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However,it is not until v9.2 that it is present in both S60 and UIQ devices – in v9.1it is currently only present in devices using UIQ3.Various problems led to us leaving RTP and RTCP out of this book.Firstly, the RTCP API is currently marked as partner-only. Secondly, theSymbian OS RTP implementation currently lacks a few key features. There1The Symbian OS Library contains more information on use of the RComm interface andopening a USB virtual serial port.6INTRODUCTIONis no support for authentication or encryption of RTP packets – in fact,there is currently no support for any profiles, including the Secure Realtime Transport Protocol (SRTP) – this is left to applications to implement.Even if an application wished to try and implement SRTP, low-levelcryptography functionality in Symbian OS is currently exposed viapartner-only APIs.
As a result, it is very difficult to deploy RTP in situations where secure audio support is required and the underlying transportdoesn’t provide its own security. In practice, this would mean that youwould need to use IPSec for RTP over UDP and Bluetooth link layersecurity for any Bluetooth links using RTP, which may not be compatiblewith any system you are trying to integrate with.Hopefully all of these problems will be addressed, and future versionsof this book can include information on RTP. In the meantime, for thoseof you that wish to experiment, documentation can be found in the UIQversion of the Symbian OS Library, under ‘Mm Protocols RTP’.Session initiation protocol (SIP)Symbian OS v9.2 contains a SIP stack.
A similar implementation has beenavailable as part of the S60 UI platform for a number of releases now,and has appeared in some, but not all, S60 devices. However, as withRTP, we have chosen not to write about SIP until the situation regardingavailability in devices and recommended APIs has been resolved. Formore information on SIP in v9.2, consult the S60 3rd edition, FeaturePack 1 documentation.1.3 Expected Level of KnowledgeThis book assumes you have had some experience of developing for Symbian OS, and that you are aware of the basic paradigms – active objects,the client–server framework, and descriptors and have an understandingof the basic types of Symbian OS classes (e.g., C-, R-, T-, M-classes) andhow they behave.If you are new to Symbian OS, or want to take a refresher course inthese concepts, there are several books that you could read, includingSymbian OS C++ for Mobile Phones, and Symbian OS Explained, whichoffers an excellent guide to the basics of programming for Symbian OS.In addition, we assume you’re familiar with the concepts of theplatform security model used in Symbian OS since v9.0.
We describecapabilities required to perform operations in this book, as well as theother impacts that platform security has, but we don’t dedicate space tothe underlying concepts. For more details, you can read the Symbian OSPlatform Security book, although it goes into a lot more depth than isrequired to understand our discussions in this book. There is a sampleSTRUCTURE OF THIS BOOK7chapter from the book available on the Symbian website – this containsa good description of the three key concepts of platform security, andis well worth reading.
There is also a good FAQ about platform securityavailable from the Forum Nokia website, http://www.forum.nokia.com.In terms of required communications knowledge, we assume you’refamiliar with the usage of SMS, MMS, email and HTTP, so have an understanding of the features they provide. More mobile-specific technologies,such as OBEX, Bluetooth, IrDA and Device Management, have morebackground information as we assume that these technologies may notbe as familiar to most developers, especially those from a PC background.We also assume that you are able to set up a general development environment for Symbian OS development – you have installed theappropriate UI platform software development kit (SDK), an integrateddevelopment environment (IDE), if you choose to use one, and are atthe stage where you can build software for both emulator (again, if youchoose to use it – we strongly advise that you do) and the target platform (whichever phone(s) you choose to test on).
However, we don’trequire you to know about setting up the emulator for comms development – we have a chapter towards the end of the book explaining howto do this for various different technologies. Obviously testing on actualhardware is also extremely important, and in some cases the only way totest your application. In this case though we have little to say in termsof setting it up – the hardware features of your phone are fixed, andmost of the configuration issues we discuss in relation to the emulatorsimply don’t apply – the settings have already been configured for yourparticular device.1.4 Structure of this BookThis book is divided into four main sections.
The first section – chapters 1and 2 – aim to give an overview of the book and its contents. It alsoprovides an introduction to the communications functionality in SymbianOS, and a high-level overview of how it all fits together.The second section – chapters 3 through 7 – covers lower level communications technologies.
Roughly speaking, these are technologies thatexist, in Symbian OS, below a socket interface – Bluetooth, TCP/IP,IrDA – or technologies that provide simple data links, such as virtual serialports,2 or other core services such as telephony. Each of these technologiesacts as the underlying layer for the functionality covered in Section III.2Real serial ports, of the RS-232 variety, have died out completely from phones, andthese days only exist on development boards.
As this book is targeted at developers usingphones rather than development boards as their target hardware, we only discuss serialports in the context of the virtual serial ports provided by Bluetooth and IrDA.8INTRODUCTIONThe third section – Chapters 8 through 12 – covers higher level technologies, such as the messaging framework and plug-ins (for SMS, MMSand email), the SendAs service, OBEX, hypertext transfer protocol (HTTP)and OMA Device Management (OMA DM).
As these technologies buildupon those discussed in Section II, some APIs from that section will berevisited here – for example, the HTTP APIs expose the RConnectionAPI. So whilst each chapter tries to stand alone, it might be necessaryto read an earlier chapter to understand all that is being described.
Seesection 1.7 for a more comprehensive reading guide.The fourth section – Chapter 13 – contains practical information ondeveloping with Symbian OS. This includes information on settingup the development environment for various types of comms-relateddevelopment. Much development can be done using the Symbian OSemulator – we discuss various ways of connecting the emulator to an IPnetwork, and using an IR pod, Bluetooth hardware and a phone with theemulator. Finally, there is a brief chapter about future developments, covering new features or areas of technology that are likely to be interestingin the future. If enough of these changes take place, it will be time for usto start writing a new book!The sample code provided in this book is designed to be droppedstraight into your application – this means it doesn’t use the shortcutsseen in other examples, where the code will work in the standaloneexample but needs rework before you can use it in your application.Where there is additional work needed, for example where errors needto be handled in an application-specific way or we have omitted somecode for the sake of clarity, this will be shown clearly – this means youcan spend more time working on the interesting part of your application,and less figuring out why our code doesn’t work in your application!1.5 To which Versions of Symbian OS does the Informationin this Book Apply?This book targets Symbian OS v9.1 and v9.2.
Symbian OS v9.1 is theversion used in S60 3rd edition and UIQ 3.0 phones. In version 9.0of Symbian OS, a new security model was introduced which affectedthe usage of many APIs. This book describes the APIs after the securitychanges were made. Some APIs have changed very little, some have hadmethods replaced, and some have been removed completely.In cases where the API that we are discussing is significantly differentin an older version of Symbian OS, information will be presented in abox like this one.
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