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Chapter 14 Databases and The Internet


Chapter 14 Databases and The Internet Database Systems: Design, Implementation, and Management 4th Edition Peter Rob & Carlos Coronel – PowerPoint PPT presentation

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Title: Chapter 14 Databases and The Internet

Chapter 14 Databases and The Internet
Database Systems Design, Implementation, and
Management 4th Edition Peter Rob Carlos Coronel
Internet Technologies and Databases
  • To support the global business reach, IS
    departments must ensure the integration of
    databases and their components and universal
    access to them from anywhere in the world.
  • Internet technologies provide unparalleled
    advantages because the Internet is a global
    network that provides universal access through an
    interface known as a Web browser, which is easy
    to use and runs on multiple platforms.
  • For IS departments, the new frontier is the use
    of Internet technologies to facilitate database
    access and to provide services to customers,
    partners, employees, and the general public.

Characteristics And Benefits Of Internet
Table 14.1
A Sample Of Applications That Use Internet
Table 14.2
Table 14.3
Basic Components Of The World Wide Web
Figure 14.1
Intranets and Extranets
  • Intranets
  • An Intranet is a locally owned and operated
    Internet whose access is carefully controlled.
    Its objective is to enhance company operations
    through improved data access management.
  • Intranets provide a platform for the development
    of new systems in a timely and cost-effective
  • Intranets are relatively easy to set up and to
    implement at the technical level. Once
    implemented, intranet services tend to grow
  • Extranets
  • If an intranet extends beyond a single corporate
    entity, it is known as an extranet.
  • An extranet extends the intranets to the
    corporations value chain.

Intranet/Extranet Components
Figure 14.2
Intranets and Extranets
  • Intranet/Extranet Advantages
  • Open standards
  • Platform independence and portability
  • Support for multiple data sources and types
  • Process distribution and scalability
  • Ease of use
  • Shorter development times and reduced costs
  • Development tools that are integrated through the
    use of open standards
  • The universal client provides a common interface
    to all services
  • Communications infrastructure

Intranet Architecture
Common Intranet Services
  • Web server
  • Electronic mail
  • Document search
  • File Transfer Protocol (FTP)
  • News or discussion groups
  • Workflow and team collaboration
  • Web-to-database services
  • Transaction processing
  • Directory, security, and authentication services
  • Firewalls and proxy servers
  • Load balancing and caching
  • Web-to-host access

A Multitier Intranet Architecture
Figure 14.3
Intranet Architecture
  • Server-Side Extensions Web-to-Database
  • A server-side extension is a program that
    interacts directly with the Web server to handle
    specific types of requests.
  • A database server-side extension program is also
    known as Web-to-database middleware.

Figure 14.4 Web-To-Database Middleware
Intranet Architecture
  • Web Server Interfaces
  • Two Web well-defined server interfaces
  • Common Gateway Interface (CGI)
  • The CGI uses script files that perform specific
    functions based on the clients parameters that
    are passed to the Web servers.
  • The script file is a small program containing
    commands written in some programming language
    (e.g., PERL, C, or Visual Basic)
  • Application programming interfaces (APIs)
  • APIs are a newer Web server interface standard
    that is much more efficient and faster than CGI
  • APIs are implemented as shared code or as
    dynamic-link libraries (DLLs).

The API And CGI Web Server Interfaces
Figure 14.5
Intranet Architecture
  • Open Database Connectivity (ODBC)
  • ODBC is Microsofts implementation of a superset
    of the SQL Access Group Call-Level-Interface
    (CLI) standard for database access.

Figure 14.6
(No Transcript)
Intranet Architecture
  • The Web Browser
  • The Web browser is located in the client computer
    and it is the end user interface to the Web.
  • The Web browsers job is to interpret the HTML
    code that it receives from the Web server and to
    present the different page components in a
    standard way.
  • The browsers interpretation and presentation
    capabilities are not sufficient to develop
    Web-based applications, requiring plug-ins and
    other client-side extensions.

