A repository may support simple versioning or full versioning. This section describes the syntax and behavior of the Java API for both types of versioning. Details on the underlying concepts, data structures and node types can be found in §3.13 Versioning Model.
Whether an implementation supports simple versioning can be determined by querying the repository descriptor table with
Whether it supports full versioning can be determined by querying
A return value of true indicates support (see §24.2 Repository Descriptors).
A new versionable node is created by assigning it the appropriate mixin type: mix:simpleVersionable under simple versioning or mix:versionable under full versioning. This may be done either to an existing node, through a Node.addMixin or at node creation, through assignment of a primary type that inherits from the mixin. Some repositories may also automatically assign a versionable mixin on creation of certain nodes (see §3.7.6 Node Type Inheritance and §10.10 Node Type Assignment).
Under both simple and full versioning, on persist of a new versionable node N that neither corresponds nor shares with an existing node:
The jcr:isCheckedOut property of N is set to true and
A new VersionHistory (H) is created for N. H contains one Version, the root version (V0) (see §220.127.116.11 Root Version).
Additionally, under full versioning:
A new nt:versionHistory node is created and bound to the VersionHistory object H .
The jcr:versionableUuid property of H is set to the identifier of N.
If N is the result of a copy operation then the jcr:copiedFrom property of H is set as described in §15.1.4 Copying Versionable Nodes and Version Lineage. Otherwise this property is not added.
A new nt:versionLabels node (L) is created as the jcr:versionLabels child node of H.
A new nt:version node is created and bound to V0. This node becomes the jcr:rootVersion child node of H.
A new nt:frozenNode node (F) is created as the jcr:frozenNode child node of V0. F does not hold any state information about N except the node type and identifier information found in jcr:frozenPrimaryType, jcr:frozenMixinTypes, and jcr:frozenUuid properties (see §3.13.4 Frozen Nodes).
The REFERENCE property jcr:versionHistory of N is initialized to the identifier of H. This constitutes a reference from N to its version history.
The REFERENCE property jcr:baseVersion of N is initialized to the identifier of V0. This constitutes a reference from N to its current base version.
The multi-value REFERENCE property jcr:predecessors of N is initialized to contain a single identifier, that of V0 (the same as jcr:baseVersion).
The version history of a versionable node is represented by a VersionHistory object acquired through
where absPath is the absolute path to the node.
Conversely, given a VersionHistory, the versionable node to which it belongs can be found through
which returns the identifier of the versionable node, which can then be used to get the node itself (see §5.1.4 Getting a Node by Identifier).
The root version of a version history is accessed through
Under full versioning the root version can also be accessed through a Node.getNode or an equivalent standard content access method, since it also exists as an nt:version child node of the nt:versionHistory node, called jcr:rootVersion.
The full set of versions within a version history can be retrieved through
If the version graph of this history is linear then the versions are returned in order of creation date, from oldest to newest. Otherwise the order of the returned versions is implementation-dependent.
Alternatively, the method
returns an iterator over all the versions in the line of descent from the root version to the base version that is bound to the workspace through which this VersionHistory was acquired.
Within a version history H, B is the base version bound to workspace W if and only if there exists a versionable node N in W whose version history is H and B is the base version of N.
The line of descent from version V1 to V2, where V2 is an eventual successor of V1, is the ordered list of versions starting with V1 and proceeding through each direct successor to V2.
The versions are returned in order of creation date, from oldest to newest.
Note that in a simple versioning repository the behavior of this method is equivalent to returning all versions in the version history in order from oldest to newest.
Versions can also be retrieved directly by name, using
Version VersionHistory.getVersion(String versionName),
or by label, using,
Version VersionHistory.getVersionByLabel(String label)
(see §15.4 Version Labels).
The frozen nodes within each of the versions within the history can be accessed directly from the VersionHistory through
NodeIterator VersionHistory.getAllFrozenNodes() and
These methods return the frozen nodes within the version history corresponding to, and in the same order as, the Version objects returned by VersionHistory.getAllVersions and VersionHistory.getAllLinearVersions, respectively.
The VersionHistory interface extends Node. Under simple versioning version histories are not represented by nodes in content, so the methods inherited from Node are not required to function and may instead throw a RepositoryException. Under full versioning the VersionHistory object represents the corresponding nt:versionHistory node and its Node methods must function accordingly.
Version VersionManager.getBaseVersion(String absPath)
returns the current base version of the versionable node at absPath.
When an existing versionable node is moved to a new location with Workspace.move or Session.move, it maintains the same version history and no changes are made to that history.
Under both simple and full versioning, when an existing versionable node N is copied to a new location either in the same workspace or another, and the repository preserves the versionable mixin (see §10.7.4 Dropping Mixins on Copy):
A copy of N, call it M, is created, as usual.
A new, empty, version history for M, call it HM, is also created.
