1. Understanding the PaaS service model

2. The Platform as a Service model provides the tools within an environment needed to create applications that can run in a Software as a Service model.
Some overlap between vendors has created Software as a Service products, and those vendors have broadened their services to make their Web applications more customizable.
Salesforce.com, the largest CRM application service company in the world, is an example, with Force.com being its PaaS (Platform as a Service) offering.

3. Defining Services
The Platform as a Service model is the most interesting of all the hosted services in cloud computing. IaaS offers a service that is equivalent to installing an application on a computer. That computer is virtual, of course, but it is still a computer.
By the time you are using an SaaS model, the software is pretty well mapped out for you. You can do some modest customization, some branding perhaps, but the software's capabilities and design has largely been worked out

4. With Platform as a Service systems, you are given a toolkit to work with, a virtual machine to run your
software on, and it is up to you to design the software and its user-facing interface in a way that is
appropriate to your needs.
So PaaS systems range from full-blown developer platforms like Windows Azure Platform to systems like Drupal, Squarespace, Wolf, and others where the tools are modules that are very well developed and require almost no coding

5. PaaS models span a broad range of services, including these, among others:
• Application development: A PaaS platform either provides the means to use programs you create in a supported language or offers a visual development environment that writes the code for you. • Collaboration: Many PaaS systems are set up to allow multiple individuals to work on the same projects. •Data management: Tools are provided for accessing and using data in a data store.

6. • Instrumentation, performance, and testing: Tools are available for measuring your applications
and optimizing their performance.
• Storage: Data can be stored in either the PaaS vendor's service or accessed from a third-party
storage service.
• Transaction management: Many PaaS systems provide services such as transaction managers or
brokerage service for maintaining transaction integrity.

7. PAAS desirable Characteristics
• Separate of data management from the user interface • Reliance on cloud computing standards • An integrated development environment (IDE) • Lifecycle management tools • Multi-tenant architecture support, security, and scalability • Performance monitoring, testing, and optimization tools

8. Salesforce.com versus Force.com: SaaS versus PaaS
Salesforce.com was formed by several Oracle employees in 1999 to create a hosted Customer Relationship Management (CRM) system. CRM has long been one of Oracle's core database services.
The Salesforce.com team created hosted software based on a cloud computing model: pay as you go, simple to use, and multifunctional. The Salesforce.com platform looks like a typical Web site such as Amazon.com, with a multi-tabbed interface—each tab being an individual application

9. Salesforce.com

10. Force.com

11. Using PaaS Application Frameworks
Application frameworks provide a means for creating SaaS hosted applications using a unified development environment or an integrated development environment (IDE).
PaaS IDEs run the gamut from a tool that requires a dedicated programming staff to create and run to point-and-click graphical interfaces that any knowledgeable computer user can navigate and create something useful with.

12. Example of CMS platform

13. What is Drupal? Open Source software written in php.
A CMS or content-management system.
A sophisticated web application building tool.

14. What is a CMS?
Simply put, a CMS is a website you build using the website itself.
Wikipedia definition: A content management system (CMS) such as a document management system (DMS) is a computer application used to manage work flow needed to collaboratively create, edit, review, index, search, publish and archive various kinds of digital media and electronic text.

15. What can Drupal be? blog Forum Online newspaper, Portal / Directory
portfolio, flickr like photo drop
Social community site, job post board
Video site like youtube
Project management site
CRM, ERP, Wiki
Shopping cart system
E-learning, training site
Anything you can think of…

16. Why use a CMS? It helps manage complexity.
It provides a user interface (UI) for adding, editing and publishing content.
It provides a means for collaboration among many to perform the above tasks.

17. Why use Drupal over Wordpress?
Wordpress was designed only to be a blog with some easy add-ons.
Drupal was designed to be more of a generalist: it’s for making ‘anything’ and is far more robust.
Wordpress could be the better choice for blogs since it is better at being a blog than Drupal. This is something of debate.
Wordpress is still a sound choice of CMS for SEO and security; so if wordpress satisfies a simpler project’s requirements then by all means use it- it is easier and faster to set up than Drupal.
Wordpress is not designed to be highly scalable to many simultaneous users, nor does it have flexible roles, permissions, extensible content types, nor does it have plentiful well-tested, quality add-ons. It has a few and a lot of really poor plugins.

18. Why use Drupal over Joomla? (or other CMS)
It has superior session handling for a CMS.
It has superior security.
It is a more consistent, reliable and flexible framework for development.
It is considered better for SEO from our research.
It uses a ‘separation of concerns’ architecture to cleanly and consistently separate structure, function, form, and presentation in layers (ie: php from data as db/xml, layout and presentation as html and css).
It heavily uses ‘defaults overrides’ in code in the form of hooks and in themes in the form of templates. This makes it extremely flexible.
Other CMS’es do a very very bad job of at least one of the above.

19. What is a UI?
UI is a user-interface, which is a general term for the layout of options, widgets and settings used to configure the system or manage content.
‘Site-building’ activities refer to configuring settings or managing content through the UI, such as building navigation menus.

20. Drupal Structure
Drupal is a database-driven (‘dynamic’) application. It requires a database.
Drupal has a core filesystem whose functionality can be extended using the UI itself, modules and themes.
The UI settings are stored in the database.

21. Modules
The Drupal core by itself contains a number of modules that provide for the following:
• Auto-updates
• Blogs, forums, polls, and RSS feeds
• Multiple site management
• OpenID authentication
• Performance optimization through caching and throttling
• Search
• User interface creation tools
• User-level access controls and profiles
• Themes
• Traffic management
• Workflow control with events and triggers