Serialization is the process of converting an object’s state (including its references) to a sequence of bytes, as well as the process of rebuilding those bytes into a live object at some future time. Simple……Coverting an object to bytes and bytes back to object. So when is serialization used? Serialization is used when you want to persist the object. It is also used by RMI to pass objects between JVMs, either as arguments in a method invocation from a client to a server or as return values from a method invocation. In general, serialization is used when we want the object to exist beyond the lifetime of the JVM.
Lets see couple of different scenarios (examples) where we use serialization.
- 1. Banking example: When the account holder tries to withdraw money from the server through ATM, the account holder information along with the withdrawl details will be serialized (marshalled/flattened to bytes) and sent to server where the details are deserialized (unmarshalled/rebuilt the bytes)and used to perform operations. This will reduce the network calls as we are serializing the whole object and sending to server and further request for information from client is not needed by the server.
- 2. Stock example: Lets say an user wants the stock updates immediately when he request for it. To achieve this, everytime we have an update, we can serialize it and save it in a file. When user requests the information, deserialize it from file and provide the information. This way we dont need to make the user wait for the information until we hit the database, perform computations and get the result.
Here are some uses of serialization
- To persist data for future use.
- To send data to a remote computer using such client/server Java technologies as RMI or socket programming.
- To “flatten” an object into array of bytes in memory.
- To exchange data between applets and servlets.
- To store user session in Web applications.
- To activate/passivate enterprise java beans.
- To send objects between the servers in a cluster.