Microsoft continues to target the enterprise with the introduction of a private on-ramp for Windows Azure cloud services.

The service, called ExpressRoute, allows organizations to directly connect their data centers to Azure without using the public Internet.

With ExpressRoute, Microsoft joins other enterprise-focused cloud vendors in providing a direct connection to their services. Amazon Web Services offers Direct Connect, using industry standard VLAN (virtual local area network) protocols. Rackspace offers a similar service through RackConnect.

After getting a late start, Microsoft is finally seeing momentum for Windows Azure cloud services, which was formally launched four years ago this month. Microsoft now competes head-on with AWS, Rackspace, IBM and others for what will be a US$107 billion market by 2017, according to IDC.

"We continue on an amazing growth curve," said Steven Martin, Microsoft general manager for Microsoft Windows Azure.

For instance, NBC is using Azure to stream the Sochi 2014 Winter Olympics. Every event is being streamed to qualified subscribers, a job that requires over 10,000 processor cores, according to Martin.

Windows Azure is adding about 1,000 customers a day, and Microsoft is doubling the compute capacity of Azure every six to nine months, Martin said. It now has over 250,000 customers, including 50 percent of the Fortune 100.

"I was in Silicon Valley during the height of the dot-com bubble and that pales in comparison to what I see every day right now" with the Azure expansion, Martin said.

In a 2013 survey of developers, IT analyst firm Forrester Research found that, after AWS, Azure was the platform developers would most likely use for future projects. Around 33 percent of developers opted for Azure, topping Google (28 percent), Hewlett-Packard (23 percent) and IBM (22 percent). Approximately 42 percent of developers opted for AWS.

"Azure is actually having success. There is adoption there," said John Rymer, a Forrester vice president and principal analyst for application development and delivery. "Enterprises are always reluctant to adopt a service or product that doesn't have a big following."

Microsoft offers other advantages for the enterprise as well, Rymer said. Organizations may be predisposed to work with Microsoft if they already use its products. In some cases, enterprise license agreements can be used for Azure instances.

"There is a whole procurement structure already set up. Amazon doesn't have that," Rymer said.

Microsoft also has an extensive range of partners that have built strong relationships with enterprises and can help them get to the cloud.

Martin admitted that it is a hard sale to try to persuade an organization to move existing infrastructure to the cloud. So Microsoft has been focusing on ways that Azure can extend an organization's current infrastructure as a first step.

Software test and development, Web hosting, backup and continuity of operations, and media services all fit into this model.

Each of these services can stand alone and each can be moved relatively painlessly to the cloud -- at least compared to the legacy applications with deep roots in the data center.

With Web hosting, Microsoft is offering a cost advantage. "People who are hosting Web servers are finding we can host them far more efficiently," Martin said.

With application development and testing, ease of use can be a strong incentive. "One of the pain points for developers is getting a server from IT, provisioning it, setting it up. Instead of that taking a month or six months, you can now do that in a matter of minutes," Martin said.

The cloud also offers the ability to test a newly developed application on scale. Testing how an application would run across 50 servers would be expensive in a hosting facility and even impossible using the organization's own resources.

The ExpressRoute service should help make it easier for organizations to extend their operations to Azure. Organizations can connect directly to Azure through a number of conduits.

They can link to any one of 100 Equinix data centers worldwide. They can also establish an MPLS (Multiprotocol Label Switching) VPN (virtual private network) through AT&T. Or, they can connect to a conduit provided by Level 3 Communications, thanks to a recent partnership between Microsoft and the ISP.

Using a private, dedicated connection helps ensure that data transfers happen in a consistent, predictable fashion, a guarantee difficult to make using the Internet with its ever-varying traffic levels. Throughput is guaranteed, paving the way for establishing and meeting service level agreements.

Private connections also allow the organization to easily extend its internal data-center operations to Azure. It can provision additional resources from Azure without changing its IT architecture.