Extensible point-of-sale platforms and associated methods

1. A computer-implemented method for an extensible point-of-sale device, comprising:

registering an application, on the point-of-sale device, to be notified of a transaction change on the point-of-sale device;

displaying a user interface during a purchase transaction on a display of the point-of-sale device using one of a register module and a payment module;

receiving the transaction change via the user interface of the point-of-sale device;

broadcasting the transaction change to a set of registered applications, on the point-of-sale device, that includes the application; and

taking an action that modifies the purchase transaction using the application in response to the broadcasting.

2. The computer-implemented method for an extensible point-of-sale device of claim 1 , wherein:

the action comprises inserting an image onto a receipt printed for the purchase transaction by the point-of-sale device.

3. The computer-implemented method for an extensible point-of-sale device of claim 2 , wherein the action of inserting the image onto the receipt comprises:

transmitting the image to a services process on the point-of-sale device from the application; adding the image to the receipt using the services process; and

printing the receipt for the purchase transaction using the services process.

4. The computer-implemented method for an extensible point-of-sale device of claim 1 , wherein:

the action comprises inserting a text string onto a receipt printed for the purchase transaction by the point-of-sale device.

5. The computer-implemented method for an extensible point-of-sale device of claim 1 , wherein:

the action comprises displaying information on the display of the point-of-sale device.

6. The computer-implemented method for an extensible point-of-sale device of claim 5 , wherein the action of displaying information on the display comprises:

generating the information to display on the point-of-sale device using the application; and displaying, with the display of the user interface on the display, the information on an area of the display.

7. The computer-implemented method for an extensible point-of-sale device of claim 6 , wherein:

the application displays the information on the area of the display via a software component other than the register module or the payment module; and

one of the register module or the payment module concurrently displays transaction data along with the information on the area of the display.

8. The computer-implemented method for an extensible point-of-sale device of claim 1 , wherein:

the user interface is a first user interface, and

the action comprises inserting a second user interface on a payment window of the display of the point-of-sale device.

9. The computer-implemented method for an extensible point-of-sale device of claim 8 , wherein:

inserting the second user interface on the payment window of the display of the point-of-sale device is performed by the application; and

one of the register module and the payment module displays information on the display, with the display of the second user interface on the display by the application.

10. The computer-implemented method for an extensible point-of-sale device of claim 9 , wherein:

the user interface initiates a method of payment provided by the application.

11. An extensible point-of-sale device, comprising:

a POS processing service that registers an application, on the point-of-sale device, to be notified of a transaction change on the point-of-sale device;

a display that displays a user interface during a purchase transaction; and

a register module that receives the transaction change involving the purchase transaction via the user interface of the point-of-sale device;

wherein the application is configured to take an action to modify the purchase transaction in response to a trigger; and

wherein the POS processing service is configured to provide the trigger via a broadcast of the transaction change to a set of registered applications, on the point-of-sale device, that includes the application.

12. The extensible point-of-sale device of claim 11 , further comprising:

a printer that prints a receipt for the purchase transaction with an added image using the POS processing service on the point-of-sale device;

wherein the action comprises transmitting the added image to the POS processing service from the application;

wherein the transaction change generates a printing receipt event to initiate a printing process; and

wherein the trigger is the printing receipt event.

13. The extensible point-of-sale device of claim 11 , further comprising:

a printer that prints a receipt for the purchase transaction with an added text string using the POS processing service on the point-of-sale device;

wherein the action comprises transmitting the added text string to the POS processing service from the application;

wherein the transaction change generates a printing receipt event to initiate a printing process; and

wherein the trigger is the printing receipt event.

14. The extensible point-of-sale device of claim 11 , wherein:

the action comprises generating information to display on the display; and

the information and user interface are concurrently displayed on the display.

15. The extensible point-of-sale device of claim 14 , wherein:

the application displays the information on an area of the display via a software component other than the register module; and

the register module concurrently displays transaction data along with the information on the area of the display.

16. The extensible point-of-sale device of claim 11 , further comprising:

a network connection; and

a local database that stores the transaction change in a queue;

wherein the point-of-sale device is configured to transmit the transaction change from the queue via the network connection when the point-of-sale device is able to communicate with a server.

17. The extensible point-of-sale device of claim 11 , wherein:

the user interface is a first user interface; and

the action comprises inserting a second user interface on a payment window of the display of the point-of-sale device.

18. The extensible point-of-sale device of claim 17 , wherein:

inserting the second user interface on the payment window of the display of the point-of-sale device is performed by the application; and

the register module displays information on the display, with the display of the second user interface on the display by the application.

19. The extensible point-of-sale device of claim 18 , wherein:

the user interface initiates a method of payment provided by the application.

20. An extensible point-of-sale device, comprising:

a POS processing service that registers an application, on the point-of-sale device, to be notified of a transaction change on the point-of-sale device;

a display that displays a user interface during a purchase transaction; and

a payment module that receives the transaction change involving the purchase transaction via the user interface of the point-of-sale device;

wherein the application is configured to take an action to modify the purchase transaction in response to a trigger; and

wherein the POS processing service is configured to provide the trigger via a broadcast of the transaction change to a set of registered applications, on the point-of-sale device, that includes the application.

21. The extensible point-of-sale device of claim 20 , further comprising:

a printer that prints a receipt for the purchase transaction with an added image using the POS processing service on the point-of-sale device;

wherein the action comprises transmitting the added image to the POS processing service from the application;

wherein the transaction change generates a printing receipt event to initiate a printing process; and

wherein the trigger is the printing receipt event.

22. The extensible point-of-sale device of claim 20 , further comprising:

a printer that prints a receipt for the purchase transaction with an added text string using the POS processing service on the point-of-sale device;

wherein the action comprises transmitting the added text string to the POS processing service from the application;

wherein the transaction change generates a printing receipt event to initiate a printing process; and

wherein the trigger is the printing receipt event.

23. The extensible point-of-sale device of claim 20 , wherein:

the action comprises generating information to display on the display; and

the information is displayed on an area of the display along with the user interface.

24. The extensible point-of-sale device of claim 23 , wherein:

the application displays the information on the area of the display via a software component other than the payment module; and

the payment module concurrently displays transaction data along with the information on the area of the display.

25. The extensible point-of-sale device of claim 20 , further comprising:

a network connection; and

a local database that stores the transaction change in a queue;

wherein the point-of-sale device is configured to transmit the transaction change from the queue to a server via the network connection when the point-of-sale device is able to communicate with the server.

26. The extensible point-of-sale device of claim 16 , wherein:

the user interface is a first user interface; and

the action comprises inserting a second user interface on a payment window of the display of the point-of-sale device.

27. The extensible point-of-sale device of claim 26 , wherein:

inserting the second user interface on the payment window of the display of the point-of-sale device is performed by the application; and

the payment module displays information on the display, with the display of the second user interface on the display by the application.

28. The extensible point-of-sale device of claim 27 , wherein:

the user interface initiates a method of payment provided by the application.