java - What is meant by mobility of entities? -
java - What is meant by mobility of entities? -
the book pro jpa 2 has mobile entities:
client/server , web applications , other distributed architectures popular types of applications in connected world. acknowledge fact meant acknowledging persistent entities must mobile in network. objects must able moved 1 virtual machine , again, , must still usable application.
objects leave persistence layer called detached. key feature of persistence model ability alter detached entities , reattach them upon homecoming virtual machine. detachment model provides way of reconciling state of entity beingness reattached, state in before became detached. allows entity changes made offline, while still maintaining entity consistency in face of concurrency.
can help me decode info in above 2 paragraphs? why 1 need entity move between jvm's?
the short reply there may multiple jvms (multiple mobile devices, multiple servers jvm, or combination thereof).
if understand correctly, consider illustration of save-game file. has business relationship website , has save file stored on site. person downloads game can play offline.
the save file @ point becomes 'detached entity'. updated 'offline', , reattached when user logs in website. updating entity stored server side may automatic, or user may prompted (do want overwrite save data? presents user 2 save files , timestamps).
other examples may include
health info mobile devices (updated when out of range of wireless) game data evernote/similar syncing services backup/restore services java jpa jpa-2.0
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