The Filter Namespace

The Filter Namespace provides the ability to declare Coherence Filters with in a Cache Configuration. It is typically used with other Namespaces that require Filters to be specified. In particular, the Filter Namespace is designed to allow declarative specification of the Coherence filters as documented in the API.

Namespace Content Handler

The implementation is provided by the com.oracle.coherence.environment.extensible.namespaces.FilterNamespaceContentHandler class.

Declaration

The common prefix used for this namespace in Cache Configurations is filter, however as with all XML namespace declarations this can be defined arbitrarily when declaring the namespace.

To use the namespace you should declare it as follows:

<cache-config xmlns:filter="class://com.oracle.coherence.environment.extensible.namespaces.FilterNamespaceContentHandler">

   ...

</cache-config>

Elements

The following section outlines the elements defined by this Namespace.

These are: all, always, and, any, custom, never, not, or, present, where and xor.

<filter:all>

The filter:all element defines an com.tangosol.util.filter.AllFilter.

Resolved Element Type:

When processed this element will be resolved to produce an com.tangosol.util.filter.AllFilter.

Child Elements:

This element requires zero or more child elements that each resolve to an instance of a com.tangosol.util.filter.Filter. Child elements are typically from this namespace and may be nested.

Examples:

An empty all filter:

<filter:all/>

A simple all filter:

<filter:all>
    <filter:and>
        ...
    </filter:and>
    <filter:or>
        ...
    </filter:or>
</filter:all>

<filter:always>

The filter:always element defines an com.tangosol.util.filter.AlwaysFilter.

Resolved Element Type:

When processed this element will be resolved to produce an com.tangosol.util.filter.AlwaysFilter.

Example:

An always filter:

<filter:always/>

<filter:and>

The filter:and element defines an com.tangosol.util.filter.AndFilter.

Resolved Element Type:

When processed this element will be resolved to produce an com.tangosol.util.filter.AndFilter.

Child Elements:

This element requires precisely two child elements that each resolve to an instance of a com.tangosol.util.filter.Filter. Child elements are typically from this namespace and may be nested.

Examples:

A simple and filter:

<filter:and>
    <filter:custom>...</filter:custom>
    <filter:all>...</filter:all>
</filter:and>

<filter:any>

The filter:any element defines an com.tangosol.util.filter.AnyFilter.

Resolved Element Type:

When processed this element will be resolved to produce an com.tangosol.util.filter.AnyFilter.

Child Elements:

This element requires zero or more child elements that each resolve to an instance of a com.tangosol.util.filter.Filter. Child elements are typically from this namespace and may be nested.

Examples:

An empty any filter:

<filter:any/>

A simple any filter:

<filter:any>
    <filter:and>
        ...
    </filter:and>
    <filter:or>
        ...
    </filter:or>
</filter:any>

<filter:custom>

The filter:custom element defines a com.tangosol.util.filter.Filter based on a ParameterizedBuilder<Filter>.

Resolved Element Type:

When processed this element will be resolved to produce a com.tangosol.util.filter.Filter.

Child Elements:

The child element of a filter:custom element must produce a ParameterizedBuilder<Filter>.

Examples:

A simple custom filter:

<filter:custom>
    <instance>
        <class-name>MyCustomFilter</class-name>
    </instance>
</filter:custom>

<filter:never>

The filter:never element defines an com.tangosol.util.filter.NeverFilter.

Resolved Element Type:

When processed this element will be resolved to produce a com.tangosol.util.filter.NeverFilter.

Child Elements:

(none)

Example:

A 'never' filter:

<filter:never/>

<filter:not>

The filter:not element defines a com.tangosol.util.filter.NotFilter.

Resolved Element Type:

When processed this element will be resolved to produce a com.tangosol.util.filter.NotFilter.

Child Elements:

This element requires precisely one child element, that of which resolves to an instance of a com.tangosol.util.filter.Filter. The child element is typically from this namespace and may be nested.

Examples:

A simple not filter:

<filter:not>
    <filter:and>
        ...
    </filter:and>
</filter:not>

<filter:or>

The filter:or element defines an com.tangosol.util.filter.OrFilter.

Resolved Element Type:

When processed this element will be resolved to produce an com.tangosol.util.filter.OrFilter.

Child Elements:

This element requires precisely two child elements that each resolve to an instance of a com.tangosol.util.filter.Filter. Child elements are typically from this namespace and may be nested.

Examples:

A simple or filter:

<filter:or>
    <filter:custom>...</filter:custom>
    <filter:all>...</filter:all>
</filter:or>

<filter:present>

The filter:present element defines a com.tangosol.util.filter.PresentFilter.

Resolved Element Type:

When processed this element will be resolved to produce a com.tangosol.util.filter.PresentFilter.

Child Elements:

(none)

Example:

A 'present' filter:

<filter:present/>

<filter:where>

The filter:where element defines a com.tangosol.util.filter.Filter based on a user-defined CohQL Where Clause.

Resolved Element Type:

When processed this element will be resolved to produce a com.tangosol.util.filter.Filter.

Child Elements:

(none)

Example:

A 'where' filter:

<filter:where>value() like "%Gudday World%"</filter:where>

<filter:xor>

The filter:xor element defines an com.tangosol.util.filter.XorFilter.

Resolved Element Type:

When processed this element will be resolved to produce an com.tangosol.util.filter.XorFilter.

Child Elements:

This element requires precisely two child elements that each resolve to an instance of a com.tangosol.util.filter.Filter. Child elements are typically from this namespace and may be nested.

Examples:

A simple xor filter:

<filter:xor>
    <filter:custom>...</filter:custom>
    <filter:all>...</filter:all>
</filter:xor>