The Hermes Framework User`s Manual
Contents
1. GISlite Properties Fil Debugging gislite debug true Screen Size gislite screen width 240 gislite screen height 300 17 Initial Scale gislite scale 2760 3848 grslit Scal Teach factor 2 5 Initial Center of Map gislite center lat 53 341442 gislite center lon 6 2501383 Data Sources gislite source count 3 gislite source buffer 1024 gislite source 3 type shp gislite source 3 file shapefiles country shp gislite source 2 type shp gislite source 2 file shapefiles building_outlines shp gislite source l type shp gislite source l file shapefilesNNtext shp Projection EQUIRECTANGULAR gislite projection EquiRectangular gislite projection Orthographic gislite projection Lambert gislite projection Mercator Parametric Line amp Polygon Clipping Algorithms gislite projection clip line CohenSutherland gislite projection clip line LiangBarsky gislite projection clip poly SutherlandHodgman gislite projection clip poly WeilerAtherton gislite projection clip poly Maillot gislite projection clip points threshold 150 gislite projection clip area multiple 3 Generalisation gislite geometry filter lod MinimumAreaFilter gislite geometry filter lod tolerance 20 Geometry Simplification gislite geom uetzy crease ell Cassatt2. Listing 16 Creation of ContextCapsules for the Riddles From RiddleManager s constructor 25 As another example of a context capsule the following code from RiddleHunt creates an end of game capsule that notifies the application that the game should end The capsule is available to be activated when the current time is equal to or later than the time in the capsule The activated content is an application specific BehaviorContent RHBehaviorContent with behavior type RHBehaviorContent END GAME TYPE that is described below Now add the EndGame capsule _gameDurationInMinutes Hermes getProperties getPropertyAsInt hermes riddlehunt gamedurationinminutes _timeGameOver _gameDurationInMinutes 60 1000 System currentTimeMillis BehaviorContent endGameContent new BehaviorContent new Object RHBehaviorContent END GAME TYPE ContextCapsule endGameCapsule new ContextCapsule new Content endGameContent new Context Communication getLocalAddress 1 endGameCapsule setTimeUntilReactivation _timeGameOver addContextCapsule endGameCapsule Listing 17 Creation of the end of game ContextCapsule 3 7 2 Add those ContextCapsules to the ContextCapsuleManager Add those ContextCapsules to the ContextCapsuleManager s context capsule collection with the addcontextCapsule ContextCapsule capsule E g the end of game ContextCa
3. 5 2 List of Figures FIGURE 1 DISTRIBUTION CONTENTS FIGURE 2 HOW GISLITE WORKS WITH HERMES FIGURE 3 HERMES FRAMEWORK COMPONENT ARCHITECTURE FIGURE 4 WHERE AM I INTERFACE FIGURE 5 RIDDLE HUNT FIGURE 6 HERMES PLATFORM FIGURE 7 COMPILATION DEPENDENCIES 35
4. index spati geom a index spati el index spati el a index spati a index spati ise to R Tree Spatial Indexing gt 40 max node entries 9 storage pagesize 512 rtree maxnodecapacity 12 rtree minnodecapacity 5 erance 3 try generalise threshold 6000 rtree nodesplit Quadratic FKindex spatial rtree nodesplit Linear cache size 8 Listing 5 Sample GISlite Properties File 18 3 2 2 Data Sources The data sources referred to in the above properties file must match the path to a shp ESRI Shapefile Examples of such files can be found in gislite shapefiles A dbf attribute record file is required for each shapefile but all other files in this directory will be generated if missing by GISlite The following table lists the file extensions that may be found in this directory and the purpose of the files Note As GISlite will generate files while running and place them in this folder it must be writeable Extension Description SHP Shapefile containing geometry Multiple shapefiles may appear with similar names in this directory These are multi resolution caches of the original SHP file and can be safely removed at any time DBF dBase Attribute database SHX Shape Index Flat index providing faster access to large SHP files SSX Spatial Index Flat index providing minimum bounding rectangle based access to SHP file
5. 23 Extending Map Layer in your application 28 For more information on MapLayers please consult the API documentation that accompanies GlIsSlite 3 10 Initialising your application The following steps should be done to create a Hermes application All of the sample code comes from RiddleHunt class 3 10 1 Call init methods of Hermes and GlSlite The application code initializes Hermes and GISlite through their static init calls If you ve extended any of the factories mentioned above Cont extFactory CommunicationMessageFactory orContextQueryFactory new instantiations of these classes should be passed into the init method of Hermes This constructor for RiddleHunt begins by calling both init methods with the appropriate parameters GIS lite Amie In Hermes properties file too _selfName GISlite getProperties getProperty PERSON NAME KEY Need to pass in all the hooks for the init selfName new RHContextFactory new RHCommunicationMessageFactory new RHContextQueryFactory Hermes application User the Hermes Logger for debugging messages Gales sleet 3 10 log Hermes 10g Listing 24 Calling init methods of 2 Privacy settings Hermes and GISlite After calling the init methods the privacy settings for each type should be set using Privacy s addContextToDisclose allows disclosure of context based on type The application should call this met
6. Basis Profile Foundation Profile Connected Device Configuration CDC J2ME IBM Websphere Everyplace Micro Environment WEME Pocket PC ARM XScale based processor Figure 6 Hermes Platform 2 3 IDE All the code in this package was developed using WebSphere Studio Device Developer Device Developer is an integrated development environment for the creation and testing of applications that will be deployed on handsets and other small devices 2 4 Compiling To compile all the source included in this distribution it is necessary to be aware of the compilation dependencies for each of the projects 2 4 1 External Package dependencies For each of the projects there are a number of external libraries which are required to compile and run the code The table below lists these dependencies In all instances the dependant libraries are included in the distribution and can be found in the lib directory of the appropriate project Uo Project Jar Detail GISlite n a n a Hermes db4o 6 1 javal 1 jar Object database engine kxml min jar Very small memory footprint XmlPull Parser optimized for J2ME RXTXcomm jar Provides access to serial ports in Java Table 1 External Package dependencies 2 4 2 Internal Package Dependencies The projects themselves are dependant on each other In order to compile Hermes you will need to have GISlite on the build path In order to compile any of the examples you will ne
