什么是 SaaS、PaaS 和 IaaS？ 举例

Question

What do the following terms mean?

• SaaS
• PaaS
• IaaS?

There are various cloud services available today, such as Amazon's EC2 and AWS, Apache Hadoop, Microsoft Azure and many others. Which category does each belong to and why?

Answer 1

IaaS, PaaS and SaaS are cloud computing service models.

• IaaS (Infrastructure as a Service), as the name suggests, provides you the computing infrastructure, physical or (quite often) virtual machines and other resources like virtual-machine disk image library, block and file-based storage, firewalls, load balancers, IP addresses, virtual local area networks etc.

  Examples: Amazon EC2, Windows Azure, Rackspace, Google Compute Engine.

• PaaS (Platform as a Service), as the name suggests, provides you computing platforms which typically includes operating system, programming language execution environment, database, web server etc.

  Examples: AWS Elastic Beanstalk, Windows Azure, Heroku, Force.com, Google App Engine, Apache Stratos.

• While in SaaS (Software as a Service) model you are provided with access to application software often referred to as "on-demand software". You don't have to worry about the installation, setup and running of the application. Service provider will do that for you. You just have to pay and use it through some client.

  Examples: Google Apps, Microsoft Office 365.

Few additional points regarding your question:

1. AWS (Amazon web services) is a complete suite which involves a whole bunch of useful web services. Most popular are EC2 and S3 and they belong to IaaS service model.

2. Although Hadoop is based on previous works by Google(GFS and MapReduce), it is not from Google. It is an Apache project. You can find more here . It is just a distributed computing platform and does not fall into any of these service models, IMHO.

3. Microsoft's Windows Azure is again an example of IaaS.

As far as popularity of these services is concerned, they all are popular. It's just that which one fits into your requirements better. For example, if you want to have a Hadoop cluster on which you would run MapReduce jobs, you will find EC2 a perfect fit, which is IaaS. On the other hand if you have some application, written in some language, and you want to deploy it over the cloud, you would choose something like Heroku, which is an example of PaaS.

Answer 2

Meaning For dummies:

IAAS (Infrastructure As A Service) :

• The base layer

• Deals with Virtual Machines, Storage (Hard Disks), Servers, Network, Load Balancers etc

PAAS (Platform As A Service) :

• A layer on top of IAAS

• Runtimes (like java runtimes), Databases (like mySql, Oracle), Web Servers (tomcat etc)

SAAS (Software As A Service) :

• A layer on top on PAAS

• Applications like email (Gmail, Yahoo mail etc), Social Networking sites (Facebook etc)

To quickly relate consider the below Google's offerings:

IAAS : Google Compute Engine (One can develop programs to be run on high performing google's computing infrastructure)

PAAS : Google App Engine (One can develop applications and let them execute on top of Google app engine which take care of the execution)

SAAS : Gmail, Google+ etc (One can use email services and extend email/google+ based applications to form newer applications)

Popularity

Company Wise Popularity

Cloud computing is dominated by

1. Amazon Web Services (AWS),
2. Google Compute Engine, Google App Engine
3. Microsoft Azure
4. There are many small and medium scale cloud operators that include IBM, Oracle etc.

Most of the popularity around these services owe to the reputation of the company and the amount of investments being made by these companies around the cloud space.

Type of Service Wise Popularity

1. PAAS (Platform as a Service) is more popular among developers as they can put all their concentration on developing their apps and leave the rest of management and execution to the service provider. Many service providers also offer the flexibility to increase/decrease the CPU power depending upon the traffic loads giving developers cost effective and easy & effortless management.
2. SAAS (Software as a service) is more popular among with consumers, who bother about using the application such as email, social networking etc
3. IAAS (Infrastructure as a service) is more popular among users into research and high computing areas.

Answer 3

When you are a simple client who wants to make use of a software but you have nothing in hand then you use SaaS .

When you have a software developed by you, but you want to deploy and run on a publicly available platform then you use PaaS .

When you have the software and the platform ready but you want the hardware to run then you use IaaS .

Answer 4

Difference between IaaS PaaS & SaaS

In the following tabular format we will be explaining the difference in context of

  pizza as a service 

Answer 5

There are three major types of cloud services: IaaS, PaaS, and SaaS . You've probably seen these abbreviations on the websites of cloud providers. Before going into details, let's compare IaaS, PaaS, and SaaS to transportation :

1. On-premises IT infrastructure is like owning a car. When you buy a car, you're responsible for its maintenance, and upgrading means buying a new car.

