本篇文章是对课程大型软件系统设计与体系结构(双语)【又名：云计算】的课堂内容总结，适用于大连交通大学。

Cloud Computing Chapter3

Understanding Cloud Computing(理解云计算)

3.1 origins and Influences（起源和影响）

--A Brief History

1961,computer scientist John McCarthy publicly proposed utility computing（效用计算）

1969 ARPANET project “spread of computer utilities”

Mid-1990s google, email,facebook,

Late 1990s salesforce.com remotely provisioned service

2002 Amazon web services platform

2006 - the term cloud computing(云计算 )emerged in the commercial arena.

Amazon launched its Elastic Compute Cloud（弹性云计算） (EC2) services that enabled organizations to “lease” (租赁)computing capacity and processing power to run their enterprise applications.

Google Apps also began providing browser-based enterprise applications in the same year, and three years later, the Google App Engine became another historic milestone.

Definitions

-- Gartner(1):

a style of computing in which scalable and elastic IT-enabled capabilities are delivered as a service to external customers using Internet technologies.

--Forrester(2) :

a standardized IT capability (services, software, or infrastructure) delivered via Internet technologies in a pay-per-use, self-service way.

--NIST (3):

Cloud computing is a model for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction.

--This book (4):

Cloud computing is a specialized form of distributed computing that introduces utilization models for remotely provisioning scalable and measured resources.

Business Drivers 商业驱动力

--Capacity Planning 容量规划：

• the process of determining and fulfilling future demands of an organization's IT resources, products, and services.

• capacity planning strategies:

1.Lead Strategy – adding capacity to an IT resource in anticipation of demand

2.Lag Strategy – adding capacity when the IT resource reaches its full capacity

3.Match Strategy – adding IT resource capacity in small increments, as demand increases

--Cost Reduction 降低成本

--Organizational Agility 组织灵活性

Technology Innovations 技术创新

--Clustering 集群化

a group of independent IT resources that are interconnected and work as a single system. System failure rates are reduced while availability and reliability are increased, since redundancy and failover features are inherent to the cluster.

--Grid Computing 网格计算

provides a platform in which computing resources are organized into one or more logical pools.

--Virtualization 虚拟化

a technology platform used for the creation of virtual instances of IT resources.

-Technology Innovations vs. Enabling Technologies

计算创新和使能技术

3.2 Basic Concepts and Terminology

Cloud

--A cloud refers to a distinct IT environment that is designed for the purpose of remotely provisioning scalable and measured IT resources.

--Symbol

Figure 3-1

IT Resource

--An IT resource is a physical or virtual IT-related artifact that can be either software-based, such as a virtual server or a custom software program, or hardware-based, such as a physical server or a network device .

(Figure 3-2)

Figure 3-3:冰山一角

On-Premise 企业内部的

---------An IT resource that is on-premise cannot be cloud-based

---An on-premise IT resource can access and interact with a cloud-based IT resource.

--An on-premise IT resource can be moved to a cloud, thereby changing it to a cloud-based IT resource.

--Redundant deployments of an IT resource can exist in both on-premise and cloud-based environments

Cloud Consumers and Cloud Providers

--cloud provider 云提供者

The party that provides cloud-based IT resources

--cloud consumer 云用户

The party that uses cloud-based IT resources

Scaling 可扩展性

--Horizontal Scaling 水平扩展

--Vertical Scaling 垂直扩展

--Horizontal Scaling

－scaling out 向外扩展

－scaling in 向内扩展

Figure 3-4

--Vertical Scaling

－scaling up 向上扩展

－scaling down 向下扩展

Figure 3-5

Cloud Service 云服务

--A cloud service is any IT resource that is made remotely accessible via a cloud.

Figure 3-6

The driving motivation behind cloud computing is to provide IT resources as services that encapsulate other IT resources

--remotely.

--as-a-service

--a service-level agreement (SLA)

Cloud Service Consumer 云服务用户

--a temporary runtime role assumed by a software program when it accesses a cloud service

Figure 3-7

3.3. Goals and Benefits 目标和收益

Reduced Investments and Proportional Costs(降低的投资与成比例的开销)

--Common measurable benefits to cloud consumers include:

On-demand access to pay-as-you-go computing resources

The perception of having unlimited computing resources

The ability to add or remove IT resources at a fine-grained level

Abstraction of the infrastructure

Increased Scalability (提高的可扩展性)

--Cloud consumers can scale or release their cloud-based IT resources automatically or manually.

--To provide flexible levels of scalability to IT resources is the inherent, built-in feature of clouds

Figure 3-8

Increased Availability and Reliability(提高的可用性和可靠性)

--An IT resource with increased availability is accessible for longer periods of time (for example, 22 hours out of a 24 hour day). Cloud providers generally offer “resilient” IT resources for which they are able to guarantee high levels of availability.

--An IT resource with increased reliability is able to better avoid and recover from exception conditions. The modular architecture of cloud environments provides extensive failover support that increases reliability

3.4. Risks and Challenges风险与挑战

--Increased Security Vulnerabilities

增加的安全漏洞

Figure 3-9

--Reduced Operational Governance Control

降低的运营管理控制

Figure 3-10

--Limited Portability Between Cloud Providers

云提供者之间有限的可移植性

summary

--cloud computing 云计算

--cloud 云

--IT resource IT资源

--on-premise 企业内部的

--cloud consumer 云用户

--cloud provider 云提供者

-- horizontal scaling 水平扩展

--vertical scaling 垂直扩展

--cloud service 云服务

-- cloud service consumer 云服务用户

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