第七章云基础设施机制

云基础设施机制：
（1）逻辑网络边界
（2）虚拟服务器
（3）云存储设备
（4）云使用监控
（5）资源复制
（6）已就绪环境

7.1逻辑网络边界

逻辑网络边界（logical network perimeter）被定义为将一个网络环境与通信网络的其他部分隔离开来，形成了一个虚拟网络边界，它包括并隔离了一组相关的基于云的IT资源，这些资源在物理上可能是分布式的。
该机制被用于：
*将云中的IT资源与非授权用户隔离
*将云中的IT资源与非用户隔离
*将云中的IT资源与云用户隔离
*控制被隔离IT资源的可用带宽
该机制包括：
（1）虚拟防火墙（virtual firewall）——一种IT资源，可以主动过滤被隔离网络的网络流量，并控制其与Internet的交互。
（2）虚拟网络（virtual network）——一般通过VLAN形成，这种IT资源用来隔离数据中心基础设施内的网络环境。

7.2虚拟服务器（virtual service）

虚拟服务器是一种模拟物理服务器的虚拟化软件。
A virtual server is a form of virtualization software that emulates a physical server.
通过向云用户提供独立的虚拟服务器实例，云提供者使多个云用户共享同一个物理服务器。
（相同于 虚拟机（VM））

通过安装或释放虚拟服务器，云用户可以定制自己的环境，这个环境独立于其他正在使用由同一底层物理服务器控制的虚拟服务器的云用户。
Cloud consumers that install or lease virtual servers can customize their environments independently from other cloud consumers that may be using virtual services hosted by the same underlying physical service
.

7.3云存储设备（cloud storage device）

云存储设备机制是指专门为基于云配置所设计的存储设备。

7.3.1云存储等级

常见的数据存储逻辑单元：
（1）文件（file）——数据集合分组存放于文件夹中的文件里。
（2）块（block）——存储的最低等级，最接近硬件，数据块是可被独立访问的最小数据单位。
（3）数据集（dataset）——基于表格的、以分隔符分隔的或以记录形式组织的数据集合。
（4）对象（object）——将数据及其它相关的元数据组织为基于Web的资源。
 

7.3.2网络存储接口

7.3.3对象存储接口

各种类型的数据都可以作为Web资源被引用和存储，这就是对象存储，它以可以支持多种数据和媒体类型的技术为基础。

7.3.4数据库存储接口

主要有两种类型：
（1）关系数据存储(Relation Data Storage)
关系数据库依靠表格，将相似的数据组织为行列形式。
Relational databases rely on tables to organize similar data into rows and columns.
（2）非关系数据存储(Non-relation Data Storage)
非关系数据存储与传统关系数据库模型相比有较大差异，它采用更加松散的结构来存储数据，不强调定义关系和实现数据规范化。
Non-relational database storage established a “looser” structure for stored data with less emphasis on defining relationships and realizing data normalization.
 

7.4云使用监控

云使用监控机制是一种轻量级的自治软件程序，用于收集和处理IT资源的使用数据。
The cloud usage monitor mechanism is a lightweight and autonomous software program responsible for collecting and processing IT resource usage data.

7.4.1监控代理（monitoring agent）

是一个中间的事件驱动程序，它作为服务代理驻留在已有通信路径上，对数据流进行透明的监控和分析。

7.4.2资源代理（resource agent）

是一种处理模块，通过与专门的资源软件进行事件驱动的交互来收集使用数据。
A resource agent  is a processing module that collects usage data by having event-driven interactions with specialized resource software.

7.4.3轮询代理（polling agent）

是一种处理模块，通过轮询IT资源来收集云服务使用数据。
A polling agent  is a processing module that collects cloud service usage data by polling IT resources.

