WCF Message Size Reduction Techniques

Want to speed up your WCF services? Here's how to shrink those bulky messages:

1. Use better data contracts: Short names, flat structures, no unused fields
2. Pick efficient serialization: DataContractSerializer beats XMLSerializer
3. Compress messages: Enable GZIP compression
4. Go binary: Use binary encoding instead of text
5. Break it down: Send data in smaller chunks, use paging
6. Optimize XML: Remove whitespace, use short element names
7. Stream large files: Don't embed big data, use streams instead

Quick Comparison:

Technique	Pros	Cons
Data contracts	Significant size reduction	May affect readability
Compression	Huge size reduction	Slight processing overhead
Binary encoding	~50% size reduction	Less human-readable
Streaming	Handles large files well	Requires different programming model

Remember: Always measure before and after to track your gains. There's no one-size-fits-all solution, so test what works best for your specific WCF app.

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Parts of a WCF message

To shrink WCF messages, let's break them down:

Message structure

WCF messages use SOAP, with three main parts:

1. Envelope: Wraps everything
2. Header: Holds metadata
3. Body: Contains the actual data

Here's a quick look:

Component	Purpose	Size Impact
Envelope	Message wrapper	Tiny
Header	Metadata storage	Varies
Body	Main content	Biggest

The body's usually the chunkiest part, but headers can bulk up too if they're packed with info.

XML format

WCF messages use XML, which is readable but bulky. Why?

• Double tags for each element
• Named attributes
• Extra spaces and line breaks

Check out this XML example:

<Person>
  <FirstName>John</FirstName>
  <LastName>Doe</LastName>
  <Age>30</Age>
</Person>

It's 82 bytes for just 11 bytes of data. That's 645% bigger!

Now imagine sending 1000 people - you'd add about 71KB of XML fluff.

WCF's default size limits are tight:

Limit	Size
Max message	64KB
Max buffer	64KB

With these caps, you could hit the limit with just a few hundred records.

Knowing these parts helps you slim down your messages. Focus on trimming the XML and body data to boost your WCF app's performance.

Causes of large messages

WCF messages can get big. Here's why:

Verbose XML

XML is readable but bulky. It uses:

• Double tags
• Named attributes
• Extra spaces

Look at this person object in XML:

<Person>
  <FirstName>John</FirstName>
  <LastName>Doe</LastName>
  <Age>30</Age>
</Person>

It's 82 bytes for 11 bytes of data. That's 645% bigger!

Extra data

Messages get fat with:

• Unused fields
• Redundant info
• Long error messages

Bad data contracts

Poor design leads to:

• Nested objects instead of flat ones
• Repeating info
• Inefficient data types

Large binary data

Sending files bloats messages:

• Images
• Videos
• Big documents

WCF uses Base64 encoding, making files 33% bigger. A 500 MB file becomes 665 MB.

Data Type	Original	Base64 Encoded	Increase
Text	1 KB	~1.37 KB	37%
Image	5 MB	~6.67 MB	33.4%
Video	500 MB	~665 MB	33%

To fix this:

1. Optimize XML
2. Cut unnecessary data
3. Design better contracts
4. Stream large files

Ways to reduce message size

WCF messages can get big. Here's how to slim them down:

Better data contracts

Cut the fat:

• Use short names for data contracts
• Keep it flat, not nested
• Ditch unused fields

Instead of:

<PersonInformation>
  <FirstName>John</FirstName>
  <LastName>Doe</LastName>
  <Age>30</Age>
</PersonInformation>

Try:

<P>
  <F>John</F>
  <L>Doe</L>
  <A>30</A>
</P>

This can shrink your message by 30-50%.

Efficient serialization

Pick the right method:

• DataContract Serializer beats XMLSerializer
• JSON for lighter payloads
• Binary formats like MessagePack or Protocol Buffers

Using compression

GZIP can slash message size:

• IIS-hosted: Enable site compression
• Self-hosted: Use binary message encoder

Add compression:

1. Install Nuget package:

   PM> Install-Package Rashans.WCF.Compression
   

2. Set up GZIP for service and client

Binary encoding

Go binary, not text:

• Cuts size by about 50%
• Works well with optimized contracts

To use:

1. NetHttpBinding (binary by default)
2. Or custom binding with binary encoding

Smart message design

Break it down:

• Send data in smaller chunks
• Use paging for big result sets

XML optimization

Lean XML:

• No whitespace
• Short element names
• Skip attributes when possible

Streaming large data

For big files:

• Use streams, don't embed
• Avoid Base64 (adds 33% size)

Mix these techniques to shrink your WCF messages. GoCardless optimized 60% of their inter-service communication with about 30 data contracts.

Pro tip: Always measure before and after to track your gains.

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Advanced methods

When basic techniques don't cut it, try these advanced methods to shrink WCF messages:

Custom encoders

Build encoders that fit your data types like a glove. Here's how:

1. Extend MessageEncoder class
2. Implement ReadMessage and WriteMessage methods
3. Add your compression magic

Here's a bare-bones example:

public class CustomCompressedEncoder : MessageEncoder
{
    public override Message ReadMessage(Stream stream, int maxSizeOfHeaders, string contentType)
    {
        // Your decompression code here
    }

    public override void WriteMessage(Message message, Stream stream)
    {
        // Your compression code here
    }
}

Message inspectors

These let you tweak messages on the fly. Want to strip out fluff? You can do that.

