Rules Schema Description

This topic lists the XML elements and attributes used to define the autoscaling rules in the Autoscaling Application Block. You can manually edit the XML data in a text or XML editor, or build your own tool to edit the configuration data. You can use the schema information contained in this topic when you edit the data manually, or when you design your own custom UI to edit this data.

If you installed the Autoscaling Application Block in your Visual Studio project by using NuGet, you can find the AutoscalingRules.xsd schema file in the root folder of the project.

The rules file has the following top-level structure.

<rules xmlns=
    https://schemas.microsoft.com/practices/2011/entlib/autoscaling/rules
  enabled="true">
  <constraintRules>
    ...
  </constraintRules>

  <reactiveRules>
    ...
  </reactiveRules>
  
  <operands>
    ...
  </operands>
</rules>

The rules Element

The top-level rules element has three optional child elements: the constraintRules element, the reactiveRules element, and the operands element (if there is a reactiveRules element, there must also be an operands element).

The enabled attribute of the rules element is a global flag that you can use to disable all rules evaluation in the Autoscaling Application Block. Its default value is true.

The constraintRules Element

The constraintRules element contains one or more rule elements that define constraint rules. Each rule element contains an optional actions element and an optional timetable element. The actions element contains one or more range elements.

The following snippet shows an example of a constraintRules element. For more examples, see the topic "Defining Constraint Rules."

<constraintRules>
  <rule name="Weekly Rule" description="Example weekly rule" rank="10" 
    enabled="true">
    <timetable startTime="06:00:00" duration="12:00:00" endDate="2011-12-15" 
      utcOffset="-08:00">
      <weekly days="Saturday Sunday" />
    </timetable>
  </rule>
  ...
</constraintRules>

Attributes of the rule Element

The following table describes the attributes of the rule element that defines a constraint rule. This rule element is a child of the constraintRules element.

Attributes of the range Element

The following table describes the attributes of the range element that defines a constraint rule. This element is a child of the actions element that is a child of the rule element. Each range must identify a unique target.

Attributes and Children of the timetable Element

The following table describes the attributes of the timetable element. The timetable element is an optional child of the rule element. If there is no timetable, the rule is assumed to always be in effect.

The timetable element contains one of the following child elements.

The following table lists the attributes of the weekly element.

The following table lists the attributes of the monthly element.

The following table lists the attributes of the relativeMonthly element.

The following table lists the attributes of the yearly element.

The following table lists the attributes of the relativeYearly element.

The reactiveRules Element

The reactiveRules element is a child of the top-level rules element. It contains one or more rule elements that define relative rules. Each rule element contains a when element and an optional actions element.

The actions element contains one or more scale elements that each has a unique target. The actions element can also contain custom elements that describe your own custom actions. See the topic "Extending and Modifying the Autoscaling Application Block" for more information.

The following snippet shows an example of a reactiveRules element. For more examples, see the topic "Defining Reactive Rules."

<reactiveRules>
  <rule name="Example Scaling Rule" rank="100">
    <when>
      <greater operand="CPU_RoleA" than="80"/>
    </when>
    <actions>
      <scale target="WorkerRoleA" by="2"/>
    </actions>
  </rule>
  ...
</reactiveRules>

Attributes of the rule Element

The following table describes the attributes of the rule element that defines a reactive rule. This rule element is a child of the reactiveRules element.

The when Element

The when element is a child of the rule element in a reactive rule. This element defines the Boolean expression that is evaluated to determine whether the rule's action should be executed. The when element contains one of the child elements in the following table.

The following table describes the attributes of the comparison****elements (greater, greaterOrEqual, less, lessOrEqual, equals) that make up the Boolean expression in the reactive rule. These elements are children of the when element or children of the and, any, or not elements.

The string value of each operand, than, and to attribute can be one of the following:

• The name of an operand defined in the operands element.
• An integer or decimal number.
• A simple expression that multiples a number and an operand.
• A simple expression that divides an operand by a number.

For complete examples of when elements, see the topic "Defining Reactive Rules."

The actions Element

The actions element is a child of the rule element in a reactive rule. This element defines the scaling actions that are performed when the expression in the when element evaluates to true. The actions element contains one or more scale elements or changeSetting attributes. It can also include custom elements that define custom scaling actions. See the topic "Extending and Modifying the Autoscaling Application Block" for more information.

The following table lists the attributes of the scale element.

The following table lists the attributes of the changeSetting element.

The block uses the changeSetting element to notify the Microsoft Azure application that it should perform a throttling action. See the topic "Implementing Throttling Behavior."

The operands Element

The operands element is a child of the top-level rules element. It contains zero or more child elements that define the operands to which the expressions in the reactive rules refer. The children of the operands element are some combination of either the performanceCounter element, the queueLength element, the roleInstanceCount element, or a custom element. See the topic "Extending and Modifying the Autoscaling Application Block" for more information about defining custom operands.

The following snippet shows an example of an operands element. For more examples, see the topic "Defining Reactive Rules."

<operands>
  <performanceCounter alias="CPU_45_RoleA" source="WorkerRoleA" 
    performanceCounterName="\Processor(_Total)\% Processor Time" 
    timespan="00:45:00" aggregate="Average"/>
  <performanceCounter alias="CPU_45_RoleBC" source="ScaleGroupB" 
    performanceCounterName="\Processor(_Total)\% Processor Time" 
    timespan="00:45:00" aggregate="Max"/>
  <queueLength alias="Length_10_QueueC" queue="QueueC"
    timespan="00:10:00" aggregate="Growth"/>
</operands>

The following table lists the attributes of the performanceCounter element.

The following table lists the attributes of the queueLength element.

The following table lists the attributes of the roleInstanceCount element.

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Last built: June 7, 2012