Cloud Computing (IaaS,PaaS and SaaS)
What is 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.
IaaS how it works?
In an IaaS model, a cloud provider hosts the infrastructure components traditionally present in an on-premises data center, including servers, storage and networking hardware, as well as the virtualization or hypervisor layer.
The IaaS provider also supplies a range of services to accompany those infrastructure components. These can include detailed billing, monitoring, log access, security, load balancing and clustering, as well as storage resiliency, such as backup, replication and recovery. These services are increasingly policy-driven, enabling IaaS users to implement greater levels of automation and orchestration for important infrastructure tasks. For example, a user can implement policies to drive load balancing to maintain application availability and performance.
IaaS customers access resources and services through a wide area network (WAN), such as the internet, and can use the cloud provider's services to install the remaining elements of an application stack. For example, the user can log in to the IaaS platform to create virtual machines (VMs); install operating systems in each VM; deploy middleware, such as databases; create storage buckets for workloads and backups; and install the enterprise workload into that VM. Customers can then use the provider's services to track costs, monitor performance, balance network traffic, troubleshoot application issues and manage disaster recovery and more.
Any cloud computing model requires the participation of a provider. The provider is often a third-party organization that specializes in selling IaaS. Amazon Web Services (AWS) and Oracle Cloud Infrastructure (OCI) are examples of independent IaaS providers. A business might also opt to deploy a private cloud, becoming its own provider of infrastructure services.
IaaS pros and cons
Organizations choose IaaS because it is often easier, faster and more cost-efficient to operate a workload without having to buy, manage and support the underlying infrastructure. With IaaS, a business can simply rent or lease that infrastructure from another business.
IaaS is an effective model for workloads that are temporary, experimental or that change unexpectedly. For example, if a business is developing a new software product, it might be more cost-effective to host and test the application using an IaaS provider. Once the new software is tested and refined, the business can remove it from the IaaS environment for a more traditional, in-house deployment. Conversely, the business could commit that piece of software to a long-term IaaS deployment, where the costs of a long-term commitment may be less.
In general, IaaS customers pay on a per use basis, typically by the hour, week or month. Some IaaS providers also charge customers based on the amount of virtual machine space they use. This pay-as-you-go model eliminates the capital expense of deploying in-house hardware and software.
Service Providers: Amazon Web Services (AWS), Oracle Cloud Infrastructure (OCI) and Google Compute Engine (GCE) etc..
What is PaaS (Platform as a Service)
PaaS or platform as a service model provides computing platforms which typically includes 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 platform.
PaaS how it works?
PaaS does not typically replace a business's entire IT infrastructure. Instead, a business relies on PaaS providers for key services, such as application/Database hosting or Java development.
A PaaS provider builds and supplies a resilient and optimized environment on which users can install applications and data sets. Users can focus on creating and running applications rather than constructing and maintaining the underlying infrastructure and services.
Many PaaS products are geared toward software development. These platforms offer compute and storage infrastructure, as well as text editing, version management, compiling and testing services that help developers create new software more quickly and efficiently. A PaaS product can also enable development teams to collaborate and work together, regardless of their physical location.
PaaS pros and cons
The principal benefit of PaaS is simplicity and convenience for users. PaaS provider supplies much of the infrastructure and other IT services, which users can access anywhere via a web browser. PaaS providers then charge for that access on a per-use basis. A model that many enterprises prefer, as it eliminates the capital expenses they traditionally have for on-premises hardware and software. Some PaaS providers charge a flat monthly fee to access their service, as well as the apps hosted within it.
Service availability or resilience, however, can be a concern with PaaS. If a provider experiences a service outage or other infrastructure disruption, this can adversely affect customers and result in costly lapses of productivity. Provider lock-in is another common concern, since users cannot easily migrate many of the services and much of the data produced through one PaaS product to another competing product. Users must evaluate the business risks of service downtime and lock-in before they commit to a PaaS provider.
Internal changes to a PaaS product are also a potential issue. For example, if a PaaS provider stops supporting a certain programming language or opts to use a different set of development tools, the impact on users can be difficult and disruptive. Users must follow the PaaS provider's service roadmap to understand how the provider's plans will affect its environment and capabilities.
Service Providers: Force.com, Windows Azure, Oracle Corporation etc..
What is 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.
Software as a service (SaaS) is a software distribution model in which a third-party provider hosts applications and makes them available to customers over the Internet. SaaS is one of three main categories of cloud computing, alongside infrastructure as a service (IaaS) and platform as a service (PaaS).
SaaS removes the need for organizations to install and run applications on their own computers or in their own data centers. This eliminates the expense of hardware acquisition, provisioning and maintenance, as well as software licensing, installation and support. Other benefits of the SaaS model include:
Flexible payments: Rather than purchasing software to install, or additional hardware to support it, customers subscribe to a SaaS offering. Generally, they pay for this service on a monthly basis using a pay-as-you-go model. Transitioning costs to a recurring operating expense allows many businesses to exercise better and more predictable budgeting. Users can also terminate SaaS offerings at any time to stop those recurring costs.
Scalable usage: Cloud services like SaaS offer high scalability, which gives customers the option to access more, or fewer, services or features on-demand.
Automatic updates: Rather than purchasing new software, customers can rely on a SaaS provider to automatically perform updates and patch management. This further reduces the burden on in-house IT staff.
Accessibility and persistence: Since SaaS applications are delivered over the Internet, users can access them from any Internet-enabled device and location.
PaaS pros and cons
But SaaS also poses some potential disadvantages. Businesses must rely on outside vendors to provide the software, keep that software up and running, track and report accurate billing and facilitate a secure environment for the business' data. Providers that experience service disruptions, impose unwanted changes to service offerings, experience a security breach or any other issue can have a profound effect on the customers' ability to use those SaaS offerings. As a result, users should understand their SaaS provider's service-level agreement, and make sure it is enforced.
SaaS is closely related to the ASP (application service provider) and on demand computing software delivery models. The hosted application management model of SaaS is similar to ASP: the provider hosts the customer’s software and delivers it to approved end users over the internet. In the software on demand SaaS model, the provider gives customers network-based access to a single copy of an application that the provider created specifically for SaaS distribution. The application’s source code is the same for all customers and when new features are functionalities are rolled out, they are rolled out to all customers. Depending upon the service level agreement (SLA), the customer’s data for each model may be stored locally, in the cloud or both locally and in the cloud.
There are SaaS applications for fundamental business technologies, such as email, sales management, customer relationship management (CRM), financial management, human resource management, billing and collaboration. Leading SaaS providers include Salesforce, Oracle, SAP, Intuit and Microsoft.
Service Providers: Google Apps, Microsoft office365, Salesforce etc..