Under full versioning:
The properties jcr:versionHistory, jcr:baseVersion and jcr:predecessors of M are not copied from N but are initialized as usual.
The jcr:copiedFrom property of HM is set to point to the base version of N.
The jcr:copiedFrom property allows an application to determine the lineage of a version across version histories that were produced by copying a versionable node to a new location.
Under both simple and full versioning, when a versionable node N is cloned to another workspace:
A clone of N, call it N’, is created, as usual.
N’ is initialized to have the same version history and base version as N.
Under full versioning:
The jcr:versionHistory, jcr:baseVersion and jcr:predecessors properties of N are copied to N’ unchanged.
Under both simple and full versioning, when a new node N’ is added to the shared set of a shareable, versionable node N:
The shared node N’ is created, as usual.
N’ is initialized to have the same version history and base version as N. Unlike in the case of cloning (see §15.1.5 Cloning Versionable Nodes) the base versions of N and N’ will always remain identical.
Under full versioning:
Because nodes in the same shared set have identical properties, mix:versionable nodes in the same shared set will necessarily have identical jcr:versionHistory, jcr:baseVersion and jcr:predecessors properties.
A new version of a versionable node is created using
Version VersionManager.checkin(String absPath)
where absPath is the absolute path of the node.
On check-in of a versionable node N with version history H:
If N is not mix:simpleVersionable or mix:versionable, an UnsupportedRepositoryOperationException is thrown, otherwise,
if N has unsaved changes pending, an InvalidItemStateException is thrown, otherwise,
if N is already checked-in, this method has no effect and returns the base version (see §18.104.22.168 Base Version) of N, otherwise,
if N has a jcr:mergeFailed property present, a VersionException is thrown (notice that this is enforced in any case due to the ABORT setting of the jcr:mergeFailed property's OnParentVersion attribute).
The subgraph rooted at N is made read-only (see §15.2.2 Read-Only on Check-In).
A new Version, V, is created with a system-determined version name (see §22.214.171.124 Version Name) and a created date (see §126.96.36.199 Created Date) as part of its state. Under full versioning, a new nt:version node is bound to V and added as a child node of H, with the version name as its node name and the created date as the value of its jcr:created property.
The versionable state of N is recorded in the frozen node F of V as described in §3.13.9 Versionable State. Under full versioning, F is added as the jcr:frozenNode child node of V.
V is added to the version history of N as the direct successor of the base version of N. Under full versioning:
The jcr:predecessors property of N is copied to the jcr:predecessors property of V.
The jcr:predecessors property of N is set to the empty array.
A reference to V is added to the jcr:successors property of each of the nt:version nodes referred to by the jcr:predecessors property of V.
The base version of N is changed to V. Under full versioning, the jcr:baseVersion property of N is changed to refer to V.
The jcr:isCheckedOut property of N is set to false. This change is a workspace-write and therefore does not require a save.
N is now checked-in.
V is returned.
A version is represented by a Version object.
The name given to a version is automatically generated and must be unique within its version history. How the name is generated is up to the implementation. The name of a version is retrieved with the method
inherited by Version. Under simple versioning this is the only inherited method that is required to function (see §188.8.131.52 Version Extends Node).
returns a timestamp indicating the date and time that the version was created. The precision of the timestamp is implementation-dependent.
returns the VersionHistory that contains this Version.
returns the direct predecessors of this Version. Under simple versioning this set will be at most of size 1. Under full versioning, this set maybe of size greater than 1, indicating a merge within the version graph.
returns the direct predecessor of this Version along the same line of descent returned by VersionHistory.getAllLinearVersions in the current workspace (see §184.108.40.206 Current Session and Workspace), or null if no such direct predecessor exists. Note that under simple versioning the behavior of this method is equivalent to getting the unique direct predecessor (if any) of this version.
returns the direct successors of this Version. Under simple versioning this set will be at most of size 1. Under full versioning, this set maybe of size greater than 1, indicating a branch within the version graph.
returns the direct successor of this Version along the same line of descent returned by VersionHistory.getAllLinearVersions in the current workspace (see §220.127.116.11 Current Session and Workspace), or null if no such direct successor exists. Note that under simple versioning the behavior of this method is equivalent to getting the unique direct successor (if any) of this version.
The frozen node of a version is access with
Under simple versioning without in-content version store the frozen node has no parent and therefore methods that depend on a node being within the workspace tree (Item.getPath(), Item.getParent(), etc.) throw RepositoryException. Under full versioning a frozen node is the child of an nt:version within the in-content version store and so has all the characteristics of a normal node.
The Version interface extends Node. Under simple versioning, however, versions are not represented by nodes in content, consequently the inherited methods, other than Item.getName() (see §18.104.22.168 Version Name), are not required to function. These methods may throw a RepositoryException. Under full versioning the methods of Version inherited from Node function on the actual node in content that backs that version (see §22.214.171.124 nt:version).
