Configure file upload for censhare Web
censhare chunks uploads for large files so that an interrupted upload can be resumed. Configure the upload settings and define default values for your network.
Context
This configuration affects the upload of files and creation of assets from files in censhare Web. The upload processes in censhare Web and the censhare Java Client are different. This article is about the file upload in censhare Web.
In this configuration, you can define the default values for file uploads. You can take into account the quality of your network and the expected size of the files users are uploading. In case the upload fails, users can resume where it.
Prerequisites
You need root domain access to configure the system asset of your censhare system.
Introduction
When users create assets from files, these are uploaded to the censhare Server.
The files that users upload to the censhare server can be very large, for example video files, high resolution images or ZIP archives. For these files, the upload takes some time depending on the network bandwidth. The longer the upload will last, the higher is the possibility of failure. Especially, mobile networks are prone to connection timeouts which may cause the upload process to fail.
In case an upload fails, users have to restart it from the beginning (that means, from the very first byte). To avoid that, censhare Web uses chunked upload. Files to be uploaded are split into smaller chunks. These are transferred one-by-one to the server. If an upload fails, users can resume from the last successfully transmitted chunk.
After successfully uploading all chunks, censhare merges them into the original file. Until then, the chunks for one file are kept in a temporary upload asset.
The upload settings define the chunk size and how many chunks will be uploaded simultaneously. Both affect the upload behavior. They should be adjusted according to the expected file size and the connection quality of your users.
Configuration
Go to the System asset and open it in an asset page. There, go to the "Overview" tab and edit the "Properties" widget by clicking the pencil button. The Edit Properties icon appears in the header of the widget when you move the cursor over it: 
In the dialog, look for the File upload settings section. The available settings are described in the table below. Read also the "Remarks and recommendations" section at the end of this article.
Field | Default | Remarks |
Chunk size (bytes) | 3145728 | Next to this field, you see the size converted to KB or MB. The value is calculated as you start typing. The default value corresponds to 3.00 MB. |
Simultaneous file chunks | 3 | This value defines, how many chunks will be uploaded at the same time. A value between 1 and 10 is allowed. |
Simultaneous files | 3 | This value defines, how many files will be uploaded at the same time. If users add more files than this at once, these will be queued. A value between 1 and 10 is allowed. |
Prioritize first/last chunk | Yes | This option is only for test and internal purposes. Do not change. |
Number of retries on failure | 10 | This value defines how many times censhare tries to resume an upload in progress automatically. If it continues to fail, censhare quits the process and shows an error message. The upload can then be resumed manually. |
When finished, click OK to close the dialog. To save the changes to the System asset, click SAVE or "SAVE & CLOSE". The new settings become effective after refreshing your browser.
Notes and best practices
Maximum number of chunks: The file upload handles a maximum number of 1.000 chunks per file. If you define a small chunks size and/or files are so large that more than this number of chunks would be created, censhare ignores the configured chunk size value and creates 1.000 chunks, no matter what the resulting chunk size is.
Recommended chunk size: The best chunk size depends mainly on the network stability and bandwidth, but also on the file size of the uploaded files. Therefore, it is almost impossible to have default settings that cover all cases. Most likely, if you are working in an enterprise network, stability and bandwidth are very high, whereas in a distributed environment both are considerably lower. Keep in mind that small chunks result in a greater fragmentation of the uploaded file. Use it only as a means to achieve a more robust upload process. Splitting a file into small chunks does not increase the upload speed, if the bandwidth is limited. On the other side, mobile networks, even if they are fast, are more prone to network timeouts due to weak signals. In these cases, chunked upload can save your users time and frustration, when they have to restart uploading a very large file.
Simultaneous chunks/files upload: The simultaneous upload of chunks and files can speed up the upload process, if set according to the connection bandwidth. censhare can process multiple chunks/files at the same time and thus avoid bottlenecks during the upload. The multiplied values of "Simultaneous chunks" and "Simultaneous files" represents the maximum number of simultaneous connections to the server. This value should not exceed 10 (for example: 3 x 3 = 9). However, if an upload fails due to connection timeouts, all chunks/files that are being uploaded at this moment, have to be uploaded again. This may be counter-productive to the intended purpose of the chunked upload.