distributed applications session 5 14:00 - 15:00 dr deepak b phatak, iit bombay
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DISTRIBUTED APPLICATIONS
Session 5 14:00 - 15:00
Dr Deepak B Phatak, IIT Bombay
Dr Phatak, IIT Bombay Distributed Applications 2
SESSION OVERVIEW
Indian Banking Scenario Distributed Paradigms How to Construct the
Distributed Infrastructure
Dr Phatak, IIT Bombay Distributed Applications 3
BANKING BUSINESS
Primarily Based On– Interest Spread
– Fee Based Services Multi Location Operations
– Hierarchical Branch Network
Dr Phatak, IIT Bombay Distributed Applications 4
BANKING BUSINESS
Requires Emphasis on– Fast Movement of Funds
– Purposeful Expansion and Retention of Customer Base
– Non Repudiation of Valid Transactions. (TXNs)
Dr Phatak, IIT Bombay Distributed Applications 5
CONVENTIONAL RETAIL BANKING
Low Value High Volume TXNs Attractive Deposit Products Speedy Customer Service Local TXNs, Within a Branch, Remote TXNs, Within A City, Anywhere Globally
Dr Phatak, IIT Bombay Distributed Applications 6
COMEERCIAL BANKING
Term Loans– Speedy Application Processing
– Avoiding NPAs Fee Based Services
– Fast Turn Around of TXN
– Special Services Needed
Dr Phatak, IIT Bombay Distributed Applications 7
HOUSE KEEPING
Management Reporting– Consolidation Reports
– Control Reports
– Performance Reports
– Statutory Reports
– Audit Reports
Dr Phatak, IIT Bombay Distributed Applications 8
INDIAN BANKING SCENARIO
Traditionally Branch Centric GL is Accounting Backbone S..S..Slow Fund Movement Rudimentary Central Control Focus On Customer Service ???
Dr Phatak, IIT Bombay Distributed Applications 9
INDIAN BANKING SCENARIO
Use Of Modern IT– Started with Back Office
– TBM: Better Local Operations
– Useless Networks
– More Useless MIS, DSS
Dr Phatak, IIT Bombay Distributed Applications 10
INDIAN BANKING SCENARIO
Coexistence of Computerised, Semi-Automated and Manual Branch Operations
Stronger Networks Emerging Any Banking Paradigm Must
– Work in Existing Situation
– Quickly Exploit Changes
Dr Phatak, IIT Bombay Distributed Applications 11
DISTRIBUTED PARADIGM
Emerged Primarily – To Provide Autonomous Operations
at Multiple Sites
– To Exploit Cheaper MIPS on Smaller Machines
All Real Life End to End Computerisation is Distributed
Dr Phatak, IIT Bombay Distributed Applications 12
DISTRIBUTED PARADIGMS
Hierarchies of Servers/Clients Use of Message Queues and/Or
TP Monitors Multiple Delivery Mechanisms
Dr Phatak, IIT Bombay Distributed Applications 13
METHODOLOGIES
Software Engineering Distributed Functionality Design Network Design Configuring an Application for
Growth– Change Management
Dr Phatak, IIT Bombay Distributed Applications 14
DELIVERY MECHANISMS
Post, Telegrams, Fax Machine Readable Data On Media Data Transfer Through Networks
Dr Phatak, IIT Bombay Distributed Applications 15
EARLY NETWORKS
Arcnet and Novell Ethernet and Token ring TCP/IP gets embedded into BSD
Unix
Dr Phatak, IIT Bombay Distributed Applications 16
MODERN NETWORKS
Ethernet
– 10 Mbps, 75% Market, Over 40 Million nodes
Token Ring – 4/16 Mbps, 16%
Fast Ethernet – 100 Mbps, 1%, growing fast
Dr Phatak, IIT Bombay Distributed Applications 17
MODERN NETWORKS
FDDI – 100 Mbps, < 1%, Dying
ATM – 25 Mbps to 2.4 Gbps, Nascent
Dr Phatak, IIT Bombay Distributed Applications 18
MODERN NETWORKS (WAN BACKBONE)
North American– T1 or DS1 : 1.54 Mbps– T3 or DS3 : 44.73 Mbps
European (and Indian)– E1 : 2.04 Mbps (CCITT standard)– E2 : 8.44 Mbps– E3 : 34.36Mbps
Dr Phatak, IIT Bombay Distributed Applications 19
MODERN NETWORKS (WAN BACKBONE)
Sonet fibre Standards (ANSI, Synchronous optical Network)– OC1 to OC3 (51.84, 103.68, 155.52 Mbps)– OC12 (622.08 Mbps)– OC24 and OC48 (1.244 Gbps, 2.488 Gbps)
Dr Phatak, IIT Bombay Distributed Applications 20
MODERN NETWORKS
LAN-WAN-LAN Interconnect Various LAN Protocols
– TCP/IP, IPX/SPX, SNA, NETBEUI
Remote access PC– SLIP, PPP.
