This is the first time I've used a webservice for anything so the question may be a little basic. Anyhow, I have a webservice that acts as a proxy to our vendors site. It simplifies the "screen scrape" that we would usually have to do. The webservice function looks like this:
namespace foo
{
public class MyService : WebService
{
[WebMethod]
public string UploadFile(System.IO.FileStream fileToUpload)
{
return _obj.Upload(fileToUpload);
}
}
}
The client throws an error when you try to give it the FileStream that the method asks for. In compilation somewhere, the webservice changed the type of the parameter from System.IO.FileStream to foo.FileStream. Does anyone have any ideas as to how I did this to myself?
Thanks in advance!
In .NET when you are making calls across application domains (as you are here), you can't pass data that is specific to that application domain.
The general version of this is that when you are making calls between two separate processes, you can't send information that is specific (i.e. only has significance in that context) to that process and expect it to have significance in the other process.
This is what you are doing with the filestream. The filestream is a handle to the file on the OS that is specific to a process. There is no guarantee that a process on the same computer, let alone a process on another machine will be able to understand this.
This being a web service, that's exactly the situation you have, as you have two processes on different machines.
To address the issue, the data you send has to be self-contained. In this specific case, that means sending the contents of the entire file.
You should change the parameter to a byte array, and then process the bytes appropriately in your method.
ASMX web services do not support the use of System.IO.Stream or any derived type of Stream. You would need WCF for this.
Related
Using WCF, .NET 4.5, Visual Studio 2015, and want to use per-session instancing, not singleton. The services provided are to be full-duplex, over tcp.net.
Suppose I have two machines, A & B...
B as a client, connects to a "service" provided as a WCF service on same machine B, and starts talking to it, call it object “X”. It ALSO connects to another instance of the same service, call it object “Y”
A as a client, wants to connect to, and use, exact same objects B is talking to, objects “X” and “Y”, except now it’s remote-remote, not local-remote.
“X” and “Y” are actually a video servers, and both have “state”.
Can I do this? How, when I’m a client, do I specify WHICH service instance I want to connect to?
Obviously, on machine "B", I could kludge this by having the services just be front-ends with no "state", which communicate with some processes running on "B", but that would require I write a bunch of interprocess code, which I hate.
Machine B is expected to be running 100's of these "video server" instances, each one being talked to by a local master (singleton) service, AND being talked to by end-user machines.
I realize this question is a bit generic, but it also addresses a question I could not find asked, or answered, on the Internets.
I just thought of one possible, but kludge-y solution: since the master service is a singleton, when service instance "X" is created by the end-user, it could connect to the singleton master service, through a proxy to the singleton. Then, the singleton can talk back to instance "X" over a callback channel. Yeah, that would work! messy, but possible.
I'd still like to know if end user A and end user B can both talk to the same (non-singleton) service instance on machine C through some funky channel manipulation or something. As I understand the rules of WCF, this simply isn't possible. Perhaps maybe if you're hosting the service yourself, instead of IIS, but even then, I don't think it's possible?
I've faced the same problem and solved it by creating two service references, one for the local one for the remote. Let's call it LocalServiceClient and RemoteServiceClient.
In a class, create a property called Client (or whatever you like to call it):
public LocalServiceClient Client {
get {
return new LocalServiceClient();
}
}
Okay this is for only one of them. Just create another now, and set which one to use with a compiler flag:
#if DEBUG
public LocalServiceClient Client {
get {
return new LocalServiceClient();
}
}
#else
public RemoteServiceClient Client {
get {
return new RemoteServiceClient();
}
}
#endif
Instantiate any instances of your Client using var keyword, so it will be implicitly-typed, or just use Client directly:
var client = Client;
client.DoSomething...
//or
Client.DoSomething...
This way, when you are working locally, it will connect to the local service, and on release configuration (make sure you are on Release when publishing) it will compile for the remote one. Make sure you have the exact same signature/code for both services though at the WCF-side.
There are also methods that you can dynamically do it in code, or like in web.config, they would also work for sure, but they are usually an overkill. You probably need to connect to local one in debugging, and the remote one in production, and this is going to give you exactly what you need.
I have a simple web service that looks something like this:
[WebMethod]
public OrderForecastItem GetOrderForecast(int shipTo, string catalogName, bool showPricing)
{
return OrderForecastManager.GetOrderForecast(shipTo, catalogName, showPricing);
}
I'm calling it from another place in a fairly simple way:
using (OrderForecastWS.OrderForecastWS service = new OurSite.Web.Reporting.OrderForecastWS.OrderForecastWS())
{
OrderForecastItem orderForecastItems = service.GetOrderForecast(2585432, "DENTAL", false);
}
After some gymnastics to get the systems to understand that I'm talking about the same type of objects on the client and server sides (I had to open the Reference.cs file inside my Web References, delete the generated OrderForecastItem and add a link to our real OrderForecastItem), the system runs and attempts to get the item.
