POS solutions fall in to two main architectural categories.
"No Database" POS
Describes a light-weight and highly sophisticated POS solution that uses the power of a business platform (eg. Salesforce or NetSuite) to control its settings, customer data, product metrics and transactional information without having to constantly retrieve data from a central platform (slow).
By definition, a "No Database" POS means that the best of all worlds is achieved. There is no need to embark on expensive and risky integration initiatives.
"No Database" POS solutions are rare and focus on transactional speed, simplicity, up-time, functionality and a high-level of interoperability with other solutions.
SuitePOS is an example of a "No Database".
A "Database" POS has its own database and platform. The level and complexity of the database is directly in proportion to features these POS solutions try to offer beyond core functionality. For the most part, as a POS, they work just fine. However, in the real-world, things are a lot more complicated and less myopic.
Most mid-market companies have some form of ERP solution(s) that controls CRM, Marketing, Servicing, Warehousing (WMS), Inventory and Finance. This is where integration can become a bit un-realistic.
POS solutions generate customer and transactional data that needs to be accounted for and use product and customer data to generate the transaction. In other words, it is a bi-directional integration.
At the most rudimentary level, a "Database" POS operates within the framework of a closed and proprietary database where limited access is only granted by the API's that are available.
Bearing this in mind, if you are a small business, you could simply export the data and import it to the destination system. This is not scalable, very costly in terms of labor and error prone. It should never be undertaken.
You could use "Connectors" which describes middleware that moves data from one system to another. This is great, if the movement is linear; generally one direction; and fields and data structures map between one database and another. However, this is rarely the case.
Finally, you could write your own integration. This is very costly, risky and inflexible. In fact, it is likely to fail.
"Database" POS solutions are plentiful and should only be considered if you are a very small business.
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