In today's companies, most projects can no longer be realized by an individual alone but they are solved in a team. However, most user programs do not, or at best do only insufficiently support cooperate procedures. As a result, the user itself is solely responsible for an efficient communication as well as for the consistency of shared documents and information.

Due to the success of the World Wide Web (W3) in the past few years, the internet has become significantly more important as a platform for the development of CSCW-systems (Computer Supported Cooperative Work). Thus today we can already find a great number of supporting applications used for cooperative work.

In a first step we analyzed and characterized the communication behavior of user groups of news and mail systems. Further we studied the feasibility of a web-integrated solution for the support of group communication in regard of our implementation, called eForum.

The main purpose of our eForum is to coordinate and manage information of teams and common interest groups. It is an electronic support for coordination and teamwork. It allows the geographically distanced participants to share ideas and information asynchronically.

Our communication forum has the following major functions:

• Authorization & administration
• User friendliness
• Explicit group structure
• News forum with news, attachments and votings
• Document management

The task was to analyse a given system for the transfer of data and to prepare proposals for solutions for a more efficient data communication. A "demonstrator" was available, which simulated a transmission circuit to transmit data. The server and the client (display) communicate using CORBA. A complete data record is transmitted uncompressed each time.

The new "demonstrator" functions parallel with the old. The data communication takes place by means of UDP (User Datagram Protocol), in order to be computer independent. The data is transmitted periodically to all displays, where each has its own port address.

To transfer the data more efficiently there are basically two main aspects: Data reduction and data compression. On the one hand to reduce the data a cache is used, so that only modified data will be transferred. On the other hand a dictionary, with which the most frequent words, e.g. station names, are replaced by an index. Data compression is done using our own static Huffman procedure, with which the available characters are coded with a different bit number (dependent on their frequency).

A comparison with the old "demonstrator" resulted in a clear reduction of the transferred quantity of data; it was reduced to 15-50% of the original data. The average under normal operation is approx. 20%. To transfer the same quantity of data as the old "demonstrator", a text with approx. 75 characters could be transferred.

As final analysis of the diploma we can say that our suggestions contain many aspects that can be implemented easily for more efficient data transfers. Our solution is efficient and should be simple to understand. We attached importance to make as few restrictions as possible for extensions so that our work can be used as base and suggestion for the today's or future system.

The premises of a school are one of its most important resources. Thus it is not surprising that the administration of the same can be quite time-consuming. Primarily, the rooms are needed for the daily use of the school lectures as printed in the timetable. In addition, there are other reservations such as for experiments and demonstration lectures, school meetings and external courses. The data from the timetable can be seen on an existing Database on the Internet. For all further reservations the administration office has to be called to check the availability of the room and to make the reservation.

With our new Room Reservation System external and internal customers can make their reservations directly by Internet. This facilitates the work for the administration office as well as the customer.

The characteristics of the rooms are stored in an Oracle database. SQL search queries are used to collect information from our Oracel database, as well as from the timetable database. The reservations of rooms or the modification of attributes can easily be carried out on graphic surfaces.The room reservation system covers the essential functions to manage rooms efficiently. Rooms can be reserved, a fast overview can be given and bills can be mailed.

This dissertation entails a broad field of webpublishing issues and can easily be extended in a later work.

The Internet has evolved from a text-based data network to a multimedia net that is being used to transmit images, audio and video. It is obvious to make phone calls over the Internet as well. Corporate networks are always connected to the Internet through a firewall. The firewall has to be overcome in order to establish phone connections between two arbitrary participants connected to the Internet at some place on earth.

The goal of our project was to overcome the Linux firewall. This implicated the development of a firewall module that enables an H.323 connection through the firewall. Our solution to solve this problem is the dynamic opening of ports on demand, closing them when the connection is terminated.

In order to find out which ports are concerned, the H.323 messages are analysed. The firewall is then informed which ports it has to open. The firewall has to be told which IP packets it has to pass to the module so that they can be analysed. Other packets are not examined.

Our module currently supports connections between Siemens IP phones. The calling party has to be inside the firewall. Multiple concurrent connections are possible. NetMeeting is not supported yet. It uses an H.323 feature that our module is not capable of understanding at the time. All connections are logged to a file.

