The term Hybrid in this case means a cloud application that has two kinds of components that produce the same results as if there were only one kind of component. Specifically a value-add cloud application can be built around the legacy application replacing some of it's parts that leverage the Cloud capabilities while other parts of the legacy application can remain as is and exist in the cloud and be streamed down to the user on demand.
As an example consider a real world example, a hybrid cloud offering we just delivered to the market we'll call the The Tax Planner for the Web. Tax Planner is a desktop application that is the #1 market leading product in professional tax planning software. The product was first delivered to the market as a programmed chip for the HP Calculator, yes you read that right. It was then rewritten to run on the personal computer. It is a very complex application with many of the characteristics of a legacy application that I won't go into here. The application must be updated each year for new tax legislation and retains the previous years tax calculations, in fact it supports tax calculations going back to 1987. In addition, numerous spreadsheets or worksheets are used for data entry, basically mirroring the information you would enter into a complete Form 1040, so think Schedule A, C, D etc. The customer being tax professionals and accountants are comfortable with the spreadsheet metaphor for data entry and this is challenging to replicate well in a Cloud application before HTML5. So a monolithic rewrite to move the application to the Cloud to meet market demand is a challenging project.
The solution, a Hybrid Cloud Application that leveraged the Cloud to provide features customers were looking for in a Cloud Application and leveraged the desktop to run the remainder of the legacy application to provide rich and responsive user experience. The legacy application uses a file metaphor to store clients planning data, so there wasn't the rich Client Management that customers were requesting. Customers were interested in having backup capabilities that didn't require keeping track of files. Customers were interested in collaboration and workflow capabilities across their client data. So these were features that made sense moving to the Cloud. On the other hand clients were not interested in learning a new user interface to enter plan data, think navigating the worksheets that comprise a complete Form 1040. They were happy with that part of the program.
To develop this Hybrid Cloud Application we needed a capability to stream down a virtualized version of the shipping program to the desktop on demand. The overall concept was to develop a native Cloud application that would include login/security, robust Client Management and other value add features we could easily develop for the Cloud and then when the user navigated to the client and clicked on it to open we would stream down the data entry part of the legacy application with the client data. In fact, the same shipping desktop application would be used in the Cloud application as shipped for our conventional desktop customers, we would just deal with File Open and Save through a new DLL that would make web service calls to the Cloud to display,open and save clients from the Cloud server.
To accomplish the virtualization and streaming functionality we conducted a broad market search for an appropriate technology. I won't go into all the available vendors but we chose technology from Spoon previously Xenocode developed by Code Systems Corporation, founded by by former Microsoft engineers and researchers. The technology enables application virtualization, portable application creation, and digital distribution.
We use Spoon Studio which packages software applications into portable applications, single executable files that can be run instantly on any Windows computer. It only emulates the operating system features that are necessary for applications to run to reduce resource overhead. Virtualizes portable applications run independently from other software, so there are no conflicts between them and other programs, ie no DLL conflicts.
We deploy the virtualized application in Spoon Server which we call when the user selects a client to stream the application down to the users desktop. Spoon provides browser plugins for all popular browsers that handle the client side of receiving and launching the streaming application. Once launched we create a communication link for our web services back to our Cloud application for further processing. A couple interesting features here, the initial download is fast but subsequent launching of the application can be almost instantaneous because the plugin is smart enough to determine whether the current sandboxed application is up-to-date, if it is it just launches the application rather than streaming it down again. This also insures that the application is always the latest up to date version which is critical for Tax Planners.
The Hybrid Cloud application was a big hit with our customers, they loved the cloud features and were amazed they didn't have to learn a new interface. We were also recognized by the industry earning a finalist position in the CPA Practice Advisor 2013 Innovation Awards.
You can learn more about Spoon on their website and you can try a virtualized application yourself their as well.