Target Communication Framework Services - Run Control

Run Control Service

Version History

Version Date Change
0.1 2008-01-10 Initial contribution
1.0 2008-05-06 Approved
1.1 2012-05-30 TCF release 1.0
1.2 2016-02-03 TCF release 1.4

Overview

The service provides basic run control operations for execution contexts on a target. Command and event parameters are encoded as zero terminated JSON strings.

The service uses standard format for error reports, see Error Report Format.

Commands

All run control commands are fully asynchronous, which means they never wait until context is in a particular state. For example, if single step command arrives when context is running, it does not wait until it stops, but returns an error. If a command successfully resumed a context, it does not wait until instruction pointer reaches desired destination – from client point of view the command execution ends right after context was resumed. Various stepping commands can leave a context running in a special mode, which is different from normal execution, for example, it can leave temporary breakpoints to suspend the context when control reaches a particular place. Such execution mode ends when the context is suspended, even if it was suspended for reasons unrelated to the command and intended destination was not reached. Client can know when and why a context is suspended by listening to events.

Get Context


C • <token> • RunControl • getContext • <string: context ID> •

The command retrieves context properties for given context ID. Exact meaning of context depends on the target. A context can represent an execution thread, a process, an address space, etc. A context can belong to a parent context. Contexts hierarchy can be simple plain list or it can form a tree. It is up to target agent developers to choose layout that is most descriptive for a given target. Context IDs are valid across all services. In other words, all services access same hierarchy of contexts, with same IDs, however, each service accesses its own subset of context's attributes and functionality, which is relevant to that service.

Reply:


R • <token> • <error report> • <context data> •

<context data>
    ⇒ null
    ⇒ <object: context properties>

Context data object is collection of context properties. It should, at least, contain member "ID" : <string>. It can also contain arbitrary number of components describing context properties and capabilities. Context data is supposed to be cached by clients and it is not expected to change frequently. It can include, for example, context name or ability to perform single step command on the context. But, it should not include volatile data like current PC or running/suspended state. Service sends contextChanged event to notify changes in context data.

Predefined run control context properties are:

Get Children


C • <token> • RunControl • getChildren • <string: parent context ID> •

The command requests list of execution contexts available for run control commands.

Parent context ID can be null – to retrieve top level of the hierarchy, can be one of context IDs retrieved by previous getChildren commands, or it can be obtained from another service. Contexts hierarchy can be simple plain list or it can form a tree. It is up to target agent developers to choose layout that is most descriptive for a given target.

Reply:


R • <token> • <error report> • <array of context IDs> •

<array of context IDs>
    ⇒ null
    ⇒ [ <context ID list> ]

<context ID list>
    ⇒ <string: context ID>
    ⇒ <context ID list> , <string: context ID>

Suspend


C • <token> • RunControl • suspend • <string: context ID> •

The command suspends execution of given context. The command should fail if CanSuspend property of the context is false. If context's IsContainer = true, the command is propagated to context's children. Only contexts with HasState = true can be suspended.

Result message:


R • <token> • <error report> •

Resume


C • <token> • RunControl • resume • <string: context ID> • <int: mode> • <int: count> •
C • <token> • RunControl • resume • <string: context ID> • <int: mode> • <int: count> • <object: parameters> •

The command resumes execution of given context. The command should fail if CanResume property of the context is '0' for given mode. If context's IsContainer = true, the command is propagated to context's children. Only contexts with HasState = true can be resumed.

The command can have optional argument that contains set of resume parameters, for example stepping range definition.

Resume modes:

Resume parameters names:

Result message:


R • <token> • <error report> •

Get State


C • <token> • RunControl • getState • <string: context ID> •

The command retrieves current state of the context. The command should fail if HasState property of the context is false.

