Related work

This section is broken into two parts: the first provides an overview of existing data models and standards used in the context of disaster recovery (Section 2.1), and the second reviews current DR systems in terms of security (Section 2.2) and semantic interoperability features (Section 2.3). (Section 2.3). Table 1 summarizes the various characteristics of the DR systems studied.
DR data models and standards
Several DR efforts have been presented that provide support for various features of data in terms of formats and models in the DR domain. Some standards have been developed that give XML data scheme models. Energy Market Information Exchange (eMIX [24]) is a pricing and product standard. The Universal Smart Energy Framework (USEF [25]) encourages the commoditization of flexible energy consumption through flexible markets. The Ope- nADR standard [26] is another well-known endeavor that conceptualizes DR through a data and communication definition.
Other DR attempts, such as EN 50090-1 [27] and the IEC family of standards, provide generic data models in UML without requiring a specific data format (CIM [28], 62056 COSEM [29], 62746 [30]). Furthermore, the Smart Grid Architecture Model (SGAM [31]) outlines the architectural design of smart grid use cases, with five levels representing business objectives and processes, functions, information exchange and models, communication protocols, and components.
Finally, several DR projects give data models in the form of ontologies. These ontologies are mostly concerned with modeling energy-related data, while some, such as the OpenADR ontology [4] and the DELTA ontology [21], also deal with DR. On the one hand, several of these ontologies are concerned with modeling measurements (OntoEnergy [32]) or measurements and equipment (CIM ONTOLOGY,7 MAS2TERING [33], ThinkHome [34]). There are, on the other hand, ontologies that include other topics, such as events (MI- RABEL [35]) or geolocation (BOnSAI [36], SEMANCO,8 SESAME9).
Finally, other ontologies such as SAREF4ENER,10 MAS2TERING [37], EEPSA [38], RESPOND,11 SARGON [39], and OEMA12 are intended for stakeholders involved in smart grids and energy-related enterprises.
As a result, the DR has a diverse set of standards that rely on various types of data models and accompanying data formats, resulting in a heterogeneous data environment. When data is transmitted between DR systems that adhere to various standards, this circumstance displays an obvious technological barrier. This challenge is exacerbated by the fact that not all standards can model the same type of data, and hence relying on several standards may become necessary. To address this issue, a semantically compatible DR solution that enables transparent data consumption independent of the model and format in which it is expressed is required.
Table 1 Comparison of existing DR proposals.