13. Publication de own geodata layers via the access control system of the geoportal

Each provider of products and geodata can publish own geodata webservices and use the access control layer provided by the geoportal webservice proxy.

For a better understanding, the difference between viewing geodata layers in the geoportal's online mapping tools and retrieving geodata contents via online access to webservices should be explained:

Whereas the mapping tools are designed to run within an internet browser - with the duly reduced functionality palet - the geoportal also offers an interface for professional GIS applications to directly connect to the geodata via standardized webservices.

This connection is only possible if

  • the customer has the necessary credentials, and
  • if the customer uses a GIS application that is able to connect to standardized OGC WMS (Web Map Server) or WFS (Web Feature Server) services.

The geoportal offers a great choice of webservices, part of which are protected by ghe geoportal's internal access control system. Of course every provider is free to publish his geodata independently from the geoportal, but he can also choose to integrate his webservices with the access control layer of the geoportal, instead of investing himself in such a system. In this case, his webservices are published with an URL of the geoportal, and they are accessed via the geoportal's “OGC proxy”.

This connection to a proxy can actually be done for WMS services as well as for WFS services.

The geodata webservices can be made available either to the general public, or to a precisely defined target user. This happens through detailed OGC access profiles in the geoportal's management system. The restrictions to be implemented in the profiles are decided by the provider and ACT in common.

This publication of geodata content via the OGC proxy can of course not be done by the provider himself. It needs co-operation between the data provider and ACT.

The steps to publish new geodata layers via the geoportal are the following:

13.1 Agreement about the geodata layers to be published

When a new user joins the geoportal as geodata and product provider, he decides together with the responsible persons at ACT which geodata layers he wants to publish on form of an integrated WMS or WFS webservice, as well as the possible restrictions he wants to be applied upon his webservices. There may be supplementary issues to discuss, like for example the possibility to allow reprojections in other SRS by the proxy, or the data rendering in different file formats.

These decisions can be documented in the written agreement which is signed between the representatives of ACT and the provider organisation, when the user account is opened.

The access restrictions that can be offered by the geoportal for the “proxied” webservices, are the following:

  • Layer visibility limited to certain users (per root account), or only accessible to the provider's organisation.
  • Layer visibility limited to a certain scale range
  • Layer visibility limited to a certain geographic extent (BBox, or polygon)

The provider can always ask ACT to change the settings of the access restrictions. In this case, the written agreement has to be adapted.

13.2 Mise en place de webservices de géodonnées normalisés

Le géoportail est entièrement construit sur la base d'échanges de données selon des spécifications et normes en vigueur, notamment sur l'utilisation de webservices normalisés basant sur la spécification WMS (Web Mapping Server) de l'OGC (Open Geospatial Consortium).

Pour publier un tel webservice à l'aide du proxy WMS du géoportail, le fournisseur doit d'abord mettre en place un tel webservice conforme à la spécification WMS. Il a le libre choix des softwares propriétaires ou open source qu'il entend utiliser pour ce faire. L'essentiel est la capacité du service de répondre aux appels normalisés selon la norme WMS.

Il doit ensuite fournir à l'ACT les informations nécessaires pour accéder ce webservice, comme l'URL et les données nécessaires pour la sécurisation (mot de passe). L'ACT procédera à des tests d'intégration du webservice, en respectant les spécifications retenues dans la convention sus-mentionnée.

L'ACT pourra essayer d'assister le fournisseur dans la résolution de problèmes relatifs aux webservices OGC.

13.3 Intégration du webservice dans le proxy WMS/WFS du géoportail

Après avoir effectué des tests concluants, l'ACT ajoute les nouveaux webservices en provenance du fournisseur dans le proxy WMS du géoportail.

Les nouvelles couches pourront être accédées de la même manière que les autres webservices disponibles, moyennant protection par mot de passe.

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