2. IaaS is like leasing a car. When you lease a car, you choose the car you want and drive it wherever you wish, but the car isn't yours. Want an upgrade? Just lease a different car!

3. PaaS is like taking a taxi. You don't drive a taxi yourself, but simply tell the driver where you need to go and relax in the back seat.

4. SaaS is like going by bus. Buses have assigned routes, and you share the ride with other passengers.

Reference: https://rubygarage.org/blog/iaas-vs-paas-vs-saas

Answer 6

IaaS (Infra as a Service)

IaaS provides the infrastructure such as virtual machines and other resources like virtual-machine disk image library, block and file-based storage, firewalls, load balancers, IP addresses, virtual local area networks etc. Infrastructure as service or IaaS is the basic layer in cloud computing model.

Common examples: DigitalOcean, Linode, Rackspace, Amazon Web Services (AWS), Cisco Metapod, Microsoft Azure, Google Compute Engine (GCE) are some popular examples of Iaas.

PaaS (Platform as a Service)

PaaS or platform as a service model provides you computing platforms which typically includes an operating system, programming language execution environment, database, web server. technically It is a layer on top of IaaS as the second thing you demand after Infrastructure is a platform.

Common examples: AWS Elastic Beanstalk, Windows Azure, Heroku, Force.com, Google App Engine, Apache Stratos.

SaaS (Software as a Service)

In a SaaS, you are provided access to application services installed at a server. You don't have to worry about installation, maintenance or coding of that software. You can access and operate the software with just your browser. You don't have to download or install any kind of setup or OS, the software is just available for you to access and operate. The software maintenance or setup or help will be provided by SaaS provider company and you will only have to pay for your usage.

Common examples: Google Apps, Microsoft office365, Google docs, Gmail, WHMCS billing software

Basic difference between IaaS, PaaS & SaaS

Answer 7

SaaS: Software as a Service Cloud application services or “Software as a Service” (SaaS) are probably the most popular form of cloud computing and are easy to use. SaaS uses the Web to deliver applications that are managed by a third-party vendor and whose interface is accessed on the clients' side. Most SaaS applications can be run directly from a Web browser, without any downloads or installations required. SaaS eliminates the need to install and run applications on individual computers. With SaaS, it's easy for enterprises to streamline their maintenance and support, because everything can be managed by vendors: applications, runtime, data, middleware, O/S, virtualization, servers, storage, and networking. Gmail is one famous example of an SaaS mail provider.

PaaS: Platform as a Service The most complex of the three, cloud platform services or “Platform as a Service” (PaaS) deliver computational resources through a platform. What developers gain with PaaS is a framework they can build upon to develop or customize applications. PaaS makes the development, testing, and deployment of applications quick, simple, and cost-effective, eliminating the need to buy the underlying layers of hardware and software. One comparison between SaaS vs. PaaS has to do with what aspects must be managed by users, rather than providers: With PaaS, vendors still manage runtime, middleware, O/S, virtualization, servers, storage, and networking, but users manage applications and data.

IaaS: Infrastructure as a Service Cloud infrastructure services, known as “Infrastructure as a Service” (IaaS), deliver computer infrastructure (such as a platform virtualization environment), storage, and networking. Instead of having to purchase software, servers, or network equipment, users can buy these as a fully outsourced service that is usually billed according to the amount of resources consumed. Basically, in exchange for a rental fee, a third party allows you to install a virtual server on their IT infrastructure. Compared to SaaS and PaaS, IaaS users are responsible for managing more: applications, data, runtime, middleware, and O/S. Vendors still manage virtualization, servers, hard drives, storage, and networking. What users gain with IaaS is infrastructure on top of which they can install any required platforms. Users are responsible for updating these if new versions are released.

Answer 8

IaaS, PaaS and SaaS are basically cloud computing segment.

