Lecture 3 Web Technologies Part 2 1 Web
Lecture 3 Web Technologies Part 2 1
Web Technologies l l l HTML XHTML CSS XML Java. Script VBSCRIPT DOM DHTML AJAX E 4 X WMLScript SQL l l l ASP ADO PHP CGI PERL. NET SMIL SVG FLASH Java applets Java servlets Java Server page 2
What is SQL? l l l l SQL stands for Structured Query Language SQL allows you to access a database SQL can execute queries against a database SQL can retrieve data from a database SQL can insert new records in a database SQL can delete records from a database SQL can update records in a database SQL is easy to learn 3
SQL Data Manipulation Language (DML) l l SQL (Structured Query Language) is a syntax for executing queries. But the SQL language also includes a syntax to update, insert, and delete records. These query and update commands together form the Data Manipulation Language (DML) part of SQL: • • SELECT - extracts data from a database table UPDATE - updates data in a database table DELETE - deletes data from a database table INSERT INTO - inserts new data into a database table 4
SQL Data Definition Language (DDL) l l The Data Definition Language (DDL) part of SQL permits database tables to be created or deleted. We can also define indexes (keys), specify links between tables, and impose constraints between database tables. The most important DDL statements in SQL are: • • • CREATE TABLE - creates a new database table ALTER TABLE - alters (changes) a database table DROP TABLE - deletes a database table CREATE INDEX - creates an index (search key) DROP INDEX - deletes an index 5
SQL on the WEB l l l Many web applications require database at the back side. We can use SQL for database activities. We use SQL together with other technologies. 6
SQL Example with ASP <html> <head> <title>My First ASP Page</title> </head> <body bgcolor="white" text="black"> <% Dim ado. Con Dim rs. Guestbook Dim str. SQL 'Create an ADO connection object Set ado. Con = Server. Create. Object("ADODB. Connection ") 'Set an active connection to the Connection object using a DSN-less connection ado. Con. Open "Provider=Microsoft. Jet. OLEDB. 4. 0; Data Source=" & Server. Map. Path("mydb. mdb ") 'Create an ADO recordset object Set rs. Guestbook = Server. Create. Object("ADODB. Recordset ") 'Initialise the str. SQL variable with an SQL statement to query the database str. SQL = "SELECT Friends. Name, Friends. link FROM Friends; " 'Open the recordset with the SQL query rs. Guestbook. Open str. SQL, ado. Con 7
SQL Example with ASP 'Loop through the recordset Do While not rs. Guestbook. EOF 'Write the HTML to display the current record in the recordset Response. Write (" ") Response. Write (rs. Guestbook("Name")) Response. Write (" ") Response. Write (rs. Guestbook("link")) Response. Write (" ") Response. Write("Murat Koyuncu") 'Move to the next record in the recordset rs. Guestbook. Move. Next Loop 'Reset server objects rs. Guestbook. Close Set rs. Guestbook = Nothing Set ado. Con = Nothing %> </body> </html> 8
What is ASP? l l l ASP stands for Active Server Pages. ASP is a program that runs inside IIS stands for Internet Information Services. IIS comes as a free component with Windows Servers. PWS is a smaller - but fully functional version of IIS (for Windows 95/98). 9
ASP Compatibility l l l ASP is a Microsoft Technology. To run IIS you must have Windows NT 4. 0 or later. To run PWS you must have Windows 95 or later. 10
What is an ASP File? l l An ASP file is just the same as an HTML file. An ASP file can contain text, HTML, XML, and scripts. Scripts in an ASP file are executed on the server. An ASP file has the file extension ". asp“. 11
How Does ASP Differ from HTML? l l When a browser requests an HTML file, the server returns the file. When a browser requests an ASP file, IIS passes the request to the ASP engine. The ASP engine reads the ASP file, line by line, and executes the scripts in the file. Finally, the ASP file is returned to the browser as plain HTML. 12
What can ASP do for you? Dynamically edit, change or add any content of a Web page. l Respond to user queries or data submitted from HTML forms. l Access any data or databases and return the results to a browser. l Customize a Web page to make it more useful for individual users. l The advantages of using ASP instead of CGI and Perl, are those of simplicity and speed. l Provide security since your ASP code can not be viewed from the browser. l Clever ASP programming can minimize the network traffic. Important: Because the scripts are executed on the server, the browser that displays the ASP file does not need to support scripting at all! l 13
ASP Example <html> <body> <% response. write("Hello World!") %> </body> </html> 14