Dr Phatak, IIT Bombay Distributed Applications 21
MODERN NETWORKS
LAN to LAN– Bridge, Gateway
– IP Switching. LAN to WAN
– Multi Protocol Routers.
– X.25 Switches, Gateway
Dr Phatak, IIT Bombay Distributed Applications 22
MODERN NETWORKS
WAN Backbone– IP Over Leased Circuits / Dial up
Lines (Internet Is IP)
– X.25, Frame Relay, ATM (IP Can Run Over These)
– VSATS ( Delays, 400 ms Per Hop)
Dr Phatak, IIT Bombay Distributed Applications 23
TRANSACTIONS
ACID Properties Revisited–Atomicity: All or None
–Consistency : Stable & Correct End State
– Isolation : Unaffected by Other Happenings
–Durability : Persistent Effect
Dr Phatak, IIT Bombay Distributed Applications 24
TRANSACTIONS
A Single User Example– Is It Simple to Handle?
– What Happens in a Crash? Simple If Things Work
Correctly Difficult If Things Go Wrong.
Dr Phatak, IIT Bombay Distributed Applications 25
TRANSACTIONS
Concurrent Distributed Transactions, More Problems– Consistency and Isolation
– Roll Back Is Difficult Lock Step Synchronization
Through Two Phase Commit
Dr Phatak, IIT Bombay Distributed Applications 26
TRANSACTIONS
Flat Transactions– Activities Are at Same Level
– SQL Implements Two Phase Commit Protocol
– Backbone of Most (Leaf-level) Applications
Dr Phatak, IIT Bombay Distributed Applications 27
FLAT TRANSACTIONS
Limitations –Complex Sub-activities With Partial
Roll Back?
–Human in the Loop Locks Resources
–Temporally Long Transactions
–Bulk Update Transaction
Dr Phatak, IIT Bombay Distributed Applications 28
PAYMENT SETTLEMENT
A Complex Transaction Jena of Jharsuguda gives a cheque
to Kantheeswaran at Kandivali– Kanthee Banks with Bank A at
Kandiwali: A(K)
– Jena With Bank B(J)
Dr Phatak, IIT Bombay Distributed Applications 29
PAYMENT SETTLEMENT
Kanthee Presents Cheque to A(K) and demands money
A(J) credits Kanthee’s account AFTER collecting from B(J)
Dr Phatak, IIT Bombay Distributed Applications 30
DISTRIBUTED PROCESSING SOLUTION
Local Data Base Local Data Base
Bank B Bank A
NCC
Kantheeswaran
KandiwaliJharsuguda
Jena
DistributedTransaction
Dr Phatak, IIT Bombay Distributed Applications 31
PAYMENT SETTLEMENT
A presents the instrument to NCC NCC records information
– Sorts all Instruments for Bank B
– Asks B to pay A B sends Cheque to Jharsuguda (J)
Dr Phatak, IIT Bombay Distributed Applications 32
PAYMENT SETTLEMENT
B(J) debits Jena Informs NCC and A(K) A(K) credits Kanthee Multiple Service Branches Are
Actually Involved
Dr Phatak, IIT Bombay Distributed Applications 33
PAYMENT SETTLEMENT
Transaction becomes funny if – Jena has no funds
– Cheque is lost in transit
– B Debits Jena But Sits Tight
– A Receives Info, But Does Not Credit Kanthee
Dr Phatak, IIT Bombay Distributed Applications 34
PAYMENT SETTLEMENT
More fun NCC Asks B to Pay A
– Later, B says give back my money Jena debited but Kanthee not
credited (Someone Using Float)– Kanthee sues A for delay
Dr Phatak, IIT Bombay Distributed Applications 35
DISTRIBUTED PROCESSING SOLUTION
Local Data Base Local Data Base
Bank B Bank A
NCC
Kantheeswaran
