Introduction to SOA.

Recently, due to the expansion of the system, it was found that the previous software was becoming increasingly difficult to maintain. Every time, the business manager told me the business process clearly,
I am explaining the relevant business processes to the programmers before development and maintenance can be conducted. The previous project manager did not leave any documents
I am going to clarify the business, write documents, and other things. I saw SOA on the Internet. Here I will talk about my understanding of SOA.
SOA is actually an architecture. The concept can be found on many websites and won't be stuck here. According to my understanding of SOA
A program is divided into multiple services to process different services. For example, a company has two departments: Finance Department and business department.
As before, we will create a data operation layer, a business layer, and a presentation layer (the simplest three layers). For example:

Figure 1
The demand was raised, because we need to outsource the operations of the finance department to one company, and the operations of the business department to another company. For example:

Figure 2
The problem arises where the two companies are implicated, and system integration is required. According to the previous practice, everyone will sit together to discuss the DLL interface, and then go back to the development.
Time System Integration. Let's sit together and discuss the new DLL interface, and go back to development... Okay. The problem is solved.
The demand was raised again. The company's Reform set up the finance department as a company and the business department as a company, which completely separated the finance and business.
The company does not want some of my materials to be known to the Business Company, and the Business Company does not want some of their materials to be known to the financial company. Therefore, we cannot create
Software.
SOA proposes a solution. The finance company develops its own software to provide the service interface, and the Business Company develops its own software to provide the service interface. If the finance company wants
You only need to access part of the business data directly to the Service Interface proposed by the Business Company. The same applies to the Business Company. 3:

Figure 3
The problem is solved. If the Business Company is bigger, then the second and third companies are separated, we will not be afraid. We only need to access the corresponding financial interface to solve all the problems.
Finally, follow the passage of relevant experts on the Internet: SOA is an IT architecture style that allows you to integrate your business as a link service or reusable business tasks, you can access these services and tasks through the network as needed.
I can only understand so much about my younger brother's knowledge. Hope you can understand it. Thank you!