@book {2023:map, title = {Patterns for API Design: Simplifying Integration with Loosely Coupled Message Exchanges}, series = {Addison-Wesley Signature Series (Vernon)}, year = {2023}, pages = {544}, publisher = {Pearson Education}, organization = {Pearson Education}, abstract = {Proven Patterns for Designing Evolvable High-Quality APIs--For Any Domain, Technology, or Platform APIs enable breakthrough innovation and digital transformation in organizations and ecosystems of all kinds. To create user-friendly, reliable and well-performing APIs, architects, designers, and developers need expert design guidance. This practical guide cuts through the complexity of API conversations and their message contents, introducing comprehensive guidelines and heuristics for designing APIs sustainably and specifying them clearly, for whatever technologies or platforms you use. In Patterns for API Design: Simplifying Integration with Loosely Coupled Message Exchanges, five expert architects and developers cover the entire API lifecycle, from launching projects and establishing goals through defining requirements, elaborating designs, planning evolution, and creating useful documentation. They crystallize the collective knowledge of many practitioners into 44 API design patterns, consistently explained with context, pros and cons, conceptual solutions, and concrete examples. To make their pattern language accessible, they present a domain model, a running case study, decision narratives with pattern selection options and criteria, and walkthroughs of real-world projects applying the patterns in two different industries.}, keywords = {API Design Patterns}, isbn = {9780137670017}, url = {https://api-patterns.org}, author = {Olaf Zimmermann and Mirko Stocker and Daniel L{\"u}bke and Uwe Zdun and Cesare Pautasso} } @conference {2021:plop, title = {Patterns on Designing API Endpoint Operations}, booktitle = {28th Conference on Pattern Languages of Programs (PLoP{\textquoteright}21)}, year = {2021}, month = {October}, publisher = {ACM}, organization = {ACM}, address = {Virtual}, abstract = {Domain-driven design (DDD) is often applied when implementing microservices or communicating through APIs in distributed systems. APIs expose a published language that provides a view on entire domain models or subsets of such models. Hence, tactical DDD patterns such as Aggregate, Service, and Entity may not only structure API implementations, but also guide API specification work. In our previous work, we described endpoint-level patterns for this context. In this paper, we present three complementary patterns, namely Aggregated Domain Operation on API Endpoint, Event-Based API Endpoint Operation, and CRUD-Based API Operation. These patterns aim to derive API operations from the operations of Domain Services and Entities as well as Domain Events. We also discuss variants of these patterns, such as their combination with the patterns Command Query Responsibility Segregation (CQRS) and Publish/Subscribe. Our pattern mining work is based on a data set from an empirical study of 32 grey literature sources investigating practitioner views on deriving API designs from DDD models.}, keywords = {API, Domain-Driven Design}, author = {Apitchaka Singjai and Uwe Zdun and Olaf Zimmermann and Mirko Stocker and Cesare Pautasso} } @conference {2018:map:icsoc, title = {Guiding Architectural Decision Making on Quality Aspects of Microservice APIs}, booktitle = {16th International Conference on Service-Oriented Computing (ICSOC 2018)}, volume = {11236}, year = {2018}, month = {November}, pages = {73-89}, publisher = {Springer}, organization = {Springer}, address = {Hangzhou, Zhejiang, China}, abstract = {Microservice APIs represent the client perspective on microservice-based software architecture design and related practices. Major issues in API design concern the quality aspects of the API. However, it is not well understood today what the established practices related to those quality aspects are, how these practices are related, and what the major decision drivers are. This leads to great uncertainty in the design process. In this paper, we report on a qualitative, in-depth study of 31 widely used APIs plus 24 API specifications, standards, and technologies. In our study we identified six recurring architectural design decisions in two API design contexts with a total of 40 decision options and a total of 47 decision drivers. We modelled our findings in a formal, reusable architectural decision model. We measured the uncertainty in the resulting design space with and without use of our model, and found that a substantial uncertainty reduction can be potentially achieved by applying our model. }, keywords = {API, Microservices, quality}, doi = {10.1007/978-3-030-03596-9_5}, author = {Uwe Zdun and Mirko Stocker and Olaf Zimmermann and Cesare Pautasso and Daniel L{\"u}bke} } @conference {2018:map:europlop, title = {Interface Quality Patterns --- Crafting and Consuming Message-Based Remote APIs}, booktitle = {23rd European Conference on Pattern Languages of Programs (EuroPLoP)}, year = {2018}, month = {July}, publisher = {ACM}, organization = {ACM}, address = {Kloster Irsee, Germany}, abstract = {The design and evolution of Application Programming Interfaces (APIs) in microservices architectures is challenging. General design issues in integration and programming have been covered in great detail in many pattern languages since the beginnings of the patterns movement, and service-oriented infrastructure design patterns have also been published in the last decade. However, the interface representations (i.e., the content of message payloads) have received less attention. We presented five structural representation patterns in our previous work; in this paper we continue our coverage of the API design space and propose five interface quality patterns that deal with the observable aspects of quality-attribute-driven interface design for efficiency, security, and manageability: An API Key allows API providers to identify clients. Providers may offer rich data contracts in their responses, which not all consumers might need. A Wish List allows the client to request only the attributes in a response data set that it is interested in. If a client makes many API calls, the provider can employ a Rate Limit and bill clients according to a specified Rate Plan . A provider has to provide a high-quality service while at the same time having to use its available resources economically. The resulting compromise is expressed in a provider{\textquoteright}s Service Level Agreement. }, keywords = {interfaces, Microservices, patterns, quality}, author = {Mirko Stocker and Olaf Zimmermann and Daniel L{\"u}bke and Uwe Zdun and Cesare Pautasso} }