本主题适用于 Windows Workflow Foundation 4。
在有些情况下，用户或工作流管理员可能需要手动检查持久保存的工作流实例的状态。SqlWorkflowInstanceStore 提供一个有关 Instances 表的视图，公开以下四列：
ReadWritePrimitiveDataProperties
WriteOnlyPrimitiveDataProperties
ReadWriteComplexDataProperties
WriteOnlyComplexDataProperties
基元数据属性指的是那些具有“通用”的 .NET Framework 类型（如 Int32 和 String）的属性，而复杂数据属性指的是其他所有类型。在此代码示例的后面提供了基元类型的完整枚举。
ReadWrite 属性指的是那些在加载实例时返回到工作流运行时的属性。WriteOnly 属性将写入到数据库，然后再也不会读取。
此示例提供使用户能够将基元数据属性反序列化的代码。假定有一个从 ReadWritePrimitiveDataProperties 或 WriteOnlyPrimitiveDataProperties 列读取的字节数组，此代码将二进制大型对象 (BLOB) 转换为 <XName, object> 类型的 Dictionary（其中的每个键/值对表示一个属性名及其对应的值）。
此示例没有演示如何将复杂数据属性反序列化，因为当前不支持该操作。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.IO.Compression;
using System.Xml.Linq;
using System.Xml;
using System.Globalization;
using System.Data.SqlClient;
namespace PropertyReader
{
class Program
{
const string ConnectionString = @"Data Source=localhost;Initial Catalog=Persistence;Integrated Security=True;Asynchronous Processing=True";
static void Main(string[] args)
{
string queryString = "SELECT TOP 10 * FROM [System.Activities.DurableInstancing].[Instances]";
using (SqlConnection connection =
new SqlConnection(ConnectionString))
{
SqlCommand command =
new SqlCommand(queryString, connection);
connection.Open();
SqlDataReader reader = command.ExecuteReader();
byte encodingOption;
while (reader.Read())
{
if (reader["ReadWritePrimitiveDataProperties"] != DBNull.Value)
{
encodingOption = (byte)reader["EncodingOption"];
Console.WriteLine("Printing the ReadWritePrimitiveDataProperties of the instance with Id:" + reader["InstanceId"]);
foreach (KeyValuePair<XName, object> pair in (Dictionary<XName, object>)ReadDataProperties((byte[])reader["ReadWritePrimitiveDataProperties"], encodingOption))
{
Console.WriteLine("{0}, {1}" , pair.Key, pair.Value);
}
Console.WriteLine();
}
//if (reader["ReadWriteComplexDataProperties"] != DBNull.Value)
//{
// encodingOption = (byte)reader["EncodingOption"];
// Console.WriteLine("Printing the ReadWriteComplexDataProperties of the instance with Id:" + reader["InstanceId"]);
// foreach (KeyValuePair<XName, object> pair in (Dictionary<XName, object>)ReadDataProperties((byte[])reader["ReadWriteComplexDataProperties"], encodingOption))
// {
// Console.WriteLine("{0}, {1}", pair.Key, pair.Value);
// }
// Console.WriteLine();
//}
if (reader["WriteOnlyPrimitiveDataProperties"] != DBNull.Value)
{
encodingOption = (byte)reader["EncodingOption"];
Console.WriteLine("Printing the WriteOnlyPrimitiveDataProperties of the instance with Id:" + reader["InstanceId"]);
foreach (KeyValuePair<XName, object> pair in (Dictionary<XName, object>)ReadDataProperties((byte[])reader["WriteOnlyPrimitiveDataProperties"], encodingOption))
{
Console.WriteLine("{0}, {1}", pair.Key, pair.Value);
}
Console.WriteLine();
}
//if (reader["WriteOnlyComplexDataProperties"] != DBNull.Value)
//{
// encodingOption = (byte)reader["EncodingOption"];
// Console.WriteLine("Printing the WriteOnlyComplexDataProperties of the instance with Id:" + reader["InstanceId"]);
// foreach (KeyValuePair<XName, object> pair in (Dictionary<XName, object>)ReadDataProperties((byte[])reader["WriteOnlyComplexDataProperties"], encodingOption))
// {
// Console.WriteLine("{0}, {1}", pair.Key, pair.Value);
// }
// Console.WriteLine();
//}
}
// Call Close when done reading.
