在自定义任务中引发和定义事件
Integration Services 运行时引擎提供了一组事件，这些事件提供验证和执行任务时任务进度的状态。 IDTSComponentEvents 接口用于定义这些事件，并且该接口可作为 Validate 和 Execute 方法的参数提供给任务。
此外，还有另一组在 IDTSEvents 接口中定义的事件，TaskHost 可代表任务引发这些事件。 TaskHost 将引发在验证和执行之前或之后发生的事件，而任务则引发在执行和验证期间发生的事件。
创建自定义事件
自定义任务开发人员可通过在其 EventInfo 方法的重写实现中创建新的 InitializeTask 来定义新的自定义事件。 创建 EventInfo 后，可使用 Add 方法将其添加到 EventInfos 集合。 Add 方法的方法签名如下所示：
public void Add(string eventName, string description, bool allowEventHandlers, string[] parameterNames, TypeCode[] parameterTypes, string[] parameterDescriptions);
下面的代码示例演示自定义任务的 InitializeTask 方法，在该自定义任务中，创建了两个自定义事件并设置了其属性。 然后，将新事件添加到 EventInfos 集合。
第一个 自定义事件具有 eventName 为“OnBeforeIncrement”，并在 更新初始值后描述 “Fires”。下一个参数 true 值指示此事件应允许创建事件处理程序容器来处理事件。 事件处理程序是一个可向任务提供包和服务中的结构的容器，像其他诸如包、序列、ForLoop 和 ForEachLoop 的其他容器一样。 当 allowEventHandlers 参数为true时，DtsEventHandler将为事件创建对象。 为事件定义的所有参数现在均可在 DtsEventHandler 的变量集合中用于 DtsEventHandler。
public override void InitializeTask(Connections connections,
VariableDispenser variables, IDTSInfoEvents events,
IDTSLogging log, EventInfos eventInfos,
LogEntryInfos logEntryInfos, ObjectReferenceTracker refTracker)
{
this.eventInfos = eventInfos;
string[] paramNames = new string[1];
TypeCode[] paramTypes = new TypeCode[1]{TypeCode.Int32};
string[] paramDescriptions = new string[1];
paramNames[0] = "InitialValue";
paramDescriptions[0] = "The value before it is incremented.";
this.eventInfos.Add("OnBeforeIncrement",
"Fires before the task increments the value.",
true,paramNames,paramTypes,paramDescriptions);
this.onBeforeIncrement = this.eventInfos["OnBeforeIncrement"];
paramDescriptions[0] = "The value after it has been incremented.";
this.eventInfos.Add("OnAfterIncrement",
"Fires after the initial value is updated.",
true,paramNames, paramTypes,paramDescriptions);
this.onAfterIncrement = this.eventInfos["OnAfterIncrement"];
}
Public Overrides Sub InitializeTask(ByVal connections As Connections, _
ByVal variables As VariableDispenser, ByVal events As IDTSInfoEvents, _
ByVal log As IDTSLogging, ByVal eventInfos As EventInfos, _
ByVal logEntryInfos As LogEntryInfos, ByVal refTracker As ObjectReferenceTracker)
Dim paramNames(0) As String
Dim paramTypes(0) As TypeCode = {TypeCode.Int32}
Dim paramDescriptions(0) As String
Me.eventInfos = eventInfos
paramNames(0) = "InitialValue"
paramDescriptions(0) = "The value before it is incremented."
Me.eventInfos.Add("OnBeforeIncrement", _
"Fires before the task increments the value.", _
True, paramNames, paramTypes, paramDescriptions)
Me.onBeforeIncrement = Me.eventInfos("OnBeforeIncrement")
paramDescriptions(0) = "The value after it has been incremented."
Me.eventInfos.Add("OnAfterIncrement", _
"Fires after the initial value is updated.", True, _
paramNames, paramTypes, paramDescriptions)
Me.onAfterIncrement = Me.eventInfos("OnAfterIncrement")
End Sub
引发自定义事件
通过调用 FireCustomEvent 方法引发自定义事件。 下面的代码行引发了一个自定义事件。
componentEvents.FireCustomEvent(this.onBeforeIncrement.Name,
this.onBeforeIncrement.Description, ref arguments,
null, ref bFireOnBeforeIncrement);
componentEvents.FireCustomEvent(Me.onBeforeIncrement.Name, _
Me.onBeforeIncrement.Description, arguments, _
Nothing, bFireOnBeforeIncrement)
示例
下面的示例演示了一个任务，该任务在 InitializeTask 方法中定义了一个自定义事件，再将该自定义事件添加到 EventInfos 集合，然后通过调用 FireCustomEvent 方法在其 Execute 方法中引发该自定义事件。
[DtsTask(DisplayName = "CustomEventTask")]
public class CustomEventTask : Task
{
public override DTSExecResult Execute(Connections connections,
VariableDispenser variableDispenser, IDTSComponentEvents componentEvents,
IDTSLogging log, object transaction)
{
bool fireAgain;
object[] args = new object[1] { "The value of the parameter." };
componentEvents.FireCustomEvent( "MyCustomEvent",
"Firing the custom event.", ref args,
"CustomEventTask" , ref fireAgain );
return DTSExecResult.Success;
}
public override void InitializeTask(Connections connections,
VariableDispenser variableDispenser, IDTSInfoEvents events,
IDTSLogging log, EventInfos eventInfos,
LogEntryInfos logEntryInfos, ObjectReferenceTracker refTracker)
{
string[] names = new string[1] {"Parameter1"};
TypeCode[] types = new TypeCode[1] {TypeCode.String};
string[] descriptions = new string[1] {"Parameter description." };
eventInfos.Add("MyCustomEvent",
"Fires when my interesting event happens.",
true, names, types, descriptions);
}
}
<DtsTask(DisplayName = "CustomEventTask")> _
Public Class CustomEventTask
Inherits Task
Public Overrides Function Execute(ByVal connections As Connections, _
ByVal variableDispenser As VariableDispenser, _
ByVal componentEvents As IDTSComponentEvents, _
ByVal log As IDTSLogging, ByVal transaction As Object) _
As DTSExecResult
Dim fireAgain As Boolean
Dim args() As Object = New Object(1) {"The value of the parameter."}
componentEvents.FireCustomEvent("MyCustomEvent", _
"Firing the custom event.", args, _
"CustomEventTask" , fireAgain)
Return DTSExecResult.Success
End Function
Public Overrides Sub InitializeTask(ByVal connections As Connections, _
ByVal variableDispenser As VariableDispenser,
ByVal events As IDTSInfoEvents,
ByVal log As IDTSLogging, ByVal eventInfos As EventInfos, ByVal logEnTryInfos As LogEnTryInfos, ByVal refTracker As ObjectReferenceTracker)
Dim names() As String = New String(1) {"Parameter1"}
Dim types() As TypeCode = New TypeCode(1) {TypeCode.String}
Dim descriptions() As String = New String(1) {"Parameter description."}
eventInfos.Add("MyCustomEvent", _
"Fires when my interesting event happens.", _
True, names, types, descriptions)
End Sub
End Class
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