maemo 4 Quick Start Guide
Contents
1. coding and decoding and interfacing with the device s hardware Using this approach developer does not have to bother with details like low level hardware management audio and video compression schemes etc If the elements included with the OS are not enough more can be either compiled for maemo or new ones can be developed Developer documentation for GStreamer can be found at the project s website 23 6 2 Stream encoding and decoding Maemo devices include a wide arsenal of video and audio codecs which enables the maemo applications to read and write nearly all commonly used video and audio for mats These are supported also by the GStreamer framework For many purposes the developer doesn t even have to specify the used codecs implicitly since GStreamer au tomatically detects the format and which codec to use The playbin 22 GStreamer base plugin provides a convenient abstraction layer for all audio and video content 16 maemo maemo 4 Quick Start Guide Copyright 2007 Nokia Corporation Malmo 6 3 Audio Due to non technical reasons most of the codecs are not distributed with the SDK which is good to keep in mind when developing applications relying on such features 6 3 Audio For audio programming maemo has two main APIs GStreamer and ESound Usually system sounds such as sounds for notifying user for an event e g battery low is played through ESound More sophisticated operations for example playing music files o2. maemo maemo 4 Quick Start Guide 27 Copyright 2007 Nokia Corporation TM macmo 11 maemo org Chapter 11 maemo org The landing site and home for maemo open source community developers is maemo org It provides documentation community support bug reporting and com plete project hosting for the developers This chapter goes though these services 11 1 Documentation The maemo org site provides official documentation 43 for each maemo major release in the form of tutorials how tos and API documentation Also this Quick Start Guide is part of the official documentation The community documentation is viewable for everyone and editable by registered users in the maemo wiki 55 Contributions to the community wiki and feedback about the official document are welcome 11 2 Support The place to get support from the community is the mailing list for maemo developers 51 Prior to asking a possibly frequently asked question on the list it is good to take a look at the mailing list archives 44 A separate list for maemo users is also very active targeted more to the end users than maemo application developers The most active maemo instant messaging channel at the time of writing is the maemo IRC channel 49 on freenode Commercial support for the maemo platform will be provided by Forum Nokia 12 11 3 Bug Reporting The proper way of giving feedback about the maemo platform is by using the public maemo Bugzilla 40 It ca
3. user and HildonWizardDialog for creating wizard user interfaces For information 12 maemo maemo 4 Quick Start Guide Copyright 2007 Nokia Corporation Malmo 4 2 Graphical user interface elements with GTK about Hildon s widgets good resources are Maemo Tutorial 36 and Maemo API References 24 Another important element of the Hildon framework is the Hildon Input Method API which is an interface for creating new user input systems in addition to the in cluded virtual keyboard and handwriting recognition Extending Hildon Input Methods How to 11 describes the API s usage in detail 4 20 Graphical user interface elements with GTK User interfaces of maemo applications are created using GTK 26 user interface toolkit GTK is widely used in UNIX GUI applications perhaps most notably the GNOME desktop environment is based on it The Hildon desktop builds on top of a modified GTK 2 10 called maemo GTK 2 10 47 in a very similar manner all Hildon widgets are also GTK widgets GTK itself is based on and uses several lower level libraries with all having a specific role When developing applications using GTK usually the developer will also explicitly use some of these libraries e GObject 21 provides object orientation by GType system and signal handling e GLib 15 has tools for general non graphical programming tasks such as dif ferent data structures memory allocation file operations multithreading and interfacin
4. gobject maemo maemo 4 Quick Start Guide Copyright 2007 Nokia Corporation BIBLIOGRAPHY Malmo 22 Gstreamer playbin base plugin http gstreamer freedesktop org data doc gstreamer head gst plugins base plugins html gst plugins base plugins playbin html Gstreamer project s home page http gstreamer freedesktop org Gtk api documentation http www gtk org api Gtk project s home page http www gtk org Gtk web site http www gtk org Hildon http live gnome org Hildon Hildon application manager documentation http hildon app mgr garage maemo org doc html Hildonmm project page https garage maemo org projects maemomm How to use camera api http maemo org development documentation how tos 4 x how to use camera api html htop an interactive process viewer for linux http htop sourceforge net Implementing custom connection managers http maemo org development documentation how tos 4 x implementing custom connection managers html Jalimo http www jalimo org Kernel guide for maemo http maemo org development documentation how tos 4 x kernel guide for maemo html maemo 4 0 porting guide http maemo org development documentation how tos 4 x maemo 4 0 porting guide html Maemo 4 0 tutorial http maemo org development documentation tutorials maemo 4 0 tutorial html Maemo api reference http maemo org development documentation apis maem
5. of the modules like WLAN come as binary only which means that the module APIs should remain unchanged if kernel is changed by a developer 3 20 Base distribution Maemo is based to a large extent on the same open source components found in the Debian 7 Linux distribution Maemo builds on GNU Linux for operating system core and GNOME GTK for user interface architecture Maemo uses the same component packaging system as Debian dpkg tool s binary packages New packages can be installed old ones can be removed and the whole sys tem can be upgraded by the package management framework The file system structure also comes from Debian In order to run the software on a Internet Tablet various optimizations and enhance ments have been made These include power management related issues touchscreen input performance and size optimizations In order to reduce space maemo uses a shell and command line tools from Busybox 4 Also notably the maemo platform adheres closely to the GNOME Mobile Platform 16 At the time of writing maemo uses all the same components as this platform except for service discovery maemo maemo 4 Quick Start Guide 9 Copyright 2007 Nokia Corporation malmo 3 3 Application framework The maemo architecture guide 39 goes gives more detailed information of the overall maemo architecture 3 3 Application framework The purpose of an application framework is to help application development by pro v
