/// <summary>
/// Pushes a new element onto the stack.
/// </summary>
/// <param name="op">The filter operator.</param>
/// <param name="operands">The operands.</param>
/// <returns></returns>
public ContentFilterElement Push(FilterOperator op, params object[] operands)
{
// check if nothing more to do.
if (operands == null || operands.Length == 0)
{
throw ServiceResultException.Create(StatusCodes.BadInvalidArgument, "ContentFilterElement does not have an operands.");
}
// create the element and set the operator.
ContentFilterElement element = new ContentFilterElement();
element.FilterOperator = op;
for (int ii = 0; ii < operands.Length; ii++)
{
// check if a FilterOperand was provided.
FilterOperand filterOperand = operands[ii] as FilterOperand;
if (filterOperand != null)
{
element.FilterOperands.Add(new ExtensionObject(filterOperand));
continue;
}
// check for reference to another ContentFilterElement.
ContentFilterElement existingElement = operands[ii] as ContentFilterElement;
if (existingElement != null)
{
int index = FindElementIndex(existingElement);
if (index == -1)
{
throw ServiceResultException.Create(StatusCodes.BadInvalidArgument, "ContentFilterElement is not part of the ContentFilter.");
}
ElementOperand operand = new ElementOperand();
operand.Index = (uint)index;
element.FilterOperands.Add(new ExtensionObject(operand));
continue;
}
// assume a literal operand.
LiteralOperand literalOperand = new LiteralOperand();
literalOperand.Value = new Variant(operands[ii]);
element.FilterOperands.Add(new ExtensionObject(literalOperand));
}
// insert the new element at the begining of the list.
m_elements.Insert(0, element);
// re-number ElementOperands since all element were shifted up.
for (int ii = 0; ii < m_elements.Count; ii++)
{
foreach (ExtensionObject extension in m_elements[ii].FilterOperands)
{
if (extension != null)
{
ElementOperand operand = extension.Body as ElementOperand;
if (operand != null)
{
operand.Index++;
}
}
}
}
// return new element.
return element;
}
/// <summary>
/// Constructs the event filter for the subscription.
/// </summary>
/// <returns>The event filter.</returns>
public EventFilter ConstructFilter(Session session)
{
EventFilter filter = new EventFilter();
// the select clauses specify the values returned with each event notification.
filter.SelectClauses = SelectClauses;
// the where clause restricts the events returned by the server.
// it works a lot like the WHERE clause in a SQL statement and supports
// arbitrary expession trees where the operands are literals or event fields.
ContentFilter whereClause = new ContentFilter();
// the code below constructs a filter that looks like this:
// (Severity >= X OR LastSeverity >= X) AND (SuppressedOrShelved == False) AND (OfType(A) OR OfType(B))
// add the severity.
ContentFilterElement element1 = null;
ContentFilterElement element2 = null;
if (Severity > EventSeverity.Min)
{
// select the Severity property of the event.
SimpleAttributeOperand operand1 = new SimpleAttributeOperand();
operand1.TypeDefinitionId = ObjectTypeIds.BaseEventType;
operand1.BrowsePath.Add(BrowseNames.Severity);
operand1.AttributeId = Attributes.Value;
// specify the value to compare the Severity property with.
LiteralOperand operand2 = new LiteralOperand();
operand2.Value = new Variant((ushort)Severity);
// specify that the Severity property must be GreaterThanOrEqual the value specified.
element1 = whereClause.Push(FilterOperator.GreaterThanOrEqual, operand1, operand2);
}
// add the suppressed or shelved.
if (!IgnoreSuppressedOrShelved)
{
// select the SuppressedOrShelved property of the event.
SimpleAttributeOperand operand1 = new SimpleAttributeOperand();
operand1.TypeDefinitionId = ObjectTypeIds.BaseEventType;
operand1.BrowsePath.Add(BrowseNames.SuppressedOrShelved);
operand1.AttributeId = Attributes.Value;
// specify the value to compare the Severity property with.
LiteralOperand operand2 = new LiteralOperand();
operand2.Value = new Variant(false);
// specify that the Severity property must Equal the value specified.
element2 = whereClause.Push(FilterOperator.Equals, operand1, operand2);
// chain multiple elements together with an AND clause.
if (element1 != null)
{
element1 = whereClause.Push(FilterOperator.And, element1, element2);
}
else
{
element1 = element2;
}
}
// add the event types.
if (EventTypes != null && EventTypes.Count > 0)
{
element2 = null;
// save the last element.
for (int ii = 0; ii < EventTypes.Count; ii++)
{
// for this example uses the 'OfType' operator to limit events to thoses with specified event type.
LiteralOperand operand1 = new LiteralOperand();
operand1.Value = new Variant(EventTypes[ii]);
ContentFilterElement element3 = whereClause.Push(FilterOperator.OfType, operand1);
// need to chain multiple types together with an OR clause.
if (element2 != null)
{
element2 = whereClause.Push(FilterOperator.Or, element2, element3);
}
else
{
element2 = element3;
}
}
// need to link the set of event types with the previous filters.
if (element1 != null)
{
whereClause.Push(FilterOperator.And, element1, element2);
}
}
filter.WhereClause = whereClause;
// return filter.
return filter;
}
/// <summary>
/// Converts an ContentFilterElement to a displayable string.
