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Glossary

This page defines and briefly explains the terminology and main concepts of the Skip framework.

  • Skip: An open-source framework that enables software developers to build and run reactive services and systems. Skip is an overarching term to refer to the full ecosystem of tools and components described here.

  • Skiplang: The Skip programming language, used by SkipLabs to implement the core logic and data structures underpinning the Skip system.

  • (Skip) Runtime: A full-fledged reactive computation engine, implemented in Skiplang and made available via bindings in other languages. The core components of the runtime are collections and mappers, which together form a graph of data and computation dependencies that the engine can use to efficiently maintain reactive computations as inputs and data are updated.

  • Service: A single-host reactive service implemented using the Skip runtime. A service provides reactive resources which can be accessed by clients or other reactive services, which specify parameters and are provided with reactively-updated data computed and maintained by the service. A service consists of some input collections, metadata to access external services (other Skip services and/or non-Skip HTTP endpoints) and a computation graph defining how to produce outputs from its inputs.

  • Resource: The output of a Skip service is one or more resources, which are updated and maintained reactively. Requests against resources can include parameters, and the corresponding results -- a resource instance specific to that client and request parameters -- are computed/updated until the client disconnects or unsubscribes. Non-reactive requests can also be made, allowing legacy clients to query reactive services' resources.

  • Collection: The core data structure over which reactive computations operate, collections associate keys with one or more values, both of which can be arbitrary JSON data. Collections can either be eager, meaning they are always kept up-to-date, or lazy, meaning that values are only computed and/or updated in response to queries for a particular key.

  • Mapper: Mappers describe computations from keys/values in one collection to keys/values in another collection. They form the edges of the Skip reactive computation graph, specifying transformations and compositions of data to produce intermediate results and outputs. Crucially, they must be deterministic and side-effect free, so that the reactive runtime can re-execute them as needed to maintain results that are both up-to-date and guaranteed from-scratch consistent. (i.e. exactly the same as the result that would be computed if the equivalent non-reactive computation were executed from scratch on the current input)

  • (Skip) Client: A thin client for a Skip reactive service which does not itself use the Skip Runtime, but operates over data which is kept up-to-date by the service.