Rewrites and The Hybrid Life
Migrating to SharePoint Online will require SharePoint leaders to not only rewrite their custom applications, but in most cases also employ a platform as a service (PaaS) to host them. If your environment houses a number of custom features or apps, the daunting task of transitioning your existing FTC awaits.
SharePoint Online supports REST and JSON in addition to the CSOM for running custom code and making calls to SharePoint. In transitioning to SharePoint Online, all custom server code on the current installation must either be:
Once you have refactored your custom server code, you can exploit REST and achieve loose coupling. REST allows you to integrate with a non-Microsoft technology stack such as PHP and Apache. This was previously not possible due to the limitations of the SharePoint API.
You will need to set up Active Directory Federation Services (ADFS) to provide single sign-on access to Office 365 services using your corporate domain credentials. The necessity of deploying such hybrid models to fill SharePoint gaps can create complexity in both licensing and infrastructure. It’s important to have a Microsoft Partner who has done this before and educate you on the landscape.
Extensive customization and use of tightly coupled add-ons can create short and long-term pain for SharePoint to Office 365 migration. By evaluating techniques like loose coupling, Enterprise IT can improve agility and pave a smoother path forward.