Result message:


R • <token> • <error report> • <boolean: suspended> •
    <int: PC> • <string: last state change reason> • <state data> •

<state data>
    ⇒ null
    ⇒ <object: context state properties>

State change reason can be any text, but if it is one of predefined strings, a generic client might be able to handle it better. Predefined reasons are:

Context state properties can contain any data relevant to context state. Definition of state properties depends on a target. Predefined properties are:

Get Min State


C • <token> • RunControl • getMinState • <string: context ID> •

This command is meant as a "minimal" alternative to the more costly Get State command. Get Min State can be faster, because it does not need to read program counter from the target. It can be used as an optimization by clients (e.g. Eclipse GUI) that need only minimal information about the run control state of a context, i.e. running/suspended and a reason for the latter

Result message:


R • <token> • <error report> • <boolean: suspended> •
    <string: last state change reason> • <state data> •

<state data>
    ⇒ null
    ⇒ <object: context state properties>

Terminate


C • <token> • RunControl • terminate • <string: context ID> •

The command terminates execution of given context. The command should fail if CanTerminate property of the context is false.

Result message:


R • <token> • <error report> •

Detach


C • <token> • RunControl • detach • <string: context ID> •

The command detaches debugger from the context. The command should fail if CanDetach property of the context is false.

Result message:


R • <token> • <error report> •

Events


E • RunControl • contextAdded • <array of context data> •

E • RunControl • contextChanged • <array of context data> •

E • RunControl • contextRemoved • <array of context IDs> •

E • RunControl • contextSuspended • <string: context ID> • <int: PC> •
        <string: reason> • <state data> •

E • RunControl • contextResumed • <string: context ID> •

E • RunControl • contextException • <string: context ID> • <string: description> •

E • RunControl • containerSuspended • <string: context ID> • <int: PC> •
        <string: reason> • <state data> • <array of context IDs> •

E • RunControl • containerResumed • <array of context IDs> •

E • RunControl • contextStateChanged • <string: context IDs> •

  <array of context data>
    ⇒ null
    ⇒ [ <context data list> ]

<context data list>
    ⇒ <object: context data>
    ⇒ <context data list> , <object: context data>
contextAdded
is sent when new contexts are created or attached for debugging. The message contains array of context data. Context data is same as returned by Get Context command.
contextChanged
is sent when context properties change. The message contains array of changed (new) context data. Context data is same as returned by Get Context command.
contextRemoved
is sent when context is removed - terminated or detached. The message contains array of context IDs.
contextSuspended
is sent when context is suspended. The message context ID contains context state data, same state data as returned by Get State command.
contextResumed
is sent when context is resumed. The message contains resumed context ID.
contextException
is sent when execution exception occurs in a context. The message contains context ID and a string that describes nature of the exception.
containerSuspended
is sent when target simultaneously suspends multiple threads in a container (process, core, etc.). The message contains context ID and context state data of a context responsible for the event. It can be container ID or any one of container children, for example, it can be thread that hit "suspend all" breakpoint. Message also contains full list of all contexts that were suspended simultaneously. No separate contextSuspened events are sent for contexts in the list. If client needs state data for those contexts, it should use Get State command.
containerResumed
is sent when target simultaneously resumes multiple threads in a container (process, core, etc.). Message contains full list of all contexts that were resumed simultaneously. No separate contextResumed events are sent for contexts in the list.
contextStateChanged
is sent when context state changes and the context is not and was not in suspended state. Changes to and from suspended state should be reported by other events: contextSuspended, contextResumed, containerSuspended, containerResumed.

API

/**
 * Run Control service provides basic run control operations for execution contexts on a target.
 *
 * @noimplement This interface is not intended to be implemented by clients.
 */
public interface IRunControl extends IService {

    /**
     * This service name, as it appears on the wire - a TCF name of the service.
     */
    static final String NAME = "RunControl";

    /* Context property names ---------------------------------------------- */

    static final String
        /** Run control context ID */
        PROP_ID = "ID",

        /** Context parent (owner) ID, for a thread it is same as process ID */
        PROP_PARENT_ID = "ParentID",

        /** Context process (memory space) ID */
        PROP_PROCESS_ID = "ProcessID",

        /** ID of a context that created this context */
        PROP_CREATOR_ID = "CreatorID",

        /** Human readable context name */
        PROP_NAME = "Name",

        /** true if the context is a container. Container can propagate run control commands to his children */
        PROP_IS_CONTAINER = "IsContainer",

