1.44.1. Notes on Value storage usage:

Value storages are pluggable to the container but if they are used, the container implementation should respect set of interfaces and external storage usage principles.

If the container has ValueStoragePluginProvider (e.g. via constructor), it's just a few methods to manipulate external Values data.

// get channel for ValueData write (add or update)

ValueIOChannel channel = valueStorageProvider.getApplicableChannel(data,  i);

if (channel == null) {

  // write

  channel.write(data.getIdentifier(),  vd);

  // obtain storage id,  id can be used for linkage of external ValueData and PropertyData in main backend

  String storageId = channel.getStorageId();

}


....


// delete all Property Values in external storage

ValueIOChannel channel = valueStorageProvider.getChannel(storageId);

channel.delete(propertyData.getIdentifier());


....


// read ValueData from external storage

ValueIOChannel channel = valueStorageProvider.getChannel(storageId);

ValueData vdata = channel.read(propertyData.getIdentifier(),  orderNumber,  maxBufferSize);

Important

After a sequence of write and/or delete operations on the storage channel, the channel should be committed (or rolled back on an error). See ValueIOChannel.commit() and ValueIOChannel.rollback() and how those methods are used in JDBC container.