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The throttle mechanism is used to control access to the services at different levels. WSO2 ESB provides an effective and efficient way to apply the throttle mechanism to your Web services.

Levels of

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throttling

You can enable throttling at the following levels in WSO2 ESB:

Global level - If it is enabled globally, restrictions are applied globally (for every message coming into the server).
Service level - If it is enabled for a particular service, restrictions are applied to all the messages coming into that service.

Adding Throttling to a Service

Use this function to add a throttle parameter that specifies a variable millisecond wait between calls or a variable maximum number of calls per unit of time. This would facilitate the smooth operation of Web services and REST using the Web service and HTTP client steps.

Info

title	Tip

The throttling option is disabled by default. If you want to add the throttling mechanism, you should enable it.

Follow the instructions below to add throttling to a service.

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Click on the relevant tab for instructions to add a throttling policy at the required level.

Localtabgroup

Localtab

title	Global level

Follow the instructions below to define a throttle policy at a global level.

Enter your user name and password to log on to the ESB Management Console.
Go to the Main tab. In the Modules section, click List to open the Deployed Modules page.
In the row that displays wso2throttle module, click Configure to open the Global Throttling Configuration page.
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In the Enable Throttling parameter, select Yes. The existing throttle configuration will appear in the wizard as shown in the example below.

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Configure the following parameters as required to update the throttle policy.

Parameter Name Description

Maximum Concurrent Accesses The maximum number of requests served concurrently by the service at any given time.

Range

The range of IP addresses or the domain (based on the value selected for the Type parameter) to be restricted from accessing the service. Requests from these IP addresses/domains will be restricted based on the specified values.

Type

This specifies the basis on which the clients should be restricted from accessing the proxy service. Possible values are as follows.

IP: This restricts access to the service based on the IP address of the client. If you select this, enter the relevant range ofIP addresses in the Range parameter (e.g., 10.100.1.30-10.100.1.60).
Domain: This restricts access to the service based on the domain of the client. If you select this, enter the relevant domain in the Range parameter (e.g., *.wso2.com).

Info

It is recommended to use IP based throttling instead of domain based throttling since the performance overhead is minimal when IP based throttling is used.

Since the use of domain based throttling results in a high performance overhead, it is not provided by default with the ESB distribution. However, it can be provided as a patch if you need to use domain based throttling.

Max Request Count
Anchor
MRC
MRC

This parameter specifies the maximum number of requests that should be handled within the time interval specified in the Unit Time parameter.

Tip
This parameter is applicable only when the value selected for the Access parameter is `Control`.

Unit Time (ms)
Anchor
UT
UT

The time interval for which the maximum number of requests specified for the Throttle ID in the Max Request Count parameter apply.

Tip
This parameter is applicable only when the value selected for the Access parameter is `Control`.

Prohibit Time Period (ms)
Anchor
PTP
PTP

If the number of requests entered in the Max Request Count parameter is achieved before the time interval entered in the Unit Time (ms) parameter has elapsed, no more requests are taken by the inflow throttle handler for the time period entered in this parameter. Entering a value in this parameter alters the unit time.

For example:

Max Request Count = 50
Unit Time = 50000 ms
Prohibit Time Period = 5000 ms

If 50 requests are received within 35000 milliseconds, no requests will be taken for the next 5000 milliseconds. Thus, the time slot considered as the unit time is changed to 40000 milliseconds. If no value is entered in the Prohibit Time Period (ms) parameter, no requests will be taken until 15000 more milliseconds (i.e. the remainder of the unit time) have elapsed.

Tip
This parameter is applicable only when the value selected for the Access parameter is `Control`.

Access

This parameter is used to specify he extent to which the IP addresses/domains specified in the Range parameter are allowed access to the service to which the throttle policy is applied. Possible values are as follows.

Allow: If this is selected, the specified IP addresses/domains are allowed to access the services to which the throttle ID is applied without any restrictions.
Deny: If this is selected, specified IP addresses/domains are not allowed to access the services to which the throttle ID is applied.
Control: If this is selected, the specified IP addresses/domains are allowed to access the services to which the throttle ID is applied. However, the number of times they can access the services is controlled by the Max Request Count , Unit Time (ms) ,and the Prohibit Time Period (ms) parameters.

