370 - 架构匹配 Flashcards

Question

subsystems

Answer 1

Logical View

Answer 2

Logical View

Answer 3

Logical View

Answer 4

Logical View

Answer 5

Logical View

Answer 6

* Logical elements organized in terms of * components, layers, subsystems, packages, frameworks, class, and interfaces 按组件、层、子系统、包、框架、类和接口组织的逻辑元素 * Addresses the functional requirements of the system 处理系统的功能需求 * “What should the system do for its end users?” “系统应为最终用户提供什么？” * An abstraction of the design model 设计模型的抽象 * Identifies major design packages, subsystems and classes 确定主要设计包、子系统和类 * Interaction diagrams are used to illustrate significant system collaborations 使用交互图展示系统的显著协作

Answer 7

Description: 1. Their associated primitive operations are encapsulated in an abstract data type or object.数据表示及其关联的基本操作被封装在一个抽象数据类型或对象中。 2. Objects are examples of a sort of component we call a manager because it is responsible for preserving the integrity of a resource.对象是一种我们称为管理者（manager）的组件，因为它负责维护资源的完整性 3. Objects interact through function and procedure invocations. 对象之间通过函数和过程调用进行交互。通过类和对象组织代码，封装数据和操作，利用继承，封装，多态等特性来提高代码的复用性。 Pros: 1. An object is responsible for preserving the integrity of its representation 2. The representation is hidden from other objects. 3. Some systems allow “objects” to be concurrent tasks 4. Others allow objects to have multiple interfaces 5. An object hides its representation from its clients, it is possible to change the implementation without affecting those clients Cons: 1. In order for one object to interact with another (via procedure call) it must know the identity of that other object. 2. Whenever the identity of an object changes it is necessary to modify all other objects that explicitly invoke it. Call-and-return systems

Answer 8

Description: The idea behind implicit invocation is that instead of invoking a procedure directly, a component can announce (or broadcast) one or more events. Other components in the system can register an interest in an event by associating a procedure with the event. When the event is announced the system itself invokes all of the procedures that have been registered for the event. Thus an event announcement ``implicitly'' causes the invocation of procedures in other modules. 隐式调用的背后理念是，组件不直接调用过程，而是宣布（或广播）一个或多个事件。系统中的其他组件可以通过将一个过程与事件关联来注册对该事件的兴趣。当事件被宣布时，系统会自动调用所有已为该事件注册的过程。因此，事件的宣布“隐式地”导致了其他模块中过程的调用。 A component can announce (or broadcast) one or more events. Other components in the system can register an interest in an event by associating a procedure with the event. Examples: react to pushing a button; Debugging systems (listen for particular breakpoints) pros: 1. One important benefit of implicit invocation is that it provides strong support for reuse. 隐式调用的一个重要好处是，它为重用提供了强有力的支持。 2. implicit invocation eases system evolution. Components may be replaced by other components without affecting the interfaces of other components in the system. 组件可以被其他组件替换，而不影响系统中其他组件的接口。 Cons: 1. The main invariant of this style is that announcers of events do not know which components will be affected by those events. Thus components cannot make assumptions about order of processing, or even about what processing, will occur as a result of their events.这种风格的主要不变特性是事件的宣布者并不知道哪些组件会受到这些事件的影响。因此，组件不能对处理顺序或这些事件引起的处理类型做任何假设。 2. implicit invocation is that components relinquish control over the computation performed by the system. 组件放弃了对系统执行的计算的控制。 3. When a component announces an event, it has no idea what other components will respond to it. Worse, even if it does know what other components are interested in the events it announces, it cannot rely on the order in which they are invoked. Nor can it know when they are finished. 当一个组件宣布事件时，它并不知道哪些其他组件会响应该事件。更糟的是，即使它知道哪些其他组件对其宣布的事件感兴趣，它也不能依赖它们被调用的顺序，甚至无法知道它们何时完成。 4. Another problem concerns exchange of data. Sometimes data can be passed with the event. But in other situations event systems must rely on a shared repository for interaction. In these cases global performance and resource management can become a serious issue. 另一个问题涉及数据交换。有时数据可以与事件一起传递。但在其他情况下，事件系统必须依赖共享存储库进行交互。在这些情况下，整体性能和资源管理可能成为严重的问题。例子：User interface (GUI)，Debugging System监听特定断点 Independent components