When a versionable node is checked in, it and its subgraph become read-only. The effect of read-only status on a node depends on the on-parent-version (OPV) status of each of its child items.
When a node N becomes read-only:
No property of N can be added, removed or have its value changed unless it has an on-parent-version setting of IGNORE.
No child node of N can be added or removed unless it has an on-parent-version setting of IGNORE.
Every existing child node of N becomes read-only unless it has an on-parent-version setting of IGNORE or has an on-parent-version setting of VERSION and is itself versionable.
These restrictions apply to all methods with the exception of VersionManager.restore, VersionManager.restoreByLabel (see §15.7 Restoring a Version), VersionManager.merge (see §15.9 Merge) and Node.update (see §10.8.3 Updating Nodes Across Workspaces). These operations do not respect checked-in status.
Note that remove of a read-only node is possible, as long as its parent is not read-only, since removal is an alteration of the parent node.
A checked-in node is checked-out using
void VersionManager.checkout(String absPath),
where absPath is the absolute path of the node.
The checked-out state indicates to the repository and other clients that the latest version of N is “being worked on” and will typically be checked-in again at some point in the future, thus creating a new version.
On checkout of a node N:
If N is already checked-out, this method has no effect.
If N is not versionable, an UnsupportedRepositoryOperationException is thrown.
The jcr:isCheckedOut property of N is set to true.
N and all nodes and properties in the subgraph of N lose their read-only status.
Under full versioning, the current value of the jcr:baseVersion property of N is copied to the jcr:predecessors property of N.
This method is a workspace-write. There is no need to call save.
Only the actual versionable node has a jcr:isCheckedOut property, however, the checked-in read-only effect extends into the subgraph of the versionable node (see §15.2.2 Read-Only on Check-In). The method
boolean VersionManager.isCheckedOut(String absPath)
returns false if the node at absPath is read-only due to a check-in operation. The method returns false otherwise.
Alternatively, the method
can also be used directly on the node in question.
Version VersionManager.checkpoint(String absPath)
is a shortcut for checkin followed immediately by checkout.
A version label is a JCR name (see §3.2 Names) associated with a version. A version may have zero or more labels. Within a given version history, a particular label may appear a maximum of once. Labels are typically used to add application-level information to a stored version.
Under simple versioning labels are added, accessed and removed only through the version-label-specific API.
Under full versioning version labels are also exposed in content. Each nt:versionHistory node has a subnode called jcr:versionLabels of type nt:versionLabels:
- * (REFERENCE) protected ABORT
Each version label is stored as a REFERENCE property whose name is the label name and whose target is the nt:version node within the nt:versionHistory to which the label applies. Dereferencing a label property is equivalent to calling VersionHistory.getVersionByLabel.
adds the specified label to the version with the specified versionName. The label must be a JCR name in either qualified or expanded form and therefore must conform to the syntax restrictions that apply to such names. In particular a colon (“:”) should not be used unless it is intended as a prefix delimiter in a qualified name (see §3.2.5 Lexical Form of JCR Names).
In a full versioning system, VersionHistory.addVersionLabel adds the appropriate REFERENCE to the nt:versionLabels node. The addition of a label is a workspace-write and therefore does not require a save.
If the specified label is already assigned to a version in this history and moveLabel is true then the label is removed from its current location and added to the version with the specified versionName. If moveLabel is false, then an attempt to add a label that already exists in this version history will throw a LabelExistsVersionException.
boolean VersionHistory.hasVersionLabel(String label)
returns true if any version in the version history has the given label. The method
returns true if the specified version has the specified label.
returns all the version labels on all the versions in the version history. The method
String VersionHistory.getVersionLabels(Version version)
returns all version labels on the specified version.
void VersionHistory.removeVersionLabel(String label)
removes the specified label from this version history.
In a full versioning system, VersionHistory.removeVersionLabel removes the appropriate REFERENCE from the nt:versionLabels. The change is a workspace-write and therefore does not require a save.
In simple versioning, version histories are not searchable from within the JCR API. In order to make version histories searchable under JCR, version storage must be exposed in content. Since simple versioning repositories may expose version storage (it is simply not required), searchable versions are effectively an optional extension of simple versioning (see §3.13.7 Version Storage and §6 Query).
Under full versioning, the exposure of version storage as content in the workspace allows the stored versions and their associated version meta-data to be searched or traversed just like any other part of the workspace.
When an nt:versionHistory or nt:version node is acquired through a query or directly through a getNode, the actual Java type of the returned object must be VersionHistory (in the case nt:versionHistory nodes) or Version (in the case of nt:version nodes). This allows the application to cast the returned object to either Version or VersionHistory and use it in methods that take those types.
Restoring a versionable node to the state recorded in an earlier version can be done with
VersionManager.restore (Version version,
Given a version V and a boolean flag B, and letting N be the versionable node in this workspace of which V is a version and F be the frozen node of V, on restore(V, B), if N has unsaved changes pending, an InvalidItemStateException is thrown, otherwise:
Under simple versioning, if N is checked-in then it is automatically checked-out before the restore is performed.
