Explore contents of a running container in Docker

This is a short tip how to explorer the contents of a running container in Docker.



Get Docker for windows from here: Docker for Windows First off, we can list our containers with the following command:

docker container ls
Note the CONTAINER ID value. Use this to explore the contents of the running container:

docker exec -it 231 bash

Note that in this example I just have to type the necessary part of the Guid of the CONTAINER ID to discern it from others and issue an exec command with the parameters -it (interactive and pseudo tty session) followed with bash. From now on, I can explore the container easily: ls -al The following image sums this up:

Another cool tip, how about installing a new nginx web server on port 81 on your Windows Dev Box? Simple!

docker run --detach publish 81:80 nginx

And the following command pulls a windowsservercore docker image (10,7 GB size) and starts it up and gives you a pseudo-terminal which is interactive:

docker run -it microsoft/windowsservercore

Doubly Linked List in C#

I am reading the book "C#7 and .NET Core 2.0 High Performance" about data structures and came accross Doubly linked lists. This is an interesting data structure. We most often use arrays and lists in .NET in everyday use, but both are not as high performant as linked lists when it comes to inserting and removing items in their structure. Removing an item and inserting an item in a list is only quick, if we add to the end of the list or remove from the end of the list. Arrays have the same behavior, if you have a large data structure with many items, consider using a LinkedList instead. .NET already got a good implementation of linked lists in System.Collections.Generic with the LinkedListNode class, so this article just presents a class I wrote for fun on my own. If you want to see the source code of the .Net class, it is available here:
LinkedListNode implementation(Reference Source /.NET)
Now how fun is it to just use .NET's implementation, we want to learn something and do things ourselves as devoted coders? Therefore I present my own implementation! You can find the source code by cloning the following Git repo: Actually, the implementation is easy, the most cumbersome part is to be careful with the next and previous pointers. Just like the .NET implementation, this class supports generic and a payload of different types, in the demo I will use string as the payload of each node.

git clone https://toreaurstad@bitbucket.org/toreaurstad/doublylinkedlist.git

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
// ReSharper disable ArrangeThisQualifier
// ReSharper disable RedundantNameQualifier

namespace DoublyLinkedList
{

    /// <summary>
    /// Node in a doubly linked list data structure with pointers to the previous and next item in the linked list, if any.
    /// Allows quick insertion and removal of values in even large data structures
    /// </summary>
    /// <typeparam name="T">The type of Data in each node of the doubly linked list</typeparam>
    public class LinkedListNode<T>
    {

        public LinkedListNode(T data)
        {
            _data = data;
            _prev = null; //Init previous reference to null
            _next = null; //Init next reference to null
        }


        public T Data
        {
            get { return _data; }
        }

        /// <summary>
        /// Attempts to find a value in the doubly linked list. Uses object.Equals for comparison. O(N) complexity.
        /// </summary>
        /// <param name="value">Value to find</param>
        /// <returns>The first node with the matching value, if any.</returns>
        public LinkedListNode<T> Find(T value)
        {
            if (object.Equals(Data, value))
                return this;
            if (this._next is null)
                return null;
            return Find(this._next, value);
        }

        /// <summary>
        /// Attempts to find a value in the doubly linked list by a matchen with a given predicate. Returns null if no node values matches. O(N) complexity 
        /// </summary>
        /// <param name="searchCondition"></param>
        /// <returns></returns>
        public LinkedListNode<T> Find(Predicate<LinkedListNode<T>> searchCondition)
        {
            if (searchCondition(this))
                return this;
            if (this._next != null)
                return this._next.Find(searchCondition);
            return null;
        }

        /// <summary>
        /// Searches for multiple values and returns the nodes found. The search returns the first match if any for every search value. O(N*N) complexity.
        /// </summary>
        /// <param name="values"></param>
        /// <returns></returns>
        public LinkedListNode<T>[] FindMultiple(params T[] values)
        {
            if (values is null)
                throw new ArgumentNullException(nameof(values));
            if (!values.Any())
                throw new ArgumentException("Please provide a nonempty array of values!");
            var foundValues = new List<LinkedListNode<T>>();
            foreach (T value in values)
            {
                LinkedListNode<T> foundValue = Find(value);
                if (foundValue != null)
                    foundValues.Add(foundValue);
            }

            return foundValues.ToArray();
        }

        // ReSharper disable once UnusedMember.Local
        private LinkedListNode<T> Find(LinkedListNode<T> node, Predicate<T> searchCondition)
        {
            if (node is null)
                return null;
            if (searchCondition(node.Data))
                return node;
            if (node._next != null)
                return Find(node._next, searchCondition);
            return null;
        }

        private LinkedListNode<T> Find(LinkedListNode<T> node, T value)
        {
            if (node is null)
                return null;
            if (object.Equals(node.Data, value))
                return node;
            if (node._next != null)
                return Find(node._next, value);
            return null;
        }

