Improving Web Performance Improving Web Performance
Recommend Documents
servers do not reflect the quality factors of the service ... Agreement)[3] for producing and monitoring service .... when the server performs the best is set as the.
the web servers apply the FIFO and static priority scheduling ... through the web server, our research analyzes various ... agreements and is easy to monitor.
[email protected], [email protected]. Abstract ... Web Services in one logical unit in order to accomplish a complex task ... previous studies [3] it is shown that unexpected bulk ..... from a prior service and sending a request to a next.
NET templates; in order to illustrate the services and features associated with Microsoft Azure Platform. Keywordsâ Cloud Computing, Web Hosting, Microsoft ...
while maintaining individual application performance tar- gets. Performance is .... intensive Open Source Database Benchmark suite (OSDB) perform differently ...
Dec 17, 2006 - of the file, saving the web pages at the client side, changing the burst nature of traffic ... unnecessar
particular, Semantic Web applications, which use triple stores as persis- ... improve the performance of triple stores b
smooth migration from desktop-based to Web-based applications, as well as on ... which is used in Google's Chrome browser, is so called. DNS prefetching.
markup. The consequences of such bloated HTML are unnecessarily increase storage costs, transmission costs, download tim
growth of Internet, web users are suffering from the network congestion and ... used for much reduction in bandwidth con
I. INTRODUCTION. As far as communication for distributed applications in ... dynamic strategy based on client profiling
[email protected]. 4. WWW URL: http://www.usenix.org/. Improving Web Server
Performance by Caching Dynamic Data. Arun Iyengar and Jim Challenger.
0164-1212/$ - see front matter à 2004 Elsevier Inc. All rights reserved. ... reduction in network latency at a cost of 40% increase in network traffic.
between clustered back-end web servers based on the load- ing condition of the ... demonstrate that our proposed algorithm yields the best performance when ...
Improving Software Development Project Team Performance: A Web-based. Expert Support System for Project Control. Donna Dufner, Ojoung Kwon, Aaron ...
particular, Semantic Web applications, which use triple stores as persis- ... improve the performance of triple stores by developing better storage, indexing.
Inc. which measures the number of requests per ..... This behavior is an example of Amdahl's Law 9 . ..... 16 Netscape Communications Corporation. The.
For every page in kernel a graph is constructed from pages .... [2] H.P.ALSSO and F.SMILL, Thinking on the Web, John WILLEY New. Jersey 2006. [3] Ee -Peng ...
Keywords: Query, Optimization, SQL Server. Introduction. There are many
situations in which effi- ciency and performance are the last criteria considered
when ...
Speaker attributed variability are undesirable in speaker independent speech recognition systems. The gender of the speaker is one of the influential sources of ...
pDHpE In focus hsc course. 264. To improve athletic performance it is vital that
training programs are appropriate and specific to the athlete, whether they be ...
Once the focus moves mainly to muscular power, a series of assistance exercises
should be identified. These recruit smaller muscle groups specific to the sport ...
Improving Web Performance Improving Web Performance
Jim Kurose, Keith Ross ... Web caches (proxy server). ❒ user sets browser: Web
... server origin server. 4. More about Web caching. ❒ Cache acts as both client.
Improving Web Performance
These slides are based on the slides made available by the authors of
Computer Networking: A Top Down Approach Featuring the Internet, 2nd edition. Jim Kurose, Keith Ross Addison-Wesley, July 2002.
1
Improving Web Performance ❒ HTTP ❍ Persistent connections (discussed earlier) ❒ Web Caching ❒ Content Delivery Networks
2
1
Web caches (proxy server) Goal: satisfy client request without involving origin server ❒ user sets browser: Web
accesses via cache ❒ browser sends all HTTP requests to cache ❍ ❍
object in cache: cache returns object else cache requests object from origin server, then returns object to client
origin server HT T
clientHTTP
Pr
eq u
Proxy server
est r es pon se st e u req n se TP spo HT e r TP HT
t ues re q P e T o ns HT esp r TP HT
client
origin server 3
More about Web caching ❒ Cache acts as both client
and server ❒ Cache can do up-to-date check using If-modifiedsince HTTP header ❍
❍
Issue: should cache take risk and deliver cached object without checking? Heuristics are used.
❒ Typically cache is installed
Why Web caching? ❒ Reduce response time for
client request.
❒ Reduce traffic on an
institution’s access link. ❒ Internet dense with caches enables “poor” content providers to effectively deliver content
by ISP (university, company, residential ISP)
4
2
Caching example (1) Assumptions ❒ average object size = 100,000 bits ❒ avg. request rate from institution’s browser to origin serves = 15/sec ❒ delay from institutional router to any origin server and back to router = 2 sec Consequences
origin servers public Internet
1.5 Mbps access link institutional network
10 Mbps LAN
utilization on LAN = 15% utilization on access link = 100% ❒ total delay = Internet delay + access delay + LAN delay = 2 sec + minutes + milliseconds ❒ ❒
institutional cache 5
Caching example (2) Possible solution ❒ increase bandwidth of access link to, say, 10 Mbps Consequences utilization on LAN = 15% utilization on access link = 15% ❒ Total delay = Internet delay + access delay + LAN delay = 2 sec + msecs + msecs ❒ often a costly upgrade
origin servers public Internet
❒ ❒
10 Mbps access link institutional network
10 Mbps LAN
institutional cache 6
3
Caching example (3) origin servers
Install cache ❒
suppose hit rate is .4
Consequence ❒ ❒ ❒
❒
=
40% requests will be satisfied almost immediately 60% requests satisfied by origin server utilization of access link reduced to 60%, resulting in negligible delays (say 10 msec) total delay = Internet delay + access delay + LAN delay .6*2 sec + .6*.01 secs + milliseconds < 1.3 secs
public Internet
1.5 Mbps access link institutional network
10 Mbps LAN
institutional cache 7
Content distribution networks (CDNs) ❒ The content providers are
the CDN customers. Content replication ❒ CDN company installs hundreds of CDN servers throughout Internet ❍ in lower-tier ISPs, close to users ❒ CDN replicates its customers’ content in CDN servers. When provider updates content, CDN updates servers
origin server in North America
CDN distribution node
CDN server in S. America CDN server in Europe
CDN server in Asia
8
4
CDN example
HTTP request for www.foo.com/sports/sports.html
Origin server
1 2 3
DNS query for www.cdn.com
CDNs authoritative DNS server HTTP request for www.cdn.com/www.foo.com/sports/ruth.gif
origin server ❒ www.foo.com ❒ distributes HTML
Nearby CDN server
❒ Replaces: http://www.foo.com/sports.ruth.gif
with http://www.cdn.com/www.foo.com/sports/ruth.gif
CDN company ❒ cdn.com ❒ distributes gif files ❒ uses its authoritative DNS server to route redirect requests 9
More about CDNs routing requests ❒ CDN creates a “map”, indicating distances from leaf ISPs and CDN nodes ❒ when query arrives at authoritative DNS server: ❍
❍
not just Web pages ❒ streaming stored audio/video ❒ streaming real-time audio/video ❍