7. CommunicationMessageFactory for the application 3 7 Using Application Specific Context Capsules Much like a time capsule gives a clearer picture of the time period at which it was created a context capsule stores content along with Surrounding Context Information SCI that allows the application to interpret that content in its original context This content can be anything an application can interpret such as a behavior or a piece of context Context capsules allow an application to activate its content when its SCI is sufficiently similar to the device s current context e g if the context capsule s element location in its SCI is similar to the device s current location For more information on 24 context capsules please refer to the paper Preserving Context with Context Capsules listed in the Related Documents section of this document In the Hermes framework the Cont extManager periodically compares the device s current context to the SCI of each ContextCapsule If the contexts are similar the ContextCapsule s Content is activated The Content can bea piece of context such as an Activity ora Trail ContextContent class or a behavior such as turning on a light or presenting a collection of riddles BehaviorContent class To use context capsules in a new application four tasks need to be carried out Create any ContextCapsules necessary for the application 2 Addthose ContextCapsules to the ContextCapsu
8. features Attributes are held in a dBASE format file Each attribute record has a one to one relationship with the associated shape record 1 2 Hermes Framework 1 2 1 Introduction Hermes is a software framework for mobile context aware trails based applications which will support developers by providing generic components containing structure and behaviour common to all trails based applications At the most general level a trail can be thought of as a collection of activities with associated locations and a dynamically reconfigurable recommended visiting order The trail is a collection of connected locations rather than a strict sequence since it may contain alternative sub routes to cater for such variables as different modes of transport or user preferences Trails underpin a wide range of useful applications for a mobile user who has a set of activities that may or should be carried out throughout the day at different locations Combining the trails concept with mobile context aware technology creates opportunities for innovative activity based application development Mobile context aware applications are those that run on wireless devices e g PDAs and smartphones and have an awareness of the physical and social situation in which they are deployed Examples of trails applications that are both mobile and context aware include tour guides courier support management systems basic route planners treasure hunt games and student sup
9. in Mobile Context Aware Trails Based Applications 3rd Uk UbiNet Workshop Designing Evaluating and using Ubiquitous Computing Systems University of Bath February 2005 e Cormac Driver Eamonn Linehan Siobh n Clarke Andrew Jackson Shiu Lun Tsang Mike Spence A Framework for Mobile Context Aware Trails based Applications Experiences with an Application led Approach Submitted to the What makes for good application led research in ubiquitous computing Workshop at Pervasive 2005 Munich Germany e Siobhan Clarke Cormac Driver Context Aware Trails IEEE Computer Vol 37 No 8 pp 97 99 August 2004 Invisible Computing column 33 Cormac Driver Siobh n Clarke Hermes Generic Designs for Mobile Context Aware Trails based Applications Workshop on Context Awareness at MobiSys 2004 Boston Cormac Driver Siobh n Clarke Hermes A Software Framework for Mobile Context Aware Trails Workshop on Computer Support for Human Tasks and Activities at Pervasive 2004 Vienna 34 5 Appendix 5 1 Code Listing LISTING 1 SAMPLE HERMES PROPERTIES FILE CONTENTS LISTING 2 HERMES INITIALIS ATION LISTING 3 LOGGING LISTING 4 DEFAULT LOGGING PROPERTIES FILE LISTING 5 SAMPLE GISLITE PROPERTIES FILE LISTING 6 THE SIGNATURE OF THE CONTEXTFACTORY METHOD FOR CREATING CONTEXT LISTING 7 AN EXAMPLE OF A SETTER THAT CALLS UPDATETIMESTAMP LISTING 8 AN EXAMPLE OF THE CLONE METHOD FOR THE TRAIL CONTEXT
10. 19 beginning of those methods and setting it back to true after all the setters have been called This should be done for any methods that want to set the attributes of the Context but do not wish to update the timestamp e g the clone merge and fromXML methods all with to populate a Context object s attributes but do not wish to update the timestamp For an example see the clone and merge discussion below o Aclone method must be implemented if a deep copy of any structure is required The clone method from the Trail Context is shown below A deep copy of the Trail s Activity array and Activity HashMap is required Notice the _shouldSetTimestamp statements described above surrounding the setter public Object clone Trail clonedTrail Trail super clone clonedTrail _shouldSetTimestamp false A deep copy of the Activity array and the Activity map Activity clonedActivities null if activities null clonedActivities Activity activities clone lonedTrail setActivities clonedActivities Q clonedTrail _shouldSetTimestamp true return clonedTrail Listing 8 An example of the clone method for the Trail context o toXML and fromXML for converting Context to and from XML for use in CommunicationMessages As mentioned above f romXML needs turn off any timestamp update if it uses a setter o merge also needs to dictate what behavior to execute when
11. 4 3 7 1 Creating Context Capsules sesiis eiee E R E EE een eene entente tren 25 3 7 2 Add those ContextCapsules to the ContextCapsuleManager esee 26 3 7 3 Create any application specific Content classes seseeeeeeeeeeeereene 26 3 7 4 Start the ContextCapsuleThread essere enne nennen nenne 27 3 8 Using Application specific Context Queries eese esee ee eres seen eee enses enata seta seta sno 27 3 9 Creating an interface for your application eese eese eese ee seen eren seen ette sten sns ennt en as tnae 28 3 10 Initialising your application esee eere eese eese eene ee nete seen setas tn tasto setas ease ease ease ease easet 29 3 10 1 Call init methods of Hermes and GISlite essere 29 3 10 2 Privacy settIngs ie ete etr ecd tet e p er dee e amer et 29 3 10 3 Setting wp the Interface eoe eR SRI On ond Here 29 3 10 4 Registering for updates in Context en eene nenne 30 3 10 5 Linking other ContextChangedEventListeners to the ContextManager 30 3 10 6 Adding ContextSoUtCes siete beatur ei e PIRE PITE Reden 31 3 10 7 Registering to receive ApplicationMessages essere 31 3 10 8 Creating new instance of the ContextCapsuleManager if necessary 31 3 10 9 Starting the ContextCapsuleThread if necessary sse 32 4 RELATED DOCUMEN
