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Disclaimer:This presentation is prepared by trainees of baabtra as a part of mentoring program. This is not official document of baabtra –Mentoring PartnerBaabtra-Mentoring Partner is the mentoring division of baabte System Technologies Pvt . Ltd
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Introduction
• Operating System: provide common services to applications: IO, communication, storage.
• With multiprogramming: include abstracting shared resource.
• Local Area Network: birth of Network OS to provide access to network resources.
• We need similar services for Wide Area Network distributed applications.
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Introduction (cont)
• World Wide Web is the most widely used applications on the Internet.
• Web made geographically distributed read-only data easy to use, but geographically distributed computing resources are not.
• The result is that wide area applications that require access to remote CPU cycles, memory, or disk must be programmed in an ad hoc and application-specific manner.
• =>Increase complexity!
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Introduction (cont)
• WebOS: a framework for supporting applications that are geographically distributed, highly available, incrementally scalable, and dynamically reconfiguring.
• WebOS includes:– Resource discovery– A global namespace– Remote process execution– Resource management– Authentication and security
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– To provide the best overall system performance, client applications must be able to dynamically locate the server able to deliver the highest quality of service.
– Resource discovery includes mapping a service name to multiple servers, an algorithm for balancing load among available servers, and maintaining enough state to perform fail-over if a server becomes unavailable.
– These operations are performed through Smart Clients.
Resource Discovery
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– To support replication and wide-scale sharing, WebOS provides a cache coherent wide area file system.
– WebOS extends to wide area applications running in a secure HTTP name space the same interface, caching, and performance of existing distributed file systems.
Wide Area File System
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– To support applications operating across organizational boundaries, WebOS defines a model of trust providing both security guarantees and an interface for authenticating the identity of principals.
– A key enabling feature is fine-grained control of capabilities provided to remote processes executing on behalf of principals.
Security and Authentication
• WebOS Security model Step 1: users transfer some portion of their access rights to webOS server when attempting to access a remote resource
Step 2: WebOS servers communicate using SSL
Step 3: The remote server checks if the proper credentials are held in local ACL’s
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– In WebOS, executing a process on a remote node should be as simple as the corresponding local operation.
– The underlying system is responsible for authenticating the identity of the requester and determining if the proper access rights are held.
Process Control
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Global Namespace
• Many applications share state and transfer control using network communication
• Parallel applications use shared memory or message passing
• Using frameworks: global cache coherent file systems for communication and synchronization
• Requirements: authentication, security and fault tolerance
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Global Namespace
• provides a unified way of mapping multiple NFS(Network File System is a file sharing protocol used on Unix systems ) or CIFS(Common Internet File System is a protocol developed by Microsoft) presented resources under a single Hierarchical logical data structure
• allows resources which are not physically located to participate in this structure
• allow data to be replicated and moved around the enterprise without compromising data access
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WebOS Applications
• Internet Chat:- The Internet Chat application is a simple client and server application. - The Chat Client stack contains the scripts for the client, and would be distributed to each person on the network.- The Chat Server stack contains the scripts for the chat server.
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WebOS Applications(cont.)
• Internet Chat(cont.):- The initial implementation:
+1200 lines of Java code in the client+4200 lines of C++ code in the server.
- By using WebFS :+ 850 lines in the client+ The WebFS interface entirely replaced
the 4200 lines of chat server code.
• Advantages 1 occupies little hard disk space 2 occupy small CPU resources 3 can be obtained at any OS with web browser
• Disadvantages that needs to be improved 1 easy to be hacked 2 can not be obtained offline 3 can not program on the local hardware so USB disk and CDROM can not be used. 4 more bandwidth is needed for multiple programs to run
simultaneously
several popular Web OS• YouOS EyeOS
• Desktop2
• If this presentation helped you, please visit our page facebook.com/baabtra and like it. Thanks in advance.
• www.baabtra.com | www.massbaab.com |
www.baabte.com
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