IaaS (Infrastructure as a Service) - Infrastructure as a Service is a provision model of cloud computing in which an organization outsources the equipment used to support operations, including storage, hardware, servers and networking components. The service provider owns the equipment and is responsible for housing, running and maintaining it. The client typically pays on a per-use basis. Ex- Amazon Web Services , BlueLock , Cloudscaling and Datapipe

PaaS (Platform as a Service) - Platform as a Service is one of the GROWING sector of cloud computing. PaaS basically help developer to speed the development of app, saving money and most important innovating their applications and business instead of setting up configurations and managing things like servers and databases. In one line I can say Platform as a service (PaaS) automates the configuration, deployment and ongoing management of applications in the cloud. Ex: Heroku , EngineYard , App42 PaaS and OpenShift

SaaS (Software as a Service) - Software as a Service, SaaS is a software delivery method that provides access to software and its functions remotely as a Web-based service. Ex: Abiquo's and Akamai

Answer 9

Adding to that, I have used AWS, heroku and currently using Jelastic and found -

Jelastic offers a Java and PHP cloud hosting platform. Jelastic automatically scales Java and PHP applications and allocates server resources, thus delivering true next-generation Java and PHP cloud computing. http://blog.jelastic.com/2013/04/16/elastic-beanstalk-vs-jelastic/ or http://cloud.dzone.com/articles/jelastic-vs-heroku-1

Personally I found -

• Jelastic is faster
• You don't need to code to any jelastic APIs – just upload your application and select your stack. You can also mix and match software stacks at will.

Try any of them and explore yourself. Its fun :-)

Answer 10

There are three major categories of cloud service models:

• Software as a service (SaaS)
• Platform as a service (PaaS)
• Infrastructure as a service (IaaS)

Software as a service (SaaS)

SaaS is a software that is centrally hosted and managed for the end customer. It's usually based on a multi-tenant architecture (a single version of the application is used for all customers) and typically is licensed through a monthly or annual subscription.

Example Office 365, Dropbox, Dynamics CRM Online are perfect examples of SaaS software, subscribers pay a monthly or annual subscription fee, and they get Exchange as a Service (online and/or desktop Outlook) or Storage as a Service (OneDrive and Dropbox).

Platform as a service (PaaS)

With PaaS, you deploy your application into an application-hosting environment (designed for building, testing, and deploying software applications) provided by the cloud service vendor. Developers have multiple ways to deploy their applications without knowing anything about what's happening in the background to supporting it.

Example Web Apps feature in Azure App Service and Azure Cloud Services (web and worker roles) are an example of PaaS.

Infrastructure as a service (IaaS)

An IaaS cloud vendor runs and manages server farms running virtualization software, enabling you to create VMs (running Windows or Linux) that run on the vendor's infrastructure and install anything you want on it. Developers don't have control over the hardware or virtualization software, but they have control over almost everything else. In fact, unlike PaaS, you are completely responsible for it.

References

Book : Architecting the Cloud: Design Decisions for Cloud Computing Service Models (SaaS, PaaS, and IaaS)

Answer 11

Here is another take with AWS Example of each service:

IaaS (Infrastructure as a Service): You get the whole infrastructure with hardware. You chose the type of OS that needs to be installed. You will have to install the necessary software.

AWS Example: EC2 which has only the hardware and you select the base OS to be installed. If you want to install Hadoop on that you have to do it yourself, it's just the base infrastructure AWS has provided.

PaaS (Platform as a Service): Provides you the infrastructure with OS and necessary base software. You will have to run your scripts to get the desired output.

AWS Example: EMR Which has the hardware (EC2) + Base OS + Hadoop software already installed. You will have to run hive/spark scripts to query tables and get results. You will need to invoke the instance and wait for 10 min for the setup to be ready. You have to take care of how many clusters you need based on the jobs you are running, but not worry about the cluster configuration.

SaaS (Software as a Service): You don't have to worry about Hardware or even Software. Everything will be installed and available for you to use instantly.

AWS Example: Athena, which is just a UI for you to query tables in S3 (with metadata stored in Glu). Just open the browser login to AWS and start running your queries, no worry about RAM/Storage/CPU/number of clusters, everything the cloud takes care of.

Answer 12

I know this question has been answered a while ago but this could help.

What do the following terms mean?

SaaS

Software as a Service - Essentially, any application that runs with its contents from the cloud is referred to as Software as a Service, As long as you do not own it.

Some examples are Gmail, Netflix, OneDrive etc.

AUDIENCE : End users, everybody

IaaS

Infrastructure as a Service means that the provider allows a portion of their computing power to its customers, It is purchased by the potency of the computing power and they are bundled in Virtual Machines. A company like Google Cloud platform, AWS, Alibaba Cloud can be referred to as IaaS providers because they sell processing powers (servers, storage, networking) to their users in terms of Virtual Machines.

AUDIENCE : IT professionals, System Admins

PaaS

Platform as a Service is more like the middle-man between IaaS and SaaS, Instead of a customer having to deal with the nitty-gritty of servers, networks and storage, everything is readily available by the PaaS providers. Essentially a development environment is initialized to make building applications easier.

