Social Linked Data (Solid) origins from the idea of a decentralized social Web with separated data, identities, and applications. This demo provides a proof of concept to show the usability of the Solid specifications in an enterprise data exchange scenario. The loan request of a company via a tax accountant serves as the use case. Most companies face the challenge to exchange data between enterprises. Currently, common solutions are proprietary cloud services provided by corporations like Microsoft, Google, Dropbox, Nextcloud, and ownCloud. However, these don't ofer the decentralization and trustworthiness needed for some use cases with more confidential enterprise data. Solid (derived from “Social Linked Data”) is a collection of technological specifications for read/write Linked Data supported by authentication and authorization [1]. It builds upon the RESTful HTTP service specification of the Linked Data Platform (LDP) 1. Solid uses established (Semantic) Web standards [2] and is therefore easy to integrate and use. It is also independent of any centralized element. Furthermore, Solid has lightweight specifications that make no restrictions regarding the backend database used. The physical Solid Pod2 location and identity provider can be freely chosen or self-hosted. Additionally, Solid provides detailed and flexible access control, which is crucial for enterprise use cases.
Therefore, this demo shows the usage of Solid for the data exchange process between multiple enterprises. For confidential enterprise data, the Solid specifications build a foundation we use for this proof of concept and will enhance in future work to ensure a level of trust for the data exchange process. For an actual use case (see Section 2), we partnered with DATEV eG, a German software company particularly providing business software (e.g., for tax accounting) on large scale.
While the development of Solid was motivated by a decentralized social Web for personal
data [
The International Data Spaces (IDS)4 and GAIA-X5 initiatives aim for a complete ecosystem
regarding data sovereignty and trustful data sharing. IDS is further developed at this point in
time, but still just starting with implementations. IDS and GAIA-X partially utilize Semantic
Web standards like LDP and ontologies [
We investigate the data-sharing scenario of a loan request for tax accountants. Figure 1 shows the process, which is abstracted but based on real life. A company named Nordwind asks a bank named Grünbank for a loan. Grünbank needs to check Nordwind’s finances to grant a loan. Therefore, Nordwind instructs its tax accountant, Dr. Ehrlich, to provide an attested summary of its finances to Grünbank. With that information, Grünbank can decide on the loan to Nordwind. This scenario serves as our use case for data sharing in an enterprise environment following the Solid approach.
An Angular app that provides a user interface to the employees of the involved organizations to execute the use case. The app reads/writes RDF data on the Solid Pods using HTTP requests.
An instance of the Solid App. It runs in the web browser of a Nordwind employee. The app ofers features adapted to Nordwind users.
An instance of the Solid App. It runs in the web browser of an Ehrlich employee. The app ofers features adapted to Ehrlich users.
An instance of the Solid App. It runs in the web browser of a Grünbank employee. The app ofers features adapted to Grünbank users.
A Solid Pod that contains Nordwind’s financial data.
A Solid Pod that contains Nordwind’s financial documents.
The identity providers host Solid servers that contain the profile documents belonging to a WebIDs. We use multiple existing identity providers to create WebIDs for employees of the three organizations.
To implement the use case with Solid, we set up a Solid App, multiple Solid Pods for data, and
several identities represented as WebIDs6 used for access control [
The sequence diagram in Figure 2 shows the usage of the setup for the use case. The actors in the diagram are three instances of the Solid App with corresponding features of a logged-in user, the Nordwind Pod, and the Ehrlich Pod. We omit here authentication and authorization steps for simplicity, both are provided by the Solid server. The presented sequence starts at the Nordwind App, from where accounting transaction data is posted to the Nordwind Pod. After this data is pulled with a GET request to the Ehrlich App, an audited Cash Basis Accounting8 document (CBA) is created as a summary of the financial situation of Nordwind. The CBA is then posted to the Ehrlich Pod. Afterwards, its Access Control List9 (ACL) is successively
retrieved, adjusted, and overwritten to change the authorization to allow access to the CBA for Grünbank employees. Afterwards, the CBA can be investigated with the Grünbank App to decide about the loan grant. Finally, the access for Grünbank to the CBA is removed through the Ehrlich App with another adjustment of the ACL.
A video showing the proof of concept as a demo is available at https://purl.org/solid-poc-app/ demo. The repository of the developed Solid App is available on GitHub at https://github. com/wintechis/DATEV-Solid-PoC-App. The basic ontology used to model the RDF data of the accounting transactions and the CBAs is available at https://purl.org/solid-poc-app/ontology.
The proof of concept shows the usage of Solid in an enterprise loan request use case. With the usage of multiple Solid Pods as well as diferent identity providers and data backends, Solid displays its strengths to share data in an enterprise scenario while still keeping control over it.
Our next steps to advance the use case are additions to our technology stack besides the Solid specifications towards a mature solution for confidential enterprise data. These include features regarding data integrity, security against manipulation, confirmability of identities, and limits of authority. Another topic is more complex: the role/group hierarchies for access control.
Further possibilities lie in the automated processing of data from Solid Pods. The creation of the CBA in our use case could happen automatically whenever the accounting transitions are updated. Consequently, Grünbank could receive an automatic notification with access to the new CBA and automatically provide a fitting loan ofer to Nordwind using that data. Solid could thus work as an enabler for real-time economy.
Another application for Solid in the enterprise environment is automated data aggregation, e.g., in supply chains. With increasingly strict regulations, enterprises need to unfold their supply chains to the very bottom. To make statements about the sustainability of an entire supply chain, data must be aggregated vertically over multiple layers of suppliers.
Partially funded by the German Federal Ministry of Education and Research (BMBF) through the project “Velektronik” (FKZ 16ME0224). We currently continue with research mentioned in the outlook, funded by the BMBF through the project “MANDAT” (FKZ 16DTM107A).