attributes) This method asks an component to run some non-standard method.
DataObject	runMethod(java.lang.String methodType, DataObject data) This method handles both the system-defined, callbacks and user-defined RPCs.
DataObject	runUserMethod(DataObject data) This is an empty method that should be overridden by the object that extends this class.
DataObject	serviceResult(DataObject result) This method handles the results of an asynchronous service request.
void	setId(java.lang.String id) This method sets the id of classes that subclass this object, for use in sending messages.
void	setVersion(java.lang.String version) This method sets the version number of this object.
Error	subscribeTo(Handler handler, int port, java.lang.String subid, java.lang.String remoteHost, int remotePort, java.lang.String remoteId, java.lang.String callback, java.lang.String tag This method allows a component to subscribe to changes in other components.
Error	subscribeTo(Handler handler, int port, java.lang.String subid, java.lang.String remoteHost, int remotePort, java.lang.String remoteId, java.lang.String callback, java.lang.String tag, Attributes attributes) This method allows a component to subscribe to changes in other components.
Error	subscribeTo(Handler handler, int port, java.lang.String subid, java.lang.String remoteHost, int remotePort, java.lang.String remoteId, java.lang.String callback, java.lang.String tag, Conditions conditions) This method allows a component to subscribe to changes in other components.
Error	subscribeTo(Handler handler, int port, java.lang.String subid, java.lang.String remoteHost, int remotePort, java.lang.String remoteId, java.lang.String callback, java.lang.String tag, Conditions conditions, Attributes attributes) This method allows a component to subscribe to changes in other components.
Error	unsubscribeFrom( Handler handler, java.lang.String remoteHost, int remotePort, java.lang.String remoteId, Subscriber subscriber) This method allows a component to unsubscribe from another component.
DataObject	updateAndPollWidget(java.lang.String widgetHost, int widgetPort, java.lang.String widgetId, Attributes attributes) This method allows a component to force a remote widget to update its data and return it.
DataObject	userCallback(DataObject data) This method is called when a callback message is received.
DataObject	userRequest(DataObject data, java.lang.String tag) Method that submits a user request for polling/subscription.
DataObject	userRequest(DataObject data, java.lang.String tag, java.lang.String server) Method that submits a user request for polling/subscription.
DataObject	userRequest(DataObject data, java.lang.String tag, java.lang.String server, int port) Method that submits a user request for polling/subscription.

Methods inherited from class java.lang.Object

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

Field Detail

EXIT_OK

public static final int EXIT_OK

Indicates that the exit condition is normal

ID

public static final java.lang.String ID

Tag for id of this component

PING

public static final java.lang.String PING

Tag for a ping

PING_REPLY

public static final java.lang.String PING_REPLY

Tag for a ping reply

communications

public CommunicationsObject communications

Object to handle communications between components

See Also:

CommunicationsObject

parser

public ParserObject parser

Object to handle the encoding and decoding of communications

See Also:

ParserObject

handlers

public Handlers handlers

Object to keep track of context widget handlers

See Also:

Handlers, Handler

serviceHandlers

public AsyncServiceHandlers serviceHandlers

Object to keep track of asynchronous service handlers

See Also:

AsyncServiceHandlers, AsyncServiceHandler

Constructor Detail

BaseObject

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

Basic constructor that creates a CommunicationsObject with the given port and protocol, and creates a ParserObject with the given encoder and decoder. It also creates a Handlers object to keep track of context widget handlers.

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

See Also:

CommunicationsObject, CommunicationsObject.start(), ParserObject, Handlers

BaseObject

public BaseObject()

Basic constructor that creates a CommunicationsObject, ParserObject and Handlers object.

See Also:

CommunicationsObject, CommunicationsObject.start(), ParserObject, Handlers

BaseObject

public BaseObject(int port)

Constructor that just creates a CommunicationsObject with the given port and ParserObject. It also creates a Handlers object to keep track of context widget handlers.

