  In managed languages, serialization of objects is typically done in bespoke
binary formats such as Protobuf, or markup languages such as XML or JSON. The
major limitation of these formats is readability. Human developers cannot read
binary code, and in most cases, suffer from the syntax of XML or JSON. This is
a major issue when objects are meant to be embedded and read in source code,
such as in test cases. To address this problem, we propose plain-code
serialization. Our core idea is to serialize objects observed at runtime in the
native syntax of a programming language. We realize this vision in the context
of Java, and demonstrate a prototype which serializes Java objects to Java
source code. The resulting source faithfully reconstructs the objects seen at
runtime. Our prototype is called ProDJ and is publicly available. We experiment
with ProDJ to successfully plain-code serialize 174,699 objects observed during
the execution of 4 open-source Java applications. Our performance measurement
shows that the performance impact is not noticeable.
