SOAP Serialization

SOAP Serialization with C# and .NET

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In the previous post, we discussed binary serialization with C# and .NET. In this short article we are going to dive into some specific examples of use of the SoapFormatter class to SOAP serialize objects to XML and deserialize from XML back into objects.

We will discuss SOAP a little later in this article 🙂

SOAP Serialization with the SoapFormatter class

To get started, let’s create a simple class, add some attributes to help us control how properties are serialized, then we’ll serialize and deserialize the object.

To get started, let’s create a C# Console Application that we will call SoapSerializationSample.

Create the Soap Serialization Sample Console project
Create the Soap Serialization Sample Console project

Next, we will add a class to the project. We will call this class Sample.

Let’s now add two properties – Name and Value as shown below then decorate the class with the Serializable attribute.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace SoapSerializationSample
{
    [Serializable]
    public class Sample
    {
        public string Name
        {
            get;
            set;
        }

        public Int32 Value
        {
            get;
            set;
        }
    }
}

As you can see, this class is very simple and is a great starting point for examining SOAP serialization.

The Serializable attribute signals the .NET runtime that instances of this class can be serialized. To use serialization, this attribute must be in place at the class level.

Before we write the serialization code, let’s first add the references shown in the illustration below:

System.Serialization.Runtime References
System.Serialization.Runtime References

Next, let’s add the following using statements to our Program class:

using System.Runtime.Serialization;
using System.Runtime.Serialization.Formatters.Soap;

In our Program.cs class’s Main() method, we are going to write some simple code that uses the SoapFormatter to serialize an instance of our Sample object into a Soap XML stream.

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Formatters.Soap;

namespace SoapSerializationSample
{
    class Program
    {
        static void Main(string[] args)
        {
            //create an instance of our Sample class
            //which we will serialize below
            Sample sample = new Sample();
            sample.Name = "John Nelson";
            sample.Value = 44;

            //create a FileStream to accept the output
            FileStream fileStream = new FileStream(@"c:\temp\MySoapFile.dat", FileMode.Create);

            //create a SoapFormatter to serialize the object
            SoapFormatter formatter = new SoapFormatter();

            //serialize the object to the .dat file
            formatter.Serialize(fileStream, sample);
        }
    }
}

When we press F5 and run the application, the SoapFormatter serializes the Sample object to our MySoapFile.dat file. If we open this file in Visual Studio, we see something that looks like this:

SoapFormatter XML Output
SoapFormatter XML Output

So, some of you are probably looking at this output and screaming “this is NOT well-formed XML!” and you are right! This file does not contain an xml declaration does not contain opening and closing xml tags. Though an in-depth discussion of SOAP is well beyond the purpose and scope of this article, it will be beneficial to briefly discuss the parts of a SOAP message.

What is SOAP?

Soap is an acronym for Simple Object Access Protocol. It is basically an XML-based protocol for transmitting data between computers and is designed for for data communication via the internet and provides the transport mechanism for web services. SOAP is language and platform independent.

SOAP Message Structure

SOAP messages are encoded as XML documents. These documents begin with a mandatory <Envelope> element and may or may not contain a <Header> element. The <Body> element is mandatory for all SOAP messages, so we would expect to always see that. A <Fault> element may or may not be contained within the <Body> element and is used to provide information about exceptions or errors that may have occurred while the message was processed.

<Envelope> Element

The <Envelope> element is the start and end of the message. The entire SOAP message is contained within the <Envelope> element. Every <Envelope> element must contain exactly one <Body> element – no exceptions! The <Envelope> will change if the version of the message changes.

<Header> Element

<Header> elements are optional within the <Envelope> element and there can be multiple <Header> elements in a SOAP message.

<Body> Element

The <Body> element contains the actual data being transmitted in the SOAP message. You can think of it as the “guts” of the message or the payload of the message.

<Fault> Element

If you have ever worked with WCF, you are familiar with the FaultExceptions. When an error occurs during processing by a web service, information pertaining to that error can be encapsulated within a <Fault> block. If a <Fault> element is included in a SOAP message, there can only be one.

