Platform as a service

Platform as a service (PaaS) is a category of cloud computing services that provide a computing platform and a solution stack as a service. In the classic layered model of cloud computing, the PaaS layer lies between the SaaS and the IaaS layers.

PaaS offerings facilitate the deployment of applications without the cost and complexity of buying and managing the underlying hardware and software and provisioning hosting capabilities, providing all of the facilities required to support the complete life cycle of building and delivering web applications and services entirely available from the Internet.

Various types of PaaS vendor offerings could be extensive and will include a total application hosting, development, testing, and deployment environment, along with extensive integrated services that consist of scalability, maintenance, and versioning.

PaaS offerings may include facilities for application design, application development, testing, deployment and hosting as well as application services such as team collaboration, web service integration and marshalling, database integration, security, scalability, storage, persistence, state management, application versioning, application instrumentation and developer community facilitation. These services may be provisioned as an integrated solution over the web.^{[citation needed]}

Types

Add-on development facilities

These facilities allow customization of existing software-as-a-service (SaaS) applications, and in some ways are the equivalent of macro language customization facilities provided with packaged software applications such as Lotus Notes, or Microsoft Word. Often these require PaaS developers and their users to purchase subscriptions to the co-resident SaaS application.^{[citation needed]}

Stand alone development environments

Stand-alone PaaS environments do not include technical, licensing or financial dependencies on specific SaaS applications or web services, and are intended to provide a generalized development environment.^{[citation needed]}

Application delivery-only environments

Some PaaS offerings lack development, debugging and test capabilities, and provide only hosting-level services such as security and on-demand scalability.^{[citation needed]}

Open platform as a service

Lets the developer use any programming language, any database, any operating system, any server, etc.

Key characteristics

Services to develop, test, deploy, host and maintain applications in the same integrated development environment

Different PaaS offerings provide different combinations of services to support the application development life-cycle. Comprehensive PaaS should provide all service options in an integrated development environment within the actual target delivery platform, with source code control, version control, dynamic (interactive) multiple user testing, roll out and roll back with the ability to audit and track who made what changes when to accomplish what purpose^{[citation needed]}

Web based user interface creation tools

PaaS offerings typically provide some level of support to ease the creation of user interfaces, either based on standards such as HTML and JavaScript or other Rich Internet Application technologies like Adobe Flex, Flash and AIR. Rich, interactive, multi-user environments and scenarios can be defined, tried out by real people (non-programmers), with tools that make it easy to log/single out features that annoy or frustrate either novices or experts. Creation tools allow interfaces to be defined for different user profiles by function or expertise. PaaS offers improved user experience by incorporating channels for real people feedback throughout creation, design, development, testing, roll-out, production...the entire life-cycle through to 'end-of-life" "reincarnation" or "next generation evolution" of the application.^{[citation needed]}

Multi-tenant architecture

PaaS offerings typically attempt to support use of the application by many concurrent users, by providing concurrency management, scalability, fail-over and security. The architecture enables defining the "trust relationship" between users in security, access, distribution of source code, navigation history, user (people and device) profiles, interaction history, and application usage.^{[citation needed]}

Integration with web services and databases

Support for SOAP and REST interfaces allow PaaS offerings to create compositions of multiple web services, sometimes called "mashups" as well as access databases and re-use services maintained inside private networks. Support for keeping the user/relationships (if multiple users)/device context and profile through the mashup across web services, databases and networks.^{[citation needed]}

Support for development team collaboration

The ability to form and share code with ad-hoc or pre-defined or distributed teams greatly enhances the productivity of PaaS offerings. Schedules, objectives, teams, action items, owners of different areas of responsibilities, roles (designers, developers, tester, QC) can be defined, updated and tracked based on access rights.^{[citation needed]}

Utility-grade instrumentation

PaaS offerings provide developers insight into the inner workings of their applications, and the behavior of their users. Some PaaS offerings use information about user behaviour to enable pay-per-use billing. Historical/usage evidence may help:^{[citation needed]}

• determine whether services are of value to users/customers,
• compare the value of different services, and
• track activity based costs and revenues.

Visualization tools could show usage patterns, exposing functional or correlational relationships between:^{[citation needed]}

• services and/or user interactions,
• the value to the user or users, and
• the cost of alternative service paths such as web and cell phone

Financial data collection and, possibly, forecasting, are required to determine who pays what to whom and when (how often).^{[citation needed]}

See also

• Cloud computing
• Software as a service
• Infrastructure as a service
• IT as a Service

External links

• Google App Engine
• Heroku
• Windows Azure
• Red Hat OpenShift
• Engine Yard
• Hammerkit

External links

• The Ever-Growing List of PaaS Companies and PaaS Projects
• European Project 4CaaSt - Building the PaaS Cloud of the Future; funded by the EU 7th Framework Programme Internet of Services, Software and Virtualisation.
• ConPaaS - integrated runtime environment for elastic Cloud applications; funded by the EU 7th Framework Programme in the context of the Contrail project.