        /** true if context has execution state - can be suspended/resumed */
        PROP_HAS_STATE = "HasState",

        /** Bit-set of RM_ values that are supported by the context */
        PROP_CAN_RESUME = "CanResume",

        /** Bit-set of RM_ values that can be used with count > 1 */
        PROP_CAN_COUNT = "CanCount",

        /** true if suspend command is supported by the context */
        PROP_CAN_SUSPEND = "CanSuspend",

        /** true if terminate command is supported by the context */
        PROP_CAN_TERMINATE = "CanTerminate",

        /** true if detach command is supported by the context */
        PROP_CAN_DETACH = "CanDetach",

        /** Context ID of a run control group that contains the context.
         * Members of same group are always suspended and resumed together:
         * resuming/suspending a context resumes/suspends all members of the group */
        PROP_RC_GROUP = "RCGroup",

        /** Context ID of a breakpoints group that contains the context.
         * Members of same group share same breakpoint instances:
         * a breakpoint is planted once for the group, no need to plant
         * the breakpoint for each member of the group */
        PROP_BP_GROUP = "BPGroup",

        /** Context ID of a symbols group that contains the context.
         * Members of a symbols group share same symbol reader configuration settings,
         * like user defined memory map entries and source lookup info */
        PROP_SYMBOLS_GROUP = "SymbolsGroup";

    /** @since 1.3 */
    static final String
        /** Array of String, the access types allowed for this context
         * when accessing context registers.
         */
        PROP_REG_ACCESS_TYPES = "RegAccessTypes";

    /**
     * Values of "RegAccessTypes".
     * @since 1.3
     */
    static final String
        REG_ACCESS_RD_RUNNING = "rd-running",   /** Context supports reading registers while running */
        REG_ACCESS_WR_RUNNUNG = "wr-running";   /** Context supports writing registers while running */

    /**
     * Values of "RegAccessTypes".
     * @since 1.4
     */
    static final String
        REG_ACCESS_RD_STOP = "rd-stop",         /** Debugger should stop the context to read registers */
        REG_ACCESS_WR_STOP = "wr-stop";         /** Debugger should stop the context to write registers */

    /**
     * Context resume modes.
     */
    static final int

        RM_RESUME = 0,

        /**
         * Step over a single instruction.
         * If the instruction is a function call then don't stop until the function returns.
         */
        RM_STEP_OVER = 1,

        /**
         * Step a single instruction.
         * If the instruction is a function call then stop at first instruction of the function.
         */
        RM_STEP_INTO = 2,

        /**
         * Step over a single source code line.
         * If the line contains a function call then don't stop until the function returns.
         */
        RM_STEP_OVER_LINE = 3,

        /**
         * Step a single source code line.
         * If the line contains a function call then stop at first line of the function.
         */
        RM_STEP_INTO_LINE = 4,

        /**
         * Run until control returns from current function.
         */
        RM_STEP_OUT = 5,

        /**
         * Start running backwards.
         * Execution will continue until suspended by command or breakpoint.
         */
        RM_REVERSE_RESUME = 6,

        /**
         * Reverse of RM_STEP_OVER - run backwards over a single instruction.
         * If the instruction is a function call then don't stop until get out of the function.
         */
        RM_REVERSE_STEP_OVER = 7,

        /**
         * Reverse of RM_STEP_INTO.
         * This effectively "un-executes" the previous instruction
         */
        RM_REVERSE_STEP_INTO = 8,

        /**
         * Reverse of RM_STEP_OVER_LINE.
         * Resume backward execution of given context until control reaches an instruction that belongs
         * to a different source line.
         * If the line contains a function call then don't stop until get out of the function.
         * Error is returned if line number information not available.
         */
        RM_REVERSE_STEP_OVER_LINE = 9,

        /**
         * Reverse of RM_STEP_INTO_LINE,
         * Resume backward execution of given context until control reaches an instruction that belongs
         * to a different line of source code.
         * If a function is called, stop at the beginning of the last line of the function code.
         * Error is returned if line number information not available.
         */
        RM_REVERSE_STEP_INTO_LINE = 10,

