Note on writing another DAO

You can add easily another database as a background for NemakiWare.

• Replace jp.aegif.nemaki.service.dao.impl.CouchContentDaoServiceImpl/CouchPrincipalDaoServiceImpl.
  ContentDaoServiceImpl/PrincipalDaoServiceImpl implement the caching mechanism and call CouchContentDaoServiceImpl/CouchPrincipalDaoServiceImpl as nonCachedContentDaoService/nonCachedPrincipalDaoService.

• DAO service classes should implement ContentDaoService/PrincipalDaoService interface.

• Spring configuration
  context.backend in property files: Overwrite it by the new Spring context file you defined.
  Your new Spring context file: Define the classes as couchContext.xml.

• Methods in you DAO should return null(or empty list) when they have any error or no result.
  In the higher layer, the result is checked by CollectionUtils.isEmpty.