Tutoring the 21st Century
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Transcript Tutoring the 21st Century
Tutoring the 21st Century
Tutoring.NET A communication portal for e-learning
brought to you by: Markus Beier, Caroline Daniel, Daniel Dudaszek,
Marc Hermann, Stéphanie Lecat, Daniel Toeller
Tutoring the 21st Century
Goals :
• Contact point for students and tutors
• Give students the opportunity to contact
their tutors independent of location and
time.
• Tutors shall be able to decide when,
where and how they can be reached.
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How we achieved this :
• Web portal as a meeting point
• SIP enables the new ways of
communication
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Functionality of the web site
1.General Features
2.Student
3.Teacher
4. Admin
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Functionality of the web site – Generality
•
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Register (see student and teacher part)
Log-in
Send an email
Make a call (SIP or Netmeeting)
Log-out
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Functionality of the web site - Student
• Register yourself
• Messages from the teachers
• Courses you can join or quit, courses you are
already in
• Students work group
• Students in your courses
• Teachers of your courses
• Edit your profile
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Functionality of the web site - Teacher
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Ask the administrator to register
Manage your messages
Courses you are in charge of, deletion, addition
Teacher work group
Students in your courses
Edit your profile
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Functionality of the web site - Admin
• Create a teacher account
• See the list of all the work group (student and
teacher)
• See the list of all the students
• See the list of all the teachers
• See the list of all the courses
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Database
1. MySQL
2. Our database
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Database – Advantage of MySQL
• MySQL is a robust and performing SQL server
• MySQL easily work with scripts language as PHP
• PhpMyAdmin is an easy to learn interface to
manage MySQL database
• Not perfect but...
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Our Database – schema
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Dynamic Web Pages
Web page created in response to the request of a user,
whose contents is variable
Collecting and sending to the Web server the
information entered by the user in a form
Transmission of this data to a script or an application
for their processing
Querying of a Database
Returning the result to the user in a HTML page
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Use of PHP
What is php
It is a script language
Embedded in a normal HTML page
Executed by the Web server
It will enable us to manage and use our MySQL
database
And using data entered by the visitors
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How a PHP program looks like
the tags <?php and
?> represent the beginning and
the end of a PHP program .
Example :
<html>
<head><title>Example</title></head>
<body>
<H1>
<?php
printf(“ the sum equals : $a + $b
“,2,3);
?>
</H1>
</body>
</html>
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Result
At the end of its execution the part which goes from
<?php to ?> is removed or replaced by the result of the
program. For this example the result we have is :
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The advantage of the use of PHP
The PHP Code is executed only by the server
Compatible with all kind of browsers
Free software and availability of the source code
Simplicity of writing of scripts
Simplicity of interaction with databases
Integration within many Web servers (Apache,
Microsoft IIS, ...)
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Personalised webpages
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– Functionalities of Tutoring.net site
require personalised webpages
– Example: two students which connect to
the same page
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– main problem: stateless HTTP protocol
request response principle
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• Solution
– Session:
• defines an state between server and client
• problem here: how to identify a unique user
• generate Session ID
– possibilities to pass the Session ID:
• use the GET Parameter
• store it in a cookie
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• Session Management:
– At the server side:
• Store Informations about each active
Session
• Database, shared memory,filesystem
– Sessions properties:
• store variables
• have a lifetime
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• Authentication:
– allow webserver to identify client
• Methods to implement Authentication
– Basic Authentication
– Session Based Authentication
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Basic Authentication vs. Session Based Authentication
Basic Authentication
Session Based Authentication
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Basic Authentication vs. Session Based Authentication