Under full versioning the restore methods work regardless of whether the node in question is checked-out or checked-in.
Under both simple and full versioning, the changes are made through workspace-write and therefore do not require save.
The primary type, mixin types and identifier of N are set as follows:
The jcr:primaryType property of N (and, semantically, the actual primary node type of N) is set to the value recorded in the jcr:frozenPrimaryType of F.
The jcr:mixinTypes property of N (and, semantically, the actual mixin node types of N) is set to the value(s) recorded in the jcr:frozenMixinTypes of F.
The jcr:uuid property of N (and, semantically, the actual identifier of N) is set to the value recorded in the jcr:frozenUuid of F.
For each property P present on F (other than jcr:frozenPrimaryType, jcr:frozenMixinTypes and jcr:frozenUuid):
If P has an OPV of COPY or VERSION then F/P is copied to N/P, replacing any existing N/P.
F will never have a property with an OPV of IGNORE, INITIALIZE, COMPUTE or ABORT (see §15.2 Check-In: Creating a Version).
For each property P present on N but not on F:
If P has an OPV of COPY, VERSION or ABORT then N/P is removed. Note that while a node with a child item of OPV ABORT cannot be versioned, it is legal for a previously versioned node to have such a child item added to it and then for it to be restored to the state that it had before that item was added, as this step indicates.
If P has an OPV of IGNORE then no change is made to N/P.
If P has an OPV of INITIALIZE then, if N/P has a default value (either defined in the node type of N or implementation-defined) its value is changed to that default value. If N/P has no default value then it is left unchanged.
If P has an OPV of COMPUTE then the value of N/P may be changed according to an implementation-specific mechanism.
An identifier collision occurs when a node exists outside the subgraph rooted at A with the same identifier as a node that would be introduced by the restore operation. The result in such a case is governed by the removeExisting flag. If removeExisting is true, then the incoming node takes precedence, and the existing node (and its subgraph) is removed (if possible; otherwise a RepositoryException is thrown). If removeExisting is false, then an ItemExistsException is thrown and no changes are made.
Each child node C of N where C has an OPV of VERSION and C is mix:versionable, is represented in F not as a copy of N/C but as special node containing a reference to the version history of C. On restore, the following occurs.
If the workspace currently has an already existing node corresponding to C’s version history and the removeExisting flag of the restore is set to true, then that instance of C becomes the child of the restored N.
If the workspace currently has an already existing node corresponding to C’s version history and the removeExisting flag of the restore is set to false then an ItemExistsException is thrown.
If the workspace does not have an instance of C then one is restored from C’s version history:
If the restore was initiated through a restoreByLabel where L is the specified label and there is a version of C with the label L then that version is restored.
If the version history of C does not contain a version with the label L or the restore was initiated by a method call that does not specify a label then the workspace in which the restore is being performed will determine which particular version of C will be restored. This determination depends on the configuration of the workspace and is outside the scope of this specification.
For each child node C present on F:
If C has an OPV of COPY or VERSION:
B is true, then F/C and its subgraph is copied to N/C, replacing any existing N/C and its subgraph and any node in the workspace with the same identifier as C or a node in the subgraph of C is removed.
B is false, then F/C and its subgraph is copied to N/C, replacing any existing N/C and its subgraph unless there exists a node in the workspace with the same identifier as C, or a node in the subgraph of C, in which case an ItemExistsException is thrown , all changes made by the restore are rolled back leaving N unchanged.
Under full versioning each child node C of N where C has an OPV of VERSION and C is versionable, is represented in F not as a copy of N/C but as special node of type nt:versionedChild containing a reference to the version history of C. On restore, N/C in the workspace is replaced by a version of C. The determination of which version of C to use is implementation-dependent (see §15.7.5 Chained Versions on Restore).
In a repository that supports orderable child nodes, the relative ordering of the set of child nodes C that are copied from F is preserved.
F will never have a child node with an OPV of IGNORE, INITIALIZE, COMPUTE or ABORT (see §15.2 Check-In: Creating a Version).
For each child node C present on N but not on F:
If C has an OPV of COPY, VERSION or ABORT then N/C is removed. Note that while a node with a child item of OPV ABORT cannot be versioned, it is legal for a previously versioned node to have such a child item added to it and then for it to be restored to the state that it had before that item was added, as this step indicates.
If C has an OPV of IGNORE then no change is made to N/C.
If C has an OPV of INITIALIZE then N/C is re-initialized as if it were newly created, as defined in its node type.
If C has an OPV of COMPUTE then N/C may be re-initialized according to an implementation-specific mechanism.
Under simple versioning N is automatically checked-in.
