Recent years have shown many developments in the direction of immutable and distributed storage. One of them was the development of blockchain databases. These systems combine blockchain and database features while trying to remain competitive. Some of these systems are similar to traditional databases by supporting Structured Query Language (SQL) like language or using traditional databases as storage. Nevertheless, there is no general interface for blockchain databases. A missing general interface in blockchain databases leads to a steep learning curve and requires custom solutions with high maintenance costs. While typical databases have standardized properties such as SQL they greatly benefit from Object Relational Mapping (ORM) to reduce development and maintenance costs. This thesis investigates if an extendible ORM solution based on code generation is feasible for blockchain databases. Additionally, we discuss the advantages and disadvantages of using a blockchain-based system as general-purpose storage. This thesis investigated multiple blockchain database storage options, as the properties highly depend on the underlying storage system and the communication between the components (i.e., consensus). As proof of concept, this thesis implements two blockchain database showcases for our Smart Contract Object Mapping (SmartCOM) framework. SmartCOM proposes a general-purpose storage architecture supporting Create Read Update Delete (CRUD) and trace capabilities for both showcases. The two showcases are then compared against each other and vaguely to similar state-of-the-art frameworks. As a result, these showcases are interchangeable. Additionally, SmartCOM is extendible for further blockchain storage options. With SmartCOM, users can already store data on two different blockchain databases without blockchain programming knowledge or writing platform-specific code.
