04-09-2014, 11:10 AM
Web operating system
[attachment=67620]
ABSTRACT
we argue for the power of providing a commonset of OS services to wide area applications, includingmechanisms for resource discovery, a global namespace, remoteprocess execution, resource management, authentication,
security. On a single machine, application developerscan rely on the local operating system to provide these abstractions.In the wide area, however, application developers areforced to build these abstractions themselves or to do without.This ad-hoc approach wastes programmer effort and systemresources. To address these problems, WebOS provides basicoperating systems services needed to build applications thatre geographically distributed, highly available, incrementallyscalable, and dynamically reconfiguring. Experience with anumber of applications developed underWebOS indicates thatit simplifies system development and improves resource utilization.In particular, we use WebOS to implement Rent-AServer
to provide dynamic replication of overloaded services
across the wide area in response to client demands
Introduction
The growth rate and scale of theWeb presents a familyof difficult challenges for the Web as a system.While the underlying communications infrastructurehas proved surprisingly robust, we believe that thepresence of a higher level system design will enable
advances in the capabilities of Web applications. In
short,we believe the development of an operating system
for theWeb will provideWeb applications convenient
access to shared resources. The operating system
will efficiently manage these resources for the
benefit of all users of the system.
Today, the operating environment of the Web
could be characterized as location-unaware browsers
This work was supported in part by the Defense Advanced Research
Projects Agency (N00600-93-C-2481, F30602-95-C-0014), the National
Science Foundation (CDA0401156), CaliforniaMICRO, theAT&T Foundation,
Digital Equipment Corporation, Exabyte, Hewlett Packard, Intel, IBM,
Microsoft, Mitsubishi, Siemens Corporation, SunMicrosystems, and Xerox.
Anderson was also supported by a National Science Foundation Presidential
Faculty Fellowship. Yoshikawa is supported by a National Science Foundation
Fellowship. The authors can be contacted at fvahdat, dahlin,
eastham, chad, tea, cullerg[at]cs.berkeley.edu.
making mostly read-only requests to hardwareconstrained
servers over an almost oblivious network
fabric. Our goal is to demonstrate a different vision
of the Web operating environment where computation
and storage servers in the Web function
cooperatively to provide efficient access to resources
supporting Web applications. These core servers
are incrementally scalable and highly available,
browsers are aware of the service characteristics
and the state of the network connection to these
servers, and servers can cooperate to share load and
distribute data throughout the Web to both reduce
latency and save bandwidth. This vision requires a
software framework for development of advanced
Web applications.
To demonstrate that our vision of the Web is
achievable, we are constructingWebOS, a framework
for building highly available, incrementally scalable,
self-tuning, dynamically reconfiguring and geographically
aware Web services. WebOS must provide traditional
local OS functionality at the global level, including:
naming, resource allocation, inter-process
communication, scheduling, fault tolerance, and authentication.
To this end, we have initial prototypes
of: (i) Smart Clients for fault tolerant, load balanced
access to Web services, (ii) WebFS, a global cache
coherent filesystem, (iii) a virtual machine supporting
secure program execution and mechanisms for resource
allocation, and (iv) authentication for secure
access to global Web resources. To evaluate WebOS,
we are developing a global cooperative cache ofWeb
pages, allowing replication and migration ofWeb services
during times of peak demand.
The rest of this paper will describe the WebOS design,
implementation status, and supported applications.
Section 2 describes our requirements for highperformance
scalable Web services. Section 3 and 4
presents the WebOS design and implementation status.
Section 5 details an application we are building
to evaluate WebOS. Section 6 describes related work
Smart Clients
In WebOS, we address the shortcomings of existing
solutions for scalable service access through the
Smart Client architecture [56]. Smart Clients allow
service-specific extensions to be dynamically loaded
into the client to provide tracking of the mobile service,
load balancing among individual servers, and
fault transparency to end users. The portability of
Java and its availability in all major Internet browsers
allow us to distribute these extensions as Java applets.
A service-specific applet is retrieved by the user’s
browser each time a service is accessed. The applet
contains hints for the locations of service providers.
