In dataspaces, federation services facilitate key functions such as enabling participating organizations to establish mutual trust and assisting them in discovering data and services available for consumption. Discovery is enabled by a catalogue, where participants publish metadata describing themselves and their data and service offerings as Verifiable Presentations (VPs), such that other participants may query them. This paper presents the Eclipse Cross Federation Services Components (XFSC) Catalogue, which originated as a catalogue reference implementation for the Gaia-X federated cloud service architecture but is also generally applicable to metadata required to be trustable. This implementation provides basic lifecycle management for DCAT-style metadata records and schemas. It validates submitted VPs for their cryptographic integrity and trustability, and for their conformance to an extensible collection of semantic schemas. The claims in the latest versions of valid VP submissions are extracted into a searchable graph database. The implementation scales to large numbers of records and is secure by design. Filling the catalogue with content in a maintainable way requires bindings towards where data and service offerings are coming from: connectors that expose resources hosted in an organization's IT infrastructure towards the dataspace. We demonstrate the integration of our catalogue with the widely used Eclipse Dataspace Components Connector, enabling real-world use cases of the German Culture Dataspace. In addition, we discuss potential extensions and upcoming integrations of the catalogue.

翻译：在数据空间中，联邦服务通过促进参与组织间建立互信关系，并协助其发现可供消费的数据与服务，从而实现关键功能。发现功能通过目录实现，参与者可在其中以可验证声明（VP）的形式发布描述自身及其数据与服务产品的元数据，以供其他参与者查询。本文介绍了Eclipse跨联邦服务组件（XFSC）目录，该目录最初作为Gaia-X联邦云服务架构的目录参考实现，但也普遍适用于需要可信的元数据场景。该实现为DCAT风格的元数据记录与模式提供基础生命周期管理，对提交的可验证声明进行密码学完整性、可信度验证，并确保其符合可扩展的语义模式集合。有效VP提交的最新版本中的声明将被提取至可搜索的图数据库中。该实现可扩展至海量记录规模，且具备原生安全设计。为以可维护的方式填充目录内容，需要建立与数据及服务来源的绑定机制：即通过连接器将组织IT基础设施托管的资源暴露至数据空间。我们展示了该目录与广泛使用的Eclipse数据空间组件连接器的集成方案，实现了德国文化数据空间的实际用例。此外，本文还探讨了该目录的潜在扩展方向及即将开展的集成计划。