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The main features and key characteristics of SOA are described below so that the readers can easily understand the real use of SOA in cloud computing and why the SOA characteristics are combined with cloud architecture.

 Black-box component concept in SOA: The main feature of black box is reusability of existing business applications. When the developers are mounting new applications, they feel free to reuse the advantages of existing applications; black box is simply adding adapter to them. The service consumers don’t really need to be on familiar terms with the details of what is going on inside each component. SOA hides the underlying structure and the complexity.

 Loose coupling: Previously, in traditional structure, the different software components are extremely dependent on each other and that makes the applications more complex and time-consuming. A bit change on one component makes lots of changes in others. So, to make the applications more feasible to the customers, the components of SOA have been made loosely coupled, which is the independent modular approach which makes the developer feel free to keep the software modules together and reuse them according to the needs of the user. Loosely coupled components can interchange the data between them after processing. One component does its task and passes the data to another neighboring component which carries out the job and either keeps the data or passes on the data accordingly. You might be a bit confused regarding the software module. What is a software module? How is it used? How can it be reused? However, we will consider an example so that we can understand the concept of software module. Software module is nothing but a collection of coding. If users want to access resources from their service provider, they make a request to the provider. The provider handles the request and gives permission. So, there is a need for authentication and authorization. This is done with a coding component. This code can be done in an application-specific or independent coding way. The latter is more useful because we can use this type of independent coding as a software module and with some modification of this coding module we are able to reuse that component.

 Service-oriented architecture: SOA supports an environment where different components are arranged in such a way that SOA is able to deliver a business service. While designing SOA service, developers incorporate some service-level agreements (SLA) so that a standard platform can be built for business management. This is called business process management (BPM). BPM is highly required to maintain the alignment of business service.