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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B6. Istanbul 2004 
  
The more interactivity is needed, the more inevitable is the 
use of a program language. Java provides the most flexible 
solution and allows web-applications based on applets. 
Applets are loaded together with the web page from the 
server and are executed in the client's virtual machine. 
If it is necessary to compose a website in dependence of a 
user input, an interface has to be available, which allow the 
web-server to call external programs, which generate HTML 
code and send it back to the client. 
In this case the Java Server Pages (JSPs) concept is 
appropriate, which allows a separation of content and 
visualization. On the server, JSPs are compiled on first call 
and a servlet is generated. A so called container for servlet 
administration has to be implemented. This task is managed 
by the reference implementation Tomcat (see Figure 2). 
    
T 
send to em LES Lan 
FA ; T x Processing, 
Me 
HTTP-recuest get back | VM of | database 
de se { I j 
A MA — MQSEIVET SS BODeSS 
e" e 
HTTP-response ; arena iN 
DCT SSA SRE 
=k start servlets à 
webserver (e.g, tomcat) — compile 25Ps 
Figure 2. JSP technology 
4.2 User Management 
As already mentioned, it is necessary to introduce a user 
management for adapting the training course to the learners’ 
knowledge. All information about user activities is stored in a 
user database. 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
user 
log ID 5 test log 
ID Kin name Il ID 
user ID password user ID 
date date chapter ID 
time time date 
state time 
question log chapter ID answered questions 
ID assessment 
user ID result log 
question ID ID 
date — user ID 
time chapter ID 
answer flag date 
state time 
  
  
  
  
  
  
Figure 3. Tables needed for user administration 
After successful registration and authentication a new user 
and several other tables are created, recording all information 
needed for obtaining the user state and assessing the students' 
capability (see Figure 3). 
141 
Each user record contains fields for user name and password, 
date and fime of first registration. The s/ate and the 
chapter id field gives information about the chapter which 
has recently been worked on. These keys allow the user to 
continue working at the point he had left the course before. In 
the assessment column the performance ratio of the student is 
stored. Information in the result log and question log tables 
is needed for the calculation of this assessment value. More 
details are given in chapter 4.4. 
4.3 Administration of Chapters 
The modular approach of the learning system requires 
administration of course content, which is structured in 
hierarchical chapters as seen in Figure 1. Storing 
informations about the modules in a database allows 
separation of context from the sequence of the tutorial. Once 
the learning path is defined, linking the modules and 
generation of the table of contents are processed 
automatically. Later changes in course and structure will be 
assisted by a seperate management tool, which will be 
developed in the near future. 
    
   
  
     
   
   
metadata 
  
    
   
   
ter ID 
author 
keywords 
date 
   
    
   
    
   
      
name 
order 
directo 
r af 
    
estions 
    
er 
name lon 
content 
    
  
   
    
    
  
er ID 
directo 
arder 
   
   
Figure 4. Data base tables for chapters 
The structure of database tables used for chapter organization 
is seen in Figure 4. An individual /D is assigned to each 
chapter automatically by the system. The field name 
characterizes the content and is used for building the main 
menue of the training course. Directory describes the file 
location in the file system. Other significant columns are 
chapter id, which marks the relation of the chapter in the 
hierarchical tree structure (compare with Figure 1), order, 
number of questions and name long. As explaind by the 
name, the order field is responsible for the sequenze the 
learning path follows. Number of questions defines the 
amount of questions the student has to answer in the specific 
chapter throughout the test procedure, name long is used in 
the automatically generated table of content which forms the 
main menue of the training course (right column in Figure 8). 
Level of difficulty in the content table influences the 
sequence of the learning path. Depending on learners' 
capability a simplier or more advanced course is offered. An 
example of the MySQL user table is illustrated in Table 1. 
Metadata information about the author, keywords and date of 
creation are stored in a separate table which make the 
chapters re-usable in future. 
Corresponding to the entries in the database, all web pages 
are stored in the appropriate directory. Up to now this is 
handled manually, automatic support is planed in the future.