Java^TM Debug Wire Protocol
Specification Details


string	description	Text information on the VM version
int	jdwpMajor	Major JDWP Version number
int	jdwpMinor	Minor JDWP Version number
string	vmVersion	Target VM JRE version, as in the java.version property
string	vmName	Target VM name, as in the java.vm.name property

Error Data

VM_DEAD

The virtual machine is not running.

ClassesBySignature Command (2)

Returns reference types for all the classes loaded by the target VM which match the given signature. Multple reference types will be returned if two or more class loaders have loaded a class of the same name. The search is confined to loaded classes only; no attempt is made to load a class of the given signature.

Out Data


string					signature	JNI signature of the class to find (for example, "Ljava/lang/String;").

Reply Data


int		classes	Number of reference types that follow.
Repeated classes times:
	byte	refTypeTag	Kind of following reference type.
	referenceTypeID	typeID	Matching loaded reference type
	int	status	The current class status.

Error Data

VM_DEAD

The virtual machine is not running.

AllClasses Command (3)

Returns reference types for all classes currently loaded by the target VM.

Out Data

(None)

Reply Data


int		classes	Number of reference types that follow.
Repeated classes times:
	byte	refTypeTag	Kind of following reference type.
	referenceTypeID	typeID	Loaded reference type
	string	signature	The JNI signature of the loaded reference type
	int	status	The current class status.

Error Data

VM_DEAD

The virtual machine is not running.

AllThreads Command (4)

Returns all threads currently running in the target VM . The returned list contains threads created through java.lang.Thread, all native threads attached to the target VM through JNI, and system threads created by the target VM. Threads that have not yet been started and threads that have completed their execution are not included in the returned list.

Out Data

(None)

Reply Data


int		threads	Number of threads that follow.
Repeated threads times:
	threadID	thread	A running thread

Error Data

VM_DEAD

The virtual machine is not running.

TopLevelThreadGroups Command (5)

Returns all thread groups that do not have a parent. This command may be used as the first step in building a tree (or trees) of the existing thread groups.

Out Data

(None)

Reply Data


int		groups	Number of thread groups that follow.
Repeated groups times:
	threadGroupID	group	A top level thread group

Error Data

VM_DEAD

The virtual machine is not running.

Dispose Command (6)

Invalidates this virtual machine mirror. The communication channel to the target VM is closed, and the target VM prepares to accept another subsequent connection from this debugger or another debugger, including the following tasks:

All event requests are cancelled.
All threads suspended by the thread-level resume command or the VM-level resume command are resumed as many times as necessary for them to run.
Garbage collection is re-enabled in all cases where it was disabled

Any current method invocations executing in the target VM are continued after the disconnection. Upon completion of any such method invocation, the invoking thread continues from the location where it was originally stopped.

Resources originating in this VirtualMachine (ObjectReferences, ReferenceTypes, etc.) will become invalid.

Out Data: (None)
Reply Data: (None)
Error Data: (None)

IDSizes Command (7)

Returns the sizes of variably-sized data types in the target VM.The returned values indicate the number of bytes used by the identifiers in command and reply packets.

Out Data

(None)

Reply Data


int	fieldIDSize	fieldID size in bytes
int	methodIDSize	methodID size in bytes
int	objectIDSize	objectID size in bytes
int	referenceTypeIDSize	referenceTypeID size in bytes
int	frameIDSize	frameID size in bytes

Error Data

VM_DEAD

The virtual machine is not running.

Suspend Command (8)

Suspends the execution of the application running in the target VM. All Java threads currently running will be suspended.

Unlike java.lang.Thread.suspend, suspends of both the virtual machine and individual threads are counted. Before a thread will run again, it must be resumed through the VM-level resume command or the thread-level resume command the same number of times it has been suspended.

Out Data

(None)

Reply Data

(None)

Error Data

VM_DEAD

The virtual machine is not running.

Resume Command (9)

Resumes execution of the application after the suspend command or an event has stopped it. Suspensions of the Virtual Machine and individual threads are counted. If a particular thread is suspended n times, it must resumed n times before it will continue.

Out Data: (None)
Reply Data: (None)
Error Data: (None)

Exit Command (10)

Terminates the target VM with the given exit code. On some platforms, the exit code might be truncated, for example, to the low order 8 bits. All ids previously returned from the target VM become invalid. Threads running in the VM are abruptly terminated. A thread death exception is not thrown and finally blocks are not run.

Out Data


int					exitCode	the exit code

Reply Data

(None)

Error Data

(None)

CreateString Command (11)

Creates a new string object in the target VM and returns its id.

Out Data


string					utf	UTF-8 characters to use in the created string.

Reply Data


stringID					stringObject	Created string (instance of java.lang.String)

Error Data

VM_DEAD

The virtual machine is not running.

Capabilities Command (12)

Retrieve this VM's capabilities. The capabilities are returned as booleans, each indicating the presence or absence of a capability. The commands associated with each capability will return the NOT_IMPLEMENTED error if the cabability is not available.

Out Data

(None)

Reply Data


boolean	canWatchFieldModification	Can the VM watch field modification, and therefore can it send the Modification Watchpoint Event?
boolean	canWatchFieldAccess	Can the VM watch field access, and therefore can it send the Access Watchpoint Event?
boolean	canGetBytecodes	Can the VM get the bytecodes of a given method?
boolean	canGetSyntheticAttribute	Can the VM determine whether a field or method is synthetic? (that is, can the VM determine if the method or the field was invented by the compiler?)
boolean	canGetOwnedMonitorInfo	Can the VM get the owned monitors infornation for a thread?
boolean	canGetCurrentContendedMonitor	Can the VM get the current contended monitor of a thread?
boolean	canGetMonitorInfo	Can the VM get the monitor information for a given object?

Error Data

VM_DEAD

The virtual machine is not running.

ClassPaths Command (13)

Retrieve the classpath and bootclasspath of the target VM. If the classpath is not defined, returns an empty list. If the bootclasspath is not defined returns an empty list.

Out Data

(None)

Reply Data


string		baseDir	Base directory used to resolve relative paths in either of the following lists.
int		classpaths	Number of paths in classpath.
Repeated classpaths times:
	string	path	One component of classpath
int		bootclasspaths	Number of paths in bootclasspath.
Repeated bootclasspaths times:
	string	path	One component of bootclasspath

Error Data

VM_DEAD

The virtual machine is not running.

DisposeObjects Command (14)

Releases a list of object IDs. For each object in the list, the following applies. The count of references held by the back-end (the reference count) will be decremented by refCnt. If thereafter the reference count is less than or equal to zero, the ID is freed. Any back-end resources associated with the freed ID may be freed, and if garbage collection was disabled for the object, it will be re-enabled. The sender of this command promises that no further commands will be sent referencing a freed ID.

Use of this command is not required. If it is not sent, resources associated with each ID will be freed by the back-end at some time after the corresponding object is garbage collected. It is most useful to use this command to reduce the load on the back-end if a very large number of objects has been retrieved from the back-end (a large array, for example) but may not be garbage collected any time soon.

IDs may be re-used by the back-end after they have been freed with this command.This description assumes reference counting, a back-end may use any implementation which operates equivalently.

Out Data


int		requests	Number of object dispose requests that follow
Repeated requests times:
	objectID	object	The object ID
	int	refCnt	The number of times this object ID has been part of a packet received from the back-end. An accurate count prevents the object ID from being freed on the back-end if it is part of an incoming packet, not yet handled by the front-end.

Reply Data

(None)

Error Data

(None)

HoldEvents Command (15)

Tells the target VM to stop sending events. Events are not discarded; they are held until a subsequent ReleaseEvents command is sent. This command is useful to control the number of events sent to the debugger VM in situations where very large numbers of events are generated. While events are held by the debugger back-end, application execution may be frozen by the debugger back-end to prevent buffer overflows on the back end. Responses to commands are never held and are not affected by this command. If events are already being held, this command is ignored.

Out Data: (None)
Reply Data: (None)
Error Data: (None)

ReleaseEvents Command (16)

Tells the target VM to continue sending events. This command is used to restore normal activity after a HoldEvents command. If there is no current HoldEvents command in effect, this command is ignored.

Out Data: (None)
Reply Data: (None)
Error Data: (None)

CapabilitiesNew Command (17)

Retrieve all of this VM's capabilities. The capabilities are returned as booleans, each indicating the presence or absence of a capability. The commands associated with each capability will return the NOT_IMPLEMENTED error if the cabability is not available.Since JDWP version 1.4.

