<?xml version="1.0" encoding="UTF-8"?>
<!--
  ~ Copyright The WildFly Authors
  ~ SPDX-License-Identifier: Apache-2.0
  -->

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
           targetNamespace="urn:jboss:domain:modcluster:6.0"
           xmlns="urn:jboss:domain:modcluster:6.0"
           elementFormDefault="qualified"
           version="6.0">

    <xs:element name="subsystem" type="subsystem"/>

    <xs:complexType name="subsystem">
        <xs:sequence>
            <xs:element name="proxy" type="proxy" minOccurs="0" maxOccurs="unbounded">
                <xs:annotation>
                    <xs:documentation>
                        Proxy resource coupled with single Undertow listener (and server) specifying load balancer discovery,
                        its configuration and load balance factor provider. Multiple proxy configuration can be specified.
                    </xs:documentation>
                </xs:annotation>
            </xs:element>
        </xs:sequence>
    </xs:complexType>

    <xs:complexType name="proxy">
        <xs:sequence>
            <xs:choice minOccurs="0">
                <xs:element name="simple-load-provider" type="simple-load-provider">
                    <xs:annotation>
                        <xs:documentation>
                            Simple load provider returns constant pre-configured load balancing factor.
                        </xs:documentation>
                    </xs:annotation>
                </xs:element>
                <xs:element name="dynamic-load-provider" type="dynamic-load-provider">
                    <xs:annotation>
                        <xs:documentation>
                            Dynamic load provider computes the load balance factor of a node from a defined set of load metrics.
                        </xs:documentation>
                    </xs:annotation>
                </xs:element>
            </xs:choice>
        </xs:sequence>
        <xs:attribute name="name" type="xs:string" use="required">
            <xs:annotation>
                <xs:documentation>
                    Uniquely identifies this proxy configuration.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="advertise" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    Whether to enable multicast-based advertise mechanism.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="advertise-security-key" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    If specified, reverse proxy advertisements checksums will be verified using this value as a salt.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="advertise-socket" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    Name of socket binding to use for the advertise socket.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="auto-enable-contexts" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    If false, the contexts are registered with the reverse proxy as disabled; they need to be enabled manually
                    by 'enable-context' operation or via mod_cluster_manager console (if available).
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="balancer" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    The name of the balancer on the reverse proxy to register with.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="excluded-contexts" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    List of contexts to exclude from registration with the reverse proxies.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="flush-packets" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    Whether to enable packet flushing on the reverse proxy.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="flush-wait" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    Time to wait before flushing packets on the reverse proxy.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="listener" type="xs:string" use="required">
            <xs:annotation>
                <xs:documentation>
                    The name of Undertow listener that will be registered with the reverse proxy.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="load-balancing-group" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    Name of the load balancing group this node belongs to.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="max-attempts" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    Maximum number of failover attempts by reverse proxy when sending the request to the backend server.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="node-timeout" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    Timeout (in seconds) for proxy connections to a node. That is the time mod_cluster will wait for the
                    back-end response before returning an error.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="ping" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    Number of seconds for which to wait for a pong answer to a ping.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="proxies">
            <xs:annotation>
                <xs:documentation>
                    List of reverse proxies for mod_cluster to register with defined by 'outbound-socket-binding' in
                    'socket-binding-group'.
                </xs:documentation>
            </xs:annotation>
            <xs:simpleType>
                <xs:list itemType="xs:string"/>
            </xs:simpleType>
        </xs:attribute>
        <xs:attribute name="proxy-url" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    Base URL for MCMP requests.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="session-draining-strategy" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    Session draining strategy used during undeployment of a web application.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="smax" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    Soft maximum idle connection count for reverse proxy.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="socket-timeout" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    Timeout to wait for the reverse proxy to answer a MCMP message.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="ssl-context" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    Reference to the SSLContext to be used by mod_cluster.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="status-interval" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    Number of seconds a STATUS message is sent from the application server to the proxy.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="sticky-session" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    Indicates whether subsequent requests for a given session should be routed to the same node, if possible.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="sticky-session-force" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    Indicates whether the reverse proxy should run an error in the event that the balancer is unable to route a
                    request to the node to which it is stuck. Ignored if sticky sessions are disabled.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="sticky-session-remove" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    Indicates whether the reverse proxy should remove session stickiness in the event that the balancer is
                    unable to route a request to the node to which it is stuck. Ignored if sticky sessions are disabled.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="stop-context-timeout" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    Maximum time to wait for context to process pending requests.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="ttl" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    Time to live (in seconds) for idle connections above smax.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="worker-timeout" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    Number of seconds to wait for a worker to become available to handle a request.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
    </xs:complexType>

    <xs:complexType name="simple-load-provider">
        <xs:attribute name="factor" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    Constant pre-configured load balancing factor.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
    </xs:complexType>

