web technologies and programming cse4461 - hypermedia and multimedia technology fanis tsandilas...
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web technologies and programming
cse4461 - hypermedia and multimedia technology
Fanis Tsandilas
April 3, 2007
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the HyperText Transfer Protocol
HTTP request(TCP stream)
web client - browserweb server
HTTP response(TCP stream)
TCP port: 80
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HTTP request
request line (GET, POST, HEAD methods)GET /path/to/file/index.html HTTP/1.0
header lines (info about request, user, etc.)
User-Agent: Mozilla 4.0 (X; I; Linux-2.0.35i586)Host: www.hypermedia-wiki.netAccept: text/html image/gif, image/jpegAuthorization: user fanis:mypassword
request body (content of a form, etc.)
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GET request
GET /cse4461/index.php?title=Main_Page HTTP/1.1 Accept: image/gif, image/x-xbitmap, image/jpeg,*/* Accept-Language: en-us Accept-Encoding: gzip, deflate User-Agent: Mozilla/4.0 (compatible; MSIE 5.01;
Windows NT) Host: www.hypermedia-wiki.net Connection: Keep-Alive
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GET request
GET /cse4461/index.php?title=Main_Page HTTP/1.1 Accept: image/gif, image/x-xbitmap, image/jpeg,*/* Accept-Language: en-us Accept-Encoding: gzip, deflate User-Agent: Mozilla/4.0 (compatible; MSIE 5.01;
Windows NT) Host: www.hypermedia-wiki.net Connection: Keep-Alive
passing parameters
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GET request
GET /cse4461/index.php?title=Main_Page HTTP/1.1 Accept: image/gif, image/x-xbitmap, image/jpeg,*/* Accept-Language: en-us Accept-Encoding: gzip, deflate User-Agent: Mozilla/4.0 (compatible; MSIE 5.01;
Windows NT) Host: www.hypermedia-wiki.net Connection: Keep-Alive
can keep TCP connection open to perform multiple requests(supported by newer browsers)
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forms and post requests
<form action="/search.php" method="post"> Country: <input name=“country” type=“text”> City: <input name=“city” type=“text”><input type=“submit”> </form>
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forms and post requests
POST /search.cgi HTTP/1.0 Host: www.example.com User-Agent: HTTPTool/1.0 Content-Type: application/x-www-form-urlencoded Content-Length: 26
country=Canada&city=Toronto+Ontario
<form action="/search.php" method="post"> Country: <input name=“country” type=“text”> City: <input name=“city” type=“text”><input type=“submit”> </form>
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HTTP response
HTTP/1.1 200 OK Date: Mon, 06 Dec 1999 20:54:26 GMT Server: Apache/1.3.6 (Unix) Last-Modified: Fri, 04 Oct 1996 14:06:11 GMT Content-language: en Connection: close Content-type: text/html Content-length: 1012
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01Transitional//EN">
<HTML> … </HTML>
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HTTP response
status code
header
responsebody
HTTP/1.1 200 OK Date: Mon, 06 Dec 1999 20:54:26 GMT Server: Apache/1.3.6 (Unix) Last-Modified: Fri, 04 Oct 1996 14:06:11 GMT Content-language: en Connection: close Content-type: text/html Content-length: 1012
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01Transitional//EN">
<HTML> … </HTML>
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status codes
200 OK 301 Moved Permanently
400 Bad Request 401 Unauthorized 403 Forbidden 404 Not Found 500 Internal Server Error …
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authorization
types : HTTP Basic, HTTP Digest
GET /private/index.html HTTP/1.0Host: www.example.comAuthorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==
authorization key
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limitations of HTTP
no build-in security mechanisms
stateless - no support for session management
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session management
techniques URL rewriting hidden form fields cookies SSL sessions
client server
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cookies
extension of HTTP - servers can store data on the client limited size, number client may disable them
GET /index.html HTTP/1.1Host: www.example.com
HTTP/1.1 200 OKContent-type: text/htmlSet-Cookie: name=value
(content of page)
GET /pictures.htmlHost: www.example.comCookie: name=valueAccept: */*
client server
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cookie attributes
Set-Cookie: name=value; expires=date; path=/; domain= example.org
Example
Set-Cookie: RMID=732423sdfs73242; expires=Fri, 31-Dec-2010 23:59:59 GMT; path=/; domain= example.org
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SSL
SSL: Secure Sockets Layer TLS: Transport Layer Security
(newer)
runs between application layer (e.g., HTTP, FTP, SMTP) and TCP HTTP: accessed by https://….
