\item \textbf{Searching}. Video assets can be searched by keywords and the results must be ordered by their relevance. The search can be done in the whole set of videos or in a particular category.
\end{itemize}
-\textit{Internal authentication} is for users that applied for an account by the \textit{Registration} page. There are situations when the platform must be integrated with other services or sites. For example in our university we use P2P-Tube to share videos of technical presentations, courses or social events. We also have Moodle learning platform where students already have an account, so it was desired that users can authenticate on P2P-Tube we the same account credentials from Moodle. This has been achieved thorough LDAP which permits students to authenticate on both sites with the same user name and password, without requiring them to create an additional account. Another way to make users skip signing up is by using OpenID, a standard protocol which allows them to sign in through an account from another site. However, this third party site must support OpenID. So, for example, users that already have an account on Yahoo!, Google, Twitter or WordPress can securely sign in with the same user names and passwords from that accounts. When users log in for the first time using external authentication, like LDAP or OpenID, they must complete their profile.
+\textit{Internal authentication} is for users that applied for an account by the \textit{Registration} page. There are situations when the platform must be integrated with other services or sites. For example in our university we use P2P-Tube to share videos of technical presentations, courses or social events. We also have Moodle learning platform where students already have an account, so it was desired that users can authenticate on P2P-Tube with the same account credentials from Moodle. This has been achieved thorough LDAP which permits students to authenticate on both sites with the same user name and password, without requiring them to create an additional account. Another way to make users skip signing up is by using OpenID, a standard protocol which allows them to sign in through an account from another site. However, this third party site must support OpenID. So, for example, users that already have an account on Yahoo!, Google, Twitter or WordPress can securely sign in with the same user names and passwords from that accounts. When users log in for the first time using external authentication, like LDAP or OpenID, they must complete their profile.
Users can upload video assets through an upload mechanism described in the next subsection.
An user uploads a video file, referred here as \textit{raw video file}, to a web server and may also provide additional information about it, like title, description, tags etc.. When video upload is finished the process of content ingestion is started by the web server by sending a content ingestion request to a CIS. This is done directly, if the system has a single CIS, or indirectly via a CIS Load Balancer (CIS-LB), which forwards the request to one CIS from a pool of several CIS machines. By doing load balancing, the indirect request method provides scalability because more content ingestion jobs can run in parallel, allowing more users to add content simultaneously to the platform. By these means availability is also increased, the system becoming fault tolerant in case of CIS failures.
-Note that sending content ingestion request is transparent for the web server. There is no difference for it if this is done directly to a CIS or indirectly through a CIS-LB. This simplifies implementation of the web server and hides the abstraction of content ingestion from it.
+Note that sending content ingestion requests is transparent for the web server. There is no difference for it if this is done directly to a CIS or indirectly through a CIS-LB. This simplifies implementation of the web server and hides the abstraction of content ingestion from it.
\begin{figure}[h]
\begin{center}
In the end of the content ingestion process all other Content Ingestion Servers from the system must be aware of the new torrent files in order to seed them. First of all, the new torrent files need to be locally accessible to them, so all torrent files can be shared by CIS machines on a \textit{distributed file system} such as NFS, LustreFS or GlusterFS. The overhead of using shared storage between CIS machines shouldn't affect performance, even if NFS is used, which serves files through a single machine. This is because torrent files are very small so concurrently accessing more files on the shared file system can affect performance in a negligible manner.
-When the web server is notified about the job completion (10) a seed request must arrive to each CIS so that they can start seeding the new torrent files available in the distributed file system. This request is originated from the web server and there is no need to do this on a single CIS system, because this is already done in step 8 from Figure \ref{fig:content-ingestion}, so the web server can be configured to skip this redundant step from its configuration. In a multiple CIS system this step is mandatory for ensuring high availability of the new video assets. Thus, a \textbf{seed request} is sent from web server to CIS-LB, which forwards this message to all CIS from its jurisdiction. Upon reception they will start seeding requested torrent files which are located in the distributed file system.
\ No newline at end of file
+When the web server is notified about the job completion (10) a seed request must arrive to each CIS so that they can start seeding the new torrent files available in the distributed file system. This request is originated from the web server and there is no need to do this on a single CIS system, because this is already done in step 8 from Figure \ref{fig:content-ingestion}, so the web server can be configured to skip this redundant step from its configuration. In a multiple CIS system this step is mandatory for ensuring high availability of the new video assets. Thus, a \textbf{seed request} is sent from web server to CIS-LB, which forwards this message to all CIS from its jurisdiction. Upon reception they will start seeding requested torrent files which are located in the distributed file system.
+
+There may be situations when a seed request is lost by a CIS. For instance, a CIS is temporarily down or it has a temporary network failure and does not receive a seed request from CIS-LB. After recovery it will not know about the existence of new torrent files. This can lead to availability problems, so to solve this a CIS periodically scans the torrent directory for new torrent files.
+
+When a CIS daemon starts running it begins seeding all torrent files from the distributed file system.
\ No newline at end of file
projects / living-lab-site.git / blobdiff