1 / 43

Understanding Code Mobility

Understanding Code Mobility Sachin Chouksey H. Qiu Xiong Distributed Applications Problems with traditional approaches Technologies,architectures,methodologies. Large scale distributed settings. Fail to provide Configurability Scalability Customizability Code Mobility

libitha
Télécharger la présentation

Understanding Code Mobility

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Understanding Code Mobility Sachin Chouksey H. Qiu Xiong

  2. Distributed Applications • Problems with traditional approaches • Technologies,architectures,methodologies. • Large scale distributed settings. • Fail to provide • Configurability • Scalability • Customizability

  3. Code Mobility • An emerging research field. • However • Lack of standard terms and concepts. • Difficult to assess and compare existing approaches. • Paper presents conceptual framework. • Classification • Technologies • Design Paradigms • Applications.

  4. Development Environment • Computer Networks • Increasing size and performance • Pervasive • Ubiquitous • Mobile computing • World Wide Web

  5. Problems • Size of Networks (Scalability) • Wireless Connectivity • Dynamic topologies • Large scale diffusion into society • Customizability • Flexibility • Extensibility • Current proposed Approaches

  6. Similar Approaches • Remote Job submission • Process Migration • Object Migration BUT THESE DO NOT SCALE

  7. How is code mobility different ? • Internet-scale • Location Aware • Programmer controlled mobility • Mobility for • Load Balancing • Service Customization • Dynamic extension and application functionality • Autonomy • Fault tolerance • Disconnected Operation

  8. 3D Classification • Technologies • Languages & systems that provide mechanisms • Used in implementation stage by developer • Design Paradigms • Architectural styles used • C2, P2P, Client-Server • Application Domains • Classes of applications • E-Commerce, Distributed information retrieval

  9. Mobile Code Technologies • Traditional Distributed System Layers • Core Operating System • Network Operating System • True Distributed System • For Code Mobility • Computational Environments (CE) • CE retains identity of the host • Dynamically relocate components on different hosts • CE hosts Execution units (EUs) and resources

  10. Mobility Mechanisms • EU = Code Segment + Execution State + Data Segment • EU moves from CE to CE • Orthogonal mechanisms • Code and execution state mobility • Data space management

  11. Code and Execution State Mobility • Strong mobility • Migration • Proactive / Reactive • Remote cloning • Weak mobility • Fetch / Ship • Stand alone code / code fragment • Synchronous / Asynchronous

  12. Data Space Management • Rearrange EU-Resource bindings after migration • Resource = <I,V,T> • Bindings • By Identifier • By Value • By Type • Bindings constrain the data space management mechanisms • Resource Relocation • Binding reconfiguration

  13. Agent Tcl Ara Facile Java Java Aglets M0 Mole Obliq Safe-Tcl Sumatra TACOMA Telescript Current Mobile Code Technologies

  14. Design Paradigms • Design paradigms, or architectural styles, define architectural abstractions and reference structures that may be instantiated into actual software architectures

  15. Why Design Paradigms? • The goal of design is the creation of a software architecture, which can be defined as the decomposition of a software system in terms of software components and interactions among them • Software architectures with similar characteristics can be represented by design paradigms

  16. Describe Design Paradigms • Design paradigms are described in terms of interaction patterns that define the relocation of and coordination among the components needed to perform a service

  17. Components • Components are the constituents of a software architecture. • They can be further divided into: • Code components • Resource components • Computational components

  18. Interactions • Interactions are events that involve two or more components, e.g., a message exchanged among two computational components

  19. Sites • Sites host components and support the execution of computational components • A site represents the intuitive notion of location

  20. Design Paradigms • Client-Server (CS) • Remote Evaluation (REV) • Code on Demand (COD) • Mobile agent (MA)

  21. Comparison of the Paradigms

  22. Outline • Add the 1st person’s • Design Paradigms • Add the 3d person’s

  23. Design Paradigms • Design paradigms, or architectural styles, define architectural abstractions and reference structures that may be instantiated into actual software architectures

