| ////////////////////// |
| * Copyright (c) 2007-2012, Niclas Hedhman. All Rights Reserved. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, |
| * either express or implied. |
| * See the License for the specific language governing permissions |
| * and limitations under the License. |
| ////////////////////// |
| |
| [[core-api-entity,EntityComposite]] |
| = EntityComposite = |
| Entities are common in the object oriented programming world, but has never reached the stardom of Class and Object. |
| Instead we have seen many attempts at creating Entities on top of Java, such as EJB (3 incompatible versions), Java |
| Data Objects (JDO, 2 somewhat compatible versions), Java Persistence Architecture (JPA, 2 somewhat compatible versions), |
| Hibernate (4+ somewhat incompatible versions) and many other less known. This seems to suggest that the topic of |
| creating objects that survives over long periods of time is a difficult one. |
| |
| Eric Evans points out in his book that Entities is a very definite and distinct concept that needs to be handled |
| explicitly. Composite Oriented Programming in general, and Zest™ in particular, takes this point very seriously and |
| makes Entities a central part of the whole system. And likewise, we are convinced that it is not possible to develop |
| domain-knowledge-rich applications without a conscious and well-defined strategy on Entities. So, instead of spending |
| endless hours trying to get Hibernate mapping to do the right thing, we introduce a Composite meta type called |
| EntityComposite, which all entities must derive from, and by doing so automatically become persistable, searchable, |
| have a lifecycle and support nested undoable modifications. |
| |
| The characteristics of an EntityComposite compared to other Composite meta types are; |
| |
| * It has an Identity. |
| * It has a LifeCycle. |
| * It is typically persisted. |
| * It can only be referenced by an Association or ManyAssociation. |
| * Its CRUD operations are bound by a UnitOfWork. |