Under full versioning the jcr:isCheckedOut property of N is set to false (though the other elements of a check-in are not performed). Additionally, the jcr:baseVersion property of N is set to V. Note that after the next check-out (see §15.3 Check-Out) and subsequent check-in of N the version V will acquire an additional direct successor, forming a branch.
takes the Version object and a target path. This method only works in cases where no node exists at absPath. It is used to restore nodes that have been removed or to introduce new subgraphs into a workspace based on state stored in a version.
takes a version name instead of the actual Version object. The version to be restored is identified by name from within the version history of the node at absPath. This method requires that the node at absPath exist and be a versionable node.
takes a version label instead of a Version object (see §15.2.1 Version Object). The version to be restored is identified by label from within the version history of the node at absPath. This method requires that the node at absPath exist and be a versionable node.
restore(Version versions, boolean removeExisting)
is used to simultaneously restore multiple versions. This may be necessary in cases where sequential restoration is impossible due to a cycle of REFERENCE properties in the nodes to be restored.
In some implementations it may be possible to remove versions from within a version history using VersionHistory.removeVersion. In such cases the version graph must be automatically repaired so that the direct successor of the removed version becomes the direct successor of the direct predecessor of the removed version.
void VersionHistory.removeVersion(String versionName)
removes the named version from this version history and automatically repairs the version graph. If the version to be removed is V, V's direct predecessor set is P and V's direct successor set is S, then the version graph is repaired s follows:
For each member of P, remove the reference to V from its direct successor list and add references to each member of S.
For each member of S, remove the reference to V from its direct predecessor list and add references to each member of P.
This change is a workspace-write; there is no need to call save.
merge(String absPath, String srcWorkspace,
boolean bestEffort, boolean isShallow)
performs the first step in a merge of two corresponding nodes:
The merge method can be called on a versionable or non-versionable node.
Like update, merge does not respect the checked-in status of nodes. A merge may change a node even if it is currently checked-in.
If this node (the one on which merge is called) does not have a corresponding node in the indicated workspace, then the merge method returns quietly and no changes are made.
If isShallow is true and this node, despite having a corresponding node, is nevertheless non-versionable then the merge method also returns quietly and no changes are made.
Otherwise, the following happens:
If isShallow is true then a merge test is performed on this node, call it N. If isShallow is false then a merge test is performed recursively on each versionable node, N within the subgraph rooted at this node.
The merge test is performed by comparing N with its corresponding node in srcWorkspace, call it N'.
The merge test is done by comparing the base version of N (call it V) and the base version of N' (call it V').
For any versionable node N there are three possible outcomes of the merge test: update, leave or failed.
If N does not have a corresponding node then the merge result for N is leave.
If N is currently checked-in then:
If V' is an eventual successor of V, then the merge result for N is update.
If V' is an eventual predecessor of V or if V and V' are identical (i.e., are actually the same version), then the merge result for N is leave.
If V is neither an eventual successor of, eventual predecessor of, nor identical with V', then the merge result for N is failed. This is the case where N and N' represent divergent branches of the version graph.
If N is currently checked-out then:
If V' is an eventual predecessor of V or if V and V' are identical (i.e., are actually the same version), then the merge result for N is leave.
If any other relationship holds between V and V', then the merge result for N is fail.
If bestEffort is false then the first time a merge result of fail occurs, the entire merge operation on this subgraph is aborted, no changes are made to the subgraph and a MergeException is thrown. If no merge result of fail occurs then:
Each versionable node N with result update is updated to reflect the state of N'. The state of a node in this context refers to its set of properties and child node links.
Each versionable node N with result leave is left unchanged, unless N is the child of a node with status update and N does not have a corresponding node in srcWorkspace, in which case it is removed.
If bestEffort is true then:
Each versionable node N with result update is updated to reflect the state of N'. The state of a node in this context refers to its set of properties and child node links.
Each versionable node N with result leave is left unchanged, unless N is the child of a node with status update and N does not have a corresponding node in srcWorkspace. I such a case, N is removed.
Each versionable node N with result failed is left unchanged except that the identifier of V' (which is, in some sense, the “offending” version; the one that caused the merge to fail on that N) is added to the multi-value REFERENCE property jcr:mergeFailed of N. If the identifier of V' is already in jcr:mergeFailed, it is not added again. The jcr:mergeFailed property never contains repeated references to the same version. If the jcr:mergeFailed property does not yet exist then it is created. If present, the jcr:mergeFailed property will always contain at least one value. If not present on a node, this indicates that no merge failure has occurred on that node. Note that the presence of this property on a node will in any case prevent it from being checked-in because the OnParentVersion setting of jcr:mergeFailed is ABORT.
This property can later be used by the application to find those nodes in the subgraph that have failed to merge and thus require special attention (see §15.9.2 Merging Branches). This property is multi-valued so that a record of successive failed merges can be kept.