  24. Why Design Paradigms? • The goal of design is the creation of a software architecture, which can be defined as the decomposition of a software system in terms of software components and interactions among them • Software architectures with similar characteristics can be represented by design paradigms

  25. Describe Design Paradigms • Design paradigms are described in terms of interaction patterns that define the relocation of and coordination among the components needed to perform a service

  26. Components • Components are the constituents of a software architecture. • They can be further divided into: • Code components • Resource components • Computational components

  27. Interactions • Interactions are events that involve two or more components, e.g., a message exchanged among two computational components

  28. Sites • Sites host components and support the execution of computational components • A site represents the intuitive notion of location

  29. Design Paradigms • Client-Server (CS) • Remote Evaluation (REV) • Code on Demand (COD) • Mobile agent (MA)

  30. Comparison of the Paradigms

  31. Mobile Code Applications(1) • They are still immature and lack of suitable methodologies. • The benefits of mobile code are appealing.(Mobile agent systems, Internet agents) • It is important to distinguish the implementation process and the paradigm.

  32. Mobile Code Applications(2) Benefits: 1. Service Customization- The interfaces or services are are not statically defined. 2. Supporting more flexible software deployment and maintenance. 3. Automatic software upgrade without human interaction on the client side.

  33. Mobile Code Applications(3) Benefits: 4. Autonomy of application components. - heterogeneous communication infrastructure complexes the network and requires autonomic design. Two solutions: Or put more operations on the clients Put more operations on the server

  34. Mobile Code Applications(4) Benefits: 5. The fault tolerance is much improved in Mobile code than the conventional client-server system. 6. A new protocol is needed to enhance the code migration among distributed systems. 7. Date management flexibility and protocol encapsulation.

  35. Mobile Code Applications(5) Application Domains for Mobile Code • Distributed Information Retrieval • Active Documents • Advanced Telecommunication Services • Remote Device Control and Configuration • Workflow Management and Cooperation • Active Networks • Electronic Commerce

  36. A Case Study In Network Management (1) • Determine if mobile code is suitable for the specific application first. • Identify the corresponding paradigms. • Analyze the tradeoff for each application functionality. • Select the technology to implement the application according to the tradeoff.

  37. A Case Study In Network Management (2) The network congestion traffic problem: 1. The problem to solve: Decentralizing Network Traffic -Both SNMP and CMIP are inefficient while the network heavy congestion. - Some modifications have been made to solve the problem, such as the SNMPv2 with the proxy agents and the Remote Monitoring.

  38. A Case Study In Network Management (3) 2. Identifying the Design Paradigms -REV paradigm can be used, which will pack up all the SNMP operations and send them on the device for the local interaction. -Only the useful target value will be sent back after execution. -The capability to retain the state across several hops will also make the whole system more autonomic.

  39. A Case Study In Network Management (4) 3. Evaluating the Design Tradeoffs (details will not be discussed) -The mobile code is only convenient when a set of SNMP instructions can be “packed” efficiently into mobile code. -The choice of the paradigm is constrained by the actual values for the parameters of the application.

  40. A Case Study In Network Management (5) Choosing the Implementation Technology -In principle, design paradigms and implementation are orthogonal. Sometimes, they are different. -We also have to think about the global application development when we implement a given functionality inside it.

  41. Summary and Conclusions • Mobile code is a promising solution for the design and implementation of large scale distributed applications • Little attention has been paid to the formulation of a sound conceptual framework for code mobility • Three classes of concepts in a proposed conceptual framework: applications, design paradigms and technologies

  42. Strengths and Weaknesses • Systematically presenting knowledge about code mobility: motivations, concepts, principles, approaches, technologies, etc., therefore, providing a complete image • Expounding is vivid with metaphor

  43. Relevance to Embedded Systems • Many embedded systems are resource-constrained • Requirements to them are higher and higher • Code mobility technology providing a possible solution • Many embedded systems are real-time systems that can not be stopped to do operations such as update

More Related