Mobile Code technologies Component Component Component Component Component Computational Computational omputauonal Environment Environment Environment Network Network Network Operating system Operating System Operating system Core Operating System Core Operating System Core Operating System 2021/24 Institute of Computer Software, Nanjing University
2021/2/4 Institute of Computer Software, Nanjing University 11
Comparison Traditional Systems True Distributed System(TDS)provide network transparency Distributed components are perceived as local Computational Environments(CE) Underlying structure of the network is made manifest to the users Provides capability to relocate code dynamically → Execution units(EU) → Resources 2021/24 Institute of Computer Software, Nanjing University
Traditional Systems True Distributed System (TDS) provide network transparency Distributed components are perceived as local MCSs Computational Environments (CE) Underlying structure of the network is made manifest to the users. Provides capability to relocate code dynamically → Execution units (EU) → Resources 2021/2/4 Institute of Computer Software, Nanjing University 12
Components of CE Execution Units(threads) Code segment 4 Execution state (stack and instruction pointer) Executing Unit Resource 目目 Data space Computational Environment Resources( Files, operating system variable) 2021/24 Institute of Computer Software, Nanjing University
2021/2/4 Institute of Computer Software, Nanjing University 13 Execution Units (Threads) Resources (Files, operating system variable)
Classification of Mobility Mechanisms Code and execution state mobility Strong mobility Supported by: migration and remote cloning Weak mobility Supported by: Code shipping and Code Fetching 2021/24 Institute of Computer Software, Nanjing University
Code and Execution State Mobility → Strong mobility Supported by: migration and remote cloning →Weak mobility Supported by: Code shipping and Code Fetching 2021/2/4 Institute of Computer Software, Nanjing University 14
Code and execution state Strong mobility - Migration mechanisms management Reactive Remote cloning— Proactive Reactive Weak mobility Code shipping Stand-alone Synchronous Asynchronous-Immediate Deferred Code Synchronous Code fetchin Stand-alone code Synchronous synchronous-TImmedlate ragment Synchronous Asynchronous Immediate ata spa ding removal management Network reference By copy By move 2021/24 Institute of Computer Software, Nanjing University 15
2021/2/4 Institute of Computer Software, Nanjing University 15