# A Survey from Real-Time to Near Real-Time Applications in Fog Computing Environments
## 2 Material and Methods
### Research Methodology
#### 2.2.3 Analysis of Results  
The analysis of results can be divided into two stages: quantitative analysis and classification of articles according to similar characteristics. In the first stage, we present some metrics based on the characteristics of the articles as follows: number of articles published over of the years, country of the first author, and number of articles published by publishers. We can see in Figure 3 that publications began in 2015 and had a gradual increase, having its apex in 2018 with 33 articles published. Countries such as China (20), the United States (10), and India (9) had the highest number of publications, as shown in Figure 4. For this analysis, we consider the country of the first author of the article. Figure 3: Publications separated by year. Figure 2: Search protocol fluxogram. Regarding publishers, we separate articles according to the years and types of articles that publishers have most published. As we can see in Figure 5, IEEE had a higher amount of publication every year compared to other publishers. However, it obtained the highest number of publications in 2017 (23), followed by ACM, with four publications in 2018 and Elsevier with four in 2019. In 2019, Elsevier showed an increase in the number of publications compared to IEEE. Table 1 presents the number of publications by type and publisher, considering articles published in the journal (article) and articles published in event annals (inproceedings). As we can see, there are more congress publications, but it is not a significant difference since inproceeding articles have 53% of journal publications and 47%. Figure 4: Publications separated by country. Figure 5: Publications by year and publisher. With the reading of the articles, we have identified a pattern in the way real-time concepts are applied to research. With the identification of this pattern, we classified the articles according to the proposal and the application of the real-time concept in the research. With that, we carried out the second stage of the analysis of the results. The proposed classification is divided into five categories, which are:  
* Fog Computing Concept: articles belonging to this category associate real-time to the concept of fog computing. When [PERSON] et al. [3] presented fog computing, they attributed, as one of its main features, the possibility of the architecture to execute applications in real-time. In other words, these articles did not present in their proposals' time constraints on application execution or data presentation. * Low Latency: articles in this category associate low latency with real-time systems. In other words, these articles propose solutions that improve latency and response time rather than time-constrained proposals. Latency, in turn, is the system delay in processing the request. * Fast Response: articles in this category present understanding that a real-time system responds quickly or instantly. The authors do not have any system response time or deadline constraints, only the improved average response time. Response time, in turn, is the time that the system takes to perform the processing and send the response. * Data Streaming Applications: articles belonging to this category relate the concept of real-time with data streaming applications. Due to characteristics such as speed and continuous data sending, the authors understand that this type of application performs its tasks in real-time. * Time, Latency, or Delay Constraint: in articles belonging to this category, the authors proposed time, delay, or latency constraint and understand that the proposed solutions should execute within a time limit or meet an acceptable delay rate. From the classification of articles by categories, we performed analyses for information such as publication year, country's first author, publishers, and the applications used in the proposals. Table 2 shows the number of articles published by publisher and category.