Where SOA Meets Cloud

David Linthicum

The Cloud, Agility, and Reuse Part 1

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Agility and reuse are part of the value of cloud computing, and each has its own benefit to enterprise architecture.  In the past, as an industry, we've had issues around altering the core IT infrastructure to adapt to the changing needs of business.  While cloud computing is no "cure all" for agility, it does provide a foundation to leverage IT resources that are more easily provisioned and thus adaptable. 

 

Agility has a few dimensions here:

 

First is the ability to save development dollars through reuse of services and applications.  It's helpful to note that many services make up an application instance.  These services may have been built inside or outside of the company, and the more services that are reusable from system to system, the more ROI from our cloud computing. 

 

Second is the ability to change the IT infrastructure faster to adapt to the changing needs of the business, such as market downturns, or the introduction of a key product to capture a changing market.  This, of course, provides a strategic advantage and allows for the business to have a better chance of long-term survival.  Many enterprises are plagued these days with having IT infrastructures that are so poorly planned and fragile that they hurt the business  by not providing the required degree of agility. 

 

Under the concept of reuse, we have a few things we need to determine to better define the value.  These include:

 

·      The number of services that are reusable.

·      Complexity of the services.

·      The degree of reuse from system to system.

 

The number of reusable services is the actual number of new services created, or, existing services abstracted, that are potentially reusable from system to system.  The complexity of the services is the number of functions or object points that make up the service.  We use traditional functions or object points as a common means of expressing complexity in terms of the types of behaviors the service offers.  Finally, the degree of reuse from system to system is the number of times you actually reuse the services.  We look at this number as a percentage.

 

Just because we abstract existing systems as services, or create services from scratch, that does not mean that they have value until they are reused by another system.  In order to determine their value we must first determine the Number of Services that are available for Reuse (NSR), the Degree of Reuse (DR) from system to system, as well as the Complexity (C) of each service, as described above.  The formula to determine value looks much like this:

 

Value = (NSR*DR) * C

 

Thus, if you have 100 services available for reuse (NSR=100), and the degree of reuse at 50 percent (DR=.50), and complexity of each service is, on average, at 300 function points, the value would look like this:

 

Value = (100*.5) * 300

 

Or

 

Value = 15,000, in terms of reuse.

 

If you apply the same formula across domains/data centers, with consistent measurements of NSR, DR, and C, the relative value should be the resulting metrics.  In other words, the amount of reuse directly translates into dollars saved.  Also keep in mind that we have to subtract the cost of implementing the services, or, creating the cloud computing solution, since that's the investment we made to obtain the value.

 

Moreover, the amount of money saved depends upon your development costs, which vary greatly from company to company, data center to data center.  Typically you should know what you're paying for functions or object points, and thus it's just a matter of multiplication to determine the amount of money you can save by implementing a particular cloud computing solution.

 

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This blog is your first step toward understanding the issues you will face as cloud computing and SOA converge. The movement to cloud computing is a disruptive change that IT departments will soon face as SOA and cloud computing begin to have an effect on the modern enterprise. IT managers must learn how to give as well as take information in this new, shareable environment, while still protecting their company's interests. Innovative companies will take advantage of these new resources and reinvent themselves as unstoppable forces in their markets. Those who don't take advantage of this revolution will become quickly outdated, perhaps out of business.

David Linthicum

David Linthicum is the CTO of Blue Mountain Labs, and an internationally known distributed computing and application integration expert. View more

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