ASCE 5.1 delivers enhanced functionality, support for GSN v3 and next generation assurance case design
Adelard, part of NCC Group, is pleased to announce the release of ASCE 5.1. The release signifies an important milestone in the evolution of ASCE with the new version incorporating improvements to many familiar features as well as the introduction of new features aimed at embracing the next generation of assurance case design, Assurance 2.0.
As with previous releases, customers should be confident in a smooth upgrade path to ASCE 5.1. Upgrade is free of charge for customers with a current support and maintenance contract and all users are encouraged to upgrade to take advantage of the feature improvements. Once upgraded, customers have the option to further upgrade their existing assurance cases to one of two new schemas, GSN 3.0 and ASCAD 2.0, more details below.
ASCE 5.1 includes improvements in functionality with changes to the network encoding management system and internationalisation support, GUI improvements, enhancements to the find and replace feature, improved management of headings in the node editor, and updates to status field editor, resource manager, GSN auxiliary functions, embedded issues, and one-click export plugins. Windows 7 support is discontinued and support for the new Windows 11 operating environment, MS Office 365 and MS Office 2021 is introduced as is a switch to a 64 bit only architecture to improve performance.
Adelard has long been at the forefront of tracking and leading development in assurance case methodology. As a direct result of this continued research, ASCE 5.1 has full support for GSN v3, the latest GSN community standard, and a new schema, ASCAD 2.0, the gateway to the design of next generation assurance cases in CAE (Claims, Arguments, Evidence). ASCAD 2.0 is Adelard’s practical implementation of Assurance 2.0, a new framework aimed at increasing the rigour in the reasoning and assessment of evidence employed.
Assurance 2.0 is the response to the new challenges facing traditional system assurance such as those of autonomous systems with functions driven by machine learning and artificial intelligence coupled to system security, ultra-fast development targets and the persistent issues of efficient, effective, and timely assurance.
Deploying or upgrading to ASCAD 2.0 brings new features to assurance case design, features such as defeater and comments management, and CAE Blocks structure validation for argument steps. Support for ASCAD 1.3 will remain, however upgrading to ASCAD 2.0 will encompass all the ASCAD 1.3 design features as well as priming the new features. A new schema update environment will make upgrading schemas much easier and once upgraded, users will have the new features at their fingertips in readiness to explore the merits of next generation assurance cases.
Further information on the changes and new features of ASCE 5.1 can be found below.
Summary of improvements
- Enhanced methodology support: ASCAD 2.0, GSN v3 and Modular GSN v3.
- New plugins for managing comments and defeaters in ASCAD 2.0 assurance cases.
- Performance improvements (e.g., when working with large networks).
- GUI improvements (e.g., improved readability, naming).
- Improvements to the existing functionality (e.g., support for hotkeys in Find and Replace dialog, improved management of headings in the node editor, option to display extra warnings when deleting nodes)
- Updates to the existing plugins (e.g., Status field editor, Resource manager, Embedded issues).
- Support for the latest OS and MS Office releases: Windows 11, MS Office 365, and 2021. Support for Windows 7 discontinued.
- Full transition to 64-bit architecture.
- Better forward compatibility with ASCE 4 with improved encoding management feature.
- Improved error reporting throughout the product (e.g., when comparing ASCE networks, Fault tree plugin, One-click export plugin).
- Improved ASCE Help documentation and plugin manuals.
- Improved support for different regional settings, locales and date formats.
ASCAD 2.0 and CAE blocks
Assurance 2.0 is a modernised framework that supports innovation and continuous incremental assurance. It makes assurance more rigorous, with increased focus on the reasoning and evidence employed, and explicit identification of defeaters and counterevidence. Assurance 2.0 advocates the use of CAE Blocks, which provide mechanisms for separating inductive and deductive lines of reasoning, and for managing the side conditions necessary to justify argument steps.