Parameters:

port - Port number to communicate on

See Also:

CommunicationsObject, CommunicationsObject.start(), ParserObject, Handlers

BaseObject

public BaseObject(java.lang.String protocol)

Constructor that just creates a CommunicationsObject with the given protocol handler class, and a ParserObject. It also creates a Handlers object to keep track of context widget handlers.

Parameters:

protocol - Protocol handler class to communicate with

See Also:

CommunicationsObject, CommunicationsObject.start(), ParserObject, Handlers

BaseObject

public BaseObject(int port,
                  java.lang.String protocol)

Constructor that just creates a CommunicationsObject with the given port and protocol handler class, and ParserObject. It also creates a Handlers object to keep track of context widget handlers.

Parameters:

port - Port number to communicate on

protocol - Protocol handler class name to communicate with

See Also:

Communications Object, CommunicationsObject.start(), ParserObject, Handlers

Method Detail

decodeData

public DataObject decodeData(java.io.Reader commData)
                      throws DecodeException,
                             InvalidDecoderException

Stub method that decodes the given string using ParserObject

Specified by:

decodeData in interface MessageHandler

Parameters:

commData - String to be decoded

Returns:

the decoded data

Throws:

DecodeException - thrown if the parser can't decode the given string

InvalidDecoderException - thrown if the parser can't create the necessary decoder

See Also:

ParserObject.decodeData(java.io.Reader)

encodeData

public java.lang.String encodeData(DataObject commData)
                            throws EncodeException,
                                   InvalidEncoderException

Stub method that encodes the given string using ParserObject

Specified by:

encodeData in interface MessageHandler

Parameters:

commData - String to be decoded

Returns:

the encoded data

Throws:

EncodeException - thrown if the parser can't encode the given string

InvalidEncoderException - thrown if the parser can't create the necessary encoder

See Also:

ParserObject.encodeData(context.arch.comm.DataObject)

userRequest

public DataObject userRequest(DataObject data,
                              java.lang.String tag)
                       throws EncodeException,
                              InvalidProtocolException,
                              ProtocolException,
                              DecodeException,
                              InvalidDecoderException,
                              InvalidEncoderException

Method that submits a user request for polling/subscription. The request is in the form of a DataObject. It is encoded, sent out and the reply is decoded, if necessary, and returned.

Specified by:

userRequest in interface CommunicationsH andler

Parameters:

data - DataObject that contains the request

tag - local alias for callback

Returns:

DataObject containing the reply to the request

Throws:

EncodeException - when the encoding can't be completed successfully

DecodeException - when the decoding can't be completed successful ly

InvalidEncoderException - when the encoder can't be created

InvalidDecoderException - when the decoder can't be created

ProtocolException - when the request can't be sent successfully

InvalidProtocolE xception - when the request can't be sent successfully due to invalid protocol use

userRequest

public DataObject userRequest(DataObject data,
                              java.lang.String alias,
                              java.lang.String server)
                       throws EncodeException,
                              InvalidProtocolException,
                              ProtocolException,
                              DecodeException,
                              InvalidDecoderException,
                              InvalidEncoderException

Method that submits a user request for polling/subscription. The request is in the form of a DataObject. It is encoded, sent out and the reply is decoded, if necessary, and returned.

Specified by:

userRequest in interface CommunicationsHandler

Parameters:

data - DataObject that contains the request

tag - local alias for callback

server - Hostname of the component the request is being sent to

Returns:

DataO bject containing the reply to the request

Throws:

EncodeException - when the encoding can't be completed successfully

DecodeException - when the decoding can't be completed successfully

InvalidEncoderException - when the encoder can't be created

InvalidDecoderException - when the decoder can't be created

ProtocolException - when the request can't be sent successfully

InvalidProtocolException - when the request can't be sent successfully due to invalid protocol use

userRequest

public DataObject userRequest(DataObject data,
                              java.lang.String tag,
                              java.lang.String server,
                              int port)
                       throws EncodeException,
                              ProtocolException,
                              InvalidProtocolException,
                              DecodeException,
                              InvalidDecoderException,
                              InvalidEncoderException

Method that submits a user request for polling/subscription. The request is in the form of a DataObject. It is encoded, sent out and the reply is decoded, if necessary, and returned.