Examples would be Heroku, AWS Elastic Beanstalk, Google App Engine etc

AUDIENCE : Software developers.

There are various cloud services available today, such as Amazon's EC2 and AWS, Apache Hadoop, Microsoft Azure and many others. Which category does each belong to and why?

Amazon EC2 and AWS - is an Infrastructure as a Service because you'll need System Administrators to manage the working process of your operating system. There is no abstraction to build a fully featured app ordinarily. Microsoft Azure would also fall under this category following the aforementioned guidelines.

I really haven't used Apache Hadoop, so I really cannot say.

Answer 13

Following link gives very good explanation on SaaS, PaaS and Iaas.. http://opensourceforgeeks.blogspot.in/2015/01/difference-between-saas-paas-and-iaas.html

Just some brief:

---

IaaS , here vendor provides infra to user where an user gets hardware/virtualization infra, storage and Networking infra.

PaaS , here vendor provides platform to user where an user gets all required things for their work like OS, Database, Execution Environment along with IaaS provided environment. So pass is platform + IaaS.

SaaS seems to be quite wide area where vendor provides almost everything from infra to platform to software. So SaaS is Iaas+PaaS along with different softwares like ms office, virtual box etc..

Answer 14

Iam sharing my experiences along with Standard definitions by NIST. Iam developer from product company and we own database and client (eco system). Beside many clear pictures the confusion arises because of many actors(5 defined by NIST) and things differ from prespectives.

For IaaS and Bare metal deployments we sell licenses and packages can be obtained from CD's or FTP server (rpms). The code is compiled tested and delivered. Here our customers pay to us (license cost) and/or to cloud provider for instances.

We partner with cloud providers (technology partner) to sell our products via marketplace.

Typically we deliver images (ami,vhd,etc) + some (cloud formation templates or ARM templates, etc) in case of PaaS . We have Jenkins pipelines to place them in market place (version based). Here with some skills developers can login into instances and manipulate the software (eg after database instances are launched login and completely remove the software and make it look like just EC2 instances)

In case of SaaS our Jenkins pipelines will directly deploy (whether they are web apps, azure/lambda functions). Neither developers/end users have less control over the physical hardware.

Below are the Actors defined by NIST and since developers(tech company that provides software) partners with cloud provider, developers best match is cloud provider.

Answer 15

The illustration below explains the difference between IaaS, CaaS and PaaS in simple words. Orange - you manage it, blue - you get it as a service. And with SaaS you even get data and application layers as a service as well.

Also, for those who are interested to learn more about PaaS combinations the following article What is Platform-as-a-Service? Types Explained can be helpful.

Answer 16

As all have explained very well about the Cloud computing models. So I want to picture out all three model IaaS , PaaS , SaaS wrt AWS services and their consumers.

Answer 17

Since there are a lot of answers with better definitions of the question. I would like to add a few examples here:

IaaS

• AWS EC2
• Rackspace
• Google Compute Engine(GCE)
• Digital Ocean
• Magento 1 Enterprise Edition
• Oracle Cloud
• Vultr

PaaS

• AWS Elastic Beanstalk
• Heroku
• Windows Azure
• Force.com
• OpenShift
• Apache Stratos
• Magento Commerce Cloud

SaaS

• Google Apps
• Salesforce
• Dropbox
• MailChimp
• ZenDesk
• DocuSign
• Slack
• Hubspot
• Cisco
• WebEx
• Concur
• GoToMeeting

Answer 18

SaaS	PaaS	Iaas
Software-as-a-Service	Platform-as-a-Service	Infrastructure-as-a-Service
Ready to use infrastructure and software application that are centrally hosted and licensed on a subscription basis.	Ready to use environment. where customers build, test, run, and update apps quickly and inexpensively.	Provides on-demand access to physical computing resources, such as servers, storage, networking, and data center space without need to manage or operate.
Apps can be accessed over the internet on any device with a browser.	Cloud provider manages the entire platform.	Users can provision, test, and scale resources quickly.
Easy to add additional users and storage.	Additional compute, storage, and networking capacity can be purchased quickly and used immediately.	NA
Use Cases: Most personal or employee productivity applications (email, document management, online collaboration tools)	Use Cases: Migration of existing applications to the cloud, a hybrid cloud strategy	Use Cases: Backup/recovery of on-premises workloads, dev and test environments, customer facing websites, data storage and analytics