    <xs:complexType name="dynamic-load-provider">
        <xs:choice minOccurs="0" maxOccurs="unbounded">
            <xs:element name="load-metric" type="load-metric">
                <xs:annotation>
                    <xs:documentation>
                        Built-in load metric contributing a value to the overall load factor of a node. The load factors from
                        each metric are aggregated according to their weights.
                    </xs:documentation>
                </xs:annotation>
            </xs:element>
            <xs:element name="custom-load-metric" type="custom-load-metric">
                <xs:annotation>
                    <xs:documentation>
                        Custom load metric loaded from a specified Java class contributing a value to the overall load factor of
                        a node. The load factors from each metric are aggregated according to their weights.
                    </xs:documentation>
                </xs:annotation>
            </xs:element>
        </xs:choice>
        <xs:attribute name="history" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    The number of historic (previous) load values to consider in the load balance factor computation.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="decay" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    The factor by which a historic load values should degrade in significance.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="initial-load" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    Initial load within the range [0..100] with which to prepopulate historical values. Used to gradually drive
                    load to the node. Value of 0 prepopulates with full load and value of -1 disables this behavior.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
    </xs:complexType>

    <xs:complexType name="common-load-metric" abstract="true">
        <xs:choice minOccurs="0" maxOccurs="unbounded">
            <xs:element name="property" type="property">
                <xs:annotation>
                    <xs:documentation>
                        Properties to apply on a loaded metric instance.
                    </xs:documentation>
                </xs:annotation>
            </xs:element>
        </xs:choice>
        <xs:attribute name="weight" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    Number indicating the significance of a metric with respect to the other metrics. For example, a metric of
                    weight 2 will have twice the impact on the overall load factor than a metric of weight 1.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
        <xs:attribute name="capacity" type="xs:string">
            <xs:annotation>
                <xs:documentation>
                    Maximum capacity of the metric used to normalize the load values from a metric which require explicit
                    capacity.
                </xs:documentation>
            </xs:annotation>
        </xs:attribute>
    </xs:complexType>

    <xs:complexType name="load-metric">
        <xs:complexContent>
            <xs:extension base="common-load-metric">
                <xs:attribute name="type" type="load-metric-enumeration" use="required">
                    <xs:annotation>
                        <xs:documentation>
                            Type of a built-in load metric from the enumerated values.
                        </xs:documentation>
                    </xs:annotation>
                </xs:attribute>
            </xs:extension>
        </xs:complexContent>
    </xs:complexType>

    <xs:complexType name="custom-load-metric">
        <xs:complexContent>
            <xs:extension base="common-load-metric">
                <xs:attribute name="class" type="xs:string" use="required">
                    <xs:annotation>
                        <xs:documentation>
                            Class name to use to construct a load metric from.
                        </xs:documentation>
                    </xs:annotation>
                </xs:attribute>
                <xs:attribute name="module" type="xs:string">
                    <xs:annotation>
                        <xs:documentation>
                            Module name from which to load the load metric class.
                        </xs:documentation>
                    </xs:annotation>
                </xs:attribute>
            </xs:extension>
        </xs:complexContent>
    </xs:complexType>

    <xs:simpleType name="load-metric-enumeration">
        <xs:restriction base="xs:token">
            <xs:enumeration value="cpu">
                <xs:annotation>
                    <xs:documentation>
                        Returns CPU load as percentage.
                    </xs:documentation>
                </xs:annotation>
            </xs:enumeration>
            <xs:enumeration value="heap">
                <xs:annotation>
                    <xs:documentation>
                        Returns the heap memory usage as a percentage of max heap size.
                    </xs:documentation>
                </xs:annotation>
            </xs:enumeration>
            <xs:enumeration value="sessions">
                <xs:annotation>
                    <xs:documentation>
                        Returns number of active sessions consulting the session manager. Requires an explicit capacity.
                    </xs:documentation>
                </xs:annotation>
            </xs:enumeration>
            <xs:enumeration value="requests">
                <xs:annotation>
                    <xs:documentation>
                        Returns the number of requests per second. Requires an explicit capacity.
                    </xs:documentation>
                </xs:annotation>
            </xs:enumeration>
            <xs:enumeration value="send-traffic">
                <xs:annotation>
                    <xs:documentation>
                        Returns the outgoing request traffic in KB per second. Requires an explicit capacity.
                    </xs:documentation>
                </xs:annotation>
            </xs:enumeration>
            <xs:enumeration value="receive-traffic">
                <xs:annotation>
                    <xs:documentation>
                        Returns the incoming request POST traffic in KB per second (the application needs to read POST data).
                        Requires an explicit capacity.
                    </xs:documentation>
                </xs:annotation>
            </xs:enumeration>
            <xs:enumeration value="busyness">
                <xs:annotation>
                    <xs:documentation>
                        Returns the number of currently busy listener threads servicing requests. Requires an explicit capacity.
                    </xs:documentation>
                </xs:annotation>
            </xs:enumeration>
        </xs:restriction>
    </xs:simpleType>

    <xs:complexType name="property">
        <xs:attribute name="name" type="xs:string" use="required"/>
        <xs:attribute name="value" type="xs:string" use="required"/>
    </xs:complexType>

</xs:schema>