Specified by:

userRequest in interface CommunicationsHandler

Parameters:

data - DataObject that contains the request

tag - local alias for callback

server - Hostname of the component the request is being sent to

port - Port number of the component the request is being sent to

Returns:

DataObject containing the reply to the request

Throws:

EncodeException - when the encoding can't b e completed successfully

DecodeException - when the decoding can't be completed successfully

InvalidEncoderEx ception - when the encoder can't be created

InvalidDecoderException - when the decoder can't be created

ProtocolException - when the request can't be sent successfully

InvalidProtocolException - when the request can't be sent successfully due to invalid protocol use

subscribeTo

public Error subscribeTo(Handler handler,
                         int port,
                         java.lang.String subid,
                         java.lang.String remoteHost,
                         int remotePort,
                         java.lang.String remoteId,
                         java.lang.String callback,
                         java.lang.String tag)

This method allows a component to subscribe to changes in other components. The subscription includes the handler that will handle the callbacks, the subscriber's hostname and port, the subscription id, the remote component's hostname, port, and id, the remote component's callback, and the name of the subscriber's method that will handle the callback.

Parameters:

handler - Object that handles context widget callbacks

port - Port number the subscriber receives communications on

subId - Subscription id

remoteHost - Hostname of the context widget being subscribed to

remotePort - Port number the context widget receives communication on

remoteId - Id of the context widget being subscribed to

callback - Callback defined by the context wi dget

tag - Local alias for callback

Returns:

Error to indicate success of subscription

See Also:

Handler s, Handlers.addHandler(context.arch.handler.HandlerInfo), userRequest(context.arch.comm.DataObject, String, String, int)

subscribeTo

public Error subscribeTo(Handler handler,
                         int port,
                         java.lang.String subid,
                         java.lang.String remoteHost,
                         int remotePort,
                         java.lang.String remoteId,
                         java.lang.String callback,
                         java.lang.String tag,
                         Conditions conditions)

This method allows a component to subscribe to changes in other components. The subscription includes the handler that will handle the callbacks, the subscriber's hostname and port, the subscription id, the remote component's hostname, port, and id, the remote component's callback, and the name of the subscriber's method that will handle the callback.

Parameters:

handler - Object that handles context widget callbacks

port - Port number the subscriber receives communications on

subId - Subscription id

remoteHost - Hostname of the context widget being subscribed to

remotePort - Port number the context widget receives communication on

remoteId - Id of the context widget being subscribed to

callback - Callback defined by the context wi dget

tag - Name of the subscriber method that handles the callback being subscribed to

conditions - Any conditions to put on the subscription

Returns:

Error to indicate success of subscription

See Also: < /B>

Handlers, Handlers.addHandler(context.arch.handler.HandlerInfo), userRequest(context.arch.comm.DataObject, String, String, int)

subscribeTo

public Error subscribeTo(Handler handler,
                         int port,
                         java.lang.String subid,
                         java.lang.String remoteHost,
                         int remotePort,
                         java.lang.String remoteId,
                         java.lang.String callback,
                         java.lang.String tag,
                         Attributes attributes)

This method allows a component to subscribe to changes in other components. The subscription includes the handler that will handle the callbacks, the subscriber's hostname and port, the subscription id, the remote component's hostname, port, and id, the remote component's callback, and the name of the subscriber's method that will handle the callback.

Parameters:

handler - Object that handles context widget callbacks

port - Port number the subscriber receives communications on

subId - Subscription id

remoteHost - Hostname of the context widget being subscribed to

remotePort - Port number the context widget receives communication on

remoteId - Id of the context widget being subscribed to

callback - Callback defined by the context wi dget

tag - Name of the subscriber method that handles the callback being subscribed to

attributes - Attributes to return to the subscriber

Returns:

Error to indicate success of subscription

See Also:

Handlers, Handlers.addHandler(context.arch.handler.HandlerInfo), userRequest(context.arch.comm.DataObject, String, String, int)

subscribeTo

public Error subscribeTo(Handler handler,
                         int port,
                         java.lang.String subid,
                         java.lang.String remoteHost,
                         int remotePort,
                         java.lang.String remoteId,
                         java.lang.String callback,
                         java.lang.String tag,
                         Conditions conditions,
                         Attributes attributes)

This method allows a component to subscribe to changes in other components. The subscription includes the handler that will handle the callbacks, the subscriber's hostname and port, the subscription id, the remote component's hostname, port, and id, the remote component's callback, and the name of the subscriber's method that will handle the callback.

