Content-based Routing

Edit online

If you have a native API that is hosted at two or more endpoints, you can use the content-based routing protocol to route specific types of messages to specific endpoints. You can route messages to different endpoints based on specific values that appear in the request message. You might use this capability, for example, to determine which operation the consuming application has requested, and route requests for complex operations to an endpoint on a fast machine. For example, if your entry protocol is HTTP or HTTPS, you can select the Content-based routing. The requests are routed according to the content-based routing rules you create. You may specify how to authenticate requests.

Note: As the content-based routing policy's capabilities can also be configured using conditional routing policy, the content-based routing policy will be deprecated in future releases and the configurations will be migrated to conditional routing policy. Hence, IBM recommends to use conditional routing policy over content-based routing policy.

The table lists the properties that you can specify for this policy:

Property	Description
Default Route To: Specifies the URLs of two or more native services in a pool to which the requests are routed.
Endpoint URI	Specifies the URI of the native API endpoint to route the request to in case all routing rules evaluate to False. Service registries that have been added to the API Gateway instance are also included in the list. If you choose a service registry, API Gateway sends a request to the service registry to discover the IP address and port at which the native service is running. API Gateway replaces the service registry alias in the Endpoint URI with the IP address and port returned by the service registry. For example, if your service is hosted at the URL: `http://host:port/abc/`, you need to configure the Endpoint URI as: `http://${ServiceRegistryName}/abc/`. As this property supports variable framework, you can make use of the available variables. For example, you can configure the endpoint URI using hard coded URL, simple alias, endpoint alias, and variable syntax or any of these combination. If you define the endpoint URI as `http://${myAliasHost}:${request.headers.nativeport}/${sys:resource-path}`, where the `${myAliasHost}` variable syntax is used to define the simple alias and the `${request.headers.nativeport}` variable syntax is used to define the native port based on the request. For details about the variables available in webMethods API Gateway, see Variables Available in API Gateway. Note: If you use endpoint alias, make sure the endpoint alias is created before you define it in the policy. For example, if you define ${alias} syntax in the policy before creating the `alias` as endpoint alias, webMethods API Gateway considers ${alias} as custom variable or simple alias and tries to resolve against those. So in that case, after creating endpoint alias you have to edit and save the API or policy to associate ${alias} syntax with the endpoint alias.
HTTP Method	This is applicable for REST-based APIs. Specifies the available routing methods: GET, POST, PUT, DELETE, and CUSTOM (default). When CUSTOM is selected, the HTTP method in the incoming request is sent to the native service. When other methods are selected, the selected method is used in the request sent to the native service. Note: IBM recommends to use Request Transformation > Method Transformation to achieve this as other transformations can also be done under the same policy.
SOAP Optimization Method	This is applicable for SOAP-based APIs. Specifies the optimization methods that webMethods API Gateway can use to parse SOAP requests to the native API. Select one of the following options: MTOM. webMethods API Gateway uses the Message Transmission Optimization Mechanism (MTOM) to parse SOAP requests to the API. SwA. webMethods API Gateway uses the SOAP with Attachment (SwA) technique to parse SOAP requests to the API. None. webMethods API Gateway does not use any optimization method to parse the SOAP requests to the API. This is selected by default.
HTTP Connection Timeout (seconds)	Specifies the time interval (in seconds) after which a connection attempt times out. The precedence of the Connection Timeout configuration is as follows: If you specify a value for the Connection timeout field in routing endpoint alias, then the Connection timeout value specified in the Endpoint alias section takes precedence over the timeout values defined at the API level and the global level. If you specify a value 0 for the Connection timeout field in routing endpoint alias, then webMethods API Gateway uses the value specified in the Connection timeout field in the routing protocol processing step of an API. The Read Timeout value specified at an API level takes precedence over the global configuration. If you specify a value 0 or do not specify a value for the Connection timeout field in the routing protocol processing step at the API level or specify a value 0 at an alias level, then webMethods API Gateway uses the value specified in this pg.endpoint.connectionTimeout property. If you do not specify any value for pg.endpoint.connectionTimeout, then webMethods API Gateway uses the default value of 30 seconds.
