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Client Server TechnologiesMiddleware Technologies
Ganesh PanchanathanAlex Verstak
Overview Ganesh
Client/Server technologies Middleware
Alex DirectExchange Sequoia 2000 3-Tier Architecture on the Grid
Computing models Terminal host model
File sharing model Client/Server model Peer to Peer model
Client/Server model
Client/server model is a concept for describingcommunications between computing
processesthat are classified as service consumers
(clients)and service providers (servers).
2 Tier 3 Tier N Tier
Two Tier C/S Architecture
Layers Clients Servers
Functionalities User Interface – Client Business Logic – Client (Server??) Database management – Server
3 Tier C/S Architecture Presentation Tier Business Tier Database Tier
2 Tier vs. 3 Tier Modularity Change management Reuse Performance Scalability Multiple data sources ????
Example N-Tier Architecture
J2EE Application Model
Middleware
Middleware is a class of softwaretechnologies designed to help
managethe complexity and heterogeneityinherent in distributed systems.
Middleware
Middleware
Enable multiple processes interact across a network
Between Apps and OS/Network services
More functional API for: Heterogeneity Location transparency Reliability Scalability
Types of middleware
Middleware can take the following forms:
Remote procedure call Object request broker Transaction Processing monitor Message oriented middleware
Transaction
A Transaction means a sequence ofinformation exchange and related
work(such as database updating) which istreated as an unit for the purposes ofsatisfying a request and ensuringdatabase integrity.
Examples of transactions
Purchase online using credit card Withdraw money from ATM Electronic funds transfer Book an airline ticket Ordering in Inventory management Billing for phone calls
Transactional Integrity - ACID
Atomicity Trans. must be done or undone
completely Consistency
One consistent state to another Isolation
Each trans. must be independent of others Durability
Completed transactions are permanent
Transaction Processing MonitorMonitors a transaction as it passesthrough the different stages to
Guarantee integrity of transaction Runtime resource management
TP Monitors Clients connect to the TP monitor TP Monitor
Accepts transactions Queues them Takes responsibility till they are
finished Two types
TP Heavy TP Lite
Features Maps requests to controlled set of
processing routines for performance
Ability to update multiple DBMSs in a single transaction
Connectivity to flat files, non relational DB and legacy data
Prioritize transactions
Vendor Implementations Tuxedo by BEA JTS by Java MTS by Microsoft CICS by IBM
Message Oriented MiddlewareMessaging is an asynchronous method ofpassing information between processes
across network across platform and OS
Message Oriented middleware
Message – Self contained object Message header – address, id, priority Body of the message
Message is intelligent when compared to a transaction in TP systems.
In TP systems Transactions are just packets Intelligence to handle them is in monitor
Message Oriented Middleware
Features of MOM Primarily asynchronous communication Point to multi-point Ordered delivery Receipt notification Handling duplicates Message queues – FIFO or priority basis Messages – persistent or non-persistent
Point to point messaging Client may be only sender, only
receiver or both
Single receiver Use of a message queue
Publish – Subscribe messaging Free sender from knowing the
receivers Messages are categorized on
topics List of senders/receivers is
dynamic
Vendor Offerings MQSeries by IBM JMS by Java MSMQ by Microsoft DECMessageQ by BEA
References Client/Server
http://edocs.bea.com/tuxedo/tux80/atmi/intbas3.htm http://www.sei.cmu.edu/str/descriptions/clientserver.html http://www.sei.cmu.edu/str/descriptions/threetier.html
Middleware http://www.sei.cmu.edu/str/descriptions/middleware.htm http://www.eecs.wsu.edu/~bakken/middleware.pdf http://www.execpc.com/~gopalan/mts/msmq.html http://proj-cmw.web.cern.ch/proj-cmw/workshop/
mom.pdf