CGIandAJAX.ppt

CGI and AJAX CS-260 Dick Steflik CGI Common Gateway Interface A set of standards that define how information is exchanged between a web server and a ccustom script CGI Spec is maintained by NCSA (National Center for Supercomputing Applications A standard for external gateway programs to interface with information servers such as HTTP servers When running a python program as a CGI program sysin , sysout and syserr are redefined to : sysin: instead of coming from the keyboard is the incoming data stream from the tcpip socket (the remote host, the user’s browser). This will actually be handled via CGI Environment variables sysout: instead of printing to the screen prints to the tcpip outgoing data stream, to the user’s browser) Input Input for your CGI program will be handled by the HTTP server (Apache) and will be placed in a set of HTTP environment variables, and in a special data structure called FieldStorage. FieldStorage Methods: add_field(name,value clear() get(name, default) getfirst(name[,default]) getlist(name) has_key(name) Items() keys() What is AJAX Asynchronous Javascript And XML allows the updating of a web page without doing a page reload creates much nicer user experience AJAX is not really a technology by itself combination of Javascript, XML and some server-side scripting to create the XML server-side scripting could be done in PHP, .NET, Java Servlet or Java Server Page (JSP) General Technique Web Page Server-side Script requests server-side script to be run script run, XML created XML document returned info parsed from XML and used to update DOM by Javascript Sending a request for a URL xmlHttpRequest Object mozilla objXMLHttp=new XMLHttpRequest() IE objXMLHttp=new ActiveXObject(Microsoft.XMLHTTP) create the URL tell the browser the name of the function to handle the response send the url to the server example var url=servertime.php xmlHttp.onreadystatechange=stateChanged xmlHttp.open(GET,url,true) xmlHttp.send(null) The server-sid