What integration pattern should be recommended to ensure minimal rework when integrating Salesforce with multiple back-office systems?

The middleware integration pattern is recommended for integrating Salesforce with multiple back-office systems because it provides a centralized solution that enhances scalability and flexibility. Rather than establishing multiple point-to-point connections between each system, which can lead to extensive rework and complexity as new systems are added, middleware allows for a more streamlined approach.

Using middleware, you can facilitate communication and data exchange among multiple applications through a single integration layer. This centralization minimizes the need to modify each individual integration when a new system is introduced or when changes occur in one or more of the systems. Moreover, middleware often supports standardized protocols and frameworks that can be adapted for various systems, making it more manageable to keep everything in sync without significant rework.

In contrast, the point-to-point integration pattern could lead to a complex web of connections as more systems are added, making maintenance burdensome. Web mashups are typically more suited for presenting information rather than robust system integrations. Apex batch processing is a specific Salesforce feature focusing on processing large volumes of records, which does not inherently address the integration challenges posed by multiple systems. Therefore, the middleware approach is the most efficient and effective choice for minimizing rework in a multi-system integration scenario.