        /// <summary>
        /// Inserts a node into the doubly linked list. Adjusts the prev and next pointers of the inserted node. O(1) complexity.
        /// </summary>
        /// <param name="node">The node to insert, node's prev and next pointers will be overwritted if already set.</param>
        /// <returns>The inserted node with updated prev and next pointers</returns>
        public LinkedListNode<T> Insert(LinkedListNode<T> node)
        {
            if (node is null)
                throw new ArgumentNullException(nameof(node));

            LinkedListNode<T> nextNode = this._next;
            node._prev = this;
            this._next = node;
            node._next = nextNode;
            if (nextNode != null)
                nextNode._prev = node;

            return node;
        }

        /// <summary>
        /// Inserts multiple nodes into the doubly linked list by building nodes with passed in values. O(1) complexity.
        /// </summary>
        /// <param name="values"></param>
        /// <returns></returns>
        public LinkedListNode<T>[] Insert(params T[] values)
        {
            if (values is null)
                throw new ArgumentNullException(nameof(values));
            if (!values.Any())
                throw new ArgumentException("Please provide a nonempty array of values!");

            values = values.Reverse().ToArray(); //Reverse order so insertion behaves sequentially 

            var inserted = new List<LinkedListNode<T>>();

            foreach (T value in values)
            {
                LinkedListNode<T> node = new LinkedListNode<T>(value);
                inserted.Add(Insert(node));
            }

            return inserted.ToArray();
        }

        /// <summary>
        /// Removes a node from the linked list. Adjusts the previous and next pointers of removed node. O(1) complexity.
        /// </summary>
        /// <param name="node"></param>
        /// <returns></returns>
        public LinkedListNode<T> Remove(LinkedListNode<T> node)
        {
            if (node is null)
                throw new ArgumentNullException(nameof(node)); 

            if (node._prev != null)
                node._prev._next = node._next;
            if (node._next != null)
                node._next._prev = node._prev;

            //Set unneeded references to null now and to avoid misuse
            node._prev = null;
            node._next = null;

            return node;
        }

        public void Remove()
        {
            if (this._prev != null)
                this._prev._next = this._next;
            if (this._next != null)
                this._next._prev = this._prev;

            //Set unneeded references to null now and to avoid misuse
            this._prev = null;
            this._next = null;
        }

        public override string ToString()
        {
            StringBuilder sb = new StringBuilder();
            if (this._prev is null)
                sb.Append(Head);
            sb.Append(_data + GetArrow(this));
            IterateLinkedList(this._next, sb);
            return sb.ToString();
        }

        /// <summary>
        /// Iterates the doubly linked list and builds a string to output in the ToString() method
        /// </summary>
        /// <param name="node">LinkedListNode</param>
        /// <param name="sb">StringBuilder</param>
        private void IterateLinkedList(LinkedListNode<T> node, StringBuilder sb)
        {
            if (node != null)
            {
                sb.Append(node.Data + GetArrow(node));
                if (node._next != null)
                    IterateLinkedList(node._next, sb);
            }
        }

        private string GetArrow(LinkedListNode<T> node)
        {
            if (node != null)
            {
                if (node._next != null && node._next._prev != null)
                    return DoubleArrow;
                if (node._next != null && node._next._prev == null)
                    return Arrow;
                if (node._next == null)
                    return Arrow + NullString;
            }

            return ArrowUndefined;
        }

        private const string Head = "HEAD->";

        private const string Arrow = "->";

        private const string DoubleArrow = "<->";

        private const string ArrowUndefined = "??MISSINGLINK??";

        private const string NullString = "NULL";

        private readonly T _data;

        private LinkedListNode<T> _prev;

        private LinkedListNode<T> _next;

