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WEB SERVER REQUIREMENTS

Colorado Technical University

IT420

Tim Peterson

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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.

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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).

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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.

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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 enhancements.

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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.

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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

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Hard Disks - Raid Technologies - Cont’d

• 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.

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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.

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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.

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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.

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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 low-bandwidth connection, and is available 24X7 - does require a modem online at all times (56K). Good for testing.

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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.

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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.

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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.

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Web Server Selection Criteria

• Performance• Cost• Support• Ease of content management• Application development features• Ease of integration with NT• Support for SSL• Integration with back end databases.

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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

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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.

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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.

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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 computer.

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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

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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.

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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.

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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.

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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.