Out Data

(None)

Reply Data


boolean	canWatchFieldModification	Can the VM watch field modification, and therefore can it send the Modification Watchpoint Event?
boolean	canWatchFieldAccess	Can the VM watch field access, and therefore can it send the Access Watchpoint Event?
boolean	canGetBytecodes	Can the VM get the bytecodes of a given method?
boolean	canGetSyntheticAttribute	Can the VM determine whether a field or method is synthetic? (that is, can the VM determine if the method or the field was invented by the compiler?)
boolean	canGetOwnedMonitorInfo	Can the VM get the owned monitors infornation for a thread?
boolean	canGetCurrentContendedMonitor	Can the VM get the current contended monitor of a thread?
boolean	canGetMonitorInfo	Can the VM get the monitor information for a given object?
boolean	canRedefineClasses	Can the VM redefine classes?
boolean	canAddMethod	Can the VM add methods when redefining classes?
boolean	canUnrestrictedlyRedefineClasses	Can the VM redefine classesin arbitrary ways?
boolean	canPopFrames	Can the VM pop stack frames?
boolean	canUseInstanceFilters	Can the VM filter events by specific object?
boolean	canGetSourceDebugExtension	Can the VM get the source debug extension?
boolean	canRequestVMDeathEvent	Can the VM request VM death events?
boolean	canSetDefaultStratum	Can the VM set a default stratum?
boolean	reserved16	Reserved for future capability
boolean	reserved17	Reserved for future capability
boolean	reserved18	Reserved for future capability
boolean	reserved19	Reserved for future capability
boolean	reserved20	Reserved for future capability
boolean	reserved21	Reserved for future capability
boolean	reserved22	Reserved for future capability
boolean	reserved23	Reserved for future capability
boolean	reserved24	Reserved for future capability
boolean	reserved25	Reserved for future capability
boolean	reserved26	Reserved for future capability
boolean	reserved27	Reserved for future capability
boolean	reserved28	Reserved for future capability
boolean	reserved29	Reserved for future capability
boolean	reserved30	Reserved for future capability
boolean	reserved31	Reserved for future capability
boolean	reserved32	Reserved for future capability

Error Data

VM_DEAD

The virtual machine is not running.

RedefineClasses Command (18)

Installs new class definitions.

Out Data


int			classes	Number of reference types that follow.
Repeated classes times:
	referenceTypeID		refType	The reference type.
	int		classfile
	Repeated classfile times:
		byte	classbyte	byte in JVM class file format.

Reply Data

(None)

Error Data

INVALID_CLASS	One of the refType is not the ID of a reference type.
INVALID_OBJECT	One of the refType is not a known ID.
UNSUPPORTED_VERSION	A class file has a version number not supported by this VM.
INVALID_CLASS_FORMAT	The virtual machine attempted to read a class file and determined that the file is malformed or otherwise cannot be interpreted as a class file.
CIRCULAR_CLASS_DEFINITION	A circularity has been detected while initializing a class.
FAILS_VERIFICATION	The verifier detected that a class file, though well formed, contained some sort of internal inconsistency or security problem.
NAMES_DONT_MATCH	The class name defined in the new class file is different from the name in the old class object.
NOT_IMPLEMENTED	No aspect of this functionality is implemented (CapabilitiesNew.canRedefineClasses is false)
ADD_METHOD_NOT_IMPLEMENTED	Adding methods has not been implemented.
SCHEMA_CHANGE_NOT_IMPLEMENTED	Schema change has not been implemented.
HIERARCHY_CHANGE_NOT_IMPLEMENTED	A direct superclass is different for the new class version, or the set of directly implemented interfaces is different and canUnrestrictedlyRedefineClasses is false.
DELETE_METHOD_NOT_IMPLEMENTED	The new class version does not declare a method declared in the old class version and canUnrestrictedlyRedefineClasses is false.
CLASS_MODIFIERS_CHANGE_NOT_IMPLEMENTED	The new class version has different modifiers and and canUnrestrictedlyRedefineClasses is false.
METHOD_MODIFIERS_CHANGE_NOT_IMPLEMENTED	A method in the new class version has different modifiers than its counterpart in the old class version and and canUnrestrictedlyRedefineClasses is false.
VM_DEAD	The virtual machine is not running.

SetDefaultStratum Command (19)

Set the default stratum.

Out Data


string					stratumID	default stratum, or empty string to use reference type default.

Reply Data

(None)

Error Data

NOT_IMPLEMENTED	The functionality is not implemented in this virtual machine.
VM_DEAD	The virtual machine is not running.

ReferenceType Command Set (2)

Signature Command (1)

Returns the JNI signature of a reference type. JNI signature formats are described in the Java Native Inteface Specification

For primitive classes the returned signature is the signature of the corresponding primitive type; for example, "I" is returned as the signature of the class represented by java.lang.Integer.TYPE.

Out Data


referenceTypeID					refType	The reference type ID.

Reply Data


string					signature	The JNI signature for the reference type.

Error Data

INVALID_CLASS	refType is not the ID of a reference type.
INVALID_OBJECT	refType is not a known ID.
VM_DEAD	The virtual machine is not running.

ClassLoader Command (2)

Returns the instance of java.lang.ClassLoader which loaded a given reference type. If the reference type was loaded by the system class loader, the returned object ID is null.

Out Data


referenceTypeID					refType	The reference type ID.

Reply Data


classLoaderID					classLoader	The class loader for the reference type.

Error Data

INVALID_CLASS	refType is not the ID of a reference type.
INVALID_OBJECT	refType is not a known ID.
VM_DEAD	The virtual machine is not running.

Modifiers Command (3)

Returns the modifiers (also known as access flags) for a reference type. The returned bit mask contains information on the declaration of the reference type. If the reference type is an array or a primitive class (for example, java.lang.Integer.TYPE), the value of the returned bit mask is undefined.

Out Data


referenceTypeID					refType	The reference type ID.

Reply Data


int					modBits	Modifier bits as defined in the VM Specification

Error Data

INVALID_CLASS	refType is not the ID of a reference type.
INVALID_OBJECT	refType is not a known ID.
VM_DEAD	The virtual machine is not running.

Fields Command (4)

Returns information for each field in a reference type. Inherited fields are not included. The field list will include any synthetic fields created by the compiler. Fields are returned in the order they occur in the class file.

Out Data


referenceTypeID					refType	The reference type ID.

Reply Data


int		declared	Number of declared fields.
Repeated declared times:
	fieldID	fieldID	Field ID.
	string	name	Name of field.
	string	signature	JNI Signature of field.
	int	modBits	The modifier bit flags (also known as access flags) which provide additional information on the field declaration. Individual flag values are defined in the VM Specification.In addition, The `0xf0000000` bit identifies the field as synthetic, if the synthetic attribute capability is available.

Error Data

CLASS_NOT_PREPARED	Class has been loaded but not yet prepared.
INVALID_CLASS	refType is not the ID of a reference type.
INVALID_OBJECT	refType is not a known ID.
VM_DEAD	The virtual machine is not running.

Methods Command (5)

Returns information for each method in a reference type. Inherited methodss are not included. The list of methods will include constructors (identified with the name "<init>"), the initialization method (identified with the name "<clinit>") if present, and any synthetic methods created by the compiler. Methods are returned in the order they occur in the class file.

Out Data


referenceTypeID					refType	The reference type ID.

Reply Data


int		declared	Number of declared methods.
Repeated declared times:
	methodID	methodID	Method ID.
	string	name	Name of method.
	string	signature	JNI signature of method.
	int	modBits	The modifier bit flags (also known as access flags) which provide additional information on the method declaration. Individual flag values are defined in the VM Specification.In addition, The `0xf0000000` bit identifies the method as synthetic, if the synthetic attribute capability is available.

Error Data

CLASS_NOT_PREPARED	Class has been loaded but not yet prepared.
INVALID_CLASS	refType is not the ID of a reference type.
INVALID_OBJECT	refType is not a known ID.
VM_DEAD	The virtual machine is not running.

GetValues Command (6)

Returns the value of one or more static fields of the reference type. Each field must be member of the reference type or one of its superclasses, superinterfaces, or implemented interfaces. Access control is not enforced; for example, the values of private fields can be obtained.

Out Data


referenceTypeID		refType	The reference type ID.
int		fields	The number of values to get
Repeated fields times:
	fieldID	fieldID	A field to get

Reply Data


int		values	The number of values returned
Repeated values times:
	value	value	The field value

Error Data

INVALID_CLASS	refType is not the ID of a reference type.
INVALID_OBJECT	refType is not a known ID.
INVALID_FIELDID	Invalid field.
VM_DEAD	The virtual machine is not running.

SourceFile Command (7)

Returns the name of source file in which a reference type was declared.

Out Data


referenceTypeID					refType	The reference type ID.

Reply Data


string					sourceFile	The source file name. No path information for the file is included

Error Data

INVALID_CLASS	refType is not the ID of a reference type.
INVALID_OBJECT	refType is not a known ID.
VM_DEAD	The virtual machine is not running.

NestedTypes Command (8)

Returns the classes and interfaces directly nested within this type.Types further nested within those types are not included.

Out Data


referenceTypeID					refType	The reference type ID.

Reply Data


int		classes	The number of nested classes and interfaces
Repeated classes times:
	byte	refTypeTag	Kind of following reference type.
	referenceTypeID	typeID	The nested class or interface ID.