    }
}

This implementation has not got a specific pointer to the head of the list like a circular linked list can provide. The following code makes use of this class to demonstrate its usage:

using System;
using System.Diagnostics;
using System.Linq;

namespace DoublyLinkedList
{
    class Program
    {
        // ReSharper disable once UnusedParameter.Local
        static void Main(string[] args)
        {
            var root = new LinkedListNode("Hello");
            root.Insert(new LinkedListNode("world"));
            root.Insert(new LinkedListNode("Testing"));
            root.Insert(new LinkedListNode("Double linked list!"));

            root.Insert("Inserting", "some", "values!");

            root.Insert("Delete", "me", "please");

            root.FindMultiple("Delete", "me").ToList().ForEach(n => n.Remove(n));

            root.Find(n => n.Data.Contains("pl")).Remove();

            var mismatch = root.Find("Nonexisting value");
            Debug.Assert(mismatch is null, "Expected to not find any item in this doubly linked list with this search value");

            string rootRepresentation = root.ToString();

            Debug.Assert(rootRepresentation == @"HEAD->Hello<->Inserting<->some<->values!<->Double linked list!<->Testing<->world->NULL");

            Console.WriteLine(rootRepresentation);

            Console.ReadKey();
        }
    }
}

The output of this linked list is displaying the contents of the doubly linked list:

HEAD->Hello<->Inserting<->some<->values!<->Double linked list!<->Testing<->world->NULL

As we can see, with our ToString implementation we can deduce that the first and last node is special, the first one lacks a prev pointer illustrated by "HEAD->" and the last node lacks a next pointer illustrated with "->NULL". You will find this in the implementation of the class. I have decided to actually revert the order if the client wants to insert multiple values, as that ordering behaves more naturally. The client can look after a value or multiple values or search with a given predicate, or pass in a node and use it to search. Also, it is possible to remove a node. We end up with an implementation of a Doubly Linked list that can be used in many scenarios. I would advice you to use the .NET version as it supports more features, such as a pointer to the HEAD node. But this implementation is compact and easy to understand for many developers. You will usually use linked list in scenarios where you have much data and want to quickly insert or remove one or several nodes in the linked list. It also supports quick navigation from a node to its previous or next node. Imagine for example working with a class called Book which needs to have an iterable structure ("Pages") to move to the next and previous page and at the same time insert new pages or removing a page from the middle of the data structure. Using an array or a list would be low performant and slow, while a doubly linked list would actually allow the developer to create code that quickly inserts a new page or removes a page at an arbitrary position in the data structure of the Book. This class can of course be optimized to support for example circular linked list with a pointer always to HEAD, or maybe you want to have pointer to HEAD and TAIL and not have a circular list? The source code should be relatively self explanatory for the intermediate C#-developer to revise and improve. I hope you found this article interesting.

Swapping variables in C# Unmanaged / Managed

This article will shortly present two ways of swapping variables in C#. Specifically, these two ways are only both available for value types and structs and unmanaged types, while the managed swap by using ref is available for values, structs and managed structs. The method UnsafeSwap swaps two variables by using unsafe code and pointers. By passing in the address of the two variables to swap, it is possible to use the dereference operator * to not only copy into a temporary variable but also use the syntax *a = *b to exchange the address the variable is pointing to, effectively we swap to variables with their content, here int is used. Another way is do a SafeSwap where we pass in the ref of the variables and just change their contents. Note that if you want to exchange two strings, you must pin the pointer of the chars using the fixed keyword.

unsafe void Main()
{
 int one = 20;
 int two = 30;

 Console.WriteLine("Before swap, one: {0}, two: {1}", one, two);

 UnsafeSwap(&one, &two);
 
 Console.WriteLine("Unsafe swap, one: {0}, two: {1}", one, two); 
 
 SafeSwap(ref one, ref two);

 Console.WriteLine("Safe swap back again, one: {0}, two: {1}", one, two);

}

unsafe void UnsafeSwap(int* a, int* b){
 int temp = *a;
 *a = *b;
 *b = temp; 
}

void SafeSwap(ref int a, ref int b){
 int temp = a;
 a = b;
 b = temp;
}

To exchange two string variables, we must use the fixed keyword and of course only be able to exchange the characters from the char array consisting the first variable to be exchanged with the char array of the second variable. In addition, the string in C# is at a low level actually a character array null terminated with the '\0' sequence, at least when a string is treated as a character array.. The following method will exchange two string variables using unsafe / unmanaged code. Note that the two strings differ in length, so the last character is not exchanged. That is - our string is actually a character array and consists of multiple memory addresses.

