The product is a local windows program "POSconnect" that interacts between:
1. A web application
2. A tax control unit (locally connected as COM port via USB)
3. A card payment terminal (connected via TCP / IP in local area network with fixed IP number to the computer, and connected to the bank via the internet)
4. A printer
The web application is a Point-of-Sale system (hereinafter referred to as POS). The user registers products, prices and customer, then completes the sales transaction when the user presses the PAY button and selects payment mode.
The POS program communicates with the POSconnect application. The feed is fed via an XML url with posted replies to a URL specified in settings.
Then the following happens if the user selected CREDITCARD as payment method:
1. Total amounts, items, prices and customer are written in the XML table
2. The POSconnect program regularly reads the XML table and sees that the table is updated, after which the POSconnect application activates the card terminal through a dynamic link library (DLL).
3. The terminal then carries out a card purchase against the bank.
4. The purchase can then be approved or rejected by the bank.
5A. If the purchase is rejected by the bank:
I. POSconnect posts the result to URL and is ready for a new transaction.
II. POSconnect logs the activities
5B. If the purchase is approved by the bank:
I. POSconnect posts the result to URL
II. POSconnect asks the tax control unit for a "control number" (a serial number that the tax control unit creates). Then, control number is sent together with all transaction data to the tax control unit which saves them in its memory.
III. POSconnect prints the control number on the receipt together with the other receipt information.
IV. POSconnect logs the activities
All activity is logged in a file that is readable to the human eye.
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i am a lead .NET software engineer and responsible for creating a web and desktop applications using different languages and technologies if u r interested just send me a message thank you and good luck