6. option can also be used As other general guidelines CPU over usage must naturally be avoided This goes also for completely redundant operations such as unnecessary screen updates Also when an application is not visible it should be inactive to prevent it from slowing down the application user is currently interacting with 10 2 Resource Usage Resource usage has to be taken into account with maemo applications very carefully because if an application takes up too much resources it cannot be used The resources that are scarce are RAM flash network bandwidth file descriptors and IO bandwidth Also besides base memory usage also memory leaks must be naturally avoided There are tools such as Valgrind 76 to help detecting possible memory leaks 10 3 Power consumption The device is not usable if user needs to recharge it all the time or if it runs out of battery while idle Therefore no polling or busy looping should be used anywhere 26 maemo maemo 4 Quick Start Guide Copyright C 2007 Nokia Corporation Malmo 10 4 Secure Software Design Instead an event based approach like GTK s main loop is a better alternative Also too freguent timers or timeouts are to be avoided 10 4 Secure Software Design Quality and robustness together produce secure software A document 67 describ ing secure software design on maemo platform will give details about creating secure software and the specific issues on mobile platforms
7. KANG m 2 Terms and Definitions 3 Architecture Dal Ga AA Rare a a k e BS Goh ee Sa A Ea 2 4 Base CISMIDMMOM exo Ye ss Ys e BLDG GG 2 3 Application framework cs os uoo owe RE RE ES 3 4 maemo compared to desktop Linux distributions 4 User Interface Development Al Hidondesktop 2 2 24 55 240446054 2806 deeb de 2 4 2 Graphical user interface elements with GTK 5 Important System Services 51 Filesysten GnomevES ecu k k RR Ew Re ee eS NG 5 2 Application Preferences GConf 32 DBUS k Ro REX Oe Re eee awa S ee SA Othersystem Services ceba boron SOY Y DA BG XM Mos GG 6 Multimedia 6 1 GStreamer multimedia framework 6 2 Stream encoding and decoding Go AUDIO LL OG VCO uou ex ACE ES ete a Xd 9 DE UR XE ete NG 65 Digital Signal Processor cx Ry orc S Sa 6 6 Graphics and MARES lt isos RR TERES D ME LT 7 Communications 7 1 Acquiring internet ACCESS aaa a om o n 7 2 VoIP Instant Messaging and Presence 7 3 Address Book and Contacts 02000200 TAP Bluetooth uo lS k k a a e URS Ee s maemo maemo 4 Quick Start Guide Copyright 2007 Nokia Corporation OON tA Un a m O oos j 12 12 13 14 14 14 15 15 16 16 16 17 17 17 17 18 19 19 19 19 malmo CONTENTS 8 Development Environment 21 8 1 maemo software developmentKkKit 21 8 2 Packaging de
8. Making application packages http maemo org development documentation how tos 4 x making application packages html 57 Matchbox home page http matchbox project org 58 Mono http www mono project com Maemo 59 Multimedia architecture http maemo org development documentation how tos 4 x multimedia_architecture html 60 Openobex home page http dev zuckschwerdt org openobex 61 Oprofile a system profiler for linux http oprofile sourceforge net 62 Pango reference manual http library gnome org devel pango 63 Pymaemo home page http pymaemo garage maemo org 64 Quality awareness http maemo org development documentation how tos 4 x quality_awareness html 65 Ruby maemo bindings project page https garage maemo org projects ruby185 66 Scratchbox home page http scratchbox org 67 Secure software design TODOnotpublishedwithmaemoChinookBETA 68 strace http sourceforge net projects strace 69 Telepathy http telepathy freedesktop org maemo maemo 4 Quick Start Guide Copyright 2007 Nokia Corporation BIBLIOGRAPHY Malmo 70 71 72 73 Ubuntu for debian developers https wiki ubuntu com UbuntuForDebianDevelopers Ubuntu home page http www ubuntu com uclibc http www uclibc org Using alarm interface http maemo org development documentation how tos 4 x using alarm interface html Using gam
9. TM macmo maemo 4 Quick Start Guide October 29 2007 maemo maemo 4 Quick Start Guide Copyright 2007 Nokia Corporation malmo Copyright 2007 Nokia Corporation All rights reserved Nokia Forum Nokia and maemo are trademarks or registered trademarks of Nokia Corporation Other product and company names mentioned herein may be trademarks or trade names of their respective owners Disclaimer The information in this document is provided as is with no warranties whatsoever including any warranty of merchantability fitness for any particular purpose or any warranty otherwise arising out of any proposal specification or sample This docu ment is provided for informational purposes only Nokia Corporation disclaims all liability including liability for infringement of any proprietary rights relating to implementation of information presented in this docu ment Nokia Corporation does not warrant or represent that such use will not infringe such rights Nokia Corporation retains the right to make changes to this document at any time without notice License This work is licensed under a Creative Commons Attribution Share Alike 3 0 License 2 maemo maemo 4 Quick Start Guide Copyright 2007 Nokia Corporation TM macmo CONTENTS Contents 1 Introduction 1 1 Hisioryand Philosophy o com Re RR RR GB RAANG nG 12 DatgetaudieD6e o ous spo mene eh Red ex 1 3 Reading instructions 0 oom e eo
10. acks and from his herself not from other users Maemo also uses suid root binaries and etc password where as Ubuntu enforces the use of sudo and shadow passwords Unlike Ubuntu maemo makes use of a root account like Debian does but has a triv ial default password The user should really change the root password before installing e g OpenSSH to the device with root login 3 4 3 Base system differences The greatest difference in the base system is that maemo uses a lightweight BusyBox 4 replacement for the essential GNU utilities 20 on the device e g s and sh In maemo kernel and initfs reside in separate partitions and cannot be updated with a package manager like with a common desktop Linux Programs in initfs use uClibc 72 instead of glibc Ubuntu has Perl and Python languages as essential packages Debian has only Perl and maemo has neither Maemo has no debconf Ubuntu uses Upstart for device startup instead of SYSV init scripts used in maemo maemo maemo 4 Quick Start Guide 11 Copyright 2007 Nokia Corporation TM macmo 4 User Interface Development Chapter 4 User Interface Development The maemo platform s basic starting point for graphical user interface programming is the Hildon 27 an application framework comprising of a lightweight desktop a set of widgets optimized for handheld devices a set of theming tools and other complemen tary libraries and applications Hildon is based on GNOME 17 technologies
