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1.4 Introducing BPMN 2.0 from a developers viewpoint（從開發者的角度介紹BPMN 2.0）

To become familiar with the important constructs of BPMN, we’ll build up the detail level of modeling similar to the categorization of WfMC and Bruce Silver. First, we start with a high-level model example and then we dive into a more detailed process. Level 3 of the Bruce Silver categorization will be discussed in section 1.5, when we will implement our first process with the Activiti process engine.

為了熟悉BPMN重要的構件，我們將構件和WfMC和Bruce Silver分類相似的詳細的建模層次。首先，我們以一個高層建模示例開始，而后我們專研一個更詳細的流程。Bruce Silver分類的層次將在節1.5討論，然后我們將用Activiti流程引擎實現第一個流程。

1.4.1 High-level modeling with BPMN 2.0 （采用BPMN 2.0進行高級建模）

In section 1.1 we looked at a sample book order business process. In figure 1.1 the book order process was modeled without a real model notation. With the simple or level 1 palette in mind, we’ll take another look at the book order process and convert it into a real BPMN 2.0 business process model.

節1.1，我們討論了一個訂書業務流程的示例。在圖1.1中，訂書流程的建模沒有采用實際的模型符號。采用簡單的或者級別1調色板，我們將用另外的方式討論訂書流程，并將它轉換成BPMN 2.0的業務流程模型。

This means that we have to add a more formal notation to describe the book order process. So in the BPMN 2.0 book order process we’ll use start and end events, parallel gateways, pools and tasks. Figure 1.7 shows the book order process modeled with a simple subset of the BPMN 2.0 palette.

這意味著我們不得不增加正式符號描述訂書流程。所以，在BPMN 2.0訂書流程，我們將使用開始和結束事件，并行網關，泳池和任務。圖1.7展示了采用一個BPMN2.0調色板子集建模的訂書流程。

Figure 1.7 A high level BPMN 2.0 model describing the book order process with a simple subset of the BPMN 2.0 construct palette.

圖 1.7 采用BPMN 2.0 構件調色板簡單子集描述訂書流程的高級BPMN 2.0模型

Before discussing the process in more detail let’s first look at the individual BPMN 2.0 constructs in table 1.1.

在詳細討論流程之前，讓我們首先看看表1.1中的單個BPMN 2.0構件 

Table 1.1 Overview of the BPMN 2.0 constructs used in figure 1.7.

表1.1 在圖1.7中使用的BPMN 2.0構件的概貌

BPMN 2.0 icon	BPMN 2.0 name	Description
	Start event 開始事件	A start event is the trigger to start a new process instance. 開始事件是啟動一個新流程實例的觸發器
	End event 結束事件	An end event is the last step before the process instance is completed. The end event has a thicker circle border line than the start event. 結束事件是流程實例完成之前的最后一步。結束事件的邊線要比開始事件要粗。
	Pool 泳池	A pool represents the container for the activities of a process. Best practice is to use the process name for the pool name. 泳池表示流程活動的容器。使用流程名作為泳池名是最佳實踐。
	Lane 泳道	A lane represents a role within a process model. In most cases this is a organizational unit or a role definition. 泳道代表流程模型里的角色。在大多數情況下，這是一個組織單元或者角色定義。
	Task 任務	A task is a piece of work that has to be executed as part of the process definition. A task can be an automated activity or a manual activity. 任務是作為流程定義部分可執行工作的片段。任務既可為自動任務，也可為人工任務。
	Parallel gateway 并行網關	A parallel gateway is used to indicate that activities can be executed simultaneously or that all incoming activities must be completed before the process progresses to the next activity. 并行網關用來指示可同時執行的活動，或者在流程行進到下個活動的所有傳入活動。
	Exclusive gateway 排他網關	An exclusive gateway is used for conditional logic. Based on a condition only one of the outgoing sequence flows will be followed. 排他網關用來處理條件邏輯。基于條件，只有一個傳出順序流得到執行。
	Message flow 消息流	A message flow is used to send a signal or message from one pool to another. It may not be used to connect activities within one pool. 消息流用來從一個泳池到另一個泳池發送信號或者消息。它不可以在一個泳池連接活動。
	Sequence flow 順序流	A sequence flow connects activities, gateways and events to each other within one pool. It therefore represents the orchestration of the process definition. 順序流連接在同一個泳池里的活動，網關和事件。所以它代表了流程定義的編排。

Now we know the meaning of the individual BPMN 2.0 constructs let’s walk through the full process model. One of the eye-catching differences between the model we’ve drawn in section 1 and figure 1.7 is the use of pools and lanes. In figure 1.7 there are three pools: Customer, Book store and Publisher. The pools describe the different roles that perform activities in the business process. In the book store pool there are two lanes that characterize the different organizational units within the book store. Because in this example the bookstore is a small company, there’s only a sales and an inventory organizational unit.

既然我們知道單個BPMN 2.0構件的意義，讓我們遍歷全部的流程模型。在我們于圖1.7中所繪的模型使用了泳池和泳道。圖1.7有三個泳池：客戶，書籍和出版商。泳池是業務流程中執行活動的不同角色。在書店泳池里有兩個泳道，對書店里不同的兩個組織單元進行特性化。因為本示例中，書店是一個小公司，所以只有銷售和庫房兩個組織單元。

In this business process model we focus on the book store, but we could also include the process activities that are necessary for the publisher to complete the order process. The process is started with a order request by a customer, which is pictured here as a message flow (the dashed line) initiating a start event (a circle).

在業務流程模型中，我們關注書店，但也包括為出版商完成訂單流程的流程活動。流程由一個客戶啟動。在此繪制為一個消息流（虛線）來啟動一個開始事件（一個圓圈）。

When the process is started two tasks should be completed, which are the process payment and the check stock tasks. These tasks can be executed in parallel and therefore a parallel gateway is modeled after the start event. After the stock is checked an exclusive gateway is used for the conditional logic of the book being in stock or not. When the book is not in stock it’s ordered from the publisher by an additional task.

當流程啟動時，應當完成兩個任務。它們是支付任務和存貨檢查任務。因為這些任務可以并行執行，所以在開始事件之后，建模為平行網關。在存貨檢查之后，用一個排他網關進行書籍是否有庫存的條件邏輯的判斷。當書籍沒有庫存，則通過另外的任務從出版商訂貨。

When the book is in stock, either because it was already or by an extra order via the publisher, the book is ready for shipment. But before the book will be shipped we must be sure that the payment has been successfully completed. So a parallel gateway is used to join the tasks, meaning that the process will go further before these tasks have been completed.

當書籍有庫存，或者是因為書籍已準備就緒，或者是因為通過出版商的額外訂貨，書籍可以準備發貨。但是，在書籍發貨之前，我們必須確定支付已成功完成。所以并行網關用來聚合任務。在這些任務完成之前，將會向前推進。

After the parallel gateway two additional tasks are executed that ship the book to the customer and inform the customer about the arrival date before the process is completed by an end event. As you see the high level model doesn’t contain stuff like error handling or the definition of the type of a task. That’s what we will add in the next section.

在兩個額外任務的并行網關執行之后，在通過一個結束事件完成流程之前，把書籍發送給客戶，并通知客戶到貨的日期。正如你所見，高級模型并不包括錯誤處理或者任務類型定義之類的事情。那是我們在下節討論的內容。