Hello Friends,
Today we will discuss about "Symbian OS".

Introduction
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* Symbian OS is an operating system, designed for mobile devices, with associated libraries, user interface frameworks and reference implementations of common tools, produced by Symbian Ltd. It is a descendant of Psion's EPOC and runs exclusively on ARM processors.

* Symbian is currently owned by Ericsson, Panasonic, Siemens AG, Nokia, and Sony Ericsson. Whilst BenQ has acquired the mobile phone subsidiary of Siemens AG the Siemens AG stake in Symbian does not automatically pass to BenQ - this will need the approval of the Symbian Supervisory Board.

* History ( 1980 - 2006)

+ In 1980, Psion Software was founded by David Potter.

+ EPOC16. Psion released several Series 3 devices from 1991 to 1998 which used the EPOC16 OS, also known as SIBO.

+ EPOC OS Releases 1–3. The Series 5 device, released in 1997, used the first iterations of the EPOC32 OS.

+ EPOC Release 4. Oregon Osaris and Geofox 1 were released using ER4.

+ In 1998, Symbian Ltd. was formed as a partnership between Ericsson, Nokia, Motorola and Psion, to explore the convergence between PDAs and mobile phones.

+ EPOC Release 5 a.k.a. Symbian OS v5. Psion Series 5mx, Series 7, Psion Revo, Psion Netbook, netPad, Ericsson MC218, and the Ericsson R380 were released in 1999 using ER5.

+ ER5u a.k.a. Symbian OS v5.1. u = Unicode. The first phone, the Ericsson R380 was released using ER5u in 2000. It was not an 'open' phone - software could not be installed. Notably, a number of never released Psion prototypes for next generation PDAs, including a Bluetooth Revo successor codenamed Conan were using ER5u.

+ Symbian OS v6.0 and v6.1. Sometimes called ER6. The first 'open' Symbian OS phone, the Nokia 9210, was released on 6.0.

+ Symbian OS v7.0 and v7.0s. First shipped in 2003. This is an important Symbian release which appeared with all contemporary user interfaces including UIQ (Sony Ericsson P800, P900, P910, Motorola A925, A1000), Series 80 (Nokia 9300, 9500), Series 90 (Nokia 7710), Series 60 (Nokia 6600, 7310) as well as several FOMA phones in Japan.

+ In 2004, Psion sold its stake in Symbian.

+ Also in 2004, the first worm for mobile phones using Symbian OS, Cabir, was developed, which used Bluetooth to spread itself to nearby phones. See Cabir and Symbian OS threats.

+ Symbian OS v8.0. First shipped in 2004, one of its advantages would have been a choice of two different kernels (EKA1 or EKA2). However, the EKA2 kernel version did not ship until SymbianOS v8.1b. The kernels behave more or less identically from user-side, but are internally very different. EKA1 was chosen by some manufacturers to maintain compatibility with old device drivers, whilst EKA2 offered advantages such as a hard real-time capability.

+ Symbian OS v8.1. Basically a cleaned-up version of 8.0, this was available in 8.1a and 8.1b versions, with EKA1 and EKA2 kernels respectively. The 8.1b version, with EKA2's single-chip phone support but no additional security layer, was popular among Japanese phone companies desiring the real-time support but not allowing open application installation.

+ Symbian OS v9.0. This version was used for internal Symbian purposes only. It was de-productized in 2004.

+ Symbian OS has generally maintained reasonable binary compatibility. In theory the OS was BC from ER1-ER5, then from 6.0 to 8.1b. Substantial changes were needed for 9.0, related to tools and security, but this should be a one-off event. The move from requiring ARMv4 to requiring ARMv5 did not break backwards compatibility.

+ A Symbian developer proclaims that porting from Symbian 8.x to Symbian 9.x is a more daunting process than Symbian says.

+ Symbian OS v9.1 released early 2005. Improvements in the OS mean that applications and content, and therefore a developers investment, are better protected than ever. The new ARM EABI binary model means developers need to retool and the security changes mean they may have to recode. S60 3rd Edition phones have Symbian OS 9.1. Sony Ericsson is shipping the M600i based on Symbian OS 9.1 and should ship the P990 in Q3 2006.

+ Symbian OS v9.2 released Q1 2006. Support for Bluetooth 2.0 (was 1.2) and OMA Device Management 1.2 (was 1.1.2). S60 3rd Edition Feature Pack 1 phones have Symbian OS 9.2.

