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package com.sun.jdi;

import com.sun.jdi.connect.*;

import com.sun.jdi.connect.spi.Connection;

import java.util.List;

import java.io.IOException;

/**

 * A manager of connections to target virtual machines. The

 * VirtualMachineManager allows one application to debug

 * multiple target VMs. (Note that the converse is not

 * supported; a target VM can be debugged by only one

 * debugger application.) This interface

 * contains methods to manage connections

 * to remote target VMs and to obtain the {@link VirtualMachine}

 * mirror for available target VMs.

 * <p>

 * Connections can be made using one of several different

 * {@link com.sun.jdi.connect.Connector} objects. Each connector encapsulates

 * a different way of connecting the debugger with a target VM.

 * <p>

 * The VirtualMachineManager supports many different scenarios for

 * connecting a debugger to a virtual machine. Four examples

 * are presented in the table below. The

 * examples use the command line syntax in Sun's implementation.

 * Some {@link com.sun.jdi.connect.Connector} implementations may require slightly

 * different handling than presented below.

 * <p>

 * <TABLE BORDER WIDTH="75%" SUMMARY="Four scenarios for connecting a debugger

 *  to a virtual machine">

 * <TR>

 * <TH scope=col>Scenario</TH>

 * <TH scope=col>Description</TH>

 * <TR>

 * <TD>Debugger launches target VM (simplest, most-common scenario)</TD>

 *

 * <TD>Debugger calls the

 * {@link com.sun.jdi.connect.LaunchingConnector#launch(java.util.Map)}

 * method of the default connector, obtained with {@link #defaultConnector}. The

 * target VM is launched, and a connection between that VM and the

 * debugger is established. A {@link VirtualMachine} mirror is returned.

 * <P>Or, for more control

 * <UL>

 * <LI>

 * Debugger selects a connector from the list returned by

 * {@link #launchingConnectors} with desired characteristics

 * (for example, transport type, etc.).

 * <LI>

 * Debugger calls the

 * {@link com.sun.jdi.connect.LaunchingConnector#launch(java.util.Map)}

 * method of the selected connector. The

 * target VM is launched, and a connection between that VM and the

 * debugger is established. A {@link VirtualMachine} mirror is returned.

 * </UL>

 * </TD>

 * </TR>

 * <TR>

 * <TD>Debugger attaches to previously-running VM</TD>

 * <TD>

 * <UL>

 * <LI>

 * Target VM is launched using the options

 * <code>-agentlib:jdwp=transport=xxx,server=y</code>

 * </LI>

 * <LI>

 * Target VM generates and outputs the tranport-specific address at which it will

 * listen for a connection.</LI>

 * <LI>

 * Debugger is launched. Debugger selects a connector in the list

 * returned by {@link #attachingConnectors} matching the transport with

 * the name "xxx".

 * <LI>

 * Debugger presents the default connector parameters (obtained through

 * {@link com.sun.jdi.connect.Connector#defaultArguments()}) to the end user,

 * allowing the user to

 * fill in the transport-specific address generated by the target VM.

 * <LI>

 * Debugger calls the {@link com.sun.jdi.connect.AttachingConnector#attach(java.util.Map)} method

 * of the selected to attach to the target VM. A {@link VirtualMachine}

 * mirror is returned.

 * </UL>

 * </TD>

 * </TR>

 *

 * <TR>

 * <TD>Target VM attaches to previously-running debugger</TD>

 * <TD>

 * <LI>

 * At startup, debugger selects one or more connectors from

 * the list returned by {@link #listeningConnectors} for one or more

 * transports.</LI>

 * <LI>

 * Debugger calls the {@link com.sun.jdi.connect.ListeningConnector#startListening(java.util.Map)} method for each selected

 * connector. For each call, a transport-specific address string is

 * generated and returned. The debugger makes the transport names and

 * corresponding address strings available to the end user.