Many buses in public transportation use a announcement system for the next bus stop. The computation of the vehicle's position is done today by getting the impulses from a wheelsensor. This method causes some disadvantages. In that case we have to assume that the vehicle is always on the correct route. An additional error can occur from the environmental conditions and different shapes of the wheels.

Our Task was to develop a test system, that will detect an off-route-condition and announce the forthcoming stop. Also the application should consist of two parts. Firstly a planning tool to record a route and adapt it to the correct format. Secondly the detection tool to detect the off-route-condition, given a route (from the planning tool) and the currently measured point. The system requirements should be as small as possible, because the onboard computer has limited capacities. Both applications should be developed in C++ for the 80x86 platform, so they can later be ported (by Häni-Prolectron AG) to the onboard computer having a Windows CE operating system.

To be able to estimate the precision and errors of a GPS-system, we did some early test drives, to gather information and data. These routes have been captured for later evaluation. After knowing the possible errors and the possibilities, we could start developing the algorithms and an application for testing purposes.

The final result of our work is an application, that combines the two components planning tool and detection tool. Among the functions are capturing of a route, saving routes to a file, graphical display and other processing functions. To get better routes and detection results, the application is capable of calculating an average of multiple routes (to eliminate single measurement errors) and of reducing routes to a necessary minimum of size (to reduce file size).

IPC@CHIP is a matchbox-sized single chip computer (80186, 20 MHz, 256 KB of flash memory, 512 KB of RAM) featuring an Ethernet interface and 24-volt IO ports. Hence it is possible to connect appliances to the Internet and to transfer data. Consequently, security issues become of major importance. Access must be restricted to authorized personnel, and the entire transmission has to be encrypted.

This is precisely the goal of our diploma project: Development of a web server capable of encrypting the entire data transmission using SSL, despite the lack of powerful hardware.

The first task was the porting of OpenSSL to the IPC@CHIP platform. Because of the limited hardware this task turned out to be very complex. The original OpenSSL library (larger than 1.5 MB) had to be reduced to a few hundred kilobytes. The entire ASN.1 and X.509 part of the library was removed because we implemented our own functions for handling certificate and private key. To reduce code size a special format was developed for the storage of the private key. In addition, a tool was developed to convert private keys from the old format into the new one.

Because of License Agreements the IPC@CHIP web server could not be equipped with SSL. Therefore we developed our own web server with CGI support. Due to lack of space no client authentication was implemented, and so the user?s identity must be checked in a CGI program (login name and password are transmitted securely). As the CGI interface is compatible with the IPC@CHIP web server, all present CGI programs written for IPC@CHIP are executable on our web server.

The result of our diploma project is a tiny (101 kilobytes), fully functional, CGI-capable web server supporting SSL handshake and encoding. The used cipher suite (RSA, RC4 128-bit) is nowadays considered to be very safe and is widely used. Thus no more restrictions are set on the usage of IPC@CHIP, not even for safety-relevant applications.

Security Gateways form the endpoints of secure IPsec connections in a Virtual Private Network (VPN). Similar to a router a security gateway decidesan a basis of configurable rules how to treat an incoming or outgoing IP packet. This rules, called Security Policies, are saved in a Security PolicyDatabase (SPD).

In this diploma project we had the task to design an expert diagnosis tool for security policies and to implement it in Microsoft Visual C++ (including a graphical user interface). This expert tool is going to be used by our industrial partner Omnisec AG to check their security policies before they are loaded into a device of the product family Omnisec 41x.

First we analysed all possible errors and inconsistencies that can occur in a distributed network security policy (i.e. splitted in several local security policies). Then we worked out possible solutions for each problem. This solutions were later integrated in our expert tool.

Based on the Omnisec interface definitions we developed our expert tool, which contains following functionality:

The whole SPD is loaded in our program. Then we check the SPD for errors and inconsistencies. In the case of errors or inconsistencies, they are marked red and commented with a problem description.

We invested the most time in programing and testing our expert tool. This allowed us to gain valuable experience in software design and localization of errors.

