Introduction
Any LOB application requires document attachment facility; the user will demand to attach documents with records (i.e., scanned copies of sales invoices, purchase invoices etc.).
So, it is required to provide a common facility to upload and download documents. Here I am providing an implementation
of a TCP binding WCF service which is hosted in Windows Services. This service can be invoked by any WPF / WinForms based client application.
I will divide the solution in four parts:
- Interface Creation
- Service Creation
- Hosting Service (Windows Services)
- Consuming (Client)
Interface Creation
This is just a simple interface with two methods; first, it is required to reference and import the "System.ServiceModel" assembly.
Here, I am creating a different project for the interface as we can use the same DLL in the service class as well as the client.
[ServiceContract]
public interface IDocumentLibraryService
{
[OperationContract]
void UploadDocument(string fPath, byte[] data);
[OperationContract]
byte[] DownloadDocument(string fPath);
}
Service Creation
As we are creating a WCF service, it is required to add a reference to the interface "IDocumentLibraryService".
So, after adding the reference, I have inherited the DocumentLibraryService class from that interface and implemented both the methods.
Upload Document
The code to process the incoming stream is rather simple; storing the uploaded files to a single folder on
the disk and overwriting any existing files.
Download Document
Open the file, convert its contents into a byte array, and return it to the calling process /client.
public class DocumentLibraryService : IDocumentLibraryService.IDocumentLibraryService
{
public void UploadDocument(string fPath, byte[] data)
{
string filePath = fPath;
FileStream fs = new FileStream(filePath, FileMode.Create,
FileAccess.Write);
fs.Write(data, 0, data.Length);
fs.Close();
}
public byte[] DownloadDocument(string fPath)
{
string filePath = fPath;
using (FileStream fs = new FileStream(filePath, FileMode.Open,
FileAccess.Read, FileShare.Read))
{
byte[] buffer = new byte[fs.Length];
fs.Read(buffer, 0, (int)fs.Length);
return buffer;
}
}
}
Hosting Service
Create a Windows Service project (optionally, you can also host your service in a normal WinForms or WPF application),
add the above created service class, and open the channel in the OnStart method of the Windows Service. Close the channel in the OnStop method.
Here, I set the number of binding properties before opening the channel to make sure it works in the case of large files too.
Timeout property settings are required because if the client takes longer to upload a file it does not come up with a timeout exception.
To be honest, I have not played with these settings very much yet, so you will probably want to tweak these to your own situations.
After setting up all the properties, I add the endpoint to the service. I have selected the port 8000; in your case, you can select any.
Finally, the server is waiting for any client to create the channel at port no. 8000.
Note: If you have installed any firewall, anti virus, Windows firewall etc., then please make the exception entry into
it for your selected port. Also, the created Windows Service must have the security rights to access the specified folder or location on the disk.
To know more about how to create a Windows Service:
protected override void OnStart(string[] args)
{
StartWCFService();
}
void StartWCFService()
{
try
{
NetTcpBinding ntcp = new NetTcpBinding();
ntcp.MaxBufferPoolSize = 2147483647;
ntcp.MaxReceivedMessageSize = 2147483647;
ntcp.MaxBufferSize = 2147483647;
ntcp.ReaderQuotas.MaxStringContentLength = 2147483647;
ntcp.ReaderQuotas.MaxDepth = 2147483647;
ntcp.ReaderQuotas.MaxBytesPerRead = 2147483647;
ntcp.ReaderQuotas.MaxNameTableCharCount = 2147483647;
ntcp.ReaderQuotas.MaxArrayLength = 2147483647;
ntcp.SendTimeout = new TimeSpan(1, 10, 0);
ntcp.ReceiveTimeout = new TimeSpan(1, 10, 0);
svh = new ServiceHost(typeof(DocumentLibraryService));
((ServiceBehaviorAttribute)
svh.Description.Behaviors[0]).MaxItemsInObjectGraph = 2147483647;
svh.AddServiceEndpoint(
typeof(IDocumentLibraryService.IDocumentLibraryService),
ntcp,
"net.tcp://localhost:8000");
svh.Open();
}
catch (Exception e)
{
Trace.WriteLine(e.Message);
}
}
Consuming (Client)
Here, firstly, I have to add a reference to our interface DLL. After that, I have created
a channel between the client and the service after setting up all the properties for the binding.
ChannelFactory<IDocumentLibraryService.IDocumentLibraryService> scf;
scf = new ChannelFactory<IDocumentLibraryService.IDocumentLibraryService>(ntcp,
"net.tcp://localhost:8000");
IDocumentLibraryService.IDocumentLibraryService client;
client = scf.CreateChannel();
- Download: After calling the
downloaddocument function with the required parameters, it is required to save the downloaded document to a user defined location. - Upload: Here, first, we will ask the user for the file path to upload a document, and after converting that document into a byte array,
we will pass it to the
uploaddocument function.
Conclusion
As you can see, it is very easy to create a document download / upload WCF service which can be used across multiple applications.
I have not created the UI for the client, i.e., the one for asking the user for the file name to upload or download etc..
Please provide your valuable suggestions / criticisms / feedback.