 * <LI>

 * Debugger calls

 * {@link com.sun.jdi.connect.ListeningConnector#accept(java.util.Map)}

 * for each selected connector to wait for

 * a target VM to connect.</LI>

 * <LI>

 * Later, target VM is launched by end user with the options

 * <code>-agentlib:jdwp=transport=xxx,address=yyy</code>

 * where "xxx" the transport for one of the connectors selected by the

 * the debugger and "yyy"

 * is the address generated by

 * {@link com.sun.jdi.connect.ListeningConnector#accept(java.util.Map)} for that

 * transport.</LI>

 * <LI>

 * Debugger's call to {@link com.sun.jdi.connect.ListeningConnector#accept(java.util.Map)} returns

 * a {@link VirtualMachine} mirror.</LI>

 * </TD>

 * </TR>

 *

 * <TR>

 * <TD>Target VM launches debugger (sometimes called "Just-In-Time" debugging)</TD>

 * <TD>

 * <LI>

 * Target VM is launched with the options

 * <code>-agentlib:jdwp=launch=cmdline,onuncaught=y,transport=xxx,server=y</code>

 * </LI>

 * <LI>

 * Later, an uncaught exception is thrown in the target VM. The target

 * VM generates the tranport-specific address at which it will

 * listen for a connection.

 * <LI>Target VM launches the debugger with the following items concatenated

 * together (separated by spaces) to form the command line:

 * <UL>

 * <LI> The launch= value

 * <LI> The transport= value

 * <LI> The generated transport-specific address at which VM is listening for

 * debugger connection.

 * </UL>

 * <LI>

 * Upon launch, debugger selects a connector in the list

 * returned by {@link #attachingConnectors} matching the transport with

 * the name "xxx".

 * <LI>

 * Debugger changes the default connector parameters (obtained through

 * {@link com.sun.jdi.connect.Connector#defaultArguments()}) to specify

 * the transport specific address at which the VM is listenig. Optionally,

 * other connector arguments can be presented to the user.

 * <LI>

 * Debugger calls the

 * {@link com.sun.jdi.connect.AttachingConnector#attach(java.util.Map)} method

 * of the selected to attach to the target VM. A {@link VirtualMachine}

 * mirror is returned.

 * </TD>

 * </TR>

 * </TABLE>

 *

 * <p> Connectors are created at start-up time. That is, they

 * are created the first time that {@link

 * com.sun.jdi.Bootstrap#virtualMachineManager()} is invoked.

 * The list of all Connectors created at start-up time can be

 * obtained from the VirtualMachineManager by invoking the

 * {@link #allConnectors allConnectors} method.

 *

 * <p> Connectors are created at start-up time if they are

 * installed on the platform. In addition, Connectors are created

 * automatically by the VirtualMachineManager to encapsulate any

 * {@link com.sun.jdi.connect.spi.TransportService} implementations

 * that are installed on the platform. These two mechanisms for

 * creating Connectors are described here.

 *

 * <p> A Connector is installed on the platform if it is installed

 * in a jar file that is visible to the defining class loader of

 * the {@link com.sun.jdi.connect.Connector} type,

 * and that jar file contains a provider configuration file named

 * <tt>com.sun.jdi.connect.Connector</tt> in the resource directory

 * <tt>META-INF/services</tt>, and the provider configuration file

 * lists the full-qualified class name of the Connector

 * implementation. A Connector is a class that implements the

 * {@link com.sun.jdi.connect.Connector Connector} interface. More

 * appropriately the class implements one of the specific Connector

 * types, namely {@link com.sun.jdi.connect.AttachingConnector

 * AttachingConnector}, {@link com.sun.jdi.connect.ListeningConnector

 * ListeningConnector}, or {@link com.sun.jdi.connect.LaunchingConnector

 * LaunchingConnector}. The format of the provider configuration file

 * is one fully-qualified class name per line. Space and tab characters

 * surrounding each class, as well as blank lines are ignored. The

 * comment character is <tt>'#'</tt> (<tt>0x23</tt>), and on each

 * line all characters following the first comment character are

 * ignored. The file must be encoded in UTF-8.

 *

 * <p> At start-up time the VirtualMachineManager attempts to load

 * and instantiate (using the no-arg constructor) each class listed

 * in the provider configuration file. Exceptions thrown when loading

 * or creating the Connector are caught and ignored. In other words,

 * the start-up process continues despite of errors.