11. andatory for a package to exist in any repository but it has significant advantages user can easily update packages other developers can use the packages as automatically installable dependencies and the repository s packages can be found using Application Manager Information for working with repositories can be found in the Debian Repository HOWTO 8 8 2 3 One click install Maemo also has a option to create installation instruction files that enables the users to install applications simply by clicking a link on a web site The install files contain required repository and package names The format of these files is really simple and it s described in Hildon Application Manager documentation 28 8 3 Programming languages Currently C is the only official programming language for maemo But thanks to the community unofficial support exist for several other languages To name a few the SDK itself compiles C and by adding hildonmm bindings 29 Hildon applications can be created the C way Python scripting language also has a good support in form of pymaemo 63 and Ruby bindings are in the works 65 not to forget Mono 58 For Java support JaliMo 33 is an interesting project to track 24 maemo maemo 4 Quick Start Guide Copyright 2007 Nokia Corporation TM macmo 9 Porting Software Chapter 9 Porting Software Much effort has been done in the design of maemo platform to allow easy porting of regular GNU Linux de
12. cratchbox by internally using the host computer s tools without emulation when possible For example compilation on ARMEL environment is actually done by an x86 ARMEL cross compiler but Scratchbox hides the details so that the developer can execute GCC like on any GNU Linux system 8 1 2 Development on maemo SDK The maemo SDK provides all of its development tools inside Scratchbox Also the Hildon Desktop is started with a single command af sb init start inside Scratchbox However the Hildon Desktop needs a secondary X server of proper size and bitdepth to be displayed on As an exception to the rule the X server such as Xephyr 78 must be started on the host Linux environment instead inside Scratchbox The use of Xephyr is described in the maemo SDK tutorial 36 8 1 3 Development tools on Scratchbox As the Scratchbox environment is practically a full GNU Linux system it includes the standard GNU Linux development tools Debugging is done with tools like GDB 13 valgrind 76 Itrace and strace 68 Performance profiling can be done with tools like htop 31 oprofile 61 and time and compiling with the GCC toolchain Some of these tools offer graphical user interfaces which can also be used Of course this isn t a comprehensive list of the tools and if the tools shipped with the SDK don t suit to needs or personal preferences most utilities can be easily run practically unchanged in Scratchbox The Maemo Tutorial 36 is a good introduct
13. d root file systems One set is provided for both X56 and ARMEL architectures on top of a working Scratchbox installation More Scratchbox information can be found at Scratchbox s web site 66 8 2 Packaging deploying and distributing For installing and managing application packages maemo uses the popular Debian package management system From the user s perspective this is quite invisible as the package management is done using the Application Manager Under the hood it presents a flexible package framework which enables developers to easily create instal lable and manageable packages without having to concentrate on the actual implemen tation details of the management 8 2 1 Deb installation packages The Debian package management system uses deb packages which in addition to files that will installed consist of meta data describing the package dependencies to other packages and optional installation and removal scripts The process of creating the packages is fortunately made quite simple by various package development tools The process of creating packages is described in the Making Application Packages document 56 maemo maemo 4 Quick Start Guide 23 Copyright 2007 Nokia Corporation malmo 8 3 Programming languages 8 2 2 Package repositories The package management system makes use of package repositories which are essen tially web or FTP sites that contain packages and some information about them It isn t m
14. e software It is simple to get started even if concepts like cross compilation or touchscreen user interface design are not familiar to the reader Those familiar with GNU Linux GTK toolkit and C programming language will feel right at home This guide is also a good starting point for software development for any platform or device related to the GNOME Mobile family As well as giving an introduction on new frameworks libraries and tools provided by maemo overall design concepts for this new generation of internet capable devices are explained 1 1 History and Philosophy The maemo platform was introduced when the first Nokia Internet Tablet was an nounced at the LinuxWorld Summit in New York City on May 25th 2005 The design philosophy of maemo is to be a real desktop computer in the mobile hardware The tar get is that the system is easily extendable being easy to create new and bring existing desktop applications to the platform Maemo uses known open desktop frameworks to enable easy software portability and familiarity This strategy is quite different compared to many Linux based media players and phones that are closed or require special development tools About 9096 of the maemo platform is open and the majority of that comes from upstream open source projects The rest that is closed consists of e g parts of the user interface and device drivers owned either by Nokia or third party providers One important philosophy is to enab
15. elopment Environment Chapter 8 Development Environment The development environment for maemo running on the desktop is called maemo SDK 54 It will only install and run on a Linux operating system Supported Linux distributions for maemo SDK are currently Debian and Ubuntu but installing maemo SDK is also possible for other distributions On other operating systems such as Win dows a VMWare image 80 can be used to provide a working Linux environment 8 1 maemo software development kit The maemo SDK creates a sandboxed maemo development environment on a GNU Linux desktop system largely built on a tool called Scratchbox 66 In most ways this environment behaves like the operating system on the device but with added development tools This means that the development process is very similar to normal desktop GNU Linux and the kinks of embedded development such as cross compiling are handled transparently by Scratchbox 8 1 1 Hardware architectures Maemo SDK comes with two environments for two architectures x86 is used for native performance and better tool support though native execution without need for emulation ARMEL is used for working with the actual device s architecture Both have their advantages and roles in maemo development It is important to understand that maemo SDK actually provides these two environments as preconfigured targets inside a working Scratchbox installation This is explained in detail later Generally
