JCR Browser

The JCR browser is a tool for exploring the Java Content Repository (JCR) used by XperienCentral to store website data. It allows you to browse through the repository by expanding/collapsing sub trees in the same way as with File Explorer in Microsoft Windows. You can perform the following operations on JCR tree items:

• Nodes - you can create, move and delete.
• Properties - you can create, edit and delete.

Due to node type definitions, the JCR browser cannot perform all operations on every node. If you try to create an improper child node or property, the JCR browser will return an error. Additonally, you can perform queries on the JCR tree. With queries you can search for specific content. The JCR browser supports the XPath and SQL syntaxes.

In This Topic

Introduction to JCR

 Click here for an introduction to the Content Repository API for Java (JCR)

A Java Content Repository (JCR) is a database with a standardized Java Application Programming Interface (API). A JCR allows different applications to access one centralized database. Other technologies that are comparable to JCR are JDBC, Hibernate and WebDAV. Unlike relational databases, a JCR has a hierarchical tree structure. The tree consists of nodes and properties. The properties are the leaves of the tree and represent the actual pieces of database content. A property is of one of the following types: string, binary, date, a number type, boolean, name, path or reference.

In addition, a node contains attributes that are related to the node itself, for example the name of the node, its path in the tree, its depth in the tree and its type. Therefore, a node has attributes and it contains properties. The organization of the repository into a tree structure is done by the JCR Browser: Internally the content may be stored in a relational database.

Node Types

Every node has one primary node type. The primary node type defines the properties and child nodes that it is allowed or required to have. Every node has a special property called jcr:primaryType that records the name of its primary node type. In addition to its primary node type, a node may also have one or more mixin types. A mixin node type can mandate more child nodes and properties in addition to those enforced by its primary node type.

Multi-value Properties

In some cases, a property may have more than one value. A property that may have more than one value is referred to as a multi-value property. The property definition determines whether a particular property is a multi-value property.

Standardized by JCP

JCR has been standardized by the Java Community Process (JCP) in JSR 170 (API version 1.0) and JSR 283 (API version 2.0). Depending on the API version and compliance level, a JCR may support the following:

• Read-only or read/write access
• Different types of nodes and properties
• Simple or full versioning and multiple languages
• Query languages like XPath, SQL, SQL2, AQM, JQOM
• Locking
• Observation of content changes
• Export and import of content via XML files
• JTA (XA transactions)

See also: http://jcp.org

Using the XperienCentral JCR Browser

To start and use the JCR Browser, follow these steps:

1. Navigate to Configuration > JCR Browser.
2. Select the [JCR Browser] tab.
3. Browse through the tree by expanding or collapsing node sub trees in the "JCR Repository" section.. To expand a node, click + (plus) and to collapse it click – (minus).
4. To select a node, click its icon or name. The attributes of the selected node and the properties it contains, are shown at the right.

Display Tree Property

In the tree view, the name of each node is shown. However, in certain cases the actual node name is different from what is shown in the tree view. In these cases, you need to look at the attributes to see the actual name of the node. The name is shown in the "Display tree property" field. By default it is set to wm:name. This means that for each node the tree viewer tries to find a wm:name property. If a property is present, the value of this property will be shown. If not, the actual node name will be shown.

For example: when you execute the XPath query //element(*, wo:global), the result may be a node that is labeled as follows:

• If the "Display tree property" field is empty, you may see something similar to 751b14124e9caf40ed6c7822d6de. If you expand the tree, you may see something like wo:edit for the child node.
• If the "Display tree property" field is set to wm:name, you may see something like global. If you expand the tree, you may see something like edit for the child node.

Sort by Name

Select "Sort by name" to view the nodes in the tree in alphabetical order.

Node Attributes

When you select a node, the following attributes are shown in the "Node Attributes" section:

Node Properties

When you select a node, the following attributes are shown in the "Node Properties" section:

Following a Tree Reference

If a property is a reference in the JCR tree, its value is shown as a link. Click on the link to navigate to the referenced node in the JCR tree. For example:

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Operations with Nodes

Creating a Node

To create a new node, follow these steps:

1. Select the node for which the new (sub) node will be created.
2. Press the [Add node] button. The "Create node" section appears:
   
   
   
   
3. Select the node type to create from the "Node type" drop-down list.
4. Enter the node name.
5. Click [Create node]. The node is added as a child to the currently selected node in the JCR tree.

Moving a Node

To move a node, follow these steps:

1. Select the node to be moved.
2. Click [Cut] in the "Actions" section.
3. Select the destination node.
4. Click [Paste] in the "Actions" section. The node, including its properties and subtrees, are moved to the destination.

Deleting a Node

To delete a node, follow these steps:

1. Select the node to be deleted.
2. Click [Delete] in the "Actions" section. You are prompted to confirm the action.
3. Click [OK]. The node, including its properties and subtrees, are deleted.

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Operations with Node Properties

Creating a Property

To create a new property for a node, follow these steps:

1. Select the node for which the property is to be created.
2. Press the [Add property] button. The "Add property" section appears.
3. From the pull-down menu, select the definition of the property to be created.
4. Enter the name of the property.
5. From the pull-down menu, select the type of the property to be created.
6. To define a multi-value property, select "Multiple". The [Add value] button appears.
7. Enter the (first) value of the property.
8. Press the [Add] button. The property is added.
9. For multi-value properties, enter the next value and then click [Add value].

Editing a Property

To edit a node property, follow these steps:

1. Click [Edit] next to the property you want to edit. The "Edit property" section appears.
2. Make the desired changes.
3. Press [Set]. The property is changed.

By clicking [Add value] instead of [Set] you create a new instance of the property.

Deleting a Property

To delete a node property, follow these steps:

1. Select the "Delete" checkbox next to the property to be deleted.
2. Click [Delete]. You are prompted to confirm.
3. Click [OK]. The property is deleted.

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Executing JCR Queries

By way of example, the JCR browser is provided with a list of pre-programmed XPath and SQL queries. To this list, you can add your own queries. Your queries are saved and you can edit them at a later time. To execute a query, you just select one from the list, modify it and then execute it.

Creating or Editing a Query

1. Select the JCR Queries tab.
2. From the Queries pull-down menu, select ‘New query’, or an existing query. Notice that you cannot edit preprogrammed queries.
3. Enter or change the name of the query.
4. Select the query syntax type "Xpath" or "SQL".
5. Enter or change the actual query.
6. Click [Apply] to save the query on the list.

Query Examples: SQL Versus XPath

Deleting a Query from the List

1. Select the JCR Queries tab.
2. From the Queries pull-down menu, select the query you want to delete. Notice that you cannot delete pre-programmed queries.
3. Click [Delete query]. The query is removed from the list.

Executing a Query

1. Select the JCR Browser tab.
2. Click [More]. The "Query execution" section appears.
3. Select the query, for instance "MyNodeTypes XPath", from the drop-down list.
4. Modify the query to your needs.
5. Click [Execute query]. The results appear on the Query results tab.

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