+
Basic Authentication
easy
implementation
Session Based
Authentication
automatic logout
possible
web design
possible
no automatically
logout possible
no web design
possible
the user might be
lead to uncertainty
necessity to
implementate all
Session
functionalities
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• PHPLIB
• overview of selective Features:
Session Management
User Management
Authentication
Database Access
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• Example Authentication:
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Access to page which requires authentication
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Login form is shown first
which is totally independent
from the protected site
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If login is valid the requested site is shown
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SIP
Session Initiation Protocol
How to initiate a session with SIP
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1. Purpose of the protocol
2. Basics
3. Example
SIP – Session Initiation Protocol
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• Mr. Blue wants to call Mr. White via VoIP
Questions:
– Which IP has Mr. White
– which type of session shall be initiated
– which parameters has the session
Solution: SIP
SIP – Session Initiation Protocol
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• textbased protocol, uses UDP (TCP)
• closely related to HTTP (same response
codes, authentication schemes)
• clear separation: signalling of the session –
type of session (e.g. telephone call, game)
• uses the proxy principle
• control via 6 methods: REGISTER, INVITE,
ACK, BYE, OPTIONS, CANCEL
SIP – Session Initiation Protocol
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Sample SIP Message
INVITE sip:[email protected] SIP/2.0
Via: SIP/2.0/UDP 134.155.12.22:5060
From: sip:[email protected]
To: sip:[email protected]
Contact: sip:[email protected]
Call-ID: [email protected]
CSeq: 27246067 INVITE
Content-Length: 175
Content-Type: application/sdp
User-Agent: eStara SoftPHONE
v=0
o=eStara 27246067 27246067 IN IP4 134.155.12.22
s=eStara
c=IN IP4 134.155.12.22
t=0 0
m=audio 8000 RTP/AVP 0 101
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15
SIP – Session Initiation Protocol
Header
Contains the
signalling information
Body
Contains the
description of the
session
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Example call
[email protected]
=
12.12.12.12
Mr. White turns
on the phone
REGISTER
SIP Proxy
FROM: [email protected]
Contact:12.12.12.12
SIP – Session Initiation Protocol
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Example call
[email protected]
=
12.12.12.12
Mr. White turns
on the phone
200 OK
SIP Proxy
SIP – Session Initiation Protocol
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Example call
[email protected]
=
12.12.12.12
Mr. Blue
places a call
INVITE
FROM: [email protected]
TO: [email protected]
SIP Proxy
<Session Data>
SIP – Session Initiation Protocol
Mr. White
waits for calls
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Example call
[email protected]
=
12.12.12.12
Mr. Blue
places a call
100 Trying
Mr. White
waits for calls
INVITE
SIP Proxy
FROM: [email protected]
TO: [email protected]
<Session Data>
SIP – Session Initiation Protocol
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Example call
[email protected]
=
12.12.12.12
Mr. Blue‘s
phone rings
180 Ringing
Mr. White‘s
phone rings
180 Ringing
SIP Proxy
SIP – Session Initiation Protocol
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Example call
[email protected]
=
12.12.12.12
Mr. Blue‘s
phone rings
200 OK
Mr. White
accepts
200 OK
SIP Proxy
SIP – Session Initiation Protocol
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Example call
[email protected]
=
12.12.12.12
Mr. Blue is
on line
ACK
Mr. White is
on line
ACK
SIP Proxy
RTP audio streams
SIP – Session Initiation Protocol
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Example call
[email protected]
=
12.12.12.12
Mr. Blue is
off line
BYE
Mr. White
ends the call
BYE
SIP Proxy
SIP – Session Initiation Protocol
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Example call
[email protected]
=
12.12.12.12
Mr. Blue is
off line
ACK
Mr. White is
off line
ACK
SIP Proxy
Call Duration 6 minutes: Fee 6€
SIP – Session Initiation Protocol
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Call Logic
Programming Sip:
• CPL(Call Processing Language)
• SIP CGI (Common Gateway Interface)
• SIP Servlets
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What is CPL?
• an XML-based scripting language for
describing and controlling call services
• a list of condition/action pairs
– Example:
„If someone is calling during the presentation, redirect the
call to the voicemail server.“
„Redirect my friends to my cell phone, anyone else to my
office.“
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CPL Scripts can be based on:
• Caller/Callee
– Address
– Name
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Call subject
Caller's organization
Call Priority
Time periods
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Where does CPL run?
