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FB Informatik

(C) AG DBIS

Verification of Protocol taDOM2

For the taDOM2 locking protocol the following locks are used:

	Lock on Context Node	Lock on Parent Node	Description
	IR	IR	Intention read: At least one descendant of the context node has been read.
	NR	IR	Node read: The context node has been read.
	LR	IR	Level read: The context node and all its child nodes have been read.
	SR	IR	Subtree read: The context node and all its descendants have been read.
	IX	IX	Intention exclusive: At least one descendant node (but not a child node) of the context node has been modified.
	CX	IX	Child exclusive: At least on child node of the context node has been modified.
	SU	IR	Subtree update: The context node and all its descendant nodes have been read. Possible downgrade to SR or upgrade to SX.
	SX	CX	Subtree exclusive: The context node and all its descendants are locked for deletion.

Lock Compatibility Matrix:

	-	IR	NR	LR	SR	IX	CX	SU	SX
IR	+	+	+	+	+	+	+	-	-
NR	+	+	+	+	+	+	+	-	-
LR	+	+	+	+	+	+	-	-	-
SR	+	+	+	+	+	-	-	-	-
IX	+	+	+	+	-	+	+	-	-
CX	+	+	+	-	-	+	+	-	-
SU	+	+	+	+	+	-	-	-	-
SX	+	-	-	-	-	-	-	-	-

Compatibility matrix for taDOM2

Check of Compatibility Matrix: Ok

Lock Conversion Matrix:

Lock Strength-Relationships:

	IR	is stronger than	NR
	NR	is stronger than	IR
	LR	is stronger than	IR, NR
	SR	is stronger than	IR, NR, LR
	IX	is stronger than	IR, NR
	CX	is stronger than	IR, NR, IX
	SU	is stronger than	IR, NR, LR, SR, IX, CX, SX
	SX	is stronger than	IR, NR, LR, SR, IX, CX, SU

	-	IR	NR	LR	SR	IX	CX	SU	SX
IR	IR	IR	NR	LR	SR	IX	CX	SU	SX
NR	NR	NR	NR	LR	SR	IX	CX	SU	SX
LR	LR	LR	LR	LR	SR	IX_NR	CX_NR	SU	SX
SR	SR	SR	SR	SR	SR	IX_SR	CX_SR	SR	SX
IX	IX	IX	IX	IX_NR	IX_SR	IX	CX	SX	SX
CX	CX	CX	CX	CX_NR	CX_SR	CX	CX	SX	SX
SU	SU	SU	SU	SU	SU	SX	SX	SU	SX
SX	SX	SX	SX	SX	SX	SX	SX	SX	SX

Conversion matrix for taDOM2

Check of Conversion Matrix: Ok