问题 问答题

阅读以下系统架构文档化的叙述,根据要求回答问题。
[说明]
软件架构(software Architecture)用来处理软件高层次结构的设计和实施。它以精心选择的形式将若干结构元素进行装配,从而满足系统主要功能和性能需求,并满足其他非功能性需求。软件架构为软件系统提供了一个结构、行为和属性的高级抽象模式,可以使用一个公式来表达:
软件架构=构成系统的元素,指导元素集成的形式,关系和约束
“4+1”视图模型用5个视图组成的模型来描述软件架构,如图3—15所示。


[问题2]
结合你的系统架构设计经验,请用300字以内的文字简要说明进程架构主要解决的问题,以及如何区分主要任务和次要任务。

答案

参考答案:进程架构考虑一些非功能性的需求,如性能和可用性等。它解决并发性、分布性、系统完整性和容错性的问题,以及逻辑视图的主要抽象如何与进程结构相配合在一起,即在哪个控制线程上,对象的操作被实际执行。
进程是构成可执行单元任务的分组。进程代表了可以进行策略控制过程架构的层次(即开始、恢复、重新配置及关闭)。另外,进程可以就处理负载的分布式增强或可用性的提高而不断地被重复。
主要任务是可以唯一处理的架构元素;次要任务是由于实施原因而引入的局部附加任务(如周期性活动、缓冲和暂停等)。它们可以作为轻量线程(或Ada Task)来实施。主要任务的通信途径是有着良好定义的交互任务通信机制:基于消息的同步或异步通信服务、远程过程调用及事件广播等。次要任务则以会话或共享内存来通信。在同一过程或处理节点上,主要任务不应对它们的分配做出任何假定。

阅读理解

阅读理解

     Going to outer space is a little like going camping.You have to carry with you all the food and

equipment you need for your trip, so your food can't be too heavy or hard to prepare.Plus, there are

no refrigerators to keep food cold and fresh.

     Food with all the water dried out is lightweight and doesn't spoil.So, many space foods are dried

on Earth and stored in special packets.Some, such as dried pears, taste good right out of the packet.

But to eat the turkey in this outerspace Thanksgiving dinner, an astronaut must add water and heat the

packets.

     On Earth, gravity is the force that keeps your feet on the ground and your sandwich on your plate.

But there's no gravity in space.To keep food from floating away, astronauts on the Space Shuttle attach

the packets to a special tray.The tray can be fixed to a wall or to the astronaut's lap.To prepare their

food, astronauts use liquid forms of salt and pepper.The liquid sticks to the food better.Regular salt

and pepper would float away, maybe up an astronaut's nose.Achoo!

     Liquids float right out of cups and glasses, though.So astronauts drink everything from a small bag

with a straw(饮料吸管) that can be closed.Astronauts say that most space foods taste pretty good.

Some, such as apples and pudding are the same as the foods you eat on Earth.

      Astronauts eat tortillas(玉米粉圆饼) instead of bread because they make fewer crumbs(碎屑).

Floating crumbs could get stuck in equipment or an astronaut's eye.

     Your body uses food in space the same way it does on Earth.Your body must get rid of waste in

space too.

     During take off and landing, astronauts can't leave their seats to go to the bathroom.They wear

diapers(尿布) under their spacesuits instead.

     The Space Shuttle has a bathroom the size of a small closet.The toilet has bars that keep astronauts

from floating away.

      A strong flow of air is used instead of water to flush waste down the toilet.Back on Earth it's flushed

away-or sometimes studied by scientists.

1. Why do astronauts use liquid forms of salt and pepper to prepare food?

A. Liquid doesn't spoil.

B. Liquid is convenient to use in space.

C. Liquid is lightweight.

D. Astronauts are in great need of water.

2. What do astronauts think of space foods?

A. Most of them taste pleasant.

B. They are mostly fruits.

C. Most of them are cold.

D. They contain little meat.

3. Why don't astronauts eat bread?

A. Bread tastes bad.

B. Tiny pieces may float.

C. Bread weights heavy.

D. Bread is rather hard to prepare.

4. We can infer from the passage that astronauts ______.

A. drink from cups and glasses

B. always wear diapers in space

C. can move freely during landing

D. must pay attention to the crumbs in space

问答题 简答题