我想你遇到的主要问题不在于同步异步方面吧?我感觉最困难的地方在于Silverlight不支持DataTable类,从而需要定义海量的DataContract
在大约2009年,即Silverlight2时,遇到了类似的问题,为了返回服务端的各种数据,Silverlight需要定义一大堆的DataContract,一个简单的功能往往就需要定义20~30种DataContract,稍微复杂的就不可想象了,很多天的工作就是定义DataContract,纯粹的体力活:(
当时搞出的解决办法是:"动态类型"+自定义序列化.大致如下:
服务端:
[ServiceContract]
public interface IDbService
{
[OperationContract]
string Query(string strSql);
}
public class DbService : IDbService
{
public string Query(string strSql)
{
DataTable rlt = QueryInternal(strSql);
string strCSV = SerializeToCSV(rlt);
return strCSV;
}
private DataTable QueryInternal(strSql)
{
// 这里从略,标准的查询数据库,返回一个DataTable结果集
return datatableResult;
}
// 格式化为CSV形式,这是拷贝当时写的代码,对于当时的应用,CSV这种简单格式已经足够了,如果你的应用复杂,可以用标准的SOAP,JSON等序列化
private string SerializeToCSV(DataTable dtShow)
{
// 生成形如"Name:字段标题1,字段标题2\nType:System.String, System.Int32\n字串数据1, 100\n字串数据,512"样式的CSV
StringBuilder sbCSV = new StringBuilder();
// Name & Type
StringBuilder sbName = new StringBuilder("Name:");
StringBuilder sbType = new StringBuilder("Type:");
foreach (DataColumn c in dtShow.Columns)
{
if (c.Ordinal > 0)
{
sbName.Append(',');
sbType.Append(',');
}
sbName.Append(c.ColumnName);
sbType.Append(c.DataType.FullName);
}
sbCSV.AppendFormat("{0}\n{1}\n", sbName, sbType);
// Data
foreach (DataRow dr in dtShow.Rows)
{
foreach (DataColumn c in dtShow.Columns)
{
if (c.Ordinal > 0) sbCSV.Append(',');
sbCSV.Append(dr[c]);
}
sbCSV.Append('\n');
}
return sbCSV.ToString();
}
}
客户端的关键在于反序列化,并生成动态数据类型
[ServiceContract]
public interface IDbService
{
[OperationContract(AsyncPattern = true)]
IAsnycResult BeginQuery(string strSql, AsyncCallback ac, object state);
string EndQuery(IAsnycResult);
}
// 怎么创建客户代理见前面的贴子,这里从略
private void foo()
{
IAsnycResult ar = client.BeginQuery("some sql here", null, null);
string rlt = client.EndQuery(ar);
// rlt是CSV格式,或你自己的序列化后的DataTable
// 下面要反序列化一下
TableCSV tcsv = new TableCSV();
List<object> listData = tcsv.Parse(strStat);
// 可以使用反射访问数值,或者直接呈现给DataGrid
yourDataGrid.ItemSource = listData;
}
TableCSV是用来反序列化,并生成动态类型,如果你用了复杂的序列化,这里用相应的反序列化就可以了
<pre>// 把CSV格式的字符串型数据,转换为Table形式.
public class TableCSV
{
public TableCSV()
{
}
// 分析
public List<Object> Parse(string strCSV)
{
// 所有列结构描述应在所有数据之前
bool bColDescFin = false;
// DataGridColumn属性正则表达式
Regex rgxProperties = new Regex(@"^(\w+):(.*)", RegexOptions.Singleline);
// 换行分隔,逐行处理
IEnumerable<string> queryLines = from line in strCSV.Split('\n') select line;
foreach (string strLine in queryLines)
{
Match m = rgxProperties.Match(strLine);
if (m.Success)
{
// 分析列结构
ParseColumns(m.Groups[1].Value, m.Groups[2].Value);
}
else
{
if (!bColDescFin)
{
// 列结构分析结束,动态构造类型
bColDescFin = true;
BuildType();
}
// 分析数据
ParseData(strLine);
}
}
return m_listData;
}
// 分析列结构
private void ParseColumns(string strE, string strColumns)
{
if (String.Compare(strE, "Name", StringComparison.OrdinalIgnoreCase) == 0)
{
// 分析列名称
m_listColumnName = new List<string>();
IEnumerable<string> queryColumns = from word in strColumns.Split(',') select word.Trim();
foreach (string strName in queryColumns)
{
m_listColumnName.Add(strName);
}
}
else if (String.Compare(strE, "Type", StringComparison.OrdinalIgnoreCase) == 0)
{
// 分析列数据类型
m_listColumnType = new List<Type>();
IEnumerable<string> queryColumns = from word in strColumns.Split(',') select word.Trim();
foreach (string strTypeName in queryColumns)
