概述

JBoss DMR 是 JBoss/WildFly/WildFly-swarm 底层用于数据交换传输的数据模型，本文主要从概念和示例两个方向去解释说明 JBoss DMR.

JBoss DMR

JBoss DMR(Dynamic Model Representation) is a siample management API of JBoss 7/WildFly. It’s key API is ModelNode which can be thought as a datastructure of all management activities. It has 2 main characteristics:

  • Dynamic Structure

  • JSON-like Format(can output JSON)

The following code snippet show how to form a ModelNode:

ModelNode node = new ModelNode();
node.get("description").set("A managable resource");
node.get("type").set(ModelType.OBJECT);
node.get("tail-comment-allowed").set(false);
node.get("attributes").get("foo").set("some description of foo");
node.get("attributes").get("bar").set("some description of bar");
node.get("attributes").get("list").add("value1");
node.get("attributes").get("list").add("value2");
node.get("attributes").get("list").add("value3");
node.get("value-type").get("size").set(ModelType.INT);
node.get("value-type").get("color").set(ModelType.STRING);
node.get("big-decimal-value").set(BigDecimal.valueOf(10.0));
node.get("big-integer-value").set(BigInteger.TEN);
node.get("bytes-value").set(new byte[] { (byte) 0, (byte) 55 });
node.get("double-value").set(Double.valueOf("55"));
node.get("max-double-value").set(Double.MAX_VALUE);
node.get("int-value").set(Integer.valueOf("12"));
node.get("max-int-value").set(Integer.MAX_VALUE);
node.get("long-value").set(Long.valueOf("14"));
node.get("max-long-value").set(Long.MAX_VALUE);
node.get("property-value").set("property", ModelType.PROPERTY);
node.get("expression-value").set(new ValueExpression("$expression"));
node.get("true-value").set(true);
node.get("false-value").set(false);

System.out.println(node);

Run the code will show it’s JSON-like Format:

{
    "description" => "A managable resource",
    "type" => OBJECT,
    "tail-comment-allowed" => false,
    "attributes" => {
        "foo" => "some description of foo",
        "bar" => "some description of bar",
        "list" => [
            "value1",
            "value2",
            "value3"
        ]
    },
    "value-type" => {
        "size" => INT,
        "color" => STRING
    },
    "big-decimal-value" => big decimal 10.0,
    "big-integer-value" => big integer 10,
    "bytes-value" => bytes {
        0x00, 0x37
    },
    "double-value" => 55.0,
    "max-double-value" => 1.7976931348623157E308,
    "int-value" => 12,
    "max-int-value" => 2147483647,
    "long-value" => 14L,
    "max-long-value" => 9223372036854775807L,
    "property-value" => ("property" => PROPERTY),
    "expression-value" => expression "$expression",
    "true-value" => true,
    "false-value" => false
}

In WildFly, all the management actions will be translated into the management commands that are encapsulated in the DMR format. For example, if we deploy cluster-demo.war to WildFly, it will send the following JSON-like DMR commands to the deployment module:

[{
    "operation" =>"composite",
    "address" => [],
    "steps" => [
    {
	"operation" =>"add",
	"address" => [("deployment" =>"cluster-demo.war")],
	"content" => [{
	    "path" =>"deployments/cluster-demo.war",
	    "relative-to" =>"jboss.server.base.dir",
	}],
    },
    {
	"operation" =>"deploy",
	"address" => [("deployment" =>"cluster-demo1.war")]
    }
}]

Key Method of ModelNode

String toString()
String toJSONString(false);
writeString(writer, false);
ModelNode formatAsJSON(writer, 0, true);
writeJSONString(writer, false);
ModelNode fromBase64(in);
long asLong()
long asLong(final long defVal)
int asInt()
int asInt(final int defVal)
boolean asBoolean()
boolean asBoolean(final boolean defVal)
String asString()
double asDouble()
double asDouble(final double defVal)
ModelType asType()

Examples

Example.1 - Form and Operate matrix Data

A matrix data, like a SQL Query, assuming a query have 2 columns and 2 rows.

final ModelNode outcome = new ModelNode();
outcome.get("outcome").set("success");
ModelNode resultsNode = new ModelNode();
ModelNode row1 = new ModelNode();
row1.get("column_1").set("value_11");
row1.get("column_2").set("value_12");
resultsNode.add(row1);
ModelNode row2 = new ModelNode();
row2.get("column_1").set("value_21");
row2.get("column_2").set("value_22");
resultsNode.add(row2);
outcome.get("result").set(resultsNode);

System.out.println(outcome);

List<ModelNode> list = outcome.get("result").asList();
System.out.println("column_1  column_2");
for(ModelNode rowNode : list) {
    System.out.println(rowNode.get("column_1").asString() + "  " + rowNode.get("column_2").asString());
}

Run above code the output like

{
    "outcome" => "success",
    "result" => [
        {
            "column_1" => "value_11",
            "column_2" => "value_12"
        },
        {
            "column_1" => "value_21",
            "column_2" => "value_22"
        }
    ]
}
column_1  column_2
value_11  value_12
value_21  value_22

Example.2 - WildFly interface

ModelNode interface = new ModelNode();
interface.get("interface").set("public");
ModelNode node = new ModelNode();
node.get(OP).set(ADD);
node.get(OP_ADDR).set("interface", interface);
node.get(INET_ADDRESS).set(new ValueExpression("${swarm.bind.address:0.0.0.0}"));

The WildFly interface looks

{
    "operation" => "add",
    "address" => ("interface" => "public"),
    "inet-address" => expression "${swarm.bind.address:0.0.0.0}"
}

Example.3 - WildFly Socket Binding Group

ModelNode node = new ModelNode();
PathAddress address = PathAddress.pathAddress("socket-binding-group", "default-sockets");
node.get(OP).set(ADD);
node.get(OP_ADDR).set(address.toModelNode());
node.get(DEFAULT_INTERFACE).set("public");
node.get(PORT_OFFSET).set(new ValueExpression("${swarm.port.offset:0}"));

The WildFly Socket Binding Group looks

{
    "operation" => "add",
    "address" => [("socket-binding-group" => "default-sockets")],
    "default-interface" => "public",
    "port-offset" => expression "${swarm.port.offset:0}"
}