unsafe void Main()
{
 fixed (char* one = "hello??")
 {
  fixed (char* two = "world!")
  {
   char* ptrone = one;
   char* ptrtwo = two;

   while (*ptrone != '\0' && *ptrtwo != '\0')
   {
    Swap(ptrone, ptrtwo);
    Console.WriteLine("one: {0}", GetString(one));
    Console.WriteLine("two: {0}", GetString(two));
    ++ptrone;
    ++ptrtwo;
   }

  }
 }
 
}

unsafe void Swap(char* first, char* second){
 char temp = *first;
 *first = *second;
 *second = temp;
}

unsafe string GetString(char* input){
 char* ptr = input; 
 var sw = new StringBuilder();
 while (*ptr != '\0')
 {
  sw.Append(ptr->ToString());
  ++ptr;
 }
 return sw.ToString();
}

The output in Linqpad gives as the exchange of the string or actually a null terminated character array progresses:

one: wello?? two: horld! one: wollo?? two: herld! one: worlo?? two: helld! one: worlo?? two: helld! one: world?? two: hello! one: world!? two: hello?

Simple Base64 encoder in C#

Just read a bit about Base64 encoding and decided to try out writing my own in Linqpad for strings! The way you Base64 encode is to treat each char in the input string as a byte value with groups of six bytes (this byte value is zero padded left) and then mapping the 2^6 values into a Base64 table and outputting the corresponding values into a resulting string. Note that you also pad the Base64 string with '=' char to ensure the entire bit length is divisible with three. That is why Base64 strings in .NET always have 0,1 or 2 '=' chars at the end. The characters used in the Base64 encoding is in .NET the chars [A-z] and [0-9] plus + and slash /.

void Main()
{
 string wordToBase64Encode = "Hello world from base64 encoder. This is a sample input string, does it work?"; 
 string wordBase64EncodedAccordingToNet = Convert.ToBase64String(Encoding.ASCII.GetBytes(wordToBase64Encode)).Dump();
 string wordBase64EncodedAccordingToCustomBase64 = wordToBase64Encode.ToBase64String().Dump();
 (("Are the two strings equal?: ") + string.Equals(wordBase64EncodedAccordingToNet, wordBase64EncodedAccordingToCustomBase64)).Dump();
 
}

public static class LowLevelBase64Extensions {

    private static readonly char[] _base64Table =
 {
  'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 
  'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
  'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 
  'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
  '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/',
 };

 public static string ToBase64String(this string toBeEncoded){
     byte[] toBeEncodedByteArray = Encoding.ASCII.GetBytes(toBeEncoded);
  string toBeEncodedBinaryString = 
  string.Join("", 
   toBeEncodedByteArray.Select(b => (Convert.ToString(b, 2).PadLeft(8, '0'))));
   
  //toBeEncodedBinaryString.Length.Dump();
   
  int padCharacters = toBeEncodedBinaryString.Length % 3;
  //toBeEncoded.Dump();
       
  StringWriter sw = new StringWriter();

  for (var i = 0; i < toBeEncodedBinaryString.Length; i = i + 6)
  {
   string encodingToMap =
    toBeEncodedBinaryString.Substring(i, Math.Min(toBeEncodedBinaryString.Length - i, 6))
    .PadRight(6, '0');
   //encodingToMap.Dump();
   byte encodingToMapByte = Convert.ToByte(encodingToMap, 2);
   char encodingMapped = _base64Table[(int)encodingToMapByte];
   sw.Write(encodingMapped);
  }
  
  sw.Write(new String('=', padCharacters));
  
  //Check 24 bits / 3 byte padding 
  return sw.ToString();
 }
}

Note - the casting to int of the encodingToMapByte also works if you cast the byte representation to short or byte. I have compared this custom Base64Encoder with .NET's own Convert.ToBase64String(), and they give equal strings in the use cases I have tried out. Make note that this is just playing around, .NET's own method is optimized for speed. This is more to show what happens with the input string to generate a Base64 encoded string. You can use this code as a basis for custom encoding shemes like Base32. I have used Encoding.ASCII.GetBytes to look up the ASCII code. So this implementation primarily supports input strings in languages using ASCII and Extended ASCII characters, at least that is what I have tested it with. The output in Linqpad shows the following corresponding results:

Consuming video from WCF as a Base64 encoded strings

This article follows up our quest of loading up video byte arrays from WCF efficiently, but now the byte array is converted into a Base64 encoded string. You can start by cloning the repository I have prepared from here:
git clone https://toreaurstad@bitbucket.org/toreaurstad/wcfaudiostreamdemo.git git fetch && git checkout VideBase64String_05082018
Base64 encoded strings take six bits from the byte array and designates is as a char where the char can be one of 64 characters, in MIME implementation it is [A-z][0-9] and + and /, which is 64 different characters that the six bytes are encoded into. This means that 24 bits can be represented as three Base64 encodeded characters, that is 3 bytes in our byte array can be represented as FOUR base64 encoded chars. This 3:4 ratio is the rationale behind the MTOM optimization in WCF (to be discussed later). However, recap from the previous article where we downloaded a video sizing 4 MB on disk and Fiddler reporting it to be about 3 times larger. This is bloated data that I want to explore if we can fix up a bit. The bloated data is because I have managed not to truly enforce the XMLHttpRequest to send the data through the WCF REST binding (webHttpBinding) as true binary data - binary data is still sent as a string object to Javascript. This is sad, and I want to try to speed this up and avoid bloated data. To get this size down, we can start by using a Base64 encoded string instead in our XmlHttpRequest. First off, we define a service contract operation to return our string with Base64 data:

        [OperationContract]
        [WebGet(UriTemplate = "mediabytes/{videofile}")]
        string GetVideoAsBase64(string videofile);

Now our Service Implementation looks like this:

using System;
using System.IO;
using System.ServiceModel.Activation;
using System.ServiceModel.Web;
using System.Web;
using WcfStreamAudioDemo.Common;

namespace WcfStreamAudioDemo.Host
{

    [AspNetCompatibilityRequirements (RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
    public class VideoService : IVideoServiceContract
    {

        public Stream GetVideo(string videofile)
        {
            return GetVideoStream(videofile, ".mp4");
        }

        public string GetVideoAsBase64(string videofile)
        {
            Stream videoStream = GetVideoStream(videofile, ".mp4");

            byte[] buffer = new byte[32*1024];
            int count;
            var memoryStream = new MemoryStream();

            while ((count = videoStream.Read(buffer, 0, buffer.Length)) > 0)
            {
                memoryStream.Write(buffer, 0, count);
            }

            return Convert.ToBase64String(memoryStream.ToArray()); 
        }

        private Stream GetVideoStream(string videofile, string extension)
        {
            string mediaFolder = HttpContext.Current.Server.MapPath("~/media");
            string videoFileFullPath = Path.Combine(mediaFolder, videofile) + extension;
            return File.OpenRead(videoFileFullPath);
        }

    }
}

The client side code will now retrieve a Base64Encoded string. The following client side scripts loads up our video:

 <script type="text/javascript">

        window.onload = init;
      
        var source; //Video buffer 

        function init() {
            loadByteArray('http://myserver/WcfStreamAudioDemo.Host/VideoService.svc/mediabytes/sintel_trailer-480p');
        }

        function base64ToArrayBuffer(base64) {
            var binaryString =  window.atob(base64);
            var len = binaryString.length;
            var bytes = new Uint8Array( len );
            for (var i = 0; i < len; i++)        {
                bytes[i] = binaryString.charCodeAt(i);
            }
            return bytes.buffer;
        }

        function loadByteArray(url) {
            
            var request = new XMLHttpRequest();

            //request.overrideMimeType('text\/plain; charset=x-user-defined');
            //request.responseType = 'blob';

            request.open('GET', url, true);
            //request.setRequestHeader("Content-Type", "video/mp4");


            request.onload = function() {
                //console.log(request.response);
                debugger;

                var responseData = request.response;
                if (responseData === undefined || responseData === null)
                    return;

                responseData = responseData.slice(0, -9);
                responseData = responseData.substring(68);

                var videoByteArrayView = base64ToArrayBuffer(responseData);
            
                var blob = new Blob([videoByteArrayView], { type: "text/plain;charset=utf-8" });

                var blobUrl = URL.createObjectURL(blob);

                var videoCtrlFedByByteArray = document.getElementById("videoCtrlFedByByteArray");

                videoCtrlFedByByteArray.setAttribute("src", blobUrl);