        /**
         * Reverse of RM_STEP_OUT.
         * Resume backward execution of the given context until control reaches the point where the current function was called.
         */
        RM_REVERSE_STEP_OUT = 11,

        /**
         * Step over instructions until PC is outside the specified range.
         * Any function call within the range is considered to be in range.
         */
        RM_STEP_OVER_RANGE = 12,

        /**
         * Step instruction until PC is outside the specified range for any reason.
         */
        RM_STEP_INTO_RANGE = 13,

        /**
         * Reverse of RM_STEP_OVER_RANGE
         */
        RM_REVERSE_STEP_OVER_RANGE = 14,

        /**
         * Reverse of RM_STEP_INTO_RANGE
         */
        RM_REVERSE_STEP_INTO_RANGE = 15,

        /**
         * Run until the context becomes active - scheduled to run on a target CPU
         */
        RM_UNTIL_ACTIVE = 16,

        /**
         * Run reverse until the context becomes active
         */
        RM_REVERSE_UNTIL_ACTIVE = 17;

    /**
     * State change reason of a context.
     * Reason can be any text, but if it is one of predefined strings,
     * a generic client might be able to handle it better.
     */
    static final String
        /** Context suspended by suspend command */
        REASON_USER_REQUEST = "Suspended",

        /** Context suspended by step command */
        REASON_STEP = "Step",

        /** Context suspended by breakpoint */
        REASON_BREAKPOINT = "Breakpoint",

        /** Context suspended by exception */
        REASON_EXCEPTION = "Exception",

        /** Context suspended as part of container */
        REASON_CONTAINER = "Container",

        /** Context suspended by watchpoint (data breakpoint) */
        REASON_WATCHPOINT = "Watchpoint",

        /** Context suspended because it received a signal */
        REASON_SIGNAL = "Signal",

        /** Context suspended because a shared library is loaded or unloaded */
        REASON_SHAREDLIB = "Shared Library",

        /** Context suspended because of an error in execution environment */
        REASON_ERROR = "Error";


    /* Optional parameters of context state -------------------------------- */

    /**
     * Context state parameter:
     * Integer - signal that caused the context to become suspended.
     */
    static final String STATE_SIGNAL = "Signal";

    /**
     * Context state parameter:
     * String - name of the signal that caused the context to become suspended.
     */
    static final String STATE_SIGNAL_NAME = "SignalName";

    /**
     * Context state parameter:
     * String - description of the signal that caused the context to become suspended.
     */
    static final String STATE_SIGNAL_DESCRIPTION = "SignalDescription";

    /**
     * Context state parameter:
     * Array of string - IDs of breakpoints that were triggered by the context.
     */
    static final String STATE_BREAKPOINT_IDS = "BPs";

    /**
     * Context state parameter:
     * Object - error report that describes a reason why program counter of the context is not available.
     */
    static final String STATE_PC_ERROR = "PCError";

    /**
     * Context state parameter:
     * Object - error report if last stepping operation failed to reach its destination.
     * @since 1.2
     */
    static final String STATE_STEP_ERROR = "StepError";

    /**
     * Context state parameter:
     * Boolean - true if the context is stopped by a function call injection.
     * @since 1.2
     */
    static final String STATE_FUNC_CALL = "FuncCall";

    /**
     * Context state parameter:
     * Boolean - true if the context is running in reverse.
     */
    static final String STATE_REVERSING = "Reversing";

    /**
     * Context state parameter:
     * String - name of a context that owns this context.
     */
    static final String STATE_CONTEXT = "Context";

    /**
     * Context state parameter:
     * String - name of CPU that is executing the context.
     */
    static final String STATE_CPU = "CPU";

    /**
     * Context state parameter:
     * String - name of current state if other than "Running", for example: "Sleeping", "Reset", "No Clock".
     */
    static final String STATE_NAME = "StateName";


    /* Optional parameters of resume command ------------------------------- */

    /**
     * Resume command parameter:
     * Integer - starting address of step range, inclusive.
     */
    static final String RP_RANGE_START = "RangeStart";

