Updating Application Instance

Controller can update an application instance in case a suitable update package is available. Updating application instance supposes that the application of older version is replaced with the one of newer version, and the user settings and files of the old application are picked up by the new one. APS supports two types of application updates: patch and upgrade. Generally speaking, the difference is that patching supposes unattended instance update, while upgrading brings more serious changes to the instance and may require the user attendance. Application patch and upgrade are defined in detail by the Specification in section 4.3.13. Versions of package which can be updated to the current package. Depending on what kind of update is required - patch or upgrade - a Controller behavior slightly differs:

• When patching, the Controller skips reading new requirements, and preserves all resources allocated to the old version so that the new version could painlessly pick them all up, as defined by the Specification in section 4.4.4. Patch.
• When upgrading, the Controller analyzes new requirements and provides a mechanism of satisfying them together with migrating the application vitally-important data. (For example, when a new application version requires using a database of another version, the Controller provides mechanism of allocating the new database and migrating to it the old data.)