16. er en hancements Corresponds to Nokia Internet Tablet SE 2006 version 2 2006 39 14 Gregale maemo 2 2 release bugfixes and enhancements Bora maemo 3 x releases corresponds to Internet Tablet OS releases 1 2006 47 20 2 2006 51 6 maemo 3 0 3 2007 10 7 maemo 3 1 and 4 2007 26 8 4 2007 38 2 maemo 3 2 Chinook maemo 4 0 release Diablo future maemo release Elephanta future maemo release maemo maemo 4 Quick Start Guide Copyright 2007 Nokia Corporation TM macmo 3 Architecture Chapter 3 Architecture This chapter describes the high level architecture of the maemo platform from an ap plication developer s point of view After that a comparison of maemo and popular Ubuntu and Debian desktop Linux distributions is given 3 1 Kernel Maemo uses a Linux 2 6 operating system kernel Linux is an open source operating system developed by thousands of volunteers and companies that share their work un der GNU GPL license Architecturally Linux has a monolithic kernel All kernel code is run under supervisor mode Kernel can be extended at runtime by dynamically load able kernel modules Various APIs exist for device driver file system and networking protocol modules Developers can add new kernel modules The maemo kernel is based on the ARM kernel branch and can be modified re compiled and flashed by a developer The Kernel Guide for maemo 34 gives details of these procedures Some
17. es start up screen http maemo org development documentation how tos 4 x using games start up screen html Using maemo address book apis http maemo org development documentation how tos 4 x using_maemo_address_book_apis html Valgrind http valgrind org Writing hildon desktop plug ins for maemo http maemo org development documentation how tos 4 x writing_hildon _desktop_plug ins_for_maemo html Xephyr http www freedesktop org wiki Software Xephyr Xlib manual http www the labs com X11 XLib Manual Xubuntu image with maemo sdk installed https garage maemo org frs group id 277 maemo maemo 4 Quick Start Guide 33 Copyright 2007 Nokia Corporation
18. g with the underlying operating system e XLib 79 is a library for interacting with an X server GdkPixPuf 14 is used for simple client side image manipulation e GDK 17 is a library between Xlib and GTK that is basically used for drawing widgets handling window events and drag n drop support Pango 62 is used for text rendering and layouting with solid internationalization support e ATK Accessibility Toolkit is used for providing GTK widgets accessibility support More information about GTK and related libraries can be found from the project s web site 26 including GTK API Documentation 37 maemo maemo 4 Quick Start Guide 13 Copyright 2007 Nokia Corporation TM macmo 5 Important System Services Chapter 5 Important System Services The underlying system services in the maemo platform differ slightly from those of used in desktop Linux distributions This chapter gives an overview of the most impor tant system services 5 1 File system GnomeVFS Maemo includes a powerful file system framework GnomeVFS This framework en ables applications to use a vast number of different file access protocols without having to know anything about the underlying details Some examples of the supported proto cols are local file system HTTP FTP and OBEX over Bluetooth In practice this means that all GnomeVFS file access methods are transparently available for both developer and end user just by using the framewor
19. iding a standard structure for an application Applications that have a graphical user interface tend to have a similar structure e g the event driven runtime model The events are triggered by the user for example by touching a button on the touchscreen Events can also be triggered by the application engine itself An example is when new data is received from the network The application framework of maemo is called Hildon It is partially based on the same technologies that GNOME framework is built on most notably the GTK components Hildon has several additions and enhancements to GNOME GTK including Hildon widget set Sapwood theme engine and image server task navigator Hildon control panel and status bar Some of the changes to standard GNOME like Sapwood for instance are to reduce memory requirements and to improve speed on a small hand held device In addition Hildon framework has many features to support mobil ity like automatic state saving touchscreen input methods and window management on a physically small device The programming APIs are familiar to GNOME and GTK developers The frame work has GLib and GObject object management system underneath The GTK widget set is provided with Hildon extensions The interprocess communication is done using D BUS messages The user files are accessed through GNOME VFS and multimedia applications can use GStreamer to get accelerated support for various codecs User configurations are s
20. in active development the x86 environment is used because it provides practically the same performance as normal GNU Linux applications Also although the underlying architecture is different from the actual device programs usually behave exactly as they would when compiled and run on ARMEL As stated before many tools are available only for the x86 environment When an application is running fine in the x86 environment the next step is to compile it for the ARMEL architecture The process for compilation and packaging is exactly the same as in x86 albeit a bit slower because some of the required software is emulated The developer needs not to concern with cross compilation This is the main rationale for maemo SDK to use Scratchbox in the first place maemo maemo 4 Quick Start Guide 21 Copyright 2007 Nokia Corporation malmo 8 1 maemo software development kit The applications compiled in ARMEL environment can be run straight on the de vice Additionally it is possible to run some of the applications inside the ARMEL en vironment in maemo SDK This is possible because of the automatic emulation maemo SDK provides The emulation is not complete and things like multithreading will cause problems so actual testing must be done on the device Using emulation for the whole development process may not sound ideal because of the effect on performance That s why even when in ARMEL environment native performance is achieved with S
21. ion to development using Scratchbox and debugging tools are described in depth in The Maemo Debugging Guide 42 8 1 4 Testing and debugging on device Even though Scratchbox is quite accurate in emulating a full target environment on the device it isn t 10096 identical Especially applications that make use of the device s special hardware can behave differently on the device than on Scratchbox They even may not work at all Fortunately testing the software on device is quite straightforward using either SSH or a tool called sbrsh to run target binaries on the device transparently from Scratchbox The CPU Transparency how to 6 has instructions for getting started with sbrsh SSH server and client for maemo can be downloaded from maemo web site 48 8 1 5 Scratchbox under the hood Scratchbox is maemo SDK s cross compiling environment The default Scratchbox installation works as is under most conditions but some details are good to know for 22 maemo maemo 4 Quick Start Guide Copyright 2007 Nokia Corporation Malmo 8 2 Packaging deploying and distributing more specialized usage The target inside Scratchbox contains a root file system that is being worked on When a new target inside Scratchbox is created a toolchain must be specified for it Using this toolchain applications are built for the target Examples of a target are X86 and ARMEL which are provided by the maemo SDK on top of Scratchbox Host tools are native to