KandiwaliJharsuguda
Jena
Inter Bank Transaction Switch
DistributedTransaction
BSwitch
ASwitch
Dr Phatak, IIT Bombay Distributed Applications 36
TRANSACTIONS
Emerging Transaction requirements– Distributed Transaction
– Multiple Processing Nodes
– Not All Nodes Computerised
– Not All Links Electronic
Dr Phatak, IIT Bombay Distributed Applications 37
TRANSACTIONS
ACID properties difficult to maintain for a Complex Transaction
Human in the Loop is a MUST– Carry Physical Instruments
– Multiple Data Capture
– Verify Signatures at B(J)
Dr Phatak, IIT Bombay Distributed Applications 38
TRANSACTIONS
A Possible Solution is To Reduce Humans in the Loop– Cheque Is a Message and Not a
Physical Instrument– NCC Is a Swithing System and Not
a Physical Clearing House– Electronic Transfer
Dr Phatak, IIT Bombay Distributed Applications 39
TRANSACTIONS
Multiple Ways of Handling – MICR processing
– Electronic Fund Transfer
– Debit and Credit Clearing
– Completely Automated Switch
Dr Phatak, IIT Bombay Distributed Applications 40
TRANSACTIONS
Emerging Requirements– Multi Location Transactions
– Incorporation of Work Flow
– Internet Transactions
Dr Phatak, IIT Bombay Distributed Applications 41
MIDDLEWARE
A Vague Term All Distributed Software
Components That Support Interactions Between Application Software Executing On Clients and Servers
Dr Phatak, IIT Bombay Distributed Applications 42
MIDDLEWARE
General– Communication stacks
– Distributed Directories
– Authentication Service
– Remote Procedure calls
– Queuing Services
– Message Oriented Middleware (MOM)
Dr Phatak, IIT Bombay Distributed Applications 43
MIDDLEWARE
Service Specific– Database related : ODBC, DRDA, CLI
– OLTP Specific : ATMI ( Tuxedo)
– Groupware Specific : MAPI, LN calls
– Object Specific : CORBA, OLE
– Internet Specific : HTTP, SSL
– Management Specific : SNMP, ORBs
Dr Phatak, IIT Bombay Distributed Applications 44
PEER TO PEER COMMUNICATION
Connection Oriented– Synchronous
Connection Less– Asynchronous, Store and Forward
Dr Phatak, IIT Bombay Distributed Applications 45
EXAMPLES OF DISTRIBUTED PARADIGM
Bank Master and Branch Power Bancs 2000 Micro Banker and Finware
Dr Phatak, IIT Bombay Distributed Applications 46
EXAMPLES OF DISTRIBUTED PARADIGM
Provide Branch Functionality When Network Non Functional
Provide Complete Customer Account and TXN Info
Attempt to Provide Retail and Commercial Functionality
Dr Phatak, IIT Bombay Distributed Applications 47
EXAMPLES OF DISTRIBUTED PARADIGM
SBI IDBI Bank ICICI Bank HDFC Bank A Malysian Bank Uses Four
Servers For Many Branches
Dr Phatak, IIT Bombay Distributed Applications 48
DISTRIBUTED INFRASTRUCTURE
Needs Indian Messaging Standards
Needs Proper Application Software Development
Needs Work Flow Changes
Dr Phatak, IIT Bombay Distributed Applications 49
BUILDING BLOCKS
OS Services – Task Preemption, Task Priority
– Semaphores, Inter process communications
– Threads Netware, NT, OS2 Warp, UNIX
Dr Phatak, IIT Bombay Distributed Applications 50
BUILDING BLOCKS
OS Services– Multi user high performance File