A typical applet’s code is composed of two cooperating
threads: a customizable graphical interface
thread providing the user’s view of the service and a
director thread responsible for performing load balancing
among service representatives and maintaining
the necessary state to mask transparency in the
case of failure. Both the interface and director are extensible
in a service-specific manner. A prototype of
Smart Clients is currently operational and has been
used to implement scalable access to Internet services,
including FTP, telnet, and Internet chat.
Request
Response/
State update
GUI
Thread
Director
Thread
User
Requests
Client-Side Applet
Nearby
Mirror
Distant
Mirror
Conclusions
The explosion in the use of the Internet has created
a need for scalable, fault tolerant, and geographically
distributed web services. Unfortunately, the technical
understanding of how to build web services that can
support very large numbers of clients has lagged far
behind the demand. Our hypotheses are that services
need to be able to migrate dynamically between geographically
distributed sites to handle bursty requests
and to avoid network congestion, and that clients have
a role in providing transparent access to dynamically
migrating services. The goal of WebOS is to provide
a software framework for highly available, dynamically
adaptable, and incrementally scalable web services
running on a set of geographically distributed
machines.
A number of key components comprise theWebOS
architecture. Smart Clients allow portions of service
functionality to be migrated onto the client machines.
Smart Clients cooperate with servers to provide load
balanced fault tolerant access to Web services. To
aid in construction of scalable services, WebOS also
includes a global cache coherent file system, an authentication
model to ensure secure access to private
state and executables, a virtual machine for safe execution
of service binaries, and resource allocation
tools to allow for adjudication among competingWeb
services. Most of the key WebOS components have
been prototyped. To demonstrate the viability of our
ideas and the prototype, we are building a Web cooperative
cache of web pages, allowing surrogates located
at strategic points in the Internet to serve cachecoherent
content on behalf of heavily loaded or distantWeb
services. We believe that theWebOS infrastructure
will also allow rapid prototyping of a number
of other compelling scalable Internet services, including:
a low-latency chat service, a distributed compute
server, and multicast-based news broadcast applications
[attachment=67620]
ABSTRACT
we argue for the power of providing a commonset of OS services to wide area applications, includingmechanisms for resource discovery, a global namespace, remoteprocess execution, resource management, authentication,
security. On a single machine, application developerscan rely on the local operating system to provide these abstractions.In the wide area, however, application developers areforced to build these abstractions themselves or to do without.This ad-hoc approach wastes programmer effort and systemresources. To address these problems, WebOS provides basicoperating systems services needed to build applications thatre geographically distributed, highly available, incrementallyscalable, and dynamically reconfiguring. Experience with anumber of applications developed underWebOS indicates thatit simplifies system development and improves resource utilization.In particular, we use WebOS to implement Rent-AServer
to provide dynamic replication of overloaded services
across the wide area in response to client demands
Introduction
The growth rate and scale of theWeb presents a familyof difficult challenges for the Web as a system.While the underlying communications infrastructurehas proved surprisingly robust, we believe that thepresence of a higher level system design will enable
advances in the capabilities of Web applications. In
short,we believe the development of an operating system
for theWeb will provideWeb applications convenient
access to shared resources. The operating system
will efficiently manage these resources for the
benefit of all users of the system.
Today, the operating environment of the Web
could be characterized as location-unaware browsers
This work was supported in part by the Defense Advanced Research
Projects Agency (N00600-93-C-2481, F30602-95-C-0014), the National
Science Foundation (CDA0401156), CaliforniaMICRO, theAT&T Foundation,
Digital Equipment Corporation, Exabyte, Hewlett Packard, Intel, IBM,
Microsoft, Mitsubishi, Siemens Corporation, SunMicrosystems, and Xerox.