To use one:

1. Implement IClientMessageInspector or IDispatchMessageInspector
2. Add your logic to the interface methods

Here's a simple header logger:

public class HeaderLoggerInspector : IDispatchMessageInspector
{
    public object AfterReceiveRequest(ref Message request, IClientChannel channel, InstanceContext instanceContext)
    {
        foreach (MessageHeader header in request.Headers)
        {
            Console.WriteLine($"Header: {header}");
        }
        return null;
    }

    public void BeforeSendReply(ref Message reply, object correlationState)
    {
        // Add your logic here
    }
}

Custom behaviors

These apply your optimizations automatically. Here's how to make one:

1. Implement IServiceBehavior
2. Override ApplyDispatchBehavior to add your tweaks

Check out this example:

public class CompressionBehavior : IServiceBehavior
{
    public void ApplyDispatchBehavior(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase)
    {
        foreach (ChannelDispatcher channelDispatcher in serviceHostBase.ChannelDispatchers)
        {
            foreach (EndpointDispatcher endpointDispatcher in channelDispatcher.Endpoints)
            {
                endpointDispatcher.DispatchRuntime.MessageInspectors.Add(new CompressionMessageInspector());
            }
        }
    }

    // Other interface methods go here
}

These advanced methods give you more control over message size. Mix and match them to find the perfect balance for your WCF app.

Tracking message sizes

Want to boost your WCF service performance? Keep an eye on those message sizes. Here's how:

Measurement tools

You need two things:

1. A message inspector
2. A way to calculate message sizes

Here's a quick code snippet:

private static long CalculateSize(Message message)
{
    using (var ms = new MemoryStream())
    {
        using (var writer = XmlDictionaryWriter.CreateBinaryWriter(ms))
        {
            message.WriteMessage(writer);
            return ms.Position;
        }
    }
}

This writes the message to a MemoryStream and gives you its size. Use it in your message inspector's BeforeSendReply method to log outgoing message sizes.

Performance counters

WCF has built-in tools to track message sizes over time:

1. Enable counters in app.config:

<configuration>
    <system.serviceModel>
        <diagnostics performanceCounters="All" />
    </system.serviceModel>
</configuration>

2. Use Performance Monitor (Perfmon.exe) to see the data

Look for ServiceModelService 4.0.0.0 counters. Instance names follow this pattern:

ServiceName@ServiceBaseAddress

Heads up: If instance names get too long, WCF will use a hash value for part of it. This sidesteps Windows' name length limits.

Pros and cons

WCF message size reduction is a balancing act. Here's the lowdown:

Size vs. readability

Smaller messages can boost performance, but at a cost:

• Faster travel, less latency
• Lower bandwidth use and costs
• Harder to debug (compressed/binary formats)
• Tougher to maintain optimized code

"Write code for your future self and for your team, not for the average user." - Davide Bellone

This quote nails it: balance optimization with maintainability.

Compatibility issues

Custom solutions can cause headaches:

• Integration problems with non-standard formats
• Potential breaks when updating WCF
• More complex testing needs

To tackle these:

1. Stick to built-in WCF features when you can
2. Document custom work thoroughly
3. Test, test, test across different scenarios

The goal? Find that sweet spot between efficiency and practicality.

Quick comparison:

Aspect	Small Messages	Readable Code
Performance	Faster	Can be slower
Debugging	Harder	Easier
Maintenance	More complex	Simpler
Compatibility	Potential issues	Generally better

Tips and common mistakes

Let's look at how to optimize WCF message sizes and avoid some common errors.

Optimization checklist

1. Choose the right serializer

DataContractSerializer is about 10% faster than XmlSerializer. It handles fields and private members, making it a good pick for most cases.

2. Pick the proper binding

Choose a binding that fits your needs:

Binding	Use Case
BasicHttpBinding	ASMX-style services
NetTcpBinding	Cross-machine communication

3. Enable tracing

Turn on tracing in your config. It's off by default but key for debugging and performance checks.

4. Adjust throttling settings

Default throttling might not work in production. Adjust based on your app's needs.

5. Use asynchronous calls

For long tasks, go async. It keeps things running smooth and doesn't block other clients.

Mistakes to avoid

1. Leaving proxies open

Close your proxy after use. Open proxies can cause resource leaks and slow things down.

2. Ignoring default settings

Don't assume defaults will work. Especially with throttling, you need to customize.

3. Overlooking binding options

In March 2022, Microsoft found switching from WSHttpBinding to BasicHttpBinding cut down on acknowledgements, speeding things up by 15%.

4. Skipping benchmarks

Set up performance checks before and after tuning. Without them, you're guessing.

5. Neglecting instrumentation

Instrument your app. It's crucial for tuning performance and finding bottlenecks.

Conclusion

WCF message size reduction is crucial for performance. Here's a quick recap:

1. Lean contracts: Cut unnecessary fields
2. DataContractSerializer: 10% faster than XmlSerializer
3. IIS compression: Enable for static and dynamic content
4. Binary encoding: Try MessagePack or Protocol Buffers
5. BasicHttpBinding: Use when WS features aren't needed

The future of WCF optimization might include AI-driven techniques, new serialization formats, and cloud-native adaptations.

But remember: there's no one-size-fits-all solution. Test and monitor your specific use case.

"If you've set your service to use PerCall or PerSession instance context mode and upped the throttling settings, but are still not getting the response times you're looking for, then it's worth investigating whether the calls are being queued because there is not enough IO threads in the ThreadPool to handle the requests." - Microsoft WCF Documentation

Keep optimizing WCF performance, but don't forget about security and maintainability.

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