Microsoft has published and made available a free guide for developers for your SharePoint Online development.
This guide walks you through some of the rich features that are available to developers and designers in SharePoint Online in Office 365. It provides an overview of the feature set and extensibility points for SharePoint Online, and a discussion of how to create solutions for this new environment.
This guide begins by describing the types of solutions you can build, and then addresses the developer tools for SharePoint 2010, the new platform features, and the solution deployment architecture.
Use the SharePoint Online for Office 365 Developer Guide to gain knowledge and understanding of SharePoint Online within Microsoft Office 365, and the rich features available to developers and designers.
SharePoint Online opens a new arena for developers to create solutions for customers who use the Microsoft Office 365 service instead of maintaining on-premises servers, or for clients who are looking to take advantage of hybrid deployments where some data is stored behind the firewall and other data is off-loaded in the cloud.
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