Parameters:

handler - Object that handles context widget callbacks

port - Port number the subscriber receives communications on

subId - Subscription id

remoteHost - Hostname of the context widget being subscribed to

remotePort - Port number the context widget receives communication on

remoteId - Id of the context widget being subscribed to

callback - Callback defined by the context wi dget

tag - local alias for callback

conditions - Any conditions to put on the subscription

attributes - Attributes to return to the subscriber

Returns :

Error to indicate success of subscription

See Also:

Handlers, Handlers.addHandler(context.arch.handler.HandlerInfo), userRequest(context.arch.comm.DataObject, String, String, int)

unsubscribeFrom

public Error unsubscribeFrom(Handler handler,
                             java.lang.String remoteHost,
                             int remotePort,
                             java.lang.String remoteId,
                             Subscriber subscriber)

This method allows a component to unsubscribe from another component.

Parameters:

handler - Object that handles context widget callbacks

remoteHost - Hostname of the widget being unsubscribed from

remotePort - Port number of the widget being unsubscribed from

remoteId - Id of the context widget being unsubscribed from

subscriber - Subscriber object holding the subscription info

Returns:

Error to indicate success of unsubscription

See Also:

Handlers, Handlers.removeHandler(context.arch.handler.HandlerInfo), userRequest(context.arch.comm.DataObject, String, String, int)

pollWidget

public DataObject pollWidget(java.lang.String widgetHost,
                             int widgetPort,
                             java.lang.String widgetId,
                             Attributes attributes)

This method allows a component to poll a remote widget for its attribute values. A list of attributes is provided to dictate which attribute values are wanted.

Parameters:

widgetHost - Hostname of the context widget being polled

widgetPort - Port number of the context widget being polled

widgetId - Id of the context widget being polled

attribute s - Attributes being requested

Returns:

DataObject containing results of poll

See Also:

userRequest(context.arch.comm.DataObject, String, String, int)

updateAndPollWidget

public DataObject updateAndPollWidget(java.lang.String widgetHost,
                                      int widgetPort,
                                      java.lang.String widgetId,
                                      Attributes attributes)

This method allows a component to force a remote widget to update its data and return it. A list of attributes is provided to dictate which attribute values are wanted.

Parameters:

widgetHost - Hostname of the context widget being polled

widgetPort - Port number of the context widget being polled

widgetId - Id of the context widget being polled

attribute s - Attributes being requested

Returns:

DataObject containing results of poll

See Also:

userRequest(context.arch.comm.DataObject, String, String, int)

putDataInWidget

public DataObject putDataInWidget(java.lang.String widgetHost,
                                  int widgetPort,
                                  java.lang.String widgetId,
                                  java.lang.String callback,
                                  AttributeNameValues attributes)

This method allows a component to put context data in a remote widget. It is really intended for components that don't use the context toolkit, but is being included here for possible future use. The method takes a callback and an AttributeNameValues object. The callback is not necessary (can have a null value), and is only used by the remote widget to determine which of the widget's subscribers need to be updated.

Parameters:

widgetHost - Hostname of the context widget to use

widgetPort - Port number of the context widget to use

widgetId - Id of the context widget to use

callback - Callback of the context widget to associate the data with

attributes - AttributeNameValues to put in the widget

Returns:

DataObject containing results of put data

See Also:

userRequest(context.arch.comm.DataObject, String, String, int)

getVersion

public DataObject getVersion(java.lang.String remoteHost,
                             int remotePort,
                             java.lang.String remoteId)

This method gets the version of the given component (server, widget, interpreter).