22. k for file opera tions The API for file handling is also much more flexible than the standard platform offerings It features for example asynchronous reading and writing MIME type sup port and file monitoring All user file access should be done with GnomeVFS in maemo applications be cause file accesses can be remote In fact many applications that come with the op erating system on the internet tablets do make use of Gnome VFS Access to files not visible to the user should be done directly for performance reasons A good hands on starting point is taking a look of the GnomeVFS example in maemo examples package Detailed API information can be found from the GnomeVES API reference 18 5 2 Application Preferences GConf GConf is used by the GNOME desktop environment for storing shared configuration settings for the desktop and applications The daemon process GConfd follows the changes in the database When a change occurs in the database the daemon applies the new settings to the applications using them For example the control panel application uses GConf If setting are used only by a single application Glib utility for ini style files should be used instead Applications should naturally have working default settings Settings should be saved only when the user changes them 14 maemo maemo 4 Quick Start Guide Copyright 2007 Nokia Corporation Malmo 5 3 D Bus 5 3 D Bus For interprocess communications IPC mae
23. l 36 6 maemo maemo 4 Quick Start Guide Copyright 2007 Nokia Corporation TM macmo 2 Terms and Definitions Chapter 2 Terms and Definitions ABI Application Binary Interface provides object code level compatibility API Application Programming Interface provides source code level compati bility applet small application that integrates to Hildon Desktop ARMEL A name that e g Debian uses for the little endian ARM EABI ABI for the ARM architecture devkit Part of the maemo SDK that contains software development tools The SDK contains multiple devkits e g doctools devkit Hildon Application framework used in the maemo platform Developed by Nokia and based on GNOME GTK technologies currently in the process of becoming an upstream project in gnome org Hildon Desktop The main user interface component of the maemo release Chi nook rewrite of maemo desktop Internet Tablet Product category for Internet optimized mobile devices with touchscreen The term was coined by Nokia but is being used more widely to include other devices initfs Initial file system used as the root file system during Linux kernel boot e g for hardware initialization contains kernel modules and utilities for initializing them Mounted after boot to mnt initfs maemo Software platform for mobile devices developed by Nokia based on GNU Linux and GNOME GTK technologies It includes proprietary compo nents t
24. le easy development and hacking Develop ers can make modifications to the platform for instance introducing own kernel mod ules Nokia also hosts an active open source maemo community around the platform maemo org maemo maemo 4 Quick Start Guide 5 Copyright 2007 Nokia Corporation maemo 1 2 Target audience 1 2 Target audience This guide should be interesting reading for any developer with a grasp on GNU Linux and GNOME technologies Thanks to the many links provided to external resources it can even be considered a good starting point for total newcomers with a technical or developer interest The prerequisites for the application developer willing to make the most from this guide is basic GNU Linux C programming knowledge Itis assumed that the most common tools such as gcc are known Much of the maemo user interface development is GTK based If GTK development is not familiar to the reader this document gives starting points to learn the framework No previous maemo or embedded mobile device programming knowledge is required 1 3 Reading instructions The reader should first go through the following two chapters on terms and definitions and maemo architecture After that the rest of the chapters can be read in the order reader is interested in 1 3 1 For the impatient Even though it is not recommended it is possible to start hacking immediately with maemo SDK by following the instructions in the maemo tutoria
25. mo relies heavily on D Bus D Bus makes it possible for programs to export their programming interfaces so that other processes can call them in consistent manner without having to define a custom IPC protocol Us ing these exported APIs is also language agnostic so as long as programming language supports D Bus it can also access the interfaces A maemo specific library called libosso provides helpful wrappers for D BUS com munication It also contains required functionality for every maemo application Ap plications must be initialized using this library With it applications can connect to listen to system hardware state messages such as battery low The library is used also for application state saving and auto save functionality The maemo tutorial 36 provides a good introduction to libosso 5 4 Other system services Maemo platform provides many libraries and APIs for different common tasks Alarm framework and GPS API are described here other relevant services are described later in this document 5 4 1 Alarm Framework The Alarm framework included in maemo gives developers an easy to use an interface for working with all kinds of timed events It provides a consistent user interface audio playing starting the device sending a D BUS signal or executing a file and more The document Using Alarm Interface 73 describes the framework in detail 5 4 5 GPS API The GPS framework in maemo consists of a GPS daemon and a library for c
26. n be browsed anonymously but registration is needed to be able to enter new bug reports or feature requests The same issue management system is used to give feedback about the software running in the device the SDK and the website including its documentation 28 maemo maemo 4 Quick Start Guide Copyright 2007 Nokia Corporation Malmo 11 4 Project Hosting 11 4 Project Hosting The maemo garage 46 is a complete project hosting site for maemo community This is the place where the actual development of maemo applications is preferably done hence the name Garage provides the developers for each project a version control management system wiki issue tracker and forums Application catalog 45 or the Downloads section of the maemo site is meant for end users to be able to easily download and install open source software products on their Internet Tablets The maemo Application Catalog manual 38 has instructions for the maintainer on how to add a new tested application to the application catalog list hopefully incubated first in the garage 11 5 Roadmap and News The maemo community members can keep a track on what is happening now by read ing the news 52 For future plans the roadmap 53 is kept open for avoiding over lapping work and giving visibility where the development effort is going for maemo itself maemo maemo 4 Quick Start Guide 29 Copyright 2007 Nokia Corporation macmo TM BIBLIOGRAPHY Bibliog
