Tutorial for building RPG in-game market

I built a mobile RPG game a month ago and I have already implemented a few online features using Firebase, such as login, cloud save and invite system. Now I am working on adding a market for players to trade equipment and items they gathered inside the game, and this feature seems to be a bit challenging to implement.

The market should be able to let players to put items for sale, search for items to buy and sort the result. The screenshot below from the game Nostale is pretty much what I have in mind.


The logistics of the market function can be easily implemented with a database, but I have concerns regarding the scalability of the function. I want to ensure the game can withstand a lot of players while minimizing the number of read and write, as well as the cost for the cloud service to maintain the game.

I have done some research online but I found no tutorials for implementing similar online system. Does anyone have idea on where should I start?

 

Hello,
have you already found a solution here that would interest me.

 

I am working on building a massively scalable trading solution for something else, but I think it could apply to multiplayer games as well. The problem is I don't know much about how game servers work.

My solution would give you access to an API that allows you to place sell or buy orders, you would be able to see available trade offers and a history of prices per item. Over time the system would have some complex trading features that would allow you to build a very solid marketplace. Think EVE Online (and beyond) levels of functionality.

When two players are matched for buy-sell the trading system would be able to call an API on your end and would pass the details of the completed transaction. For example: action 1 - subtract 150 gold from player 150, action 2 - add Excalibur item to player 254 (this would be encoded in JSON, or other format, obviously)

Would such a system work for your games? Could you integrate with it?