Learning More About SOAP

If you are interested in learning more about the SOAP standard, try this link.

Deserializing with the SoapFormatter

Deserializing with the SoapFormatter is as simple as serializing. See the code below:

//create a FileStream to open the .dat file
FileStream fileStream = new FileStream(@"c:\temp\MySoapFile.dat", FileMode.Open);

//create a SoapFormatter to deserialize the object
SoapFormatter formatter = new SoapFormatter();

//serialize the object to the .dat file
Sample deserializedSample = (Sample)formatter.Deserialize(fileStream);

//show the object properties
Console.WriteLine("The deserialized object:");
Console.WriteLine(String.Format("Name: {0}", deserializedSample.Name));
Console.WriteLine(String.Format("Value: {0}", deserializedSample.Value.ToString()));

Console.Read();

When we press F5 and run our application, we see the values of our object displayed in the console window:

SoapFormatter.Deserialize()
SoapFormatter.Deserialize()

Serialization with C# and .NET

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What is Serialization?

In the world of software development, serialization is the process of converting an object into a format that allows it to either be persisted (saved) to disk or memory, or to be transmitted across a network or over HTTP or TCP.

An object that has been serialized can be reconstructed later which is known as deserialization. I like to think of deserialization as the process by which we re-inflate the object back into its original state. If you think of an XML web service as an example, an application can be written using standard .NET objects, serialized as XML, passed around via HTTP or TCP, then deserialized (re-inflated) by the receiving application and used further.

In this article, we are going to take a quick look at three forms of .NET serialization and talk briefly about each. The following three articles will address XML serialization, binary serialization, and SOAP serialization and provide walkthroughs that give you an overview of how to implement each.

Serialization in .NET

The .NET Framework provides a few serialization mechanisms. Let’s discuss the three most well-known:

  • XML Serialization – serializes the public fields and properties of an object into an XML stream. XML serialization does not record or preserve information about the object’s original type or namespace. The .NET Framework provides a class called the XmlSerializer. This class provides methods with which we can serialize an deserialize objects.
  • Binary Serialization – serializes an object or an entire hierarchy of objects into a binary format. Binary serialization is a very efficient means of serializing .NET objects. The BinaryFormatter class offers numerous methods allow us to serialize and deserialize objects.
  • SOAP Serialization – serializes an object into XML, but also serializes private members. SOAP serialization does not support serialization of generic collections, but the SoapFormatter saves assembly and type information along with the data itself. SOAP serialization is ideal for communications between heterogeneous applications, or applications that are written using different architectures, languages, platforms, etc.

The decision as to which type to use is dictated by the needs of the application. For example, XML and SOAP serialization produce XML output which is usable across multiple platforms. Binary serialization in .NET should only be used in situations where the objects to be serialized and deserialized reside in namespaces that are usable and referenced by each application. If there is only one application in the discussion, then binary serialization will provide a speedy, compact form of serialization that will be quite suitable. So it comes down to considering performance, storage type and location, and extensibility.

See the table below for a high-level comparison of these three types of .NET serialization.

Comparison of XML Serialization, SOAP Serialization, and Binary Serialization
Comparison of XML Serialization, SOAP Serialization, and Binary Serialization

To use serialization in .NET, you essentially only need two things:

  1. A stream to hold or receive the serialized output
  2. A formatter (XmlSerializer, SoapFormatter, or BinaryFormatter) to fill the stream with output

As we mentioned earlier, XML Serialization utilizes the XmlSerializer class, binary serialization is provided via the BinaryFormatter, and SOAP serialization is handled by the SoapFormatter – .NET provides very rich support for serialization.

.NET Serialization Walkthroughs

The following posts will dive into the specifics of serialization with C# and .NET. Use the links below to select the appropriate post.

XML Serialization in C# and .NET

Binary Serialization in C# and .NET

SOAP Serialization in C# and .NET