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Chapter 9: ClientServer Database Systems

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Database Environment. Concepts ' ... Database Server Architecture. Client workstation: ... DBMS only on DB server. Application Partitioning ... – PowerPoint PPT presentation

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Title: Chapter 9: ClientServer Database Systems


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Chapter 9 The Client/Server Database Environment
3
Concepts
  • Client/server systems operate in a networked
    environment, splitting the processing of an
    application between a front-end client and a
    back-end processor.
  • client and server may reside on same computer
  • both are intelligent and programmable

4
Application Logic Components
  • Presentation logic
  • input
  • output
  • Processing logic
  • I/O processing
  • business rules
  • data management
  • Storage logic
  • data storage and retrieval
  • DBMS functions

5
File Server Architecture
  • A file server is a device that manages file
    operations and is shared by each of the client
    PCs.
  • Fat client does most processing
  • Limitations
  • whole file or table transferred to client
  • client must have full version of DBMS
  • each client DBMS must manage database integrity

6
File Server Model
FAT CLIENT
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Database Server Architecture
  • Client workstation
  • user interface, presentation logic, data
    processing logic, business rules logic
  • Database server
  • database storage, access, and processing
  • Advantages
  • less traffic, more control over data
  • Stored procedures first use of business logic at
    database server

8
Database Server Architecture(Two-Tier)
Thinner clients
DBMS only on server
9
Advantages of Stored Procedures
  • Compiled SQL statements
  • Reduced network traffic
  • Improved security
  • Improved data integrity
  • Thinner clients

10
Three-Tier Architectures
  • Application server in addition to client and
    database server
  • Thin clients do less processing
  • Application server contains standard programs
  • Benefits
  • scalability
  • technological flexibility
  • lower long-term costs
  • better match business needs
  • improved customer service
  • competitive advantage
  • reduced risk

11
Three-Tier Architecture
Thinnest clients
Business rules on separate server
DBMS only on DB server
12
Application Partitioning
  • Where should modules be placed on the client or
    on the application server?

13
Mainframes and Parallel Computer Architectures
  • Mainframes hold legacy data and systems
  • good for multiuser, massive data access
  • Parallel architectures
  • parallel transaction (two users)
  • parallel query (one user, split processing)
  • symmetric multiprocessing (SMP) (share memory)
  • massively parallel processor (MPP) (share
    nothing)
  • Consider
  • large amounts of data, complex queries, large
    number of users
  • cost analyze as part of initiative that it
    supports
  • can current technology do the job?

14
Middleware
  • Software that allows interoperability
  • asynchronous remote procedure call (RPC)
  • publish/subscribe
  • message oriented middleware (MOM)
  • object request brokers (ORB)
  • SQL-oriented data access
  • synchronous RPC
  • Client/server middleware
  • application program interface (API)
  • open database connectivity (ODBC)
  • java database connectivity (JDBC)
  • common object request broker architecture (CORBA)
  • Distributed Component Object Model (DCOM)

15
Security
  • System-level password
  • who can be on the system?
  • Database-level password
  • who can use the data? (or a given program?)
  • Client/server communication
  • encrypted data transfer

16
Query by Example (QBE)
  • No official standard
  • First pass at SQL
  • Interactive querying or updating
  • Usability hierarchy
  • objects
  • functions/expressions
  • macros
  • VBA
  • API

17
Building Queries using QBE
  • Visual image of the table is used for writing
    queries.
  • Result is a dynaset
  • not a base table
  • dynamic or virtual set
  • may or may not be updateable
  • Joins (relationships) based on relationship view
    or created in query

18
Joins
  • Inner (normal) join
  • instructors and sections they teach
  • Outer join
  • all classes and scheduled sections
  • Self join
  • students and their advisors

19
Access Query Types
  • Select
  • SQL
  • Total ? group by, aggregate functions
  • Action create, delete, update, append
  • Crosstab
  • Top(n)

20
Reports
  • Banded report design
  • report header
  • page header
  • group header repeatable
  • detail
  • group footer
  • page footer
  • report footer

21
Visual Basic for Applications (VBA)
  • Benefits
  • complex functionality
  • error handling
  • faster execution
  • maintenance
  • OLE automation
  • more programmatic control
  • easier to read
  • Event-driven
  • event occurs
  • event detected
  • response generated

22
Chapter 10 The Internet Database Environment
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Near or Far
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Getting the Data
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Chapter 11 Data Warehouse
  • Subject-Oriented
  • Integrated
  • Time-Variant
  • Nonupdatable

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Two Types of Processing
  • Operational processing
  • captures, stores, and manipulates data to support
    daily operations
  • Informational processing
  • analysis of summarized data to support decision
    making
  • Data warehouses
  • consolidate and integrate information from many
    different sources and arrange it in a meaningful
    format for making accurate business decisions

27
Data Warehouse Architectures
  • Two-level architecture
  • source files read-only data warehouse
  • Three-level architecture
  • source files enterprise data warehouse
    (reconciled data) data mart (derived data)

28
Data Characteristics
  • Status vs. event data
  • balance vs. transaction
  • Transient vs. periodic data
  • current balance vs. balance history

29
Reconciled Data Layer
  • Used to build data warehouse
  • Characteristics of reconciled data
  • detailed
  • historical
  • normalized
  • comprehensive
  • quality controlled
  • Capture ? Scrub ? Transform ? Load

ETL Extract, transform, and load
30
Derived Data Layer
  • Data that have been selected, formatted, and
    aggregated
  • Star schema
  • dimension table demographic data
  • fact table associative data often summarized

Customer
Cruise
Reservation
Agent
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User Interface
  • Traditional query and reporting tools
  • On-line analytical processing (OLAP)
  • cube slicing
  • drill-down
  • Data mining
  • explanatory
  • confirmatory
  • exploratory
  • Data visualization

32
Slicing the Cube
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