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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A component is made up of one or more OSGi bundles. A bundle is the modularization unit in OSGi, similar to a JAR file in Java. The component-based architecture of all WSO2 products gives developers flexibility to remove or add features with minimum dependencies.
The API Manager comprises the consists of the following high-level components:
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The main attributes of a method are described below:
| Attribute | Description |
|---|---|
| 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 ( 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:
| Header | Description | Sample values |
|---|---|---|
| Access-Control-Allow-Origin | Determines whether a resource can be shared with the resource of a given origin. The API Gateway validates the origin request header value against the list of origins defined under the Access Control Allow Origins configuration(this can be All Allow Origins or a specific value like localhost). If the host is in the allowed origin list, it will be set as the Access-Control-Allow-Origin response header in the response. | All Allow Origins(*), localhost |
| Access-Control-Allow-Headers | Determines, as part of the response to a preflight request (a request that checks to see if the CORS protocol is understood), which header field names can be used during the actual request. The gateway will set the header values defined under Access Control Allow Headers configurations. | authorization, Access-Control-Allow-Origin, Content-type, SOAPAction |
| Access-Control-Allow-Methods | This header specifies the method(s) allowed when accessing the resource in response to a preflight request. Required methods can be defined under the Access Control Allow Method configuration. | GET, PUT, POST, DELETE, PATCH, OPTIONS |
| Access-Control-Allow-Credentials | Determines whether or not the response to the request can be exposed to the page. It can be exposed when the header value is true. The header value can be set to true/false by enabling/disabling the Access Control Allow Credentials configuration. | true, false |
If you try to invoke an API with inline endpoints, you add the CORS Handler in the <handlers> section of the API's configuration as follows. Find the API's configuration in the <APIM_HOME>/repository/deployment/server/synapse-configs/default/api folder.Change your code according to the sample given here.
| 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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