12. Factory data structures via the addNewContextType call The first argument is the Context type s String the second is a prototype for creating new Context objects and the last designates this context type as abstract or not In RiddleHunt the RHContextFactory has these calls in its constructor to add the Game and Player types Add any types that are not added by the super classes addNewContext Type RHContextType GAME new Game false addNewContext Type RHContextType PLAYER new Player false Listing 11 Calls made in RHContextFactory constructor to add new types of Context o Finally if any of the new types require a special Cont extQuery to retrieve context this needs to be created by extending the ContextQueryFactory as described in Section 3 8 3 4 Creating new Context Sources The framework is designed so that new context types and context sources can be easily added It is a simple process to implement the code to support a new type of context source Context sources can be anything from a new type of sensor to an online service Hermes contains a GPS context source ready to use and this code serves as an example of how to create your own context sources public class GPSReceiver extends ContextSource The ContextTypes that GPS receivers can deliver private static final String _gpsContextTypes 21 ContextType LOCATION private static final ContextServiceDescription _con
13. LISTING 9 AN EXAMPLE MERGE METHOD FOR SUBCLASSES OF CONTEXT LISTING 10 CONTEXT TYPE STRING ATTRIBUTES OF RHCONTEXTTYPE LISTING 11 CALLS MADE IN RHCONTEXTFACTORY CONSTRUCTOR TO ADD NEW TYPES OF CONTEXT LISTING 12 CREATING A CONTEXTSOURCE LISTING 13 ADDING A CONTEXT SOURCE TO THE APPLICATION LISTING 14 DIRECTING THE INPUT XML TO THE CORRECT RHAPPLICATIONCOMMUNICATIONMESS AGE CLASS LISTING 15 SUBCLASS OF COMMUNICATIONMESSAGEFACTORY LISTING 16 CREATION OF CONTEXTCAPSULES FOR THE RIDDLES FROM RIDDLEMANAGER S CONSTRUCTOR LISTING 17 CREATION OF THE END OF GAME CONTEXTCAPSULE LISTING 18 ADDITION OF END OF GAME CONTEXTCAPSULE LISTING 19 THE BEHAVIOR TYPES FOR RHCONTENTBEHAVIOR LISTING 20 RIDDLEHUNT S METHOD TO HANDLE CONTEXTCAPUSLE BEHAVIORCONTENT LISTING 21 RUNNING THE CONTEXTCAPSULETHREAD LISTING 22 CREATING AN APPLICATION SPECIFIC CONTEXT QUERY LISTING 23 EXTENDING MAP LAYER IN YOUR APPLICATION LISTING 24 CALLING INIT METHODS OF HERMES AND GISLITE LISTING 25 SET ALL THE PRIVACY SETTINGS LISTING 26 CONFIGURING THE CONTEXTLAYER LISTING 27 REGISTERING FOR THE TYPES OF CONTEXT NEEDED BY THE APPLICATION LISTING 28 LINKING THE CONTEXTLAYER CONTAINING THE ACTIVITIES TO THE CONTEXTMANAGER LISTING 29 ADDING A GPS CONTEXTSOURCE LISTING 30 REGISTER TO RECEIVE APPLICATIONMESSAGES LISTING 31 CREATE A NEW INSTANCE OF THE CONTEXTCAPSULEMANAGER LISTING 32 RUN THE CONTEXTCAPSULETHREAD
14. NS WITH HERMES 15 3 1 Configuring Hermes R 15 SA Properties file csere ee e Ree IG YER PO FU EH EEG EE NR HIM ont 15 3 1 2 AMI AL SUB e505 fa eee eren on ede e te 16 34 3 EOgEH BI sen Reden enn odi eae e on ien ees 16 32 Configuring NIIT R 17 3 2 1 Properties Hle see oe v ee ne ee Pri ede 17 3 22 Data SOUPCES ise ere aee QE ERO verd Ur dv trt bere ee ee Heredes 19 3 3 Adding New Types of Context 4 eere eee eres eene esee e eene ense te setas tassa seas etas e ease ense tasto 19 3 4 Creating new Context Sources eere eee e eee eee ee enses enata ense ta tune tasse enses enses suse tasas ua 21 3 5 Connecting Context Sources eee ee eee ee eeee eese tn atten seen usva sse ta senten sesto sees suse tatu nena 22 3 6 Defining new types of Messages eeeeeeee eese e eene n etnies tastes tn seen tn seta tuse ta sensns estos sesso seta suus 22 3 6 1 Application specific CommunicationMessages esseeeeeeeee eee 23 3 6 2 Superclass for the application specific CommunicationMessages s s s 23 3 6 3 Subclass the CommunicationMessageFactory seseeeeeeeeeeeeneee nennen eene 23 3 6 4 Pass the subclass of the CommunicationMessageFactory into Hermes init 24 3 7 Using Application Specific Context Capsules e eere eese eese tenete eene ene tn setas etant 2
15. TS iixisasu ci c day ku duh ed LEE rh d3a aa na GRE eR nnmnnn 33 5 APPENDIX e 35 5 1 GET R H 35 5 2 List OF Figures M M soni 35 1 Package Contents This section describes the contents of this package and the directory structures within the Hermes framework distribution c RiddleHunt Figure 1 Distribution Contents 1 The GISlite project is a standalone library for accessing manipulating and displaying spatial data This library is used by the example applications to provide an interface to display contextual information This project contains the following sub directories e bin The compiled java code e dist A packaged Jar or jxe file containing all the compiled code and resources from the bin directory e src the source code e doc Javadoc API documentation 2 The Hermes project contains the framework itself The directory structure within the project is the same as for the GISlite project e Nbin The compiled java code e dist A packaged jar jxe file containing all the compiled code and resources from the bin directory e src the source code e doc Javadoc API documentation 3 The Examples directory contains three example applications e Where Am I Demonstrates the Hermes framework being used to gather location context from a GPS context source and the GISlite project being used to display this i
16. W DS Distributed Systems Group 9 Trinity College Dublin The Hermes Framework User s Manual amonn Linehan Mike Spence hermes dsg cs tcd ie intel The Hermes Framework User s Manual Version 1 0 July 2007 Copyright O Distributed Systems Group Department of Computer Science Trinity College Dublin 2007 AII rights reserved Comments may be addressed to Dr Siobh n Clarke Distributed Systems Group Department of Computer Science Trinity College Dublin 2 Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation with no Invariant Sections no Front Cover Texts and no Back Cover Texts A copy of the license available for download from http hermes dsg cs tcd ie All code listings in this document are part of the Hermes Framework for the development of Mobile Context aware Trails based Applications The Hermes Framework is free software you can redistribute it and or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation version 3 of the License The Hermes Framework is distributed in the hope that it will be useful but WITHOUT ANY WARRANTY without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE See the GNU General Public License for more details A copy of the GNU Lesser General Pu
