YMA-MDL

<AML>
  <Item action="edit" type="ItemType" id="8B0779BD0C174C0A875E37F7D78B9B57">
    <Relationships>
      <Item action="add" type="Property">
        <data_type>foreign</data_type>
        <name>foreigntest2</name>
        <data_source >DF1F9AA824E045FCA06794B7CDEFB345</data_source>
        <foreign_property type="Property">B8CBB2ED30B041EDB4278C58CD73FD86</foreign_property>
      </Item>
    </Relationships>

YMA-MDL

// retrieve the document name
String documentName = this.getProperty("name");

// retrieve the document id
String documentID = this.getID();

// create the POST web request
var httpWebRequest = (HttpWebRequest) WebRequest.Create("https://hooks.slack.com/services/XXXXX/XXXXX/XXXXXXXXXX");
httpWebRequest.ContentType = "text/json";
httpWebRequest.Method = "POST";

YMA-MDL

var httpWebRequest = (HttpWebRequest) WebRequest.Create("https://hooks.slack.com/services/XXXXXXXXX/XXXXXXXXXXX/XXXXXXXXXXXXXXXXXXXXXXX");
httpWebRequest.ContentType = "text/json";
httpWebRequest.Method = "POST";

using(var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream())) {
    string json = "{\"text\":\"test message from Aras Innovator to Slack\"," +
        "\"username\":\"Innovator\"}";

    streamWriter.Write(json);
    streamWriter.Flush();