            } //request.onload 

            request.send();

        }

    </script>

There is still a lot of manual Js scripting here to prepare the video here, I will try to explain. We have now managed to drastically reduce the bloated data of our original 4.4 MB video down from 15+ MB to just 5.8 MB using Base64 encoded string. The retrieved Base64 encoded string is first decoded with the Js atob() function ("ASCII to BINARY"). A Uint8Array is initialized with the length of this decoded binary string and the binary string is iterated by using the charCodeAt method, returning the ArrayBuffer inside the constructed Uint8Array. Note that I got the Base64 encoded string as a XML first, which is why I do some chopping off the string using slice and substring. Anyways, after getting an ArrayBuffer from the Uint8Array's buffer property, we can construct a Blob object (Binary large object) and create an object url and then set the "src" attribute of our HTML5 Video control to this blobUrl. This is still not very elegant, I have seen examples using "arraybuffer" as responseType of the XmlHttpRequest object in Js to retrieve binary data, but I got garbled data back trying to use it with WCF REST. So in this article you have seen a way to send binary data from a WCF method by using a Base64 encoded string as an intermediary between the Server and the client. We got the file size of the request according to Fiddler inspection down to much less than the bloated binary array transfer that actually sent the byte array as a text string back to the client.

Wcf byte array + HTML 5 Video + Custombinding

Again, this article looks at different ways to load byte array from WCF representing video data to web clients, this approach will return a byte array and use a CustomBinding in WCF. You can start by cloning the repository I have prepared from here:
git clone https://toreaurstad@bitbucket.org/toreaurstad/wcfaudiostreamdemo.git git fetch && git checkout VideBase64String_05082018
The following method is added to our WCF service contract, note that now we leave the webHttpBinding and use a CustomBinding.

     [OperationContract]
     byte[] GetVideoBytes(string videofile);

There is no [WebGet] attribute this time, as noted we will not use WCF REST but SOAP instead. The web.config of the host website for the WCF services exposes this CustomBinding:

<system.serviceModel>

    <services>
      
      <service name="WcfStreamAudioDemo.Host.AudioService">
        <endpoint behaviorConfiguration="RestBehaviorConfig" binding="webHttpBinding" bindingConfiguration="HttpStreaming" contract="WcfStreamAudioDemo.Common.IAudioServiceContract" />
      </service>
      
      <service name="WcfStreamAudioDemo.Host.VideoService">
        <endpoint behaviorConfiguration="RestBehaviorConfig" binding="webHttpBinding" bindingConfiguration="HttpStreaming" contract="WcfStreamAudioDemo.Common.IVideoServiceContract" />
        <endpoint address="custom" binding="customBinding" bindingConfiguration="CustomBinding" contract="WcfStreamAudioDemo.Common.IVideoServiceContract" />
      </service> 

    </services>
    

    <bindings>
      
     <customBinding>
        <binding name="CustomBinding">
          <binaryMessageEncoding>
            <readerQuotas maxArrayLength="100000000" maxStringContentLength="100000000"/>
          </binaryMessageEncoding>
          <httpTransport />
        </binding>
      </customBinding>

      <webHttpBinding>
        <binding name="HttpStreaming" transferMode="Streamed" maxReceivedMessageSize="1000000000" maxBufferPoolSize="100000000">
          <readerQuotas maxArrayLength="100000000" maxStringContentLength="100000000"/>
        </binding>
      </webHttpBinding>
    </bindings>
    
    <behaviors>

      <serviceBehaviors>
        <behavior>
          <!-- To avoid disclosing metadata information, set the values below to false before deployment -->
          <serviceMetadata httpGetEnabled="true" httpsGetEnabled="true"/>
          <!-- To receive exception details in faults for debugging purposes, set the value below to true.  Set to false before deployment to avoid disclosing exception information -->
          <serviceDebug includeExceptionDetailInFaults="true"/>
        </behavior>
      </serviceBehaviors>
     
      <endpointBehaviors>
        <behavior name="RestBehaviorConfig">
          <webHttp />
        </behavior>
      </endpointBehaviors>

    </behaviors>
    <protocolMapping>
        <add binding="basicHttpsBinding" scheme="https" />
    </protocolMapping>    
    <serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true" />
  </system.serviceModel>