Unfortunately, it now bombs during the service call, claiming:
Exception There is an error in XML document (1, 1113).(InvalidOperationException)
I can go to the web service in a browser, put in the same values, and I get a seemingly valid XML response. (It looks okay to me, and I ran it through the XML parser at W3Schools, and it cleared it.)
I think the numbers in the error are supposed to be the line and character number...but the browser seems to reformat the xml document, so I can't easily see what the original (1, 1113) location is.
I don't see an easy way to intercept the response and examine it, since it seems to be blowing up as soon as it gets it.
How can I debug this?
If you control the service, you can step into it. If it is a part of your solution and hosted in VS WebDev on your local box, just F11 from Visual Studio, if service is hosted remotely (eg by IIS on other computer) run remote debugging tool on service host msdn, and then you will be able to step in to the service remotely.
By the way, you can tell Visual Studio to re-use objects from referenced libraries for types from the service: just pick configure Service Reference from service context menu and tell which libraries to re-use.
On second thought this error may happen if returned XML could not be deserialized into your business object. May happen when class is changed on either side, or you are trying to use different version of business library than service is using.
If you use Firefox, I'd recommend Firebug. You'll be able to easily view the response from the website in its original format, which might get you closer to the line and position you're looking for.
I'm attempting to recycle an app pool on IIS6 programmatically through a web application. I have searched all over the net and found a bunch of solutions (Most involving impersonation) but none of them seem to work. The most common error I get is E_ACCESSDENIED despite entering a valid username and password. Can anybody point me in the right direction?
The solution I use for this sort of thing (Where you're trying to run a process from ASP.NET that needs administrative privileges) is the following:
Write whatever you need done as a Self hosted WCF service. Preferably an Http REST Service, so it's easy to call (even using just a browser for testing)
Make sure you service is run using an administrator account. You can use the task scheduler to make sure the service is running at all times as well as run using an Administrator account.
Execute methods on the service from your ASP.NET application using a WCF Client
And it works all the time no matter what "process" I'm trying to run from within an ASP.NET application.
Now as far are the details (code) is concerned let me know if you need help. The code below
is the code you'd have in a console application in order to make it a self hosted WCF Service.
In this case it's an Http service listening on port 7654.
static void Main(string[] args)
{
var webServiceHhost = new WebServiceHost(typeof(AppCmdService), new Uri("http://localhost:7654"));
ServiceEndpoint ep = webServiceHhost.AddServiceEndpoint(typeof(AppCmdService), new WebHttpBinding(), "");
var serviceDebugBehavior = webServiceHhost.Description.Behaviors.Find<ServiceDebugBehavior>();
serviceDebugBehavior.HttpHelpPageEnabled = false;
webServiceHhost.Open();
Console.WriteLine("Service is running");
Console.WriteLine("Press enter to quit ");
Console.ReadLine();
webServiceHhost.Close();
}
AppCmdService is a WCF Service class that looks like this (in my case). In your case you probably don't need a response from your service. In my case I'm getting a Json response. The actual implementation of what it is you're trying to do will be different obviously. But I'm assuming you already have that piece worked out. So simply call a method of that class from here.
[ServiceContract]
public class AppCmdService
{
[WebGet(UriTemplate = "/GetCurrentExcutingRequests/?", ResponseFormat= WebMessageFormat.Json)]
[OperationContract]
public IEnumerable<ExecutingRequestJson> GetCurrentExcutingRequests()
{
return CurrentExecutingRequestJsonProvider.GetCurrentExecutingRequests("localhost");
}
}
On your ASP.NET side, you don't really need a WCF client. All you need is a way to make an http call to the service. So you can simply use HttpWebRequest to make the call out to your service, which in turn execute your process.
Hope all of this makes sense?
Maybe this SO question helps you. There are several solutions (also for IIS6):
Restarting (Recycling) an Application Pool
IMHO the best you could do is to decide to go with a concrete approach an then when you run into an exception, to ask a concrete question with the source code of your approach. Otherwise it's just very vage to answer your question.
We are currently working on an API for an existing system.
It basically wraps some web-requests as an easy-to-use library that 3rd party companies should be able to use with our product.
As part of the API, there is an event mechanism where the server can call back to the client via a constantly-running socket connection.
To minimize load on the server, we want to only have one connection per computer. Currently there is a socket open per process, and that could eventually cause load problems if you had multiple applications using the API.
So my question is: if we want to deploy our API as a single standalone assembly, what is the best way to fix our problem?
A couple options we thought of:
Write an out of process COM object (don't know if that works in .Net)
Include a second exe file that would be required for events, it would have to single-instance itself, and open a named pipe or something to communicate through multiple processes
Extract this exe file from an embedded resource and execute it
None of those really seem ideal.
Any better ideas?
Do you mean something like Net.TCP port sharing?
