@comunica/mediator-combine-pipeline

Comunica Mediator Sequential

A comunica mediator that goes over all actors in sequence and forwards I/O. This requires the action input and the actor output to be of the same type.

This module is part of the Comunica framework, and should only be used by developers that want to build their own query engine.

Click here if you just want to query with Comunica.

Install

$ yarn add @comunica/mediator-sequential

Configure

After installing, this mediator can be instantiated as follows:

{
  "@context": [
    ...
    "https://linkedsoftwaredependencies.org/bundles/npm/@comunica/mediator-combine-pipeline/^2.0.0/components/context.jsonld"  
  ],
  "actors": [
    ...
    {
      "@type": "SomeActor",
      "someMediator": {
        "@id": "#mediatorOptimizeQueryOperation",
        "@type": "MediatorCombinePipeline",
        "bus": { "@id": "ActorOptimizeQueryOperation:_default_bus" }
      }
    }
  ]
}

Config Parameters

• bus: Identifier of the bus to mediate over.
• filterErrors: Optional flag to indicate if actors that throw test errors should be filtered out of the pipeline, defaults to false.
• field: Optional field to use for ordering (if the ordering strategy is chosen). Leave undefined if the test output is a number rather than an object.
• order: Optional strategy of ordering the pipeline (increasing or decreasing).
  • For choosing to leave the order of the pipeline unchanged, leave this undefined.
  • For choosing to order by increasing values: 'increasing'.
  • For choosing to order by decreasing values: 'decreasing'.

Changelog

v2.4.0 - 2022-08-24

Added

• Add logging on timeout handlers in HTTP service
• Emit metadata in SPARQL/JSON serializer
• Enable context overriding when running SPARQL endpoint

Changed

• Move away from Node.js built-ins to avoid polyfilling in tools such as Webpack
  • Replace setImmediate by setTimeout
  • Use performance.now instead of process.hrtime
  • Avoid using htmlparser2 stream feature
  • Remove xml dependencies
  • Remove dependency on web-streams-node
• Performance improvements:
  • Update to AsyncIterator 3.7.0
  • Rewrite */+ property paths with proper backpressure handling

Fixed

• Fix propagation of iterator destroying in various places
• Fix blocking operators delaying timeout start in HTTP service
• Fix halting when error occurs in extend operation
• Avoid applying @babel/polyfill on the output code
• Close connections on uncaught exceptions in HTTP service workers
• Kill HTTP service master process if worker was forcefully killed

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