{
try
{
m_listColumnType.Add(Type.GetType(strTypeName, true));
}
catch (TypeLoadException ex)
{
string strbuf = String.Format("不可识别的数据类型\"{0}\"", strTypeName);
throw new Exception(strbuf, ex);
}
}
}
else
{
string strbuf = String.Format("不可识别的前缀描述符\"{0}\",目前仅支持\"Name\"和\"Type\"两个描述符", strE);
throw new Exception(strbuf);
}
}
private List<string> m_listColumnName;
private List<Type> m_listColumnType;
// 动态生成的类型
private Type m_tStatItem = null;
// 动态构造类型
private void BuildType()
{
try
{
AssemblyName asmName = new AssemblyName("AsmDynamic");
AssemblyBuilder asmBuilder = AppDomain.CurrentDomain.DefineDynamicAssembly(asmName, AssemblyBuilderAccess.Run);
ModuleBuilder mBuilder = asmBuilder.DefineDynamicModule("ModDynamic");
TypeBuilder tBuilder = mBuilder.DefineType("StatItem", TypeAttributes.Public);
for (int i = 0; i < m_listColumnName.Count; i++)
{
BuildProperty(tBuilder, m_listColumnName[i], m_listColumnType[i]);
}
m_tStatItem = tBuilder.CreateType();
}
catch (ArgumentOutOfRangeException ex)
{
string strbuf = String.Format("列名称和类型数目不匹配,列名称{0}个,类型{1}个", m_listColumnName.Count, m_listColumnType.Count);
throw new Exception(strbuf, ex);
}
}
private void BuildProperty(TypeBuilder tBuilder, string strProperty, Type tProperty)
{
// 内部变量
string strField = String.Format("m_{0}", strProperty);
FieldBuilder fldBuilder = tBuilder.DefineField(strField, tProperty, FieldAttributes.Private);
// 定义属性
PropertyBuilder pBuilder = tBuilder.DefineProperty(strProperty, PropertyAttributes.None, tProperty, null);
// get
string strGet = String.Format("get_{0}", strProperty);
MethodAttributes attrMethod = MethodAttributes.Public | MethodAttributes.SpecialName | MethodAttributes.HideBySig;
MethodBuilder mBuilder = tBuilder.DefineMethod(strGet, attrMethod, tProperty, Type.EmptyTypes);
ILGenerator il = mBuilder.GetILGenerator();
il.Emit(OpCodes.Ldarg_0);
il.Emit(OpCodes.Ldfld, fldBuilder);
il.Emit(OpCodes.Ret);
pBuilder.SetGetMethod(mBuilder);
// set
string strSet = String.Format("set_{0}", strProperty);
mBuilder = tBuilder.DefineMethod(strSet, attrMethod, null, new Type[] { tProperty });
il = mBuilder.GetILGenerator();
il.Emit(OpCodes.Ldarg_0);
il.Emit(OpCodes.Ldarg_1);
il.Emit(OpCodes.Stfld, fldBuilder);
il.Emit(OpCodes.Ret);
pBuilder.SetSetMethod(mBuilder);
}
// 分析数据
private void ParseData(string strData)
{
// 不处理空白行
if (strData.Trim() == String.Empty) return;
int n = 0;
string strValue = String.Empty;
try
{
// 创建对象
object objItem = Activator.CreateInstance(m_tStatItem);
IEnumerable<string> queryData = from word in strData.Split(',') select word.Trim();
foreach (string strbuf in queryData)
{
strValue = strbuf;
// 数据类型转换
object objValue = Convert.ChangeType(strbuf, m_listColumnType[n], null);
// 设定值
PropertyInfo pi = m_tStatItem.GetProperty(m_listColumnName[n]);
pi.SetValue(objItem, objValue, null);
n++;
}
m_listData.Add(objItem);
}
catch (ArgumentOutOfRangeException ex)
{
string strbuf = String.Format("定义了{0}列,该行数据不止{0}个:\n{1}", m_listColumnName.Count, strData);
throw new Exception(strbuf, ex);
}
catch (FormatException ex)
{
string strbuf = String.Format("数据格式不相符.\n列\"{0}\"标识为\"{1}\"类型\n\"{2}\"第{3}列\"{4}\"无法转换为\"{1}\"类型",
m_listColumnName[n], m_listColumnType[n], strData, n + 1, strValue);
throw new Exception(strbuf, ex);
}
}
// 结果数据
private List<object> m_listData = new List<object>();
}