Error Data

INVALID_CLASS	refType is not the ID of a reference type.
INVALID_OBJECT	refType is not a known ID.
VM_DEAD	The virtual machine is not running.

Status Command (9)

Returns the current status of the reference type. The status indicates the extent to which the reference type has been initialized, as described in the VM specification. The returned status bits are undefined for array types and for primitive classes (such as java.lang.Integer.TYPE).

Out Data


referenceTypeID					refType	The reference type ID.

Reply Data


int					status	Status bits:See JDWP.ClassStatus

Error Data

INVALID_CLASS	refType is not the ID of a reference type.
INVALID_OBJECT	refType is not a known ID.
VM_DEAD	The virtual machine is not running.

Interfaces Command (10)

Returns the interfaces declared as implemented by this class. Interfaces indirectly implemented (extended by the implemented interface or implemented by a superclass) are not included.

Out Data


referenceTypeID					refType	The reference type ID.

Reply Data


int		interfaces	The number of implemented interfaces
Repeated interfaces times:
	interfaceID	interfaceType	implemented interface.

Error Data

INVALID_CLASS	refType is not the ID of a reference type.
INVALID_OBJECT	refType is not a known ID.
VM_DEAD	The virtual machine is not running.

ClassObject Command (11)

Returns the class object corresponding to this type.

Out Data


referenceTypeID					refType	The reference type ID.

Reply Data


classObjectID					classObject	class object.

Error Data

INVALID_CLASS	refType is not the ID of a reference type.
INVALID_OBJECT	refType is not a known ID.
VM_DEAD	The virtual machine is not running.

SourceDebugExtension Command (12)

Returns the value of the SourceDebugExtension attribute. Since JDWP version 1.4.

Out Data


referenceTypeID					refType	The reference type ID.

Reply Data


string					extension	extension attribute

Error Data

INVALID_CLASS	refType is not the ID of a reference type.
INVALID_OBJECT	refType is not a known ID.
ABSENT_INFORMATION	If the extension is not specified.
NOT_IMPLEMENTED	The functionality is not implemented in this virtual machine.
VM_DEAD	The virtual machine is not running.

ClassType Command Set (3)

Superclass Command (1)

Returns the immediate superclass of a class.

Out Data


classID					clazz	The class type ID.

Reply Data


classID					superclass	The superclass (null if the class ID for java.lang.Object is specified).

Error Data

INVALID_CLASS	clazz is not the ID of a class.
INVALID_OBJECT	clazz is not a known ID.
VM_DEAD	The virtual machine is not running.

SetValues Command (2)

Sets the value of one or more static fields. Each field must be member of the class type or one of its superclasses, superinterfaces, or implemented interfaces. Access control is not enforced; for example, the values of private fields can be set. Final fields cannot be set.For primitive values, the value's type must match the field's type exactly. For object values, there must exist a widening reference conversion from the value's type to the field's type and the field's type must be loaded.

Out Data


classID		clazz	The class type ID.
int		values	The number of fields to set.
Repeated values times:
	fieldID	fieldID	Field to set.
	untagged-value	value	Value to put in the field.

Reply Data

(None)

Error Data

INVALID_CLASS	clazz is not the ID of a class.
CLASS_NOT_PREPARED	Class has been loaded but not yet prepared.
INVALID_OBJECT	clazz is not a known ID or a value of an object field is not a known ID.
INVALID_FIELDID	Invalid field.
VM_DEAD	The virtual machine is not running.

InvokeMethod Command (3)

Invokes a static method. The method must be member of the class type or one of its superclasses, superinterfaces, or implemented interfaces. Access control is not enforced; for example, private methods can be invoked.

The method invocation will occur in the specified thread. Method invocation can occur only if the specified thread has been suspended by an event. Method invocation is not supported when the target VM has been suspended by the front-end.

The specified method is invoked with the arguments in the specified argument list. The method invocation is synchronous; the reply packet is not sent until the invoked method returns in the target VM. The return value (possibly the void value) is included in the reply packet. If the invoked method throws an exception, the exception object ID is set in the reply packet; otherwise, the exception object ID is null.

For primitive arguments, the argument value's type must match the argument's type exactly. For object arguments, there must exist a widening reference conversion from the argument value's type to the argument's type and the argument's type must be loaded.

By default, all threads in the target VM are resumed while the method is being invoked if they were previously suspended by an event or by command. This is done to prevent the deadlocks that will occur if any of the threads own monitors that will be needed by the invoked method. It is possible that breakpoints or other events might occur during the invocation. Note, however, that this implicit resume acts exactly like the ThreadReference resume command, so if the thread's suspend count is greater than 1, it will remain in a suspended state during the invocation. By default, when the invocation completes, all threads in the target VM are suspended, regardless their state before the invocation.

The resumption of other threads during the invoke can be prevented by specifying the INVOKE_SINGLE_THREADED bit flag in the options field; however, there is no protection against or recovery from the deadlocks described above, so this option should be used with great caution. Only the specified thread will be resumed (as described for all threads above). Upon completion of a single threaded invoke, the invoking thread will be suspended once again. Note that any threads started during the single threaded invocation will not be suspended when the invocation completes.

If the target VM is disconnected during the invoke (for example, through the VirtualMachine dispose command) the method invocation continues.

Out Data


classID		clazz	The class type ID.
threadID		thread	The thread in which to invoke.
methodID		methodID	The method to invoke.
int		arguments
Repeated arguments times:
	value	arg	The argument value.
int		options	Invocation options

Reply Data


value					returnValue	The returned value.
tagged-objectID					exception	The thrown exception.

Error Data

INVALID_CLASS	clazz is not the ID of a class.
INVALID_OBJECT	clazz is not a known ID.
INVALID_METHODID	methodID is not the ID of a method.
INVALID_THREAD	Passed thread is null, is not a valid thread or has exited.
THREAD_NOT_SUSPENDED	If the specified thread has not been suspended by an event.
VM_DEAD	The virtual machine is not running.

NewInstance Command (4)

Creates a new object of this type, invoking the specified constructor. The constructor method ID must be a member of the class type.

Instance creation will occur in the specified thread. Instance creation can occur only if the specified thread has been suspended by an event. Method invocation is not supported when the target VM has been suspended by the front-end.

The specified constructor is invoked with the arguments in the specified argument list. The constructor invocation is synchronous; the reply packet is not sent until the invoked method returns in the target VM. The return value (possibly the void value) is included in the reply packet. If the constructor throws an exception, the exception object ID is set in the reply packet; otherwise, the exception object ID is null.

If the target VM is disconnected during the invoke (for example, through the VirtualMachine dispose command) the method invocation continues.

Out Data


classID		clazz	The class type ID.
threadID		thread	The thread in which to invoke the constructor.
methodID		methodID	The constructor to invoke.
int		arguments
Repeated arguments times:
	value	arg	The argument value.
int		options	Constructor invocation options

Reply Data


tagged-objectID					newObject	The newly created object, or null if the constructor threw an exception.
tagged-objectID					exception	The thrown exception, if any; otherwise, null.

Error Data

INVALID_CLASS	clazz is not the ID of a class.
INVALID_OBJECT	clazz is not a known ID or a value of an object parameter is not a known ID..
INVALID_METHODID	methodID is not the ID of a method.
INVALID_OBJECT	If this reference type has been unloaded and garbage collected.
INVALID_THREAD	Passed thread is null, is not a valid thread or has exited.
THREAD_NOT_SUSPENDED	If the specified thread has not been suspended by an event.
VM_DEAD	The virtual machine is not running.

ArrayType Command Set (4)

NewInstance Command (1)

Creates a new array object of this type with a given length.

Out Data


arrayTypeID					arrType	The array type of the new instance.
int					length	The length of the array.

Reply Data


tagged-objectID					newArray	The newly created array object.

Error Data

INVALID_ARRAY	The array is invalid.
INVALID_OBJECT	If this reference type has been unloaded and garbage collected.
VM_DEAD	The virtual machine is not running.

InterfaceType Command Set (5)

Method Command Set (6)

LineTable Command (1)

Returns line number information for the method. The line table maps source line numbers to the initial code index of the line. The line table is ordered by code index (from lowest to highest).

Out Data


referenceTypeID					refType	The class.
methodID					methodID	The method.

Reply Data


long		start	Lowest valid code index for the method.
long		end	Highest valid code index for the method.
int		lines	The number of lines.
Repeated lines times:
	long	lineCodeIndex	Initial code index of the line (unsigned).
	int	lineNumber	Line number.

Error Data

INVALID_CLASS	refType is not the ID of a reference type.
INVALID_OBJECT	refType is not a known ID.
INVALID_METHODID	methodID is not the ID of a method.
VM_DEAD	The virtual machine is not running.

VariableTable Command (2)

Returns variable information for the method. The variable table includes arguments and locals declared within the method. For instance methods, the "this" reference is included in the table. Also, synthetic variables may be present.

Out Data


referenceTypeID					refType	The class.
methodID					methodID	The method.