Answer 9

Description: Each layer that provides service to the layer above it and serves as a client to the layer below it. 每一层为其上的层提供服务，并作为其下层的客户端。层与层之间的交互通常限制为相邻层之间。 In some layered systems inner layers are hidden from all except the adjacent outer layer, except for certain functions carefully selected for export.在一些分层系统中，内层对所有其他层（除相邻的外层）都是隐藏的，只有某些精心挑选的功能可以被导出。因此，在这些系统中，组件在层级结构的某一层实现了一个虚拟机。 pros： First, they support design based on increasing levels of abstraction. This allows implementors to partition a complex problem into a sequence of incremental steps. 首先，它们支持基于逐级抽象的设计。这允许实现者将复杂问题分解为一系列渐进的步骤。 They support enhancement. Like pipelines, because each layer interacts with at most the layers below and above, changes to the function of one layer affect at most two other layers. 它们支持增强功能。像流水线一样，由于每层最多只与上下相邻层交互，对一层功能的更改最多只影响另外两个层。 They support reuse. Like abstract data types, different implementations of the same layer can be used interchangeably, provided they support the same interfaces to their adjacent layers.它们支持复用。像抽象数据类型一样，相同层的不同实现可以互换使用，只要它们支持相邻层的相同接口。 Cons： Not all systems are easily structured in a layered fashion. (We will see an example of this later in the case studies.) And even if a system can logically be structured as layers, considerations of performance may require closer coupling between logically high-level functions and their lower-level implementations. 并非所有系统都能轻松地结构化为分层方式。（在后续案例研究中，我们将看到一个例子。）即使一个系统在逻辑上可以结构化为层，性能的考虑可能要求逻辑上高层的功能与其低层实现之间更紧密的耦合。例子： OSI 模型：开放式系统互联模型，它将网络通信分为7层通信协议（Communication Protocol）：一系列规则和约定，它规定了数据传输的格式，顺序，处理方式以及错误处理机制。操作系统数据库的访问层和逻辑层 Call-and-return systems: Main program and subroutine; OO systems; Hierarchical layers

Answer 10

In a repository style there are two quite distinct kinds of components: a central data structure represents the current state, and a collection of independent components operate on the central data store. 在仓库风格中，有两种截然不同的组件类型：一个中央数据结构表示当前状态，一组独立组件在中央数据存储上进行操作。黑板模型通常由三个主要部分组成： The knowledge sources: separate, independent parcels of applicationdependent knowledge. Interaction among knowledge sources takes place solely through the blackboard.知识源：独立、分离的应用依赖知识单元。知识源之间的交互仅通过黑板进行。 The blackboard data structure: problem-solving state data, organized into an application-dependent hierarchy. Knowledge sources make changes to the blackboard that lead incrementally to a solution to the problem.黑板数据结构：问题解决状态数据，按照应用相关的层次结构组织。知识源对黑板进行更改，这些更改逐步引向问题的解决。 Control: driven entirely by state of blackboard. Knowledge sources respond opportunistically when changes in the blackboard make them applicable.控制：完全由黑板的状态驱动。当黑板的变化使知识源适用时，知识源就会主动响应。一个黑板组件作为中央数据存储库，并且有一组独立的计算组件，这些组件独立地作用于存储在平台上的公共数据结构，响应其中的变化并进一步响应后续的变化。其工作方式是内部有一个非常类似于数据库的组件。你有一个大单元，然后有不同的模块或代理，通常这些是虚拟模块、虚拟代理。所以我有一个大任务，我将它分配给这些不同的虚拟代理或虚拟模块。这就是黑板架构的存储库。它不是数据库。例子： Speech recognition with multiple knowledge sources * Image recognition with multiple knowledge sources * Programming environments with shared repository of programs and program fragments 现代编译器 Data-centered-systems(repositories): Databases; Hypertext systems; Blackboards