Curriculum for

Certified Professional for
Software Architecture (CPSA)^®
Advanced Level:
Module
GREEN

Green Software - Development of resource-efficient applications

Participants are familiar with the global challenges of climate change. They know the increasing energy and resource requirements of IT and their main drivers. They can explain why IT must also address the issue of resource and energy efficiency.

Participants know the possibilities for saving energy and CO₂ through digitalisation. They know the sectors that particularly benefit from digitalisation. The difference between savings in IT and through IT is known.

Participants can quantify the energy consumption of information technology, categorise it in relation to other sectors and name the main drivers. They are familiar with trends and developments in IT and key levers.

The participants know the fields of action for saving CO₂:

Participants know the regulatory framework and the requirements it contains for saving CO₂. They know the existing certifications, such as the Blue Angel, and can use them appropriately in their work. Participants are familiar with standards such as ESG (Environmental Social Governance) and CSRD (Corporate Sustainability Reporting Directive) and their effects and consequences for companies.

Participants are familiar with the Greenhouse Gas Protocol (GHP). They are able to explain the scopes and assign emissions to the scopes. They can explain which scopes are affected when operating software in the cloud or on premise. Participants are familiar with ISO 14064-1 as a derivation of the Greenhouse Gas Protocol.

The participants know the motivation for placing green software in the company and the arguments and addressees for successfully anchoring it in the company. They can set sensible targets for the reduction of greenhouse gases for companies. Participants can explain what requirements third parties have along the value chain and how these affect their own company.

Participants know the requirements of the various stakeholders for energy-efficient software and the resulting fields of action. They know the areas with the greatest leverage for reducing greenhouse gases and can prioritize measures accordingly. Participants can classify different software systems and recognize the costs and benefits of optimization.

Participants are familiar with different quality models and can describe quality attributes relating to energy efficiency and categorise them in the quality models. In addition, participants are able to formulate quality scenarios for quality attributes in the area of energy efficiency. Depending on the intended use and the quantity structure of the application, they can consciously decide whether the quality criteria are used only for the application or for the optimisation of the development process.

Participants know the positive and negative interactions between quality attributes in the area of energy efficiency and other quality attributes. Based on this knowledge, they can recognise quality requirements that conflict with each other and develop alternative solutions to mitigate conflicts. In particular, the quality attributes of elasticity and scalability, modularity and resilience are discussed in more detail so that participants can assess their influence on energy efficiency.

Participants are able to relate resources to the service provided (business metric). They are familiar with the ISO standard Software Carbon Intensity (SCI) as a metric and understand how it can be used as a business metric.

Participants know different categories of measurement methods and their areas of application. They understand how to combine tools from the different categories for an analysis. Categories include, for example:

The participants know the methodological procedure for measuring energy consumption and CO₂ intensity. They understand that it is generally not possible to evaluate/measure absolute consumption very precisely (especially in the cloud), but how to analyse trends instead. They know proxy metrics for CO₂ intensity.

Participants know how to set up meaningful scenarios for measuring energy efficiency.

Participants understand that the procedure for measuring energy efficiency is related to the procedure for measuring performance. Participants understand how to proceed systematically in order to narrow down consumption hotspots.

Participants know how to integrate energy efficiency measurements into the development process. They know how to integrate the measurements into the CI/CD pipeline. They understand how to find a good balance for the frequency of the measurements - on the one hand (negative) trends should be recognised quickly, on the other hand the measurement itself also consumes energy.

Participants understand that the measurements must be as simple and lightweight as possible for developers to use in order to increase acceptance. They understand that energy efficiency measurements compete with quick feedback from the build. You understand that the following points are also important for acceptance:

Participants know the procedures and limits for optimising programs. They can distinguish sensible starting points from less worthwhile goals. Participants are familiar with the energy efficiency of various programming languages and can assess the areas of application for which they are suitable. They can evaluate the runtime behaviour and development speed of programming languages and make the right choice based on the requirements. They also understand the differences between ahead-of-time and just-in-time compilation, bytecode and machine code and the conflicting goals of garbage collectors.

