hooman nili

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Website Hosting
hooman nili
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Background
One of the most significant (and potentially
complicated) parts of implementing and running a
website is enabling users to access your site (or
parts of it) through the Internet. NB. In this
course, we are not interested in websites that
are designed only for internal use or local
access. Well be talking about global websites.
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Our focus
Global website In this course, we are not
interested in websites that are designed only for
internal use or local access i.e. we wont be
discussing intranet-bases websites. Provider-base
d websites Additionally, we assume that our
website is hosted by a provider rather than being
managed in-house.
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Our focus
Web designers versions Well be concentrating,
mainly, on those aspects of web hosting that a
web designer needs to know for decision making
purposes. Web hosting involves a vast areas
internet and computer techs and therefore topics
like datacentre architecture and global routing
(Border Gateway Protocol, etc) are beyond the
scope of this course.
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What is web hosting?
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What is web hosting?
Web hosting is a collection/range of services
available for running a website globally.
Generally, web hosting includes - Domain
registration DNS provision - Web space - FTP
access - Bandwidth provision - Mail facility
(send and receive) - Database - Customer support
(?! What?!!)
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Why not to use an office PC
Although technically is possible to use a home pc
or even a laptop to host a website, most
commercial websites are hosted by specialised
providers. NB. There is nothing wrong with
in-house hosting, but for commercial and
practical reasons, it often makes more sense to
go with a hosting provide. Reasons for this
decision include
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Using a web hosting provider s
- Lower (or zero) infrastructure costs e.g.
power, connectivity, software, - Lower costs of
human/technical resources - Lower load impact on
the enterprises IP network. - Lower risk of
exposing internal network to the Internet
(arguable) - Higher return per investment
(relative arguable)
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Using a web hosting provider -s
- Flexibility - Dependency on third party -
Control -?
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Some Terminology
Web host Also known as provider, hoster, web
hoster, host, or sometimes ISP (also the
in-e-ne- guys) Web space (quantitative
qualitative) AKA disk space or simply space, web
space is the amount disk space available for
web(?) content. It is usually measured in MB.
The host dictates what the total amount is. More
later
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Some Terminology
Bandwidth allowance (quanti. quali.) Sometimes
referred to as data transfer allowance (not
strictly correct, but harmless), bandwidth
allowance is the maximum amount of data that can
be pushed by a server or website. Unit? The
host dictates whether bandwidth allowance is for
upstream, downstream traffic or collectively for
both. More later
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Some Terminology
Shared hosting / virtual hosting Hosting more
than one website (often over 100) on the same
server node. In shared hosting, normally ALL the
resources including CPU, RAM, disk space, and
bandwidth are shared among the hosted sites. We
have seen how a single server can be used to host
multiple sites thanks to virtual hosts (http).
Shared hosting is arguably the commonest type of
hosting. Why?
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Some Terminology
Dedicated hosting A single (usually) server node
is allocated to a single (not martial status)
customer. Unlike shared hosting, the customer
dictates how many sites are hosted on the server
as well as what application can be installed
(some restrictions may apply. Examples?)
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Some Terminology
Dedicated hosting Dedicated servers are often
offered as managed, unmanaged, or semi-managed.
The provider owns(?) the server and is usually
responsible for all the hardware
maintenance/replacement as well as some of the
software depending on the level of management
agreed.
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Some Terminology
Colocation The host provides datacentre physical
space, power, connectivity to IP space and
backbone sources (depending on agreement). The
customer owns the hardware and responsible for
all/part of maintenance as well as network design
and setup.
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Some Terminology
FTP access A basic service for uploading/downloadi
ng files to the web server. The host dictates the
number of ftp users as well as the type of data
that can be stored on the server. Some hosts
impose restrictions on the usage of FTP
(anonymous access) as well as bandwidth allowance
(if not included total bandwidth).
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Some Terminology
Email Typically (not always) web hosts provide
POP, SMTP, IMAP as well as webmail
access. Restrictions include but not limited to
number of mailboxes as well as space. Bandwidth
is not usually an issue since email is not
usually suitable for transferring large data.
Marketing opportunity?
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Some Terminology
Database provision Dynamic/e-commerce websites
often require database provision. Scripting
languages like ASP, and PHP can use databases to
store, retrieve and modify data. MS SQL and
MySQL are among the most popular databases
available.
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Some Terminology
Database provision Almost all hosts offer some
type of database storage. Database provision
involves important technical and commercial
considerations among which are security,
performance, and maintenance. Database driven
website are therefore inherently more expensive
to run.
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Hosting network Example 1 Multi-node servers
FTP Server
SQL Server
Mail Server
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Hosting network Example 2 Single-node servers
FTP Server
SQL Server
Mail Server
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Question
Multi-node or single-node? Discuss!
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Datacentres
Lets now have a look at some real pictures.
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Server node types
The most popular types of server nodes - Tower
Servers - Rack-mount Servers Comparison?
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Bandwidth space - Again
Hosting capacity Bandwidth and space are among
the easily-measurable (not necessarily
predictable) services of web hosting. Bandwidth
and space are sometimes collectively referred to
as the capacity of a website. It is often
important to estimate the initial capacity of a
website in order to choose a hosting plan and
predict the costs.
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Bandwidth space - Again
Hosting capacity is by no means the only decision
making factor nor is it the only cost involved in
providing web hosting. From the admins point of
view bandwidth and space are among the most
important services to monitor, but some providers
dont necessarily share this view with their
customers. More later
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Bandwidth
Bandwidth is defined as the amount of data that
CAN flow through a server in a given period of
time. In other words, bandwidth is the maximum
data transfer capacity available to a server over
a given time period. For example, a sever might
be limited to push 300GB of data in a month.
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Bandwidth IS
Bandwidth is a very important factor for both the
admin and the web designer as it could have a
direct impact on the servers performance (and
hence the website). As the number of hits to a
website increases over time, monitoring bandwidth
usage becomes more and more important as we may
need to re-estimate the hosting capacity needed
and plan accordingly.
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Bandwidth is NOT
Infinite? Regardless of the network connectivity,
bandwidth is at least limited to the physical
properties of the medium used. A responsible
provider should always try to impose a limit on
bandwidth usage, but
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Bandwidth is NOT
not infinite Regardless of the network
connectivity, bandwidth is at least limited to
the physical properties of the medium used. A
responsible provider should always try to impose
a limit on bandwidth usage, but
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Bandwidth is NOT
Free Although LAN-based connectivity doesnt
(usually) require external bandwidth provision,
for WAN-based connectivity (Internet) we almost
always need to buy bandwidth from a backbone
provider (tier- 1 or tier-2? ) and often more
than one backbone connection is required for
increased reliability and redundancy. High
quality bandwidth is expensive.
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Side-note Throughput
Throughput (or data transfer) While bandwidth is
the maximum available data that can flow through
a server theoretically throughput or data
transfer is the actual amount of bandwidth used
over a given time period. Throughput is often
much less than the actual bandwidth allowance.
Why?
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Web space - Again
Web space is (typically) defined as the total
amount of data stored on the hosts server(s).
This includes all the data occupied by emails,
web pages, databases as well as log files and
other temporary data. Web space is usually
measured in MB and GB, but some providers use TB!
(why?)
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Web space - Again
Web space is also a qualitative aspect of web
hosting and could be expensive. It is therefore
important to optimise websites for maximum
efficiency as well as speed. Web space has also
a direct impact on the amount of data transfer
(or traffic) generated by a website. Web
designers often monitor and control web space on
regular basis as part of their website
housekeeping.
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Quality A distinguishing factor
- Bandwidth is not bandwidth - Web space is
not web space What?!!! Why?!!! Example Brunel
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Estimating monthly data transfer
1. Let M be the average size of a web page in
megabytes (assuming 1M is 1000KB). and N the
number of web pages. 2. Estimate the minimum
number of visitors per day, assuming that a
visitor will view all pages, and call it V. 3.
Assume that there are 31 days in a month
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Estimating monthly data transfer
The minimum month traffic, T (in MB), then can be
calculated as follows T 31(MNV) Tip. Its
often a good idea to overestimate V. for
administrative purposes and underestimate it for
marketing purposes. Why? Errors?
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Estimating monthly data transfer Example