Parameters:

remoteHost - Hostname of the component being queried

remotePort - Port number of the component being queried

remoteId - Id of the component being queried

Returns:

DataObje ct containing version

See Also:

userRequest(context.arch.comm.DataObject, String, String, int)

getWidgetCallbacks

public DataObject getWidgetCallbacks(java.lang.String widgetHost,
                                     int widgetPort,
                                     java.lang.String widgetId)

This method gets the callbacks of the given widget

Parameters:

widgetHost - Hostname of the widget being queried

widgetPort - Port number of the widget being queried

widgetId - Id of the widget being queried

Returns:

DataObject contai ning callbacks

See Also:

userRequest(context.arch.comm.DataObject, String, String, int)

getWidgetServices

public DataObject getWidgetServices(java.lang.String widgetHost,
                                    int widgetPort,
                                    java.lang.String widgetId)

This method gets the services of the given widget

Parameters:

widgetHost - Hostname of the widget being queried

widgetPort - Port number of the widget being queried

widgetId - Id of the widget being queried

Returns:

DataObject contai ning services of the widget

See Also:

userRequest(context.arch.comm.DataObject, String, String, int)

getWidgetAttributes

public DataObject getWidgetAttributes(java.lang.String widgetHost,
                                      int widgetPort,
                                      java.lang.String widgetId)

This method gets the attributes of the given widget

Parameters:

widgetHost - Hostname of the widget being queried

widgetPort - Port number of the widget being queried

widgetId - Id of the widget being queried

Returns:

DataObject contai ning callbacks

See Also:

userRequest(context.arch.comm.DataObject, String, String, int)

retrieveDataFrom

public DataObject retrieveDataFrom(java.lang.String remoteHost,
                                   int remotePort,
                                   java.lang.String remoteId,
                                   Retrieval retrieval)

This method allows a component to retrieve data from other components.

Parameters:

remoteHost - Hostname of the component being asked for data

remotePort - Port number of the component being asked for data

remoteId - Id of the component being asked for data

retrieval - Description of data to retrieve with any conditions

Returns:

DataObject containing data requested

See Also:

userRequest(context.arch.comm.DataObject, String, String, int)

retrieveDataFrom

public DataObject retrieveDataFrom(java.lang.String remoteHost,
                                   int remotePort,
                                   java.lang.String remoteId,
                                   java.lang.String myId,
                                   Retrieval retrieval)

This method allows a component to retrieve data from other components.

Parameters:

remoteHost - Hostname of the component being asked for data

remotePort - Port number of the component being asked for data

remoteId - Id of the component being asked for data

myId - Id of the "user" trying to access the data

retrieval - Description of data to retrieve with any conditions

Returns:

DataObject containing data requested

See Also:

userRequest(context.arch.comm.DataObject, String, String, int)

retrieveDataFrom

public DataObject retrieveDataFrom(java.lang.String remoteHost,
                                   int remotePort,
                                   java.lang.String remoteId,
                                   java.lang.String attribute)

This method returns a vector containing AttributeNameValues objects for all the the data of a given attribute. e.g. SQL query would be "SELECT attribute FROM table"

Parameters:

remoteHost - Hostname of the component being asked for data

remotePort - Port number of the component being asked for data

remoteId - Id of the component being asked for data

attribute - Attribute to retrieve

Returns:

DataObject containing data requested

retrieveDataFrom

public DataObject retrieveDataFrom(java.lang.String remoteHost,
                                   int remotePort,
                                   java.lang.String remoteId,
                                   AttributeFunctions attributes)

This method returns a vector containing AttributeNameValues objects for all the the data of the given attributes. e.g. SQL query would be "SELECT attribute1,attribute2,...,attributeN FROM table"

Parameters:

remoteHost - Hostname of the component being asked for data

remotePort - Port number of the component being asked for data

remoteId - Id of the component being asked for data

attributes - Names of the attributes to retrieve data for

Returns:

DataObject containing data requested

retrieveDataFrom

public DataObject retrieveDataFrom(java.lang.String remoteHost,
                                   int remotePort,
                                   java.lang.String remoteId,
                                   AttributeFunctions attributes,
                                   java.lang.String attribute,
                                   int compare,
                                   java.lang.Object value)

