# Digital Cloud Environment: Present Challenges and Future Forecast
## 3 Basic GCC Architecture Models and Cyber Security Issues  
Big international IT companies have similar globally distributed infrastructure and provide cloud services in multiple geographic regions worldwide [16; 17] (Figure 1). A region is usually named by a three letter abbreviation of the nearest international airport, for example SJC--San Jose California, USA; YYZ--Toronto's main airport, Canada; AMS--Amsterdam, the Netherlands, SIN--Singapore; SYD--Sydney, Australia, etc.  
Every region is built of at least two data centers (DCs)--a primary unit and a standby one (Figure 2). Such redundancy is designed for the purpose of workload switchover in case of a local incident or an entire DC outage. Each unit supports a certain part of data (POD), including client account database (ADB) and a set of cloud service applications interconnected with the shared message system storage (MSS) for storing call prompts, DB queries, application logs, and other system events. Regular replication of ADB data between the DCs is configured to perform a switchover faster when initiated. For example, RingCentral International Telecommunications Company uses Oracle as a DB and Golden Gate as a third-party solution for optimized ADB synchronization based on triggers and data transaction logs [18].  
To build a cloud IT environment, the three basic architecture models are practically used--private (on premises), public, and hybrid (Figure 3). On premises, the entire IT infrastructure is allocated  
Figure 1: Typical globally distributed cloud computing (GCC) infrastructure and data flows.  
Figure 2: Example of regional GCC architecture with two data centers (DCs) [18].  
in corporate DCs, giving full control over computing resources. Public cloud solutions allow IT companies to exclude the expenses for maintaining their own DCs. A hybrid cloud is an integrated solution with an attempt to inherit the advantages of both private and public models.  
The key trend of GCC popularity among people and IT companies in the world is moving from private towards public clouds. Microsoft and Gartner analytics compiled in Table 1 shows that the growth of all public cloud services almost doubled over the last five years [19; 20].  
The advantages of the public cloud are obvious:  
* Significant decrease of IT expenses for maintaining DCs on premises
* Minimize the IT department to support end users
* Low level of IT personnel skills required
* Flexible scalability of cloud computing resources and capacity planning
* Support IT services related to backups, disaster recovery, etc.  
In spite of the big benefits, the public cloud technologies have certain challenges, and cyber security is one of them. Personal sensitive information is stored on the external public network maintained by a vendor and is transferred via common internet channels. Tokenization of secret information, data encryption during transfer, and other approaches [1] are good ways to reduce the risks. The other threats associated with the public cloud are shown in Table 2.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**World Market, \$ billion** & **2016** & **2017** & **2018** & **2019** & **2020** \\ \hline Software as a Service (SaaS) & 38.57 & 46.33 & 55.14 & 64.87 & 75.73 \\ Platform as a Service (PaaS) & 7.17 & 8.85 & 10.62 & 12.58 & 14.8 \\ Infrastructure as a Service (IaaS) & 25.29 & 34.6 & 45.56 & 57.9 & 71.55 \\ Load Balancer as a Service (LBaaS) & 90.26 & 104.52 & 118.52 & 133.57 & 151.1 \\ Database as a Service (DBaaS) & 40.81 & 43.77 & 47.56 & 51.65 & 56.18 \\ IT Security & 7.15 & 8.77 & 10.43 & 12.16 & 14 \\ \hline Total & 209.24 & 246.84 & 287.82 & 332.72 & 383.36 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Gartner analytics of growth trend for main cloud services.  
Figure 3: Basic cloud architecture models.