Week 7 Lecture Web Database Development Samuel Conn, Asst. Professor Professor’s Notes In this lecture you will study how databases can be used on the world wide web. Implementation of database applications on the Internet is proliferating at an amazing rate, and the need for Internet database administration continues to grow. The lecture covers the basics of web database development. Samuel Conn, Asst. Professor

In this lecture, you will learn: How Internet databases are typically used About the architecture of Web-to-database middleware How Web-to-database middleware is used to integrate databases with the Internet What special considerations govern Web database development 2 In this lecture, you will learn: How Internet databases are typically used About the architecture of Web-to-database middleware How Web-to-database middleware is used to integrate databases with the Internet What special considerations govern Web database development Here are the key points to be covered in this lecture. You will study how Internet databases are used, the middleware architecture used to implement databases on the web, and the special considerations that are associated with web database development. 2

Web Database Connectivity Allows rapid response to competitive pressures New services New products Customer support enhanced Fast effective information dissemination Universal access Local Around the globe 3 Web Database Connectivity Allows rapid response to competitive pressures New services New products Customer support enhanced Fast effective information dissemination Universal access Local Around the globe Connecting your businesses database to the web can offer several advantages. New services and products can be quickly introduced to the marketplace. Customer support can be enhanced and Customer Relationship Management (CRM) applications can be used. It is also a great way to deliver information around the world. 3

Typical Uses of Internet 4 Typical Uses of Internet Table 15.2 Here are some of the typical uses of the Internet in the facilitation of business processes…… Table 15.2 4

Characteristics/Benefits of Internet Technology Hardware & software independence Cost savings Uses existing equipment Platform independence and portability No need for multiple platform development Common simple user interface Reduced training Reduced support 5 Characteristics/Benefits of Internet Technology Hardware & software independence Cost savings Uses existing equipment Platform independence and portability No need for multiple platform development Common simple user interface Reduced training Reduced support Internet technology has several benefits and distinguishing characteristics. It is independent of hardware and software that currently exists in the business enterprise. You can use existing equipment and develop into the Internet as an extension of your existing platform. The user interface is essentially thin client technology, and requires no special support or training. 5

Characteristics/Benefits of Internet Technology (con’t.) Location Independence Global access through Internet Reduced costs for dedicated connections Rapid development at manageable costs Development tools Low entry costs Available software & access tools 6 Characteristics/Benefits of Internet Technology (con’t.) Location Independence Global access through Internet Reduced costs for dedicated connections Rapid development at manageable costs Development tools Low entry costs Available software & access tools You can have locations around the globe, so geographic location is not a barrier. And you can develop and implement on the web very quickly and with relatively low cost. 6

Web-to-Database Middleware Server-side extension Interacts directly with Web server Handles specific requests Also known as Web-to-database middleware Examples ColdFusion CGI API 7 Web-to-Database Middleware Server-side extension Interacts directly with Web server Handles specific requests Also known as Web-to-database middleware Examples ColdFusion CGI API The extension of an existing infrastructure to the web is a “server-side” extension done through the use of certain software, called middleware, that creates the interface between the web access and the local database application. 7

Web-to-Database Middleware 8 Web-to-Database Middleware Figure 15.1 Here is a good illustration of how middleware is used to interface a backend database application with users around the world coming in through the Internet. Figure 15.1 8

Web Server Interfaces Common Gateway Interface (CGI) Uses script files to connect to database Perl, C++, VB Application Programming Interface (API) Newer and more efficient Uses DLLs Memory resident and faster Well known APIs Netscape (NSAPI) Internet Server API from Microsoft (ISAPI) WebSite API from O’Reilly (WSAPI) 9 Web Server Interfaces Common Gateway Interface (CGI) Uses script files to connect to database Perl, C++, VB Application Programming Interface (API) Newer and more efficient Uses DLLs Memory resident and faster Well known APIs Netscape (NSAPI) Internet Server API from Microsoft (ISAPI) WebSite API from O’Reilly (WSAPI) Some of the common, but older, methods of interfacing applications to the web are technologies known as Common Gateway Interface, or CGI. CGI uses some type of programming script language, usually Perl, C++, or Visual Basic to connect to the database from the web. New technologies create an Application Programming Interface, or API, that is more efficient and faster. 9

API and CGI Web Server Interfaces 10 API and CGI Web Server Interfaces Figure 15.2 Here is an illustration that shows how both APIs and CGI interfaces can connect the web user to a database application. Figure 15.2 10

Web-to-Database Middleware Connection Methods Native SQL access middleware Use services of Open Database Connectivity (ODBC) Use Object Linking and Embedding Database (OLE DB) interface with Windows ODBC most common 11 Web-to-Database Middleware Connection Methods Native SQL access middleware Use services of Open Database Connectivity (ODBC) Use Object Linking and Embedding Database (OLE DB) interface with Windows ODBC most common Connecting from the web to the database via some middleware can use various access methods, or technologies. Some middleware uses SQL in its native format to access the database. Open Database Connectivity, or ODBC, is a Microsoft “defacto” standard, which is essentially a SQL API. It is the most common form of connecting an application to a data source. 11