17. ation is interested in receiving any ContextChangedEvents it should implement the Context ChangedEventListener interface The application should then register its interest in any context types by calling the Hermes setiInterestl nContextTypes method For RiddleHunt the application is interested in receiving new Player and Game contexts Subscribe to changes in Game Context and Instruct Acquisition to acquire Game Context Hermes setInterestInContextTypes this RHContextType PLAYER 100 Hermes setInterestInContextTypes this RHContextType GAME 100 Listing 27 Registe ring for the types of Context needed by the application 3 10 5 Linking other ContextChangedEventListeners to the ContextManager The application should also that are interested in receivi link any other ContextChangedEventListeners ng Context updates In RiddleHunt the RiddleHuntMapLayer is interested in receiving Trail updates So the contextLayer will show activies on the map Hermes rex Interest ial ate esee oes re oua ibrenyensr RECON eese yore ERAT qeu Listing 28 Linking the C ontextLayer containing the Activities to the ContextManager 30 3 10 6 Adding ContextSources Any local ContextSources such as GPS devices should be initialized In RiddleHunt the Location is generated from an attached GPS device This ContextSource is added through a call to ServiceDiscovery s updateContextSourceList m
18. blic License is distributed with the Hermes Framework It can be found in a file named COPYING txt If not see lt http www gnu org licenses gt Contents 1 PACKAGE CONTENTS rasic uci o ic cuan ina gan anda aE n Cu Ek a da R RI Sura Eo FREE Ur RA 6 1 1 OIM 7 1 1 1 Introduction esee trit orn e EHE PR PER EPA ER ERE to e ue Ene 7 1 1 2 Features pirno nen E nere ER REIP T re E p P porre ee IS p ie Pee 8 1 2 rn SERENAS 9 LXI TIntFfOdUC IOTE uo ere rte o A tls teme AU e oeste A I Ee RR GE OR 9 IP APEEP Unicum EHE 9 1 3 Example Applications R M 11 ES Where Am 1 2 unserer epe Ert peteret ipee eter erra 11 132 Where Are We 255 sea phe eh it ER teaser ien Neue beers e pestes 11 I3 3 RiddleHu nt eng sias eee neige eph hae a tele epe 12 2 DEVELOPMENT ENVIRONMENT ceeeeeeeeeeeene nennen 12 2 1 Hardwa te s ccssssrssssrserssssrsesesssrsessessneeseceneessseneesssseseesessessesesceseneeseesensesceesnessesessessesessessesess 12 2 2 PlatfOrM s scercereessrceresssrsersessrsessessrsesssseseesessesenseeseseesessesensesseseessseseeessseesessesessesseseesesseses 12 2 3 IDE EE RA A T E A 13 2 4 COMPING pe oes eS E 13 2 4 1 External Package dependencies rene eene nnne 13 2 4 2 Internal Package Dependencies eeeseeseeseseeeseeeeeennen nennen enne nnne nnn enne 14 3 BUILDING APPLICATIO
19. comms serial provider J2MESerialConnection The Context Container to use hermes context container provider DB40ContextContainer hermes context container provider InMemoryContextContainer PF CONLE Dewe SLEE hermes context container objectcontainer file data db4o Hhermes context container objectcontainer file Storage Card Hermes data db4o t GPS PC hermes comms gps comm 4 hermes comms gps baud 9600 GPS IPAQ hermes comms gps comm 7 hermes comms gps baud 9600 Context Capsule properties hermes context capsules capsulesleeptime 5000 15 Trail Generation hermes trail subtrail size 5 hermes trail reconfiguration interval 10000 the trail reconfiguration strategy hermes trail reconfiguration strategy brute hermes trail reconfiguration strategy genetic Hhermes trail reconfiguration strategy annealing hermes trail reconfiguration relevence threshold 0 8 Debugging hermes debug log sysout true hermes debug log file data hermes log hermes debug log file Storage Card Hermes data hermes log Listing 1 Sample Hermes Properties File Contents 3 1 2 Initialising The Hermes framework includes a static class that is used to initialise all the framework components integrate these components where necessary and provide a single point of access to the framework for your application To initialise the framework in your application the follo
20. ed both GISlite and Hermes on the build path GISlite __ E Figure 7 Compilation dependencies 14 3 Building applications with Hermes This section covers all the tasks necessary to build a context aware trails based application using a combination of GISlite and the Hermes framework 3 1 Configuring Hermes Many of the frameworks components are configurable in order to support different hardware platforms This section covers everything needed to configure the framework for use by an application 3 1 1 Properties file A properties file is used to store all the configuration settings for the framework components The framework requires this properties file to run and looks for it in the current working directory config hermes properties The properties file itself 1s a list of key value pairs Each pair is on a separate line and lines beginning with are comments Hermes Properties File DO NOT EDIT Communication properties hermes comms threads incoming 2 hermes comms samemachine false hermes comms heartbeattimeout 30000 hermes comms broadcast port 4446 hermes comms broadcast sleepinterval 10000 hermes comms listening timeout 10000 hermes comms listening sleep 5000 hermes comms receive timeout 5000 hermes comms receive sleep 5000 hermes comms incoming sleep 2000 E E A W A W A A A ANA The Serial Comms API to use J2ME PC Linux hermes comms serial provider J5SerialConnection hermes
21. etContextServiceDescriptions Discover the context Source Hermes getCommunication getServiceDiscovery updateContextSourceLi st Gps Listing 13 Adding a Context Source to the application 3 6 Defining new types of Messages If new types of ComnunicationMessage are needed four steps need to be carried out 1 Create the application specific CommunicationMessage 2 Create a superclass for the application specific CommunicationMessage 3 Create a subclass of the CommunicationMessageFactory 4 Pass the subclass of the CommunicationMessageFactory into Hermes init 22 3 6 1 Application specific CommunicationMessages A subclass of CommunicationMessage needs to be created for every new concrete type of message an application requires These need to override the messageHelper method that converts its data to XML and contain a createXXXMessage method that creates a new message from XML where XXX stands for the specific type of message In RiddleHunt the only new message is the StartGameApplicationMessage that extends RHApplicationMessage see below This class overrides messageHelper and contains the method createStartGameApplicationMessage 3 6 2 Superclass for the application specific CommunicationMessages e Ifthe new CommunicationMessage is a subclass of ServiceMessage ContextMessage orApplicationMessage that superclass itself must be extended These new subclasses direct t
