Programming Java 2 Micro Edition for Symbian OS 2004 (779882), страница 74
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Applications on other mobile phones (eitherMIDlets using the Java Bluetooth APIs or native applications) can then‘‘discover’’ the registered MIDlet. The Java APIs return an array of URIsof discovered devices and then an array of URIs for services registeredon a particular device. If the registered MIDlet is not already running, theBluetooth push implementation will launch it. It will even be possible toenable mobile code: the Bluetooth OBEX APIs can be used to transfera MIDlet from one device to the inbox of a Symbian OS phone, fromwhere the user can install it on their phone. Here is Symbian’s roadmapfor Bluetooth:• basic Bluetooth APIs: now• Bluetooth push: next release (Version 8.0)• Bluetooth OBEX: end 2004 or early 2005.8.6.2.2 Symbian OS Version 8.0Symbian OS Version 8.0 (see Figure 8.12) was released to Symbianlicensees early in 2004.
Multimedia and 3D graphics were added tothe platform, enabling more exciting games and entertainment services.SYMBIAN AND JAVAv8.0UEI,JTWI R1Multimedia (JSR 135)File GCF (JSR 75)3D graphics (JSR 184)413CLDC HI 1.1Figure 8.12 Java technology in Symbian OS Version 8.0.Symbian’s implementation of Mobile Media API (JSR 135) gives developers access to all natively supported media types, which in generalwill also include dynamically installed codecs. The Mobile 3D Graphics API for J2ME (JSR 184) sits on top of the native OpenGL ES API(www.khronos.org/opengles), so that it will benefit from any nativehardware graphics acceleration.The File Generic Connection Framework (GCF) provides access tomedia files (audio, video, etc.), shared areas and private scratch areas.
Itis important for both generic consumer applications and services as wellas enterprise applications.Symbian OS Version 8.0 is compatible with Java Technology forthe Wireless Industry (JSR 185). It also implements the UEI (UniversalEmulator Interface), enabling any Symbian OS phone emulator to bedebugged with any UEI-compliant IDE.8.6.2.3 Symbian OS Version 8.xSymbian will release the next version of Symbian OS in 2004 (seeFigure 8.13). PIM provides access to contacts and calendaring information. This can be used to enhance games, provide additional servicesand deliver mobile support for enterprises.
2D graphics provide vectordrawing facilities appropriate for mapping, engineering drawings andkitchen designs.In the same time frame, Symbian is working on improved Java tools,e.g. for debugging, profiling and heap analysis.Towards the end of 2004 and into 2005 Symbian will add Java APIsneeded to meet the essential needs of the market sectors we identifiedearlier (see Figure 8.14), making it easier to create advanced consumerand enterprise services.
In particular, the example services we’ve lookedat had a number of common themes:• interaction with back-end services• the need for local persistence and data storage• the need to synchronize data with remote services.v8.xEnhancedFigure 8.13PIM (JSR 75)WMA 2.0 (JSR 205)2D vector graphics (JSR 226)Java technology in Symbian OS Version 8.x.414end '04mid '05THE MARKET, THE OPPORTUNITIES AND SYMBIAN’S PLANSWeb services enabling (JSR172)Security and trust (JSR177)Location (JSR179)Content handling framework (JSR211)Data sync (JSR230)Payment API (JSR229)SIP/JAIN (JSR180 etc)Symbian specific:TelephonyPersistence"Send as"Common clipboardFigure 8.14 Forthcoming Symbian Java technology.JSR 172The J2ME Web Services Specification (JSR 172) will be used to interactwith net-based consumer and enterprise services.
In general, clients forweb services tend to be fairly thin, providing little more than a browserinterface. The possibilities are wider on Symbian OS, where different webservices, for instance weather forecasting and traffic flow information,may be aggregated in the same application. JSR 172 relies on SimpleObject Access Protocol (SOAP).
This is a wire protocol similar to theIIOP for CORBA, ORPC for DCOM, or Java Remote Method Protocol(JRMP) for Java Remote Method Invocation (RMI). However, while IIOP,ORPC and JRMP are binary protocols, SOAP is a text-based protocol thatuses XML. It therefore remains to be seen in practice whether SOAP’swordiness will cause bandwidth problems on wireless networks.The RMS provides a very basic persistent store in a flat structure.However, there is no CLDC-compatible JSR for persistent object storageor database access. JDBC Optional Package for CDC/Foundation Profile(JSR 169) provides a JDBC subset for CDC; however, a CLDC-compatibleAPI is yet to be defined.
We should also carefully look for the right model:JDBC supports industry standard SQL, however an object database maybe more natural for the Java language.JSR 230Data Sync API (JSR 230) is currently being defined. It should allowapplications to synchronize data with back-end stores and take part inplatform data sync operations.
