We will assume again that maintenance costs equate to 10% of the build-out cost per connection - in this case $400. This time, though, we don't have to account for tight coupling between nodes. When a node changes materially in a SOA network the change is insulated from all other nodes. At most, the service hub will have to be brought into compliance. We will conservatively assume that this will always be the case; a change to one node will always require a corresponding change on the hub. This will produce a lifetime node maintenance bill of N * 2 * ($400) = $8,000.

In addition, the hub itself represents a new source of ongoing maintenance. When it changes, the effect will likely reverberate through the network requiring corresponding changes to all nodes. Again, let's say this happens once during the life of the network and equates to (N+1) * ($400) = $4,400. Summing the two maintenance figures gives a total SOA network maintenance cost of $12,400, yielding a total lifetime cost of $52,400 - roughly half the total cost of the P2P network. A 100-node SOA network would cost $120,400 (1% of the cost of a comparable P2P network). A 200-node SOA network would cost $240,400 (0.5% the cost of a comparable P2P network). In the case of SOA, doubling the size of the network from 100 to 200 nodes also doubles its total cost, producing a linear effect.

Let's now look at return on investment. Recall that, in general, the return on one connection is a function of the number of nodes that can leverage the connection. In the P2P network, each connection links one provider to one and only one consumer. Thus, the return on a single P2P connection is always one unit of business value. On the other hand, each physical connection in the SOA network links one node to all other nodes via virtual connections through the hub. The return on a single SOA connection then is proportional to the size of the network. This means that the value of the SOA network increases exponentially as its size, or number of nodes, increases. The value of the SOA network is greater than the sum of its parts.

Examining the SOA cost and value curves together in Figure 6, we see that the graph mimics the P2P graph almost exactly: each contains one curve with a linear progression that intersects a curve with a non-linear progression. The fundamental difference, however, is that the curves' labels have been swapped. The exponential P2P cost curve has evolved into a linear SOA cost curve and the linear P2P value curve has evolved into an exponential SOA value curve.

The value of the SOA network increases exponentially over time while its costs remain linear and predictable. Upfront costs will likely be higher for SOA than P2P producing temporary deficits at the project level, but they pave the way for disproportionately high returns at the enterprise level. Once the breakeven (intersecting) point is reached, SOA delivers runaway value without negatively impacting its cost structure.

The Bottom Line
Agility is the Holy Grail anxiously sought by today's IT organizations, and the quest begins at a fork in the road. One stretch cuts through familiar P2P territory and is easily navigable by intuition; the other winds through the mysterious, uncharted regions of SOA. Many companies have been enchanted by the folklore about the SOA route but have ultimately turned away from it (or strayed from it) out of fear and uncertainty, choosing to travel the well-beaten path of P2P instead. They have chosen poorly.

The journey to agility comes at a price and IT must be ready to endure both the short-term and long-term financial burdens of its trek. Point-to-point architecture carries seductively low upfront costs, resulting in little impact at the project level. The ability to create integrated solutions with no impact on prevailing business practices makes P2P the instinctive favorite. However, microeconomic stability can quickly fester into macroeconomic chaos. As more and more one-off solutions are piled atop one another, IT maintenance costs swell exponentially and connection sprawl strangles the infrastructure. This often results in the full dedication of IT resources toward simply "keeping the lights on," leaving little left over to support new strategic business initiatives. Companies that adopt the P2P approach must be prepared to experience increasingly negative returns on their IT investments.

SOA presents exactly the opposite model. Higher upfront expenditures are required to ensure loose coupling between linked components, which inflates project budgets. This translates into initial financial losses at the microeconomic level and often catapults projects beyond conventional thresholds of risk tolerance. However, if this aversion to early-stage risk can be overcome, investments in SOA at the microeconomic level can blossom into colossal benefits at the macroeconomic level. By dramatically reducing the number of physical connections in the infrastructure and leveraging no-cost virtual connections to achieve everything-to-everything connectivity, SOA's return on investment increases exponentially as the infrastructure grows. Furthermore, since SOA keeps infrastructure costs linear and scalable, IT always has resources free to innovate and respond to changing business needs. SOA may be the road less traveled by, but for companies seeking agility it will make all the difference.