System
– Efficient Memory Management
– Dynamically linked run time extensions
Dr Phatak, IIT Bombay Distributed Applications 51
BUILDING BLOCKS
More O.S. Services– Ubiquitous Communications
– Network operating System Extensions
– Binary Large Objects (BLOBs)
– Global Directories
– Authentication and Authorization Services
Dr Phatak, IIT Bombay Distributed Applications 52
BUILDING BLOCKS
More O.S. Services– System Management
– Network time
– Database and Transaction Services
– Internet Services
– Object-Oriented Services
Dr Phatak, IIT Bombay Distributed Applications 53
BUILDING BLOCKS
Server Scalability Symmetric Multiprocessor
Systems (SMP) Massively Parallel Processors
based Servers (MPP) Clusters
Dr Phatak, IIT Bombay Distributed Applications 54
BUILDING BLOCKS
Client Systems Non-GUI
– ATMs, Barcode readers, cellular phones, fax machines
– Robots, Testers, Daemon Processes GUI Clients
– Graphics, Menus, Windows, dialogues
Dr Phatak, IIT Bombay Distributed Applications 55
BUILDING BLOCKS
OOUI Clients– Communicating objects
– Seamless access to information and action
Compound Documents– Live components
NextStep, Mac OS
Dr Phatak, IIT Bombay Distributed Applications 56
BUILDING BLOCKS
SHIPPABLE PLACES– Place: A visual ensemble of related
components
– Shippable Place: A mobile container
– can interact with collaborative environments
– Web, web form, Java enabled web pages, Compound Docs
Dr Phatak, IIT Bombay Distributed Applications 57
NETWORK OPERATING SYSTEMS
Provide transparency in– Location, Namespace, logon
– replication, access, time, failure Distributed Security (C2)
– Authentication, Authorisation
– Audit trails
Dr Phatak, IIT Bombay Distributed Applications 58
MORE ON SECURITY
Kerberos from Athena (MIT) Encryption, Session Key Data Encryption Standard (DES-3)
– Shared Private key RSA, DH Algorithms
– Public/Private key
Dr Phatak, IIT Bombay Distributed Applications 59
PEER TO PEER COMMUNICATION
Sockets– BSD 4.2 UNIX, 1981
– Netid.Hostid.Portid (IP + Port)
– Port (16 bit): entry point to service Transport Layer Interface (TLI)
– AT&T, 1986
Dr Phatak, IIT Bombay Distributed Applications 60
PEER TO PEER COMMUNICATION
Connection Oriented – Session based
– Virtual Circuits Connectionless
– Datagrams
Dr Phatak, IIT Bombay Distributed Applications 61
PEER TO PEER COMMUNICATION
Internet Package Exchange IPX– Based on Xerox Network Services
(XNS)
– Sequential Packet Exchange (SPX) NetBIOS, NetBEUI
– IBM, Sytec (1984), Microsoft
Dr Phatak, IIT Bombay Distributed Applications 62
PEER TO PEER COMMUNICATION
Named Pipes Remote Procedure Calls
– Locate and start Server functions
– Define and pass parameters
– Handle Security and Failures
– Data representation
Dr Phatak, IIT Bombay Distributed Applications 63
PEER TO PEER COMMUNICATION
Message Oriented Middleware (MOM)– Distributed Application Development
(DAD) needs MOM
– MOM consortium in 1993
– Queued Vs Call-return of RPC
– Provides Asynchronous Mechanism
– Ideal for Objets
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