48 connection approach, as well as other solution version described in this chapter, it is necessary to apply the principle of “open by default”, whose “source” system makes the accumulated data available by the principle of open data. Application of the closed two-way connection should be particularly justified by the restrictions or special technical restrictions regarding data utilisation defined in legislation that prevents any possibility of the re-use of these data. In order to further improve the security and speed of the data exchange, especially in those IS, which provide data through the State Information Systems Integrator, it is necessary to improve technological solutions of the corresponding IS cross-system integration interfaces, making them as a relevant IS functionality. Those basic data accumulated in IS, the usage of which in the single public administration data space is particularly intense, would be technologically replicable into State Information Systems Integrator in the technologically optimised highperformance high-speed data storage. As an example of such data is the information related to the identification of inhabitants and businesses. So far the development and hosting of SIS interfaces in the State Information Systems Integrator have not been sufficiently active, therefore, SIS should be targeted to the connection to State Information Systems Integrator to ensure that all data, required for more than one user in the public administration or outside of it, are available via the State Information Systems Integrator. Given the expected increase of the utilisation of State Information Systems Integrator, it is necessary to improve also functionality and operation of State Information Systems Integrator, as well as from, technical, organisational and legal aspects. Additionally, a principle should be introduced that the collaboration between National Information System and local governments’ IS, as well as private sector IS, is organised through a centralised State Information Systems Integrator. Regarding the SIS cooperation with EU institutions and other EU Member States institutions’ IS, it is necessary to use a centralised State Information Systems Integrator as far as possible if it does not conflict with EU laws and the EU’s centralised IS architecture. It should be noted that the same approach applies to geospatial information, the exchange of which between SIS, a geospatial data uniter should be used. In order to achieve a common understanding and actions of the involved parties to practically create and implement a single data space, it is necessary to develop public administration ICT architecture document which will cover the interoperability architecture of information systems and data exchange principles in this architecture. 5.3.4 Optimisation of ICT Infrastructure National ICT infrastructure optimisation was initiated in 2010 with an informative report “On the Usage of Microsoft Infrastructure Software and Possibilities of Information and Technology Infrastructure Optimisation in Ministries and Their Subordinate Institutions”38. The report states 38 Informative report “On the Usage of Microsoft Infrastructure Software and Possibilities of Information and Technology Infrastructure Optimisation in Ministries and Their Subordinate Institutions” http://polsis.mk.gov.lv/view.do?id=3354 information_society_development_guidelines_2014_2020.docx; Information Society Development Guidelines 2014-2020