Filters

What are Filters?

A filter is a property of a subscriber that enables that subscriber to receive only that content that meets certain criteria. Filters can be used to exclude content that the subscriber is not interested in, or that the subscriber's computing resources cannot handle. Filters can be defined based on the entry type, MIME type, or one or more name/value pairs that are defined for the content. A filter can be an include filter, which means that the subscriber receives all content that meets the filter criteria, or an exclude filter, which means that the subscriber receives all content that does not meet the filter criteria.

Notes:

• For each type of filter (entry type, MIME type, or name/value pair), you can define either inclusion or exclusion filters (but not both). If you have previously defined exclusion name/value filters, for example, and then specify an inclusion filter, then all of the previously defined exclusion filters are deleted from the repository.

• The SAS Information Delivery Portal does not currently support subscription filters.

Entry Filters

Each published package contains one or more entries. Each entry is one of several possible types. You can create a filter to include or exclude one or more entry types. Valid entry types include the following:

MIME Type Filters

MIME types provide details about the information that is being published. For example, specifying the MIME type audio/basic indicates that the file is an audio file and requires software that can interpret such content.

You can define a filter that determines the type of information the subscriber receives. For example, a subscriber who is connecting with a modem might not want to receive some data types that may be large or unwieldy, such as movies or audio. By excluding those MIME types, the subscriber never encounters those types of information.

Some common MIME types include the following:

Name/Value Pair Filters

Publishers can specify name/value pairs that describe the package that is being published. Knowledge of name/value pairs enables you to define filters for a subscriber that determine the packages that are received. If an inclusion name/value filter is defined for a subscriber, then the subscriber will receive only those packages that match the name/value filter.

A name/value pair is expressed as either a name or a relationship between a name and a value in the form

name < operator value >

• name is a variable to which a value can be assigned. name is not case-sensitive.
• operator relates the variable to the value. Commonly used operators are as follows:

  Comparison Operators	Logical Operators
  = (equals)	& (AND)
  != (not equal)	| (OR)
  ? (contains)

• value is a character string or numeric value. value is case-sensitive.

Examples:

The following is an example of a package description using name/value pairs that a publisher has assigned to a published package:

   market=(Mexico, US) type=report Quarter4 sales _priority_=low

market=(US, Asia, Europe)

No match. Because the equals comparison operator (=) is used, the subscriber values and the publisher values that are assigned to the variable name MARKET must match exactly. In this example, the subscriber filters for US, Asia, and Europe, whereas the publisher assigns a value of Mexico and US. The conditions for selection are not met. Therefore, the package is not delivered to the subscriber.

market=(mexico, us)

No match. Because the equals comparison operator (=) is used, the subscriber values and the publisher values that are assigned to the variable name MARKET must match exactly. In this example, the subscriber values do not match the publisher values because of case differences.

market=US | market=Asia | market=Mexico

No match. Because the equals comparison operator (=) is used, the subscriber values and the publisher values that are assigned to the variable name MARKET must match exactly. In this example, although the OR operator (|) might seem to cause a matching condition, the equals operator (=) requires that each name/value pair that is separated by an OR operator (|) match the publisher name/value pair entirely. A match would result if the subscriber values were written as follows:

market=Mexico, US | market=Asia | market=Mexico 

The first name/value pair in the series would match.

market=(Mexico, US)

Match. Because the equals comparison operator (=) is used, the subscriber values and the publisher values that are assigned to the variable name MARKET must match exactly. In this example, the value set does match.

market=(US, Mexico)

Match. Because the equals comparison operator (=) is used, the subscriber values and the publisher values that are assigned to the variable name MARKET must match exactly. In this example, the value set matches, regardless of the order of values within the value set.

market?US & market?Asia & market?Mexico

No match. The conditions that are specified in the subscriber name/value pair read: Variable name MARKET must contain the values US and Asia and Mexico. The contains comparison operator (?) identifies the eligible values for consideration. In this example, although the publisher variable MARKET contains US and Mexico, it does not also contain Asia. Because the logical AND operator (&) is used, its condition is not satisfied.

market?US | market?Asia | market?Mexico

Match. The conditions that are specified in the subscriber name/value pair read: Variable name MARKET must contain the values US or Asia or Mexico. The contains comparison operator (?) identifies the eligible values for consideration. In this example, the publisher variable MARKET contains US, and the logical OR operator (|) condition is satisfied.

Quarter4=sales

No match. Because the equals comparison operator (=) is used, the subscriber values and the publisher values that are assigned to the variable name QUARTER4 must match exactly. In this example, because the publisher variable name QUARTER4 does not contain a value and the subscriber variable name QUARTER4 does contain a value of sales, the value sets do not match.

Quarter4

Match Variable names are not required to have values. In this example, because the publisher variable name QUARTER4 does not have an assigned value and the subscriber variable name QUARTER4 does not have an assigned value, the value sets match.

type=report & forecast

No match. Two conditions must be met. The equals comparison operator (=) requires that the subscriber values and the publisher values that are assigned to variable name TYPE match. In this example, the first condition is met because both the publisher and the subscriber assign the value report to variable TYPE. However, the AND logical operator (&) requires that the variable name TYPE also be assigned the value forecast. Because the publisher variable name TYPE is not assigned a value of forecast, the final condition is not met.

type=report & sales

Match. Two conditions must be met. The equals comparison operator (=) requires that the subscriber value and the publisher value that are assigned to variable name TYPE match. In this example, the values match. Both assign the value report to the variable name TYPE. The AND logical operator (&) also requires that the variable name SALES match. Because both the publisher and the subscriber identify a variable name sales with no assigned value, the final condition is also met.