Reply Data


int		argCnt	The number of words in the frame used by arguments. Eight-byte arguments use two words; all others use one.
int		slots	The number of variables.
Repeated slots times:
	long	codeIndex	First code index at which the variable is visible (unsigned). Used in conjunction with `length`. The variable can be get or set only when the current `codeIndex` <= current frame code index < `codeIndex + length`
	string	name	The variable's name.
	string	signature	The variable type's JNI signature.
	int	length	Unsigned value used in conjunction with `codeIndex`. The variable can be get or set only when the current `codeIndex` <= current frame code index < `code index + length`
	int	slot	The local variable's index in its frame

Error Data

INVALID_CLASS	refType is not the ID of a reference type.
INVALID_OBJECT	refType is not a known ID.
INVALID_METHODID	methodID is not the ID of a method.
ABSENT_INFORMATION	there is no variable information for the method.
VM_DEAD	The virtual machine is not running.

Bytecodes Command (3)

Retrieve the method's bytecodes as defined in the JVM Specification.

Out Data


referenceTypeID					refType	The class.
methodID					methodID	The method.

Reply Data


int		bytes
Repeated bytes times:
	byte	bytecode	A Java bytecode.

Error Data

INVALID_CLASS	refType is not the ID of a reference type.
INVALID_OBJECT	refType is not a known ID.
INVALID_METHODID	methodID is not the ID of a method.
NOT_IMPLEMENTED	If the target virtual machine does not support the retrieval of bytecodes.
VM_DEAD	The virtual machine is not running.

IsObsolete Command (4)

Determine if this method is obsolete.

Out Data


referenceTypeID					refType	The class.
methodID					methodID	The method.

Reply Data


boolean					isObsolete	true if this method has been replacedby a non-equivalent method usingthe RedefineClasses command

Error Data

INVALID_CLASS	refType is not the ID of a reference type.
INVALID_OBJECT	refType is not a known ID.
INVALID_METHODID	methodID is not the ID of a method.
NOT_IMPLEMENTED	If the target virtual machine does not support this query.
VM_DEAD	The virtual machine is not running.

Field Command Set (8)

ObjectReference Command Set (9)

ReferenceType Command (1)

Returns the runtime type of the object. The runtime type will be a class or an array.

Out Data


objectID					object	The object ID

Reply Data


byte					refTypeTag	Kind of following reference type.
referenceTypeID					typeID	The runtime reference type.

Error Data

INVALID_OBJECT	If this reference type has been unloaded and garbage collected.
VM_DEAD	The virtual machine is not running.

GetValues Command (2)

Returns the value of one or more instance fields. Each field must be member of the object's type or one of its superclasses, superinterfaces, or implemented interfaces. Access control is not enforced; for example, the values of private fields can be obtained.

Out Data


objectID		object	The object ID
int		fields	The number of values to get
Repeated fields times:
	fieldID	fieldID	Field to get.

Reply Data


int		values	The number of values returned
Repeated values times:
	value	value	The field value

Error Data

INVALID_OBJECT	If this reference type has been unloaded and garbage collected.
INVALID_FIELDID	Invalid field.
VM_DEAD	The virtual machine is not running.

SetValues Command (3)

Sets the value of one or more instance fields. Each field must be member of the object's type or one of its superclasses, superinterfaces, or implemented interfaces. Access control is not enforced; for example, the values of private fields can be set. For primitive values, the value's type must match the field's type exactly. For object values, there must be a widening reference conversion from the value's type to the field's type and the field's type must be loaded.

Out Data


objectID		object	The object ID
int		values	The number of fields to set.
Repeated values times:
	fieldID	fieldID	Field to set.
	untagged-value	value	Value to put in the field.

Reply Data

(None)

Error Data

INVALID_OBJECT	If this reference type has been unloaded and garbage collected.
INVALID_FIELDID	Invalid field.
VM_DEAD	The virtual machine is not running.

MonitorInfo Command (5)

Returns monitor information for an object. All threads int the VM must be suspended.

Out Data


objectID					object	The object ID

Reply Data


threadID		owner	The monitor owner, or null if it is not currently owned.
int		entryCount	The number of times the monitor has been entered.
int		waiters	The number of threads that are waiting for the monitor 0 if there is no current owner
Repeated waiters times:
	threadID	thread	A thread waiting for this monitor.

Error Data

INVALID_OBJECT	If this reference type has been unloaded and garbage collected.
NOT_IMPLEMENTED	The functionality is not implemented in this virtual machine.
VM_DEAD	The virtual machine is not running.

InvokeMethod Command (6)

Invokes a instance method. The method must be member of the object's type or one of its superclasses, superinterfaces, or implemented interfaces. Access control is not enforced; for example, private methods can be invoked.

For primitive arguments, the argument value's type must match the argument's type exactly. For object arguments, there must be a widening reference conversion from the argument value's type to the argument's type and the argument's type must be loaded.

If the target VM is disconnected during the invoke (for example, through the VirtualMachine dispose command) the method invocation continues.

Out Data


objectID		object	The object ID
threadID		thread	The thread in which to invoke.
classID		clazz	The class type.
methodID		methodID	The method to invoke.
int		arguments	The number of arguments.
Repeated arguments times:
	value	arg	The argument value.
int		options	Invocation options

Reply Data


value					returnValue	The returned value, or null if an exception is thrown.
tagged-objectID					exception	The thrown exception, if any.

Error Data

INVALID_OBJECT	If this reference type has been unloaded and garbage collected.
INVALID_CLASS	clazz is not the ID of a reference type.
INVALID_METHODID	methodID is not the ID of a method.
INVALID_THREAD	Passed thread is null, is not a valid thread or has exited.
THREAD_NOT_SUSPENDED	If the specified thread has not been suspended by an event.
VM_DEAD	The virtual machine is not running.

DisableCollection Command (7)

Prevents garbage collection for the given object. By default all objects in back-end replies may be collected at any time the target VM is running. A call to this command guarantees that the object will not be collected. The EnableCollection command can be used to allow collection once again.

Note that while the target VM is suspended, no garbage collection will occur because all threads are suspended. The typical examination of variables, fields, and arrays during the suspension is safe without explicitly disabling garbage collection.

This method should be used sparingly, as it alters the pattern of garbage collection in the target VM and, consequently, may result in application behavior under the debugger that differs from its non-debugged behavior.

Out Data


objectID					object	The object ID

Reply Data

(None)

Error Data

INVALID_OBJECT	If this reference type has been unloaded and garbage collected.
VM_DEAD	The virtual machine is not running.

EnableCollection Command (8)

Permits garbage collection for this object. By default all objects returned by the JDWP may be collected at any time the target VM is running. A call to this command is necessary only if garbage collection was previously disabled with the DisableCollection command.

Out Data


objectID					object	The object ID

Reply Data

(None)

Error Data

VM_DEAD

The virtual machine is not running.

IsCollected Command (9)

Determines whether an object has been garbage collected in the target VM.

Out Data


objectID					object	The object ID

Reply Data


boolean					isCollected	true if the object has been collected; false otherwise

Error Data

INVALID_OBJECT	If this reference type has been unloaded and garbage collected.
VM_DEAD	The virtual machine is not running.

StringReference Command Set (10)

Value Command (1)

Returns the characters contained in the string.

Out Data


objectID					stringObject	The String object ID.

Reply Data


string					stringValue	The value of the String.

Error Data

INVALID_STRING	The string is invalid.
INVALID_OBJECT	If this reference type has been unloaded and garbage collected.
VM_DEAD	The virtual machine is not running.

ThreadReference Command Set (11)

Name Command (1)

Returns the thread name.

Out Data


threadID					thread	The thread object ID.

Reply Data


string					threadName	The thread name.

Error Data

INVALID_THREAD	Passed thread is null, is not a valid thread or has exited.
INVALID_OBJECT	thread is not a known ID.
VM_DEAD	The virtual machine is not running.

Suspend Command (2)

Suspends the thread.

Unlike java.lang.Thread.suspend(), suspends of both the virtual machine and individual threads are counted. Before a thread will run again, it must be resumed the same number of times it has been suspended.

Suspending single threads with command has the same dangers java.lang.Thread.suspend(). If the suspended thread holds a monitor needed by another running thread, deadlock is possible in the target VM (at least until the suspended thread is resumed again).

The suspended thread is guaranteed to remain suspended until resumed through one of the JDI resume methods mentioned above; the application in the target VM cannot resume the suspended thread through {@link java.lang.Thread#resume}.

Note that this doesn't change the status of the thread (see the ThreadStatus command.) For example, if it was Running, it will still appear running to other threads.

Out Data


threadID					thread	The thread object ID.

Reply Data

(None)

Error Data

INVALID_THREAD	Passed thread is null, is not a valid thread or has exited.
INVALID_OBJECT	thread is not a known ID.
VM_DEAD	The virtual machine is not running.

