I'm looking for an efficient and secure way to store small amount of user data like a line of text, for an indefinite period of time. The scenario: One client 'A' sends some data to another client 'B' , asynchronously via a server 'S'. For simplicity, consider the data to be a single line of text. Now, this data would be delivered to client 'B' by server 'S' , only when B asks for it. So until that time Server 'S' has to store this data.
For a simple demo, I implemented it very crudely as follows:
Client 'A' does a POST request with XMLHttpRequest, sending the text to 'S' as follows
xhr.open("POST",url+"?sentText=text"); //url points to a php file on S
xhr.send();
The PHP code then saves the received text to a file as follows:
<?php
$selected = $_GET["sentText"];
$writefile = "text.txt";
$fh = fopen($writefile,'w');
fwrite($fh,$selected);
fclose($fh);
?>
Later, after any amount of time, B asks for the text in this file,using BufferedInputStream as follows:
URL fileurl = new URL("url/text.txt");
BufferedReader in = new BufferedReader(new InputStreamReader(fileurl.openStream()));
while((tmpReceived = in.readLine())!=null){
received = tmpReceived;
}
This demo works properly, but this is just a demo. However, if this were to be a full scale real world application with millions of users, how would I implement the following:
The part where server S stores the text. Obviously, I can't save the text as plain text in a file, as it would breach my users' privacy. And it would also be ineffecient when there are millions of users. How do commercial services like Dropbox achieve this?
To keep things simple, I just need to know how to do this for text, then I can extrapolate to other types possibly.
Thanks a lot!
