Oracle XML DB solves this by providing for name-level locking rather than folder-level locking. In this situation, a conventional locking strategy that takes an exclusive lock on each updated folder or directory tree would quickly result in significant concurrency problems. Once the operation has completed the change is immediately available to all other users of the file system. Each operation (add a file, create a subfolder, rename a file, delete a file, and so on) is treated as an atomic transaction. In conventional file systems there is no concept of a transaction. When using a relational database to maintain hierarchical folder structures, ensuring a high degree of concurrency when adding and removing items in a folder is a challenge. To provide high levels of concurrency, the repository uses name-level locking rather than folder-level locking Applications can create long-running transactions that include updates to multiple folders. One key advantage of Oracle XML DB Repository is the ability to use SQL for repository operations in the context of a logical transaction. They discuss APIs that you can use to access the repository object hierarchy using Java, SQL, and PL/SQL.
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The following topics cover how to access data in Oracle XML DB Repository folders using the standard protocols. A resource has not only content but also associated metadata. Each resource managed by a WebDAV server is identified by a URL. The WebDAV standard uses the term resource to describe a file or a folder. For example, a WebDAV-enabled editor can interact with an HTTP/WebDAV server as if it were a file system. WebDAV lets an HTTP server act as a file server for a DAV-enabled client. These features are available because the repository is modeled on WebDAV, an IETF standard that defines a set of extensions to the HTTP protocol. You can set access control privileges on repository files and folders. The repository gives you direct access to XML content stored in Oracle Database, as if it were stored in a file system.
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By providing support for these protocols, Oracle XML DB lets Microsoft Windows Explorer, Microsoft Office, and products from vendors such as Altova and Adobe work directly with XML content stored in the repository. Oracle XML DB adds native support to Oracle Database for these protocols, which were designed for document-centric operations. Your applications can access content in Oracle XML DB Repository using standard connect-access protocols such as FTP, HTTP(S), and WebDAV, in addition to languages SQL, PL/SQL, Java, and C. Do not add or modify any data in folder /sys. The top of the tree shows /, the root folder.įolder /sys is used by Oracle XML DB to maintain system-defined XML schemas, access control lists (ACLs), and so on. The hierarchical repository index is transparent to end users, and lets Oracle XML DB perform folder and path traversals at speeds comparable to or faster than conventional file systems.įigure 21-1 is an example of a hierarchical structure that shows a typical tree of folders and files in Oracle XML DB Repository. Oracle XML DB includes a patented hierarchical index that speeds up folder and path traversals in Oracle XML DB Repository. It might be more natural to represent a book as a hierarchy, book - chapter - section - paragraph, and to represent the hierarchy as a set of folders and subfolders.Ī hierarchical repository index speeds up folder and path traversals. It can be less effective for managing semi-structured and unstructured data, such as document-oriented XML data.įor example, a book is not easily represented as a set of rows in a table. The relational table-row-column metaphor is an effective model for managing highly structured data. You can query and manage it as if it were organized using files and folders. Oracle XML DB Repository provides you with a hierarchical organization of XML content in the database. Relational databases are traditionally poor at managing hierarchical structures and traversing a path or a URL. Although the repository can manage any kind of content, it provides specialized capabilities and optimizations related to managing resources with XML content. Using Oracle XML DB Repository you can store content in the database in hierarchical structures, as opposed to traditional relational database structures.
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