ITU‐T's Technical Reports and Specifications 697 Provide topic, department, location, label or map to search. Data services Provide a variety of machine‐readable data format, including XML, RSS, CSV/Text, KML/KMZ (Geospatial Data Format), ESRI Shapefile (Geospatial Data Format); Provide the statistics of data download and data query; Provide the name, source institution, links, format, size, release data, etc.; Provide data related maps and visual display. APP service Provide some types of applications, including website and mobile app; APP List: include name, description, operating platform, download links, developer information and so on; APP Submission: include name, label, classification, description, version, charge mode, updated time, size, operating platform, download links and so on; APP Download: include name, label, classification, version, charge mode, rating, guidelines, and so on. Developer center Provide \"My Applications\" account; Provide related learning, exchanging, authorization, development and management of application; Provide different types of API for registered users to download data or to call data: API download, API introduction, guide book, sample code, and other common problems. Service center Provide advices and Q&A through communication and interaction,include recommendations for improvement, score and rank data resources and so on; Intercommunion and Interaction among users, including data resource evaluation; Intercommunion and Interaction between users and portal: include e‐voting, online questionnaires, online communication; Provide personalized participation mechanisms through social network site (SNS) technology; Provide customized data based on a hot topic and user interest. Map service Provide data query services through binding data resources and geographic information, and then directly present on the map. (2) Open data technology The open data portal is supported by four main technologies, the metadata management, the linked data technique, the data visualization and social networks. Metadata Management Provide minimum data set; Provide metadata structures.