在前两讲《初探.Net Remoting服务端 Loading Remtoing配置内容的过程 》《初探.Net Remoting客户端 Loading Remtoing配置内容的过程 》中,我已经分析了Remoting 的Sink机制，接下来，就提供一个具体的范例：CompressionSink（原始SourceCode源于Advanced .Net Remoting 1StED）。 CompressionSink通过在客户端和服务端各自插入一个数据压缩-解压缩的Sink。目的是希望减少大数据量传递对网络带宽的占用，提高传输效率。下载SourceCode ,BTW,这个压缩Sink相对比较稳定，大家可以在各自的项目中放心使用。:-)
详细设计：
提供一个Assembly： CompressionSink.dll
它包括：
客户端：
CompressionSink.CompressionClientSinkProvider类和CompressionSink.CompressionClientSink类
服务端：
CompressionSink.CompressionServerSinkProvider类和CompressionSink.CompressionServerSink类
压缩类：CompressionHelper
压缩内核：NZipLib库。
客户端的配置文件 ：
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<system.runtime.remoting>
<application>
<channels>
<channel ref="http">
<clientProviders>
<formatter ref="soap" />
<provider type="CompressionSink.CompressionClientSinkProvider, CompressionSink" />
</clientProviders>
</channel>
</channels>
<client>
<wellknown type="Service.SomeSAO, Service" url="http://localhost:5555/SomeSAO.soap" />
</client>
</application>
</system.runtime.remoting>
</configuration>
服务端的配置文件 ：
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<system.runtime.remoting>
<application>
<channels>
<channel ref="http" port="5555">
<serverProviders>
<provider type="CompressionSink.CompressionServerSinkProvider, CompressionSink" />
<formatter ref="soap"/>
</serverProviders>
</channel>
</channels>
<service>
<wellknown mode="Singleton" type="Service.SomeSAO, Service" objectUri="SomeSAO.soap" />
</service>
</application>
</system.runtime.remoting>
</configuration>
public class CompressionClientSinkProvider: IClientChannelSinkProvider 
{ 
private IClientChannelSinkProvider _nextProvider; public CompressionClientSinkProvider(IDictionary properties, ICollection providerData) 
{ // not yet needed 
} public IClientChannelSinkProvider Next { get { return _nextProvider; } set { _nextProvider = value; } } public IClientChannelSink CreateSink(IChannelSender channel, string url, object remoteChannelData) { // create other sinks in the chain IClientChannelSink next = _nextProvider.CreateSink(channel, url, remoteChannelData); // put our sink on top of the chain and return it return new CompressionClientSink(next); } 
} public class CompressionClientSink: BaseChannelSinkWithProperties, 2
IClientChannelSink 3
{ 4
private IClientChannelSink _nextSink; 5
6
public CompressionClientSink(IClientChannelSink next) 7
{ 8
_nextSink = next; 9
} 10
11
public IClientChannelSink NextChannelSink 12
{ 13
get { 14
return _nextSink; 15
} 16
} 17
18
19
public void AsyncProcessRequest(IClientChannelSinkStack sinkStack, 20
IMessage msg, 21
ITransportHeaders headers, 22
Stream stream) 23
{ 24
25
26
// generate a compressed stream using NZipLib 27
stream = CompressionHelper.getCompressedStreamCopy(stream); 28
29
// push onto stack and forward the request 30
sinkStack.Push(this,null); 31
_nextSink.AsyncProcessRequest(sinkStack,msg,headers,stream); 32
} 33
34
35
public void AsyncProcessResponse(IClientResponseChannelSinkStack sinkStack, 36
object state, 37
ITransportHeaders headers, 38
Stream stream) 39
{ 40
41
// deflate the response 42
stream = 43
CompressionHelper.getUncompressedStreamCopy(stream); 44
45
// forward the request 46
sinkStack.AsyncProcessResponse(headers,stream); 47
} 48
49
50
public Stream GetRequestStream(IMessage msg, 51
ITransportHeaders headers) 52
{ 53
return _nextSink.GetRequestStream(msg, headers); 54
} 55
56
57
public void ProcessMessage(IMessage msg, 58
ITransportHeaders requestHeaders, 59
Stream requestStream, 60
out ITransportHeaders responseHeaders, 61
out Stream responseStream) 62
{ 63
// generate a compressed stream using NZipLib 64
65
Stream localrequestStream = 66
CompressionHelper.getCompressedStreamCopy(requestStream); 67
68
Stream localresponseStream; 69
// forward the call to the next sink 70
_nextSink.ProcessMessage(msg, 71
requestHeaders, 72
localrequestStream, 73
out responseHeaders, 74
out localresponseStream); 75
76
// deflate the response 77
responseStream = 78
CompressionHelper.getUncompressedStreamCopy(localresponseStream); 79
80
} 81