ASP Example-Code <html> <body> <% response. write(Format. Date. Time(date(), vbgeneraldate)) response. write(" ") response. write(Format. Date. Time(date(), vblongdate)) response. write(" ") response. write(Format. Date. Time(date(), vbshortdate)) response. write(" ") response. write(Format. Date. Time(now(), vblongtime)) response. write(" ") response. write(Format. Date. Time(now(), vbshorttime)) %> <p> Syntax for Format. Date. Time: Format. Date. Time(date, namedformat). </p> </body> </html> 15
ASP Example-Output 12/10/2007 Monday, December 10, 2007 12/10/2007 9: 16: 58 AM 09: 16 Syntax for Format. Date. Time: Format. Date. Time(date, namedformat). 16
What is ADO? l l l ADO is a Microsoft technology. ADO stands for Active. X Data Objects. ADO is a Microsoft Active-X component. ADO is automatically installed with Microsoft IIS. ADO is a programming interface to access data in a database. 17
Accessing a Database from an ASP Page The common way to access a database from inside an ASP page is to: • • Create an ADO connection to a database. Open the database connection. Create an ADO recordset. Open the recordset. Extract the data you need from the recordset. Close the connection. 18
Create a Database Connection <% set conn=Server. Create. Object ("ADODB. Connection") conn. Provider="Microsoft. Jet. OLEDB. 4. 0" conn. Open "c: /webdata/northwind. mdb" %> 19
An ODBC Connection to an MS Access Database Here is how to create a connection to a MS Access Database: l Open the ODBC icon in your Control Panel. l Choose the System DSN tab. l Click on Add in the System DSN tab. l Select the Microsoft Access Driver. Click Finish. l In the next screen, click Select to locate the database. l Give the database a Data Source Name (DSN). l Click OK. 20
An ODBC Connection to an MS Access Database <% set conn=Server. Create. Object ("ADODB. Connection") conn. Open "northwind" %> Name defined in ODBC 21
Create an ADO Table Recordset <% Set conn=Server. Create. Object ("ADODB. Connection") conn. Provider="Microsoft. Jet. OLEDB. 4. 0" conn. Open "c: /webdata/northwind. mdb“ Set rs=Server. Create. Object ("ADODB. recordset") rs. Open "Customers", conn %> 22
Create an ADO SQL Recordset <% Set conn=Server. Create. Object ("ADODB. Connection") conn. Provider="Microsoft. Jet. OLEDB. 4. 0“ conn. Open "c: /webdata/northwind. mdb“ set rs=Server. Create. Object ("ADODB. recordset") rs. Open "Select * from Customers", conn %> 23
Extract Data from the Recordset <%. . . for each x in rs. fields response. write(x. name) response. write(" = ") response. write(x. value) next. . %> 24
ADO Example <html> <body> <% set conn=Server. Create. Object("ADODB. Connection") conn. Provider="Microsoft. Jet. OLEDB. 4. 0" conn. Open "c: /webdata/northwind. mdb“ set rs = Server. Create. Object("ADODB. recordset") rs. Open "SELECT * FROM Customers", conn do until rs. EOF for each x in rs. Fields Response. Write(x. name) Response. Write(" = ") Response. Write(x. value & " ") next Response. Write(" ") rs. Move. Next loop rs. close conn. close %> </body> </html> 25
What is PHP? l PHP stands for PHP: Hypertext Preprocessor. l PHP is a server-side scripting language, like ASP. l PHP scripts are executed on the server. l PHP supports many databases (My. SQL, Informix, Oracle, Sybase, Solid, Postgre. SQL, Generic ODBC, etc. ) l PHP is an open source software (OSS). l PHP is free to download and use. 26
What is a PHP File? l l l PHP files may contain text, HTML tags and scripts. PHP files are returned to the browser as plain HTML. PHP files have a file extension of ". php", ". php 3", or ". phtml" 27
Why PHP? l l PHP runs on different platforms (Windows, Linux, Unix, etc. ). PHP is compatible with almost all servers used today (Apache, IIS, etc. ). PHP is FREE to download from the official PHP resource: www. php. net. PHP is easy to learn and runs efficiently on the server side. 28
A free web server platform l l l Install an Apache server on a Windows or Linux machine. Install PHP on a Windows or Linux machine. Install My. SQL on a Windows or Linux machine. 29
What do PHP code look like? l l PHP is a rather simple language. Much of its syntax is borrowed from C except for dealing with the types of variables. You don't need to think of the types of variables at all - you just work with their values, not their types. And you don't have to declare variables before you use them. 30
A simple PHP example <html> <body> <? php echo "Hello World"; ? > </body> </html> 31
PHP Examples <html> <body> <? php $d=date("D"); if ($d=="Fri") echo "Have a nice weekend!"; else echo "Have a nice day!"; ? > </body> </html> <body> <? php for ($i=1; $i<=5; $i++) { echo "Hello World!<br />"; } ? > </body> </html> 32
PHP Database Example <? php $con = mysql_connect("localhost", "peter", "abc 123"); if (!$con) { die('Could not connect: '. mysql_error()); } mysql_select_db("my_db", $con); $result = mysql_query("SELECT * FROM person"); while($row = mysql_fetch_array($result)) { echo $row['First. Name']. " ". $row['Last. Name']; echo " "; } mysql_close($con); ? > 33
