Download Chapter 12 - Emunix Documentation on the Web

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Chapter 12
Working With
Access 2000 on the
Internet
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Chapter Objectives
• Review hyperlinks, HTML, and cascading
style sheets
• Learn about data access pages
• Explore server-side sorting and filtering
• Learn about scripts and Active Server Pages
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Working With Access 2000 on
the Internet
• Two ways exist to link to Access 2000
database to a Web application:
 Use the Data Access Page (DAP) object that
exists in Access 2000
 Use Active Server Pages (ASP) technology
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Hyperlinks
• Hyperlink field
 Contains the specification for a universal
resource locator (URL)
 Created in a table simply by choosing the
hyperlink data type as the field format for the
attribute when you are designing the table
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Hyperlinks
• Two properties that can be manipulated:
 Hyperlink Address
 Specifies the URL
 May designate a specific file on a local network or a
local hard drive
 Hyperlink SubAddress
 May specifies a specific form within the database
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HTML
• Hypertext Markup Language (HTML)
 Not a programming language, but a formatting
language
 Access 2000 permits tables, forms, reports, and
queries to be saved in an HTML format
 Static file
 When working with forms, only a form’s Datasheet
view can be saved as HTML
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Cascading Style Sheets
• Cascading style sheets (CSS)
 Make it easier to change page formats
 Contains the definition of various format
properties
 Can be used to format Web pages
 If a change is made in the CSS, then all of the Web
pages using it will reflect the change
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Working With
Data Access Pages
• Data access pages
 External files that provide a means to use
Access 2000 on the Internet
 Stored as separate HTML files
• To preview a page as it would appear in a
browser, right-click the shortcut in the
Database window and choose Web Page
Preview
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Working With
Data Access Pages
• You can change the appearance of a data
access page:
 Themes
 Formatting templates
 Add text, labels, and controls
 Add a picture or other image file as data in an
OLE Object field
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Data Access Page Properties
• To view a data access page’s properties, click the
title bar of the data access page after opening the
Properties window
Figure 12-1
Property sheet for a
data access page
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Data Access Page Properties
• Properties of a data access page:
 DataEntry
 Controls whether new records can be added to the
underlying table
 MaxRecords
 Allows you to designate the number of records sent
to a client computer from a server
 RecordType
 Determines whether a recordset is updateable
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The Record Navigation
Control
• Record navigation control
 Unique to data access pages
 Provides the capability to perform many tasks
involving record navigation, record creation
and deletion, and record sorting
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The Record Navigation
Control
Figure 12-2
Record
navigation
control
instance
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Grouping Data in
Data Access Pages
• Grouping data on a data access page is
similar to grouping data on a report with a
sub-report except:
 Data displayed is dynamic
 Data access pages are interactive
 Data access pages that display grouped data are
read-only
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Grouping Data in
Data Access Pages
• Group properties:
 Expanded by Default
 When set to Yes, the data access page automatically
displays the data within a grouping
 Data Page Size
 Settings determines the maximum number of
records to display within a particular grouping level
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Grouping Data in
Data Access Pages
Figure 12-3
Expand control
instance on a
grouped data
access page
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Server-Side Sorting and
Filtering
• Server-side sorting and filtering can save time
when downloading data to the client
• Establish a default server-side sort order by setting
the Default Sort property in the Sorting and
Grouping dialog box
• When Access publishes a page as an Active Server
Page, a server filter can be applied to perform the
filtering operation on the server
 Only the filtered data are downloaded
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Scripts and Access 2000
• You can associate VBA program code with
events to customize an application in an
Internet environment
 VBScript is a variation of VBA that works with
Internet Explorer 5
 Does not recognize VBA
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Scripts and Access 2000
• VBScript differs from VBA in several ways:
 All variables in VBScript are variants
 Arguments passed to procedures and functions
cannot be typed
 Many functions found in VBA are not available
in VBScript
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Scripts and Access 2000
• VBScript differs from VBA in several ways:
 Error-handling capabilities are not as
sophisticated in VBScript
 Symbolic constants are not predefined
 To use them, you must create a file and include it
yourself
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Scripts and Access 2000
• Certain data access page events are not
recognized when coded in JavaScript and
script elements are case-sensitive in
JavaScript
• You can add scripts by choosing Tools,
Macros, and the Microsoft Script Editor
from the menu bar
 Displays the Microsoft Development
Environment window
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Scripts and Access 2000
Figure 12-5
Microsoft
Development
Environment
window
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Scripts and Access 2000
• When you connect an Active Server Page to
an Access 2000 database
 Include a file, named adovbs.inc, that contains
predefined symbolic constants to facilitate
establishing the database connection
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Active Server Pages and
Access 2000
• Active Server Pages (ASP)
 Implemented as an Internet Server application
programming interface (ISAPI) filter running
under Microsoft’s Internet Information Server
(IIS)
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Scripts and Access 2000
• Whenever a Web client sends an HTTP
request to a Web server:
 The Active Server ISAPI filter has a chance to
intercept and interpret the request
• If the request involves an ASP file:
 The filter parses the entire file and returns
HTML output to IIS
 IIS then returns these data to the client
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Scripts and Access 2000
• To implement ASP, you must have a Web
server configured to support the technology
• System data source
 Data source that is accessible to all user
 ODBC 32 control panel on the server is used to
establish an Access database such as a system
data source
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Using the Global.asa File
• Global.asa file performs two functions:
 Indicates where the scripts will be executed
 In many cases, it takes place on the server to take
advantage of the processing power typically
available there
 Amount of data transferred to the client can be
minimized
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Using the Global.asa File
• Global.asa file performs two functions
(continued):
 Implements scripts associated with four specific
events
 Events that occur for the Application and Sessions
objects
• Application object
 Created when the application runs
 Responds to the OnStart and an OnEnd event
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Using the Global.asa File
• Session object
 Separate object is created for each user of the
application
 Responds to its own OnStart and OnEnd events
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Variables and the OnStart
Event
• OnStart event of the Application object
 Used to initialize or update variables used by
the application
• Variables may include the number of users
of the application or the number of users
who have visited the Web site since the
application started
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Variables and the OnStart
Event
• OnStart event for the Session object
 Initializes variables for a particular user’s
session
 Timeout variable
 Indicates how long a session is allowed to be idle
before it is automatically terminated by the server
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Session Variables in ASP
• Session variable
 Can declare any number of Session variables
simply by using them
 Available to all ASP files that execute during
the session
 Acts like a global variable in other
programming languages
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The OnEnd Event
• OnEnd event for the Application object
 Occurs when the application ends
• OnEnd event for the Sessions object
 Occurs when the session ends
 Used to update persistent data relevant to the
application
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Chapter Summary
• Access 2000 provides several ways to
create Web-enabled database applications
 Hyperlink data type
 Fundamental Web-enabling object
 New capabilities with the Access development
environment for developing Web-enabled
applications
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Chapter Summary
• DAP objects
 Not totally contained in the .mdb file associated
with an Access application
• Data access page
 Web page that must be accessible by a server
 Web pages must be saved as an HTML file outside
the .mdb file
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Chapter Summary
• Data access pages (continued)
 Created in much the same manner as forms or
reports
 Same toolbox is used for their creation
 Contains additional, Web-specific tools for
operations such as creating a bound HTML control
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Chapter Summary
• VBScript
 Variation of VBA
• Active Server Pages
 Provides an environment in which VBScript
and embedded SQL commands can be used to
access data in Access databases and to create
Web pages dynamically