In either case, (regardless of whether bestEffort is true or false) for each non-versionable node (including both referenceable and non-referenceable), if the merge result of its nearest versionable ancestor is update, or if it has no versionable ancestor, then it is updated to reflect the state of its corresponding node. Otherwise, it is left unchanged. The definition of corresponding node in this context is the same as usual: the match is done by identifier.
Note that a deep merge performed on a subgraph with no versionable nodes at all (or indeed in a repository that does not support versioning in the first place) will be equivalent to an update.
The merge method returns a NodeIterator over all versionable nodes in the subgraph that received a merge result of fail.
Note that if bestEffort is false, then merge will either return an empty iterator (since no merge failure occurred) or throw a MergeException (on the first merge failure that was encountered).
If bestEffort is true, then the iterator will contain all nodes that received a fail during the course of this merge operation.
All changes made by merge are workspace-write, and therefore this method does not require a save.
The above declarative description can also be expressed in pseudo-code as follows:
be the workspace against which the merge
let bestEffort be the flag passed to merge.
let isShallow be the flag passed to merge.
let failedset be a set of identifiers, initially empty.
let startnode be the node on which merge was called.
return the nodes with the identifiers in failedset.
let n' be the corresponding node of n in ws'.
if no such n' doleave(n).
else if n is not versionable doupdate(n, n').
else if n' is not versionable doleave(n).
let v be base version of n.
let v' be base version of n'.
if v' is an eventual successor of v and
n is not checked-in doupdate(n, n').
else if v is equal to or an eventual predecessor of v' doleave(n).
else dofail(n, v').
if bestEffort = false throw MergeException.
else add identifier of v' (if not already present) to the
jcr:mergeFailed property of n,
add identifier of n to failedset,
if isShallow = false
for each versionable child node c of n domerge(c).
if isShallow = false
for each child node c of n domerge(c).
replace set of properties of n with those of n'.
let S be the set of child nodes of n.
let S' be the set of child nodes of n'.
judging by the name of the child node:
let C be the set of nodes in S and in S'
let D be the set of nodes in S but not in S'.
let D' be the set of nodes in S' but not in S.
remove from n all child nodes in D.
for each child node of n' in D' copy it (and its subgraph) to n
as a new child node (if an incoming node has the same
identifier as a node already existing in this workspace,
the already existing node is removed).
for each child node m of n in C domerge(m).
When a merge test on a node N fails, this indicates that the two base versions V and V' are on separate branches of the version graph. Consequently, determining the result of the merge is not simply a matter of determining which version is the eventual successor of the other in terms of version history. Instead, the subgraph of N' must be merged into the subgraph of N according to some domain specific criteria which must be performed at the application level, for example, through a merge tool provided to the user.
The jcr:mergeFailed property is used to tag nodes that fail the merge test so that an application can find them and deal appropriately with them. The jcr:mergeFailed property is multi-valued so that information about merge failures is not lost if more than one successive merge is attempted before being dealt with by the application.
After the subgraph of N' is merged into N, the application must also merge the two branches of the version graph. This is done by calling N.doneMerge(V') where V' is retrieved by following the reference stored in the jcr:mergeFailed property of N. This has the effect of moving the reference-to-V' from the jcr:mergeFailed property of N to its jcr:predecessors property.
If, on the other hand, the application chooses not to join the two branches, then cancelMerge(V') is performed. This has the effect of removing the reference to V' from the jcr:mergeFailed property of N without adding it to jcr:predecessors.
Once the last reference in jcr:mergeFailed has been either moved to jcr:predecessors (with doneMerge) or just removed from jcr:mergeFailed (with cancelMerge) the jcr:mergeFailed property is automatically removed, thus enabling this node to be checked-in, creating a new version (note that before the jcr:mergeFailed is removed, its OnParentVersion setting of ABORT prevents check-in). This new version will have a direct predecessor connection to each version for which doneMerge was called, thus joining those branches of the version graph.
All changes made by doneMerge and cancelMerge are workspace-write and therefore do not require save.
In repositories that support activities (see §15.12 Activities) merging an activity into another workspace is done with the method
(see §15.12.7 Merging an Activity into Another Workspace).
Serialization of version information can be done in the same way as normal serialization by serializing the subgraph below /jcr:system/jcr:versionStorage. The special status of these nodes with respect to versioning is transparent to the serialization mechanism.
The serialized content of the source version storage can be imported as “normal” content on the target repository, but it will not actually be interpreted and integrated into the repository as version storage data unless it is integrated into or used to replace the target repository's own version storage.
Methods for doing this kind of “behind the scenes” alteration to an existing version storage (whether based on the serialized version storage of another repository, or otherwise) are beyond the scope of this specification.
In a repository that supports both versioning and transactions, all versioning operations must be fully transactional, meaning that they can be bracketed within a transaction and rolled-back just like any other set of operations.
Activities provide a way of grouping together a set of logically related changes performed in a workspace and then later merging this set of changes into another workspace.