It should be independent of the communication protocol, though SyncML is likely to be the most commonimplementation.JSR 177Security and Trust Services (JSR 177) is important for wireless commerce,micropayments, billing, etc. It provides access to a smart card (usually aSIM) using either Application Protocol Data Unit (APDU) commands orRMI access. It also provides a certificate store and cryptography library.SYMBIAN AND JAVA415JSR 179We’ve touched on Location API for J2ME (JSR 179). The Location APIs willallow many location-based services to be developed in Java.
It gives Javadevelopers access to whatever location acquisition methods are providedon the mobile phone, such as A-GPS, GPS, or basic translated Cell ID.The Criteria class is used to select an acquisition method based oncriteria such as accuracy, speed of fix, cost and power. It also provides aLandmarks store that stores coordinate–name pairs: location positions arestored and handled internally as WGS 84 latitude–longitude coordinates,so the ability to convert between a named location and coordinates isessential as users generally work with named locations, for instance,‘‘How far is the Bowling Alley from the supermarket?’’JSR 180Session Initiation Protocol (SIP) is an application-layer control protocolthat can establish, modify and terminate multimedia sessions, as wellas inviting participants to join existing sessions. SIP transparently supports name mapping and redirection services, enabling personal mobilitywhereby users can maintain a single externally visible identifier regardlessof their network location.Five facets of establishing and terminating multimedia communicationsare supported:• user location: determining the end system to be used for communication• user availability: determining the willingness of the called party toengage in communication• user capabilities: determining the media and media parameters tobe used• session setup: establishing session parameters for both called andcalling party• session management: including session transfer and termination, modifying session parameters and invoking services.A useful summary of Java, SIP, and JAIN can be found at www.cs.columbia.edu/sip/Java-SIP-Specifications.pdf.
SIP is probably best known forInstant Messaging and Presence (IM&P) session control. SIP has beenadopted as the baseline signaling protocol for the 3GPP IP MultimediaSubsystem (IMS), which will be available in 3GPP Release 5. SIP couldbe used for mobile phone management, a new application area.There are other use cases, though these assume that the operators havebuilt the corresponding infrastructure:• IP telephony applications and IP-based telephone networks416THE MARKET, THE OPPORTUNITIES AND SYMBIAN’S PLANS• game billingIn a multiplayer game, the game could send a SIP signal to theback-end server saying who lost the game, supporting a ‘‘loser pays’’payment model.
In many cases, only the MIDlet running on the mobilephone knows about the status of the game, so that SIP signaling is theonly way to use this knowledge for charging.• game managementSIP can be used to maintain a game play session until the game isover, even if the mobile phone was turned on and off several timesbetween.
The charge applied can still be a fixed fee for the game,independent of time.• charging and billing for SIP-unaware applications.Games and services may not use SIP interfaces directly, but insteadcould be using open connection, or send message APIs. Underneath, the mobile phone would use SIP signaling appropriate to theapplication and the API, so enabling SIP-based charging and billingintegration even for legacy applications.The SIP for J2ME (JSR 180) specification extends the GCF pattern, whichmeans new SIP connections are obtained through the Connector factory.The specification follows the same simple and lightweight structureas all other MIDP protocol frameworks, e.g. HttpConnection andSocketConnection.
SIP for J2ME is defined at the transaction level inthe same way as HttpConnection. This makes the API specificationmultipurpose, without any assumptions about its intended usage. As aconsequence, a MIDlet that is implemented at the transaction level musthandle message flow. This HTTP-like functionality has been extendedto support receiving Requests that exist in SIP and HTTP, so blockingcalls are extended with an event mechanism that allows applicationdevelopers to choose their optimal programming style.Java APIs for Integrated NetworksJava APIs for Integrated Networks (JAIN) provides wireless devices witha uniform interface to a variety of networks such as wireless, proprietaryInternet, the public switched telephone system, and Asynchronous Transfer Mode (ATM) networks. JAIN is used to reshape proprietary interfacesinto uniform Java interfaces, enhancing application portability.There are four CLDC-compatible APIs for IM&P that use the JAINAPIs.
Whereas the SIP APIs are very low level, these are high-levelservice-oriented APIs:• JAIN Presence (JSR 164) provides a standard, portable and secureinterface to manipulate presence information between a SIMPLEclient (known as a watcher) and a presence server (known as aSYMBIAN AND JAVA417presence agent); SIMPLE extends SIP with support for presence andinstant messaging• JAIN SIMPLE Instant Messaging (JSR 165) provides an interfaceto exchange messages between SIMPLE clients; it is a peer-topeer protocol• JAIN Presence (JSR 186) is a generic API for presence that is independent of the communication protocol (whereas JSR 164 is basedon SIMPLE)• JAIN Instant Messaging (JSR 187) is an API for instant messaging thatis independent of the communication protocol, whereas JSR 165 isbased on SIMPLE, and it uses a presence server for message handling.JSR 186 and 187 require underlying protocol support for specific IM&Pservices.
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