A Unified Application Programming Interface for Bundle Protocol Applications

Next space missions should rely on the DTN architecture and its associated Bundle Protocol (BP) to cope with the challenges faced by interplanetary links, such as long delays and disruption. This has led to new BP implementations or new releases, incorporating version 7, recently standardized by IETF. Although positive per se, this has exacerbated an already existing fragmentation problem, as every implementation has its own API and its own set of bundle options supported, which is a significant obstacle to the development of third party applications. To alleviate this problem, a new “abstracted” API for bundle protocol applications, called Unified API, has been developed during this thesis, and it is presented here. The Unified API is a complete refactoring of the old “Abstraction Layer”. As the predecessor it aims to decouple a DTN application from the BP implementations, with great advantages in terms of portability, maintenance and interoperability. However, the Unified API is more ambitious and it has the goal to present also a new API, now much closer to the familiar UDP socket and, more generally, to facilitate the development of new DTN applications as much as possible. To obtain this, the whole structure has been organized in three layers, of which only the top one is seen by applications. This layer consists of four blocks, of which the most important is the “Socket” block. The other blocks provide the programmer with high-level tools to create and modify a bundle, to parse the input string, to implement conditional prints etc. The Unified API is compatible with most BP implementations (DTN2/DTNME, ION, IBR-DTN, µD3TN). As them, it is released as free software and it is going to replace its predecessors in the next release of the DTNsuite, the Unibo collection of DTN applications included in ION, the DTN implementation by NASA JPL. The hope is that the Unified API will encourage third-party programmers, thus contributing to the success of DTN networking.