## 3 The Proposed Data Integration Approach for Agricultural Open Data Platforms
### Web Services and Exportation (WSE)  
The open-data platforms can publish data in different formats. The proposed approach allows users to choose directly downloadable and web service options considering the heterogeneity of applications, which use the published data. The platform users can export linked open data, which are created by mapping agricultural ontology classes with data gathered from IoT devices in varied file formats such as XML, JSON, HTML, CSV, Excel spreadsheets, RDF/XML, RDF/JSON, N-triples, Turtle and Notation 3. Table 2 gives a brief overview with respect to these data formats. On the other hand, data can also be published through web services in XML and JSON formats. Consuming web services to process data requires relatively less effort than semantic web technologies. However, in the open-data world, it is indispensable to publish data in open-data formats. Software applications, which are designed and developed for stakeholders in agriculture domain, can use published data through open-data platforms. Software applications handling published data may be a desktop application, web application or mobile application. A major problem with this software applications' heterogeneity in terms of utilizing published data are that there needs to be a mechanism which provides suitable data formats for each type of software applications. The proposed approach seeks to come up with developing XML web services, REST web services and Web APIs which help to address and provide robust and effective solutions for data type \begin{table}
\begin{tabular}{c c c c} \hline \hline
**File Format** & **Abbreviation** & **Mime Type** & **Description** \\ \hline eXtensible markup language & XML & text/xml & \begin{tabular}{c} Software and hardware independent for \\ sharing data between different \\ applications [50] \\ \end{tabular} \\ \hline JavaScript object notation & JSON & application/json & \begin{tabular}{c} Frequently used lightweight format for \\ sharing and storing data [51] \\ \end{tabular} \\ \hline Hypertext markup language & HTML & text/html & \begin{tabular}{c} Standard markup language for Web \\ pages [52] \\ \end{tabular} \\ \hline Comma-separated values & CSV & text/csv & \begin{tabular}{c} A type of data file which separate \\ values using comma \\ \end{tabular} \\ \hline Excel spreadsheet & Excel & \begin{tabular}{c} application/ \\ vnd.ms-excel \\ \end{tabular} & \begin{tabular}{c} Stores data into rows and columns, \\ provides powerful analyzing \\ capabilities and calculating operations \\ \end{tabular} \\ \hline Resource description framework & RDF/JSON & application/json & \begin{tabular}{c} An RDF graph to be written in a form \\ compatible with JSON [54] \\ \end{tabular} \\ \cline{2-4}  & N-triples & \begin{tabular}{c} application/ \\ n-triples \\ \end{tabular} & \begin{tabular}{c} A line-based, plain text format for \\ encoding RDF graph [55] \\ \end{tabular} \\ \cline{2-4}  & Notation 3 & text/n3 & \begin{tabular}{c} An assertion and logic language, \\ superset of RDF [56] \\ \end{tabular} \\ \hline \
\begin{tabular}{c} Terse RDF triple \\ language \\ \end{tabular} & Turtle & text/turtle &
\begin{tabular}{c} An RDF graph to be written in a \\ compact and natural text form [57] \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Data formats used for the proposed approach. compatibility issues among software applications. In addition, web services, particularly RESTful web services, can help solve interoperability problems by allowing software applications running on different platforms to request, access and manipulate data, which can be easily processed. Interoperability between software applications is not only a problem for applications that run on different platforms, but also on the same platform as well. Therefore, the proposed approach strongly recommends developing REST web services, Web APIs or both. Another service of the proposed approach is Reporting Service, which enables us to create and manage well-designed data reports.