/// </summary>
/// <param name="nodeTable">The node table.</param>
/// <returns>ContentFilterElement as a displayable string.</returns>
public virtual string ToString(INodeTable nodeTable)
{
List <FilterOperand> operands = GetOperands();
string operand1 = (operands.Count > 0)?operands[0].ToString(nodeTable):null;
string operand2 = (operands.Count > 1)?operands[1].ToString(nodeTable):null;
string operand3 = (operands.Count > 2)?operands[2].ToString(nodeTable):null;
StringBuilder buffer = new StringBuilder();
switch (FilterOperator)
{
case FilterOperator.OfType:
case FilterOperator.InView:
case FilterOperator.IsNull:
case FilterOperator.Not:
{
buffer.AppendFormat("{0} '{1}'", FilterOperator, operand1);
break;
}
case FilterOperator.And:
case FilterOperator.Equals:
case FilterOperator.GreaterThan:
case FilterOperator.GreaterThanOrEqual:
case FilterOperator.LessThan:
case FilterOperator.LessThanOrEqual:
case FilterOperator.Like:
case FilterOperator.Or:
{
buffer.AppendFormat("'{1}' {0} '{2}'", FilterOperator, operand1, operand2);
break;
}
case FilterOperator.Between:
{
buffer.AppendFormat("'{1}' <= '{0}' <= '{2}'", operand1, operand2, operand3);
break;
}
case FilterOperator.Cast:
{
buffer.AppendFormat("({1}){0}", operand1, operand2);
break;
}
case FilterOperator.InList:
{
buffer.AppendFormat("'{0}' in {", operand1);
for (int ii = 1; ii < operands.Count; ii++)
{
if (ii < operands.Count - 1)
{
buffer.Append(", ");
}
buffer.AppendFormat("'{0}'", operands[ii].ToString());
}
buffer.Append("}");
break;
}
case FilterOperator.RelatedTo:
{
buffer.AppendFormat("'{0}' ", operand1);
string referenceType = operand2;
if (operands.Count > 1)
{
LiteralOperand literalOperand = operands[1] as LiteralOperand;
if (literalOperand != null)
{
INode node = nodeTable.Find(literalOperand.Value.Value as NodeId);
if (node != null)
{
referenceType = Utils.Format("{0}", node);
}
}
}
buffer.AppendFormat("{0} '{1}'", referenceType, operand2);
if (operand3 != null)
{
buffer.AppendFormat("Hops='{0}'", operand3);
}
break;
}
}
return(buffer.ToString());
}
/// <summary>
/// Returns the subscription filter to use.
/// </summary>
public EventFilter GetFilter()
{
ContentFilter whereClause = new ContentFilter();
ContentFilterElement element1 = whereClause.Push(FilterOperator.OfType, EventTypeId);
EventFilter filter = new EventFilter();
for (int ii = 0; ii < Fields.Count; ii++)
{
filter.SelectClauses.Add(Fields[ii].Operand);
if (Fields[ii].FilterValue != Variant.Null)
{
LiteralOperand operand = new LiteralOperand();
operand.Value = Fields[ii].FilterValue;
ContentFilterElement element2 = whereClause.Push(Fields[ii].FilterOperator, Fields[ii].Operand, operand);
element1 = whereClause.Push(FilterOperator.And, element1, element2);
}
}
filter.WhereClause = whereClause;
return filter;
}
/// <summary>
/// Pushes a new element onto the stack.
/// </summary>
/// <param name="op">The filter operator.</param>
/// <param name="operands">The operands.</param>
/// <returns></returns>
public ContentFilterElement Push(FilterOperator op, params object[] operands)
{
// check if nothing more to do.
if (operands == null || operands.Length == 0)
{
throw ServiceResultException.Create(StatusCodes.BadInvalidArgument, "ContentFilterElement does not have an operands.");
}
// create the element and set the operator.
ContentFilterElement element = new ContentFilterElement();
element.FilterOperator = op;
for (int ii = 0; ii < operands.Length; ii++)
{
// check if a FilterOperand was provided.
FilterOperand filterOperand = operands[ii] as FilterOperand;
if (filterOperand != null)
{
element.FilterOperands.Add(new ExtensionObject(filterOperand));
continue;
}
// check for reference to another ContentFilterElement.
ContentFilterElement existingElement = operands[ii] as ContentFilterElement;
if (existingElement != null)
{
int index = FindElementIndex(existingElement);
if (index == -1)
{
throw ServiceResultException.Create(StatusCodes.BadInvalidArgument, "ContentFilterElement is not part of the ContentFilter.");
}
ElementOperand operand = new ElementOperand();
operand.Index = (uint)index;
element.FilterOperands.Add(new ExtensionObject(operand));
continue;
}
// assume a literal operand.
LiteralOperand literalOperand = new LiteralOperand();
literalOperand.Value = new Variant(operands[ii]);
element.FilterOperands.Add(new ExtensionObject(literalOperand));
}
// insert the new element at the begining of the list.
m_elements.Insert(0, element);
// re-number ElementOperands since all element were shifted up.
for (int ii = 0; ii < m_elements.Count; ii++)
{
foreach (ExtensionObject extension in m_elements[ii].FilterOperands)
{
if (extension != null)
{
ElementOperand operand = extension.Body as ElementOperand;
if (operand != null)
{
operand.Index++;
}
}
}
}
// return new element.
return(element);
}
