Global open access resource aggregation services and their requirements for data providers

The paper looks at the modern global aggregators of open access documents BASE, OpenAIRE and CORE. Their quantitative characteristics are analysed, such as the number of collected document descriptions and full texts, the number of data providers, and the availability of an application programming interface for data retrieval. The composition and types of their data providers, such as institutional repositories, open journals, publishing houses, scientific repositories of preprints, thematic digital libraries, as well as systems that are also aggregators, are considered. We also investigate what kind of information about documents these aggregators collect and how it is presented in the user interface, as well as what information is collected about data providers and how it is presented in the user interface. How the aggregator interacts with data providers, what data communication protocols are supported, and how often the collected data is updated. Also, modern aggregators based on collected data corpora, using machine learning methods, bibliometrics, webometrics, altmetrics, semantometrics, provide a range of useful services to researchers. As developers of a number of open access scientific digital libraries, we are already registered as data providers in these systems. Therefore, we are familiar with their requirements in practice. In this article, we have tried to summarise these requirements to some extent, namely: support for standard data transfer protocols, support for standard metadata sets, support for standard character encodings for content, and others.