    /**
     * Resume command parameter:
     * Integer - ending address of step range, exclusive.
     */
    static final String RP_RANGE_END = "RangeEnd";

    /**
     * Resume command parameter:
     * Boolean - allow to stop in a hidden code during stepping.
     * @since 1.4
     */
    static final String RP_STEP_INTO_HIDDEN = "StepIntoHidden";


    /* Commands ------------------------------------------------------------ */

    /**
     * Retrieve context properties for given context ID.
     *
     * @param id - context ID.
     * @param done - callback interface called when operation is completed.
     */
    IToken getContext(String id, DoneGetContext done);

    /**
     * Client callback interface for getContext().
     */
    interface DoneGetContext {
        /**
         * Called when context data retrieval is done.
         * @param error - error description if operation failed, null if succeeded.
         * @param context - context data.
         */
        void doneGetContext(IToken token, Exception error, RunControlContext context);
    }

    /**
     * Retrieve children of given context.
     *
     * @param parent_context_id - parent context ID. Can be null -
     * to retrieve top level of the hierarchy, or one of context IDs retrieved
     * by previous getContext or getChildren commands.
     * @param done - callback interface called when operation is completed.
     */
    IToken getChildren(String parent_context_id, DoneGetChildren done);

    /**
     * Client callback interface for getChildren().
     */
    interface DoneGetChildren {
        /**
         * Called when context list retrieval is done.
         * @param error - error description if operation failed, null if succeeded.
         * @param context_ids - array of available context IDs.
         */
        void doneGetChildren(IToken token, Exception error, String[] context_ids);
    }

    /**
     * A context corresponds to an execution thread, process, address space, etc.
     * A context can belong to a parent context. Contexts hierarchy can be simple
     * plain list or it can form a tree. It is up to target agent developers to choose
     * layout that is most descriptive for a given target. Context IDs are valid across
     * all services. In other words, all services access same hierarchy of contexts,
     * with same IDs, however, each service accesses its own subset of context's
     * attributes and functionality, which is relevant to that service.
     * @noimplement This interface is not intended to be implemented by clients.
     */
    interface RunControlContext {

        /**
         * Get context properties. See PROP_* definitions for property names.
         * Context properties are read only, clients should not try to modify them.
         * @return Map of context properties.
         */
        Map<String,Object> getProperties();

        /**
         * Retrieve context ID.
         * Same as getProperties().get("ID")
         */
        String getID();

        /**
         * Retrieve parent context ID.
         * Same as getProperties().get("ParentID")
         */
        String getParentID();

        /**
         * Retrieve context process ID.
         * Same as getProperties().get("ProcessID")
         */
        String getProcessID();

        /**
         * Retrieve context creator ID.
         * Same as getProperties().get("CreatorID")
         */
        String getCreatorID();

        /**
         * Retrieve human readable context name.
         * Same as getProperties().get("Name")
         */
        String getName();

        /**
         * Utility method to read context property PROP_IS_CONTAINER.
         * Executing resume or suspend command on a container causes all its children to resume or suspend.
         * @return value of PROP_IS_CONTAINER.
         */
        boolean isContainer();

        /**
         * Utility method to read context property PROP_HAS_STATE.
         * Only context that has a state can be resumed or suspended.
         * @return value of PROP_HAS_STATE.
         */
        boolean hasState();

        /**
         * Utility method to read context property PROP_CAN_SUSPEND.
         * Value 'true' means suspend command is supported by the context,
         * however the method does not check that the command can be executed successfully in
         * the current state of the context. For example, the command still can fail if context is
         * already suspended.
         * @return value of PROP_CAN_SUSPEND.
         */
        boolean canSuspend();

        /**
         * Utility method to read a 'mode' bit in context property PROP_CAN_RESUME.
         * Value 'true' means resume command is supported by the context,
         * however the method does not check that the command can be executed successfully in
         * the current state of the context. For example, the command still can fail if context is
         * already resumed.
         * @param mode - resume mode, see RM_*.
         * @return value of requested bit of PROP_CAN_RESUME.
         */
        boolean canResume(int mode);

