String value matching

You can filter messages by matching string values to message attribute values, or to message body property values. String values are enclosed in double quotation marks in the JSON policy.

You can use the following string operations to match message attributes or message body.

Exact matching

Exact matching occurs when a policy property value matches one or more message attribute values.

Consider the following policy property:

"customer_interests": ["rugby", "tennis"]

It matches the following message attributes:

"customer_interests": {"Type": "String", "Value": "rugby"}

"customer_interests": {"Type": "String", "Value": "tennis"}

It also matches the following message bodies:

{
   "customer_interests": "rugby"
}

{
   "customer_interests": "tennis"
}

However, it doesn't match the following message attribute:

"customer_interests": {"Type": "String", "Value": "baseball"}

Nor does it match the following message body:

{
   "customer_interests": "baseball"
}

Prefix matching

When a policy property includes the keyword prefix, it matches any message attribute or body property values that begin with the specified characters.

Consider the following policy property:

"customer_interests": [{"prefix": "bas"}]

It matches either of the following message attributes:

"customer_interests": {"Type": "String", "Value": "baseball"}

"customer_interests": {"Type": "String", "Value": "basketball"}

It also matches either of the following message bodies:

{
   "customer_interests": "baseball"
}

{
   "customer_interests": "basketball"
}

However, it doesn't match the following message attribute:

"customer_interests": {"Type": "String", "Value": "rugby"}

Nor does it match the following message body:

{
   "customer_interests": "rugby"
}

Anything-but matching

When a policy property value includes the keyword anything-but, it matches any message attribute or message body values that don't include any of the policy property values. anything-but can be combined with "exists": false.

Consider the following policy property:

"customer_interests": [{"anything-but": ["rugby", "tennis"]}]

It matches either of the following message attributes:

"customer_interests": {"Type": "String", "Value": "baseball"}

"customer_interests": {"Type": "String", "Value": "football"}

It also matches either of the following message bodies:

{
   "customer_interests": "baseball"
}

{
   "customer_interests": "football"
}

Moreover, it matches the following message attribute (because it contains a value that isn't rugby or tennis):

"customer_interests": {"Type": "String.Array", "Value": "[\"rugby\", \"baseball\"]"}

And it also matches the following message body (because it contains a value that isn't rugby or tennis):

{
   "customer_interests": ["rugby", "baseball"]
}

However, it doesn't match the following message attribute:

"customer_interests": {"Type": "String", "Value": "rugby"}

Nor does it match the following message body:

{
   "customer_interests": ["rugby"]
}

Using a prefix with the anything-but operator

For string matching, you can also use a prefix with the anything-but operator.

For example, the following policy property denies the order- prefix:

"event":[{"anything-but": {"prefix": "order-"}}]

It matches either of the following attributes:

"event": {"Type": "String", "Value": "data-entry"}

"event": {"Type": "String", "Value": "order_number"}

It also matches either of the following message bodies:

{
   "event": "data-entry"
}

{
   "event": "order_number"
}

However, it doesn't match the following message attribute:

"event": {"Type": "String", "Value": "order-cancelled"}

Nor does it match the following message body:

{
   "event": "order-cancelled"
}

IP address matching

You can use the cidr operator to check whether an incoming message originates from a specific IP address or subnet.

Consider the following policy property:

"source_ip":[{"cidr": "10.0.0.0/24"}]

It matches either of the following message attributes:

"source_ip": {"Type": "String", "Value": "10.0.0.0"}

"source_ip": {"Type": "String", "Value": "10.0.0.255"}

It also matches either of the following message bodies:

{
   "source_ip": "10.0.0.0"
}

{
   "source_ip": "10.0.0.255"
}

However, it doesn't match the following message attribute:

"source_ip": {"Type": "String", "Value": "10.1.1.0"}

Nor does it match the following message body:

{
   "source_ip": "10.1.1.0"
}