You have a number of disparate business systems, from purchased commodity applications, to custom developed applications that help achieve competitive advantage, to those of integrating business partners. You need all of these systems to work together, although they run on different platforms and have various service interfaces, and each set of service interfaces specifies a unique data model.
Sometimes it can work best to create a Message Bus that implements a simple Service-Oriented Architecture. Such a Message Bus must unify the service interface across all integrated applications, and they must all share a common Canonical Data Model.
This example presents a stock trading system with three subsystems: Stock Trader, Portfolio Manager, and Market Analysis Tools. I create a single Actor that implements the Message Bus, the TradingBus. Each of the subsystems is given an Actor that serves as its connector: StockTrader, PortfolioManager, and MarketAnalysisTools.
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The full text is now available as part of my book Reactive Enterprise with Actor Model on Safari Books Online.