To validate and revise the quality model a questionnaire-based survey has been conducted.

This happened using the following process.

A: Preparation of the factors for the survey

Because of the large scope of the initial quality model, we filtered the factors to consider in two ways from 76 to 45.

Exclusion of intermediate factors serving as aggregators

We excluded intermediate factors merely serving as aggregators, that means factors which combine their subfactors to an aggregated factor. This applied to the following factors:

  • Secrets management
  • Access restriction
  • Service-orientation
  • Limited functional scope
  • Isolated state
  • Loose coupling
  • Standardization
  • Automated monitoring
  • Service independence
  • Operation outsourcing
  • Replication
  • Resource predictability
  • Configuration management
  • Distribution
  • Seamless upgrades
  • Autonomous fault handling
  • Communication indirection

Exclusion of factors less specific to cloud computing

We excluded factors which are less specific to cloud computing, that means applying also to different kinds of applications. This applied to the following factors:

  • Data encryption in transit
  • Isolated secrets
  • Least-privileged access
  • Limited endpoint scope
  • Component similarity
  • Low coupling
  • Functional decentralization
  • Sparsity
  • Cost variability
  • Isolated configuration
  • Standardized self-contained deployment unit
  • Guarded ingress
  • Invocation timeouts

B: Conducting the survey and results analysis

A more detailed report on the survey execution and results can be found in the repository qmsurvey-results

C: Updating the Quality Model based on the survey results

Finally, the results of the survey were incorporated into the model. The following changes were made:

  • Health and Readiness Checks directly impacts Automated Restarts and Automated Monitoring does not impact Automated Restarts anymore
  • Removed impact from Automated infrastructure on Modifiability
  • Removed impact from Automated infrastructure on Automated restarts and instead added impact on Recoverability
  • Removed impact from Dynamic Scheduling on Automated infrastructure
  • Removed impact from Infrastructure Abstraction on Automated infrastructure
  • Splitted Automated Infrastructure into Automated infrastructure provisioning and Automated infrastructure maintenance
  • Added impact from Built-in autoscaling on Availability
  • Removed Cost variability
  • Removed impact from Service independence on Co-existence
  • Removed impact from Configuration Management on Seamless upgrades
  • Removed impact from Secrets Management on Seamless upgrades
  • Removed impact from Separation by gateways on Reusability
  • Removed impact from Separation by gateways on Access restriction
  • Removed impact from Addressing abstraction on Communication indirection
  • Added impact from Addressing abstraction on Replaceability
  • Added impact from Addressing abstraction on Modifiability
  • Removed impact from Persistent communication on Loose coupling
  • Removed impact from Persistent communication on Recoverability
  • Added impact from Persistent communication on Fault tolerance
  • Added impact from Cloud vendor abstraction on Reusability
  • Added impact from Command Query Responsibility Segregation on Simplicity
  • Added impact from Centralized consistent logging on Accountability
  • Removed impact from Contract-based links on API-based communication
  • Added impact from Contract-based links on Adaptability
  • Removed impact from Usage of existing solutions for non-core capabilities on Standardization and instead added impact on Simplicity
  • Added impact from Vertical data replication on Analyzability
  • Added impact from Vertical data replication on Availability
  • Added impact from Use infrastructure as Code on Reusability
  • Added impact from Mostly stateless services on Testability
  • Changed Resource limits and Resource predictability to Enforcement of appropriate resource boundaries
  • Removed Communication indirection
  • Renamed Mediated communication to Consistently mediated communication and adjusted impacts based on survey and additional consideration of literature
  • Kept Communication partner abstraction, but set it to directly impact quality aspects, because “Communication indirection” was removed

The result of this revision of the quality model is the quality model as shown here:

The revised quality model including the survey results