MSMQ 大文件发送
在默认情况下msmq 3.0（windows xp ,windows 2003）最大单个消息(Message size)大小4M;（包括正文和全部指定属性的消息的大小不能超过 4 MB。 来自windows 2003帮助文件的说明。）
4M的限制对于一些普通的应用来说已经足够，而且作为消息传递，报文交换，我们推荐的是不要使用超过1M大小的报文。这样可以很好的利用网络带宽，和提高系统的处理性能。 但对于一些特别少数的应用仍然存在大报文的需求，而msmq作为一个消息中间件有很多优势。所以我们还是要想办法使用他，或是扩展他的功能。
下面就我在网上和通过一些网友的帮助整理了一些突破这个4M限制方法。
1.通过修改注册表(regedit)HKLM\SOFTWARE\Microsoft\MSMQ\Parameters\ 加添一个MaxMessageSize DWORD值大小默认4M(0x00400000)最大16M(x00F00000)，通过试验发现最大只能是16M左右，如果在改大，再调用程序的是否会报错
using (System.Messaging.MessageQueue mq = new System.Messaging.MessageQueue(".\\private$\\mq3"))
{
System.Messaging.Message msg = new System.Messaging.Message();
msg.BodyStream = new FileStream("e:\\CodeSmithProfessional-40.msi", FileMode.Open);
mq.Send(msg);
}
private void SendFile(string fileName, string queuePath)
{
int i;
int count = 0;
int msgNumber = 0;
int chunkSize = 4194000;
//Open an existing queue
MessageQueue queue = new MessageQueue(queuePath);
System.Messaging.Message msg = new System.Messaging.Message();
MessageQueueTransaction t = new MessageQueueTransaction();
t.Begin();
try
{
//Open the file for reading
using (FileStream fs = File.OpenRead(fileName))
{
// while there are bytes
while ((i = fs.ReadByte()) != -1)
{
// if count has reached size, send message
if (count >= chunkSize)
{
msgNumber++;
msg.AppSpecific = msgNumber;
//Send the messsage
queue.Send(msg,t);
string nextMsgId = msg.Id;
count = 0;
//Create a new message
msg = new System.Messaging.Message();
msg.CorrelationId = nextMsgId;
}
msg.BodyStream.WriteByte((byte)i);
count++; // from the original file
}
msgNumber++;
msg.AppSpecific = msgNumber;
//Send the last message
queue.Send(msg, t);
t.Commit();
}
}
catch (Exception ex)
{
Console.WriteLine(ex);
}
finally
{
//release queue resources
queue.Close();
}
}
private void ReceiveFile(string fileName, string queuePath)
{
byte[] data;
int length;
//Open an existing queue
MessageQueue queue = new MessageQueue(queuePath);
try
{
//Open file for writing
using (FileStream fs = File.OpenWrite(fileName))
{
//Receive the first message
System.Messaging.Message msg = queue.Receive(new TimeSpan(0, 0, 0, 1));
while (msg != null)
{
//Get the Lenght of the message body stream
length = Convert.ToInt32(msg.BodyStream.Length);
//Create a buffer to hold the stream in memory
data = new byte[length];
//Read the body stream
msg.BodyStream.Read(data, 0, length);
//Write the buffer into the file
fs.Write(data, 0, length);
//Receive following message
msg = queue.Receive(new TimeSpan(0, 0, 0, 1));
}
}
}
catch (Exception ex)
{
Console.WriteLine(ex);
}
finally
{
//release queue resources
queue.Close();
}
}
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4M的限制对于一些普通的应用来说已经足够，而且作为消息传递，报文交换，我们推荐的是不要使用超过1M大小的报文。这样可以很好的利用网络带宽，和提高系统的处理性能。
using (System.Messaging.MessageQueue mq = new System.Messaging.MessageQueue(".\\private$\\mq3")) {
System.Messaging.Message msg = new System.Messaging.Message(); msg.BodyStream = new FileStream("e:\\CodeSmithProfessional-40.msi", FileMode.Open); mq.Send(msg); } 2.消息分段发送，通过Message.ID,Message.CorrelationId关联，分割多个固定大小的消息.
private void SendFile(string fileName, string queuePath) { int i; int count = 0; int msgNumber = 0; int chunkSize = 4194000; //Open an existing queue MessageQueue queue = new MessageQueue(queuePath); System.Messaging.Message msg = new System.Messaging.Message(); MessageQueueTransaction t = new MessageQueueTransaction(); t.Begin(); try {
//Open the file for reading using (FileStream fs = File.OpenRead(fileName)) { // while there are bytes while ((i = fs.ReadByte()) != -1) { // if count has reached size, send message if (count >= chunkSize) { msgNumber++; msg.AppSpecific = msgNumber; //Send the messsage queue.Send(msg,t); string nextMsgId = msg.Id; count = 0; //Create a new message msg = new System.Messaging.Message(); msg.CorrelationId = nextMsgId; } msg.BodyStream.WriteByte((byte)i); count++; // from the original file } msgNumber++; msg.AppSpecific = msgNumber; //Send the last message queue.Send(msg, t); t.Commit(); } } catch (Exception ex) { Console.WriteLine(ex); } finally { //release queue resources queue.Close(); } }private void ReceiveFile(string fileName, string queuePath) { byte[] data; int length; //Open an existing queue MessageQueue queue = new MessageQueue(queuePath); try { //Open file for writing using (FileStream fs = File.OpenWrite(fileName)) { //Receive the first message System.Messaging.Message msg = queue.Receive(new TimeSpan(0, 0, 0, 1)); while (msg != null) { //Get the Lenght of the message body stream length = Convert.ToInt32(msg.BodyStream.Length); //Create a buffer to hold the stream in memory data = new byte[length]; //Read the body stream msg.BodyStream.Read(data, 0, length); //Write the buffer into the file fs.Write(data, 0, length); //Receive following message msg = queue.Receive(new TimeSpan(0, 0, 0, 1)); } } } catch (Exception ex) { Console.WriteLine(ex); } finally { //release queue resources queue.Close(); } } 3.使用BizTalk MSMQ Adapter,支持消息分段(segmentationSupport=true),前提队列必须是事务性(transactional=true)，MaxMessageSize最大可以4G，试验证实一个通过passthru方式处理一个200M的文件，处理占用大量cpu和IO外，BizTalk MessageBox数据也更大400M（200M日志文件，200M数据文件）。注意：通过方法2实现的分段，在用BizTalk接收会存在问题，BizTalk不会帮组合成一个大文件处理。
4.使用BizTalk提供的一个LargeMessage api可以以编成方式实现对大报文的处理，处理方式和方法3类似。并且可以实现和BizTalk兼容。
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