22. ethod SerialAddress serialPort new SerialAddress short commPort baudRate GPSReceiver gps new GPSReceiver serialPort gpsTypes ContextServiceDescription gps getContextServiceDescriptions Discover the context Source Hermes getCommunication getServiceDiscovery updateContextSourceList gps Listing 29 Adding a GPS ContextSource 3 10 7 Registering to receive ApplicationMessages The application must also implement the App1icationMessageEventListener interface and register with Communication if it wants to receive any application messages In RiddleHunt the application extends this interface and registers through the following call We want to listen for application messages Hermes getCommunication addApplicationMessageEventListener this Listing 30 Register to receive ApplicationMessages 3 10 8 Creating new instance of the ContextCapsuleManager if necessary Initialize and start ContextCapsule thread if necessary In RiddleHunt the ContextCapsuleManager is the RiddleManager The RiddleManager is created in the application constructor and the ContextCapsuleHandler is passed as an argument in this case RiddleHunt implements the ContextCapsuleHandler interface Starting Riddle Manager _riddleManager new RiddleManager activities this Listing 31 Create a new instance of the ContextCapsuleManager 3l 3 10 9 Starting the ContextCapsuleThread i
23. f necessary The ContextCapsuleThread is started once the game has begun Starts thread that loops through all ContextCapsules riddleManager launchContextCapsuleThread Listing 32 Run the ContextCapsuleThread 32 4 Related Documents e Cormac Driver An Application Framework for Mobile Context Aware Trails PhD thesis Trinity College Dublin 2007 e Siobhan Clarke Mike Spence Cormac Driver and amonn Linehan Using Collaborative Context for Dynamic Mobile Trails Generation Intel Research Council Year 3 Renewal Document May 2006 e Mike Spence Siobhan Clarke Preserving Context with Context Capsules The Third International Workshop on Modeling and Retrieval of Context AAAI 2006 Boston MA e Cormac Driver Eamonn Linehan and Siobh n Clarke Analysis of the Evaluation of Application Led Research in Pervasive Computing Technical Report TCD CS 2006 26 4 May 2006 e Mike Spence Cormac Driver Siobhan Clarke Sharing Context History in Mobile Context Aware Trails Based Applications Ist International Workshop on Exploiting Context Histories in Smart Environments ECHISE 2005 Pervasive 2005 Munich Germany e Eamonn Linehan Cormac Driver Siobh n Clarke Route Generation for Adaptable Trails Based Applications 3rd Uk UbiNet Workshop Designing Evaluating and using Ubiquitous Computing Systems University of Bath February 2005 e Mike Spence Cormac Driver Siobhan Clarke Collaborative Context
24. he messages of the newly created types to their corresponding classes with their corresponding createXXXMessage methods In RiddleHunt the ApplicationMessage is extended by RHApplicationMessage which directs any StartGameApplicationMessages to the correct method public static RHApplicationMessage createApplicationMessage XMLElement element RHApplicationMessage retMessage null String messageTypeString element getAttributeValue messageType if messageTypeString null int messageType try messageType new Integer messageTypeString intValue catch NumberFormatException nfe messageType UNKNOWN MESSAGE TYPE if messageType START GAME TYPE retMessage StartGameApplicationMessage createStartGameApplicationMessage element else Hermes log error createApplicationMessage Unknown Message Type t messageType RHApplicationMessage class return retMessage La 2 Xm Listing 14 Directing the input XML to the correct RHApplicationCommunicationMessage class 3 6 3 Subclass the CommunicationMessageFactory The application must provide a method for the framework to create an application specific method if it receives one To do this the 23 CommunicationMessageFactory must be extended and the createSpecificMessage method must be overridden This method handles the creation of any of the application specific messages by calli
25. hod for every type of Context that it wishes to share with other users Any type not explicitly disclosed will not be shared by the application RiddleHunt shares the Game Player and Location contexts with other devices in the game method This currently only Configure what Context types we are willing to show and how often getPrivacy addContextTypeToDisclose ContextType LOCATION Hermes OOO Hermes LOO Ones Hermes LOOO gt 2 3 10 getPrivacy addContextTypeToDiscl getPrivacy addContextTypeToDisc lose RIC Onbe te To C PLAYER lose RHContextType GAME Listing 25 Set all the privacy settings 3 Setting up the Interface 29 An interface created using the GISlite Library API is then added to the application The code snippet below also shows a map centring control being used to keep the map centred on the data in the RiddleHunt layer Add ContextLayer to Map RiddleHuntMapLayer contextLayer new RiddleHuntMapLayer GISlite getMapContext getProjection Hook up Map Centering Code iy leIlmpl GRID LAYER STYLE centerMap new MapCentering GISlite getMapContext contextLayer Have map centering listen for moving points contextLayer addLayerListener centerMap GISlite getMapContext addLayer contextLayer List ing 26 Configuring the ContextLayer 3 10 4 Registering for updates in Context If the applic
26. ing game in which the application assists users in playing the game by both presenting context information such as other players locations and by generating trails designed to help the player win the game The version of the game included in this package is not the full version but is provided as a illustration of how to expand the capabilities of the framework components to handle extensions such as previously undefined types of context and new sensors 2 Development Environment This section provides the information necessary to build the source in this package 2 1 Hardware All the software in this package was designed to run on a PDA like device supporting a Java VM The software has been successfully tested during development on HP IPAQ h6300 devices running Windows Mobile 2003 and IBM Workplace Client Technology Micro Edition JVM 2 2 Platform The Hermes framework is written in Java but is designed for the JO Java VM The J9 VM is an implementation of the Java Virtual Machine Specification Version 1 3 J9 VM can be downloaded as part of IBM Workplace Client Technology Micro Edition 5 7 from the IBM website requires registration Included in this download is J9 a k a IBM WebSphere Everyplace Micro Environment The following diagram illustrates the platform on which Hermes is designed to run 12 Trails Based Applications GlSlite amp Hermes JXE Native Compilation amp Optimisation Personal Profile Personal