Actions Click Delete in the relevant row to delete an entry.

Click Finish to save the information.

Localtab

title	Service level

Anchor

	service
	service

Info
This section explains how to add a throttle policy to a service carry out throttling before mediation is carried out on the requests. If you want the throttling to be carried out after the requests have reached the mediation layer, you can add the Throttle mediator to the proxy configuration.

Follow the instructions below to define a throttle policy for a service.

Enter your user name and password to log on to the ESB Management Console.
Click the Main

...

tab. Under Web Services, click List

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to open the Deployed Services

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page.
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Click on the service for which you want to enable throttling to open its Service Dashboard.
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In the Quality of Service Configuration panel, click Access Throttling. The Throttling Configuration

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page for the service will appear.
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In the Enable Throttling

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parameter, select Yes. The existing throttle configuration will appear in the wizard as shown in the example below.
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Configure the following parameters as required to update the throttle policy.

Parameter Name	Description
Maximum Concurrent Accesses	The maximum number of requests served concurrently by the service at any given time.
Range	The range of IP addresses or the domain (based on the value selected for the Type parameter) to be restricted from accessing the service. Requests from these IP addresses/domains will be restricted based on the specified values.
Type	This specifies the basis on which the clients should be restricted from accessing the proxy service. Possible values are as follows. IP: This restricts access to the service based on the IP address of the client. If you select this, enter the relevant range ofIP addresses in the Range parameter (e.g., `10.100.1.30-10.100.1.60`). Domain: This restricts access to the service based on the domain of the client. If you select this, enter the relevant domain in the Range parameter (

...

e.g., *.wso2.com).

Info

It is recommended to use IP based throttling instead of domain based throttling since the performance overhead is minimal when IP based throttling is used.

Since the use of domain based throttling results in a high performance overhead, it is not provided by default with the ESB distribution. However, it can be provided as a patch if you need to use domain based throttling.

Max Request Count
Anchor
MRC
MRC

This parameter specifies the maximum number of requests that should be handled within the time interval specified in the Unit Time parameter.

Tip
This parameter is applicable only when the value selected for the Access parameter is `Control`.

Unit Time (ms)
Anchor
UT
UT

The time interval for which the maximum number of requests specified for the Throttle ID in the Max Request Count parameter apply.

Tip
This parameter is applicable only when the value selected for the Access parameter is `Control`.

Prohibit Time Period (ms)
Anchor
PTP
PTP

If the number of requests entered in the Max Request Count parameter is achieved before the time interval entered in the Unit Time (ms) parameter has elapsed, no more requests are taken by the inflow throttle handler for the time period entered in this parameter. Entering a value in this parameter alters the unit time.

For example:

Max Request Count = 50
Unit Time = 50000 ms
Prohibit Time Period = 5000 ms

If 50 requests are received within 35000 milliseconds, no requests will be taken for the next 5000 milliseconds. Thus, the time slot considered as the unit time is changed to 40000 milliseconds. If no value is entered in the Prohibit Time Period (ms) parameter, no requests will be taken until 15000 more milliseconds (i.e. the remainder of the unit time) have elapsed.

Tip
This parameter is applicable only when the value selected for the Access parameter is `Control`.

Access

This parameter is used to specify he extent to which the IP addresses/domains specified in the Range parameter are allowed access to the service to which the throttle policy is applied. Possible values are as follows.

Allow: If this is selected, the specified IP addresses/domains are allowed to access the services to which the throttle ID is applied without any restrictions.
Deny: If this is selected, specified IP addresses/domains are not allowed to access the services to which the throttle ID is applied.
Control: If this is selected, the specified IP addresses/domains are allowed to access the services to which the throttle ID is applied. However, the number of times they can access the services is controlled by the Max Request Count , Unit Time (ms) ,and the Prohibit Time Period (ms) parameters.