27. o application catalog manual http maemo org community application catalog user manual html maemo architecture http maemo org development documentation how tos 4 x maemo architecture html maemo bugzilla http bugs maemo org Maemo connectivity guide http maemo org development documentation how tos 4 x maemo connectivity guide html 42 Maemo debugging guide http maemo org development documentation how tos 4 x maemo debugging guide html 43 maemo developer documentation http maemo org development documentation maemo maemo 4 Quick Start Guide 31 Copyright 2007 Nokia Corporation malmo BIBLIOGRAPHY 44 maemo developers mailing list archive http lists maemo org pipermail maemo developers 45 maemo downloads http maemo org downloads 46 maemo garage http garage maemo org 47 maemo gtk 2 10 http live gnome org Maemo Gtk210Changes 48 maemo home page http maemo org 49 maemo irc channel http maemo org community irc html 50 maemo localization how to http maemo org development documentation how tos 4 x maemo localization how to html 51 maemo mailing lists http maemo org community mailing lists html 52 maemo news http maemo org news 53 maemo roadmap http maemo org intro roadmap html 54 maemo sdk releases http maemo org development sdks 55 maemo wiki http maemo org community wiki 56
28. o make it work on the Nokia Internet Tablets maemo org Developer community web site maintained by Nokia main point of reference for open source and third party developers in general maemo desktop version of main user interface component of the maemo release Bora maemo af desktop Same as maemo desktop maemo maemo 4 Quick Start Guide 7 Copyright 2007 Nokia Corporation malmo 2 Terms and Definitions maemo SDK Software Development Kit to create and port applications to the maemo platform using a PC Nokia Internet Tablet OS maemo platform proprietary applications packaged to an official device image provided by Nokia OSSO Open Source Software Operations Nokia organization developing and integrating software for Internet Tablets rootfs Root file system on the device rootstrap Part of the SDK that contains selected software components from rootfs Rootstrap is the root file system of a target inside Scratchbox Sardine An experimental distribution based on Hildon for maemo primarily of interest for developers who wish to test bleeding edge features that are being developed for future releases of maemo toolchain Part of the SDK that contains ARM cross compilation tools like com piler and linker Maemo SDK releases Mistral maemo 2 0 release Corresponds to the Nokia Internet Tablet SE 2006 version 2 01 2006 26 8 Scirocco maemo 2 1 release including mainly bugfixes and some oth
29. ontrol ling it The maemo connectivity guide 41 gives examples how to use the library in applications maemo maemo 4 Quick Start Guide 15 Copyright 2007 Nokia Corporation TM macmo 6 Multimedia Chapter 6 Multimedia Maemo offers lots of possibilities for multimedia applications Maemo was built with the Internet Tablet devices in mind hardware in this form factor provides a big high resolution touch screen audio input and output video and image capturing through the camera fast network connections for streaming and a digital signal processor for efficient audio and video manipulation For developers there are open programming interfaces to make use of these features apart from directly programming the DSP Preferred way of doing video and audio programming for maemo is using the GStreamer framework and for manipulating static images there are several libraries Interactive multimedia for applications like games can be done using SDL framework The Multimedia Architecture document 59 gives more details on how the components are organized both on the physical device and on the maemo SDK 6 1 GStreamer multimedia framework The main multimedia framework in maemo is GStreamer It is based on the concept of pipelines which are made of multiple elements Elements themselves can be practically anything that do something with a data stream Maemo includes a variety of these elements to support audio and video effects en
30. ploying and distributing 23 4 3 Programming languages o k yc RR KALA NING 24 9 Porting Software 25 9 1 Command line programs llle 25 9 2 Programs with a graphical user interface 25 9 3 Localization lt oes a Kha DN NG 25 10 Quality Considerations 26 10 1 Performance and Responsiveness 26 10 2 Resource USAGE L 5 comas eom ee RR Oe ELS IA 26 10 3 Power consumption k IRR eR LY 26 10 4 Secure Software DESIPO i1 o o ie edt Ember m RUE a 27 11 maemo org 28 Ill DocumenaboN 2 999 xod AR RR 28 1i SUDDORL gt E dote d epos e sie AG Bes dette amp wu e oe 28 ILS Bus Reporte os cesa Rr REOR S ES ER oU 28 114 Project Hosting 22352 bo te toe che babe debe ed 29 11 5 Roadmap and News 2 442646 44 AR ee Oe EUROS 29 maemo maemo 4 Quick Start Guide Copyright 2007 Nokia Corporation TM macmo 1 Introduction Chapter 1 Introduction This document strives to give an overall picture of the maemo platform to developers willing to bring their applications to the Nokia Internet Tablets These mobile devices run a Linux based operating system on ARM architecture The maemo software devel opment kit SDK is currently provided natively for desktop GNU Linux distributions such as Debian and Ubuntu The SDK can also be used in other operating systems through a virtual environment The main focus is to explain the basics needed to create and port maemo com patibl
31. r recording audio should be generally done using GStreamer which provides better performance and a much more flexible API Most of the maemo s computing intensive GStreamer elements are implemented using the device s DSP which greatly enhances their performance Linux kernel also has two lower level audio interfaces ALSA and OSS From these ALSA is supported through a plug in package which is part of the SDK The legacy API OSS is not supported by the kernel but ALSA has an OSS emulation system which works for most purposes For the audio APIs documentation see the GStreamer web site 23 ESound white paper 9 and ALSA project s web site 1 More in depth material is available in the Multimedia Architecture guide 59 6 4 Video Although the framework hides much of the implementation and hardware details it s good for a developer to know what happens beneath the interfaces Video capturing is done via a Linux kernel s Video4Linux API and graphics are displayed using the X Window System Practically all GNU Linux applications rely on these components for video tasks so porting existing applications should be quite effortless and finding support easy Hands on instructions for using capture and output features are given in the Maemo Camera How to 30 6 5 Digital Signal Processor Under the hood Internet Tablets have a dedicated digital signal processor DSP It s design is optimized for tasks like stream coding and audio effects Maemo ha