Resume Command (3)

Resumes the execution of a given thread. If this thread was not previously suspended by the front-end, calling this command has no effect. Otherwise, the count of pending suspends on this thread is decremented. If it is decremented to 0, the thread will continue to execute.

Out Data


threadID					thread	The thread object ID.

Reply Data

(None)

Error Data

INVALID_THREAD	Passed thread is null, is not a valid thread or has exited.
INVALID_OBJECT	thread is not a known ID.
VM_DEAD	The virtual machine is not running.

Status Command (4)

Returns the current status of a thread. The thread status reply indicates the thread status the last time it was running. the suspend status provides information on the thread's suspension, if any.

Out Data


threadID					thread	The thread object ID.

Reply Data


int					threadStatus	One of the thread status codes See JDWP.ThreadStatus
int					suspendStatus	One of the suspend status codes See JDWP.SuspendStatus

Error Data

INVALID_THREAD	Passed thread is null, is not a valid thread or has exited.
INVALID_OBJECT	thread is not a known ID.
VM_DEAD	The virtual machine is not running.

ThreadGroup Command (5)

Returns the thread group that contains a given thread.

Out Data


threadID					thread	The thread object ID.

Reply Data


threadGroupID					group	The thread group of this thread.

Error Data

INVALID_THREAD	Passed thread is null, is not a valid thread or has exited.
INVALID_OBJECT	thread is not a known ID.
VM_DEAD	The virtual machine is not running.

Frames Command (6)

Returns the current call stack of a suspended thread. The sequence of frames starts with the currently executing frame, followed by its caller, and so on. The thread must be suspended, and the returned frameID is valid only while the thread is suspended.

Out Data


threadID	thread	The thread object ID.
int	startFrame	The index of the first frame to retrieve.
int	length	The count of frames to retrieve (-1 means all remaining).

Reply Data


int		frames	The number of frames retreived
Repeated frames times:
	frameID	frameID	The ID of this frame.
	location	location	The current location of this frame

Error Data

INVALID_THREAD	Passed thread is null, is not a valid thread or has exited.
INVALID_OBJECT	thread is not a known ID.
VM_DEAD	The virtual machine is not running.

FrameCount Command (7)

Returns the count of frames on this thread's stack. The thread must be suspended, and the returned count is valid only while the thread is suspended. Returns JDWP.Error.errorThreadNotSuspended if not suspended.

Out Data


threadID					thread	The thread object ID.

Reply Data


int					frameCount	The count of frames on this thread's stack.

Error Data

INVALID_THREAD	Passed thread is null, is not a valid thread or has exited.
INVALID_OBJECT	thread is not a known ID.
VM_DEAD	The virtual machine is not running.

OwnedMonitors Command (8)

Returns the objects whose monitors have been entered by this thread. The thread must be suspended, and the returned information is relevant only while the thread is suspended.

Out Data


threadID					thread	The thread object ID.

Reply Data


int		owned	The number of owned monitors
Repeated owned times:
	tagged-objectID	monitor	An owned monitor

Error Data

INVALID_THREAD	Passed thread is null, is not a valid thread or has exited.
INVALID_OBJECT	thread is not a known ID.
NOT_IMPLEMENTED	The functionality is not implemented in this virtual machine.
VM_DEAD	The virtual machine is not running.

CurrentContendedMonitor Command (9)

Returns the object, if any, for which this thread is waiting for monitor entry or with java.lang.Object.wait. The thread must be suspended, and the returned information is relevant only while the thread is suspended.

Out Data


threadID					thread	The thread object ID.

Reply Data


tagged-objectID					monitor	The contended monitor, or null if there is no current contended monitor.

Error Data

INVALID_THREAD	Passed thread is null, is not a valid thread or has exited.
INVALID_OBJECT	thread is not a known ID.
NOT_IMPLEMENTED	The functionality is not implemented in this virtual machine.
VM_DEAD	The virtual machine is not running.

Stop Command (10)

Stops the thread with an asynchronous exception, as if done by java.lang.Thread.stop

Out Data


threadID					thread	The thread object ID.
objectID					throwable	Asynchronous exception. This object must be an instance of java.lang.Throwable or a subclass

Reply Data

(None)

Error Data

INVALID_THREAD	Passed thread is null, is not a valid thread or has exited.
INVALID_OBJECT	If thread is not a known ID or the asynchronous exception has been garbage collected.
VM_DEAD	The virtual machine is not running.

Interrupt Command (11)

Interrupt the thread, as if done by java.lang.Thread.interrupt

Out Data


threadID					thread	The thread object ID.

Reply Data

(None)

Error Data

INVALID_THREAD	Passed thread is null, is not a valid thread or has exited.
INVALID_OBJECT	thread is not a known ID.
VM_DEAD	The virtual machine is not running.

SuspendCount Command (12)

Get the suspend count for this thread. The suspend count is the number of times the thread has been suspended through the thread-level or VM-level suspend commands without a corresponding resume

Out Data


threadID					thread	The thread object ID.

Reply Data


int					suspendCount	The number of outstanding suspends of this thread.

Error Data

INVALID_THREAD	Passed thread is null, is not a valid thread or has exited.
INVALID_OBJECT	thread is not a known ID.
VM_DEAD	The virtual machine is not running.

ThreadGroupReference Command Set (12)

Name Command (1)

Returns the thread group name.

Out Data


threadGroupID					group	The thread group object ID.

Reply Data


string					groupName	The thread group's name.

Error Data

INVALID_THREAD_GROUP	Thread group invalid.
INVALID_OBJECT	group is not a known ID.
VM_DEAD	The virtual machine is not running.

Parent Command (2)

Returns the thread group, if any, which contains a given thread group.

Out Data


threadGroupID					group	The thread group object ID.

Reply Data


threadGroupID					parentGroup	The parent thread group object, or null if the given thread group is a top-level thread group

Error Data

INVALID_THREAD_GROUP	Thread group invalid.
INVALID_OBJECT	group is not a known ID.
VM_DEAD	The virtual machine is not running.

Children Command (3)

Returns the threads and thread groups directly contained in this thread group. Threads and thread groups in child thread groups are not included.

Out Data


threadGroupID					group	The thread group object ID.

Reply Data


int		childThreads	The number of child threads.
Repeated childThreads times:
	threadID	childThread	A direct child thread ID.
int		childGroups	The number of child thread groups.
Repeated childGroups times:
	threadGroupID	childGroup	A direct child thread group ID.

Error Data

INVALID_THREAD_GROUP	Thread group invalid.
INVALID_OBJECT	group is not a known ID.
VM_DEAD	The virtual machine is not running.

ArrayReference Command Set (13)

Length Command (1)

Returns the number of components in a given array.

Out Data


arrayID					arrayObject	The array object ID.

Reply Data


int					arrayLength	The length of the array.

Error Data

INVALID_OBJECT	arrayObject is not a known ID.
INVALID_ARRAY	The array is invalid.
VM_DEAD	The virtual machine is not running.

GetValues Command (2)

Returns a range of array components. The specified range must be within the bounds of the array.

Out Data


arrayID	arrayObject	The array object ID.
int	firstIndex	The first index to retrieve.
int	length	The number of components to retrieve.

Reply Data


arrayregion					values	The retrieved values. If the values are objects, they are tagged-values; otherwise, they are untagged-values

Error Data

INVALID_LENGTH	If index is beyond the end of this array.
INVALID_OBJECT	arrayObject is not a known ID.
INVALID_ARRAY	The array is invalid.
VM_DEAD	The virtual machine is not running.

SetValues Command (3)

Sets a range of array components. The specified range must be within the bounds of the array. For primitive values, each value's type must match the array component type exactly. For object values, there must be a widening reference conversion from the value's type to the array component type and the array component type must be loaded.

Out Data


arrayID		arrayObject	The array object ID.
int		firstIndex	The first index to set.
int		values	The number of values to set.
Repeated values times:
	untagged-value	value	A value to set.

Reply Data

(None)

Error Data

INVALID_LENGTH	If index is beyond the end of this array.
INVALID_OBJECT	arrayObject is not a known ID.
INVALID_ARRAY	The array is invalid.
VM_DEAD	The virtual machine is not running.

ClassLoaderReference Command Set (14)

VisibleClasses Command (1)

Returns a list of all classes which this class loader has been requested to load. This class loader is considered to be an initiating class loader for each class in the returned list. The list contains each reference type defined by this loader and any types for which loading was delegated by this class loader to another class loader.

The visible class list has useful properties with respect to the type namespace. A particular type name will occur at most once in the list. Each field or variable declared with that type name in a class defined by this class loader must be resolved to that single type.

No ordering of the returned list is guaranteed.

Out Data


classLoaderID					classLoaderObject	The class loader object ID.

Reply Data


int		classes	The number of visible classes.
Repeated classes times:
	byte	refTypeTag	Kind of following reference type.
	referenceTypeID	typeID	A class visible to this class loader.

Error Data

INVALID_OBJECT	If this reference type has been unloaded and garbage collected.
INVALID_CLASS_LOADER	The class loader is invalid.
VM_DEAD	The virtual machine is not running.