Participants know methods for handling large amounts of data. They can assess data structures and operations on these data structures in terms of energy efficiency and make the right selection based on the given requirements. Participants know the pitfalls of using database systems and can avoid them. They are able to evaluate and optimally select different approaches for mapping relationships between entities on the basis of business requirements and quality requirements.

Participants are familiar with the principle of computational complexity and can evaluate and select algorithms in terms of their runtime and energy efficiency. They can use caches in connection with energy efficiency, know how they work (e.g. cache replacement) as well as the advantages and disadvantages. They know the possibilities and limitations of tools for detecting energy code smells.

Participants can assess different architectural styles such as distributed systems, structured monoliths or serverless and their impact on energy efficiency. In addition, they are able to assess the difference between stateless and stateful components in terms of energy requirements. Participants are familiar with the principles of cloud-native architectures and their impact on energy efficiency.

Participants are familiar with different types of communication (synchronous versus asynchronous) between building blocks in relation to the provision of data and the formats and protocols used (text-based versus binary protocols) with regard to energy efficiency. They are able to evaluate the influence of data compression on the transferred data volume and know that energy efficiency is positively influenced by a reduction in call frequency and data volume.

Participants are familiar with different types of database models (relational, NoSQL, etc.) and different database systems (Postgres, DB2, Oracle, etc.) and can make the right choice in terms of energy efficiency. They are able to select a suitable service model (self-hosting versus cloud-based managed service) for their data storage.

Participants are generally familiar with patterns such as those of the Green Software Foundation to improve the energy efficiency of an architecture. In addition, the participants are aware that a reduction in CO₂ requirements can be achieved by using more renewable energy or by reducing resource requirements. They know that by applying time and location shifting, the proportion of green energy can be increased while other patterns, such as peak shaving, reduce resource requirements.

Participants are familiar with the W3C energy efficiency proposals to be considered in web design, such as browser caching, use of a CDN, edge caching and are able to implement these in their applications. They are familiar with different file formats and types of graphic elements (e.g. animations) and are able to assess their energy efficiency.

Participants can assess the energy efficiency of a data centre. They know the Power Usage Effectiveness (PUE) and its advantages and disadvantages.

Participants know the power-load relationship of hardware. They can calculate and estimate the Server Idle Energy Coefficient (SIEC).

Participants know the main categories of cloud computing services (cloud service models), in particular "Infrastructure as a Service", "Platform as a Service", "Software as a Service" and "Serverless". They can name the main characteristics of these models and weigh up where and how they differ in terms of energy efficiency and CO₂ emission efficiency and where they are similar.

Participants know the different deployment models for cloud environments, in particular "public cloud", "private cloud", "hybrid cloud" and classic on-premise operation. They can demonstrate the opportunities and risks of these variants in terms of energy efficiency and CO₂ emission efficiency. In particular, the energy efficiency of data centres, flexibility in the selection of hardware, overprovisioning and data traffic must be taken into account.

Participants are able to assess ecologically sustainable aspects of the various providers in order to be able to take these into account when making a selection. To this end, they know how to obtain the following information, among others

In addition, the participants know the possibilities and limitations of the providers in monitoring emissions from their own resource use as provided by the providers' tools.

Participants are familiar with the challenges of energy-efficient operation and typical anti-patterns such as overprovisioning due to a lack of monitoring, a lack of automation in provisioning or unfavourable geographical distribution.

Participants know how and to what extent they can influence the CO₂ emissions of individual cloud providers by, among other things

Participants are familiar with various strategies of Infrastructure as Code, Continuous Integration and Continuous Deployments. This includes why and when these are usually used, what basic resource requirements they can have and how test execution and code analyses can affect these requirements.

Participants are familiar with methods for resource optimisation of CI/CD processes. Examples of this include the use of peak shaving and time shifting for planned builds, as well as deployment in close proximity to the target group in the context of the cloud.

Participants know methods for optimising the development and deployment infrastructure. This includes, for example, consideration of the actual resilience required, the efficiency advantages of containers over virtual machines and the use of caching for build and test artefacts.

Participants are familiar with ways to improve the resource efficiency of their test strategies and test environments. This includes, for example, the effect of different test types (load test, system test, integration test, unit test, …​) on resource consumption and the reduction of this through test gap analyses and the demand-oriented, time-limited provision of appropriate test environments.