Cloud, cloud, cloud. The buzzword of a few years ago is becoming reality for many organisations today but there are still some industries and use cases that have significant obstacles to overcome. Recent research from one hosting company suggests that this is changing though – with public cloud usage set to double from 7% to 14% and hybrid cloud growth to almost triple from 10% to 28% over the next three years.

Hybrid cloud is a term used to describe an architecture with elements of the solution provided from the public cloud (e.g. Microsoft Azure or Office 365) in conjunction with elements delivered on-premises (i.e. in a customer or managed service provider’s datacentre).

Whilst some cloud providers consider hybrid as little more than a tactical bridge to help with transition to their infrastructure as a service (IaaS) and platform as a service (PaaS) solutions, those using software as a service (SaaS) are really embracing a hybrid cloud as part of their architecture.

For users of Microsoft’s Office 365 productivity services, hybrid cloud offers some real opportunities, partly because the online services have grown from an established on-premises suite of software applications so the user experience with Exchange, Skype for Business or SharePoint is similar regardless of where the service is running.

In this blog post, I’m going to examine some of the scenarios where a hybrid cloud solution might be used with the common Office 365 workloads.

Exchange Hybrid

Whilst Office 365 is highly configurable, it’s not customisable. The Office 365 service descriptions are fixed – that is to say that the service described is standard to all customers (unless they have a dedicated tenant) – and, whilst an administrator can change the configuration, certain levels of control require an on-premises infrastructure.

For example, hosting mailboxes in the UK, installing tightly-coupled applications that need access to Exchange Servers, or anything that goes outside the boundary of the standard Exchange Online service would need on-premises Exchange servers to meet the requirements. However, if the restrictions that prevented all users from moving to the cloud only affected a portion of the organisation, there could still be advantages in moving other groups of users.

A hybrid deployment provides a seamless look and feel of a single Exchange organization when there’s actually two: an on-premises Exchange Server 2013 organization and Exchange Online in Office 365. Hybrid Exchange enables:

• Secure mail routing between on-premises Exchange and Exchange Online with a shared namespace, together with centralised control of the inbound and outbound mail flow
• A unified global address list (GAL), free/busy and calendar sharing, a single Outlook WebApp URL, message tracking, MailTips and multi-mailbox search for both organizations.
• The ability to move mailboxes back and forth between the on-premises and cloud organizations.
• Centralised mailbox management using the on-premises Exchange Admin Center (EAC).
• Cloud-based messaging archiving for on-premises Exchange mailboxes.

Exchange Server 2013 now includes a Hybrid Configuration Wizard (HCW) which does the heavy lifting to set up a hybrid Exchange environment (previously it required manual configuration). There are some limitations to consider around inherited and delegated permissions and multi-forest Exchange organizations with legacy versions of Exchange. More details are available on TechNet.

Lync Skype for Business Hybrid

Skype for Business Online doesn’t currently include any enterprise voice capabilities. Users can host meetings, send/receive instant messages, publish presence, conduct direct peer-to-peer conversations through the Lync or Skype for Business clients and even dial-in to conferences (when integrated with a qualified audio conferencing provider) but there is no integration with PBX telephony systems.

One way around this is to run on-premises Lync or Skype for Business servers for enterprise voice, sharing a SIP namespace with the cloud tenant. This is also known as a “split domain” scenario.

Skype for Business Hybrid should not be confused with the Lync Online “hybrid voice” option that was withdrawn in 2013. Whereas hybrid voice allowed cloud users to break-out to on-premises solutions for voice, in a split domain scenario:

• Voice-enabled users are hosted on-premises for all of their Lync/Skype for Business services.
• Users who don’t need enterprise voice capabilities can be hosted in Skype for Business Online.
• Both sets of users can collaborate as though they were in the same Skype for Business organisation.

More details are available on TechNet and it’s also worth noting that, in order to facilitate Skype for Business hybrid scenarios, Office 365 E4 subscriptions include licenses for running on-premises Lync/Skype for Business infrastructure.

SharePoint Hybrid

A SharePoint Hybrid solution allows some data to exist in the cloud with some data retained on premises, perhaps for compliance reasons, during a staged migration, or for connectivity with business applications. There are various topologies available around search and business connectivity services (BCS).

• One-way outbound search allows SharePoint Server 2013 on-premises to query the SharePoint Online search index and return federated results.
• One-way inbound search is the equivalent but with on-premises results returned to the SharePoint Online search.
• Two-way search allows both environments to query each other’s indices and return federated results.
• One-way inbound or two-way BCS solutions allow SharePoint Online to connect to on-premises SharePoint Server 2013 and onwards to OData service endpoints.

More details are available on TechNet.

In conclusion

Adopting Office 365 doesn’t have to be a cloud-only solution – customers can choose to run some workloads on-premises alongside other workloads in the public cloud (e.g. SharePoint on-premises with Exchange Online), or the hybrid scenarios described above may offer additional flexibility.

For some workloads, e.g. Yammer, there is no on-premises equivalent and it seems certain that in some point in the future we’ll only be considering public cloud solutions. That day is still some way off though and with Microsoft releasing Skype for Business Server 2015 and prepping Exchange Server 2016 and SharePoint Server 2016, the use of on-premises infrastructure in a hybrid configuration looks to offer the best of both worlds for the time being.

This post originally appeared on the Microsoft TechNet UK blog.