摘要:
Techniques are provided for facilitating uniform access control to data managed by a database server that can emulate hierarchically organized systems, whether the data is accessed through hierarchical or relational access mechanisms. A database server that can emulate hierarchically organized systems uses separate relational or object-relational database tables to store the content of the resources that belong to a hierarchy (the “content structures”) and information that captures the hierarchy (the “hierarchy structures”). Both types of structures contain access control data that define consistent user access privileges. To determine access privileges for a user requesting access to data in the database, access control information is accessed in the hierarchy structures when the request is made through the hierarchical access mechanism, or accessed in the content structures when the request is made through a relational access mechanism. Access control is consistent between the hierarchical or relational access mechanisms because access through either is governed by user access data that reflects the same privileges.
摘要:
In a multi-tier data server system, data from the first tier is cached in a mid-tier cache of the middle tier. Access control information from the first tier for the data is also cached within the mid-tier cache. Caching the security information in the middle tier allows the middle tier to make access control decisions regarding requests for data made by clients in the outer tier.
摘要:
A method and apparatus for performing an action in response to a file system event is provided. According to one aspect, sets of “event listeners” are associated with a file hierarchy and/or the nodes thereof. Each event listener contains a set of “event handlers.” Each event handler corresponds to a separate type of event that may occur relative to the file hierarchy's nodes. When an event is going to occur relative to the hierarchy or a node thereof, all event listeners that are associated with that hierarchy/node are inspected to determine whether those event listeners contain any event handlers that correspond to the event's type. Those event handlers that correspond to the event's type are placed in an ordered list of event handlers to be invoked. As the event handlers in the list are invoked, programmatic mechanisms that correspond to those event handlers are executed to perform customized user-specified actions.
摘要:
A method and apparatus for performing an action in response to a file system event is provided. According to one aspect, sets of “event listeners” are associated with a file hierarchy and/or the nodes thereof. Each event listener contains a set of “event handlers.” Each event handler corresponds to a separate type of event that may occur relative to the file hierarchy's nodes. When an event is going to occur relative to the hierarchy or a node thereof, all event listeners that are associated with that hierarchy/node are inspected to determine whether those event listeners contain any event handlers that correspond to the event's type. Those event handlers that correspond to the event's type are placed in an ordered list of event handlers to be invoked. As the event handlers in the list are invoked, programmatic mechanisms that correspond to those event handlers are executed to perform customized user-specified actions.
摘要:
In-place XML schema evolution occurs by evaluating an existing XML schema in a database system to see if it is compatible with a new XML schema. To determine if the old schema is compatible with the new schema, a lock-step traversal is performed on the two schemas. Each instruction in the old schema is compared to instructions in the new schema. Detected differences between the two schemas are evaluated to determine if existing XML documents are still compatible with the new schema. If they are, then an in-place schema evolution operation can take place. The in-place schema operation basically, involves appending the updated object information to the underlying object type and preserving the order of elements in a document by storing element mapping information on disk.
摘要:
In a multi-tier data server system, data from the first tier is cached in a mid-tier cache of the middle tier. Access control information from the first tier for the data is also cached within the mid-tier cache. Caching the security information in the middle tier allows the middle tier to make access control decisions regarding requests for data made by clients in the outer tier.
摘要:
In-place XML schema evolution occurs by evaluating an existing XML schema in a database system to see if it is compatible with a new XML schema. To determine if the old schema is compatible with the new schema, a lock-step traversal is performed on the two schemas. Each instruction in the old schema is compared to instructions in the new schema. Detected differences between the two schemas are evaluated to determine if existing XML documents are still compatible with the new schema. If they are, then an in-place schema evolution operation can take place. The in-place schema operation basically, involves appending the updated object information to the underlying object type and preserving the order of elements in a document by storing element mapping information on disk.
摘要:
A method and apparatus for providing file system operation locks at a database server is provided. A database server may employ database locks and file system operation locks in servicing requests from consistent requestors and inconsistent requesters. A database lock is a lock that is obtained in response to performing a database operation, and the database lock is released when the database operation has successfully completed. A file system operation lock is a lock that is obtained in response to performing an OPEN file system operation, and the file system operation lock is released when a CLOSE file system operation is performed. The database server may use a temporary copy of the resource, which reflects all the current changes that have been made to the resource by database operations, in servicing consistent requestors, and may use the original version of the resource in servicing inconsistent requesters.
摘要:
A method and apparatus for performing file system operation locks at a database server is provided. A request to perform a file operation on a portion of a file managed by a database server is received at the database server. In response to receiving the request, the database server grants a lock that covers only a portion of the file that is involved in the file operation. For example, the database server may grant a lock that covers a range of bytes on the file, where the range of bytes is less than the entire file. Thereafter, the database server performs the file operation on the file. The file operation may be a NFS operation.
摘要:
A method and system for evolving XML-schema-based data to conform to an evolved XML schema is disclosed. Based on an existing XML schema and an instance document that is based on the existing XML schema, an XML-schema-independent form of the instance document is generated. Based on a set of specified transformations and the XML-schema-independent form of the instance document, an evolved instance document is generated. The evolved instance document conforms to an evolved XML schema that incorporates changes to the existing XML schema. Techniques described herein are flexible enough to accommodate a wide variety of evolutions to XML schemas.