        /**
         * Utility method to read a 'mode' bit in context property PROP_CAN_COUNT.
         * Value 'true' means resume command with count other then 1 is supported by the context,
         * however the method does not check that the command can be executed successfully in
         * the current state of the context. For example, the command still can fail if context is
         * already resumed.
         * @param mode - resume mode, see RM_*.
         * @return value of requested bit of PROP_CAN_COUNT.
         */
        boolean canCount(int mode);

        /**
         * Utility method to read context property PROP_CAN_TERMINATE.
         * Value 'true' means terminate command is supported by the context,
         * however the method does not check that the command can be executed successfully in
         * the current state of the context. For example, the command still can fail if the context
         * already has exited.
         * @return value of PROP_CAN_TERMINATE.
         */
        boolean canTerminate();

        /**
         * Utility method to read context property PROP_CAN_DETACH.
         * Value 'true' means detach command is supported by the context,
         * however the method does not check that the command can be executed successfully in
         * the current state of the context. For example, the command still can fail if the context
         * already has exited.
         * @return value of PROP_CAN_DETACH.
         */
        boolean canDetach();

        /**
         * Utility method to read context property PROP_RC_GROUP -
         * context ID of a run control group that contains the context.
         * Members of same group are always suspended and resumed together:
         * resuming/suspending a context resumes/suspends all members of the group.
         * @return value of PROP_RC_GROUP.
         */
        String getRCGroup();

        /**
         * Utility method to read context property PROP_BP_GROUP -
         * context ID of a breakpoints group that contains the context.
         * Members of same group share same breakpoint instances:
         * a breakpoint is planted once for the group, no need to plant
         * the breakpoint for each member of the group
         * @return value of PROP_BP_GROUP or null if the context does not support breakpoints.
         */
        String getBPGroup();

        /**
         * Utility method to read context property PROP_SYMBOLS_GROUP -
         * context ID of a symbols group that contains the context.
         * Members of a symbols group share same symbol reader configuration settings,
         * like user defined memory map entries and source lookup info.
         * @return value of PROP_SYMBOLS_GROUP or null if the context is not a member of a symbols group.
         */
        String getSymbolsGroup();

        /**
         * Get the register access types allowed for this context.
         * @return collection of access type names.
         * @since 1.3
         */
        Collection<String> getRegAccessTypes();

        /**
         * Send a command to retrieve current state of a context.
         * @param done - command result call back object.
         * @return pending command handle, can be used to cancel the command.
         */
        IToken getState(DoneGetState done);

        /**
         * Send a command to retrieve current state of a context.
         * Similar to getState, but does not retrieve PC.
         * With some targets, it can be substantially faster.
         * @param done - command result call back object.
         * @return pending command handle, can be used to cancel the command.
         * @since 1.7
         */
        IToken getMinState(DoneGetMinState done);

        /**
         * Send a command to suspend a context.
         * Also suspends children if context is a container.
         * @param done - command result call back object.
         * @return pending command handle, can be used to cancel the command.
         */
        IToken suspend(DoneCommand done);

        /**
         * Send a command to resume a context.
         * Also resumes children if context is a container.
         * @param mode - defines how to resume the context, see RM_*.
         * @param count - if mode implies stepping, defines how many steps to perform.
         * @param done - command result call back object.
         * @return pending command handle, can be used to cancel the command.
         */
        IToken resume(int mode, int count, DoneCommand done);

        /**
         * Send a command to resume a context.
         * Also resumes children if context is a container.
         * @param mode - defines how to resume the context, see RM_*.
         * @param count - if mode implies stepping, defines how many steps to perform.
         * @param params - resume parameters, for example, step range definition, see RP_*.
         * @param done - command result call back object.
         * @return pending command handle, can be used to cancel the command.
         */
        IToken resume(int mode, int count, Map<String,Object> params, DoneCommand done);

        /**
         * Send a command to terminate a context.
         * @param done - command result call back object.
         * @return pending command handle, can be used to cancel the command.
         */
        IToken terminate(DoneCommand done);