27. lasses should export debugging information which level of debugging is required info debug or error and also whether to dump the logging information to the default output stream or write it to a file An example of the default settings for this file is the following RHLog Properties file DO NOT EDIT Example To hog rom every class ie tcd cs dsg hermes true To Log from every class except riddle hunt ie tcd cs dsg hermes true ie tcd cs dsg hermes app RiddleHunt true To log from only RiddleHunt class ie tcd cs dsg hermes fals ie tcd cs dsg hermes app RiddleHunt true NOTE Omitting a class name is equivalent to setting it to false PER CLASS LOGGING SETTINGS FOLLOW ie tcd cs dsg hermes true ie tcd cs dsg hermes comms MessageInputStream false END Listing 4 Default Logging Properties File 3 2 Configuring GISlite This section covers the configuration of the GISlite library so that it may be used alongside Hermes to produce an interface to a trails based application 3 2 1 Properties file GISlite requires its own properties file which must be placed in the path gislite gislite properties from the current working directory This file specifies the configuration options of the algorithms that are included in this library as well as specifying the data sources from which to retrieve spatial data These data sources must be ESRI Shapefiles
28. leManager s ContextCapsule collection Create any application specific Content classes 4 Start the ContextCapsuleThread 3 7 1 Creating Context Capsules The RiddleHunt code below creates ContextCapsules that let the application know that riddles associated with a Location are available to be attempted when the player s location intersects the capsule s location The activated content is an application specific BehaviorContent RHBehaviorContent with behavior type RHBehaviorContent RIDDLE_LOCATION_ACTIVATED_TYPE that is described later in this section I Set up geometry that if a Location is within the Geometry the capsule can be activated Location bBox Location Hermes deeConbextrPactory creareNnewContexe RHContext lype LOCAT EON bBox setLocationGeometry new BoundingBox location getLocationAsPoint RIDDLE SQUARE SIDE LENGTH RIDDLE SQUARE SIDE LENGTH Create the Content which is a RiddleLocationActivated BehaviorContent bContent new BehaviorContent new Object location RHBehaviorContent RIDDLE LOCATION ACTIVATED TYPE Create and add the capsule to the CapsuleStaging and location to context Capsule map ContextCapsule capsule new ContextCapsule new Content bContent new Context bBox Communication getLocalAddress TIME UNTIL REACTIVATION _locationToContextCapsules put location capsule adaContextCapsule capsule
29. merging two Contexts of the same type E g a common merging strategy is to populate the Context with the values of whatever Context has the most recent timestamp As mentioned above merge should turn off any timestamp update if it uses a setter public boolean merge Context c boolean changed false if c instanceof Player ite leues Ue hen ers ep _shouldSetTimestamp false If the above was merged that means there should be some new data if super merge player this setScore player getScore this setStrategy player getStrategy this setIsGamesMaster player isGamesMaster j changed true 20 ShouldSetTimestamp true return changed Listing 9 An example merge method for subclasses of Context Adding new types of Context requires an extension of a few classes beyond the actual Context classes o ContextType should be extended to store the static Strings representing the new context types In RiddleHunt the class extending ContextType is RHContextType and contains the Strings public static final String GAME Game public static final String PLAYER Player Listing 10 Context type String attributes of RHContextType o Inaddition ContextFactory should be extended to add the new Context types to the list of Context currently available and allows the new types to be created via the ContextFactory This is done by adding the new types to the Context
30. nformation on a map e Where Are We Extends the WhereAml application to add a demonstration of the Hermes frameworks ability to share context between devices In this case the map display shows where neighbouring users are on the screen e RiddleHunt A treasure hunt game involving the solving of riddles built using the Hermes framework Note RiddleHunt code included here is incomplete It is provided as an example of using the framework and is not a playable version of the game The following sections will introduce and describe the major features of each of the packaged libraries 1 1 GlSlite Library GISlite is a helper library for Hermes that facilitates the generation of a map based spatial context visualisation at different resolutions and levels of detail for mobile users 1 1 1 Introduction The GISlite library is designed to facilitate the rendering and reasoning over vector map data on mobile devices The library is designed to be very simple to use and features an intuitive API The API makes it easy to add additional layers to the map and to manipulate the map For example map layers can be added to illustrate contextual information or custom controllers can be written to orientate and scale the map based on the user s location GISlite also supports spatial reasoning and route generation The following diagram illustrates the level at which the GISlite library is integrated into the component view of the Hermes frame
31. ng the correct createXXXMessage method This will be a static method of a specific concrete ComnunicationMessage or an extension of an existing abstract superclass e g in RiddleHunt RHApplicationMessage extends the abstract ApplicationMessage Ifthe type of message passed in is not a newly created type the input is passed on to the createSpecificMessage method of the superclass In RiddleHunt RHCommunicationMessageFactory extends CommunicationMessageFactory which contains the overridden createSpecificMessage method In this case the only application specific CommunicationMessage is an RHApplicationMessage The other CommunicationMessages are passed on to the superclass CommunicationMessageFactory public CommunicationMessag createSpecificMessage int messageClass XMLElement element retMessage null CommunicationMessag if messageClass Communicat retMessage RHApplicationMessag else ionMessage APPLICATION MESSAG E CLASS retMessage super createSpecificMessage return retMessage messageClass Listing 15 Subclass of CommunicationMessageF actory 3 6 4 Pass the subclass of the CommunicationMessageFactory into Hermes init createApplicationMessage element Finally a new instance of the subclass of CommunicationMessageFactory must then be passed as a parameter to the init method of Hermes in order to assign it as the
