Application updater

I need an updater(update installer) for an already existing Windows application. The base app installation is an .msi made with InstallShield. The goal of the updater is just to (re)place some files on the target system, after checking if certain conditions are met. ## Deliverables The updater should work as follows: 1. Check if the base app is installed, this way: - look for and read a registry key (string value) containing a path to a folder - this is where the base app is installed. - check if this folder exists - check if a file with a certain name exists inside the folder If any of the above (the key, folder or file) is missing - the base app is considered as not installed. 2. If the base app is installed - the updater should extract the updated files to the folder stored in the registry key, unconditionally replacing existing files with the same names there. -If a file that has to replaced is in use, the updater should display a message about that, prompt the user to close the file and retry. -If after the first retry the file still can't be replaced - the installer should display a message and quit. -If the update was performed without problems, prompt the user to launch the application 3. If the base app is not installed, the installer should do this: - inform the user with a message (OK button only) - prompt the user to download the base app from a web location (Download/Cancel buttons) - start the download, if 'Download' button is clicked. Then display a message. (The download may be performed by simply passing the base installer url to the default browser. It should not be handled further). - Display another message, if 'Cancel' button is clicked. - quit 4. The installer should not do absolutely anything else. It should not modify the registry in any way, and should not modify whatever files except the ones that has to be updated. The desired result is an Inno Setup (or another free tool like Nullsoft installer) project, with all the scripts(well commented) and whatever else is needed. It may be in other form as well, as long as it meets the requirements. It may require Microsoft's Visual Studio 6 to build the updater. It should not require Borland products to build the updater. The following should be configurable by modifying a single file: - the list of files to be included in the updater, as full local file paths - the registry key to look for - the file to look for inside the folder obtained from the registry key value above - the url for downloading the base installer - the texts for all the messages, and the message boxes titles(captions) - the texts for all the controls displayed in the dialogs - like 'branding' texts and dialog titles. - the name of the file to be launched if the user chooses to launch the app after a successful update. The installer should work on a fresh installed Windows 98/98se/ME/2000/XP/2003 systems - that is, it should not rely on any files that are not included in the default Windows installations. 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Deliverables must be in ready-to-run condition, as follows (depending on the nature of the deliverables): a) For web sites or other server-side deliverables intended to only ever exist in one place in the Buyer's environment--Deliverables must be installed by the Seller in ready-to-run condition in the Buyer's environment. b) For all others including desktop software or software the buyer intends to distribute: A software installation package that will install the software in ready-to-run condition on the platform(s) specified in this bid request. 3) All deliverables will be considered "work made for hire" under U.S. Copyright law. Buyer will receive exclusive and complete copyrights to all work purchased. (No GPL, GNU, 3rd party components, etc. unless all copyright ramifications are explained AND AGREED TO by the buyer on the site per the coder's Seller Legal Agreement). ## Platform Windows 98/98se/2000/XP/2003