Remote maintenance of systems is not to be excluded any longer for many companies. It enables a monitoring from a central location.

With the company NTI AG an industrial partner was found, which wants to monitor linear motors and the pertinent servo controllers over a remote maintenance system. In a first phase a monitoring over the Internet with an additional hardware, an Embedded system with Java Virtual Machine is to be implemented. Monitoring means the recalling of actual parameters. These parameters are to be represented in a webbrowser and interpreted by the user. In a further phase a configuration of the servo controller is to be enabled by Internet with the provided software LinMot Commander. The existing software in server mode enables remote maintenance. However its disadvantage is, that a workstation is used for it. The software had to be implemented and simplified therefore on a more favourable target system. Here the Embedded system TINI (Tiny Inter Net Interface) was used.

The emphasis in the practical work was put on an application for customers of the company NTI AG. The Application is executable in a webbrowser and enables a monitoring of the servo controller. In the implemented system the monitoring could be carried out with a Java Applet in the webbrowser which can recall the data from any location. The software was arranged modular, so that future modifications can be executed easily and the system can be maintained without problems. A configuration from the distance with the supplied software could not be implemented up to the end of the thesis (diploma). Reason for it is the insufficient performance of the TINI what cause timeouts.

The company QualiCasa operates a measuring system with the aim for capturing of real estate data from the building design aspect. With these data they create an exact status report of the buildings to perform a direct investment budgeting of real estates.

A mobile, software supported measuring system which enables the data acquisition in a simple manner has to be implemented. A target is to replace the wires which connect the measurement equipment with a radio link to test current values of the measuring instruments or to switch the devices. A further target is the development of an entry and a control software for the controlling of the external devices.

The main purpose in this (diploma) thesis is the implementation of a prototype to demonstrate a complete measurement. Therefore the communication between measuring instruments and the entry software had to be analysed and determined. In a further step the needed software was analysed, designed and implemented. Parallel to this work a print was engineered for interface adaptation between PC and the DECT module. A mechanical, as well as an electrical integration of the DECT module at a laptop were implemented. The analysis of the communication served as a base for an external order which had to be assigned and controlled.

With "VisualAge for Java", the design of the graphical user interface, the control of the "Hammerwerk" for the "Trittschall" measurement, the status indication of the radio link and capturing the measured data could be created.

Within the last few months companies followed the trend to connect their local networks stationed at different locations. The used technology is called Virtual Private Network or short VPN. These connections have to fulfill certain criterions as low cost, data security and large band-width. The Internet is a low cost medium with enough band-width but lacks in data security. Encryption provided by security gateways is the solution.

The task was to simulate a VPN with two local networks and create data traffic to test the security gateway. Each local network was represented by a single computer. The first computer creates the necessary data traffic and sends it via the security gateways to the other computer.

To create the data packages we programmed a Application Program Interface (API) which is able to produce packages of our choice and send them to another network. The API supports the IP protocol version 4 as well as the IP-based protocols TCP, UDP and ICMP. The simulation is able to simulate any network. We defined a own script language to use the necessary parameters. A parser is analyzing and preparing these scripts for the simulation.

Häni Prolectron AG develops control systems for vehicles of public transport service. For the communication between the master board computer and the spread slave devices - i.e. ticket control unit and bus stop signal - a data bus is used, which the slaves must be physically connected to. This diploma project is investigating on whether it is possible to install a wireless radio system as an alternative to the expensive wire system.

The goal of the analysis is to design a system with either DECT or Bluetooth radio technology which perfectly the data bus in use. Therefore the current system was analysed in order to get the criteria for designing the new wireless system.

According to this framework 5 connectionoriented and 4 connectionless systems were designed and the feasibility of every one was checked against the standards of the two technologies. With both of them a bus emulation can be realised. With DECT there is developpment needed, becaus there is no suitable hardware avaiable. With Bluetooth this can not yet been said. In order to find out about characteristic network behaviour a demo system was realised with a Siemens DECT Engine MD32.

As a result our diploma project weights up the possibilities and limits of these 9 systems for data bus emulation.