PHP ODBC Connection <html> <body> <? php $conn=odbc_connect('northwind', ''); if (!$conn) {exit("Connection Failed: ". $conn); } $sql="SELECT * FROM customers"; $rs=odbc_exec($conn, $sql); if (!$rs) {exit("Error in SQL"); } echo "<table><tr>"; echo "<th>Companyname</th>"; echo "<th>Contactname</th></tr>"; while (odbc_fetch_row($rs)) { $compname=odbc_result($rs, "Company. Name"); $conname=odbc_result($rs, "Contact. Name"); echo "<tr><td>$compname</td>"; echo "<td>$conname</td></tr>"; } odbc_close($conn); echo "</table>"; ? > </body> </html> 34
What is CGI? l l l The Common Gateway Interface (CGI) is a standard for interfacing external applications with information servers, such as HTTP or Web servers. A plain HTML document that the Web daemon retrieves is static, which means it exists in a constant state: a text file that doesn't change. A CGI program, on the other hand, is executed in real-time, so that it can output dynamic information. 35
What is CGI? l l l For example, let's say that you wanted to "hook up" your Unix database to the World Wide Web, to allow people from all over the world to query it. Basically, you need to create a CGI program that the Web daemon will execute to transmit information to the database engine, and receive the results back again and display them to the client. This is an example of a gateway, and this is where CGI, currently version 1. 1, got its origins. 36
What is CGI? l A CGI program can be written in any language that allows it to be executed on the system, such as: • • C/C++ Fortran PERL TCL Any Unix shell Visual Basic Apple. Script 37
What is MS. NET l . NET is Microsoft's new Internet and Web strategy. l . NET is NOT a new operating system. l . NET is a new Internet and Web based infrastructure. l . NET delivers software as Web Services. l . NET is a framework for universal services. l . NET is a server centric computing model. l . NET will run in any browser on any platform. l . NET is based on the newest Web standards. 38
. NET Internet Standards l l HTTP, the communication protocol between Internet Applications. XML, the format for exchanging data between Internet Applications. SOAP, the standard format for requesting Web Services. UDDI, the standard to search and discover Web Services. 39
. NET Framework l l The. NET Framework is the infrastructure for the new Microsoft. NET Platform. The. NET Framework contains common class libraries - like ADO. NET, ASP. NET and Windows Forms. The. NET Framework is language neutral. Currently it supports C++, C#, Visual Basic, JScript (The Microsoft version of Java. Script) and COBOL. The new Visual Studio. NET is a common development environment for the new. NET Framework. 40
. NET Framework 41
. NET Building Blocks l l l Web Services: Web Services provide data and services to other applications (HTTP, HTML, XML, and SOAP). Internet Directory Services: . NET supports a new kind of directory services that can answer XML based questions about Internet Services, far more exactly than search engines and yellow pages. These services are built on the UDDI standard. There also some others… 42
. NET Software l l l Windows. NET: Windows 2000 and Windows XP ASP. NET Visual Studio. NET Visual Basic. NET SQL Server 2000 Internet Information Services 6. 0 43
XML Based Web Protocols l l l SOAP: SOAP (Simple Object Access Protocol) is a lightweight platform and language neutral communication protocol that allows programs to communicate via standard Internet HTTP. SOAP is standardized by the W 3 C. WSDL: WSDL (Web Services Description Language) is an XML-based language used to define web services and to describe how to access them. WSDL is a suggestion by Ariba, IBM and Microsoft for describing services for the W 3 C XML Activity on XML Protocols. UDDI: UDDI (Universal Description, Discovery and Integration) is a directory service where businesses can register and search for web services. UDDI is a public registry, where one can publish and inquire about web services. 44
Web service 45
Java Applet? l What is Java applet? l What is Java servlet? l What is Java. Server Pages? l What is Java Web Start? 46
Java Applet l l An applet is a software component that runs in the context of another program, for example a web browser. A Java applet is an applet delivered in the form of Java bytecode. Java applets can run in a Web browser using a Java Virtual Machine (JVM), or in Sun's Applet. Viewer, a stand-alone tool for testing applets. 47
Java Applet l l l Java applets are usually written in the Java programming language but they can also be written in other languages that compile to Java bytecode. Applets are used to provide interactive features to web applications that cannot be provided by HTML. Since Java's bytecode is platform independent, Java applets can be executed by browsers for many platforms, including Windows, Unix, Mac OS and Linux. 48
