Technology has shown significant potential in developing countries, as appropriate designs matched with real world need can effectively bridge information gaps, provide greater transparency, and improve communication efficiency. Unfortunately, many developing regions environments have a lack of affordable network connectivity. Even where there is connectivity, networks are often characterized by frequent, lengthy, and unpredictable link outages, along with limited bandwidth and congested usage. These challenged network conditions, along with the desire to extend the reach of the network, motivate a different approach to developing applications that is more tolerant of intermittent network characteristics.

To address these issues, we have developed an overall system framework aimed at easing the development and deployment of applications in challenged network environments. Our approach is built on a robust implementation of the Delay Tolerant Networking architecture, a generic store-and-forward overlay network that uses medium-term storage within the network to buffer messages during link outages. We present an approach to data routing in these environments that achieves effective results by leveraging the fact that many intermittent network topologies still have an underlying topological stability. We extend the DTN architecture to include a publish/subscribe session layer, providing a more natural fit for many applications and a more robust and efficient framework for communication. Finally, we leverage this framework in TierStore, a distributed shared storage system that eases the adaptation of existing storage-oriented applications and the development of new ones.

In this dissertation, we present the design rationale for these contributions, describe and evaluate our implementation efforts, and discuss ways in which our system framework can ease the burden of application development and make deployments more robust.




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