+ Symbian OS v9.3 released on 12 July 2006. Upgrades include native support for Wifi 802.11, HSDPA, and Vietnamese language support.

* A common question is whether Symbian OS is "open". It is not open in the sense of Open Source software - the source code is not publicly available. However, nearly all the source code is provided to Symbian OS phone manufacturers and many other partners. Moreover, the APIs are publicly documented and anyone can develop software for Symbian OS. This contrasts with traditional embedded phone operating systems, which typically cannot accept any aftermarket software except Java applications.

* Symbian is also open in terms of the Open Standards it supports.

* There are a number of smart phone user interface platforms based on Symbian OS, including open platforms UIQ, Nokia's Series 60, Series 80 and Series 90 and closed platforms such as that developed for NTT DoCoMo's FOMA handsets. This adaptability allows Symbian OS to be used on smart phones with a variety of form factors (e.g. clam-shell or "monoblock"/"candybar", keypad- or pen-driven).

* Symbian OS, with its roots in Psion Software's EPOC is structured like many desktop operating systems, with pre-emptive multitasking, multithreading, and memory protection.

Symbian OS's major advantage is the fact that it was built for handheld devices, with limited resources, that may be running for months or years. There is a strong emphasis on conserving memory, using Symbian-specific programming idioms such as descriptors and a cleanup stack. Together with other techniques, these keep memory usage low and memory leaks rare. There are similar techniques for conserving disk space (though the disks on Symbian devices are usually flash memory). Furthermore, all Symbian OS programming is event-based, and the CPU is switched off when applications are not directly dealing with an event. This is achieved through a programming idiom called active objects. Correct use of these techniques helps ensure longer battery life.

* All of this makes Symbian OS's flavor of C++ very specialized, with a steep learning curve. However, many Symbian OS devices can also be programmed in OPL, Python, Visual Basic, Simkin, and Perl - together with the Java ME and PersonalJava flavors of Java.

* Symbian OS competes with other mobile operating systems, such as Windows Mobile, Palm OS, and Linux. It also competes with the embedded operating systems used on lower-end phones, such as NOS and OSE, which tend to be maintained by the phone companies themselves. Symbian OS' major advantage over these embedded operating systems is its modularity - there is runtime linking between dynamically linked shared libraries (DLLs, see dynamic linking) on the device, and an emphasis on plug-in architectures. This makes complex phones quicker to develop, though this is sometimes offset by the complexity of Symbian OS C++ and the awkwardness of going to another company for an OS (instead of doing it in-house).

* The advantages over other 'open' OS competitors (such as Linux and Windows Mobile, the latter is not Open Source) are more debatable. Phone vendors and network operators like the customizability of Symbian OS relative to Windows. This customizability, though, makes integrating a Symbian OS phone more difficult. It's possible that Linux goes too far in the other direction, and is simply too hard to make a phone from at the moment. Symbian OS's ground-up design for mobile devices should make it more power- and memory-efficient, as well as being flexible.

* At its lowest level sit the base components of Symbian OS. This includes the kernel (EKA1 or EKA2), along with the user library which allows user-side applications to request things of the kernel.

* Symbian OS has a microkernel architecture, which means that the minimum necessary is within the kernel. It does contain a scheduler and memory management, but no networking or file system support. These things are provided by user-side servers. The base layer includes the file server, which provides a fairly DOS-like view of the file systems on the device (each drive has a drive letter, and backslashes are used as the directory delimiter). Symbian OS supports various file system types including FAT32 and Symbian OS-specific NOR flash filing systems. The file system is generally not exposed to the user through the phone user interface.

* Immediately above base is a selection of system libraries. These take all shapes and sizes, including for example character set conversion, a DBMS database, and resource file handling.

* Further up, the software is not so readily arranged into a stack.

* There is a large networking and communication subsystem, which has three main servers - ETEL (EPOC telephony), ESOCK (EPOC sockets) and C32 (responsible for serial communication). Each of these has a plug-in scheme. For example ESOCK allows different ".PRT" protocol modules, implementing different types of networking protocol scheme. There's lots of stuff relating to short-range communication links too, such as Bluetooth, IrDA and USB.

