I am trying to send and receive process gzip-ed data from server on my client device application (not web).
I am sending gzip-ed content and on client side, I have following method that returns WebResponse:
protected override WebResponse GetWebResponse(WebRequest request)
{
WebResponse res = base.GetWebResponse(request);
if (((System.Net.HttpWebResponse)(res)).ContentEncoding.Contains("gzip"))
{
Stream responseStream = res.GetResponseStream();
responseStream = new GZipStream(responseStream, CompressionMode.Decompress);
}
//This returns g-ziped content as WebResponse, but I need to return
//above decompressed responseStream as WebResponse, how do I do that?
return res;
}
I am new to this but I am thinking that intercepting every response comming to my app in GetWebResponse is excellent centralized spot to decompress all responses. But the problem is how to pass the decompressed stream as response back?
Much appreciated
Related
I am from the old world that think webapi should return a strong typed object and let json serialization return data.
However, recently we got this requirement:
We have a sql table which has more than 500 columns.
The customer always want to return all the columns.
Our c# code does nothing other than reading the SqlDatareader, convert the reader to a c# object and return result.
In this case, wouldn't better to do this (example copied from another stackoverflow post). Basically just return a stream? Does returning a stream still considered to be anti-pattern?
public HttpResponseMessage SomeMethod(List<string> someIds)
{
HttpResponseMessage resp = new HttpResponseMessage();
resp.Content = new PushStreamContent(async (responseStream, content, context) =>
{
await CopyBinaryValueToResponseStream(responseStream, someIds);
});
return resp;
}
private static async Task CopyBinaryValueToResponseStream(Stream responseStream, int imageId)
{
// PushStreamContent requires the responseStream to be closed
// for signaling it that you have finished writing the response.
using (responseStream)
{
using (SqlConnection connection = new SqlConnection(connectionString))
{
await connection.OpenAsync();
using (SqlCommand command = new SqlCommand("SELECT 500 columns FROM [StupidWideTable] WHERE ....", connection))
{
.....
using (SqlDataReader reader = await command.ExecuteReaderAsync(CommandBehavior.SequentialAccess))
{
if (await reader.ReadAsync())
{
if (!(await reader.IsDBNullAsync(0)))
{
using (Stream data = reader.GetStream(0))
{
// Asynchronously copy the stream from the server to the response stream
await data.CopyToAsync(responseStream);
}
}
}
}
}
}
}// close response stream
}
Does returning a stream still considered to be anti-pattern?
Well, that depends on what you want to do. For example, if you want to return a 500 if the SQL server fails partway through, then you shouldn't return a stream.
Streaming results works fine on ASP.NET, but it's important to note that all headers (including the response status code) are sent before the stream begins. So you'll send an immediate 200 when you start streaming the result, and if there's an error later on there's no way to go back in time and change that to a 500. Or add some kind of Continue header.
In other words, yes it's supported; but you lose all the benefits of model binding, content negotiation, exception handlers, etc., because you're bypassing that whole pipeline.
I have a .net core 2.1 api application that will download a file from a remote location based on the file name. Here is the code:
static public class FileDownloadAsync
{
static public async Task DownloadFile(string filename)
{
//File name is 1GB.zip for testing
Stopwatch stopwatch = new Stopwatch();
stopwatch.Start();
using (HttpClient client = new HttpClient())
{
string url = #"http://speedtest.tele2.net/" + filename;
using (HttpResponseMessage response = await client.GetAsync(url, HttpCompletionOption.ResponseHeadersRead))
using (Stream readFrom = await response.Content.ReadAsStreamAsync())
{
string tempFile = $"D:\\Test\\{filename}";
using (Stream writeTo = File.Open(tempFile, FileMode.Create))
{
await readFrom.CopyToAsync(writeTo);
}
}
stopwatch.Stop();
Debug.Print(stopwatch.Elapsed.ToString());
}
}
}
This is working great, it will pull a 1 gig file down in about 50 seconds. Well within the required download time. I have hard coded a test file to download in this code for testing as well as storage location--these values will ultimately come from a config file when moved into production. Here is the API endpoint that calls this function:
[HttpGet("{fileName}")]
public async Task<string> GetFile(string fileName)
{
await FileDownloadAsync.DownloadFile(fileName);
return "Done";
}
So getting the file from a remote location down to the local server is not a problem. I need some help/guidance on re-posting this file to another API. Once the file is downloaded, there is some work done on the file to prepare it for upload (the files are all MP4 files), and once that work is done, I need to post it to another API for more proprietary processing. Here is the API end point data I have:
POST: /batch/requests Allocates resources to start new batch transcription. Use this method to request[work] on the input
audio data. Upon the accepted request, the response provides
information about the associated request ID and processing status.