} public class CompressionServerSinkProvider: IServerChannelSinkProvider 2
{ 3
private IServerChannelSinkProvider _nextProvider; 4
5
public CompressionServerSinkProvider(IDictionary properties, ICollection providerData) 6
{ 7
// not yet needed 8
} 9
10
public IServerChannelSinkProvider Next 11
{ 12
get { 13
return _nextProvider; 14
} 15
set { 16
_nextProvider = value; 17
} 18
} 19
20
public IServerChannelSink CreateSink(IChannelReceiver channel) 21
{ 22
// create other sinks in the chain 23
IServerChannelSink next = _nextProvider.CreateSink(channel); 24
25
// put our sink on top of the chain and return it 26
return new CompressionServerSink(next); 27
} 28
29
public void GetChannelData(IChannelDataStore channelData) 30
{ 31
// not yet needed 32
} 33
34
} using System; using System.Runtime.Remoting.Channels; using System.Runtime.Remoting.Messaging; using System.IO; namespace CompressionSink { public class CompressionServerSink: BaseChannelSinkWithProperties, IServerChannelSink { private IServerChannelSink _nextSink; public CompressionServerSink(IServerChannelSink next) { _nextSink = next; } public IServerChannelSink NextChannelSink { get { return _nextSink; } } public void AsyncProcessResponse(IServerResponseChannelSinkStack sinkStack, object state, IMessage msg, ITransportHeaders headers, Stream stream) { // compressing the response stream=CompressionHelper.getCompressedStreamCopy(stream); // forwarding to the stack for further processing sinkStack.AsyncProcessResponse(msg,headers,stream); } public Stream GetResponseStream(IServerResponseChannelSinkStack sinkStack, object state, IMessage msg, ITransportHeaders headers) { return null; } public ServerProcessing ProcessMessage(IServerChannelSinkStack sinkStack, IMessage requestMsg, ITransportHeaders requestHeaders, Stream requestStream, out IMessage responseMsg, out ITransportHeaders responseHeaders, out Stream responseStream) { // uncompressing the request Stream localrequestStream = CompressionHelper.getUncompressedStreamCopy(requestStream); // pushing onto stack and forwarding the call sinkStack.Push(this,null); Stream localresponseStream; ServerProcessing srvProc = _nextSink.ProcessMessage(sinkStack, requestMsg, requestHeaders, localrequestStream, out responseMsg, out responseHeaders, out localresponseStream); // compressing the response responseStream= CompressionHelper.getCompressedStreamCopy(localresponseStream); // returning status information return srvProc; } } } public class CompressionHelper 2
{ 3
4
/**//// <summary> 5
/// refactor by zendy 6
/// </summary> 7
/// <param name="inStream"></param> 8
/// <returns></returns> 9
public static Stream getCompressedStreamCopy(Stream inStream) 10
{ 11
MemoryStream outStream = new MemoryStream(); 12
Deflater mDeflater = new Deflater(Deflater.BEST_COMPRESSION); 13
DeflaterOutputStream compressStream = new DeflaterOutputStream(outStream,mDeflater); 14
15
byte[] buf = new Byte[4096]; 16
int cnt = inStream.Read(buf,0,4096); 17
while (cnt>0) { 18
compressStream.Write(buf,0,cnt); 19
cnt = inStream.Read(buf,0,4096); 20
} 21
compressStream.Finish(); 22
//modify by zendy //这个设置非常重要,否则会导致后续Sink在处理该stream时失败,在原来的源码中就是因为没有这个处理导致程序运行失败 23
outStream.Seek(0,SeekOrigin.Begin); 24
return outStream; 25
} 26
27
/**//// <summary> 28
/// refactor by zendy 29
/// </summary> 30
/// <param name="inStream"></param> 31
/// <returns></returns> 32
public static Stream getUncompressedStreamCopy(Stream inStream) 33
{ 34
InflaterInputStream unCompressStream = new InflaterInputStream(inStream); 35
MemoryStream outStream = new MemoryStream(); 36
int mSize; 37
Byte[] mWriteData = new Byte[4096]; 38
while(true) 39
{ 40
mSize = unCompressStream.Read(mWriteData, 0, mWriteData.Length); 41
if (mSize > 0) 42
{ 43
outStream.Write(mWriteData, 0, mSize); 44
} 45
else 46
{ 47
break; 48
} 49
} 50
unCompressStream.Close(); 51
//modify by zendy//这个设置非常重要,否则会导致后续Sink在处理该stream时失败,,在原来的源码中就是因为没有这个处理导致程序运行失败 52
outStream.Seek(0,SeekOrigin.Begin); 53
return outStream; 54
} 55
}
BTW，这个Sink还可以扩展，比如判断需要压缩Stream的大小，如果很大，就压缩，否则不压缩（可以在responseHeaders和requestHeaders添加是否 已经压缩的标记)