title: How Add custom properties in AppenderSkeleton log4net
body: <p>I Create Custom Appender(with AppenderSkeleton) that Connect to the Web Service... in this Appender i need to send some custom properties(like Url , Browser ,User , ...) to the web Service...
  but when i add this properties like :  </p>
  
  <pre><code>ThreadContext.Properties["addr"] = System.Web.HttpContext.Current.Request.UserHostAddress;
  </code></pre>
  
  <p>in my appender that like this :</p>
  
  <pre><code>public class UrlLogAppender : AppenderSkeleton
      {
  
          public string APIkey { get; set; }
          public string CustomerName { get; set; }
  
          protected override void Append(LoggingEvent loggingEvent)
          {
              try
              {
                  Base.LogToDataBase.WebService1 LogtoWebserver = new Base.LogToDataBase.WebService1();
  
  
  
                  string Result = LogtoWebserver.Log(CustomerName, APIkey, loggingEvent.TimeStamp.ToString(), loggingEvent.ThreadName.ToString(), loggingEvent.Level.ToString(), loggingEvent.LoggerName, loggingEvent.RenderedMessage, loggingEvent.ExceptionObject.InnerException.Message.ToString(), loggingEvent.Properties["addr"].ToString(), loggingEvent.Properties["browser"].ToString(), loggingEvent.Properties["url"].ToString());
                  if (Result != "UnSucced!!")
                  {
                      //Say Excellent.... !
                  }
                  else
                  {
                      //Say Opps....!!
  
                  }
              }
              catch (Exception ex)
              {
                  throw new ApplicationException("An error occured while invoking the Logging REST API", ex);
              }
          }
  
          public UrlLogAppender()
          {
              //
              // TODO: Add constructor logic here
              //
          }
      }
  }`
  </code></pre>
  
  <p>i can't catch the properties that i added and filled before(<code>**loggingEvent.Properties["browser"].ToString()**</code>?!?!?!!?)</p>
  
  <p>my Web.Config like this :</p>
  
  <pre><code>  &lt;appender name="UrlAppender" type="log4net.Extensions.UrlLogAppender"&gt;
        &lt;threshold value="ALL"/&gt;
        &lt;CallingApp value="Base" /&gt;
        &lt;datePattern value="_yyyy-MM-dd.lo'g'"/&gt;
        &lt;APIkey value="321" /&gt;
        &lt;CustomerName value="Kanon" /&gt;
  
        &lt;layout type="log4net.Layout.PatternLayout"&gt;
          &lt;param name="ConversionPattern" value="%date User:%identity IP:%X{addr} Browser: %X{browser} Url: %X{url} [%thread] %-5level %c:%m%n"/&gt;
        &lt;/layout&gt;
      &lt;/appender&gt;
  </code></pre>
  
  <p>please Help me ! </p>