What is the difference between Serialization and Marshalling?

Question

I know that in terms of several distributed techniques like RPC the term Marshalling is used, but I don't get the difference with Serialization. It both is transforming objects to series of bits no?

Related:

What is Serialization?

What is Object Marshalling?

Answer 1

I think that the main difference is that Marshalling supposedly also involves the codebase. In other words, you would not be able to marshal and unmarshal an object into a state-equivalent instance of a different class. .

Serialization just means that you can store the object and reobtain an equivalent state, even if it is an instance of another class.

That being said, they are typically synonyms.

Answer 2

From the Marshalling (computer science) Wikipedia article:

The term "marshal" is considered to be synonymous with "serialize" in the Python standard library[1], but the terms are not synonymous in the Java-related RFC 2713:

To "marshal" an object means to record its state and codebase(s) in such a way that when the marshalled object is "unmarshalled", a copy of the original object is obtained, possibly by automatically loading the class definitions of the object. You can marshal any object that is serializable or remote. Marshalling is like serialization, except marshalling also records codebases. Marshalling is different from serialization in that marshalling treats remote objects specially. (RFC 2713)

To "serialize" an object means to convert its state into a byte stream in such a way that the byte stream can be converted back into a copy of the object.

So, marshalling also saves the code of an object in the byte stream in addition to its state.

Answer 3

Marshalling is usually between relatively closely associated processes; serialization does not necessarily have that expectation. So when marshalling data between processes, for example, you may wish to merely send a REFERENCE to potentially expensive data to recover, whereas with serialization, you would wish to save it all, to properly recreate the object(s) when deserialized.

Answer 4

Marshaling and serialization are loosely synonymous in the context of remote procedure call, but semantically different as a matter of intent.

In particular, marshaling is about getting parameters from here to there, while serialization is about copying structured data to or from a primitive form such as a byte stream. In this sense, serialization is one means to perform marshaling, usually implementing pass-by-value semantics.

It is also possible for an object to be marshaled by reference, in which case the data "on the wire" is simply location information for the original object. However, such an object may still be amenable to value serialization.

As @Bill mentions, there may be additional metadata such as code base location or even object implementation code.

Answer 5

Think of them as synonyms, both have a producer that sends stuff over to a consumer... In the end fields of instances are written into a byte stream and the other end foes the reverse ands up with the same instances.

NB - java RMI also contains support for transporting classes that are missing from the recipient...