        /**
         * Send a command to detach a context.
         * @param done - command result call back object.
         * @return pending command handle, can be used to cancel the command.
         */
        IToken detach(DoneCommand done);
    }

    interface DoneGetState {
        /**
         * Called when getState command execution is complete.
         * @param token - pending command handle.
         * @param error - command execution error or null.
         * @param suspended - true if the context is suspended
         * @param pc - program counter of the context (if suspended).
         * @param reason - suspend reason (if suspended), see REASON_*.
         * @param params - additional target specific data about context state, see STATE_*.
         */
        void doneGetState(IToken token, Exception error, boolean suspended, String pc,
                String reason, Map<String,Object> params);
    }

    /** @since 1.7 */
    interface DoneGetMinState {
        /**
         * Called when getMinState command execution is complete.
         * @param token - pending command handle.
         * @param error - command execution error or null.
         * @param suspended - true if the context is suspended
         * @param reason - suspend reason (if suspended), see REASON_*.
         * @param params - additional target specific data about context state, see STATE_*.
         */
        void doneGetMinState(IToken token, Exception error, boolean suspended,
                String reason, Map<String,Object> params);
    }

    interface DoneCommand {
        /**
         * Called when run control command execution is complete.
         * @param token - pending command handle.
         * @param error - command execution error or null.
         */
        void doneCommand(IToken token, Exception error);
    }

    /**
     * Add run control event listener.
     * @param listener - run control event listener to add.
     */
    void addListener(RunControlListener listener);

    /**
     * Remove run control event listener.
     * @param listener - run control event listener to remove.
     */
    void removeListener(RunControlListener listener);

    /**
     * Service events listener interface.
     */
    interface RunControlListener {

        /**
         * Called when new contexts are created.
         * @param contexts - array of new context properties.
         */
        void contextAdded(RunControlContext contexts[]);

        /**
         * Called when a context properties changed.
         * @param contexts - array of new context properties.
         */
        void contextChanged(RunControlContext contexts[]);

        /**
         * Called when contexts are removed.
         * @param context_ids - array of removed context IDs.
         */
        void contextRemoved(String context_ids[]);

        /**
         * Called when a thread is suspended.
         * @param context - ID of a context that was suspended.
         * @param pc - program counter of the context, can be null.
         * @param reason - human readable description of suspend reason.
         * @param params - additional, target specific data about suspended context.
         */
        void contextSuspended(String context, String pc,
                String reason, Map<String,Object> params);

        /**
         * Called when a thread is resumed.
         * @param context - ID of a context that was resumed.
         */
        void contextResumed(String context);

        /**
         * Called when target simultaneously suspends multiple threads in a container
         * (process, core, etc.).
         *
         * @param context - ID of a context responsible for the event. It can be container ID or
         * any one of container children, for example, it can be thread that hit "suspend all" breakpoint.
         * Client expected to move focus (selection) to this context.
         * @param pc - program counter of the context.
         * @param reason - suspend reason, see REASON_*.
         * @param params - additional target specific data about context state, see STATE_*.
         * @param suspended_ids - full list of all contexts that were suspended.
         */
        void containerSuspended(String context, String pc,
                String reason, Map<String,Object> params, String[] suspended_ids);

        /**
         * Called when target simultaneously resumes multiple threads in a container (process,
         * core, etc.).
         *
         * @param context_ids - full list of all contexts that were resumed.
         */
        void containerResumed(String[] context_ids);

        /**
         * Called when an exception is detected in a target thread.
         * @param context - ID of a context that caused an exception.
         * @param msg - human readable description of the exception.
         */
        void contextException(String context, String msg);
    }

    /**
     * Service events listener interface - extended.
     */
    interface RunControlListenerV1 extends RunControlListener {

        /**
         * Called when context state changes and the context is not and was not in suspended state.
         * Changes to and from suspended state should be reported by other events:
         * contextSuspended, contextResumed, containerSuspended, containerResumed.
         * @param context - ID of a context that changed state.
         */
        void contextStateChanged(String context);
    }
}