reader.Close();
}
Console.ReadLine();
}
static Dictionary<XName, object> ReadDataProperties(byte[] serializedDataProperties, byte encodingOption)
{
if (serializedDataProperties != null)
{
Dictionary<XName, object> propertyBag = new Dictionary<XName, object>();
bool isCompressed = (encodingOption == 1);
using (MemoryStream memoryStream = new MemoryStream(serializedDataProperties))
{
// if the instance state is compressed using GZip algorithm
if (isCompressed)
{
// decompress the data using the GZip
using (GZipStream stream = new GZipStream(memoryStream, CompressionMode.Decompress))
{
// create an XmlReader object and pass it on to the helper method ReadPrimitiveDataProperties
using (XmlReader reader = XmlDictionaryReader.CreateBinaryReader(stream, XmlDictionaryReaderQuotas.Max))
{
// invoke the helper method
ReadPrimitiveDataProperties(reader, propertyBag);
}
}
}
else
{
// if the instance data is not compressed
// create an XmlReader object and pass it on to the helper method ReadPrimitiveDataProperties
using (XmlReader reader = XmlDictionaryReader.CreateBinaryReader(memoryStream, XmlDictionaryReaderQuotas.Max))
{
// invoke the helper method
ReadPrimitiveDataProperties(reader, propertyBag);
}
}
return propertyBag;
}
}
return null;
}
// reads the primitive data properties from the XML stream
// invoked by the ReadDataProperties method
static void ReadPrimitiveDataProperties(XmlReader reader, Dictionary<XName, object> propertyBag)
{
const string xmlElementName = "Property";
if (reader.ReadToDescendant(xmlElementName))
{
do
{
// get the name of the property
reader.MoveToFirstAttribute();
string propertyName = reader.Value;
// get the type of the property
reader.MoveToNextAttribute();
PrimitiveType type = (PrimitiveType)Int32.Parse(reader.Value, CultureInfo.InvariantCulture);
// get the value of the property
reader.MoveToNextAttribute();
object propertyValue = ConvertStringToNativeType(reader.Value, type);
// add the name and value of the property to the property bag
propertyBag.Add(propertyName, propertyValue);
}
while (reader.ReadToNextSibling(xmlElementName));
}
}
// invoked by the ReadPrimitiveDataProperties method
// Given a property value as parsed from an XML attribute, and the .NET Type of the Property, recreates the actual property value
// (e.g. Given a property value of "1" and a PrimitiveType of Int32, this method will return an object of type Int32 with value 1)
static object ConvertStringToNativeType(string value, PrimitiveType type)
{
switch (type)
{
case PrimitiveType.Bool:
return XmlConvert.ToBoolean(value);
case PrimitiveType.Byte:
return XmlConvert.ToByte(value);
case PrimitiveType.Char:
return XmlConvert.ToChar(value);
case PrimitiveType.DateTime:
return XmlConvert.ToDateTime(value, XmlDateTimeSerializationMode.RoundtripKind);
case PrimitiveType.DateTimeOffset:
return XmlConvert.ToDateTimeOffset(value);
case PrimitiveType.Decimal:
return XmlConvert.ToDecimal(value);
case PrimitiveType.Double:
return XmlConvert.ToDouble(value);
case PrimitiveType.Float:
return float.Parse(value, CultureInfo.InvariantCulture);
case PrimitiveType.Guid:
return XmlConvert.ToGuid(value);
case PrimitiveType.Int:
return XmlConvert.ToInt32(value);
case PrimitiveType.Long:
return XmlConvert.ToInt64(value);
case PrimitiveType.SByte:
return XmlConvert.ToSByte(value);
case PrimitiveType.Short:
return XmlConvert.ToInt16(value);
case PrimitiveType.String:
return value;
case PrimitiveType.TimeSpan:
return XmlConvert.ToTimeSpan(value);
case PrimitiveType.Type:
return Type.GetType(value);
case PrimitiveType.UInt:
return XmlConvert.ToUInt32(value);
case PrimitiveType.ULong:
return XmlConvert.ToUInt64(value);
case PrimitiveType.Uri:
return new Uri(value);
case PrimitiveType.UShort:
return XmlConvert.ToUInt16(value);
case PrimitiveType.XmlQualifiedName:
return new XmlQualifiedName(value);
case PrimitiveType.Null:
case PrimitiveType.Unavailable:
default:
return null;
}
}
// .NET Types which SQL Workflow Instance Store considers to be Primitive. Any other .NET type not listed in this enumeration is a "Complex" property.
enum PrimitiveType
{
Bool = 0,
Byte,
Char,
DateTime,
DateTimeOffset,
Decimal,
Double,
Float,
Guid,
Int,
Null,
Long,
SByte,
Short,
String,
TimeSpan,
Type,
UInt,
ULong,
Uri,
UShort,
XmlQualifiedName,
Unavailable = 99
}
}
}