32. onsible for proactively seeking out and acquiring specific types of context on behalf of an application The trust component works with acquisition to augment incoming messages with trust related metadata On the outbound side of the collaboration components are the sharing and privacy components The sharing component is responsible for responding to incoming requests for context and the privacy component provides for the protection of personal data by limiting which types of context are exchanged with which peers Above the collaboration layer is the context management layer containing the context container and modelling component The modelling component handles the fusion of context and the conversion of incoming context to the context manager s internal representation In addition to the modelling component there is a context container that is responsible for storing context persistently The context container can hold context in memory or persist it to disk in response to the freshness of the context and the memory available on the device The context container makes its context available by providing an interface for context queries and also making it possible for applications to register to be notified if a particular context changes It is at this level that many other context aware toolkits end their support for application developers In contrast Hermes contributes two additional closely collaborating components that provide solutions for a n
33. port systems The following section will give an overview of the architecture of the framework 1 2 2 Architecture Applications j e Trails e Context Management Modeling Context Container A ee Collaboration inbound outbound Communication Discover Figure 3 Hermes framework component architecture Figure 3 Hermes framework component architecture shows a component level view of the of the Hermes framework The diagram describes a layered software framework in which each layer is self contained and is isolated from the effects of changes in other layers through a combination of interfaces event based call backs and message passing The architecture diagram should be read from a bottom up perspective as each ascending layer in the architecture builds upon the functionality of lower layers At the bottom layer of the architecture is the communication component It is the responsibility of this layer to manage the communication with sensors infrastructure and peer devices over a variety of networks This layer also manages bandwidth and the discovery of other devices supporting the Hermes framework Above communication are the components that support collaboration in the Hermes framework They are seperated into columns to illustrate the separation between the inbound and outbound aspects of collaboration On the inbound side left are the acquisition and trust components The acquisition component is resp
34. psule created above is added with the following line addContextCapsule endGameCapsule Listing 18 Addition of end of game ContextCapsule 3 7 3 Create any application specific Content classes If an application uses ContextCapsules new application specific Content will probably need to be created RiddleHunt uses anew BehaviorContent called RHBehavior that defines the types for the context capsules described in the previous sections Riddles are available to be presented public static final int RIDDLE_LOCATION_ACTIVATED_TYPE 1 The game is over public static final int END GAME TYPE 2 Listing 19 The behavior types for RHContentBehavior Once the content of a ContextCapsule has been activated the Content is sent to the ContextCapsuleHandler The RiddleHunt class is a 26 ContextCapsuleHandler and handles the previously described Content as follows public void handleBehaviorContent BehaviorContent behavior Context sci DeviceAddress creatorsDevice if behavior getBehaviorType RHBehaviorContent RIDDLE LOCATION ACTIVATED TYPE The first param is a Location Location of the Riddle Object obj behavior getParam 0 if obj null amp amp obj instanceof Location Location riddleLocation Location obj _riddleManager presentRiddles riddleLocation else Hermes log error First Behavior parame
35. records QIX A Quad tree spatial index Table 2 Data source file extensions 3 8 Adding New Types of Context To demonstrate adding new types of Context to an application we will use examples from RiddleHunt s application specific Contexts Game and Player Game extends the abstract Context Artefact and Player extends the concrete Context Person Several methods need to be overridden o A protected constructor without arguments The constructor is protected because all Context should be created with the following ContextFactory method public Context createNewContext String type Listing 6 The signature of the ContextFactory method for creating Context o Alloutside access to a Context object should be done through setter methods This is particularly important as the Context objects must keep track of when they were last updated in order to aid in recognizing stale Context among other considerations This timestamp maintenance is carried out by the inclusion of an updateTimestamp call in all the setters An example from Player follows public void setScore int i updateTimestamp _score i Listing 7 An example of a setter that calls updateTimestamp As a consequence of having the updateTimestamp call in the setters it must be disabled when using the setters and the timestamp should not be updated This is done by setting the Context attribute _shouldSetTimestamp to false at the
36. ter should be a Spatial Feature this else Hermes log debug Unknown behavior type this Listing 20 RiddleHunt s method to handle ContextCapusle BehaviorContent 3 7 4 Start the ContextCapsuleThread Start the ContextCapsuleThread with ContextCapsuleManager s launchContextCapsuleThread Now launch the thread super launchContextCapsuleThread Listing 21 Running the ContextCapsuleThread 3 8 Using Application specific Context Queries The ContextQueryFactory allows new context queries to be created If a new context type requires a Cont extQuery different than the standard ContextTypeQuery in the Hermes framework a new ContextQuery should be created The ContextQueryFactory should also be extended In RiddleHunt RHContextQueryFactory does this by overriding the ContextQueryFactory screateContextTypeQuery method to call the newly created PlayerQuery s constructor when encountering a Player type public ContextQuery createContextTypeQuery String contextType String name ContextQuery returnQuery null if contextType equals RHContextType PLAYER returnQuery new PlayerQuery name else returnQuery super createContextTypeQuery contextType name 21 return returnQuery Listing 22 Creating an application specific context query 3 9 Creating an interface for your application The GISlite library provides a simple map based interface that can be easily e