ASCAD 2.0 is a new schema released with ASCE 5.1 to support the Assurance 2.0 framework. It incorporates the new node types and links necessary for the use of CAE Blocks, as well as managing defeaters and comments in assurance cases. Users are encouraged to use this new schema, and an option to easily upgrade from the previous versions of the schema is available. However, support for ASCAD 1.3 and ASCAD 1.2 will remain for the short term.
More information on Assurance 2.0 can be found in Robin Bloomfield's and John Rushby's paper "Assurance 2.0: A Manifesto".
An introduction to CAE Blocks can be found in Robin Bloomfield's and Kateryna Netkachova's paper "Building Blocks for Assurance Cases".
Over the years, various approaches have been proposed to increase rigour and confidence in assurance and safety cases. One such approach, currently the subject of much ongoing research, is defeater management.
Adelard has been researching the concept of defeater management to increase confidence in assurance cases. ASCE 5.1 now has support for defeaters in both GSN 3 and ASCAD 2.0 networks.
Defeater management in GSN 3 is implemented as defined by the latest version 3 of the GSN Community Standard.
Defeater management in ASCAD 2.0 allows authors and reviewers of assurance cases to add defeater nodes to the ASCE canvas and use ASCE’s editing tools to provide the challenge narrative. The defeaters can then be addressed by adjusting the assurance case or analysing and disputing the challenge, with the aim of addressing all defeaters. The response to defeaters can be documented in the defeater node narration and preserved as part of the assurance case to assist further revisions and reviews.
Defeaters are most helpful when they are used to capture the journey of development as they help to document the issues flagged up and discussions held while creating the case. This recording of defeaters and the narrative that follows serves to increase the rigour and confidence in the case.
Implementation of defeater management in ASCAD 2.0 includes: hide/show all defeaters and hide/show addressed defeaters, with the options available globally for the entire network as well as locally for a specific subtree. Table view with filter and export capabilities is also extended to include defeater nodes.
Additionally, a new “defeater” item type is now available in the Embedded issues plugin to add defeaters directly into the node narrative content. This feature is not schema-specific and can be used in assurance cases created with any notation.
Further insight on defeater methodology can be found in Robin Bloomfield's and John Rushby's paper "Assurance 2.0: A Manifesto".
A new comments management feature is available in ASCE 5.1 for ASCAD 2.0 assurance cases. Users now can add a comment node and use the new link type ‘comments on’ to link comments to other nodes on the ASCE canvas. The comment node is designed to communicate additional comments or notes within an assurance case. The response to each comment is typically documented in the node narration and is preserved as part of the case to assist further revisions and reviews. A fully addressed comment node can be marked as ‘addressed and can be hidden from the canvas if so desired. All comments, whether hidden or not, are preserved within the assurance case.
ASCE’s node editing features can be used to create the narrative within a comment node. New features permit users to hide and show all comments or the addressed comments and sub-comments throughout the network, with additional options to hide or show comments within a subtree.
GSN Version 3
ASCE 5.1 introduces support for the new version 3 of the GSN community standard. Users upgrading their schema from GSN 1.3 to the latest version GSN 3.0 will notice some changes. Full details of these changes are available in the help files and on the ASCE support website. For example, in line with the new version 3 of the standard, Model element is deprecated and replaced with Context element and there are both new and changed link types and node properties. An option to upgrade a network from an older version of the schema to the newer version is now available in the ASCE 5.1 Project Properties window.
The GSN v3 standard defines extensions to GSN: Argument Pattern, Confidence Argument and Dialectic extensions. All three are fully supported in ASCE 5.1 using the GSN 3.0 schema. Argument Pattern extension has been updated, Confidence Argument and Dialectic extensions are both new for the GSN v3 standard. Confidence Argument extension allows a separate argument to be made about the confidence in the element or relationship. Dialectic extension permits challenges to the argument to be recorded and managed.
Modular Extension is supported in ASCE 5.1 via a separate Modular GSN plugin available on a commercial basis. A new modular GSN package has been created to support Modular Extension in line with the latest GSN v3 standard.