Read Timeout (seconds)	Specifies the time interval (in seconds) after which a socket read attempt times out. The precedence of the Read Timeout configuration is as follows: If you specify a value for the Read timeout field in routing endpoint alias, then the Read timeout value specified in the Endpoint alias section takes precedence over the timeout values defined at the API level and the global level. If you specify a value 0 for the Read timeout field in routing endpoint alias, then webMethods API Gateway uses the value specified in the Read Timeout field in the routing protocol processing step of an API. The Read Timeout value specified at an API level takes precedence over the global configuration. If you specify a value 0 or do not specify a value for the Read timeout field in the routing protocol processing step at the API level or specify a value 0 at an alias level, then webMethods API Gateway uses the value specified in this pg.endpoint.readTimeout property. If you do not specify any value for pg.endpoint.readTimeout, then webMethods API Gateway uses the default value of 30 seconds.
Pass WS-Security Headers	This is applicable for SOAP-based APIs. Selecting this indicates that webMethods API Gateway should pass the WS-Security headers of the incoming requests to the native API.
SSL Configuration. Configures keystore, key alias, and truststore for securing connections to native APIs.
Keystore Alias	Specifies the keystore alias configured in webMethods API Gateway. This value (along with the value of Client Certificate Alias) is used for performing SSL client authentication. Lists all available keystores. If you have not configured any keystore, the list is empty.
Key Alias	Specifies the alias for the private key, which must be stored in the keystore specified by the keystore alias.
Truststore Alias	Specifies the alias for the truststore that contains the list of CA certificates that API Gateway uses to validate the trust relationship with the native API. If you do not configure any truststore alias, it implies that webMethods API Gateway does not validate the certificates provided by native APIs.
Service Registry Configuration
Service Discovery Endpoint Parameter	Values required for constructing the discovery service URI. Parameter: An alias that you have included in the discovery service URI while adding the service registry to API Gateway. Value: Specifies a value for the path parameter. The alias specified in Path Parameter is substituted with this value when invoking the discovery service. For example: if the service registry configuration of the service registry that you have selected in Endpoint URI has Service discovery path set to `/catalog/service/{serviceName}` (and the `{serviceName}` alias is intended for passing the service name), you must enter `{serviceName}` as Parameter and the name of the service as Value. As the Value field supports variable framework, you can make use of the available variables as path parameters. For example, if you provide a parameter as `{serviceName}`( in Service discovery path while you define a service registry) and the corresponding values for the path parameter as `${request.header.var1}`, the value in `var1` retrieved from the request header substitutes the service name. For details about the variables available in webMethods API Gateway, see Variables Available in API Gateway.
Rule: Defines the routing decisions based on one of the following routing options. Click Add Rule and provide the following information.
Payload Identifier	Specifies using the payload identifier to identify the client, extract the custom authentication credentials supplied in the request represented using the payload identifier, and verify the client's identity. In the Payload identifier section, click Add payload identifier, provide the following information, and click Add. Expression type. Specifies the type of expression, which is used for identification. You can select one the following expression type: XPath. Provide the following information: Payload Expression. Specifies the payload expression that the specified XPath expression type in the request has to be converted to. For example: /name/id Namespace Prefix. The namespace prefix of the payload expression to be validated. Namespace URI. The namespace URI of the payload expression to be validated. Note: You can add multiple namespace prefix and URI by clicking . JSONPath. Provide the Payload Expression that specifies the payload expression that the specified JSONPath expression type in the request has to be converted to. For example: $.name.id Text. Provide the Payload Expression that specifies the payload expression that the specified Text expression type in the request has to be converted to. For example: any valid regular expression. You can add multiple payload identifiers as required. Note: Only one payload identifier of each type is allowed. For example, you can add a maximum of three payload identifiers, each being of a different type.
Route To. Specifies the Endpoint URI of native APIs in a pool to which the requests are routed.
Endpoint URI	Specifies the URI of the native API endpoint to route the request to. You can use service registries in a similar manner as described in the main Endpoint URI above. For example, if your service is hosted at the URL: `http://host:port/abc/`, you need to configure the Endpoint URI as: `http://${ServiceRegistryName}/abc/`. As this property supports variable framework, you can make use of the available variables. For example, you can configure the endpoint URI using hard coded URL, simple alias, endpoint alias, and variable syntax or any of these combination. If you define the endpoint URI as `http://${myAliasHost}:${request.headers.nativeport}/${sys:resource-path}`, where the `${myAliasHost}` variable syntax is used to define the simple alias and the `${request.headers.nativeport}` variable syntax is used to define the native port based on the request. For details about the variables available in webMethods API Gateway, see Variables Available in API Gateway. Note: If you use endpoint alias, make sure the endpoint alias is created before you define it in the policy. For example, if you define ${alias} syntax in the policy before creating the `alias` as endpoint alias, webMethods API Gateway considers ${alias} as custom variable or simple alias and tries to resolve against those. So in that case, after creating endpoint alias you have to edit and save the API or policy to associate ${alias} syntax with the endpoint alias.