Before starting to make a particular set of changes, the user sets the current activity. Each subsequent checkout made within the scope of that activity will associate that activity with that checked-out versionable, and will create a version that is tagged with the specified activity when that versionable is subsequently checked-in.
Abstractly, therefore, an activity is a set of changes that produce new versions. However, if that set includes changes that produce more than one version within a particular version history, then those versions must all be on the same line of descent, that is, there must be a non-branching sequence of direct successor relationships beginning at the root version of the version history that reaches every version in the set. This ensures that there is always at most one “latest” version that contains all changes in a given version history for a given activity.
Support for activities is an optional addition to the full versioning feature. An implementation that supports versioning may support activities.
Whether a particular implementation supports activities can be determined by querying the repository descriptor table with
A return value of true indicates support for activities (see §24.2 Repository Descriptors).
Activities are represented by nodes of node type nt:activity:
[nt:activity] > mix:referenceable
- jcr:activityTitle (STRING) mandatory autocreated protected
The relationship between version and activity is modeled by the property jcr:activity, in the mix:versionable and nt:version node types:
- jcr:versionHistory (REFERENCE) mandatory protected IGNORE
- jcr:baseVersion (REFERENCE) mandatory protected IGNORE
- jcr:predecessors (REFERENCE) mandatory protected multiple
IGNORE < 'nt:version'
- jcr:mergeFailed (REFERENCE) protected multiple ABORT
- jcr:activity (REFERENCE) protected IGNORE < 'nt:activity'
jcr:configuration (REFERENCE) protected IGNORE
[nt:version] > mix:referenceable
jcr:created (DATE) mandatory autocreated protected
- jcr:predecessors (REFERENCE) protected multiple ABORT
- jcr:successors (REFERENCE) protected multiple ABORT
- jcr:activity (REFERENCE) protected ABORT < 'nt:activity'
+ jcr:frozenNode (nt:frozenNode) protected ABORT
Activities are persisted as nodes of type nt:activity under system-generated node names in activity storage below /jcr:system/jcr:activities.
The organization of this subgraph is left up to the implementation (for example, there may be intervening nodes structuring the activity storage).
Similar to the /jcr:system/jcr:versionStorage subgraph, the activity storage is a single repository wide store, but is reflected into each workspace. However access control may be employed so that different sessions see different parts of the tree.
The activity storage subgraph is not writable through the core write methods (see §10.2 Core Write Methods). It can only be altered through the activity-specific write methods described in this section.
Activities are created using:
Node VersionManager.createActivity(String title)
creates a new nt:activity node at an implementation-determined location in the /jcr:system/jcr:activities subgraph and returns it.
The name of the nt:activity node is automatically generated by the repository. The repository may use the title parameter as a hint to give a value to the jcr:activityTitle property of the new node. The new node addition is dispatched immediately and therefore does not require a save.
Node VersionManager.setActivity(Node activity)
is called by the user to set the current activity on the session by specifying a previously created nt:activity node. Changing the current activity is done by calling setActivity again. Cancelling the current activity is done by calling setActivity(null) and results in the session having no current activity. The method returns the previously set nt:activity node or null if no such node exists.
the current activity of session S is represented by node A and
node N is a versionable node with version history H,
then each checkout of node N made through S while A is in effect causes the following:
If there exists another workspace with node N' where N' also has version history H, N' is checked out and the jcr:activity property of N' references A, then the check-out fails with an ActivityViolationException indicating which workspace currently has the check-out.
If there is a version in H that is not an eventual predecessor of N but whose jcr:activity references A, then the check-out fails with an ActivityViolationException.
Otherwise, the jcr:activity property of N is set to reference A and when N is subsequently checked in, the jcr:activity property of the new version is set to reference A, and the jcr:activity property of N is removed.
returns the node representing the current activity or null if there is no current activity.
Once an activity has been completed, the changes that it records can be imported into another workspace. This is done with a variant of the merge method:
NodeIterator VersionManager.merge(Node activityNode)
This method merges the changes that were made under the specified activity into this workspace.
An activity A will be associated with a set of versions through the jcr:activity reference of each version node in the set. We call each such associated version a member of A.
For each version history H that contains one or more members of A, one such member will be the latest member of A in H. The latest member of A in H is the version in H that is a member of A and that has no eventual successor versions that are also members of A.
The set of versions that are the latest members of A in their respective version histories is called the change set of A. It fully describes the changes made under the activity A.
This method performs a shallow merge, with bestEffort equal to true, into this workspace (see §15.9 Merge) of each version in the change set of the activity specified by activityNode. If there is no corresponding node in this workspace for a given member of the change set, that member is ignored.
This method returns a NodeIterator over all versionable nodes in the subgraph that received a merge result of fail (see §15.9.1 Merge Algorithm).
All changes made through this method are workspace-write and therefore do not require save.
