Migrating from one environment to another takes planning, resources, and, most importantly, time (except in very trivial cases). This implies that even when eventually migrating to another environment, coexistence among environments must be dealt with in the interim. In many companies it would make good business sense not to migrate legacy systems at all. Instead, it may be better to develop new systems in the desired environment and let the legacy applications be phased out. The data created by the legacy applications is important and ways to ensure that data from the new environment can be accessed are important. Coexistence considerations are very important in this case.