Criteria

Rules are more powerful when they respond to different criteria set for the client requests. To do so, the rule needs to specify children containing an array of nested rule objects. Along with a descriptive name, child rules may contain an additional set of criteria objects that determine when its behaviors execute.

In this example, the child rule's contentType criteria matches requests for common HTML, CSS, and JavaScript files, and applies the gzipResponse behavior to compress them.

{
    "rules": {
        "name": "default",
        "options": {
            "is_secure": false
        },
        "behaviors": [
            {
                "name": "origin",
                "options": {
                    "originType": "CUSTOMER",
                    "hostname": "example.com",
                    "forwardHostHeader": "REQUEST_HOST_HEADER",
                    "cacheKeyHostname": "ORIGIN_HOSTNAME",
                    "compress": true,
                    "tcipEnabled": false,
                    "httpPort": 80
                }
            },
            {
                "name": "cpCode",
                "options": {
                    "value": {
                        "id": 12345,
                        "name": "main site"
                    }
                }
            }
        ],
        "children": [
            {
                "name": "Compress Text Content",
                "criteria": [
                    {
                        "name": "contentType",
                        "options": {
                            "matchOperator": "IS_ONE_OF",
                            "matchWildcard": true,
                            "matchCaseSensitive": false,
                            "values": [
                                "text/html*",
                                "text/css*",
                                "application/x-javascript*"
                            ]
                        }
                    }
                ],
                "behaviors": [
                    {
                        "name": "gzipResponse",
                        "options": { "behavior": "ALWAYS" }
                    }
                ]
            }
        ]
    }
}

Criteria are structured exactly the same as behavior objects, with a name string identifier and a nested options object. Most criteria options behave similarly. The values option usually specifies the set of strings you're trying to match. Throughout PAPI, whenever a value is optionally plural, it's always represented as an array. The matchWildcard options allow you to match flexibly with * and ? characters, and various matchCaseSensitive options allow you to ignore case. The matchOperator option typically inverts the result, so that the criteria succeeds if specified values don't match.

The example above features a single contentType criteria. Once you define more than one, the rule needs a criteriaMustSatisfy field to set whether to match any or all criteria. This alternate example of the children array adds a random criteria to match half the requests for the specified contentType.

"children": [
    {
        "name": "Compress Half of Requests for Text Content",
        "criteriaMustSatisfy": "all",
        "criteria": [
            {
                "name": "contentType",
                "options": {
                    "matchOperator": "IS_ONE_OF",
                    "matchWildcard": true,
                    "matchCaseSensitive": false,
                    "values": [
                        "text/html*",
                        "text/css*",
                        "application/x-javascript*"
                    ]
                }
            },
            {
                "name": "random",
                "options": { "bucket": 50 }
            }
        ],
        "behaviors": [
            {
                "name": "gzipResponse",
                "options": { "behavior": "ALWAYS" }
            }
        ]
    }
]

In this example, criteriaMustSatisfy is set to all. If it were set to any, the criteria would compress all text content, and half of all other content, including images that are already compressed. This is almost certainly not what you want, and exemplifies the sort of problem that falls beyond what the API can identify for you, as discussed in the Errors section.

Note that rules don't provide any explicit support for else cases in response to criteria matches, but there are a couple of ways to implement them:

• Specify exclusive pairs of match criteria. From the example above, the first rule could specify a contentType criteria that matches HTML/CSS/JavaScript using a matchOperator of IS_ONE_OF. The second rule could specify the same contentType criteria, only with a matchOperator of IS_NOT_ONE_OF.

• Override a parent rule's behavior. In the random example above, if you were to apply some other behavior to the remaining half of the requests, you'd need to do so as part of the parent rule. If the parent rule enables a behavior that shouldn't apply to the child, the child rule needs to specify the behavior again specifically to disable it.