The charge-back model adds complexity, Unisys' Ott notes. "Pay-as-you-go makes it harder," he comments. When it comes to cost allocation, Ott recommends more of a federated approach, in which everyone puts in money and investment up front, even though some lines of business may not experience the benefits of their investments for years.
And inevitably, with new governance policies comes the need for new organizational models. An SOA implementation will bring about many changes in the financial institution, including new partnerships between business and IT, according to TowerGroup, which asserts that such partnerships are integral to overcoming the challenge of breaking down the walls between businesses in the bank.
Measuring the success of SOA after deployment can be less of a challenge -- especially if a bank has established clear goals ahead of time. Wachovia's CIB unit measures its SOA results with two indicators: time to market and the number of reusable parts, relates the bank's Bishop. So far, he says, it has experienced about a 40 percent cost avoidance over three years using SOA rather than a traditional technology architecture.
Bishop offers advice for banks just starting on their SOA journey. "You've got to focus," he says. "You've got to be committed. You need to do it in incremental building blocks. SOA needs to be business-aligned and needs to have a top-down map and a bottom-up approach." And bank executives need to know what they're getting into: "It's a full-time part-time job for even the highest-ranking executives," Bishop says. **