Intranet Architecture
  • Client-Side Extensions
  • Plug-ins
  • A plug-in is an external application that is
    automatically invoked by the browser when needed.
  • The plug-in is OS specific.
  • The plug-in is associated with a data object to
    allow the Web server to properly handle data that
    are not originally supported.
  • Java
  • Java is an object-oriented programming language
    developed by Sun Microsystems that run on top of
    the Web browser software.
  • Java applications are compiled and stored in the
    Web server.
  • Calls to Java routines are embedded inside the
    HTML page.

Intranet Architecture
  • JavaScript
  • JavaScript, developed by Netscape, is a scripting
    language that allows Web authors to design
    interactive sites.
  • JavaScript code is embedded in the Web pages.
  • The embedded JavaScript is downloaded with the
    Web page and is activated when a specific event
    takes place.
  • Active X
  • Active X is Microsofts alternative to Java. It
    is a specification for writing programs that will
    run inside the Microsoft client browser.
  • Active X extends the browser by adding controls
    to Web pages. These controls can be downloaded
    from the Web server and let the user manipulate
    data inside the browser.

Intranet Architecture
  • VBScript
  • VBScript is another Microsoft product that is
    used to extend the browser's functionality.
  • VBScript is derived from Visual Basic.
  • VBScript code is embedded inside an HTML page and
    this code is activated by triggering events such
    as clicking on a link.

Using A Web-to-DB Production Tool ColdFusion
  • ColdFusion application middleware can be used to
  • Connect to and query a database from a Web page.
  • Present database data in a Web page, using
    various formats.
  • Create dynamic Web search pages.
  • Create Web pages to insert, update, and delete
    database data.
  • Define required and optional relationships.
  • Define required and optional form fields.
  • Enforce referential integrity in form fields.
  • Use simple and nested queries and form select
    fields to represent business rules.

How ColdFusion Works
Figure 14.8
The RobCor Databases Relational Schema
Figure 14.9
Using A Web-to-DB Production Tool ColdFusion
  • Creating a Simple Query with CFQuery and CFOutput
  • Tasks
  • Query the database, using standard SQL to
    retrieve a data set that contains all records
    found in the VENDOR table.
  • Format all of the records generated in Step 1 in
    HTML to let them be included in the page that is
    returned to the client browser.
  • See Script 14.1 for the script and Figure 14.10
    for the output.

Script 14.1 A Simple Query Using CFQUERY And
The CH14-1.CFM Script Output
Figure 14.10
Script 14.2
The CH14-2.CFM Script Output
Figure 14.11
Using A Web-to-DB Production Tool ColdFusion
  • Creating a Simple Query with CFQuery and CFTable
  • Task
  • Perform the same query with the result presented
    in tabular format.
  • See Script 14-3 and Figure 14.12

Script 14.3 CFQUERY With CFTABLE
The CH14-3.CFM Script Output
Figure 14.12
Using A Web-to-DB Production Tool ColdFusion
  • Creating a Dynamic Search Page
  • Two steps to create a dynamic query
  • 1. Create a script that will generate a form
  • 2. Create a script that will execute the query
    and display the results based on the parameters
    that are passed to it by the script created in
    Step 1.
  • See Script 14.4A and Figure 14.13

Script 14.4A Dynamic Search Query Criteria
Entry Form
The CH14-4A.CFM Script Output
Figure 14.13
Script 14.4B The Vendor Search Results
The CH14-4B.CFM Script Output1OP4.062
Figure 14.14
The Vendor List For the Condition VEN_STATE GA
Figure 14.15
Using A Web-to-DB Production Tool ColdFusion
  • The Web as a Stateless System
  • The Web is said to be a stateless system because
    the Web does not reserve memory to maintain an
    open communications state between the client
    and the server.
  • The browser does not have computational abilities
    beyond formatting output text and accepting form
    field inputs.
  • To perform processing (e.g., data entry) in the
    client, the Web defers to other Web-programming
    languages such as Java, JavaScript, VBScript, etc.