* There's also a large amount of user interface code. Even though the user interfaces themselves are maintained by other parties, the base classes and substructure ("UIKON") for all UIs are present in Symbian OS, along with certain related servers (for example, a view server which controls transitions between different phone user interface screens). There's a lot of related graphics code too - such as a window server and a font and bitmap server.

* An application architecture provides for standard application types, embedding, and file and data recognition. There is also a selection of application engines for popular smartphone applications such as calendars, address books, and task lists. A typical Symbian OS application is split up into an engine DLL and a graphical application - the application being a thin wrapper over the engine DLL. Symbian OS provides some of these engine DLLs.

* There are, of course, many other things that don't yet fit into this model - for example, SyncML, Java ME providing another set of APIs on top of most of the OS and multimedia. Quite a few of these things are frameworks, and vendors are expected to supply plug-ins to these frameworks from third parties (for example, Helix player for multimedia codec’s). This has the advantage that the APIs to such areas of functionality are the same on many phone models, and that vendors get a lot of flexibility, but means that phone vendors need to do a great deal of integration work to make a Symbian OS phone.

* Symbian OS device manufacturers also get supplied with an example user interface layer called TechView. This looks very similar to the user interface from a Psion Series 5 personal organizer, so isn't particularly similar to any given phone user interface, but provides a basis to start customization. It is also the environment in which a lot of Symbian OS test code and example code runs.

How to develop on SymbianOS Platform
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* There are multiple platforms, based upon Symbian OS, that provide an SDK for application developers wishing to target a Symbian OS device - the main ones being UIQ, Series 60, etc.
* Individual phone products, or families, often have SDKs or SDK extensions downloadable from the manufacturer's website too.
* The SDKs contain documentation, the header files and library files required to build Symbian OS software, and a Windows-based emulator ("WINS").
* Up until Symbian OS version 8, the SDKs also included a version of the GCC compiler (a cross-compiler) required to build software to work on the device. Don’t worry It means that you can use other Commercial (Like ARM Realview)/ GNU with SDK.
* Symbian OS 9 uses a new ABI and so requires a new compiler - a choice of compilers is available including a new version of GCC. In terms of SDKs, UIQ Technology now provides a simplified framework so that the single UIQ SDK forms the basis for developing on all UIQ 3 devices, such as the Sony Ericsson P990 and Sony Ericsson M600.
* Symbian C++ programming is commonly done with a commercial IDE. Previously, Visual Studio was common, but for current versions of Symbian OS, a Symbian-specific version of CodeWarrior is favoured.
* The CodeWarrior tools will be replaced during 2006 by Carbide.c++, an Eclipse-based IDE developed by Nokia. It is expected that Carbide.c++ will be offered in different versions: a free version may allow users to prototype software on the emulator for the first time in a free product. (In Symbian History)
* Visual Basic, VB.NET, and C# development for Symbian can be accomplished through AppForge Crossfire, a plugin for Microsoft Visual Studio.
* There's also a version of a Borland IDE for Symbian OS. Symbian OS development is also possible on Linux and Mac OS X using tools and techniques developed by the community, partly enabled by Symbian releasing the source code for key tools. A plugin that allows development of Symbian OS applications in Apple's Xcode IDE for Mac OS X is available.
* Once developed, Symbian OS applications need to find a route to customers' mobile phones. They are packaged in SIS files which may be installed over-the-air, via PC connect or in some cases via Bluetooth or memory cards. An alternative is to partner with a phone manufacturer to have the software included on the phone itself.
* The SIS file route will be a little more difficult from Symbian OS 9, because any application wishing to have any capabilities beyond the bare minimum must be signed via the Symbian Signed program.
* Java ME applications for Symbian OS are developed using standard techniques and tools such as the Sun Java Wireless Toolkit (formerly the J2ME Wireless Toolkit). They are packaged as JAR (and possibly JAD) files. Both CLDC and CDC applications can be created with NetBeans.
* Other tools include SuperWaba, which can be used to build Symbian 7.0 and 7.0s programs using Java.

Useful links
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* SDK Download: http://www.symbian.com/
* Information: http://www.newlc.com/
* Symbian Forum: http://forum.newlc.com/

Coming up
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* I will Post Some more posts on Symbian in coming days.

Do write comments about this post or write to me at [skumar.brewdev@yahoo.com]

Thanks.
Sunil Kumar
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