Actions Click Delete in the relevant row to delete an entry.

You can create as many entries as required by clicking Add New Entry.

Click

...

Finish to save the information.

Info

You can also specify the throttle policy within a proxy service configuration as a key by saving the policy in the registry or by saving it as a local entry. However, when you are not using the Management Console, you are required to manually create an entry in the <ESB_HOME/repository/deployment/server/servicemetafiles/<Service_Name>.xml file to enable throttling as shown in the example below.

Code Block

language	xml

<?xml version="1.0" encoding="UTF-8"?>
<serviceGroup name="ThrottleProxy" successfullyAdded="true">
   <service name="ThrottleProxy"
            exposedAllTransports="false"
            serviceDeployedTime="1431430083400"
            successfullyAdded="true">
      <operation name="mediate">
         <module name="addressing" version="4.2.0" type="engagedModules"/>
         <module name="POXSecurityModule" version="4.2.2" type="engagedModules"/>
         <module name="wso2statistics" version="4.2.2" type="engagedModules"/>
         <module name="ServerAdminModule" version="4.2.0" type="engagedModules"/>
         <module name="pagination" version="4.2.0" type="engagedModules"/>
      </operation>
      <bindings>
         <binding name="ThrottleProxySoap12Binding">
            <operation name="mediate"/>
            <operation name="GetMetadata"/>
         </binding>
         <binding name="ThrottleProxySoap11Binding">
            <operation name="mediate"/>
            <operation name="GetMetadata"/>
         </binding>
         <binding name="ThrottleProxyHttpBinding">
            <operation name="mediate"/>
            <operation name="GetMetadata"/>
         </binding>
      </bindings>
      <policies>
         <policy policyType="3">
            <policyUUID>WSO2ServiceThrottlingPolicy</policyUUID>
            <wsp:Policy xmlns:wsp="http://schemas.xmlsoap.org/ws/2004/09/policy"
                        xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd"
                        wsu:Id="WSO2ServiceThrottlingPolicy">
               <throttle:ServiceThrottleAssertion xmlns:throttle="http://www.wso2.org/products/wso2commons/throttle">
                  <wsp:Policy>
                     <throttle:ID throttle:type="IP">10.100.0.37</throttle:ID>
                     <wsp:Policy>
                        <throttle:Control>
                           <wsp:Policy>
                              <throttle:MaximumCount>5</throttle:MaximumCount>
                              <throttle:UnitTime>100000</throttle:UnitTime>
                              <throttle:ProhibitTimePeriod wsp:Optional="true">10000</throttle:ProhibitTimePeriod>
                           </wsp:Policy>
                        </throttle:Control>
                     </wsp:Policy>
                  </wsp:Policy>
                  <wsp:Policy>
                     <throttle:ID throttle:type="DOMAIN">localhost</throttle:ID>
                     <wsp:Policy>
                        <throttle:Control>
                           <wsp:Policy>
                              <throttle:MaximumCount>1</throttle:MaximumCount>
                              <throttle:UnitTime>10000</throttle:UnitTime>
                              <throttle:ProhibitTimePeriod wsp:Optional="true">10000</throttle:ProhibitTimePeriod>
                           </wsp:Policy>
                        </throttle:Control>
                     </wsp:Policy>
                  </wsp:Policy>
                  <wsp:Policy>
                     <throttle:ID throttle:type="IP">127.0.0.1</throttle:ID>
                     <wsp:Policy>
                        <throttle:Control>
                           <wsp:Policy>
                              <throttle:MaximumCount>1</throttle:MaximumCount>
                              <throttle:UnitTime>100000</throttle:UnitTime>
                              <throttle:ProhibitTimePeriod wsp:Optional="true">10000</throttle:ProhibitTimePeriod>
                           </wsp:Policy>
                        </throttle:Control>
                     </wsp:Policy>
                  </wsp:Policy>
               </throttle:ServiceThrottleAssertion>
            </wsp:Policy>
         </policy>
      </policies>
      <module name="addressing" version="4.2.0" type="engagedModules"/>
      <module name="POXSecurityModule" version="4.2.2" type="engagedModules"/>
      <module name="wso2statistics" version="4.2.2" type="engagedModules"/>
      <module name="ServerAdminModule" version="4.2.0" type="engagedModules"/>
      <module name="pagination" version="4.2.0" type="engagedModules"/>
      <parameter name="serviceType" type="1">proxy</parameter>
      <policyUUID>WSO2ServiceThrottlingPolicy</policyUUID>
      <parameter name="disableREST" type="1">true</parameter>
      <module name="wso2throttle" version="4.2.0" type="engagedModules"/>
      <association destinationPath="/repository/transports/https/listener"
                   type="exposedTransports"/>
      <association destinationPath="/repository/transports/http/listener"
                   type="exposedTransports"/>
   </service>
</serviceGroup>

