## 3 CloudSera Features and Implementation
### CloudSera Features  
Since it is a cloud-based web application, CloudSERA does not require installation or configuration. It is available online for free usage [30]. Besides, CloudSERA is an open-source tool, with its source code openly released in GitHub [31]. Concerning the features of the non-functional category, the Grails framework has been used to develop the application. Figure 2 shows the conceptual information model managed by the tool. The user interface has been built using the Bootstrap toolkit, which provides a responsive and rich user experience. The tool is provided with development documentation and end-user tutorials. To summarize, the tool has been developed covering the complete set of non-function features, namely, it is cloud-based, open source and free, updated, not focused on a specific discipline, and delivered with user guides. Considering the overall category features, the tool has been implemented with a role management module, thus enabling users to collaboratively work on a review. Two main roles are defined, namely performer and supervisor. SR data can be shared among all the SR team members. With a user's consent, the SR data can be accessed through the \begin{table}
\begin{tabular}{l l l l l} \hline \hline
**Tool** & **Non-Functional** & **Overall Functionality** & **Information Management** & **Evidence Synthesis** \\ \hline CADIMA & 100 & 100 & 83.3 & 57.1 \\ Colandr & 100 & 100 & 50 & 57.1 \\ DistillerSR & 80 & 50 & 50 & 57.1 \\ EPI-Reviewer 4 & 60 & 75 & 33.3 & 57.1 \\ METAGEAR R & 80 & 50 & 0 & 42.8 \\ Rayyan & 100 & 75 & 33.3 & 0 \\ ReviewER & 40 & 50 & 33.3 & 0 \\ SESRA & 100 & 100 & 50 & 42.8 \\ SLR-Tool & 40 & 50 & 66.6 & 57.1 \\ CloudSERA & 80 & 75 & 100 & 14.28 \\ \hline
**Average** & **78** & **72.5** & **49.98** & **38.54** \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Percentage results of the comparison of available features in SR process support tools. web interface for preservation and reproducibility (see Figure 3b). Thus, users can follow other users' activities. Finally, CloudSERA provides a logging system to trace the actions performed by users in an SR project. To summarize, CloudSERA has been thought of, and built, to cover the main features of the overall functionality category, such as collaboration, user role management, data maintenance and traceability. Regarding the information management category features, users can create SRs and define research questions and related issues. CloudSERA can be used to automate several tasks of the SR process and includes a step-wise wizard (see Figure 3a) to guide users through the creation and configuration of an SR process. Besides, the tool automates the search tasks by launching the configured queries to an integrated set of databases and digital libraries. Currently, the supported sources are the following: ACM Digital Library, IEEE Computer Society, Springer Link and Science Direct. CloudSERA enables the inclusion of new sources easily through configuration. With the integrated search engines, the user does not have to run separate queries for each library. Every query runs asynchronously in the background and the user is notified when the search finishes. CloudSERA enables the definition of inclusion and exclusion criteria, which can be used to filter the bibliographic references found. References can be visualized and refined by means of a set of facets, according to the automatically retrieved metadata of the studies and the manually entered values for the attributes (see Figure 3c). These results will also be used to show the statistics of included and excluded studies, with their exclusion reasons. Considering the features of the evidence synthesis category, CloudSERA uses charts to visualize the data according to some aspects such as document type, language and inclusion or exclusion criteria, among others. Figure 3d shows an example of the main screen of a specific project. This enables users to report data results from the study inclusion/exclusion criteria and specific attribute tagging.