<backends>
  <backend name="small">
    <class>B1</class>
    <options>
      <public>true</public>
    </options>
  </backend>

  <backend name="medium">
    <class>B2</class>
    <instances>3</instances>
    <options>
      <fail-fast>true</fail-fast>
    </options>
  </backend>

  <backend name="big">
    <class>B4</class>
    <options>
      <dynamic>true</dynamic>
    </options>
  </backend>
</backends>
