System design based on static task graphs does not match well with modern consumer electronic devices with dynamic stream processing applications. We propose the TTL API for task graph reconfiguration services, which can be used to describe the dynamic behaviour of applications. We demonstrate the efficient implementation of the TTL API on a heterogeneous multi-processor architecture. It is possible to design dynamic streaming applications with reusable reconfiguration-aware tasks and we argue that the TTL API serves as a good starting point for standardization. Categories and Subject Descriptors D.2.11 [Software architectures]: Domain-specific architectures; C.3 [Special-purpose and application-based systems]: Real-time and embedded systems; D.2.13 [Reusable software] General Terms Design, Performance, Standardization Keywords System level design, dynamic applications, platform interface