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Forum Discussion
Dropbox API Hangs During Large File Download
Hey there! I am currently maintaining a mod launcher software that utilizes the Dropbox .NET C# API to allow users to download mod files.
Unfortunately, large files (usually 2-5GB in size) do n...
Greg-DB
Dropbox Staff
Dropbox StaffIf these are failing at about an hour, it does sound like it is due to the server timeout. There isn't an option to delay or prevent that.
Also "downloads are much slower using range requests than with the API" is a bit unclear as range requests are themselves do use the same API. Specifically, the DownloadAsync method calls the /2/files/download API endpoint, just like you would if you make requests directly to /2/files/download without using the SDK, whether or not you set a range. Range requests just include an additional header to request a specific portion of the file.
In any case, the connection speed to the Dropbox API servers depends on a number of different factors that can change over time or by location, such as the routing between the user's ISP and our servers, and may be slower than the ISP's rated speeds. Sometimes resetting or retrying the connection gets the client a different route and better speeds, but that is outside of our control. Some ISPs also throttle sustained connections so if you see an initial high connection speed followed by lower speeds, that could be the reason.
So, the best recommendation I can offer is to use range requests to continue downloading the rest of the data if a connection fails, and repeat as needed for up to one hour per connection.
Would you be able to provide a rough code sample to illustrate how this might be put into practice using the API? I've used range requests before, however I want to be certain that I am using them correctly in production code for the purposes of my launcher software.
- Greg-DB
I see the agent in the support ticket you referred to supplied this example:
HttpClient client = new HttpClient(); HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, "https://content.dropboxapi.com/2/files/download"); request.Headers.Add("Authorization", "Bearer " + accessToken); request.Headers.Add("Dropbox-API-Arg", "{\"path\":\"/test.txt\"}"); // in real code, use a JSON library to build this request.Headers.Add("Range", "bytes=0-10"); // this requests the first 11 bytes of the file HttpResponseMessage response = await client.SendAsync(request); Stream stream = response.Content.ReadAsStream(); // read from stream as desiredThat looks correct; the only additional thing you need to do to a /2/files/download call to request a specific range is add the "Range" header like that.
Greg-DB wrote:...
... request.Headers.Add("Range", "bytes=0-10"); // this requests the first 11 bytes of the file
......
Hi pear0533,
You don't actually need a range starting from zero. You can start with regular API call and if that breaks for some reason then go forward with range(s).
Let's say you have to download a file and start downloading it in regular way. At some moment transfer breaks, let say, at position 50 byte. Since headers are available, you know that the file is, let say, 200 bytes. So, you have downloaded 50 bytes already and there are some more to read. The easiest way is to set range to something like:
request.Headers.Add("Range", "bytes=50-");I.e. you're starting from byte 51 and onward. Now, let's say you got another 70 bytes successfully. Together with the first 50 bytes they form successfully downloaded block of 120 bytes. You can continue with:
request.Headers.Add("Range", "bytes=120-");I.e. you're starting again, but from byte 121 and onward. There is a big chance your download to complete successful. 😉 If not, continue the same logic further.
Hope this gives direction.
- Greg-DB
Thanks for the helpful added explanation Здравко!
pear0533 For reference, you can find more information on how to set ranges in the specification here. Note that Dropbox does not support setting multiple ranges in a single request though. That is, you can specify a single closed range like "bytes=0-10", or a single open range like "bytes=50-", but you can't specify multiple ranges at once like "bytes=0-999,4500-5499".
Hope this helps!
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