32. raphy Alsa project s home page http www alsa project org Application binary interface abi for the arm architecture http www arm com products DevTools ABI html Bluez project s home page http www bluez org Busybox http www busybox net Cairo project s home page http cairographics org Cpu transparency how to http maemo org development documentation how tos 4 x cpu transparency how to html Debian the universal operating system http www debian org Debian repository howto http www debian org doc manuals repository howto repository howto Esound white paper http developer gnome org doc whitepapers esd Evolution project s home page http www gnome org projects evolution Extending hildon input methods http maemo org development documentation how tos 4 x extending hildon input methods html Forum nokia http www forum nokia com Gdb The gnu project debugger http sourceware org gdb Gdkpixpuf library http library gnome org devel gdk pixbuf Glib reference manual http developer gnome org doc API glib Gnome mobile http www gnome org mobile Gnome The free software desktop project http www gnome org Gnomevfs api reference http developer gnome org doc API gnome vfs Gnu c library http www gnu org software libc Gnu core utilities http www gnu org software coreutils Gobject reference manual http library gnome org devel
33. rs can reduce the common startup screen coding and concentrate on the real game program ming osso games startup s operating system communication features also offer an interface to make games behave correctly For example it eases the management of full screen mode and exceptional situations such as battery low notification in a unified and user friendly manner See Using Games Start up Screen document 74 for more in depth description and API usage 18 maemo maemo 4 Quick Start Guide Copyright 2007 Nokia Corporation TM macmo 7 Communications Chapter 7 Communications For communications with the outside world maemo platform provides frameworks ranging from Bluetooth file transfer to making video calls This chapter goes through the components important for the maemo application developer 7 1 Acquiring internet access LibConIC is the library that all applications that want to use internet connectivity must use It takes care of e g scanning of available WLAN networks and setting up the IP network after user has selected a connection LibConIC API works together with the maemo connectivity daemon Cd that handles both WLAN and Bluetooth con nections LibConIC and ICd are described more deeply in the maemo connectivity guide 41 72 VoIP Instant Messaging and Presence The Telepathy 69 communications framework provides an unified API for presence messaging and voice video calls The list of supported protocols i
34. s a high level programming support for the DSP in form of GStreamer elements which can decode most of the supported file formats By using the DSP computing load is also taken off from the main processor which greatly enhances system performance and responsivity 6 6 Graphics and Images Maemo includes several libraries for working with images and graphics e Cairo is a library for doing 2D vector graphics It features for example high qual ity vector based graphics support for importing and exporting variety of formats such as SVG PNG PDF and Postscript and bindings for many programming languages maemo maemo 4 Quick Start Guide 17 Copyright 2007 Nokia Corporation malmo 6 7 Games e GDK and GdkPixbuf are the bitmap graphics libraries that GTK is built on They together provide opening and saving bitmap images in JPEG PNG TIFF ICO and BMP formats tight integration with GTK and tools for drawing with graphic primitives Also e g loading of SVG images is supported e For more detailed control over the different image formats there are many more specialized libraries for example libpng libjpeg and libwmf Visit Cairo website 5 for guides tutorials and references GDK s and GdkPixbuf s documentation can be found at GTK4 project s website 25 6 7 Games For game developers maemo offers a common startup and settings screen and a frame work called osso games startup Using this library game developers and porte
35. s long IRC ICQ XMPP Jabber SIP MSN etc The connection manager of Telepathy is expandable and uses D BUS for communication Telepathy usage in maemo is described more deeply in in implementing custom connection managers 32 7 3 Address Book and Contacts The maemo platform features a centralized storage for address book data which is implemented using the Evolution Data Server EDS This allows different applications to effortlessly share contacts in a standardized form so that the user doesn t have to specify them in every program separately For accessing an EDS contact from an application data maemo has the libosso abook library which has powerful widgets that enable consistent user interface for ac cessing and managing the contact information Good reading to quickly start using libosso abook is the Using Maemo Address Book APIs document 75 More in depth information can be found at the Maemo API maemo maemo 4 Quick Start Guide 19 Copyright 2007 Nokia Corporation malmo 7 4 Bluetooth Reference 41 and the Evolution project s web site 10 maemo examples package also includes commented example code that covers using the address book APIs 7 4 Bluetooth A high level API for Bluetooth is offered as part of the maemo connectivity subsystem Using its D BUS API a program can find remote Bluetooth devices such as phones send files over OBEX object push and create pairings with remote devices For these tasks it
36. s recommended for application to use this framework as it not only has a lot simpler API but makes the applications look and behave consistently For Bluetooth operations that aren t supported by the maemo connectivity frame work maemo includes a lower level BlueZ D BUS API which is also the main Blue tooth interface for all Linux systems The BlueZ API has features for practically all aspects of Bluetooth systems and as a consequence its a lot more complex than the higher level Maemo Connectivity subsystem s offerings The Maemo Connectivity Guide 41 describes the high level D BUS API and its usage More information about the BlueZ API can be found at BlueZ web site 3 The maemo example package also includes example code about both libraries 7 4 4 OBEX Bluetooth devices use OBEX protocol to exchange data objects Maemo includes li braries to help working with this protocol For OBEX FTP the easiest way is to use GnomeVFS s OBEX backend For more granular control there is libgwobex which GnomeVFS uses in its implementation and even more low level interface is the OpenOBEX library More about GnomeVFS is written in this document s GnomeVFS section Maemo Connectivity Guide 41 has chapters for libgwobex and OpenOBEX For libgwobex API see Maemo API Reference 37 and lots of information about OpenOBEX can be found at the project s web site 60 20 maemo maemo 4 Quick Start Guide Copyright 2007 Nokia Corporation TM macmo 8 Dev