 *

 * <p> In addition to Connectors installed on the platform the

 * VirtualMachineManager will also create Connectors to encapsulate

 * any {@link com.sun.jdi.connect.spi.TransportService} implementations

 * that are installed on the platform. A TransportService is

 * installed on the platform if it installed in a jar file that is

 * visible to the defining class loader for the

 * {@link com.sun.jdi.connect.spi.TransportService} type, and that jar

 * file contains a provider configuration file named

 * <tt>com.sun.jdi.connect.spi.TransportService</tt> in the resource

 * directory <tt>META-INF/services</tt>, and the provider

 * configuration file lists the the full-qualified class name of the

 * TransportService implementation. A TransportService is a concrete

 * sub-class of {@link com.sun.jdi.connect.spi.TransportService

 * TransportService}. The format of the provider configuration file

 * is the same as the provider configuration file for Connectors

 * except that each class listed must be the fully-qualified class

 * name of a class that implements the TransportService interface.

 *

 * <p> For each TransportService installed on the platform, the

 * VirtualMachineManager creates a corresponding

 * {@link com.sun.jdi.connect.AttachingConnector} and

 * {@link com.sun.jdi.connect.ListeningConnector}. These

 * Connectors are created to encapsulate a {@link

 * com.sun.jdi.connect.Transport Transport} that in turn

 * encapsulates the TransportService.

 * The AttachingConnector will be named based on the name of the

 * transport service concatenated with the string <tt>Attach</tt>.

 * For example, if the transport service {@link

 * com.sun.jdi.connect.spi.TransportService#name() name()} method

 * returns <tt>telepathic</tt> then the AttachingConnector will

 * be named <tt>telepathicAttach</tt>. Similiarly the ListeningConnector

 * will be named with the string <tt>Listen</tt> tagged onto the

 * name of the transport service. The {@link

 * com.sun.jdi.connect.Connector#description() description()} method

 * of both the AttachingConnector, and the ListeningConnector, will

 * delegate to the {@link com.sun.jdi.connect.spi.TransportService#description()

 * description()} method of the underlying transport service. Both

 * the AttachingConnector and the ListeningConnector will have two

 * Connector {@link com.sun.jdi.connect.Connector$Argument Arguments}.

 * A {@link com.sun.jdi.connect.Connector$StringArgument StringArgument}

 * named <tt>address</tt> is the connector argument to specify the

 * address to attach too, or to listen on. A

 * {@link com.sun.jdi.connect.Connector$IntegerArgument IntegerArgument}

 * named <tt>timeout</tt> is the connector argument to specify the

 * timeout when attaching, or accepting. The timeout connector may be

 * ignored depending on if the transport service supports an attach

 * timeout or accept timeout.

 *

 * <p> Initialization of the virtual machine manager will fail, that is

 * {@link com.sun.jdi.Bootstrap#virtualMachineManager()} will throw an

 * error if the virtual machine manager is unable to create any

 * connectors.

 *

 * @author Gordon Hirsch

 * @since  1.3

 */

@jdk.Exported

public interface VirtualMachineManager {

    /**

     * Identifies the default connector. This connector should

     * be used as the launching connector when selection of a

     * connector with specific characteristics is unnecessary.

     *

     * @return the default {@link com.sun.jdi.connect.LaunchingConnector}

     */

    LaunchingConnector defaultConnector();

    /**

     * Returns the list of known {@link com.sun.jdi.connect.LaunchingConnector} objects.

     * Any of the returned objects can be used to launch a new target

     * VM and immediately create a {@link VirtualMachine} mirror for it.

     *

     * Note that a target VM launched by a launching connector is not

     * guaranteed to be stable until after the {@link com.sun.jdi.event.VMStartEvent} has been

     * received.

     * @return a list of {@link com.sun.jdi.connect.LaunchingConnector} objects.

     */

    List<LaunchingConnector> launchingConnectors();

    /**

     * Returns the list of known {@link com.sun.jdi.connect.AttachingConnector} objects.

     * Any of the returned objects can be used to attach to an existing target

     * VM and create a {@link VirtualMachine} mirror for it.

     *

     * @return a list of {@link com.sun.jdi.connect.AttachingConnector} objects.

     */

    List<AttachingConnector> attachingConnectors();

    /**

     * Returns the list of known {@link com.sun.jdi.connect.ListeningConnector} objects.