• A web site contains 10 web pages, each 70 K in
  average. We expect 100 visitors per day. Whats
  the minimum monthly traffic of the site in
  Megabyte?T 0.07 X 10 X 31 X 100 2170 MB
  2GB/month

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Example 2 The Coffee Town
The Coffee Town UKs No 1 Coffee
Shop www.thecoffeetown.com Bring your friends
Drink up to 700 Litres of coffee for only 10p!
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Example 2 The Dream Highway
The Drivers Dream Town Drivers Favourite
Town www.thedreeeemhighway.com Drive your cars
at up to 400mph, 50 cars per family, up to 100m
long vehicles. Migrate to DDT NOW!
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Thinking Time
Platform Linux vs Window To Microsoft or not
to Microsoft. Thats the question
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Thinking Time
Who is Microsoft
Bill Gates
Steve Ballmer
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Questions

• Which part of your hosting capacity is more
  expensive? space or monthly traffic?
• Why cant the hosting capacity be predicted
  accurately?
• What is the difference between bandwidth and data
  transfer?

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Questions

• Whats overselling
• Unlimited? Does it exist?
• Dedicated-server capacity on shared hosting? Is
  it practical?
• What server resources other than bandwidth and
  space, can a website consume?

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Hosting Offers - Examples

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Hosting Offers - Examples

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Hosting Offers - Examples

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Hosting Offer - Example

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Terms Conditions - Example
Multimedia Files Multimedia files are defined as
any graphics, audio, and video files. Our Web
Hosting accounts are not to be used for the
purposes of distributing and storing unusual
amount of multimedia files. Any Web site whose
disk space usage for storing the multimedia files
exceed 70 of its total usage, either in terms of
total size or number of files, will be deemed to
be using unusual amount of multimedia files.
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Terms Conditions Example 2
 100 Uptime Guarantee We guarantee that
your website will be up all through the year!
However, if your website uptime should be lower
than 89.9, we will give you a full refund of
your hosting charges for that particular effected
month. Please see your Acceptable Use Policy
(AUP) for additional details.