Platform as a Service (PaaS) is a cloud model designed for software developers that streamlines the development process by shifting specific aspects of systems management to the service provider. PaaS is used to develop web and mobile applications using components that are pre-configured and maintained by the service provider, including programming languages, application servers and databases.
Today I will list some popular PAAS vendors for your reference.
BlueMix is an implementation of IBM’s Open Cloud Architecture, leveraging Cloud Foundry to enable developers to rapidly build, deploy, and manage their cloud applications, while tapping a growing ecosystem of available services and runtime frameworks. IBM will provide services and runtimes into the ecosystem based on our extensive software portfolio.It offically support Liberty for Java™,Node.js,Ruby on Rails,Ruby Sinatra.Since itis built on top of Cloud Foundry and you can add support for languages or frameworks not supported in Cloud Foundry by default.Now it is in beta
Heroku was acquired by Salesforce.com in 2010. one of the first cloud platforms, has been in development since June 2007, when it supported only the Ruby programming language, but has since added support for Java, Node.js, Scala, Clojure and Python and (undocumented) PHP and Perl. The base operating system is Debian or, in the newest stack, the Debian-based UbuntuHeroku is the leading platform as a service in the world and supports Ruby, Java, Python, Scala, Clojure, and Node.js. Deploying an app is simple and easy.
Red Hat OpenShift
Red Hat OpenShift is based on open source applications and offers a wide variety of languages, databases and components. The PaaS is highly customizable and offered in three forms: OpenShift Online (a cloud-based hosting service), OpenShift Enterprise (a private PaaS that runs in your data center) and OpenShift Origin (the open source application hosting platform). OpenShift automates system administration tasks such as virtual server provisioning, configuration and scaling and supports git repositories for code management.
Google App Engine
Google App Engine is designed for distributed web applications and developers using Java, Python, PHP and Go. The Java environment supports other languages that make use of the JRE and there is a SDK for each of the four main supported languages as well as a plugin for Eclipse. The PaaS offers managed infrastructure and runtime environments that are guaranteed to scale, but only if the applications fit the restrictions of Google App Engine. The Datastore, a transactional, schema-less data store based on key-value pairs, handles the complex management of data that's accessible to multiple machine instances. Programming languages are limited to Java, Python, Go and PHP.
AppFog is a multi-language, multi-framework PaaS that's a good option for multi-cloud deployments, including private clouds. AppFog supports Java, Ruby, PHP, Python, Node, Scala and Erlang and offers MySQL, PostgreSQL, Redis and RabbitMQ along with third party add-on services. It can be used as a DaaS with ClearDB, MongoHQ, MongoLab, Redis Cloud and Xeround. AppFog is based on the open source Cloud Foundry platform and supports Git, SVN and Mercurial for code management.
Windows Azure Cloud Services
Within Windows Azure, Microsoft is blurring the lines between IaaS and PaaS. Windows Azure Cloud Services supports .NET, Node.js, PHP, Python, Java and Ruby. In addition to software development kits, developers can use Visual Studio for creating and deploying applications. Developers can choose between a SQL Database, Tables and Blobs when it comes to persistent storage. Applications are administered through the Windows Azure dashboard or through a command line interface.
Although Amazon Web Services is primarily an IaaS, many of the services available in AWS are comparable to PaaS offerings. You can use the platform services available in AWS without having to create or maintain your own application servers. AWS readily supports Java, Python, Ruby, Perl and other languages. Oracle, MySQL and SQL Server can be set up and managed, but AWS offers RDS web service as well, which eliminates database administration tasks. Developers can take advantage of Amazon Elastic Beanstalk for automatic load balancing, auto-scaling, and application health monitoring
Force.com is a Platform as a Service (PaaS) product designed to simplify the development and deployment of cloud-based applications and websites. Developers can create apps and websites through the cloud IDE (integrated development environment) and deploy them quickly to Force.com’s multi-tenant servers.
Also there is a good site http://www.paasify.it/vendors ,you can choose your PAAS based on the predefined search condition.