A Middleware acts as a sandwich between systems , In any organization data whether its an employee , vendor or clients data is stored using a form. Backend is a database which stores the content entered into form. But before inserting or retrieving the data into/from database some data needs to processed , the required processing is done by middleware.
Middleware is nether part of Application or Database , It acts as a processing engine. In the diagram middleware is acting as a bus/carrier which takes your data and save it in the database.
There are various middleware tools available in the market. Here we will see an overview the middleware tool which is provided by SAP.
SAP PI is the EAI middleware tool. EAI means Enterprise Application Integration middleware tool.Middleware tool can be used for various purposes. If a middleware tool is used in an enterprise to support its business, it is termed as EAI.
Now in an enterprise or a company, we have HR department, Finance department, Sales department, Account department etc. All these above departments may save data in different format. So we need a tool which converts the data format for each of the above department. SAP PI does that. It accepts data in available format from a Sender System, and save the data in the required format of the target system and vice versa.