Homemade vs. Java Serialization

Question

I have a certain POJO which needs to be persisted on a database, current design specifies its field as a single string column, and adding additional fields to the table is not an option.

Meaning, the objects need to be serialized in some way. So just for the basic implementation I went and designed my own serialized form of the object which meant concatenating all it's fields into one nice string, separated by a delimiter I chose. But this is rather ugly, and can cause problems, say if one of the fields contains my delimiter.

So I tried basic Java serialization, but from a basic test I conducted, this somehow becomes a very costly operation (building a ByteArrayOutputStream, an ObjectOutputStream, and so on, same for the deserialization).

So what are my options? What is the preferred way for serializing objects to go on a database?

Edit: this is going to be a very common operation in my project, so overhead must be kept to a minimum, and performance is crucial. Also, third-party solutions are nice, but irrelevant (and usually generate overhead which I am trying to avoid)

Answer 1

Elliot Rusty Harold wrote up a nice argument against using Java Object serialization for the objects in his XOM library. The same principles apply to you. The built-in Java serialization is Java-specific, fragile, and slow, and so is best avoided.

You have roughly the right idea in using a String-based format. The problem, as you state, is that you're running into formatting/syntax problems with delimiters. The solution is to use a format that is already built to handle this. If this is a standardized format, then you can also potentially use other libraries/languages to manipulate it. Also, a string-based format means that you have a hope of understanding it just by eyeballing the data; binary formats remove that option.

XML and JSON are two great options here; they're standardized, text-based, flexible, readable, and have lots of library support. They'll also perform surprisingly well (sometimes even faster than Java serialization).

Answer 2

You might try Protocol Buffers, it is a open-source project from Google, it is said to be fast (generates shorter serialized form than XML, and works faster). It also handles addition of new field gently (inserts default values).