EventRequest Command Set (15)

Set Command (1)

Set an event request. When the event described by this request occurs, an event is sent from the target VM.

Out Data


byte			eventKind	Event kind to request. See JDWP.EventKind for a complete list of events that can be requested.
byte			suspendPolicy	What threads are suspended when this event occurs? Note that the order of events and command replies accurately reflects the order in which threads are suspended and resumed. For example, if a VM-wide resume is processed before an event occurs which suspends the VM, the reply to the resume command will be written to the transport before the suspending event.
int			modifiers	Constraints used to control the number of generated events. Modifiers specify additional tests that an event must satisfy before it is placed in the event queue. Events are filtered by applying each modifier to an event in the order they are specified in this collection Only events that satisfy all modifiers are reported. Filtering can improve debugger performance dramatically by reducing the amount of event traffic sent from the target VM to the debugger VM.
Repeated modifiers times:
	byte		modKind	Modifier kind
	Case Count - if modKind is 1:			Limit the requested event to be reported at most once after a given number of occurrences. The event is not reported the first `count - 1` times this filter is reached. To request a one-off event, call this method with a count of 1. Once the count reaches 0, any subsequent filters in this request are applied. If none of those filters cause the event to be suppressed, the event is reported. Otherwise, the event is not reported. In either case subsequent events are never reported for this request. This modifier can be used with any event kind.
		int	count	Count before event. One for one-off.
	Case Conditional - if modKind is 2:			Conditional on expression
		int	exprID	For the future
	Case ThreadOnly - if modKind is 3:			Restricts reported events to those in the given thread. This modifier can be used with any event kind except for class unload.
		threadID	thread	Required thread
	Case ClassOnly - if modKind is 4:			For class prepare events, restricts the events generated by this request to be the preparation of the given reference type and any subtypes. For other events, restricts the events generated by this request to those whose location is in the given reference type or any of its subtypes. An event will be generated for any location in a reference type that can be safely cast to the given reference type. This modifier can be used with any event kind except class unload, thread start, and thread end.
		referenceTypeID	clazz	Required class
	Case ClassMatch - if modKind is 5:			Restricts reported events to those for classes whose name matches the given restricted regular expression. For class prepare events, the prepared class name is matched. For class unload events, the unloaded class name is matched. For other events, the class name of the event's location is matched. This modifier can be used with any event kind except thread start and thread end.
		string	classPattern	Required class pattern. Matches are limited to exact matches of the given class pattern and matches of patterns that begin or end with ''; for example, ".Foo" or "java.*".
	Case ClassExclude - if modKind is 6:			Restricts reported events to those for classes whose name does not match the given restricted regular expression. For class prepare events, the prepared class name is matched. For class unload events, the unloaded class name is matched. For other events, the class name of the event's location is matched. This modifier can be used with any event kind except thread start and thread end.
		string	classPattern	Disallowed class pattern. Matches are limited to exact matches of the given class pattern and matches of patterns that begin or end with ''; for example, ".Foo" or "java.*".
	Case LocationOnly - if modKind is 7:			Restricts reported events to those that occur at the given location. This modifier can be used with breakpoint, field access, field modification, step, and exception event kinds.
		location	loc	Required location
	Case ExceptionOnly - if modKind is 8:			Restricts reported exceptions by their class and whether they are caught or uncaught. This modifier can be used with exception event kinds only.
		referenceTypeID	exceptionOrNull	Exception to report. Null (0) means report exceptions of all types. A non-null type restricts the reported exception events to exceptions of the given type or any of its subtypes.
		boolean	caught	Report caught exceptions
		boolean	uncaught	Report uncaught exceptions. Note that it is not always possible to determine whether an exception is caught or uncaught at the time it is thrown. See the exception event catch location under composite events for more information.
	Case FieldOnly - if modKind is 9:			Restricts reported events to those that occur for a given field. This modifier can be used with field access and field modification event kinds only.
		referenceTypeID	declaring	Type in which field is declared.
		fieldID	fieldID	Required field
	Case Step - if modKind is 10:			Restricts reported step events to those which satisfy depth and size constraints. This modifier can be used with step event kinds only.
		threadID	thread	Thread in which to step
		int	size	size of each step. See JDWP.StepSize
		int	depth	relative call stack limit. See JDWP.StepDepth
	Case InstanceOnly - if modKind is 11:			Restricts reported events to those whose active 'this' object is the given object. Match value is the null object for static methods. This modifier can be used with any event kind except class prepare, class unload, thread start, and thread end. Introduced in JDWP version 1.4.
		objectID	instance	Required 'this' object

Reply Data


int					requestID	ID of created request

Error Data

INVALID_THREAD	Passed thread is null, is not a valid thread or has exited.
INVALID_CLASS	Invalid class.
INVALID_STRING	The string is invalid.
INVALID_OBJECT	If this reference type has been unloaded and garbage collected.
INVALID_COUNT	The count is invalid.
INVALID_FIELDID	Invalid field.
INVALID_METHODID	Invalid method.
INVALID_LOCATION	Invalid location.
INVALID_EVENT_TYPE	The specified event type id is not recognized.
NOT_IMPLEMENTED	The functionality is not implemented in this virtual machine.
VM_DEAD	The virtual machine is not running.

Clear Command (2)

Clear an event request.

Out Data


byte					event	Event type to clear
int					requestID	ID of request to clear

Reply Data

(None)

Error Data

VM_DEAD

The virtual machine is not running.

ClearAllBreakpoints Command (3)

Removes all set breakpoints.

Out Data

(None)

Reply Data

(None)

Error Data

VM_DEAD

The virtual machine is not running.

StackFrame Command Set (16)

GetValues Command (1)

Returns the value of one or more local variables in a given frame. Each variable must be visible at the frame's code index. Even if local variable information is not available, values can be retrieved if the front-end is able to determine the correct local variable index. (Typically, this index can be determined for method arguments from the method signature without access to the local variable table information.)

Out Data


threadID		thread	The frame's thread.
frameID		frame	The frame ID.
int		slots	The number of values to get.
Repeated slots times:
	int	slot	The local variable's index in the frame.
	byte	sigbyte	A tag identifying the type of the variable

Reply Data


int		values	The number of values retrieved.
Repeated values times:
	value	slotValue	The value of the local variable.

Error Data

INVALID_THREAD	Passed thread is null, is not a valid thread or has exited.
INVALID_OBJECT	If this reference type has been unloaded and garbage collected.
INVALID_FRAMEID	Invalid jframeID.
VM_DEAD	The virtual machine is not running.

SetValues Command (2)

Sets the value of one or more local variables. Each variable must be visible at the current frame code index. For primitive values, the value's type must match the variable's type exactly. For object values, there must be a widening reference conversion from the value's type to the variable's type and the variable's type must be loaded.

Even if local variable information is not available, values can be set, if the front-end is able to determine the correct local variable index. (Typically, this index can be determined for method arguments from the method signature without access to the local variable table information.)

Out Data


threadID		thread	The frame's thread.
frameID		frame	The frame ID.
int		slotValues	The number of values to set.
Repeated slotValues times:
	int	slot	The slot ID.
	value	slotValue	The value to set.

Reply Data

(None)

Error Data

INVALID_THREAD	Passed thread is null, is not a valid thread or has exited.
INVALID_OBJECT	If this reference type has been unloaded and garbage collected.
INVALID_FRAMEID	Invalid jframeID.
VM_DEAD	The virtual machine is not running.

ThisObject Command (3)

Returns the value of the 'this' reference for this frame. If the frame's method is static or native, the reply will contain the null object reference.

Out Data


threadID					thread	The frame's thread.
frameID					frame	The frame ID.

Reply Data


tagged-objectID					objectThis	The 'this' object for this frame.

Error Data

INVALID_THREAD	Passed thread is null, is not a valid thread or has exited.
INVALID_OBJECT	If this reference type has been unloaded and garbage collected.
INVALID_FRAMEID	Invalid jframeID.
VM_DEAD	The virtual machine is not running.

PopFrames Command (4)

Pop stack frames, thru and including 'frame'.Since JDWP version 1.4.

Out Data


threadID					thread	The thread object ID.
frameID					frame	The frame ID.

Reply Data

(None)

Error Data

INVALID_THREAD	Passed thread is null, is not a valid thread or has exited.
INVALID_OBJECT	thread is not a known ID.
INVALID_FRAMEID	Invalid jframeID.
THREAD_NOT_SUSPENDED	If the specified thread has not been suspended by an event.
NO_MORE_FRAMES	There are no more Java or JNI frames on the call stack.
INVALID_FRAMEID	Invalid jframeID.
NOT_IMPLEMENTED	The functionality is not implemented in this virtual machine.
VM_DEAD	The virtual machine is not running.

ClassObjectReference Command Set (17)

ReflectedType Command (1)

Returns the reference type reflected by this class object.

Out Data


classObjectID					classObject	The class object.