Java bytecode l l l Java bytecode is the form of instructions that the Java virtual machine executes. Each bytecode instruction is one byte in length. Code: • • • 0: iconst_2 1: istore_1 2: iload_1 3: sipush 1000 6: if_icmpge 44 9: iconst_2 10: istore_2 11: iload_2 12: iload_1 41: goto 2 44: return 49
What Is a Servlet? l Web server response can be static or dynamic • • l Static: HTML document is retrieved from the file system and returned to the client Dynamic: HTML document is generated by a program in response to an HTTP request Java servlets are one technology for producing dynamic server responses • Servlet is a class instantiated by the server to produce a dynamic response 50
Servlet Overview 51
Servlet Example 52
Servlet Example 53
Servlets vs. Java Applications l Servlets do not have a main() • • l Entry point to servlet code is via call to a method (do. Get() in the example) Servlet interaction with end user is indirect via request/response object APIs • l The main() is in the server Actual HTTP request/response processing is handled by the server Primary servlet output is typically HTML 54
Running Servlets Simple way to run a servlet: 1. Compile servlet (make sure that JWSDP libraries are on path) 2. Copy. class file to shared/classes directory 3. (Re)start the Tomcat web server 4. If the class is named Servlet. Hello, browse to http: //localhost: 8080/servlet/Servlet. Hello 55
What is JSP? l l Short for Java Server Page. A server-side technology. Java Server Pages are an extension to the Java servlet technology that was developed by Sun. JSPs have dynamic scripting capability that works in tandem with HTML code. 56
What is JSP? l l The JSP syntax adds additional XML-like tags, called JSP actions, to be used to invoke built-in functionality. A JSP compiler may generate a servlet in Java code that is then compiled by the Java compiler, or it may generate byte code for the servlet directly. Compilation occurs the first time the application is run. A JSP Compiler is triggered by the. jsp file name extension in a URL. 57
JSP Example <%@ page error. Page="myerror. jsp" %> <%@ page import="com. foo. bar" %> <html> <head> <%! int server. Instance. Variable = 1; %>. . . <% int local. Stack. Based. Variable = 1; %> <table> <tr> <td><%= to. String. Or. Blank( "expanded inline data " + 1 ) %></td> </tr>. . . 58
JSP vs. Pure Servlets. l l l JSP doesn't give you anything that you couldn't in principle do with a servlet. But it is more convenient to write (and to modify!). By separating the look from the content you can put different people on different tasks: your Web page design experts can build the HTML, leaving places for your servlet programmers to insert the dynamic content. 59
JSP vs ASP l l It was originally created as an alternative to Microsoft's ASPs (Active Server Pages). Recently, however, Microsoft has countered JSP technology with its own ASP. NET, part of the. NET initiative. 60
JSP vs. Active Server Pages (ASP). l ASP is a similar technology from Microsoft. l The advantages of JSP are twofold. • • First, the dynamic part is written in Java, not Visual Basic or other MS-specific language, so it is more powerful and easier to use. Second, it is portable to other operating systems and non-Microsoft Web servers. 61
JSP vs. Java. Script. l l l Java. Script can generate HTML dynamically on the client. This is a useful capability, but only handles situations where the dynamic information is based on the client's environment. Since it runs on the client, Java. Script can't access server-side resources like databases, catalogs, pricing information, and the like. 62
What is Java Web Start? l l l Sun’s tool for installing Java applications and updates. It can also distribute Applets. They automatically install and hook themselves up to the Java runtime. All you have to do is click an icon with your browser to use them. Java Web Start makes it easy for users to install Java apps once they have a web start enabled browser, or the web start app installed. 63
What is Java Web Start? l l Java Web Start is a framework developed by Sun Microsystems which allows application software for the Java Platform to be started directly from the Internet using a web browser. Unlike Java applets, Web Start applications do not run inside the browser. One chief advantage of Web Start over applets is that they overcome many compatibility problems with browsers' Java plugins and different JVM versions. On the other hand, Web Start programs cannot communicate with the browser as easily as applets. 64
End of Lecture 3 65
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