This document explains the download manager implementation inside OpenRAP container and the interaction with the plugins and plugin states for a content download with different stages in detail. While downloading a file(content) and the different possible scenarios which occurs and how to handle them to restart or resume from the state where we left before the interruption.
Download Manager
Download Manager Implementation
/*
* Below are the status for the download manager with different status
*/
enum STATUS {
Submitted = "SUBMITTED",
InProgress = "INPROGRESS",
Completed = "COMPLETED",
EventEmitted = "EVENTEMITTED"
}
/* Method to get the instance of the download manager */
getInstance = function(String pluginId) : DownloadManager {// create new instance of the download manager against plugin and return it.};
/*
This method will ensure that when the service is started/restarted updates the queue using data from download_queue database
*/
reconciliation = function() {
// Get the data from database where downloads which are not emitted the event
// Filter the documents
// Emit the events for download files which are not emitted the events
// Add the downloads to queue if the files are having status Submitted, In-Progress
};
/*
* Method to watch for the download queue whether it is running or not
*/
downloadQueueWatcher = function() {
// create a time interval which will check the health the download queue this should not fail
};
/*
* Method to queue the download of a file
* @param file - The file to download
* @param path - Path to download the file
* @return downloadId - The download id reference
*/
download = function(String file, String path) : String {// insert the download request with data to database// push the download request to queue // return the downloadId back};
/*
* Method to queue the download of a file
* @param file - The file to download
* @param path - Path to download the file
* @return downloadId - The download id reference
*/
download = function(String[] files, String folder) : String {
// insert the download request with data to database
// push the download request to queue
// return the downloadId back
};
/*
* Method to get the status of the download
* @param downloadId String
* @return Download object
*/
get = function(String downloadId) : DownloadObject {
// Read status of the request with downloadId and return downloadObject
};
/*
* Method to pause the download
* @param downloadId String
*/
pause = function(String downloadId) : Promise {
// call pause method with downloadId in the queue
};
/*
* Method to cancel the download
* @param downloadId String
*/
cancel = function(String downloadId) : Promise {
// remove the download row from database
// remove the download request from queue using downloadId
};
/*
* Method to pause all the downloads for the given plugin
* @param downloadId String
*/
pauseAll = function() : Promise {
// call pauseAll method on the queue and return the promise
};
/*
* Method to cancel all the downloads for the given plugin
* @param downloadId String
*/
cancelAll = function() : Promise {// get all the downloadIds which are not completed// call killDownload with all the downloadIds on the queue and return the promise
};
/*
* Method to list the download queue based on the status
* @param status String - The status of the download - Submitted, Complete, InProgress, Failed. Blank option will return all status
* @return Array - Array of download objects
*/
list = function(String status): DownloadObject[] {
// get the list of items from database if status is provided otherwise get all the status
};
// sample download object
{
id: String, // Download id
status: String, // Submitted, InProgress, Complete, Failed.
createdOn: Date,
updatedOn: Date,
stats: {
totalFiles: Number, // Total files to download
downloadedFiles: Number, // Total files downloaded so far
totalSize: Number, // Total number of bytes to download
downloadedSize: Number, // Total number of bytes downloaded so far
},
files: [{ // Status of each file within the given download
file: String, // File that is downloaded
source: String, // source from where it is downloaded
path: String, // Relative path where the file is downloaded to
size: Integer, // Total file size in bytes
downloaded: Integer // Downloaded until now
}]
}
Plugin
{
/*Below are content status when the content is submitted for dowload
*/
enum CONTENT_DOWNLOAD_STATUS {Submitted = "SUBMITTED",
Extracted = "EXTRACTED",
Indexed = "INDEXED"
}
}