 

7.5资源复制

复制被定义为对同一个IT资源创建多个实例，通常在需要加强IT资源的可用性和性能时执行。
使用虚拟化技术来实现资源复制（resource replication）机制可以复制基于云的IT资源。

7.6已就绪环境

已就绪环境机制是PaaS云交付模型的定义组件，它代表的是预定义的基于云的平台，该平台由一组已安装的IT资源组成，可以被云用户使用和定制。
The ready-made environment mechanism is a defining component of the PaaS cloud delivery model.
The ready-made environment represents a pre-defined, cloud-based platform comprised of a set of already installed IT resources, ready to be used and customized by a cloud consumer. 
云用户使用这些环境在云内远程开发和配置自身的服务与应用程序。
These ready-made environments are utilized by cloud consumers to remotely develop and deploy their own services and applications within a cloud.
典型的已就绪环境包括预安装的IT资源，如数据库、中间件，开发工具和管理工具。
 
典型例题：
一、判断题
1.  A virtual server is a form of virtualization software that emulates a physical server. ( T  )
2. Cloud consumers that install or lease virtual servers cannot customize their environments independently from other cloud consumers. ( F   )
(Cloud consumers that install or lease virtual servers can customize their environments independently from other cloud consumers.)
3. Non-relational databases rely on tables to organize similar data into rows and columns. ( F  )
( Relational databases rely on tables to organize similar data into rows and columns.)
4. Non-relational database storage establishes a “looser” structure for stored data with less emphasis on defining relationships and realizing data normalization. (  T )
5. The cloud usage monitor mechanism is a lightweight and autonomous software program responsible for collecting and processing IT resource usage data. ( T  )
6. A polling agent  is a processing module that collects usage data by having event-driven interactions with specialized resource software. (  F  )
(A resource agent  is a processing module that collects usage data by having event-driven interactions with specialized resource software.)
7. A resource agent  is a processing module that collects cloud service usage data by polling IT resources. ( F  )
（A polling agent  is a processing module that collects cloud service usage data by polling IT resources. ）
8. The ready-made environment mechanism is a defining component of the IaaS cloud delivery model. (  F  )
（The ready-made environment mechanism is a defining component of the PaaS cloud delivery model. ）
9. The ready-made environment represents a pre-defined, cloud-based platform comprised of a set of already installed IT resources, ready to be used and customized by a cloud consumer. (  T )
10. These ready-made environments are utilized by cloud consumers to remotely develop and deploy their own services and applications within a cloud. ( T  )
二、选择题
1. The     A     is defined as the isolation of a network environment from the rest of a communications network. 
A. logical network perimeter    B. trust boundary
C. organizational  boundary     D. Overlapping boundary
2. Cloud storage device mechanisms provide common logical units of data storage, such as:     D    
A. files and blocks   B. datasets   C. object   D. all
3. Resource replication     D    .
A. is defined as the creation of multiple instances of the same IT resource
B. is typically performed when an IT resource’s availability and performance need to be enhanced.
C. is implemented by virtualization technology to replicate cloud-based IT resources.
D.all
4. Typical ready-made environments include pre-installed IT resources, such as    D      .
A. databases  B. middleware  C. development and governance tools   D. all
5. A      A     is an intermediary, event-driven program that exists as a service agent and resides along existing communication paths to transparently monitor and analyze dataflows.
A. monitoring agent      B. resource agent    C. polling agent     D. usage agent
6.     A     are used by cloud providers to share the same physical server with multiple cloud consumers by providing cloud consumers with individual virtual server instances.
A. Virtual servers   B.Hypervisors    C.VIMs    D. All
7. The ready-made environment mechanism is a defining component of the    B      cloud delivery model.
A. IaaS    B. PaaS    C. SaaS   D.all
8. The primary motivation for using non-relational storage is to avoid the     D     that can be imposed by relational databases.
A. potential complexity        B. processing overhead
C. more horizontally scalable    D.A and B
9. The number of virtual server instances is limited by  A      .
A. the capacity of given physical server  B. Hypervisors 
C. the number of cloud consumers        D.VIM
10. Cloud usage monitors can exist in different formats.    C      is not belong them.
A. monitoring agent      B. resource agent    C. usage agent   D. polling agent