The proxy service configuration in this example can be as follows.

Code Block

language	xml

<?xml version="1.0" encoding="UTF-8"?>
<proxy xmlns="http://ws.apache.org/ns/synapse"
       name="ThrottleProxy"
       transports="https http"
       startOnLoad="true"
       trace="disable">
   <description/>
   <target>
      <endpoint>
         <address uri="http://localhost:9000/services/SimpleStockQuoteService"/>
      </endpoint>
      <inSequence>
         <log level="full"/>
      </inSequence>
   </target>
  <policy key="throttlePolicy1"/>
</proxy>

The following is an example of a throttle policy configuration that can be saved in the registry or as a local entry.

Note
You need to use the same string (e.g., `throttlePolicy1`) for the throttle policy key of both the proxy service configuration, and the local entry definition, which is saved in the registry.

Code Block

language	xml

<?xml version="1.0" encoding="UTF-8"?>
<localEntry xmlns="http://ws.apache.org/ns/synapse" key="throttlePolicy1">
   <wsp:Policy xmlns:wsp="http://schemas.xmlsoap.org/ws/2004/09/policy"
               xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd"
               wsu:Id="WSO2ServiceThrottlingPolicy">
      <throttle:ServiceThrottleAssertion xmlns:throttle="http://www.wso2.org/products/wso2commons/throttle">
         <wsp:Policy>
            <throttle:ID throttle:type="IP">10.100.0.37</throttle:ID>
            <wsp:Policy>
               <throttle:Control>
                  <wsp:Policy>
                     <throttle:MaximumCount>5</throttle:MaximumCount>
                     <throttle:UnitTime>100000</throttle:UnitTime>
                     <throttle:ProhibitTimePeriod wsp:Optional="true">10000</throttle:ProhibitTimePeriod>
                  </wsp:Policy>
               </throttle:Control>
            </wsp:Policy>
         </wsp:Policy>
         <wsp:Policy>
            <throttle:ID throttle:type="DOMAIN">localhost</throttle:ID>
            <wsp:Policy>
               <throttle:Control>
                  <wsp:Policy>
                     <throttle:MaximumCount>5</throttle:MaximumCount>
                     <throttle:UnitTime>100000</throttle:UnitTime>
                     <throttle:ProhibitTimePeriod wsp:Optional="true">10000</throttle:ProhibitTimePeriod>
                  </wsp:Policy>
               </throttle:Control>
            </wsp:Policy>
         </wsp:Policy>
         <wsp:Policy>
            <throttle:ID throttle:type="IP">127.0.0.1</throttle:ID>
            <wsp:Policy>
               <throttle:Control>
                  <wsp:Policy>
                     <throttle:MaximumCount>5</throttle:MaximumCount>
                     <throttle:UnitTime>100000</throttle:UnitTime>
                     <throttle:ProhibitTimePeriod wsp:Optional="true">10000</throttle:ProhibitTimePeriod>
                  </wsp:Policy>
               </throttle:Control>
            </wsp:Policy>
         </wsp:Policy>
      </throttle:ServiceThrottleAssertion>
   </wsp:Policy>
   <description/>
</localEntry>

Versions Compared

Old Version 13

New Version Current

Key

Levels of

throttling

Adding Throttling to a Service