Software Engineering – University of Tampere, CS DepartmentJyrki Nummenmaa INSTALLATIONS Software installation accommodates software to a target environment. Elements to be set up during installation may include: –Executables –Libraries –Help files / Manuals –Documentation –Application configuration files –System configuration files (like Windows registry) –Data files for the executable –Database

Software Engineering – University of Tampere, CS DepartmentJyrki Nummenmaa SYSTEM INSTALLATION Installation of a complete information system may, additionally, include e.g. –Hardware installations, –Training, –Organisational changes

Software Engineering – University of Tampere, CS DepartmentJyrki Nummenmaa Installation types Commissioning means first-time installation of software. Upgrading means replacing a version of the software with a later (and hopefully better) version. Downgrading means replacing a version with an older version. Uninstallation means removing the software altogether from the system.

Software Engineering – University of Tampere, CS DepartmentJyrki Nummenmaa Installation method examples Makefile –Designer of installation writes a file, which describes the files in the installation, the dependencies between files (E.g. file A needs files B and C etc.) and how to make files (E.g. make file A by gcc –g –o A B C) –The make program studies, which files are not up-to-date and makes them. Ant –From the Apache (web server) project –XML specification Installation wizard –A program, which – possibly interactively – runs the installation. –E.g. InstallShield for Windows.

Software Engineering – University of Tampere, CS DepartmentJyrki Nummenmaa What is a good installation like? The installed software works ”normally”. The installation does not affect the functionality of software, which has been installed earlier. (The installation should not create version incompatibilities in the configuration.) Creates minimal disruption to the environment and the all software in the system. Avoids selfish use of resources. Does not change the environment unnecessarily.

Software Engineering – University of Tampere, CS DepartmentJyrki Nummenmaa Further requirements for good installations Trace of what was done. Possibility to stop the installation and recover earlier state. Provide documentations, which explains the changes made in the system. This documentation should be available also before the actual installation starts.

Software Engineering – University of Tampere, CS DepartmentJyrki Nummenmaa Minimal disruption and unselfish resource usage Other software should continue to function. Avoid interrupts because of e.g. system reboots. Even simultaneous installations should be possible. Do not change general configuration files in a way that effects other software. Make minimal changes to the system. Use disk space and other resources sparingly. Respect the technical and political policies of the environment. Do not leave unnecessary things behind (temp files etc.).

Software Engineering – University of Tampere, CS DepartmentJyrki Nummenmaa Options Different types of media: HTTP, ftp, CD, etc… Setup options (and it should be possible to change them later): –functionalities –languages –visual effects –etc.

Software Engineering – University of Tampere, CS DepartmentJyrki Nummenmaa Minimum disruption to the usage of the system Minimize the time when the system can not be used (downtime, passive time). Some critical systems do not tolerate downtime at all. –It may be necessary to use a backup system when installing. For instance, when installing software to the mobile phone, it should be possible to use the phone for e.g. receiving incoming calls.

Software Engineering – University of Tampere, CS DepartmentJyrki Nummenmaa Preparing the installation Study the requirements – they may contain requirements for installation or other relevant information. The success of the installation depends largely on how the software has been built. Conclusion: The installation requirements should be taken into account when making the software – not only when the installation procedures are built and the software already exists! Particular difficulties are ahead, if we are making a large distributed system – then pay Test the installation procedures carefully.

Software Engineering – University of Tampere, CS DepartmentJyrki Nummenmaa Scheduling an installation Prepare for troubles: reserve extra time. Avoid disruption for users. Choose a quiet time. Inform in advance. Prepare for failure (backups!).