37. textServiceDescriptions ContextServiceDescription getDescriptionsFromType _gpsContextTypes true public GPSReceiver SerialAddress serialPortAddress Setting the last time this was updated to be MIN_VALUE so it will always get updated super new Device GPS Receiver serialPortAddress _contextServiceDescriptions System currentTimeMillis 5000 Listing 12 Creating a ContextSource The important aspects of this code listing is that every context source must have a reference to an underlying instance of Device a set of service descriptions and a period to control the polling of the device The service descriptions define the types of context available from this device in this case just location and their format This information is used by the framework to determine how to format and model the information as context 3 5 Connecting Context Sources Once the decision of which context sources should be available to the application is made and the code extending the generic Cont ext Source class for each one is written it is necessary to inform the framework that at runtime it should connect to the context source and acquire its context This is facilitated by a single call to the static Hermes class SerialAddress serialPort new SerialAddress short commPort baudRate GPSReceiver gps new GPSReceiver serialPort ContextServiceDescription sd ContextServiceDescription gps g
38. umber of technical challenges common to trails based applications Theses components are the trails component and GIS component The trails component is responsible for the generation and management of trails The GIS component is responsible for maintaining a model of the structure and geography of the user s environment for the purpose of supporting more intelligent reasoning by the trails component and improving the overall user experience of trails based applications 10 1 3 Example Applications A number of example applications are included in the package We list them here in order of complexity 1 3 1 Where Am I This is the first example application It is very small only two classes and is intended to demonstrate the integration of GISlite and Hermes libraries by the addition of a map layer that overlays contextual information gathered by the Hermes framework over a GISlite map rendering IBl x gem A INE Haeo Pui PLACE 5 LINCOLN A FE MERRION CLOSE Ward By ES Hotel T dinis MERRItC NE Scale 1 2 760 Figure 4 Where Am I Interface 1 3 2 Where Are We The second example builds on the first example In this application in addition of producing a map layer showing a single piece of contextual information a map layer showing the locations of all other people discovered by the Hermes framework on the map interface 11 1 3 3 RiddleHunt Figure 5 Riddle Hunt Riddle Hunt is a multiplayer riddle solv
39. wing statement should be executed Hermes init appKey Listing 2 Hermes Initialisation The _appKey parameter uniquely identifies the application initializing the framework This is used to distinguish among multiple applications accessing the framework in the case while debugging that multiple framework instances reside within the same JVM For a specific application this string can be assigned to anything 3 1 3 Logging The Hermes framework includes a configurable logging utility that an application can call to print or record debugging information To log information a statement similar to the following should be added Hermes log info Hermes Framework c DSG 2007 Hermes class Listing 3 Logging There are also Hermes log debug and Hermes log error methods The methods take two parameters The text to log and the class if static or object that the message is coming from An example of how the Hermes logger may format this example would be INFO 01 08 2007 2 45 15 Hermes Hermes Framework c DSG 2007 main 16 The reason the class name is required is that the logging can be filtered by class This is important because the volume of debugging information may be significant For example it may be desirable to see all the debugging messages from just a single class To allow for such configuration there is a properties file included as a resource in the build of Hermes that specifies which c
40. work kd RENDER b Jm PROJ CTION H H E E EGE HW EHE EE EE RGEGRGEEEEEEEEREENEEREENEEBEEEEEERNRERNRENERNENN S Se ul E e rte errem sen urn omm zoom ow Collaboration inbound outbound guo ne Acquisition Sharing Communications Figure 2 How GISlite works with Hermes 1 1 2 Features e Equirectangular and Cylindrical cartographic coordinate system projections e Vector data rendering and retrieval from ESRI Shapefiles e Multi resolution spatial visualisation featuring scale sensitive level of detail and line simplification e Online continuous generalisation via nth algorithm for simple features coast lakes rivers etc and a variation of the Douglas Peuker algorithm for complex features e Track up orientated spatial visualisation e Rectangular polygon and line clipping to reduce the number of points to be drawn and further speed up rendering Wriler Atherton Sutherland Hodgeman and Liang Barsky algorithms implemented Shortest path topographical route generation Quad tree region based spatial indexing Support s zoom pan and rotate operations Support for spatial operations such as containment intersection union and distance on all features ESRI Shapefiles store nontopological geometry and attribute information for spatial features The geometry for a feature is stored as a shape comprising a set of vector coordinates Shapefiles support point line and area
41. xtended to produce an interface for your application This is achieved by adding layers to the map display This is supported by the MapLayer An example of a very simple MapLayer follows Once created your custom map layers can be added to the map interface by calling GISlite getMapContext addLayer public class ContextMapLayer extends DynamicMapLayer implements ContextChangedEventListener Cache of the users location so that UI can be rendered without querying context model every time private Point dotLocation public ContextMapLayer RotatableProjection projection Style style super Context Layer projection style Try to get curent location ContextQuery q Hermes createContextTypeQuery ContextType LOCATION Hermes MY NAME Context c Hermes getContext q if c null amp amp c length gt 0 dotLocation Location c 0 getLocationAsPoint public void render Graphics g if dotLocation null dotLocation render g this _projection StyleImpl1 HIGHLIGHT_STYLBE public void handleContextChangedEvent ContextChangedEvent event if event getContext getContextType equals ContextType LOCATION Update myLocation Point Location loc Location event getContext this dotLocation loc getLocationAsPoint Trigger Redraw layer and center if necessary this fireLayerChangedEvent Listing
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