Krerk Piromsopa.

Advance Net-Centric Computing Technology

Krerk Piromsopa.

Department of Computer Engineering.

Chulalongkorn University.

Krerk Piromsopa.

Issue

• Load-Balancing / Fault-Tolerant

• Web Caching

• Content Delivery

• Grid

• Performance– SpecWeb99

– TPC

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Load Balancing Web Server

• The DNS Approach

• The Reverse Proxy Approach

• Server Processes

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Reverse Proxy Approach

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Cache

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Proxy Network

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Content Delivery

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Akamai (flash crowns performance)

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Akamai (consistent site)

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Content Delivery Network

A CDN is a service offered by a service provider, either an established one (such as AT&T) or a CDN-only provider. Fundamentally, a CDN maintains multiple locations with copies of the same content, and uses information about the user and the content requested to “route” the user to the most appropriate site. The customers of a CDN will be companies that wish to offer their content to a geographically distributed, potentially large, audience.

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CDN:Architecture

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CDN

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CDN: Content Routing

• Redirection– Global Redirection – DNS

– Local Redirection – Layer/4-7 Switching

– Local Redirection – WCCP

• Metrics for Redirection– Network proximity

– Geographical proximity

– Response time

– User type

– Server load

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Grid

• Grid is a type of parallel and distributed system that enables the sharing, selection, and aggregation of resources distributed across "multiple" administrative domains based on their (resources) availability, capability, performance, cost, and users' quality-of-service requirements.

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SpecWeb99

• SPECweb99 represents a standardized benchmark for measuring web server performance. Building upon the success of SPECweb96, SPECweb99 provides users an objective measure allowing users to make fair comparisons between results from a wide range of systems.

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SpecWeb99 Flow DiagramStatic GET 70%

Standard Dynamic GET 12.45%

Standard Dynamic GET (CGI) 0.15%

Customized Dynamic GET 12.6%

Dynamic POST 4.8%

Total 100%

See result at :

http://www.specbench.org/osg/web99/results/web99.html

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TPC

• TPC Benchmark? W (TPC-W) is a transactional web benchmark. The workload is performed in a controlled internet commerce environment that simulates the activities of a business oriented transactional web server. The workload exercises a breadth of system components associated with such environments, which are characterized by:

– Multiple on-line browser sessions

– Dynamic page generation with database access and update

– Consistent web objects

– The simultaneous execution of multiple transaction types that span a breadth of complexity

– On-line transaction execution modes

– Databases consisting of many tables with a wide variety of sizes, Attributes, and relationships

– Transaction integrity (ACID properties)

– Contention on data access and update

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Reference

• Ralf S. Engelschall, “Load Balancing Your Web Site ,” http://www.webtechniques.com/archives/1998/05/engelschall/

• “Why Performance Matters,” http://www.akamai.com/

• Matthew Liste, Thrupoint, “Content Delivery Networks (CDNs) – A Reference Guide,”http://www.ciscoworldmagazine.com/

• “Grid Computing Info Centre (GRID Infoware),” http://www.gridcomputing.com/

• “SpecWeb99,” http://www.spec.org/osg/web99/

• “TPC-W,” Transaction Processing Performance Council, http://www.tpc.org/tpcw/default.asp