# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1494887834 -7200
# Node ID 55040ff1aba265f0d156252a6759e6f5daaa34e4
# Parent  09ac27220fe15dbe1a4f67286f354d2e75b21ef8
Added quota illustrations and an explicit introduction of the journal concept.

diff -r 09ac27220fe1 -r 55040ff1aba2 docs/wiki/Resources
--- a/docs/wiki/Resources	Sun Apr 02 22:15:30 2017 +0200
+++ b/docs/wiki/Resources	Tue May 16 00:37:14 2017 +0200
@@ -376,19 +376,95 @@
 === Quota Controls ===
 
 In contrast to each user's stored information which consolidates information
-related to that user's own schedule, the quota system consolidates information
-related to the schedules of one or more resources, thus enabling observations
-to be made about their collective usage.
+related to that user's own schedule in a section of the data store, the quota 
+system consolidates information related to the schedules of one or more 
+resources in a repository known as the journal, thus enabling observations to
+be made about their collective usage.
 
 First, consider a resource such as a car where an organiser of an event may be
 booking the car for travel purposes. A quota prevents the organiser from
 booking the resource too much and denying other users access to it.
 
+{{{#!graphviz
+//format=svg
+//transform=notugly
+digraph quota_users {
+  node [shape=box,fontsize="13.0",fontname="Helvetica",tooltip="Quota example"];
+  edge [tooltip="Quota example"];
+
+  subgraph {
+    rank=same;
+    reservation1 [label="Reservation from oliver.otter@example.com\nMonday at 10am",shape=folder,style=filled,fillcolor=cyan];
+    reservation2 [label="Reservation from oliver.otter@example.com\nTuesday at 10am",shape=folder,style=filled,fillcolor=cyan];
+    reservation3 [label="Reservation from oliver.otter@example.com\nWednesday at 10am",shape=folder,style=filled,fillcolor=cyan];
+  }
+
+  subgraph {
+    rank=same;
+    test1 [label="Within quota?",shape=ellipse,style=filled,fillcolor=gold];
+    test2 [label="Within quota?",shape=ellipse,style=filled,fillcolor=gold];
+    test3 [label="Within quota?",shape=ellipse,style=filled,fillcolor=gold];
+  }
+
+  subgraph {
+    rank=max;
+    quota [label="Quota for resource-car-pontiac@example.com",shape=folder];
+  }
+
+  reservation1 -> test1;
+  reservation2 -> test2;
+  reservation3 -> test3;
+
+  quota -> test1;
+  quota -> test2;
+  quota -> test3;
+}
+}}}
+
 Now consider a number of separate car resources. An organiser might attempt to
 get around any individual resource quota by booking a number of different cars.
+Since each car is only aware of its own usage, it would be unaware of the
+undesirable cumulative usage of all cars by the organiser.
+
 By grouping the resources together, the organiser will exhaust any quota set on
 the group of resources as they try and make reservations for the different
-members of the quota group.
+members of the quota group. Some additional measures are introduced as follows:
+
+{{{#!graphviz
+//format=svg
+//transform=notugly
+digraph quota_users {
+  node [shape=box,fontsize="13.0",fontname="Helvetica",tooltip="Quota example"];
+  edge [tooltip="Quota example"];
+
+  subgraph {
+    rank=same;
+    reservation1 [label="Reservation from oliver.otter@example.com\nMonday at 10am",shape=folder,style=filled,fillcolor=cyan];
+    reservation2 [label="Reservation from oliver.otter@example.com\nTuesday at 10am",shape=folder,style=filled,fillcolor=cyan];
+    reservation3 [label="Reservation from oliver.otter@example.com\nWednesday at 10am",shape=folder,style=filled,fillcolor=cyan];
+  }
+
+  subgraph {
+    rank=same;
+    car1 [label="resource-car-pontiac@example.com",shape=folder];
+    car2 [label="resource-car-cadillac@example.com",shape=folder];
+    car3 [label="resource-car-lexus@example.com",shape=folder];
+  }
+
+  test [label="Within common quota?",shape=ellipse,style=filled,fillcolor=gold];
+
+  subgraph {
+    rank=max;
+    journal [label="Quota for cars",shape=folder];
+  }
+
+  reservation1 -> car1 -> test;
+  reservation2 -> car2 -> test;
+  reservation3 -> car3 -> test;
+
+  journal -> test;
+}
+}}}
 
 ==== Initialising Quotas ====