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server programming
PHP
ASP (Active Server Pages) Microsoft’s product
Servlets and JSP (JavaServer Pages)
Perl
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Java Servlet API
Java API for server programming
main classes HttpServlet HttpServletRequest HttpServletResponse HttpSession
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example: Java servlet
import java.io.*;import javax.servlet.*;import javax.servlet.http.*;
public class Simple extends HttpServlet { public void doGet(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");PrintWriter out = response.getWriter();
out.println("<HTML><BODY>" + “<h1> Parameters </h1>”+ “<UL>”+ “<LI> Parameter 1: ” + request.getParameter(“param1”)+“\n”;+ “<LI> Parameter 2: ” + request.getParameter(“param2”); + “<UL>” + “</BODY></HTML>");
}}
SimpleServlet.java
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sessions in servlets
one HttpSession object for each session obtained by getSession in
HttpServletRequest object
session state setAttribute(“name”, value) getAttribute(“name”)
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JSP
servlets require Java and sophisticated programming
In JSP, web applications are active pages HTML with snippets of code JSP pages are translated into
servlets
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example: JSP
<%! int add(String x, String y){ return Integer.parseInt(x) + Integer.parseInt(y);
}%>
<html><head><title>Addition</title></hrad><body>
The sum of <%= request.getParameter(“x”) %>and <%= request.getParameter(“y”) %>is <%= add(request.getParameter(“x”),
request.getParameter(“y”)) %></body>
</html>
example.jsp
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php
open source, mainly used for server-side scripting
example: handling a simple form
This is what you submitted:<p><b>Country:</b> <?php echo $_REQUEST[”country"]; ?> <br><b>City:</b> <?php echo $_REQUEST[”city"]; ?>
example.php
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SOAP (Simple Object Access Protocol)
communication between remote applications through HTTP
platform/language independent
XML syntax
simple and extensible
will be developed as W3C standard
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example: SOAP
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
<soap:Body> <getProductDetails xmlns="http://warehouse.example.com/ws">
<productID>235346</productID></getProductDetails>
</soap:Body> </soap:Envelope>
message requesting details for product with ID = 235346
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example: SOAP
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
<soap:Body> <getProductDetailsResponse
xmlns="http://warehouse.example.com/ws"> <getProductDetailsResult>
<productID>235346</productID><price currency=“CAD”>25.90</price><inStock>true</inStock>
</getProductDetailsResult></getProductDetailsResponse>
</soap:Body> </soap:Envelope>
message giving details for requested product
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SOAP = XML + HTTP
POST /index.html HTTP/1.1Host: www.example.comContent-Type: application/soap+xml; charset=utf-8Content-Length: 3012
…xml syntax representing a SOAP message…
HTTP/1.1 200 OKContent-Type: application/soap+xml; charset=utf-8Content-Length: 1020
…xml syntax representing another SOAP message…
client server
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AJAX
AJAX = Asynchronous JavaScript And XML
direct communication of JavaScript with the server through JavaScript XMLHttpRequest
object (Firefox, Safari) or ActiveXObject (IE)
no need to reload a page for every request for a change
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example: AJAX
<html><body><script type=“text/javascript”>function updateFunction(){ var xmlHttp; try{ xmlHttp = new XMLHttpRequest(); } //Firefox, Opera 8.0+, Safari catch(e) { alert(“browser not supported”); return false;}
// when the request has been completed the time field of // myForm will be updated by the response value xmlHttp.onreadystatechange = function(){
if(xmlHttp.readyState == 4) document.myForm.time.value = xmlHttp.responseText;
} // preparing and sending the request to the server // it will be served by time.php xmlHttp.open(“GET”, “time.php”, true); xmlHttp.send(null);}</script>
…</html>
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conclusions
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