Updates docs

docs/source/releasenotes.rst

@@ -5,18 +5,23 @@ Release notes
 V2.7.2
 ======
 
-This is mainly a bug-fix release of version 2.7.1.
+This is a bug-fix release of version 2.7.1 with small improvements.
 
 * This release includes a workaround to a problem with the limits of int
   in the XMLRPC protocol (the protocol uses int32).
   This problem avoids setting a memory size or file size larger than the maximum int32 value.
   A full solution to this problem requires modifications in the Moodle plugin side.
-  This workaround switches the size limit to the jail server local size limit when the problem is found.
-
-* Adds new tools to the installer: bc, mypy, pycodestyle, and pydocstyle.
+  This temporal workaround switches the size limit to the jail server local size limit
+  when the problem is found.
 
 * Uses long long int to represent memory a file size.
 
+* The installer includes the tool bc and new modules when installing python3:
+  mypy, pycodestyle, and pydocstyle.
+
+* The system checks for a change in the SSL certificate, reloading it if changed.
+  This allows updating certificates without stopping the service.
+
 V2.7.1
 ======
 

docs/source/requirements.rst

@@ -59,3 +59,59 @@ and the throughput will decrease drastically.
 Our tests indicate that the 32-bit O.S. uses less memory and CPU than the 64-bit version.
 Remember that you can add (or remove) VPL-Jail-systems to a VPL installation online.
 
+
+Network requirements
+====================
+
+This section describes the network requirement to use the execution server with the VPL plugin.
+
+Connections that must be available
+----------------------------------
+
+* From the user machine to the Moodle Server.
+  The client machine that runs the browser must have access to the Moodle server.
+  This is the obvious connection when the user interacts with Moodle.
+  Notice that is highly recommended to use cyphered connections (HTTPS),
+  that is the Moodle server must have a certificate signed by a known authority
+  and the user must use an HTTPS connection (the URL to the Moodle server must start with "https://").
+
+* From the Moodle Server to the Execution Server (Jail server).
+  The VPL plugin in Moodle requires sending requests to the execution server.
+  Notice that is highly recommended to use cyphered connections (HTTPS),
+  that is the Execution server must have a certificate signed by a known authority
+  and the VPL plugin must use an HTTPS connection (the URL to the execution server must start with "https://").
+
+* From the user machine to the Execution Server (Jail server).
+  The client machine that runs the browser must have access to the Execution server.
+  When an execution/evaluation is requested, the execution server requires a connection from the browser
+  to know that the user is there and if needed a connection to allow interactions with the running program.
+  These connections are WebSocket and it is highly recommended to use cyphered connections (WSS),
+  that is the Execution server must have a certificate signed by a known authority.
+
+Proxies
+-------
+
+If your network is not using a transparent proxy you must:
+
+* Configure the user machines to use the proxy properly.
+  Notice that your proxy must be compatible with WebSocket.
+
+* Configure the VPL plugin (Moodle administration VPL plugin settings) to use the proxy
+  to access properly to the executions servers.
+
+If your network is using a transparent proxy it must be compatible with WebSocket.
+
+Load balancer
+-------------
+
+The architecture of the connections of the execution server seems to not allow to use of a load balancer
+to access a cluster of execution servers.
+Notice that the execution server that runs a task receive several requests from the Moodle server
+and the client machine to manage the task.
+
+Private network
+---------------
+
+The system does not require external connections,
+then there are is no restriction to install all elements (clients, Moodle server and execution servers)
+in a private network.