What does Serializing a graph mean?

I have seen this expressio开发者_如何学JAVAn "Graph Serialization" in so many places. what does it mean? And what does serialization mean in general and when it is used or in which domains it is mentioned?

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Serialization is the process of turning a data set into binary data for transmission or storage. On the iPhone for example, we do this:

NSString *myStringToSerialize = @"I'm going to be bits!";

NSData *data = [myStringToSerialize dataUsingEncoding: NSUnicodeStringEncoding];

The data object is now a binary representation of myStringToSerialize, that we can do something with it (POST it to a web server, save it to a file, email it, etc...).

Graph Serialization is when you take the graph structure and write it to bits so that you can send it somewhere and read it again.

We normally serialize for two reasons:

1) Serialization provides:

• A method of persisting objects which is more convenient than writing their properties to a text file on disk, and re-assembling them by reading this back in.

• A method of issuing remote procedure calls, e.g., as in SOAP

• A method for distributing objects, especially in software componentry such as COM, CORBA, etc.

• A method for detecting changes in time-varying data.

2) Serialization allows us to transfer objects between programming languages and various systems that would not be interoperable without serialization.

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Serialization is used to flatten a complex structure in something that can be easily transmitted or stored. Every application uses objects that can represent a functional structure (List, Tree, Graph).

But problems come when you have to use them outside your application. How for instance, will you save your fabulous customer list once your edited it ? How can you provide a temperature graph through a web-service. Think something about putting them in a linear structure, like an array of bytes or a string or a database field.

For example, xml file is the result of serializing a tree.

Graph serialization is about serializing graphs. The big issue with this type of content, they are harder to crawl. Unlike trees, you can loop through nodes ; they are harder to represent them in a linear way.