This method returns a vector containing AttributeNameValues objects for all the the data of the given attributes and a single condition. e.g. SQL query would be "SELECT attribute1,attribute2,...,attributeN FROM table WHERE attributeX > valueY"

Parameters:

remoteHost - Hostname of the component being asked for data

remotePort - Port number of the component being asked for data

remoteId - Id of the component being asked for data

attributes - Names of the attributes to retrieve data for

attribute - Name of the attribute to do conditional on

compare - Comparison flag

value - Comparison value to use

Returns:

DataObj ect containing data requested

retrieveDataFrom

public DataObject retrieveDataFrom(java.lang.String remoteHost,
                                   int remotePort,
                                   java.lang.String remoteId)

This method returns a vector containing AttributeNameValues objects for all the the data. e.g. SQL query would be "SELECT * FROM table

Parameters:

remoteHost - Hostname of the component being asked for data

remotePort - Port number of the component being asked for data

remoteId - Id of the component being asked for data

Ret urns:

DataObject containing data requested

retrieveDataFrom

public DataObject retrieveDataFrom(java.lang.String remoteHost,
                                   int remotePort,
                                   java.lang.String remoteId,
                                   java.lang.String attribute,
                                   int compare,
                                   java.lang.Object value)

This method returns a vector containing AttributeNameValues objects for all the the data and a single condition. e.g. SQL query would be "SELECT * FROM table WHERE attributeX > valueY

Parameters:

remoteHost - Hostname of the component being asked for data

remotePort - Port number of the component being asked for data

remoteId - Id of the component being asked for data

attribute - Name of the attribute to do conditional on

compare - Comparison flag

value - Comparison value to use

Returns:

DataObject containing data requested

askInterpreter

public DataObject askInterpreter(java.lang.String remoteHost,
                                 int remotePort,
                                 java.lang.String remoteId,
                                 AttributeNameValues data)

This method asks an interpreter to interpret some data. It passes the data to be interpreted and gets back the interpreted data.

Parameters:

remoteHost - Hostname of the component being asked for data

remotePort - Port number of the component being asked for data

remoteId - Id of the component being asked for data

data - AttributeNameValues object containing the data to be interpreted

Returns:

DataObject containing the interpreted data

runComponentMethod

public DataObject runComponentMethod(java.lang.String remoteHost,
                                     int remotePort,
                                     java.lang.String remoteId,
                                     java.lang.String methodName,
                                     AttributeNameValues parameters,
                                     Attributes attributes)

This method asks an component to run some non-standard method. It passes id of the component, attributes, and parameters and gets back the result of the method.

Parameters:

remoteHost - Hostname of the component

remotePort - Port number of the component

remoteId - Id of the component

methodName - Name of the method to run

paramete rs - AttributeNameValues object that is parameters with values

attributes - Attributes object that is parameters with values

Returns:

DataObject containing the interpreted data

executeAsynchronousWidgetService

public DataObject executeAsynchronousWidgetService(AsyncServiceHandler handler,
                                                   java.lang.String serviceHost,
                                                   int servicePort,
                                                   java.lang.String serviceId,
                                                   java.lang.String service,
                                                   java.lang.String function,
                                                   AttributeNameValues input,
                                                   java.lang.String requestTag)

This method requests that a widget execute an asynchronous service

Specified by:

executeAsynchronousWidgetService in interface CommunicationsHandler

Parameters:

handler - Handler to handle the results of the service

serviceHost - Hostname of the widget with the service

servicePort - Port number of the widget with the service

serviceId - Id of the widget with the service

service - Name of the widget service to run

function - Name of the particular service function to run

input - AttributeNameValues object to use to execute the serv ice

requestTag - Unique tag provided by caller to identify result

Returns:

DataObject containing the results of the execution request

executeSynchronousWidgetService

public DataObject executeSynchronousWidgetService(java.lang.String remoteHost,
                                                  int remotePort,
                                                  java.lang.String remoteId,
                                                  java.lang.String service,
                                                  java.lang.String function,
                                                  AttributeNameValues input)

