Differentiated service identifies traffic as classes. The most common classes are defined using client IP addresses, application ports, server types, protocols, local IP addresses, and schedules. All traffic that conforms to the same class is treated equally.
For more advanced classification, you can specify server data to set different levels of service for some of your iSeries applications. Using server data is optional, but might be helpful when you want to classify at a lower level. Server data is based on two types of application data: application token or Uniform Resource Identifier (URI). If traffic matches the token or URI you specify in the policy, the policy will be applied to the outbound response, thus giving the outbound traffic, whatever priority is specified in the differentiated service policy.
Using application data tells the policy to respond to specific parameters (token and priority) passed by the application to the server through the sendmsg() application programming interface (API). This setting is optional. If you do not need this level of granularity in your outbound policies, select All tokens in the wizard. You can match an application's token and priority with a specific token and priority set in the outbound policy, if you want to. In the policy, there are two parts to setting the application data, which include the token and the priority.
An application token is any character string that can represent a defined resource, such as myFTP. The token you specify in the quality of service (QoS) policy is matched against the token provided by the outbound application. The application provides the token value through the sendmsg() API. If the tokens match, the application traffic is included in the differentiated service policy.
To use an application token in a differentiated service policy, follow these steps:
The application priority you specify is matched against the application priority provided by the outbound application. The application provides the priority value using the sendmsg() API. If the priorities match, the application traffic is included in the differentiated service policy. All traffic defined in the differentiated service policy will still receive the priority given to the entire policy.
When you specify application token as the application data type, the application providing this information to the server must be specifically coded to use the sendmsg() API. This is done by the application programmer. The application's documentation should provide valid values (token and priority), which the QoS administrator will use in the differentiated service policy. The differentiated service policy then applies its own priority and classification to traffic that matches the token set in the policy. If the application does not have values that match the values set in the policy, you must either update the application or use different application data parameters for the differentiated service policy.
When creating a differentiated service policy, the wizard allows you to set server data information, as discussed in "Use application token with differentiated service policies" section. Although the fields in the wizard prompt you for an application token, you can instead specify a relative URI. Again, this is optional. If you do not need this level of granularity in your outbound policies, select All tokens in the wizard. You can match a specific URI set in the outbound policy if you want to.
The relative URI is actually a subset of an absolute URI (similar to the old absolute URL). Consider this example: http://www.ibm.com/software. The http://www.ibm.com/software segment is considered the absolute URI. The /software segment is the relative URI. All relative URI values must begin with one forward slash (/). The following segments are valid relative URI examples:
Before you set up a differentiated service policy that uses URLs, you must ensure that the application port assigned for the URI matches the Listen directive enabled for the Fast Response Cache Accelerator (FRCA) in the Apache Web Server configuration. To change or view the port for your HTTP server, see Manage addresses and ports for your HTTP server (powered by Apache).
FRCA identifies the URI for each outbound HTTP response. It compares the URI related to the outbound response to the URI defined in each differentiated service policy. The first policy with a token string (URI) that best matches the URI identified by FRCA, is applied to all responses for the URI.