Writing Data (POST Method)

To store data on the server, you must send an HTTP POST request with URL-encoded form data. The MIO Server accepts parameters like folder name, file name, and message content.

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Required Parameters

Parameter	Description
key	Password defined in config.ini (password=...)
token	Folder name where the file will be stored
file	Filename to save the data into (within the token folder)
message	Content of the message (plain text or CSV data, etc.)

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Optional Parameters

Parameter	Description	Default
mode	overwrite or append (controls file write behavior)	overwrite

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Example cURL Command

curl -d "key=public&token=device01&file=data.txt&message=Hello+world" http://localhost:9123

To append a new line to an existing file:

curl -d "key=public&token=device01&file=data.txt&message=Another+line&mode=append" http://localhost:9123

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Error Responses

HTTP Code	Meaning
403	Invalid or missing key
413	Message too large
400	Malformed request
500	File write error on disk

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File Structure

Files are stored in:

[serverpath]/[token]/[file]

For example:

./db/device01/data.txt

Each token becomes a folder. Files inside will be either created new or appended depending on mode.

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📝 Notes

• Message size must not exceed maxmessage defined in config.ini
• If the folder or file does not exist, it will be created
• message should be URL-encoded (e.g., spaces = +)
• mode=append automatically adds a \n newline after each message (if not present)