This method requests that a widget execute a synchronous service

Specified by:

executeSynchro nousWidgetService in interface CommunicationsHandler

Parameters:

remoteHost - Hostname of the widget

remotePort - Port number of the widget

remoteId - Id of the widget

service - Name of the widget service to run

function - Name of the particular service function to run

input - AttributeNameValues object to use to execute the service

Returns:

DataObject containing the results of the execution request

pingComponent

public DataObject pingComponent(java.lang.String remoteHost,
                                int remotePort,
                                java.lang.String remoteId)

This method pings a component (widget,server, or interpreter) to make sure that it is functioning ok.

Parameters:

remoteHost - Hostname of the component being asked for data

remotePort - Port number of the component being asked for data

remoteId - Id of the component being asked for data

Ret urns:

DataObject containing the results of the ping

quit

public void quit()

This method should be called when the object is going to exit under normal conditions. It stops the CommunicationsObject from receiving any more requests and exits.

See Also:

CommunicationsObject.quit()

runUserMethod

public DataObject runUserMethod(DataObject data)
                         throws InvalidMethodException,
                                MethodException

This is an empty method that should be overridden by the object that extends this class. It will contain the user-defined RPCs.

Parameters:

data - DataObject containing data for user-defined RPC

Returns:

result of RPC

Throws:

InvalidMethodException - thrown if specifie d RPC couldn't be found

MethodException - thrown if specified RPC had an error

See Also:

runMethod(String, DataObject)

runMethod

public DataObject runMethod(java.lang.String methodType,
                            DataObject data)
                     throws InvalidMethodException,
                            MethodException

This method handles both the system-defined, callbacks and user-defined RPCs. If a user-defined RPC is called, this method calls runUserMethods. If a callback is specified, this method runs userCallback. Currently, the only system-defined methods are queryVersion, and userCallback.

Specified by:

runMethod in interface MessageHandler< /A>

Parameters:

methodType - Name of method to run

data - DataObject containing data for the method call

Throws:

InvalidMethodException - thro wn if specified RPC couldn't be found

MethodException - thrown if specified RPC had an error

See Also:

userCallback(context.arch.comm.DataObject), runUserMethod(context.arch.comm.DataObject), queryVersion(context.arch.comm.DataObject)

userCallback

public DataObject userCallback(DataObject data)

This method is called when a callback message is received. It determines which of its registered handlers should receive the callback message and passes it on accordingly. It creates a reply message to the callback request in the form of a DataObject. It handles all error checking.

Parameters:

data - DataObject containing the callback request

Returns:

DataObject containing the callback reply

See Also:

Handlers.getHandler(String), Handler.handle(String, context.arch.comm.DataObject)

queryVersion

public DataObject queryVersion(DataObject query)

This method returns the version number of this component.

Parameters:

query - DataObject containing the query

Returns:

DataObject containing the results of the query

returnPing

public DataObject returnPing(DataObject ping)

This method returns an error message as an answer to a ping.

Parameters:

ping - DataObject containing the ping request

Returns:

DataObject containing the results of the ping

serviceResult

public DataObject serviceResult(DataObject result)

This method handles the results of an asynchronous service request.

Parameters:

result - DataObject containing the results of the aysnchronous service request

Returns:

DataObject containing a reply to the results message

getVersion

public java.lang.String getVersion()

This method returns the version number of this object.

Returns:

version number

setVersion

public void setVersion(java.lang.String version)

This method sets the version number of this object.

Parameters:

version - of the object

setId

public void setId(java.lang.String id)

This method sets the id of classes that subclass this object, for use in sending messages.

Parameters:

id - ID of the class

getId

public java.lang.String getId()

This method returns the id of the class that subclass this object, for use in sending messages.

Returns:

id of the class

getHostAddress

public java.lang.String getHostAddress()

This method gets the address of the machine this component is running on.

Returns:

the address of the machine this component is running on

main

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

Temporary main method to test the BaseObject class