Wiki source code of Drools Integration

Last modified by Pierre Dubois on 2011/10/24 11:34

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Pierre Dubois 1.1 1 = Introduction =
2
3 In 3.0, there is the possibility to activate rules in Operations.
4
5 Rules is a new way to express some business coding that sometimes is more appropriate than procedural javascript.
6 Note that rules do not replace JavaScript, but in some cases is more efficient and more maintainable.
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8
9 By default, the rules management system uses JBoss Drools: [[http:~~/~~/www.jboss.org/drools>>http://www.jboss.org/drools]]
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11
12
13 = Using Rules in Operations =
14
15 A Rule based step can be added in operations:
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17 [[image:img53.png||alt="Rule operation Step"]]
18
19
20 An example of rules:
21
22
23 [[image:img52.png||alt="Rules based example"]]:
24
25
26 == Rules definitions ==
27
28 Rules can be
29
30 * inline: the rule (or rules) are defined directly in the step.
31 * knowledge base: the rules are defined in external files
32
33
34 == Objects added to the rule set ==
35
36 In an operation step, records (data) are added to the rule session.
37
38 * if the current record (data) is an entity, the entity is added
39 * if the data is a list of entities, all the entities are added in the rule session
40
41 == Setting values in Rules ==
42
43 In the "then" clause of rules, you can set properties:
44
45 {{code language="javascript"}}
46 $alarm.almPriority = "Low";
47 {{/code}}
48
49 == Calling Operations in Rules ==
50
51 You can call operations on objects that are defined in the Rules:
52
53 * if the operation has the "data" parameter defined as of type "Entity" of the same type, the operation is considered as an "instance" operation, and can be called directly on the object. Example:
54
55 {{code language="javascript"}}
56 $alarm.Save();
57 {{/code}}
58
59 * if the operation has different data defined as the case above, the operation can be called using the "Registry" object:
60
61 {{code language="javascript"}}
62 $alarm = Registry.rqServerMonitorAlarm.Trigger($monitor, "MEM_HIGH_0001");
63 {{/code}}
64
65
66 == Rules Examples ==
67
68 Here are some examples of rules. In those examples, you can see:
69
70 * accessing properties (with the mvel dialect)
71 * joining entities by reference
72 * inserting related entities in the rule session for further processing
73 * setting properties
74 * calling operation on entities
75 * using salience
76
77
78 {{code language="javascript"}}
79 package com.requea.rules;
80
81 import com.requea.entity.Registry;
82 import com.requea.entity.*;
83
84
85 rule"New monitor"
86 dialect"mvel"
87 when
88 $monitor : rqServerMonitor()
89 then
90 // eval server info
91 insert($monitor.rqServer);
92 // eval memory info
93 insert($monitor.rqHeapMemoryInfo);
94 end
95
96
97
98 rule"MEM_HIGH_0001 - When memory is too high"
99 dialect"mvel"
100 when
101 $mem : rqMemoryInfo(rqUsed > 0.9 * rqMax)
102 $monitor : rqServerMonitor(rqHeapMemoryInfo == $mem)
103 then
104 // trigger an alarm
105 $alarm = Registry.rqServerMonitorAlarm.Trigger($monitor, "MEM_HIGH_0001");
106 // this is a low priority alarm
107 $alarm.almPriority = "Low";
108 insert($alarm);
109 end
110
111
112
113 rule"MEM_HIGH_0001 - Memory Alarm on a production server"
114 dialect"mvel"
115 when
116 $server : rqRepoServerConfiguration(rqProduction == true)
117 $monitor : rqServerMonitor(rqServer == $server)
118 $alarm : rqServerMonitorAlarm(almPriority != "High", rqServerMonitor == $monitor)
119 then
120 // trigger an alarm
121 modify($alarm) {
122 // priority should be high
123 almPriority = "High";
124 }
125 end
126
127
128 rule"Save Alarms"
129 dialect"mvel"
130 salience -50
131 when
132 $alarm : rqServerMonitorAlarm()
133 then
134 // save the alarm
135 $alarm.Save();
136 end
137
138 {{/code}}
139
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141
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