The NoSQL Cache System

MonaServer provides you with the ability to save data in a NoSQL way.

The data global variable

data is the name of the global table variable that performs read&write on the disk.

Writing persistent data

To write data in the database just assign the table data.

function onConnection(client, ...)
    data["lastClientId"] =

    -- save each client connexion time in a table
    if data["clientsConnexions"] == nil then data["clientsConnexions"] = {} end
    data["clientsConnexions"][#data["clientsConnexions"]+1] = os.time()


If you want to delete some old value (or entire database) you just have to affect nil to the corresponding key like this :

function clearLastClientId()
    data["lastClientId"] = nil


  • You can use the pairs() LUA function to iterate on data or any subarray of data.
  • And the “#” operator to get the number of elements (it’s an exception where objects properties are counted in the array size).
  • If you want to delete an object or table you must delete all childs one by one (you can make a function) because only primitive values are deleted on the disk.


You must notice that each number in data is converted into a string, so you could have to use tonumber for further use.

Reading persistent data

To access to a data value it is as simple as this :

function onMessage(message)
    NOTE("Last client ID : ", data["lastClientId"])

How does it works?

This system permits fast data retrieving and does not allow data corruption as it use md5 for integrity checking.

Root application’s values (www) are stocked in the data directory and all sub-applications have their own sub-directory. With this thing in mind you can access to sub-applications’s data in each parents applications :

function onConnection(client, ...)

    if data["subapp"] then INFO("sub data sample : ", data["subapp"]["sample"]) end

And respectively you can access to parents’s data using the keyword super :

function onConnection(client, ...)

    INFO("parent data : ",["parentValue"])


The entire database is readed at MonaServer’s start so you must take care of memory limits.