Behavioral thingsare the dynamic parts of UML models. These are the verbs of a model, representing behavior over time and space. In all, there are three primary kinds of behavioral things.
行为元件是UML模型的动态部分．它们是模型的动词，代表在时间和空间的行为．主要有三类行为元件
First, aninteraction is a behavior that comprises a set of messages exchanged among a set of objects or roles within a particular context to accomplish a specific purpose. The behavior of a society of objects or of an individual operation may be specified with an interaction. An interaction involves a number of other elements, including messages, actions, and connectors (the connection between objects). Graphically, a message is rendered as a directed line, almost always including the name of its operation.
第一个交互行为，由一组消息构成，作用是为了达到某个目的，在对象集或角色之间交换指定文本．通过交互来指定外部对象或是个别操作的行为．交互包含大量的其它元素，其中包括消息，行动和连接器(连接两个对象)．消息的图形表现为一个带有方向的直线，直线上方通常总是显示操作的名称．
Second, astate machineis a behavior that specifies the sequences of states an object or an interaction goes through during its lifetime in response to events, together with its responses to those events. The behavior of an individual class or a collaboration of classes may be specified with a state machine. A state machine involves a number of other elements, including states, transitions (the flow from state to state), events (things that trigger a transition), and activities (the response to a transition). Graphically, state is rendered as a rounded rectangle, usually including its name and its substates, if any.
第二个状态机，这个行为用来说明对象或是交互响应某个事件期间的状态序列，同时也包含那些事件的应答．个别的类或是协作的类，它们的行为可能需要状态机来描述．状态机包含大量的其它元素，诸如状态，转换(从一个状态流转到另一状态)，事件(触发一个转换的事物)，活动(对一个转换的响应)．图形表现上，用一个圆角矩形框来表示状态，通常包含有该状态的名称，如果它有子状态的话，也将包含在里面．
Third, an activity is a behavior that specifies the sequence of steps a computational process performs. In an interaction, the focus is on the set of objects that interact. In a state machine, the focus is on the life cycle of one object at a time. In an activity, the focus is on the flows among steps without regard to which object performs each step. A step of an activity is called anaction. Graphically, an action is rendered as a rounded rectangle with a name indicating its purpose. States and actions are distinguished by their different contexts.
第三个活动，这个行为用来描述执行计算过程时所需步骤的次序．在交互中，关键点是对象们之间的相互作用；在状态机中，关键点是一个对象在一个时间点的生命周期．在活动中，关键点是对象自动执行每一步的过程．活动中的一个步骤被称为行动．在图形表现上，行动同样是由一个圆角矩形框代表，里面的名称用来标识行动的目标．状态和行动是通过它们的内容进行区分．
These three elements -- interactions, state machines, and activities -- are the basic behavioral things that you may include in a UML model. Semantically, these elements are usually connected to various structural elements, primarily classes, collaborations, and objects.
交互，状态机和活动是构建UML模型的基本行为元件的三个元素．语义上，这些元素通常用来连接各种不同的结构元素，主要类，协作和对象．
原文：http://blog.csdn.net/listen_snow/article/details/31370619