Topic and queue objects encapsulate specific information that directs the target and source of each message. This hierarchy is shown in Figure 1.

Topic和Queue对象封装了导向每条消息的目标和源的特定信息。

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Use a Data Access Object (DAO) to abstract and encapsulate all access to the data source.

使用数据访问对象来抽象和封装对数据源的所有访问。

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