Which version of SharePoint?

SharePoint 2010 comes in many forms and there is now a bewildering array of ways in which you can develop your applications using "SharePoint" as a platform.  The following notes are intended to help you through the maze of options.

What is SharePoint?
First of all, the inevitable starting point - what is SharePoint?  In a nutshell, "SharePoint" is an application development environment oriented towards collaborative, web-based systems.  These systems feature regular user-interactions, workflows, and the storage of large volumes of documents and/or data records. 

You can use SharePoint out-of-the box if you are happy to accept the default look & feel.  You can develop complete applications, using standard features, or you can combine these with purchased components.  You can also develop your systems in a highly controlled and customised way, in code (in whole or part) using the SharePoint code libraries.  Having developed a system using SharePoint as a platform, that system can then only function where a compatible version of SharePoint exists.  That is to say, it is not free-standing.

SharePoint exists in many forms, although broadly speaking, each form is either implemented on a company's network or their private Internet server ("on-premise") or is hosted on a Microsoft server ("on-line", "in the cloud" or "SaaS").  There is a 3rd category actually, where SharePoint is hosted by a 3rd party on a multi-tenanted network.  This option is still a "cloud" option, although not Microsoft's cloud and the version of SharePoint being used is more likely to be one of the "on-premise" versions described below.

On-Premise SharePoint Environments
Traditionally, SharePoint was installed on company premises on a server and used to drive the company's Intranet (and sometimes Extranet).  This scenario is known as an "on-premise" solution.  The versions of SharePoint available for on-premise solutions are: Foundation, Standard and Enterprise (where Standard and Enterprise both assume the existence of Foundation).

SharePoint Foundation is analogous to Windows SharePoint Services at SharePoint 2003 and 2007, and provides the database and web-site creation "engine" on which everything else depends.  There are tools for creating applications, web site hierarchies, web sites, data lists and document libraries, web pages plus many surrounding sub-systems and features, such as workflow creation tools, page design facilities, navigation features, alerts and event triggers, database access, and many more facilities useful for application development.  SharePoint Foundation can be used as the basis for generating complete applications.  One might have to add 3rd party components or write some additional custom code to get the entire scope of functionality required, but it is possible to do so.  A particular area of weakness in Foundation is the search engine available, SharePoint Express, which is fine for getting started but may not be adequate for a sophisticated and demanding user base.

Development of SharePoint can be carried out in three ways.  The most straight-forward is to use a browser to access standard screen-based controls for generating artifacts using templates and out-of-the-box features.  There are limitations on what can be achieved via the browser, so the next level of development tool available is SharePoint Designer (SPD), a client tool for managing and developing SharePoint sites.  SPD is a sophisticated editor for power users and developers enabling low-level configuration of web sites and business applications.  Where absolute control over low-level design is required, and where it is necessary to extend the system with custom components, then Visual Studio is the tool used by programmers for this purpose.  The cost of development inevitably increases the lower you go and the more sophisticated and non-standard your requirements become.  Using ready-made components can be a cost-effective alternative in some cases.

SharePoint Standard is the first "paid-for" version of SharePoint server.  There are many payment structures to choose from depending on usage style and volume, but in its simplest form, SharePoint Standard is priced per SharePoint-user.  "Standard" adds to Foundation the following facilities: Enterprise Search, a sophisticated and capable search engine; analytics, many social networking features; tagging; "my Sites"; managed metadata and taxonomies; more data push and pull features and more list and document library types.  And there's more... (see the link following)

The Enterprise version of SharePoint Server is the top-of-the-range on-premise solution.  It comes with everything in Foundation and Standard, plus: Office client integration; business data and KPI analysis web parts; Access, Excel, InfoPath and Visio services; more marketing tools; dashboards, and many more advanced features

For a more detailed breakdown of the facilities available in each of Foundation, Standard and Enterprise, press here.

On-line SharePoint Environments
The "On-line" versions of SharePoint are those associated with Office 365.  Office 365 is Microsoft's "cloud computing" offering, and their answer to the increasing demand for large-scale hosted IT.  The trade-off appears to be trust in the host company's storage security versus the burden and cost of keeping pace with technological change.    Office 365 provides a range of facilities served from Internet-based Microsoft servers, such as Exchange Online, Word/Excel/etc. online, Lync and SharePoint On-line.  Seven different "plans" (price/feature combinations) are offered, as follows: P for Professional/Small businesses, E1,E2,E3,E4 for Enterprises, K1,K2 for enterprises running "kiosk" style access. 

The version of SharePoint that exists with these Office 365 plans is known as "SharePoint On-line".  It is implemented as a multi-tennanted facility in which customers effectively lease the right to build and maintain a single web site collection.  SharePoint On-Line is an online version of SharePoint Standard Server, but with some limitations.  Most notable of these is the fact that any custom applications are limited to having to work in a "sand-box".  This means no access to the local hard disk, no external requests, no access to certain prohibited features.  The limitations exist to protect other users' data, because one is operating in a multi-tennanted environment.  Programmers are using approved ways round the limitations, such as using client-side Javascript and Silverlight applications and offloading complex solutions to a 3rd party hosted environment.

Another variant of SharePoint-Online exists, targeted at companies with greater than 5000 employees, called SharePoint Online Dedicated.  With this option, the customer has greater control over their environment, which is no longer multi-tennanted.  In principle, SharePoint Online Dedicated offers greater flexibility for developers since solutions do not have to be sand-boxed, and can be "full trust".  They do, however, have to be fully tested  and then checked for compliance using Microsoft's on-line toolset, and then submitted for deployment to Microsoft.  Hence, in practice, applications need to be developed on a local server and only submitted for deployment when they are well and truly complete, tested, and ready to go live.