Reply Data


byte					refTypeTag	Kind of following reference type.
referenceTypeID					typeID	reflected reference type

Error Data

INVALID_OBJECT	If this reference type has been unloaded and garbage collected.
VM_DEAD	The virtual machine is not running.

Event Command Set (64)

Composite Command (100)

Several events may occur at a given time in the target VM. For example, there may be more than one breakpoint request for a given location or you might single step to the same location as a breakpoint request. These events are delivered together as a composite event. For uniformity, a composite event is always used to deliver events, even if there is only one event to report.

The events that are grouped in a composite event are restricted in the following ways:

Always singleton composite events:
- VM Start Event
- VM Death Event
Only with other thread start events for the same thread:
- Thread Start Event
Only with other thread death events for the same thread:
- Thread Death Event
Only with other class prepare events for the same class:
- Class Prepare Event}
Only with other class unload events for the same class:
- Class Unload Event
Only with other access watchpoint events for the same field access:
- Access Watchpoint Event
Only with other modification watchpoint events for the same field modification:
- Modification Watchpoint Event
Only with other ExceptionEvents for the same exception occurrance:
- ExceptionEvent
Only with other members of this group, at the same location and in the same thread:
- Breakpoint Event
- Step Event
- Method Entry Event
- Method Exit Event

Event Data


byte			suspendPolicy	Which threads where suspended by this composite event?
int			events	Events in set.
Repeated events times:
	byte		eventKind	Event kind selector
	Case VMStart - if eventKind is JDWP.EventKind.VM_START:			Notification of initialization of a target VM. This event is received before the main thread is started and before any application code has been executed. Before this event occurs a significant amount of system code has executed and a number of system classes have been loaded. This event is always generated by the target VM, even if not explicitly requested.
		int	requestID	Request that generated event (or 0 if this event is automatically generated.
		threadID	thread	Initial thread
	Case SingleStep - if eventKind is JDWP.EventKind.SINGLE_STEP:			Notification of step completion in the target VM. The step event is generated before the code at its location is executed.
		int	requestID	Request that generated event
		threadID	thread	Stepped thread
		location	location	Location stepped to
	Case Breakpoint - if eventKind is JDWP.EventKind.BREAKPOINT:			Notification of a breakpoint in the target VM. The breakpoint event is generated before the code at its location is executed.
		int	requestID	Request that generated event
		threadID	thread	thread which hit breakpoint
		location	location	Location hit
	Case MethodEntry - if eventKind is JDWP.EventKind.METHOD_ENTRY:			Notification of a method invocation in the target VM. This event is generated before any code in the invoked method has executed. Method entry events are generated for both native and non-native methods. In some VMs method entry events can occur for a particular thread before its thread start event occurs if methods are called as part of the thread's initialization.
		int	requestID	Request that generated event
		threadID	thread	thread which entered method
		location	location	Location of entry
	Case MethodExit - if eventKind is JDWP.EventKind.METHOD_EXIT:			Notification of a method return in the target VM. This event is generated after all code in the method has executed, but the location of this event is the last executed location in the method. Method exit events are generated for both native and non-native methods. Method exit events are not generated if the method terminates with a thrown exception.
		int	requestID	Request that generated event
		threadID	thread	thread which exited method
		location	location	Location of exit
	Case Exception - if eventKind is JDWP.EventKind.EXCEPTION:			Notification of an exception in the target VM. If the exception is thrown from a non-native method, the exception event is generated at the location where the exception is thrown. If the exception is thrown from a native method, the exception event is generated at the first non-native location reached after the exception is thrown.
		int	requestID	Request that generated event
		threadID	thread	Thread with exception
		location	location	Location of exception throw (or first non-native location after throw if thrown from a native method)
		tagged-objectID	exception	Thrown exception
		location	catchLocation	Location of catch, or 0 if not caught. An exception is considered to be caught if, at the point of the throw, the current location is dynamically enclosed in a try statement that handles the exception. (See the JVM specification for details). If there is such a try statement, the catch location is the first location in the appropriate catch clause. If there are native methods in the call stack at the time of the exception, there are important restrictions to note about the returned catch location. In such cases, it is not possible to predict whether an exception will be handled by some native method on the call stack. Thus, it is possible that exceptions considered uncaught here will, in fact, be handled by a native method and not cause termination of the target VM. Furthermore, it cannot be assumed that the catch location returned here will ever be reached by the throwing thread. If there is a native frame between the current location and the catch location, the exception might be handled and cleared in that native method instead. Note that compilers can generate try-catch blocks in some cases where they are not explicit in the source code; for example, the code generated for `synchronized` and `finally` blocks can contain implicit try-catch blocks. If such an implicitly generated try-catch is present on the call stack at the time of the throw, the exception will be considered caught even though it appears to be uncaught from examination of the source code.
	Case ThreadStart - if eventKind is JDWP.EventKind.THREAD_START:			Notification of a new running thread in the target VM. The new thread can be the result of a call to `java.lang.Thread.start` or the result of attaching a new thread to the VM though JNI. The notification is generated by the new thread some time before its execution starts. Because of this timing, it is possible to receive other events for the thread before this event is received. (Notably, Method Entry Events and Method Exit Events might occur during thread initialization. It is also possible for the VirtualMachine AllThreads command to return a thread before its thread start event is received. Note that this event gives no information about the creation of the thread object which may have happened much earlier, depending on the VM being debugged.
		int	requestID	Request that generated event
		threadID	thread	Started thread
	Case ThreadDeath - if eventKind is JDWP.EventKind.THREAD_DEATH:			Notification of a completed thread in the target VM. The notification is generated by the dying thread before it terminates. Because of this timing, it is possible for {@link VirtualMachine#allThreads} to return this thread after this event is received. Note that this event gives no information about the lifetime of the thread object. It may or may not be collected soon depending on what references exist in the target VM.
		int	requestID	Request that generated event
		threadID	thread	Ending thread
	Case ClassPrepare - if eventKind is JDWP.EventKind.CLASS_PREPARE:			Notification of a class prepare in the target VM. See the JVM specification for a definition of class preparation. Class prepare events are not generated for primtiive classes (for example, java.lang.Integer.TYPE).
		int	requestID	Request that generated event
		threadID	thread	Preparing thread. In rare cases, this event may occur in a debugger system thread within the target VM. Debugger threads take precautions to prevent these events, but they cannot be avoided under some conditions, especially for some subclasses of java.lang.Error. If the event was generated by a debugger system thread, the value returned by this method is null, and if the requested suspend policy for the event was EVENT_THREAD all threads will be suspended instead, and the composite event's suspend policy will reflect this change. Note that the discussion above does not apply to system threads created by the target VM during its normal (non-debug) operation.
		byte	refTypeTag	Kind of reference type. See JDWP.TypeTag
		referenceTypeID	typeID	Type being prepared
		string	signature	Type signature
		int	status	Status of type. See JDWP.ClassStatus
	Case ClassUnload - if eventKind is JDWP.EventKind.CLASS_UNLOAD:			Notification of a class unload in the target VM. There are severe constraints on the debugger back-end during garbage collection, so unload information is greatly limited.
		int	requestID	Request that generated event
		string	signature	Type signature
	Case FieldAccess - if eventKind is JDWP.EventKind.FIELD_ACCESS:			Notification of a field access in the target VM. Field modifications are not considered field accesses.
		int	requestID	Request that generated event
		threadID	thread	Accessing thread
		location	location	Location of access
		byte	refTypeTag	Kind of reference type. See JDWP.TypeTag
		referenceTypeID	typeID	Type of field
		fieldID	fieldID	Field being accessed
		tagged-objectID	object	Object being accessed (null=0 for statics
	Case FieldModification - if eventKind is JDWP.EventKind.FIELD_MODIFICATION:			Notification of a field modification in the target VM.
		int	requestID	Request that generated event
		threadID	thread	Modifying thread
		location	location	Location of modify
		byte	refTypeTag	Kind of reference type. See JDWP.TypeTag
		referenceTypeID	typeID	Type of field
		fieldID	fieldID	Field being modified
		tagged-objectID	object	Object being modified (null=0 for statics
		value	valueToBe	Value to be assigned
	Case VMDeath - if eventKind is JDWP.EventKind.VM_DEATH:
		int	requestID	Request that generated event