HTTP Method	This is applicable for REST-based APIs. Specifies the available routing methods: GET, POST, PUT, DELETE, and CUSTOM (default). When CUSTOM is selected, the HTTP method in the incoming request is sent to the native service. When other methods are selected, the selected method is used in the request sent to the native service.
Soap Optimization Method	This is applicable for SOAP-based APIs. Specifies the optimization methods that webMethods API Gateway can use to parse SOAP requests to the native API. Select one of the following options: MTOM. webMethods API Gateway uses the Message Transmission Optimization Mechanism (MTOM) to parse SOAP requests to the API. SwA. webMethods API Gateway uses the SOAP with Attachment (SwA) technique to parse SOAP requests to the API. None. webMethods API Gateway does not use any optimization method to parse the SOAP requests to the API. This is selected by default.
HTTP Connection Timeout (seconds)	Specifies the time interval (in seconds) after which a connection attempt times out. The precedence of the Connection Timeout configuration is as follows: If you specify a value for the Connection timeout field in routing endpoint alias, then the Connection timeout value specified in the Endpoint alias section takes precedence over the timeout values defined at the API level and the global level. If you specify a value 0 for the Connection timeout field in routing endpoint alias, then webMethods API Gateway uses the value specified in the Connection timeout field in the routing protocol processing step of an API. The Read Timeout value specified at an API level takes precedence over the global configuration. If you specify a value 0 or do not specify a value for the Connection timeout field in the routing protocol processing step at the API level or specify a value 0 at an alias level, then webMethods API Gateway uses the value specified in this pg.endpoint.connectionTimeout property. If you do not specify any value for pg.endpoint.connectionTimeout, then webMethods API Gateway uses the default value of 30 seconds.
Read Timeout (seconds)	Specifies the time interval (in seconds) after which a socket read attempt times out. The precedence of the Read Timeout configuration is as follows: If you specify a value for the Read timeout field in routing endpoint alias, then the Read timeout value specified in the Endpoint alias section takes precedence over the timeout values defined at the API level and the global level. If you specify a value 0 for the Read timeout field in routing endpoint alias, then webMethods API Gateway uses the value specified in the Read Timeout field in the routing protocol processing step of an API. The Read Timeout value specified at an API level takes precedence over the global configuration. If you specify a value 0 or do not specify a value for the Read timeout field in the routing protocol processing step at the API level or specify a value 0 at an alias level, then webMethods API Gateway uses the value specified in this pg.endpoint.readTimeout property. If you do not specify any value for pg.endpoint.readTimeout, then webMethods API Gateway uses the default value of 30 seconds.
Pass WS-Security Headers	This is applicable for SOAP-based APIs. Selecting this indicates that webMethods API Gateway should pass the WS-Security headers of the incoming requests to the native API.
SSL Configuration	Configures keystore, key alias, and truststore for securing connections to native APIs. Provide the following information: Keystore Alias. Specifies the keystore alias configured in webMethods API Gateway. This value (along with the value of Client Certificate Alias) is used for performing SSL client authentication. Lists all available keystores. If you have not configured any keystore, the list is empty. Key Alias. Specifies the alias for the private key, which must be stored in the keystore specified by the keystore alias. Truststore Alias. Specifies the alias for the truststore that contains the list of CA certificates that API Gateway uses to validate the trust relationship with the native API. If you do not configure any truststore alias, it implies that webMethods API Gateway does not validate the certificates provided by native APIs.
Service Registry Configuration
Service Discovery Endpoint Parameter	Values required for constructing the discovery service URI. Parameter: An alias that you have included in the discovery service URI while adding the service registry to API Gateway. Value: Specifies a value for the path parameter. The alias specified in Path Parameter is substituted with this value when invoking the discovery service. For example: if the service registry configuration of the service registry that you have selected in Endpoint URI has Service discovery path set to `/catalog/service/{serviceName}` (and the `{serviceName}` alias is intended for passing the service name), you must enter `{serviceName}` as Parameter and the name of the service as Value. As the Value field supports variable framework, you can make use of the available variables as path parameters. For example, if you provide a parameter as `{serviceName}`( in Service discovery path while you define a service register) and the corresponding values for the path parameter as `${request.header.var1}`, the value in var 1 retrieved from the request header will substitute the service name. For details about the variables available in webMethods API Gateway, see Variables Available in API Gateway.