Headers: Authorization: Authorization token
Accept: application/json
Content-Type: Indicates the audio format. The value must be:
audio/x-wav;codec=pcm;bit=16;rate=8000;channels=1
audio/x-wav;codec=pcm;bit=16;rate=16000;channels=1
audio/x-raw;codec=pcm;bit=16;rate=8000;channels=1
audio/x-raw;codec=pcm;bit=16;rate=16000;channels=1
video/mp4
Content-Length (optional): The size of the input voice file. Not
required if a chunked transfer is used.
Query string parameters (required):
profileId: one of supported (see GET profiles) customerId: the id of
the customer. A string of minimum 1 and up to 250 alphanumeric, dot
(.) and dash (-) characters.
So I will set the Content-Type to video/MP4 for processing. Note that if the input size is not used if a chunked transfer is used.
Right now, I am more concerned with just posting (streaming) the file in a non-chunked format while we await for more information on what they consider "chunking" a file.
So I am looking for help on steaming the file from disk to the endpoint. Everything I am running across for .net core API is creating the API to download the file from a POST like a Razor page or Angular page--I already have that. I just need some help on "re-posting" to another API.
Thanks
Using the HttpClient you open a stream to the file, create a content stream, set the necessary headers and post to the endpoint
Stream file = File.Open(filepath, FileMode.Open);
var content = new StreamContent(file);
content.Headers.ContentType = new MediaTypeHeaderValue("video/MP4");
client.DefaultRequestHeaders.Add("Authorization", "token here");
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json");
using (HttpResponseMessage response = await client.PostAsync(url, content)) {
//...
}
I need to send a gzipped byte array over HTTPS. I searched the web and only thing ı can found is SharpGIS.GZipWebClient.
However, the problem is - this third party solution only works with WebClient which allow you to send only String data.
(I'm on Windows Phone 8. Most of the WebClient methods do not exist.)
Any ideas to solve this problem?
Edit:
This is how I tried the POST JSON data over HTTPS using SharpGIS;
WebClient webClient = new SharpGIS.GZipWebClient();
webClient.Headers["Accept-Encoding"] = "gzip";
var uri = new Uri(pUrl, UriKind.Absolute);
webClient.UploadStringCompleted += new UploadStringCompletedEventHandler(wc_UploadStringCompleted);
webClient.UploadStringTaskAsync(uri, jsonAsString);
But it doesn't compresses the string as well(as using OpenWriteSync method).
You write the post data in the OpenWriteCompleted handler, like this:
void webClient_OpenWriteCompleted(object sender, OpenWriteCompletedEventArgs e)
{
Stream s = e.Result;
s.Write(jsonAsByteArray, 0, jsonAsByteArray.Length);
s.Flush();
s.Close();
}
You should also add the appropriate error handling.
I'm trying to implement an output cache in WebApi that can cache the responses already processed by filters and generate responses that are not processed by formatters.
From what I've seen ActionFilterAttribute's OnActionExecuting and OnActionExecuted are execute before the serialization formatters and so if you cache a response, at a cache hit you will respond the exact same content and that content will be serialized again to transmission.
As a possible solution in MVC I think that you can do this by implementing a IResultFilter that override OnResultExecuted by caching the serialized response. With this approach I don't know how to intercept the request handling to avoid the serialization formatters, I think that a possible solution to intercept is create a custom ActionResult to be handled directly by IResultFilter. Please note that this solution is not suitable for me because I'm implementing OutputCache in a WebApi application.
While writing the response, formatters in Web API come into action for HttpContents of type ObjectContent only.
