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Kevin Hightower edited this page Aug 8, 2018 · 1 revision

USS to USS Communication and Synchronization Wrapper

This repository contains a simple, open, and API used for separate UAS Service Suppliers (USS) to communicate during UAS operations, known as the InterUSS Platform™. This flexible and distributed system is used to connect multiple USSs operating in the same general area to share safety information while protecting operator and consumer privacy. The system is focused on facilitating communication amongst actively operating USSs with no details about UAS operations stored or processed on the InterUSS Platform.

Main Features

  • Simple, open, flexible, and scalable information interface and Optimistic Concurrency Control to simplify USS to USS communication and control race conditions.
  • Effective information sharing to enable effective, deterministic conflict detection for flight planning across multiple overlapping 4D volumes from multiple USSs.
  • Effective reconstitution of flight volumes when restarting a USS or adding a USS to an existing environment.

Main Assumptions

  • Trust each USS to deconflict with known flight data.
  • Auditing is available, as all USSs can verify the authorship and addition of erroneous conflictions.
  • Deconfliction is simply defined as no overlapping flights in time and volume.

For the API specification and online test area, see https://app.swaggerhub.com/apis/InterUSS_Platform/data_node_api.

Sequence for USS information exchange

Simple Sequence When a USS wants to plan a flight, the “planning USS” performs the following steps:

  1. Discover - Communicates with the InterUSS platform to discover what other USSs have an active operation in the specific area of flight and how to contact them. Flight details are not stored in the InterUSS Platform for both minimizing data bandwidth and maximizing privacy.
  2. Sync - If there are other USSs with active operations, the planning USS contacts the other USS(s) with active operations in the area and retrieves the operational information necessary to de-conflict the operation.
  3. Plan & Verify - Once the operation is safely planned and deconflicted, the USS updates the InterUSS platform with their contact information for other USSs to use for future discovery. This update provides final verification that the planning was done with the latest operational picture.
  4. Delete - Once the operation is completed, the USS removes their information as they do not need to be contacted in the future since the USS no longer has operations in that specific area of flight. All of these operations are secured using a standard OAuth communications flow, authorized by a governmental authority or, in the absence of an authority in certain parts of the world, industry provided OAuth solutions decided by the InterUSS Technical Steering Committee.

Simple Sequence

For an additional examples, this Sequence Diagram shows a more complex operation with three USSs, two trying to plan at the same time. This Sequence Diagram shows a USS affecting multiple grids. This Sequence Diagram shows another USS updating one of multiple grids during an update. And finally, This Sequence Diagram shows different examples of protection with concurrent updates.

Files of interest in this package

  • src/storage_interface.py - Zookeeper Wrapper library in python. It contains one class of interest: USSMetadataManager with get/set/delete operations and an initialization with a Zookeeper connection string.

  • src/storage_api.py - Web Service API for the Zookeeper library. It will start a web service and serve GET/PUT/DELETE on /GridCellMetaData///, which wraps directly to the USSMetadataManager.

  • src/storage_api_test.bash - bash system test script, also shows how to start the server in bash.

  • src/storage_api_test.py - Python unit test for the Web Service API, also shows how to use the API to get, set, and delete metadata.

  • src/storage_interface_test.py - Python unit test for the Zookeeper Wrapper library, also shows how to use the library to get, set, and delete metadata.

  • coverage-html/index.html - interactive unit test coverage.

Installation

  • mkdir USS2USS
  • cd USS2USS
  • (upload USS2USS-x.y.z.tar.gz)
  • tar -zxvf USS2USS-x.y.z.tar.gz
  • sudo apt install python-virtualenv python-pip
  • cd ..
  • virtualenv USSenv
  • cd USSenv
  • . bin/activate
  • pip install kazoo flask pytest python-dateutil
  • pip install requests pyjwt cryptography djangorestframework
  • ln -sf ../USS2USS/src ./src
  • export INTERUSS_PUBLIC_KEY=(The public KEY for decoding JWTs)
  • python src/storage_api.py --help
    • For example: python src/storage_api.py -z "10.1.0.2:2181,10.1.0.3:2181,10.1.0.4:2181" -s 0.0.0.0 -p 8121 -v

Contribution

Contribution guidelines for this project

Every file containing source code must include copyright and license information. This includes any JS/CSS files that you might be serving out to browsers. (This is to help well-intentioned people avoid accidental copying that doesn't comply with the license.)

Apache header:

Copyright 2018 Google Inc.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    https://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
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