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CLIENT-SERVER AND DISTRIBUTED DATA BASES - Coggle Diagram
CLIENT-SERVER AND
DISTRIBUTED DATA BASES
client
a program that makes requests to a server
server
•performs requests and communicates results
to the clients
Two-Tier Architecture
The validation and business logic code can be split
between the PC client and the database server
positive
is the simplest to implement
negative
software maintenance can be difficult
Three-Tier Architecture
transaction-processing monitor may
support more simultaneous connections
message-oriented middleware provides more
flexibility
additional server software can reside on a separate computer
additional server software can be distributed between the
database server and PC clients
Multiple-Tier Architecture
The application servers can be invoked from PC clients, middleware,
and database servers
Web Services Architecture
deploying services faster
communicating new services in standard formats
finding existing services from other organizations
electronic business commerce
Distributed Database Architecture.
A site
geographically distributed
any locally controlled computer with a unique network
address
Global requests
are queries that combine data from more than one site
and transactions that update data at more than one site
can involve a collection of statements accessing local
data in some statements and remote data in other statements
Distributed database managers
optimizes query execution across
sites
coordinates concurrency control and recovery
controls access to remote data
tight integration
loose integration
Local database managers
provide complete features of a DBMS
homogeneous
heterogeneous