A CPL script runs in a signalling
server, and controls actions for the set up
of a particular call
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CPL Script example
<?xml version="1.0" ?>
<!DOCTYPE cpl PUBLIC "-//IETF//DTD RFCxxxx CPL
1.0//EN" "cpl.dtd">
<cpl>
<incoming>
<location url="sip:[email protected]">
<redirect />
</location>
</incoming>
</cpl>
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CPL scripts can be created
in 2 ways
1. Advanced users can do it by hand
2. With GUI based tools (Indigo CPL Editor)
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Sip CGI
• Similar to Web-CGI
• Language-independent (Perl,C,...)
• Security problem:
– CGI programs are unlimited in their power
buggy scripts may affect server
only for admin
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Sip Servlets
• Compromise between security and
power
Security provided by Java Sandbox
Still powerful
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Call processing overview
Generality
Security
CGI
highest
lowest
Servlets
medium
medium
CPL
lowest
highest
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SIP User Agents
Functionality and Restrictions
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Overview
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What is a User Agent ?
How does a User Agent work ?
Several used and tested UAs
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eStara Softphone
Microsoft Netmeeting
Pingtel XPressa
History Client
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Overview
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•
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What is a User Agent ?
How does a User Agent work ?
Several used and tested UAs
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eStara Softphone
Microsoft Netmeeting
Pingtel XPressa
History Client
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What is a User Agent ?
•A Hard – or Software based Phone to call someone over the Internet
•Two „implementations“ :
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A „real“ Telephone (Hardphone) with internet-software running
•
A so called „Softphone“, a special software that uses Internet
communication protocols to run
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Overview
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What is a User Agent ?
How does a User Agent work ?
Several used and tested UAs
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eStara Softphone
Microsoft Netmeeting
Pingtel XPressa
History Client
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RTP
SIP
SIP
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Overview
•
•
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What is a User Agent ?
How does a User Agent work ?
Several used and tested UAs
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eStara Softphone
Microsoft Netmeeting
Pingtel XPressa
History Client
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eStara Softphone
•SIP enabled
•Three different Lines for different
simultaneous calls
•Forwarding calls possible
•Also possible to run as an applet for
customer services
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eStara Softphone
•The only UA, which is launchable
directly from the webpage
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eStara Softphone
•The only UA, which is launchable
directly from the webpage
•SIP Message Log for detailed look at
the SIP Messages
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Overview
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What is a User Agent ?
How does a User Agent work ?
Several used and tested UAs
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eStara Softphone
Microsoft Netmeeting
Pingtel XPressa
History Client
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Microsoft Netmeeting - Features
•H.323 Phone
•Supports :
Whiteboards
Chat
Videocall
Sharing Programs / Desktop
File Transfer
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Microsoft Netmeeting - Features
•The only UA which is integrated
directly into the webpage via an
Active-X-Control
•Embedded into the HTML by the
<object> tag
•Many possibilities :
•Full UI
•Only Parts of the UI
•Buttons to control the call
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Microsoft Netmeeting - Calling
If Netmeeting is integrated via
Active-X into the webpage,
the call is directly made
Hard-coded IP-Adress to reach
a specified computer
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Overview
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What is a User Agent ?
How does a User Agent work ?
Several used and tested UAs
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eStara Softphone
Microsoft Netmeeting
Pingtel XPressa
History Client
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The Hardphone
Pingtel XPressa
•Runs Java and SIP
•Multiple simultaneous calls
•World´s first Java VoIP-Phone
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The Softphone
Instant Xpressa
•Emulation of the Pingtel XPressa
•Xdk to develop Java Apps
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Overview
•
•
•
What is a User Agent ?
How does a User Agent work ?
Several used and tested UAs
•
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eStara Softphone
Microsoft Netmeeting
Pingtel XPressa
History Client
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• HistoryClient
•Prototype - Software for the tutor
•Shows Notes that were made during earlier
sessions with the caller to make it easier to
keep track of the problems.
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DEMONSTRATION
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Assessment
• On a technical level
– SIP, protocols for videoconferences, PHP
• On a personal level
– Intercultural work, dealing with misunderstandings
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Ideas for the future
• Improve billing function
• Make a SIP call to a telephone network
• Getting CPL scripts to work
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Thank you for your
attention
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?