Managing Throttling

By blacklisting requests, you can protect servers from common attacks and abuse by users. For example, if a malicious user misuses the system, all requests received from that particular user can be completely blocked. Tenant administrative users can block requests based on the following parameters:

• Block calls to specific APIs
• Block all calls from a given application
• Block requests coming from a specific IP address
• Block a specific user from accessing APIs

To blacklist a request, 

1. Log in to the Admin Portal using the URL https://localhost:9443/admin and your admin credentials.
2. Click Black List under the Throttle Policies section and click Add Item.
   
3. Select the item to black list, enter a value and click Blacklist.

Blacklisting PhoneVerification API

As described above you can blacklist requests for APIs, by Applications, to IP Addresses and for Users. Let's see how we can blacklist the requests come to the PhoneVerification API that we published in Quick Start Guide.

1. Log in to the Admin Portal using the URL https://localhost:9443/admin and your admin credentials.
2. Click Black List under the Throttle Policies section and click Add Item.
3. Select API Context and provide the Context of PhoneVerification API with version as the Value.
   
4. Click Blacklist.
5. Now login to API Store using the URL https://localhost:9443/store and invoke the API.
   You will see the following response.
   

Custom throttling

Custom throttling allows system administrators to define dynamic rules for specific use cases, which are applied globally across all tenants. When a custom throttling policy is created, it is possible to define any policy you like. The Traffic Manager acts as the global throttling engine and is based on the same technology as WSO2 Complex Event Processor (CEP), which uses the Siddhi query language. Users are therefore able to create their own custom throttling policies by writing custom Siddhi queries. The specific combination of attributes being checked in the policy need to be defined as the key (also called the key template). The key template usually includes a predefined format and a set of predefined parameters. It can contain a combination of allowed keys separated by a colon (:), where each key must start with the prefix $. The following keys can be used to create custom throttling policies:

resourceKey, userId, apiContext, apiVersion, appTenant, apiTenant, appId 

For example, the following sample custom policy allows the admin user to send 5 requests per minute to the Pizza Shack API. 

$userId:$apiContext:$apiVersion

FROM RequestStream
SELECT userId, ( userId == 'admin@carbon.super'  and apiContext == '/pizzashack/1.0.0' and apiVersion == '1.0.0') AS isEligible ,
str:concat('admin@carbon.super',':','/pizzashack/1.0.0:1.0.0') as throttleKey
  
INSERT INTO EligibilityStream;
FROM EligibilityStream[isEligible==true]#throttler:timeBatch(1 min) 
SELECT throttleKey, (count(userId) >= 5) as isThrottled, expiryTimeStamp group by throttleKey 
INSERT ALL EVENTS into ResultStream;

As shown in the above Siddhi query, the throttle key must match the key template format. If there is a mismatch between the key template format and the throttle key, requests will not be throttled.