     * Any of the returned objects can be used to listen for a

     * connection initiated by a target VM

     * and create a {@link VirtualMachine} mirror for it.

     *

     * @return a list of {@link com.sun.jdi.connect.ListeningConnector} objects.

     */

    List<ListeningConnector> listeningConnectors();

    /**

     * Returns the list of all known {@link com.sun.jdi.connect.Connector} objects.

     *

     * @return a list of {@link com.sun.jdi.connect.Connector} objects.

     */

     List<Connector> allConnectors();

    /**

     * Lists all target VMs which are connected to the debugger.

     * The list includes {@link VirtualMachine} instances for

     * any target VMs which initiated a connection

     * and any

     * target VMs to which this manager has initiated a connection.

     * A target VM will remain in this list

     * until the VM is disconnected.

     * {@link com.sun.jdi.event.VMDisconnectEvent} is placed in the event queue

     * after the VM is removed from the list.

     *

     * @return a list of {@link VirtualMachine} objects, each mirroring

     * a target VM.

     */

     List<VirtualMachine> connectedVirtualMachines();

     /**

      * Returns the major version number of the JDI interface.

      * See {@link VirtualMachine#version} target VM version and

      * information and

      * {@link VirtualMachine#description} more version information.

      *

      * @return the integer major version number.

      */

     int majorInterfaceVersion();

     /**

      * Returns the minor version number of the JDI interface.

      * See {@link VirtualMachine#version} target VM version and

      * information and

      * {@link VirtualMachine#description} more version information.

      *

      * @return the integer minor version number

      */

     int minorInterfaceVersion();

     /**

      * Create a virtual machine mirror for a target VM.

      *

      * <p> Creates a virtual machine mirror for a target VM

      * for which a {@link com.sun.jdi.connect.spi.Connection Connection}

      * already exists. A Connection is created when a {@link

      * com.sun.jdi.connect.Connector Connector} establishes

      * a connection and successfully handshakes with a target VM.

      * A Connector can then use this method to create a virtual machine

      * mirror to represent the composite state of the target VM.

      *

      * <p> The <tt>process</tt> argument specifies the

      * {@link java.lang.Process} object for the taget VM. It may be

      * specified as <tt>null</tt>. If the target VM is launched

      * by a {@link com.sun.jdi.connect.LaunchingConnector

      * LaunchingConnector} the <tt>process</tt> argument should be

      * specified, otherwise calling {@link com.sun.jdi.VirtualMachine#process()}

      * on the created virtual machine will return <tt>null</tt>.

      *

      * <p> This method exists so that Connectors may create

      * a virtual machine mirror when a connection is established

      * to a target VM. Only developers creating new Connector

      * implementations should need to make direct use of this

      * method. </p>

      *

      * @param  connection

      *         The open connection to the target VM.

      *

      * @param  process

      *         If launched, the {@link java.lang.Process} object for

      *         the target VM. <tt>null</tt> if not launched.

      *

      * @return new virtual machine representing the target VM.

      *

      * @throws IOException

      *         if an I/O error occurs

      *

      * @throws IllegalStateException

      *         if the connection is not open

      *

      * @see com.sun.jdi.connect.spi.Connection#isOpen()

      * @see com.sun.jdi.VirtualMachine#process()

      *

      * @since 1.5

      */

     VirtualMachine createVirtualMachine(Connection connection, Process process) throws IOException;

     /**

      * Creates a new virtual machine.

      *

      * <p> This convenience method works as if by invoking {@link

      * #createVirtualMachine(Connection, Process)} method and

      * specifying <tt>null</tt> as the <tt>process</tt> argument.

      *

      * <p> This method exists so that Connectors may create

      * a virtual machine mirror when a connection is established

      * to a target VM. Only developers creating new Connector

      * implementations should need to make direct use of this

      * method. </p>

      *

      * @return the new virtual machine

      *

      * @throws IOException

      *         if an I/O error occurs

      *

      * @throws IllegalStateException

      *         if the connection is not open

      *

      * @since 1.5

      */

     VirtualMachine createVirtualMachine(Connection connection) throws IOException;

}