public override string AsGml(DbGeography geographyValue)
        {
            CheckParameterNotNull("geographyValue", geographyValue);

            dynamic providerValue = geographyValue.ProviderValue;
            return providerValue.AsGml().Value;
        }

        public override DbGeography Buffer(DbGeography geographyValue, double distance)
        {
            CheckParameterNotNull("geographyValue", geographyValue);

            dynamic providerValue = geographyValue.ProviderValue;
            return GeographyFromProviderValue(providerValue.STBuffer(distance));
        }

        public override string AsText(DbGeography geographyValue)
        {
            CheckParameterNotNull("geographyValue", geographyValue);

            dynamic providerValue = geographyValue.ProviderValue;
            return providerValue.STAsText().ToSqlString().Value;
        }

        public override byte[] AsBinary(DbGeography geographyValue)
        {
            CheckParameterNotNull("geographyValue", geographyValue);

            dynamic providerValue = geographyValue.ProviderValue;
            return providerValue.STAsBinary().Value;
        }

 private static ReadOnlySpatialValues CheckCompatible(DbGeography geographyValue)
 {
     Debug.Assert(geographyValue != null, "Validate geographyValue is non-null before calling CheckCompatible");
     if (geographyValue != null)
     {
         ReadOnlySpatialValues expectedValue = geographyValue.ProviderValue as ReadOnlySpatialValues;
         if (expectedValue != null)
         {
             return expectedValue;
         }
     }
     throw SpatialExceptions.GeographyValueNotCompatibleWithSpatialServices("geographyValue");
 }

 public override DbGeography PointAt(DbGeography geographyValue, int index)
 {
     throw SpatialServicesUnavailable();
 }

 public override bool? GetIsClosed(DbGeography geographyValue)
 {
     throw SpatialServicesUnavailable();
 }

 public override DbGeography SymmetricDifference(DbGeography geographyValue, DbGeography otherGeography)
 {
     throw SpatialServicesUnavailable();
 }

 public override double Distance(DbGeography geographyValue, DbGeography otherGeography)
 {
     throw SpatialServicesUnavailable();
 }

 public override bool Intersects(DbGeography geographyValue, DbGeography otherGeography)
 {
     throw SpatialServicesUnavailable();
 }

 /// <summary>
 /// Returns a nullable double value that indicates the area of the given <see cref="DbGeography"/> value, which may be null if the value does not represent a surface.
 /// <param name="geographyValue">The geography value, which need not represent a surface.</param>
 /// <returns>The area of <paramref name="geographyValue"/>, if it represents a surface; otherwise <c>null</c>.</returns>
 /// </summary>
 /// <exception cref="ArgumentNullException"><paramref name="geographyValue"/> is null.</exception>
 /// <exception cref="ArgumentException"><paramref name="geographyValue"/> is not compatible with this spatial services implementation.</exception>
 public abstract double? GetArea(DbGeography geographyValue);

 /// <summary>
 /// Returns a point element of the given <see cref="DbGeography"/> value, if it represents a linestring or linear ring.
 /// <param name="geographyValue">The geography value, which need not represent a linestring or linear ring.</param>
 /// <param name="index">The position within the geography value from which the element should be taken.</param>
 /// <returns>The point in <paramref name="geographyValue"/> at position <paramref name="index"/>, if it represents a linestring or linear ring; otherwise <c>null</c>.</returns>
 /// </summary>
 /// <exception cref="ArgumentNullException"><paramref name="geographyValue"/> is null.</exception>
 /// <exception cref="ArgumentException"><paramref name="geographyValue"/> is not compatible with this spatial services implementation.</exception>
 public abstract DbGeography PointAt(DbGeography geographyValue, int index);

 /// <summary>
 /// Returns the number of points in the given <see cref="DbGeography"/> value, if it represents a linestring or linear ring.
 /// <param name="geographyValue">The geography value, which need not represent a linestring or linear ring.</param>
 /// <returns>The number of elements in <paramref name="geographyValue"/>, if it represents a linestring or linear ring; otherwise <c>null</c>.</returns>
 /// </summary>
 /// <exception cref="ArgumentNullException"><paramref name="geographyValue"/> is null.</exception>
 /// <exception cref="ArgumentException"><paramref name="geographyValue"/> is not compatible with this spatial services implementation.</exception>
 public abstract int? GetPointCount(DbGeography geographyValue);

 /// <summary>
 /// Returns a nullable Boolean value that whether the given <see cref="DbGeography"/> value is closed, which may be null if the value does not represent a curve.
 /// <param name="geographyValue">The geography value, which need not represent a curve.</param>
 /// <returns><c>true</c> if <paramref name="geographyValue"/> represents a closed curve; <c>false</c> if <paramref name="geographyValue"/> represents a curve that is not closed; otherwise <c>null</c>.</returns>
 /// </summary>
 /// <exception cref="ArgumentNullException"><paramref name="geographyValue"/> is null.</exception>
 /// <exception cref="ArgumentException"><paramref name="geographyValue"/> is not compatible with this spatial services implementation.</exception>
 public abstract bool? GetIsClosed(DbGeography geographyValue);

 /// <summary>
 /// Returns a <see cref="DbGeography"/> value that represents the end point of the given DbGeography value, which may be null if the value does not represent a curve.
 /// <param name="geographyValue">The geography value, which need not represent a curve.</param>
 /// <returns>The end point of <paramref name="geographyValue"/>, if it represents a curve; otherwise <c>null</c>.</returns>
 /// </summary>
 /// <exception cref="ArgumentNullException"><paramref name="geographyValue"/> is null.</exception>
 /// <exception cref="ArgumentException"><paramref name="geographyValue"/> is not compatible with this spatial services implementation.</exception>
 public abstract DbGeography GetEndPoint(DbGeography geographyValue);

 public override string AsGml(DbGeography geographyValue)
 {
     geographyValue.CheckNull("geographyValue");
     ReadOnlySpatialValues expectedValue = CheckCompatible(geographyValue);
     return expectedValue.GML;
 }

 public override bool Disjoint(DbGeography geographyValue, DbGeography otherGeography)
 {
     throw SpatialServicesUnavailable();
 }

 /// <summary>
 /// Creates an instance of <see cref="DbGeographyWellKnownValue"/> that represents the specified <see cref="DbGeography"/> value using one or both of the standard well known spatial formats.
 /// </summary>
 /// <param name="geographyValue"></param>
 /// <returns>The well known representation of <paramref name="geographyValue"/>, as a new <see cref="DbGeographyWellKnownValue"/>.</returns>
 /// <exception cref="ArgumentNullException"><paramref name="geographyValue"/> is null.</exception>
 /// <exception cref="ArgumentException"><paramref name="geographyValue"/> is not compatible with this spatial services implementation.</exception>
 public abstract DbGeographyWellKnownValue CreateWellKnownValue(DbGeography geographyValue);

 public override DbGeography Buffer(DbGeography geographyValue, double distance)
 {
     throw SpatialServicesUnavailable();
 }

 public override DbGeographyWellKnownValue CreateWellKnownValue(DbGeography geographyValue)
 {
     geographyValue.CheckNull("geographyValue");
     ReadOnlySpatialValues backingValue = CheckCompatible(geographyValue);
     return new DbGeographyWellKnownValue() { CoordinateSystemId = backingValue.CoordinateSystemId, WellKnownBinary = backingValue.CloneBinary(), WellKnownText = backingValue.Text };
 }