Script 14.5A The Insert Query Data Entry Screen
Figure 14.16 The CH14-5A.CFM Script Output
Figure 14.17 The Insert Query Form Server-Side
Validation Error Message
The Insert Query Confirmation Screen
Script 14.5B
The CH14-5B.CFM Script Output
Figure 14.18
The Insert Query ODBC Integrity Violation Error
Figure 14.19
Using A Web-to-DB Production Tool ColdFusion
  • Data Updates
  • Three pages required to update data
  • The first page (Script 14-6a) will allow the end
    user to select the record to be updated. When the
    user clicks on the Edit button, the second page,
    produced by Script 14-6b, is called and the first
    pages search field value is passed to this
    second page.
  • The second page (Figure 14-20) will read the
    selected record, then display a data entry form
    to enable the end user to modify the data.
  • The third page (Script 14-6c) will update the
    data in the database and present a confirmation

Script 14.6A The Update Query Record
Selection Screen
The CH14-6A.CFM Script Output
Figure 14.20
Script 14.6B The Update Query Edit Record Screen
The CH14-6B.CFM Script Output
Figure 14.21
Update Query Result Confirmation Screen
Script 14.6C
The CH14-6C.CFM Script Output
Figure 14.22
Using A Web-to-DB Production Tool ColdFusion
  • Deleting Data
  • Three pages required to delete data
  • The first page (Script 14-7a) will allow the end
    user to select the record that is to be deleted.
    When the user clicks the forms Delete button,
    Script 14-7b is invoked, and the DEPT_ID form
    field value is passed to it.
  • The second page (Script 14-7b) will read the
    selected record and display its data on the
  • The third page (Script 14-7c) will delete the
    department row from the database table, using the
    DEPT_ID form field value passed from its calling

Script 14.7A Delete Query Record Selection
The CH14-7A.CFM Script Output
Figure 14.23
Script 14.7B Delete Query Show Record Screen
The CH14-7B.CFM Script Output
Figure 14.24
Delete Query Result Confirmation Screen
Script 14.7C
The CH14-7C.CFM Script Output
Figure 14.25
The Delete Record Validation
Figure 14.26
Internet DB Systems Special Considerations
  • What Data Types Are Supported?
  • How does one store and extract data objects such
    as documents, pictures, and movies through a Web
  • How much overhead will be created by the storage
    of binary objects in the database? How robust
    must the DBMS be to handle binary object
    transactions? What are the limitations for
    extended or OLE data types? How many extended or
    OLE data type fields can tables have?
  • Does the client browser support the data type of
    the object you are trying to access? Are the
    necessary plug-ins available? Is there a way to
    automatically translate documents from their
    native format to HTML?
  • Does the DBMS support Very Large Databases? What
    about transaction speed? How many users are going
    to access the database? How often?

Internet DB Systems Special Considerations
  • Data Security
  • Security can be implemented in the Web server,
    the database and in the networking
  • At the Web server level, most Web clients and
    servers can perform secure transactions by using
    encryption routines at the TCP/IP protocol level.
  • At the SQL level, administrators can use the
    GRANT and REVOKE commands to assign access
    restrictions to tables and/or to specific SQL
  • Web-to-database middleware vendors usually have
    several security mechanisms available to
    interface with databases.

Internet DB Systems Special Considerations
  • Transaction Management
  • The designers must ensure proper transaction
    management support at the database server level
    since the Web does not support the concept of
    database transaction
  • The Web cannot maintain an open line between the
    client and the database server.
  • The mechanics of a recovery from incomplete or
    corrupted database transactions require that the
    client must maintain an open communications line
    with the database server.

Internet DB Systems Special Considerations
  • Denormalization of Database Tables
  • The Web environment does not support multitable
    (parent-child) data entry.
  • Although implementing the parent/child data entry
    is not impossible in a Web environment, its final
    outcome is less than optimum, counterintuitive,
    less user-friendly, and prone to errors.
  • Web programming languages such as Java,
    JavaScript, or VBScript can be used to create the
    required Web interfaces.