Transcript Class 4 - Turning Wheel

WEB SERVER REQUIREMENTS
Colorado Technical University
IT420
Tim Peterson
3-1
Web Server Platforms
• Hosting Solutions
– Hosted Web site - is a site that your ISP provides the
physical hardware.
– Co-Located Web servers - the hardware is owned by the
web designer and located at the ISP’s facility.
– In-House Web Server - the ISP points the requests to a
server that resides at the developers location.
• The ISP supports the DNS entries.
3-2
Web Server Architecture
• Scalability utilizing a three-tier approach provides
the best use of resources.
• The three tiers are:
– The data-tier is handled by program code embedded as
part of the database server (stored procedures).
– The middle-tier is handled by an application server
handling the business logic of the overall application
(scripts).
– The client-tier is handling the serving of the web pages
(user interface).
3-3
Web Server Architecture contd.
• The database server needs to be the fastest
machine of the architecture.
• Database querying can cause any
bottlenecks that could occur in a Web
architecture.
• Scalability is a must when designing the
Web architecture - to allow the system to
grow as the demands increase.
3-4
CPU Cache
• Cache is high speed memory linked closely
to the CPU.
• Internal Cache (L1) - usually very small and
is based on the CPU chip.
• External Cache (L2) - typically 12-15ns
chips that are located on the motherboard.
• Pipeline Burst Cache (L2) - this type of
cache can provide tremendous speed
3-5
enhancements.
RAM
• Memory that is used for the applications running
on the server.
• The server software uses what memory is
available after the operating system.
• 128MB is typical for good server performance on
an NT platform. Heavy used systems can go up to
1 GIG to keep queries in cache.
• Database servers need as much memory as
possible.
3-6
Hard Disks - Raid Technologies
• Fault Tolerance is needed on reliable Web
servers.
• To provide the proper fault tolerance RAID
arrays are the best approach.
• Raid 0 - Striping
• Raid 1 - Mirroring
3-7
Hard Disks - Raid Technologies - Cont’d
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•
•
•
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RAID 0+1 - Stripe then mirror
Raid 1+0 - Mirror then stripe
Raid 3 - Stripe with parity disks
Raid 5 - Striped with interleaved parity
Other raid technologies are either prototype
or proprietary.
3-8
CD-ROMs/Backups
• CD Drives are needed to provide loading of
software components on the Web server.
• A burnable CD drive could be used to provide
backup services to the server.
• Typical backup methods are using streaming tapes
that can hold large quantities of data.
• Removable disks drives are also a possible
mechanism for backup schemes.
3-9
Power
• Uninterruptible Power Supplies provide a solid
filtered source of electricity.
– Provide power conditioning and filtering as well as a
source of 120VAC if power is lost for short periods of
time.
• Power filters provide protection from power
spikes (lightning).
• Power conditioners compensate for dips and small
spikes in line voltage.
3-10
Communication Architecture
• Point-to-point internet connections are high
performance and large bandwidth connections
(T1, T2, or T3) connected directly through fibre or
microwave.
• Frame Relay is an indirect connection through the
local telephone company (56K, 128K, 384K).
• Digital Subscriber Line (DSL) provides T1
capabilities at low cost.
• Cable modems provides speeds of 512 Kbps - 52
Mbps.
3-11
Communication Architecture
contd.
• Integrated Services Digital Network (ISDN)
provides a wide range of communication
and provides a high-bandwidth, but requires
an ISDN router (32K, 56K, 64K, 128K).
• Dedicated SLIP/PPP provides a lowbandwidth connection, and is available
24X7 - does require a modem online at all
times (56K). Good for testing.
3-12
Communication Hardware
• Routers are a device that acts as a traffic director
for the Ethernet traffic.
• Directs data packets to the requested IP address.
• CSU/DSU is a modem device connected to leased
phone lines providing translating protocols.
• Hubs are devices that allow multiple pieces of
hardware to be connected together.
3-13
Communication Connections
• TCP/IP is typically used over an Ethernet
architecture.
• Coax cable can be used to provide 1MBit/S
highways for Ethernet traffic.
• 10Base-T twisted pair cables can be used to
provide 10MBit/S highways for Ethernet traffic.
• Fiber cable or an RJ-45 connection can be used to
provide 100MBit/S highways for Ethernet traffic.
3-14
Server Software
• Windows NT Server provides a solid
platform as an operating system supporting
Web Servers.
– Microsoft IIS, Bea Weblogic, Bluestone, Cold
Fusion, Silver Stream
• An operating system that provides virtual
memory is a must for good Web Server
performance.
3-15
Web Server Selection Criteria
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•
•
•
•
•
•
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Performance
Cost
Support
Ease of content management
Application development features
Ease of integration with NT
Support for SSL
Integration with back end databases.
3-16
Internet Programming
• Windows Sockets (WINSOCK) - provides
communications between machines - local or
Internet related.
• Winsock replaces the need for the following
technologies:
–
–
–
–
Direct serial port connections
Dynamic Data Exchange (DDE)
Network DDE
Mailslots
3-17
Winsock Programming
• Creates an abstraction layer associated to
the hardware.
• There have been no real standards
associated to DDE programming, which has
caused a frustration when utilizing DDE to
accomplish a data transaction.
• DDE was just a stepping stone to the Object
Linking and Embedding (OLE)
technologies.
3-18
OSI Model
•
•
•
•
Application Layer - Network Applications
Presentation Layer - Data presentation STD
Session Layer - Manage sessions for Apps
Transport Layer - End-to-End error
handling
• Network Layer - Manage Connections
• Data Link Layer - Provide data delivery
• Physical Layer - Network Physical char.
3-19
TCP/IP
• TCP - Transmission Control Protocol resides at the transport layer.
• IP - Internet Protocol - resides at the
network layer.
• TCP/IP covers an entire suite of protocols
used with the Internet.
• IP is used for the identification of the
connection being made with another
3-20
computer.
Ports
• Communications for information between
computers relies on the IP for the address to the
other computer and a port address associated to
the type of data being transmitted.
• HTTP (WWW) - 80, FTP - 20 and 21
• Gopher - 70,
SMTP (e-mail) - 25
• POP3 (e-mail) - 110, Telnet - 23
• Whois - 43,
Finger - 79
3-21
Sockets
• A socket is the combination of an IP address
and a port.
• A socket can also refer to Berkeley Sockets,
which are a set of functions for Unix
programmers for Internet access.
• Another definition of sockets is Windows
Sockets. It provides Windows specific
routines to aid in writing Windows
applications.
3-22
Winsock Sockets
• There are only 44 functions in Winsock 1.1
- fairly straight forward implementation in
C/C++.
• There are a few commercial ActiveX
controls available to ease development in
VB.
• Shareware - DSSOCK from Dolphin
Systems in Toronto, Canada.
3-23
Winsock API
• Windows is shipped with the Winsock API,
but it is hard to work with and can be
cumbersome to program with.
• There are no speed or development
advantages associated with using the
Winsock API over the DSSOCK ActiveX
object.
3-24
DSSOCK
• The filename for the ActiveX object is
DSSOCK32.OCX.
• The object must be registered with VB to be able
to use it.
• Select the components window and select Browse.
• Select the object from the directory that it was
placed in and it will become available to you in
the components dialog.
3-25