Anderson was also supported by a National Science Foundation Presidential
Faculty Fellowship. Yoshikawa is supported by a National Science Foundation
Fellowship. The authors can be contacted at fvahdat, dahlin,
eastham, chad, tea, cullerg[at]cs.berkeley.edu.
making mostly read-only requests to hardwareconstrained
servers over an almost oblivious network
fabric. Our goal is to demonstrate a different vision
of the Web operating environment where computation
and storage servers in the Web function
cooperatively to provide efficient access to resources
supporting Web applications. These core servers
are incrementally scalable and highly available,
browsers are aware of the service characteristics
and the state of the network connection to these
servers, and servers can cooperate to share load and
distribute data throughout the Web to both reduce
latency and save bandwidth. This vision requires a
software framework for development of advanced
Web applications.
To demonstrate that our vision of the Web is
achievable, we are constructingWebOS, a framework
for building highly available, incrementally scalable,
self-tuning, dynamically reconfiguring and geographically
aware Web services. WebOS must provide traditional
local OS functionality at the global level, including:
naming, resource allocation, inter-process
communication, scheduling, fault tolerance, and authentication.
To this end, we have initial prototypes
of: (i) Smart Clients for fault tolerant, load balanced
access to Web services, (ii) WebFS, a global cache
coherent filesystem, (iii) a virtual machine supporting
secure program execution and mechanisms for resource
allocation, and (iv) authentication for secure
access to global Web resources. To evaluate WebOS,
we are developing a global cooperative cache ofWeb
pages, allowing replication and migration ofWeb services
during times of peak demand.
The rest of this paper will describe the WebOS design,
implementation status, and supported applications.
Section 2 describes our requirements for highperformance
scalable Web services. Section 3 and 4
presents the WebOS design and implementation status.
Section 5 details an application we are building
to evaluate WebOS. Section 6 describes related work
Smart Clients
In WebOS, we address the shortcomings of existing
solutions for scalable service access through the
Smart Client architecture [56]. Smart Clients allow
service-specific extensions to be dynamically loaded
into the client to provide tracking of the mobile service,
load balancing among individual servers, and
fault transparency to end users. The portability of
Java and its availability in all major Internet browsers
allow us to distribute these extensions as Java applets.
A service-specific applet is retrieved by the user’s
browser each time a service is accessed. The applet
contains hints for the locations of service providers.
A typical applet’s code is composed of two cooperating
threads: a customizable graphical interface
thread providing the user’s view of the service and a
director thread responsible for performing load balancing
among service representatives and maintaining
the necessary state to mask transparency in the
case of failure. Both the interface and director are extensible
in a service-specific manner. A prototype of
Smart Clients is currently operational and has been
used to implement scalable access to Internet services,
including FTP, telnet, and Internet chat.
Request
Response/
State update
GUI
Thread
Director
Thread
User
Requests
Client-Side Applet
Nearby
Mirror
Distant
Mirror
Conclusions
The explosion in the use of the Internet has created
a need for scalable, fault tolerant, and geographically
distributed web services. Unfortunately, the technical
understanding of how to build web services that can
support very large numbers of clients has lagged far
behind the demand. Our hypotheses are that services
need to be able to migrate dynamically between geographically
distributed sites to handle bursty requests
and to avoid network congestion, and that clients have
a role in providing transparent access to dynamically
migrating services. The goal of WebOS is to provide
a software framework for highly available, dynamically
adaptable, and incrementally scalable web services
running on a set of geographically distributed
machines.
A number of key components comprise theWebOS
architecture. Smart Clients allow portions of service
functionality to be migrated onto the client machines.
Smart Clients cooperate with servers to provide load
balanced fault tolerant access to Web services. To
aid in construction of scalable services, WebOS also
includes a global cache coherent file system, an authentication
model to ensure secure access to private
state and executables, a virtual machine for safe execution
of service binaries, and resource allocation
tools to allow for adjudication among competingWeb
services. Most of the key WebOS components have
been prototyped. To demonstrate the viability of our
ideas and the prototype, we are building a Web cooperative
cache of web pages, allowing surrogates located
at strategic points in the Internet to serve cachecoherent
content on behalf of heavily loaded or distantWeb
services. We believe that theWebOS infrastructure
will also allow rapid prototyping of a number
of other compelling scalable Internet services, including:
a low-latency chat service, a distributed compute
server, and multicast-based news broadcast applications