Block osl and msl safety argument modules
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Block, OSL and MSL Safety Argument Modules. Overview. Block, OSL and MSL Modules provide the same top-level goal “{Guarantee X} is sufficiently assured” Saw how Block must guarantee certain behaviour to support the SR module

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Presentation Transcript

Overview
Overview

  • Block, OSL and MSL Modules provide the same top-level goal

    • “{Guarantee X} is sufficiently assured”

  • Saw how Block must guarantee certain behaviour to support the SR module

  • OSL, and MSL must similarly guarantee certain behaviour to support other modules

  • Note that these Modules don’t need to argue these guarantees are safe, onlythat they are provided

  • Again there are two main claims supported in these Modules:

    • Each Guarantee is assured

      • Product Argument

    • The process used in implementing the guarantees is adequate

      • Process Argument

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Block osl msl module interface
Block/OSL/MSL Module Interface

  • Module is again split into two with the process argument contained within the product argument

  • Product argument provides the following public goal to other argument modules

  • This goal would be referenced when another module requires the guaranteed service

  • The following goal requires support from other Modules

  • Note that dependencies may be identified at many different development levels

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Guarantee is assured
Guarantee is assured

  • The argument can be made by mapping the Guarantee down through each level of development

  • Once down to code level can appeal directly to test and verification evidence

  • At each level new dependencies may be identified which must be satisfied

  • Dependencies for each Guarantee are identified in DGRs

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Guarantee is assured1
Guarantee is assured

  • Each dependency at each level must be satisfied

  • This is done by the Guarantees of other modules

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Guarantee is assured2
Guarantee is assured

  • A SC contract must be formed with each of the Modules whose guaranteed behaviour is required to support a dependency

  • The Blocks may, for example, have dependencies supported by the OSL, the OSL by the MSL and so on...

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Process argument
Process Argument

  • The process argument must cover all aspects of the development process

    • Including the DGR process

  • For each aspect of the process it must be shown that it is adequate and followed

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