Note that the custom binding allows us to set up a binaryMessageEncoding. The next step is to go to the client project and add a service reference to the host project containing the WCF service. The app.config file is then updated, relevant parts shown here:

 <system.webServer>
    <directoryBrowse enabled="true" />
    <security>
      <requestFiltering>
        <requestLimits maxAllowedContentLength="1073741824" />
      </requestFiltering>
    </security>
        <staticContent>
            <mimeMap fileExtension=".mp4" mimeType="video/mp4" />
        </staticContent>
  </system.webServer>


  <system.serviceModel>
    <bindings>
      
      <customBinding>
        <binding name="CustomBinding">
          <binaryMessageEncoding>
            <readerQuotas maxArrayLength="100000000" maxStringContentLength="100000000" />
          </binaryMessageEncoding>
          <httpTransport maxReceivedMessageSize="100000000" />
        </binding>
      </customBinding>

    </bindings>
    <client>
      <endpoint address="http://he139920.helsemn.no/WcfStreamAudioDemo.Host/VideoService.svc/custom" contract="VideoService.IVideoServiceContract" binding="customBinding" bindingConfiguration="CustomBinding" />
    </client>
    
  </system.serviceModel>

Note the changes of setting up a MIME map for .mp4 files and setting up requestlimits. I will explain this soon. The client script now actually consists both of a server side script run in ASP.NET that sets up the video control in two ways. One way is to construct a HTML5 Data Url. This clearly was demanding for the browser to cope with and is not recommended. The video is actually embed on the page as a base64 encoded string! For a small video such as our video, it is actually possible still. It is of course fascinating that we can embed an entire video on our ASPX web page just as a Base64 encoded string, like it or not. The way to do this anyways is like this:

<script runat="server">

    private void btnInvokeWcfService_OnClick(object sender, EventArgs e)
    {

        using (var proxy = new VideoServiceContractClient())
        {
            byte[] payload = proxy.GetVideoBytes("sintel_trailer-480p");

            SetVideoSourceToHtmlDataUri(payload);

        }
    }


    private void SetVideoSourceToHtmlDataUri(byte[] payload)
    {
        //Set a base64 Html data uri

        videoCtrlFedByByteArrayThroughProxy.Attributes["type"] = "video/mp4";

        string base64String = Convert.ToBase64String(payload);

        videoCtrlFedByByteArrayThroughProxy.Attributes["src"] = "data:video/mp4;base64," + base64String;
    }

</script>

The following image shows how this actually works! Of course, this gives rendering and performance issues, as the web page now got very large content - the entire video is embedded into the page! Another way is to write the byte array to a temporary file on the server, and set the src attribute to this temporary file.

<script runat="server">

    private void btnInvokeWcfService_OnClick(object sender, EventArgs e)
    {

        using (var proxy = new VideoServiceContractClient())
        {
            byte[] payload = proxy.GetVideoBytes("sintel_trailer-480p");

            SetVideoSourceToTempFile(payload);

        }
    }

    private void SetVideoSourceToTempFile(byte[] payload)
    {
        //write to a temp file 
        string tempfile = Path.GetRandomFileName() + ".mp4";
        string tempfilePathForWebServer = HttpContext.Current.Server.MapPath("media/") + tempfile;
        File.WriteAllBytes(tempfilePathForWebServer, payload);

        videoCtrlFedByByteArrayThroughProxy.Attributes["src"] = "media/" + tempfile;
    }

</script>

Note that in these two samples, I have adjusted the HTML5 video control to be accessible to ASP.NET like this:

   <asp:Button runat="server" ID="btnInvokeWcfService" Text="Load Video" OnClick="btnInvokeWcfService_OnClick"/>
        
        <video id="videoCtrlFedByByteArrayThroughProxy" type="video/mp4"  runat="server"  controls width="320" height="240">         
            <p>Your browser doesn't support HTML5 video. Here is a <a href="http://wcfaudiodemohost.azurewebsites.net/VideoService.svc/mediabytes/sintel_trailer-480p">link to the video</a> instead.</p> 
        </video>

This method of retrieving video from WCF is the quickest way, it only fetches the original byte array data and it loads quickly. An adjusted version would not write to a file directly accessible on the web server, but use for example IsolatedStorage instead. I will look into that in the future. Hope you found this article interesting. CustomBindings in WCF gives you a lot of flexibility!