Some repositories may support
void VersionManager.removeActivity(Node activityNode)
which removes the specified activity node from the activity storage and automatically removes all REFERENCE properties referring to that node in all workspaces, with the exception of REFERENCE properties in version storage. The existence of a REFERENCE to the activity node from within version storage will cause an exception to be thrown. Changes made through this method are workspace-write and therefore do not require save.
A configuration is the subgraph of a specifically designated versionable node (called the configuration root node) in a workspace, minus any parts of that subgraph that are themselves designated as configurations. A baseline is the state of a configuration at some point in time, recorded in version storage as a version object.
Support for configurations and baselines is an optional addition to the full versioning feature. An implementation that supports full versioning may support configurations and baselines. Whether a particular implementation supports configurations and baselines can be determined by querying the repository descriptor table with
A return value of true indicates support for configurations and baselines (see §24.2 Repository Descriptors).
Each configuration in a given workspace is represented by a distinct proxy node of type nt:configuration located in configuration storage within the same workspace under /jcr:system/jcr:configurations/. The configuration storage in a particular workspace is specific to that workspace. It is not a common repository-wide store mirrored into each workspace, as is the case with version storage.
The proxy node of a configuration is used to perform certain operations on that configuration. In particular, version operations performed on the proxy node act not only on that node itself but also on the configuration it represents, as a whole. Creating a baseline, for example, is done by performing a checkin on a configuration’s proxy node.
Every configuration proxy node is of type nt:configuration:
[nt:configuration] > mix:versionable
- jcr:root (REFERENCE) mandatory autocreated protected
This node type is a subtype of mix:versionable and adds a single property, the REFERENCE property jcr:root, which points to the root node of the configuration that this proxy represents.
Since every configuration proxy node is versionable, each has a version history. The versions within this history store state information about configuration represented by the proxy node, in addition to information about the proxy node itself.
The organization of configuration storage is left up to the implementation (for example, there may be intervening nodes structuring the storage). It is expected that access control will also be employed to ensure that only sessions with appropriate authorization may create or have access to particular configurations.
A configuration is created by designating a mix:versionable node N in the workspace as a configuration root node. This is done by calling
where absPath is the path of N.
On creation of a new configuration with root N, a new proxy node C, of type nt:configuration, is created under /jcr:system/jcr:configurations/ and a new version history HC is created for C with a root version B0. Note that HC is also called a baseline history and its contained versions, including B0, are called baselines. The baselines within HC store not only the state of C but also the state of the configuration represented by C (see 126.96.36.199 Creating a Baseline).
The properties of C and N are initialized as follows:
N/jcr:configuration points to C.
C/jcr:root points to N.
C/jcr:versionHistory points to HC.
C/jcr:baseVersion points to B0.
The createConfiguration call will fail if
the node at absPath is not mix:versionable.
the node at absPath is already a configuration root (i.e., if it already has a jcr:configuration property).
There exists in the subgraph at N a versionable node that has never been checked-in (i.e., one whose base version is still its root version).
The createConfiguration method is workspace-write. Therefore the changes it makes are dispatched immediately and a save is not required.
A baseline records the state of a configuration at some particular time and is represented by a version (i.e., an nt:version node) of the nt:configuration node in question.
A baseline is created by performing a checkin on a configuration proxy node (i.e., a node of type nt:configuration found in configuration storage). Note that since nt:configuration is subtype of mix:versionable, a configuration node will have its own version history, distinct from the version history of its configuration root node.
On checkin of the configuration proxy node C:
The state of the C is recorded in a new baseline B just as it would be in a normal version.
In addition, the current base version of every versionable node in the configuration is also recorded.
How the configuration state information is stored is up to the repository. It need not be stored as content in the substructure of the nt:version node. For example, some repositories are likely to have some efficient internal mechanisms involving lists of identifiers, possibly stated as a delta against the direct predecessor baseline. The only requirement is that baselines be “restoreable”.
Using the method
VersionManager.restore(Version version, boolean removeExisting)
where version is a baseline Version object, C is the nt:configuration node whose version history contains version and N is the configuration root node pointed to by C/jcr:root:
The state of C is restored to the state recorded in version and C/jcr:baseVersion is set to point to version (as in the restore of any normal version).
Each versionable node M in the subgraph below and including N is restored to the state recorded in V where V is the version of M in M’s version history that was recorded in B (i.e., the base version of M at the time B was created).
The removeExisting parameter behaves just as in a normal restore expect that that it applies to all nodes restored below N. The same behavior applies for the multi-version signature of restore,
except that multiple baselines may be restored simultaneously.
where version is a baseline Version object and absPath is a path to a location where no node exists but which has a suitable parent node, creates a new configuration at absPath by restoring the baseline version. A configuration proxy node C with C/jcr:root pointing to the root node of the new configuration at absPath is automatically created in configuration storage. If a node already exists at absPath, the method fails. The variant signatures
work identically except that the baseline to be restored is identified either by name or by label instead of being passed in as a Version object.