Platform Leadership through System Interfaces: A Study of Application Programming Interfaces for Mobile Operating Systems by Ashok Chakravarthy Mandala Bachelor of Engineering, Computer Science Birla Institute of Technology and Science, Pilani, India Submitted to the System Design and Management Program in Partial Fulfillment of the Requirements for the Degree of Master of Science in Engineering and Management at the Massachusetts Institute of Technology February 2007 © 2007 Ashok Mandala All rights reserved The author hereby grants to MIT permission to reproduce and to distribute publicly paper and electronic copies of this thesis document in whole or in part. Signature of Auiithnr - Ashok Mandala System Design and Management Program February 2007 Certified by Michael A. Cusumano Thesis Supervisor Sloan School of Management Certified by Patrick Hale MASSACHUSETTS INSTITUT OF TEO-NOLOGY Director System Design and Management Program MAY 0 6 2008 ARCHGES LIBRARIES Platform Leadership through System Interfaces: A Study of Application Programming Interfaces for Mobile Operating Systems By Ashok C. Mandala Submitted to the System Design and Management Program on January 19, 2007 in Partial Fulfillment of the Requirements for the Degree of Master of Science in Engineering and Management ABSTRACT The Smart Mobile device industry is witnessing rapid growth with the increased convergence of voice-centric mobile phones and data-centric personal digital assistant systems. Improving capabilities in device hardware have allowed development of complex user interfaces, multimedia and communication capabilities on these devices. Modem Mobile Operating Systems manage this complexity in the mobile device by administering hardware resources and providing a platform for development of new consumer and enterprise applications. This thesis studies the architecture, design goals and services offered by the three major mobile operating systems - Palm OS, Symbian OS and Windows Mobile. The Mobile Operating Systems studied in this thesis differ in their architectures, services and programming interfaces offered to application software developers, independent hardware vendors and OEM licensees. Their design reflects the OS vendor's strategy toward the mobile platform which is decipherable based on a study of the OS architecture and application programming interface. Three conclusions are made based on this study - each of them suggests a strategy that the vendor has attempted to use to gain platform leadership through product architecture and degree of openness of interfaces. Thesis Supervisor: Michael A. Cusumano Title: Sloan Management Review Distinguished Professor of Management, Technological Innovation & Entrepreneurship. -1- Table of Contents TA BLE OF C O N TEN TS ............................................................................................................................. 2 LIST O F FIG U RES ...................................................................................................................................... 4 C H A PTER 1 .................................................................................................................................................. 5 1.1 INTRODUCTION ..................................................................................................................................... 5 1.2 O RGANIZATION OF THE THESIS ............................................................................................................. 6 C H A PTER 2 .................................................................................................................................................. 7 2.1 PALM OPERATING SYSTEM - HIGH LEVEL ARCHITECTURE ............................................................... 7 User Interface.......................................................................................................... ..................... 8 Mem ory Managem ent.............................................................................................. ........................ 10 Object Exchange ................................................................................................................................. 13 Infrared (IR) Library........................................................................................................................... 13 Serial Comm unications.......... ............................................................................................................ 14 Bluetooth ............................................................................................................................................. 14 Network Library .................................................................................................................................. 15 Telephony ............................................................................................................................................ 16 2.2 SYMBIAN OPERATING SYSTEM - HIGH LEVEL ARCHITECTURE ................................. ....................... 17 Base API................................................................................................................ .......................... 20 H andles ............................................................................................ ............................................ 21 Inter-Process Comm unication............................................................................................................. 22 Sym bian Client-ServerFram ework..................................................................................................... 24 Mem ory Managem ent.............................................................................................. ........................ 24 ProcessM odel........................................................................................................ ......................... 26 File System .......................................................................................................................................... 27 Bluetooth ............................................................................................................................................. 27 Communications Infrastructure................................... ..................... 28 Infrared Comm unications.................................................................................................................... 29 Messaging ........................................................................................................................................... 30 Graphics................................................... ......................................................... 30 Multim edia .......................................................................................................................................... 33 Security............................................................................................................. 34 Telephony ............................................................................................................................................ 35 Application Engines ............................................................................................................................ 37 Text H andling................................................................................................................................... 37 Base UI Framework............................................................................................................................ 37 2.3 WINDOWS MOBILE OPERATING SYSTEM - HIGH LEVEL ARCHITECTURE............................................ 38 K ernel.............................................................................................................. 41 Mem ory Managem ent.............................................................................................. ........................ 43 UserInterface................................................................................................................................... 45 N etworking .......................................................................................................................................... 48 Infrared Comm unications.............................................................. ........................... 50 Bluetooth ............................................................................................................................................. 51 Telephony ............................................................................................................................................ 52 Security.................................................. ........................................................... 53 C H A PTER 3 ................................................................................................................................................ 55 3.1 PALM O S EVOLUTION ................................ ........................................................ ........................ 55 3.2 SYM BIAN O S EVOLUTION ................................ ................................................................................... 62 3.3 W INDOW S CE EVOLUTION ................................ ................................................................................. 68 3.4 A NALYSIS ..........................................................................................................................................