14 Chapter 14 Databases and The Internet Database Systems: Design, Implementation, and Management 4th Edition Peter Rob & Carlos Coronel.
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14 Chapter 14 Databases and The Internet Database Systems: Design, Implementation, and Management 4th Edition Peter Rob & Carlos Coronel
14 Internet Technologies and Databases 4To 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. 4Internet 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. 4For 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.
14 Characteristics And Benefits Of Internet Technologies Table 14.1
14 A Sample Of Applications That Use Internet Technology Table 14.2
14 Basic Components Of The World Wide Web Figure 14.1
14 Intranets and Extranets 4Intranets u 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. u Intranets provide a platform for the development of new systems in a timely and cost-effective manner. u Intranets are relatively easy to set up and to implement at the technical level. Once implemented, intranet services tend to grow exponentially. 4Extranets u If an intranet extends beyond a single corporate entity, it is known as an extranet. u An extranet extends the intranets to the corporation’s value chain.
14 Intranets and Extranets 4Intranet/Extranet Advantages u Open standards u Platform independence and portability u Support for multiple data sources and types u Process distribution and scalability u Ease of use u Shorter development times and reduced costs u Development tools that are integrated through the use of open standards u The universal client provides a common interface to all services u Communications infrastructure
14 Intranet Architecture 4Web server 4Electronic mail 4Document search 4File Transfer Protocol (FTP) 4News or discussion groups 4Workflow and team collaboration 4Web-to-database services 4Transaction processing 4Directory, security, and authentication services 4Firewalls and proxy servers 4Load balancing and caching 4Web-to-host access Common Intranet Services
14 A Multitier Intranet Architecture Figure 14.3
14 Intranet Architecture 4Server-Side Extensions: Web-to-Database Middleware u A server-side extension is a program that interacts directly with the Web server to handle specific types of requests. u A database server-side extension program is also known as Web-to-database middleware.
14 Intranet Architecture 4Web Server Interfaces u Two Web well-defined server interfaces: l Common Gateway Interface (CGI) –The CGI uses script files that perform specific functions based on the client’s 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) l Application programming interfaces (APIs) –APIs are a newer Web server interface standard that is much more efficient and faster than CGI scripts. –APIs are implemented as shared code or as dynamic- link libraries (DLLs).
14 The API And CGI Web Server Interfaces Figure 14.5
14 Intranet Architecture 4Open Database Connectivity (ODBC) u ODBC is Microsoft’s implementation of a superset of the SQL Access Group Call-Level-Interface (CLI) standard for database access. Figure 14.6
Intranet Architecture 4The Web Browser u The Web browser is located in the client computer and it is the end user interface to the Web. u The Web browser’s 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. u The browser’s interpretation and presentation capabilities are not sufficient to develop Web- based applications, requiring plug-ins and other client-side extensions.
14 Intranet Architecture 4Client-Side Extensions u Plug-ins l A plug-in is an external application that is automatically invoked by the browser when needed. l The plug-in is OS specific. l The plug-in is associated with a data object to allow the Web server to properly handle data that are not originally supported. u Java l Java is an object-oriented programming language developed by Sun Microsystems that run on top of the Web browser software. l Java applications are compiled and stored in the Web server. l Calls to Java routines are embedded inside the HTML page.
14 Intranet Architecture u VBScript l VBScript is another Microsoft product that is used to extend the browser's functionality. l VBScript is derived from Visual Basic. l VBScript code is embedded inside an HTML page and this code is activated by triggering events such as clicking on a link.
14 Using A Web-to-DB Production Tool: ColdFusion 4ColdFusion application middleware can be used to: u Connect to and query a database from a Web page. u Present database data in a Web page, using various formats. u Create dynamic Web search pages. u Create Web pages to insert, update, and delete database data. u Define required and optional relationships. u Define required and optional form fields. u Enforce referential integrity in form fields. u Use simple and nested queries and form select fields to represent business rules.
14 The RobCor Database’s Relational Schema Figure 14.9
14 Using A Web-to-DB Production Tool: ColdFusion 4Creating a Simple Query with CFQuery and CFOutput u Tasks: l Query the database, using standard SQL to retrieve a data set that contains all records found in the VENDOR table. l 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. u See Script 14.1 for the script and Figure 14.10 for the output.
14 Script 14.1 A Simple Query Using CFQUERY And CFOUTPUT
14 Using A Web-to-DB Production Tool: ColdFusion 4Creating a Simple Query with CFQuery and CFTable u Task: l Perform the same query with the result presented in tabular format. u See Script 14-3 and Figure 14.12
14 Using A Web-to-DB Production Tool: ColdFusion 4Creating a Dynamic Search Page u 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. u See Script 14.4A and Figure 14.13
14 Script 14.4A Dynamic Search Query: Criteria Entry Form
14 The CH14-4B.CFM Script Output1OP4.062 Figure 14.14
14 The Vendor List For the Condition VEN_STATE = “GA” Figure 14.15
14 Script 14.5A The Insert Query Data Entry Screen
14 Figure 14.16 The CH14-5A.CFM Script Output Figure 14.17 The Insert Query Form: Server-Side Validation Error Message
14 The Insert Query Confirmation Screen Script 14.5B
14 Using A Web-to-DB Production Tool: ColdFusion 4Data Updates u Three pages required to update data l 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 page’s search field value is passed to this second page. l 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. l The third page (Script 14-6c) will update the data in the database and present a confirmation message.
14 Script 14.6A The Update Query: Record Selection Screen
14 Using A Web-to-DB Production Tool: ColdFusion 4Deleting Data u Three pages required to delete data l 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 form’s Delete button, Script 14-7b is invoked, and the DEPT_ID form field value is passed to it. l The second page (Script 14-7b) will read the selected record and display its data on the screen. l 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 program.
14 Script 14.7A Delete Query Record Selection Screen
14 Internet DB Systems: Special Considerations 4What Data Types Are Supported? u How does one store and extract data objects such as documents, pictures, and movies through a Web browser? u 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? u 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? u Does the DBMS support Very Large Databases? What about transaction speed? How many users are going to access the database? How often?
14 Internet DB Systems: Special Considerations 4Data Security u Security can be implemented in the Web server, the database and in the networking infrastructure. u At the Web server level, most Web clients and servers can perform secure transactions by using encryption routines at the TCP/IP protocol level. u At the SQL level, administrators can use the GRANT and REVOKE commands to assign access restrictions to tables and/or to specific SQL commands. u Web-to-database middleware vendors usually have several security mechanisms available to interface with databases.
14 Internet DB Systems: Special Considerations 4Transaction Management u The designers must ensure proper transaction management support at the database server level since the Web does not support the concept of database transaction: l The Web cannot maintain an open line between the client and the database server. l 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.