The Internet of Things (IoT) is an emerging paradigm where practically every (physical and virtual) thing will be interconnected through innovative distributed services. Since the number of connected things is rapidly growing, IoT systems will require the composition of plenty of services into complex workflows. Thus, scalability in terms of the size of IoT systems becomes a significant concern. In this paper, we review and evaluate the fundamental semantics of existing IoT service composition mechanisms to determine how well they fulfil the scalability requirements of IoT systems. We identify scalability desiderata and, accordingly, our findings show that dataflows, orchestration and choreography do not fully satisfy such desiderata, unlike a novel composition mechanism called DX-MAN.

物联网（IoT）是新兴的范式，其中几乎所有（物理和虚拟）事物都将通过创新的分布式服务进行互连。由于互联事物的数量正在迅速增长，因此物联网系统将需要将大量服务组合到复杂的工作流程中。因此，就物联网系统的规模而言，可扩展性成为一个重大问题。在本文中，我们将审查和评估现有物联网服务组合机制的基本语义，以确定它们满足物联网系统可扩展性要求的程度。我们确定了可伸缩性需求方，因此，我们的发现表明，与称为DX-MAN的新型组合机制不同，数据流，业务流程和编排不能完全满足此类需求方。