You could fix the client-side port while opening your socket, say 45534. Since one port can be opened by only one process, only one process at a time would be able to open socket connection to the server.
Well, there are many ways to solve this as expressed in all the answers and comments, but may be the simpler way you can use is just have global status store in a place accesible for all the users of the current machine (may be you might have various users logged-in on the machine) where you store WHO has the right to have this open. Something like a "lock" as is used to be called. That store can be a field in a local or intranet database, a simple file, or whatever. That way you don't need to build or distribute extra binaries.
When a client connects to your server you create a new thread to handle him (not a process). You can store his IP address in a static dictionary (shared between all threads).
Something like:
static Dictionary<string, TcpClient> clients = new Dictionary<string, TcpClient>();
//This method is executed in a thread
void ProcessRequest(TcpClient client)
{
string ip = null;
//TODO: get client IP address
lock (clients)
{
...
if (clients.ContainsKey(ip))
{
//TODO: Deny connection
return;
}
else
{
clients.Add(ip, client);
}
}
//TODO: Answer the client
}
//TODO: Delete client from list on disconnection
The best solution we've come up with is to create a windows service that opens up a named pipe to manage multiple client processes through one socket connection to the server.
Then our API will be able to detect if the service is running/installed and fall back to creating it's own connection for the client otherwise.
3rd parties can decide if they want to bundle the service with their product or not, but core applications from our system will have it installed.
I will mark this as the answer in a few days if no one has a better option. I was hoping there was a way to execute our assembly as a new process, but all roads to do this do not seem very reliable.
I've been really interested in adding support for video podcasts to Media Browser.
I would like users to be able to navigate through the available video podcasts and stream them from the internets. That's really easy cause media player etc.. will happily play a file that lives in the cloud.
The problem is that I want cache these files locally so subsequent viewings of the same episode will not involve streaming and instead will play the local file.
So... I was thinking, why not host an HttpListener and as media player asks it for bits of the file, have the HttpListener download and store it locally. Next time a user plays the file we will already have portions of the file locally.
Does anyone know of example code that uses HttpListener for proxying?
EDIT
The idea would be only to proxy simple streamable content like MP3 or Mov.
The bounty will go to an actual implementation.
Here is the API I would like:
// will proxy a uri on the local port, if cacheFile exists it will resume the
// download from cacheFile.
// while the file is downloading it will be name cacheFile.partial, after the
// download is complete the file will be renamed to cacheFile.
// Example usage: ProxyFile("http://media.railscasts.com/videos/176_searchlogic.mov", 8000, #"c:\downloads\railscasts\176_searchlogic.mov")
//
// Directly after this call http://localhost:8000 will be the proxy stream, it will be playable locally.
void ProxyUri(Uri uri, int port, string cacheFile)
Edit 2
HttpListener is looking pretty unpromising I will probably need to do the work at a TCP socket level as HttpListeners seem to require the program runs as admin which is going to be really tricky.
I hadn't done anything with HttpListener before, so I thought this would be a nice little exercise to bring myself up to speed with it - and so it proved. I implemented it as a single ProxyListener class whose constructor takes the parameters of the ProxyUri function you specified. Once you obtain an instance, you start it listening (and potentially downloading) by calling its Start method. When you're done with it, call Cleanup.
There are one or two rough edges but basically it works as per your question. To test it, I built it up as a console application with a Program class which accepts input lines consisting of (uri, port, filename), space-separated, creates the ProxyListener instances and starts them. You can run this console application, type in a suitable line, and the downloader will start (printing out progress to console). Simultaneously you can e.g. fire up IE and fetch the file from the specified port, and you will be able to download it while the downloader is still working. The "uploader" progress will be printed to console, too.
I'm having a bit of trouble pasting it in here, maybe due to size (it's not that big, but bigger than the snippets you normally see here - the ProxyListener class is a tad under 200 lines). Does it sound interesting? If so, I'll post it to a pastebin and update this answer with a link.
Update: Posted as a gist.
Note that you will need Administrator privileges to run the program, since HttpListener requires this.
Update 2: Under certain circumstances, it is not necessary to have admin privileges to run HttpListener. See this link and this one. The idea is, if you can reserve an URL namespace during installation time, then the user does not have to have admin privileges if listening against that namespace.
Streaming was not designed to be saved, and also these protocols are very custom and very complex to implement, streaming sessions do lots of validation and synchronization which will be extremely difficult to imitate. Of course it is not an impossible task, but its fairly big task to do. Only other way is to read and save it as local media file, and use that as a reference. Because you can use windows media encoder to read stream and write stream data as local file, but it still may not allow you to do copy protected data.
Did you consider using HTTP proxy with caching features?
Like:
Apache httpd with mod_proxy and mod_cache
Squid
See also Web Cache # wikipedia
If you want your application to have such web cache component, I suggest you look for Web Cache implementation in .Net, and not code it from scratch.