Let's take a look at some concepts and terminology that you need to know in order to follow the use cases.
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API-level throttling
API-level throttling tiers are defined when managing APIs using the API Publisher portal. The UI looks as follows:
After API-level throttling tiers are set and the API is published, at subscription time, the consumers of the API can log in to the API Store and select which tier they are interested in as follows:
According to the tiers the subscriber selects, s/he is granted a maximum number of requests to the API. The default tiers are as follows:
- Bronze: 1 request per minute
- Silver: 5 requests per minute
- Gold: 20 requests per minute
- Unlimited: Allows unlimited access (you can disable the Unlimited tier by editing the
<TierManagement>node of the<APIM_HOME>/repository/conf/api-manager.xmlfile)
Setting tier permissions: Users with Manage Tiers permission can set role-based permissions to API-level access throttling tiers. This is done using the Tier Permissions menu in the API Publisher as shown below. For each tier, you can specify a comma-separated list of roles and either Allow or Deny access to the list.
A subscriber logged into the API Store can consume APIs using a specific tier only if s/he is assigned to a role that is allowed access. In the API Store, the subscriber sees a list of tiers that is filtered based on the subscriber's role. Only the ALLOWED roles appear here. By default, all tiers are allowed to everyone.
IP-level throttling
In IP-based throttling, you can limit the number of requests sent by a client IP (e.g., 10 calls from single client).
- Log in to the management console and click the Resources -> Browse menu.
Navigate to the
tiers.xmlfile in the registry location/_system/governance/apimgt/applicationdata.
Add your policy. For example, the throttling policy shown below allows only 1 API call per minute for a client from 10.1.1.1 and 2 calls per minute for a client from any other IP address.
Code Block language xml <wsp:Policy xmlns:wsp="http://schemas.xmlsoap.org/ws/2004/09/policy" xmlns:throttle="http://www.wso2.org/products/wso2commons/throttle"> <throttle:MediatorThrottleAssertion> <wsp:Policy> <throttle:ID throttle:type="IP">10.1.1.1</throttle:ID> <wsp:Policy> <throttle:Control> <wsp:Policy> <throttle:MaximumCount>1</throttle:MaximumCount> <throttle:UnitTime>60000</throttle:UnitTime> </wsp:Policy> </throttle:Control> </wsp:Policy> </wsp:Policy> <wsp:Policy> <throttle:ID throttle:type="IP">other</throttle:ID> <wsp:Policy> <throttle:Control> <wsp:Policy> <throttle:MaximumCount>2</throttle:MaximumCount> <throttle:UnitTime>60000</throttle:UnitTime> </wsp:Policy> </throttle:Control> </wsp:Policy> </wsp:Policy> </throttle:MediatorThrottleAssertion></wsp:Policy>Tip If you need to add a list of IPs / subnets for throttling you can derive the IP range from CIDR (Classless Inter-Domain Routing) notation and add it to the throttling policy configuration as follows.
Example :
If IP / subnet is "10.1.1.1/27" in CIDR notation, the IP address range is between "10.1.1.1 - 10.1.1.30" (if we keep 31 for broadcast). Therefore you can add throttling for the IP range as follows.
Code Block <throttle:ID throttle:type="IP">10.1.1.1 - 10.1.1.30</throttle:ID>
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API visibility and subscription
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When you add resources to an API, you define a URL pattern and HTTP methods. A resource can also have a list of OAuth scopes.
| URL Pattern | A URL pattern can be one of the following types:
The terms url-mapping and uri-template come from synapse configuration language. When an API is published in the API Publisher, a corresponding XML definition is created in the API Gateway. This XML file has a dedicated section for defining resources. See examples below:
url-mapping performs a one-to-one mapping with the request URL, whereas the uri-template performs a pattern matching. Parametrizing the URL allows the API Manager to map the incoming requests to the defined resource templates based on the message content and request URI. Once a uri-template is matched, the parameters in the template are populated appropriately. As per the above example, a request made to http://gatewa_host:gateway_port/api/v1/texas/houston sets the value of Also see http://tools.ietf.org/html/rfc6570 on URI templates. |
Once a request is accepted by a resource, it will be mediated through an in-sequence. Any response from the backend is handled through the out-sequence. Fault sequences are used to mediate errors that might occur in either sequence. The default in-sequence, out-sequence and fault sequences are generated when the API is published.
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The main attributes of a method are described below:
| OAuth scopes | You can define a list of OAuth scopes to an API's resource and assign one of them to each HTTP method. |
| Authentication type | The authentication type can be one of the following:
Note that for the resources that have HTTP verbs (GET, POST etc.) requiring authentication (i.e., Auth Type is not NONE), set None as the Auth type of OPTIONS. This is to support CORS (Cross Origin Resource Sharing) between the API Store and Gateway. (The above screenshot shows this). The auth type is cached in the API Manager for better performance. If you change the auth type through the UI, it takes about 15 minutes to refresh the cache. During that time, the server returns the old auth type from the cache. If you want the changes to be reflected immediately, please restart the server after changing the auth type. |
| Response content type | You can use this attribute to document in what type the backend sends the response back to the API Manager. Note that this attribute doesn't do any message type conversion, but used simply as a way of letting the user know what type the response will be. |
| Parameters | Parameters of an HTTP method are analogous to arguments of a function in an object-oriented programming language. A resource's parameters are cached in the resource cache at the API Gateway. |
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Cross-origin resource sharing
Cross-origin resource sharing (CORS) is a mechanism that allows restricted resources (e.g., fonts, JavaScript) of a Web page to be requested from another domain outside the domain from which the resource originated.
The Swagger API Console that is integrated in the API Manager runs as a JavaScript client in the API Store and makes calls from the Store to the API Gateway. Therefore, if you have the API Store and Gateway running on different ports, enable CORS between them.
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The elements are described below:
| XML Elements | Values | Description |
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| <Enabled> | True/False | Used to enable/disable sending CORS headers from the Gateway. By default, CORS is enabled (True). This is needed for Swagger to function properly. |
| <Access-Control-Allow-Origin> | HTTP and HTTPS Store Address. Change the Host and Port for correct values of your store. For example, https://localhost:9443,http://localhost:9763 | The value of the <Access-Control-Allow-Origin header>. Default values are API Store addresses that are required for swagger to function properly. |
| <Access-Control-Allow-Headers> | Header values you need to pass when invoking the API. For example, | Default values are sufficient for Swagger to function. |
Change your code according to the sample given here.
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| Code Block | ||
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<handlers> <handler class="org.wso2.carbon.apimgt.gateway.handlers.security.CORSRequestHandler"/> </handlers> |
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OAuth scopes
Scopes enable fine-grained access control to API resources based on user roles. You define scopes to an API's resources. When a user invokes the API, his/her OAuth 2 bearer token cannot grant access to any API resource beyond its associated scopes.
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You apply scopes to an API resource at the time the API is created or modified. In the API Publisher, click the API -> Add menu (to add a new API) or the Edit link next to an existing API. Then, navigate to the Manage tab and scroll down to see the Add Scopes button under Resources. A screen such as the following appears:
| Scope Key | A unique key for identifying the scope. Typically, it is prefixed by part of the API's name for uniqueness, but is not necessarily reader-friendly. |
| Scope Name | A human-readable name for the scope. It typically says what the scope does. |
| Roles | The user role(s) that are allowed to obtain a token against this scope. E.g., manager, employee. |
| Tip |
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Tip: When you generate access tokens to APIs protected by scope/s, a Select Scopes button is displayed in the My Subscriptions page for you to select the scope/s first and then generate the token to it.
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