37. sktop software to the mobile maemo environment Earlier in this guide the basic tools that ease cross compilation and help coping with the GNU autotools were explained This chapter gives pointers to the relevant guides focusing on the differences in the application programming and user interfaces 9 1 Command line programs Porting software with no user interface in most cases is trivial and straight forward First the source code of a program is unpacked to the home directory of a Scratchbox user Second inside ARMEL target configure and make are run Then the compiled program can be tested on the device Finally the software needs to be packaged 9 2 Programs with a graphical user interface The porting of an application that uses GTK for its graphical user interface begins the same way as above In addition to this the user interface part needs to be refactored to use Hildon instead of directly using GTK Dependencies to GNOME components if any need to be removed or replaced with corresponding maemo SDK components If the application uses any components not available in the maemo SDK these must be also ported by the developer Applications that do not use GTK and instead use e g SDL need more work The first thing that is easily noticed that the virtual keyboard is missing because the Hildon Input Method is not available A user of the application cannot interact with the application The maemo 4 0 porting guide 35 goes into the nece
38. ssary details of porting an existing GTK application to maemo environment 9 3 Localization The localization of maemo applications is done using the common gettext package The translating of an application to different languages is described in detail in the Localization How to 50 maemo maemo 4 Quick Start Guide 25 Copyright 2007 Nokia Corporation TM macmo 10 Quality Considerations Chapter 10 Quality Considerations The maemo developer needs to take care many details when developing a good quality application for an embedded device Compared to the desktop Linux a developer needs to be more careful with performance resource usage power consumption security and usability issues The Quality Awareness project 64 provides a generic test plan for developers to help them to create a good quality software 10 1 Performance and Responsiveness The user wants to be in control the device must be responsive at all times and give appropriate feedback The UI responsiveness can be achieved e g in the three follow ing ways First using process events by showing a banner and blocking the UI while operating Second option would be to slice the operation into parts while updating e g a progress bar Thirdly threading can be achieved with the help of GLib but this is in creasingly hard to implement and debug For time consuming tasks the second option is recommended If the operation takes only a second or two the first
39. the host provided for convenience and speed They are always preferred over target tools and transparently for example cross compile appli cations to the target architecture Host tools consist of devkits and toolchains A toolchain provides the minimal set of tools for compiling binaries for the target One and only one toolchain must be selected for every Scratchbox target CPU transparency methods take care of running the applications on an emulator target device or directly on the host transparently to the user The available CPU trans parency methods come from a special devkit called cputransp For each of maemo SDK s predefined targets a CPU transparency method is selected and defined A toolchain is a collection of tools used to produce binaries for the target environ ment In addition to a compiler gcc it contains a linker d and other binutils such as strip objdump and strings A devkit is a collection of tools native to the host A toolkit can be selected or disabled for a target An example of a devkit is doctools devkit which provides tools like doxygen for building documentation A rootstrap is a root file system for the target device Maemo SDK provides root file systems for both targets X86 and ARMEL inside Scratchbox Note that the user s home directory is shared for all targets The tmp directory is shared for all targets and also with host From Scratchbox s point of view Maemo SDK is a set of preconfigured targets an
40. to a great extent Compared to a GNOME desktop from a user interface point of view Hildon is designed to provide a new desktop for mobile embedded devices Therefore it for example uses a lighter window manager called Matchbox 57 4 1 Hildon desktop The end user s desktop experience on Nokia Internet Tablets is provided by the Hildon Desktop that is based on Hildon The latter provides several libraries to interface with the desktop environment UI elements and services Hildon framework s main UI elements are separated to four categories and all of them can be extended with plug ins e Hildon Home is the root desktop which can be customized by Hildon home applets e Hildon Status bar provides area for information and quick access items used mainly to communicate device status changes e Hildon Task Navigator plugins implement the top level desktop menus e Hildon Control Panel is a general interface for application configuration and is extended by control panel plugins See Hildon Desktop Plugins How to 77 for more detailed information GUI applications in maemo usually have one or more HildonWindows which are the top level application windows They can include a standardized menubar and a toolbar The Hildon framework also includes other auxiliary widgets and services spe cialized for the Hildon environment Examples of these are the Hildon FM library for file system dialogs and widgets HildonBanner for displaying notifications for
41. tored via GConf and an XML parser API is available Application The figure above illustrates the most crucial components and their dependencies that the maemo application developer must deal with These components are explained in more detail in the next chapters 10 maemo maemo 4 Quick Start Guide Copyright 2007 Nokia Corporation Malmo 3 4 maemo compared to desktop Linux distributions 3 4 maemo compared to desktop Linux distributions Ubuntu 71 is a popular Debian based Linux distribution for the ordinary desktop The Ubuntu wiki 70 lists the key differences of Ubuntu and Debian As one of the design principles of maemo has been to be as close as a traditional desktop Linux as feasible here the differences between Debian Ubuntu and maemo are explained in detail 3 4 1 CPU architecture differences Where as Debian supports multiple CPU architectures Ubuntu s set is a bit more re stricted Compared to that maemo is an embedded ARM EABI 2 distribution Maemo is also cross compiled instead of natively compiled like Debian or Ubuntu Maemo also uses different versions of toolchains GCC glibc 19 etc than Ubuntu or Debian for ARM feature support and maturity differences between architectures 3 4 2 Security model differences Instead of a multi user system such as a traditional Linux desktop maemo is considered a single user desktop system The security model in maemo is focused on protecting the user from remote att
Download Pdf Manuals
Related Search