Error Constants


NONE	0	No error has occurred.
INVALID_THREAD	10	Passed thread is null, is not a valid thread or has exited.
INVALID_THREAD_GROUP	11	Thread group invalid.
INVALID_PRIORITY	12	Invalid priority.
THREAD_NOT_SUSPENDED	13	If the specified thread has not been suspended by an event.
THREAD_SUSPENDED	14	Thread already suspended.
INVALID_OBJECT	20	If this reference type has been unloaded and garbage collected.
INVALID_CLASS	21	Invalid class.
CLASS_NOT_PREPARED	22	Class has been loaded but not yet prepared.
INVALID_METHODID	23	Invalid method.
INVALID_LOCATION	24	Invalid location.
INVALID_FIELDID	25	Invalid field.
INVALID_FRAMEID	30	Invalid jframeID.
NO_MORE_FRAMES	31	There are no more Java or JNI frames on the call stack.
OPAQUE_FRAME	32	Information about the frame is not available.
NOT_CURRENT_FRAME	33	Operation can only be performed on current frame.
TYPE_MISMATCH	34	The variable is not an appropriate type for the function used.
INVALID_SLOT	35	Invalid slot.
DUPLICATE	40	Item already set.
NOT_FOUND	41	Desired element not found.
INVALID_MONITOR	50	Invalid monitor.
NOT_MONITOR_OWNER	51	This thread doesn't own the monitor.
INTERRUPT	52	The call has been interrupted before completion.
INVALID_CLASS_FORMAT	60	The virtual machine attempted to read a class file and determined that the file is malformed or otherwise cannot be interpreted as a class file.
CIRCULAR_CLASS_DEFINITION	61	A circularity has been detected while initializing a class.
FAILS_VERIFICATION	62	The verifier detected that a class file, though well formed, contained some sort of internal inconsistency or security problem.
ADD_METHOD_NOT_IMPLEMENTED	63	Adding methods has not been implemented.
SCHEMA_CHANGE_NOT_IMPLEMENTED	64	Schema change has not been implemented.
INVALID_TYPESTATE	65	The state of the thread has been modified, and is now inconsistent.
HIERARCHY_CHANGE_NOT_IMPLEMENTED	66	A direct superclass is different for the new class version, or the set of directly implemented interfaces is different and canUnrestrictedlyRedefineClasses is false.
DELETE_METHOD_NOT_IMPLEMENTED	67	The new class version does not declare a method declared in the old class version and canUnrestrictedlyRedefineClasses is false.
UNSUPPORTED_VERSION	68	A class file has a version number not supported by this VM.
NAMES_DONT_MATCH	69	The class name defined in the new class file is different from the name in the old class object.
CLASS_MODIFIERS_CHANGE_NOT_IMPLEMENTED	70	The new class version has different modifiers and and canUnrestrictedlyRedefineClasses is false.
METHOD_MODIFIERS_CHANGE_NOT_IMPLEMENTED	71	A method in the new class version has different modifiers than its counterpart in the old class version and and canUnrestrictedlyRedefineClasses is false.
NOT_IMPLEMENTED	99	The functionality is not implemented in this virtual machine.
NULL_POINTER	100	Invalid pointer.
ABSENT_INFORMATION	101	Desired information is not available.
INVALID_EVENT_TYPE	102	The specified event type id is not recognized.
ILLEGAL_ARGUMENT	103	Illegal argument.
OUT_OF_MEMORY	110	The function needed to allocate memory and no more memory was available for allocation.
ACCESS_DENIED	111	Debugging has not been enabled in this virtual machine. JVMDI cannot be used.
VM_DEAD	112	The virtual machine is not running.
INTERNAL	113	An unexpected internal error has occurred.
UNATTACHED_THREAD	115	The thread being used to call this function is not attached to the virtual machine. Calls must be made from attached threads.
INVALID_TAG	500	object type id or class tag.
ALREADY_INVOKING	502	Previous invoke not complete.
INVALID_INDEX	503	Index is invalid.
INVALID_LENGTH	504	The length is invalid.
INVALID_STRING	506	The string is invalid.
INVALID_CLASS_LOADER	507	The class loader is invalid.
INVALID_ARRAY	508	The array is invalid.
TRANSPORT_LOAD	509	Unable to load the transport.
TRANSPORT_INIT	510	Unable to initialize the transport.
NATIVE_METHOD	511
INVALID_COUNT	512	The count is invalid.

EventKind Constants


VM_DISCONNECTED	100	Never sent across JDWP
VM_START	JDWP.EventKind.VM_INIT
THREAD_DEATH	JDWP.EventKind.THREAD_END
SINGLE_STEP	1
BREAKPOINT	2
FRAME_POP	3
EXCEPTION	4
USER_DEFINED	5
THREAD_START	6
THREAD_END	7
CLASS_PREPARE	8
CLASS_UNLOAD	9
CLASS_LOAD	10
FIELD_ACCESS	20
FIELD_MODIFICATION	21
EXCEPTION_CATCH	30
METHOD_ENTRY	40
METHOD_EXIT	41
VM_INIT	90
VM_DEATH	99

ThreadStatus Constants


ZOMBIE	0
RUNNING	1
SLEEPING	2
MONITOR	3
WAIT	4

SuspendStatus Constants


SUSPEND_STATUS_SUSPENDED	0x1

ClassStatus Constants


VERIFIED	1
PREPARED	2
INITIALIZED	4
ERROR	8

TypeTag Constants


CLASS	1	ReferenceType is a class.
INTERFACE	2	ReferenceType is an interface.
ARRAY	3	ReferenceType is an array.

Tag Constants


ARRAY	91	'[' - an array object (objectID size).
BYTE	66	'B' - a byte value (1 byte).
CHAR	67	'C' - a character value (2 bytes).
OBJECT	76	'L' - an object (objectID size).
FLOAT	70	'F' - a float value (4 bytes).
DOUBLE	68	'D' - a double value (8 bytes).
INT	73	'I' - an int value (4 bytes).
LONG	74	'J' - a long value (8 bytes).
SHORT	83	'S' - a short value (2 bytes).
VOID	86	'V' - a void value (no bytes).
BOOLEAN	90	'Z' - a boolean value (1 byte).
STRING	115	's' - a String object (objectID size).
THREAD	116	't' - a Thread object (objectID size).
THREAD_GROUP	103	'g' - a ThreadGroup object (objectID size).
CLASS_LOADER	108	'l' - a ClassLoader object (objectID size).
CLASS_OBJECT	99	'c' - a class object object (objectID size).

StepDepth Constants


INTO	0	Step into any method calls that occur before the end of the step.
OVER	1	Step over any method calls that occur before the end of the step.
OUT	2	Step out of the current method.

StepSize Constants


MIN	0	Step by the minimum possible amount (often a bytecode instruction).
LINE	1	Step to the next source line unless there is no line number information in which case a MIN step is done instead.

SuspendPolicy Constants


NONE	0	Suspend no threads when this event is encountered.
EVENT_THREAD	1	Suspend the event thread when this event is encountered.
ALL	2	Suspend all threads when this event is encountered.

InvokeOptions Constants


INVOKE_SINGLE_THREADED	0x01	otherwise, all threads started.
INVOKE_NONVIRTUAL	0x02	otherwise, normal virtual invoke (instance methods only)

Please send comments to: java-debugger@java.sun.com

JavaTM Debug Wire Protocol Specification Details

VirtualMachine Command Set (1)

Version Command (1)

ClassesBySignature Command (2)

AllClasses Command (3)

AllThreads Command (4)

TopLevelThreadGroups Command (5)

Dispose Command (6)

IDSizes Command (7)

Suspend Command (8)

Resume Command (9)

Exit Command (10)

CreateString Command (11)

Capabilities Command (12)

ClassPaths Command (13)

DisposeObjects Command (14)

HoldEvents Command (15)

ReleaseEvents Command (16)

CapabilitiesNew Command (17)

RedefineClasses Command (18)

SetDefaultStratum Command (19)

ReferenceType Command Set (2)

Signature Command (1)

ClassLoader Command (2)

Modifiers Command (3)

Fields Command (4)

Methods Command (5)

GetValues Command (6)

SourceFile Command (7)

NestedTypes Command (8)

Status Command (9)

Interfaces Command (10)

ClassObject Command (11)

SourceDebugExtension Command (12)

ClassType Command Set (3)

Superclass Command (1)

SetValues Command (2)

InvokeMethod Command (3)

NewInstance Command (4)

ArrayType Command Set (4)

NewInstance Command (1)

InterfaceType Command Set (5)

Method Command Set (6)

LineTable Command (1)

VariableTable Command (2)

Bytecodes Command (3)

IsObsolete Command (4)

Field Command Set (8)

ObjectReference Command Set (9)

ReferenceType Command (1)

GetValues Command (2)

SetValues Command (3)

MonitorInfo Command (5)

InvokeMethod Command (6)

DisableCollection Command (7)

EnableCollection Command (8)

IsCollected Command (9)

StringReference Command Set (10)

Value Command (1)

ThreadReference Command Set (11)

Name Command (1)

Suspend Command (2)

Resume Command (3)

Status Command (4)

ThreadGroup Command (5)

Frames Command (6)

FrameCount Command (7)

OwnedMonitors Command (8)

CurrentContendedMonitor Command (9)

Stop Command (10)

Interrupt Command (11)

SuspendCount Command (12)

ThreadGroupReference Command Set (12)

Name Command (1)

Parent Command (2)

Children Command (3)

ArrayReference Command Set (13)

Length Command (1)

GetValues Command (2)

SetValues Command (3)

Java^TM Debug Wire Protocol
Specification Details