In you OnActionExecuted method, you could force the serialization to happen by doing something like below and then set the response content as StreamContent (this way the formatters wouldn't be coming into picture):
An example below:
public override void OnActionExecuted(HttpActionExecutedContext actionExecutedContext)
{
HttpResponseMessage response = actionExecutedContext.Response;
if (response != null && response.IsSuccessStatusCode)
{
ObjectContent originalContent = response.Content as ObjectContent;
if (originalContent != null)
{
MemoryStream ms = new MemoryStream();
// NOTE:
// 1. We are forcing serialization to occur into a buffered stream here
// 2. This can cause exception. You can leave it as it is and Web API's exception handling mechanism should
// do the right thing.
originalContent.CopyToAsync(ms).Wait();
// reset the position
ms.Position = 0;
StreamContent newContent = new StreamContent(ms);
// Copy the headers
foreach (KeyValuePair<string, IEnumerable<string>> header in originalContent.Headers)
{
newContent.Headers.TryAddWithoutValidation(header.Key, header.Value);
}
//dispose the original content
originalContent.Dispose();
//TODO: cache this new httpcontent 'newContent' (so we are caching both serialized body + headers too)
//Set the response
//NOTE: This newContent will not hit the formatters
actionExecutedContext.ActionContext.Response.Content = newContent;
}
}
}
I've been racking my brain for a couple of days now on how to approach a new requirement.
I have two websites. The first one lets the user fill out an application. The second website is an internal website use to manage the users applications. I need to develop a "web service" that sends the application data from website 1 to website 2 and return a response to website 2 of success or failure. I have never done a web service before and I'm a bit confused on where to start. I've been reading various examples online but they all seem to be just a starting point for building a webservice... no specific examples.
So for posting the data website 1, what would my controller method look like? Do I use Json to post the data to website 2? What would and example of that look like? Is there some form of redirect in the method that points to website 2?
So for posting the response back to website 2 what would that controller method look like? I assume I would use Json again to send the response back to website 1? Is there some form of redirect in the method that points back to website 1?
I would use JSON and POST the application to the web service.
First I am assuming the application data is contained in some type of object. Use JSON.Net to serialize the object into JSON. It will look something like the following code.
var application = new Application();
string serializedApplication = JsonConvert.Serialize(application);
Second is to POST the code your endpoint(webservice, mvc action). To this you'll need to make a HTTPRequest to the endpoint. The following code is what I use to make to POST the code.
public bool Post(string url, string body)
{
//Make the post
ServicePointManager.ServerCertificateValidationCallback = (sender, certificate, chain, errors) => true;
var bytes = Encoding.Default.GetBytes(body);
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
Stream stream = null;
try
{
request.KeepAlive = false;
request.ContentLength = bytes.Length;
request.ContentType = "application/x-www-form-urlencoded";
request.Timeout = -1;
request.Method = "POST";
stream = request.GetRequestStream();
stream.Write(bytes, 0, bytes.Length);
}
finally
{
if (stream != null)
{
stream.Flush();
stream.Close();
}
}
bool success = GetResponse(request);
return success;
}
public bool GetResponse(HttpWebRequest request)
{
bool success;
using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
{
using (Stream responseStream = response.GetResponseStream())
{
if (response.StatusCode != HttpStatusCode.OK && response.StatusCode != HttpStatusCode.Created)
{
throw new HttpException((int)response.StatusCode, response.StatusDescription);
}
var end = string.Empty;
using (StreamReader reader = new StreamReader(responseStream))
{
end = reader.ReadToEnd();
reader.Close();
success = JsonConvert.DeserializeObject<bool>(end);
}
response.Close();
}
}
return success;
}
So now you have can POST JSON to an endpoint and receive a response the next step is to create the endpoint. The following code will get you started on an endpoint in mvc that will receive an application and process it.
[HttpPost]
public ActionResult SubmitApplication()
{
//Retrieve the POSTed payload
string body;
using (StreamReader reader = new StreamReader(Request.InputStream))
{
body = reader.ReadToEnd();
reader.Close();
}
var application = JsonConvert.Deserialize<Application>(body);
//Save the application
bool success = SaveApplication(application);
//Send the server a response of success or failure.
return Json(success);
}
The above code is a good start. Please note, I have not tested this code.
You have obviously more than one client for the data & operations. so a service is what you are looking for.
ASP.NET MVC is a good candidate for developing RESTful services. If you (and your Manager) are ready to use beta version, Then Checkout ASP.NET-Web API.
If you want to stay with a stable product, Go for MVC3. you may need to write some custom code to return the data in XML as well as JSON to server different kind of clients. There are some tutorials out there.
So create a Service (ASP.NET MVC / WCF Service) .You may then create 2 client apps, one for the external clients and another for the Internal users. Both of this apps can call methods in the Service to Create/ Read the user accounts / or whatever operation you want to do.
To make the apps more interactive and lively , you may conside including a wonderful thing called SiganalR, which helps you to get some real time data without continuosly polling the data base/ middle tier very in every n seconds !