@conference {2022:sose:apiace, title = {Impact of API Rate Limit on Reliability of Microservices- Based Architectures}, booktitle = {16th International Conference on Service-Oriented System Engineering (SOSE 2022)}, year = {2022}, month = {August}, publisher = {IEEE}, organization = {IEEE}, address = {San Francisco, USA}, abstract = {Many API patterns and best practices have been developed around microservices-based architectures, such as Rate Limiting and Circuit Breaking, to increase quality properties such as reliability, availability, scalability, and performance. Even though estimates on such properties would be beneficial, especially during the early design of such architectures, the real impact of the patterns on these properties has not been rigorously studied yet. This paper focuses on API Rate Limit and its impact on reliability properties from the perspective of API clients. We present an analytical model that considers specific workload configurations and predefined rate limits and then accurately predicts the success and failure rates of the back-end services. The model also presents a method for adaptively fine-tuning rate limits. We performed two extensive data experiments to validate the model and measured Rate Limiting impacts, firstly on a private cloud to minimize latency and other biases, and secondly on the Google Cloud Platform to test our model in a realistic cloud environment. In both experiments, we observed a low percentage of prediction errors. Thus, we conclude that our model can provide distributed system engineers and architects with insights into an acceptable value for the rate limits to choose for a given workload. Very few works empirically studied the impact of Rate Limit or similar API-related patterns on reliability.}, keywords = {API Analytics}, author = {Amine El Malki and Uwe Zdun and Cesare Pautasso} } @conference {2019:map:europlop, title = {Interface Evolution Patterns {\textemdash} Balancing Compatibility and Flexibility across Microservices Lifecycles}, booktitle = {24th European Conference on Pattern Languages of Programs (EuroPLoP 2019)}, year = {2019}, month = {July}, publisher = {ACM}, organization = {ACM}, address = {Irsee, Germany}, abstract = {Remote Application Programming Interfaces (APIs) are technology enablers for distributed system trends such as cloud-native application development. API providers find it hard to design their remote APIs so that they can be evolved easily; refactoring and extending an API while preserving backward compatibility is particularly challenging. If APIs are evolved poorly, clients are critically impacted; high costs to adapt and compensate for downtimes may result. For instance, if an API provider publishes a new incompatible API version, existing clients might break and not function properly until they are upgraded to support the new version. Hence, applying adequate strategies for evolving service APIs is one of the core problems in API governance, which in turn is a prerequisite for successfully integrating service providers with their clients in the long run. Although many patterns and pattern languages are concerned with API and service design and related integration technologies,patterns guiding the evolution of APIs are missing to date. Extending our pattern language on Microservice API Patterns (MAP), we introduce a set of patterns focusing on API evolution strategies in this paper: API Description, Version Identifier, Semantic Versioning, Eternal Lifetime Guarantee, Limited Lifetime Guarantee, Two in Production, Aggressive Obsolescence, and Experimental Preview.The patterns have been mined from public Web APIs and industry projects the authors have been involved in.}, keywords = {API, API Evolution, Microservices, patterns}, doi = {10.1145/3361149.3361164}, url = {https://dl.acm.org/citation.cfm?id=3361164}, author = {Daniel L{\"u}bke and Olaf Zimmermann and Cesare Pautasso and Uwe Zdun} } @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} }