ODBC to Access Databases 12 ODBC to Access Databases Figure 15.3 Many third party application development tools use ODBC as the way to access the database. Figure 15.3 12

Web-to-Database Middleware Uses ODBC to Access Databases 13 Web-to-Database Middleware Uses ODBC to Access Databases Figure 15.4 Here is a good illustration of how an application would use ODBC technology to interface the application with the relational database, and connect to the data source. Figure 15.4 13

Web Browser Located on the client computer End user Web interface Interprets HTML code received from Web server Presents page components in a standard way Client-side extensions Plug-ins Java and JavaScript ActiveX and VBScript 14 Web Browser Located on the client computer End user Web interface Interprets HTML code received from Web server Presents page components in a standard way Client-side extensions Plug-ins Java and JavaScript ActiveX and VBScript The web browser is essentially the “client” where the user interface runs. The browser interprets HTML code and presents it in a format that the user can read. There are “extensions” on the client-side, referred to as plug-ins, script, or controls, that allow enhancements at the presentation layer to the user. 14

The Web as a Stateless System Web server does not know status of any client at any given time Request-reply model of communication Browser concerned only with current page Data processing requires additional software Java, JavaScript, VBScript 15 The Web as a Stateless System Web server does not know status of any client at any given time Request-reply model of communication Browser concerned only with current page Data processing requires additional software Java, JavaScript, VBScript The web is considered to be “stateless”, meaning that it does not know the status of any client at any given time. Clients simply initiate “requests” that are processed by the server-side, and the a “reply” is sent back to the client. Browsers are the ultimate “thin client” in that they have minimal resources, are only concerned with presentation of the current page, and require additional technology to achieve any kind of processing. 15

Internet Database: Special Considerations Involve more than just database-enabled Web applications Issues important to corporate databases Data security Transaction management Client-side data validation Operational and management challenges Database applications development most affected by Internet 16 Internet Database: Special Considerations Involve more than just database-enabled Web applications Issues important to corporate databases Data security Transaction management Client-side data validation Operational and management challenges Database applications development most affected by Internet Some of the special considerations with Internet database design are data security, transaction management, client-side data validation, and some operational/management issues. Since the interface works differently than a standard client/server implementation, database engineers must work closely with network engineers to address certain issues of special concern to Internet database applications. 16

Supported Data Types Integrated data from multiple sources Word-processor documents Pictures Sounds Movies Methods for storing and extracting data objects Overhead created by storage Client browser support of object being accessed Size of database considering multimedia and other data 17 Supported Data Types Integrated data from multiple sources Word-processor documents Pictures Sounds Movies Methods for storing and extracting data objects Overhead created by storage Client browser support of object being accessed Size of database considering multimedia and other data The Internet database applications support a full range of data types across the Internet. Working with large files from multimedia data types generally has more issue with availability of bandwidth, than from any database management issues. 17

Data Security Web Server Level RMDBS Vendors Secure transactions using encryption TCP/IP protocol level Firewalls RMDBS Vendors Login authentication Restrict access to particular SQL commands Web-to-database middleware End user restrictions Designer created algorithms Must support e-commerce applications 18 Data Security Web Server Level Secure transactions using encryption TCP/IP protocol level Firewalls RMDBS Vendors Login authentication Restrict access to particular SQL commands Web-to-database middleware End user restrictions Designer created algorithms Must support e-commerce applications Data security is a big issue on the Internet. With the potential for data security to be violated many times higher because of the general access to the Internet, many ecommerce applications work with both database security and network security as an integrated policy of how to protect data coming across the Internet. 18

Transaction Management Concept is foreign to Web Dilemma created by request-reply model Web cannot maintain open line between client and database Recovery requires client maintain open communications Designers must ensure proper transaction management support at database server level 19 Transaction Management Concept is foreign to Web Dilemma created by request-reply model Web cannot maintain open line between client and database Recovery requires client maintain open communications Designers must ensure proper transaction management support at database server level Transaction management is a little different across the Internet because of the lack of a persistent connection between the database and the application. Transaction management must be supported at the database server level. 19

Denormalization Web forms Solutions Cannot use multiple data entry lines 1:M relationships problematic Solutions Web programming languages Java, JavaScript, VBScript 20 Denormalization Web forms Cannot use multiple data entry lines 1:M relationships problematic Solutions Web programming languages Java, JavaScript, VBScript Sometimes database applications must “denormalize” data to get associated data into one table so that web forms can be developed to access the data. Fortunately, there are solutions to these kinds of problems through the use of various web programming languages. 20