Stacks and NOS (Compressed)

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Stacks and NOS(Compressed)

• Chapter 7 - 9

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Ch 7.1 - Single System IllusionWhat is
transparent?

• Location (WANs look like LANs)
• Naming conventions
• Multiple logons
• Duplicate (replicated) systems
• Time differences
• Failures
• Administration

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Distributed Systems

• Cause transparency
• Distributed Time (NTP)
• Distributed directories (X.500 and LDAP)
• Distributed Security
• Distributed file systems (DCEs DFS)

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Global Directory Services

• Federated directories
• Like telephone (old style) 205-934-8440
• X.500 and LDAP (CCITT standard)
• APIs (Application Programming Interface)
• Vendor specific (Novell and others)
• Standard
• JAVA interfaces
• Distributed objects (CORBA, COM)
• Metadirectories (scripts for existing
  directories)

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X.500 vs. LDAP

• X.500 huge
• LDAP (X.500 lite) small and compact (20 gives
  80 rule)
• LDAP Clients - Netscape, Internet Explorer, Lotus
  Notes
• Moved to IETF standard

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Distributed SecurityC2

• Authentication (Keberos / Digital Certificates)
• Authorization (access control list)
• Audit trails

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Distributed SecurityBetter than C2

• Data Integrity
• Add Encryption and checksums
• Non-Repudiation (Prove in court)
• Evidence of message creation
• Evidence of message receipt
• Time stamp
• See fig 7-7

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Distributed SecuritySingle Signon

• Benefits
• ONE PASSWORD!!!!
• ONE ADMINISTRATOR!!
• Several options
• LDAP
• Enterprise management system
• Upcoming standards (Fig 7-8)

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Ch 7.2 - Internet Security

• Keys
• Private (DES)
• Public (RSA) no trusted 3rd party (fig 7-10,11)
• Digital Certificate
• Certificate Authority (CA)
• X.509, Verisign
• Future of single logon
• pg 153

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Electronic Payments

• SET (VISA and MC)
• Fig 7-14

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Ch 8 RPC and MOMs

• Stacks - fig 8-1
• 8.1 Peer to Peer
• 8.2 Remote Procedure Calls
• 8.3 Message Oriented Middleware (MOM)
• 8.4 MOM vs RPC

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8.1 Peer to Peer

• Sockets (Winsock API)
• TLI (transport layer interface)
• Netware - IPX/SPX
• NetBios and NetBEUI
• Windows Network - Control Panel

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8.2 Remote Procedure Calls (RPC)

• Hide the network details for user and programmer
• Problems for NOS
• What is client fails?
• Data conversion
• Security
• Multiple clients run same function

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8.3 MOM

• Middleware
• Uses queues
• Good when clients and/or servers not available

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8.4 RPC vs MOM

• Figure 8.9
• Mom like postal mail
• RPC like phone call
• Pros and cons (table 8-1)
• ORBs are replacing RPC and MOMs
• allow RPC request and replay
• allow asynchronous messages
• allow publish and subscribe

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Ch 9 - NOS Players

• 9.1 Trends
• 9.2 Players
• 9.3 Evolution
• 9.4 DCE
• 9.5 Internet as a NOS

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9.1 NOS Trends

• NOS gt OS
• MS Lan Manager gt NT 5
• Netware 3.x gt Netware 5.0
• Global directories built in
• Multiplatform (JAVA VM on top of OS)
• Moving beyond LANs (Internet, Intranets)

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9.2 The Players

• Unix NOS
• PC/LAN NOS
• Internet NOS (Most happening here)
• Netscape and AOL
• JAVASoft
• Verisign
• Figures 9.1 and 9.2

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9.4 DCE - The Enterprise NOS

• DCE - Distributed computing environment
• Open Software Forum
• Runs on all platforms
• Vendors buy their code and use

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DCE - Parts

• RPC packages
• Security
• Directory services
• Time services
• MS has used DCE for part of its security and RPC
  in NT 5.0

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9.5 The Internet as an NOS

• Least common denominator of all NOS
• Provides
• global directories (LDAP)
• System management
• Security

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Requirements for E-commerce

• Encryption
• Authentication
• Firewalls
• Non-repudiation

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S-HTTP

• Variant of HTTP
• Uses RSA encryption
• Secures individual documents
• OSI Layer 5-6
• Encryption and authentication

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Transport Layer Security - TLS

• Was SSL
• https//.
• Uses Public Key by RSA
• Developed by Netscape
• Offers X.509
• Secures the communication session
• OSI Layer 4-5
• Encryption and authentication

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IPSec

• Part of IETF IPv6
• Secures channel
• OSI Layer 3-4
• Can work with S-HTTP and TSL (fig 9-9)
• Encryption and authentication

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Firewalls

• Packet filtering
• Watches all packets
• easy to hack
• Proxies
• Operates at higher OSI levels
• Hides IP addresses of internal machines

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VPNs

• Turn Intranet into Extranet using Internet
• Create secure channel
• IPSec is used
• Fig 9-12

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LunchTime!!!!!!!
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Database Servers

• Chapter 10 - 11

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Ch 10 SQL Database Servers

• 10.1 Fundamentals
• 10.2 Function
• 10.3 Stored Procedures

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10.1 SQL Fundamentals

• SQL - Was Structured Query Language
• Performs complex DB operations with few commands
• Often used as a programming language in other
  languages (VB, C, JAVA, )

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What it does

• Allows users to create ad hoc queries of data
• Programming language for databases
• Data definition and administration
• Provides safety features to maintain data
  integrity

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SQL Standards

• Set by ANSI
• SQL-89 - Loosely followed
• SQL-92 - Many vendors followed this standard
• SQL-99 or SQL3 - Being implemented by many(most)
  vendors

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10.2 Database Server Function

• Server often called the engine
• Controls execution
• Provides security
• Provides admin functions
• TLA
• DBA
• DBMS

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Architectures

• Process per Client (fig 10-2)
• provides more security but uses more resources
• ORACLE 6, DB2, Informix
• Multithreaded (fig 10-3)
• More portable, but one bad app can crash
• MS SQL SERVER, SYBASE
• Hybrids
• ORACLE 7, 8

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Which database do you need?

• How many transactions?
• 1k per day
• 100 k per day
• 2 Billion per day
• How much money do you have?
• MS Access / SQL Server cheap (1000)
• Oracle - Not cheap (20,000 up)

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10.3 Stored Procedures

• Pre-built SQL statements loaded on server
• Like RPCs
• Save network traffic
• Fast, but not very flexible

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Ch 11 - SQL Middleware

• 11.1 Options
• 11.2 SQL APIs
• 11.3 Open SQL Gateways

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11.1 Middleware Options

• Single vendor - MS, Oracle, etc (fig 11-1)
• Multivendor -
• Examples???
• Middleware
• Common APIs
• Gateways
• Federated (standardized standards)

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11.2 APIs

• Lots of options -
• SQL-92
• Java SQL
• Xopen
• ODBC gt OLE DB gt ADO
• JDBC

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11.3 Gateways

• Like translators
• Allow communication between multiple vendors and
  platforms

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The End