37 DBMS_EPG

Using DBMS_EPG

• Overview

• Security Model

• Exceptions

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Overview

The DBMS_EPG package is a platform on which PL/SQL users develop and deploy PL/SQL web applications. The embedded PL/SQL gateway is an embedded version of the gateway that runs in the XML database HTTP server in the Oracle database. It provides the core features of mod_plsql in the database but does not require the Oracle HTTP server powered by Apache.

In order to make a PL/SQL application accessible from a browser via HTTP, a Database Access Descriptor (DAD) must be created and mapped to a virtual path. A DAD is a set of configuration values used for database access and the virtual path mapping makes the application accessible under a virtual path of the XML DB HTTP Server. A DAD is represented as a servlet in XML DB HTTP Server.

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Security Model

The XDBADMIN role is required to invoke the configuration interface. It may invoked by the database user "XDB".

The authorization interface can be invoked by any user.

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Exceptions

The following table lists the exceptions raised by the DBMS_EPG package.

Data Structures

The DBMS_EPG package defines a TABLE type.

VARCHAR2_TABLE Table Type

This type is used by the procedures GET_ALL_GLOBAL_ATTRIBUTES, GET_ALL_DAD_ATTRIBUTES, GET_ALL_DAD_MAPPINGS, and GET_DAD_LIST to return lists of attribute names, attribute values, virtual paths, and database access descriptors (DAD).

TYPE VARCHAR2_TABLE IS TABLE OF VARCHAR2(4000) INDEX BY BINARY_INTEGER;

Subprogram Groups

The DBMS_EPG consists of two interfaces:

• Configuration Subprograms

• Authorization Subprograms

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Configuration Subprograms

The Configuration subprogram group contain the subprogram interfaces to examine and modify the global and database access descriptor (DAD) specific settings of the embedded PL/SQL gateway.

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Authorization Subprograms

The Authorization subprogram group contains the subprogram interfaces to authorize and deauthorize the use of a database user's privileges by the embedded PL/SQL gateway through a specific database access descriptor (DAD)

Summary of DBMS_EPG Subprograms

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AUTHORIZE_DAD Procedure

This procedure authorizes a DAD to invoke procedures and access document tables with a database user's privileges. The invoker can always authorize the use of her/his own privileges.

Syntax

DBMS_EPG.AUTHORIZE_DAD (
   dad_name  IN  VARCHAR2,
   path     IN  VARCHAR2 DEFAULT NULL);

Parameters

Usage Notes

• To authorize the use of another user's privileges, the invoker must have the ALTER USER system privilege.

• The DAD must exist but its "database-username" DAD attribute does not have to be set to user to authorize.

• Multiple users can authorize the same DAD and it is up to the DAD's "database-username" setting to decide which user's privileges to use.

Exceptions

Raises an error if the DAD or user does not exist, or the invoker does not have the needed system privilege.

Examples

DBMS_EPG.AUTHORIZE_DAD('HR');

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CREATE_DAD Procedure

This procedure creates a new DAD.

Syntax

DBMS_EPG.CREATE_DAD (
   dad_name  IN  VARCHAR2,
   path      IN  VARCHAR2 DEFAULT NULL);

Parameters

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DEAUTHORIZE_DAD Procedure

This procedure deauthorizes a DAD with regard to invoking procedures and accessing document tables with a database user's privileges. The invoker can always deauthorize the use of his own privileges.

Syntax

DBMS_EPG.DEAUTHORIZE_DAD (
   dad_name  IN  VARCHAR2,
   path      IN  VARCHAR2 DEFAULT NULL);

Parameters

Usage Notes

To deauthorize the use of another user's privileges, the invoker must have the ALTER USER system privilege.

Exceptions

Raises an error if the DAD or user does not exist, or the invoker does not have the needed system privilege.

Examples

DBMS_EPG.DEAUTHORIZE_DAD('HR');

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DELETE_DAD_ATTRIBUTE Procedure

This procedure deletes a DAD attribute.

Syntax

DBMS_EPG.DELETE_DAD_ATTRIBUTE (
   dad_name      IN  VARCHAR2,
   attr_name     IN  VARCHAR2);

Parameters

Exceptions

Raises an error if DAD does not exist

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DELETE_GLOBAL_ATTRIBUTE Procedure

This procedure deletes a global attribute.

Syntax

DBMS_EPG.DELETE_GLOBAL_ATTRIBUTE (
   attr_name     IN  VARCHAR2);

Parameters

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DROP_DAD Procedure

This procedure drops a DAD. All the virtual-path mappings of the DAD will be dropped also

Syntax

DBMS_EPG.DROP_DAD (
   dadname  IN  VARCHAR2);

Parameters

Exceptions

Raises an error if the DAD does not exist.

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GET_ALL_DAD_ATTRIBUTES Procedure

This procedure retrieves all the attributes of a DAD. The outputs are 2 correlated index-by tables of the name/value pairs.

Syntax

DBMS_EPG.GET_ALL_DAD_ATTRIBUTES (
   dad_name      IN          VARCHAR2,
   attr_names    OUT NOCOPY  VARCHAR2_TABLE,                       
   attr_values   OUT NOCOPY  VARCHAR2_TABLE);

Parameters

Exceptions

Raises an error if DAD does not exist.

Usage Notes

If the DAD has no attributes set, then attr_names and attr_values will be set to empty arrays.

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GET_ALL_DAD_MAPPINGS Procedure

This procedure retrieves all virtual paths to which the specified DAD is mapped.

Syntax

DBMS_EPG.GET_ALL_DAD_MAPPINGS (
   dad_name      IN          VARCHAR2,
   paths         OUT NOCOPY  VARCHAR2_TABLE);

Parameters

Exceptions

Raises an error if DAD does not exist.

Usage Notes

If the DAD is not mapped to any virtual path, paths will be set to empty arrays.

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GET_ALL_GLOBAL_ATTRIBUTES Procedure

This procedure retrieves all global attributes and values. The outputs are 2 correlated index-by tables of the name/value pairs.

Syntax

DBMS_EPG.GET_ALL_GLOBAL_ATTRIBUTES (
   attr_names     OUT   NOCOPY  VARCHAR2_TABLE,
   attr_values    OUT   NOCOPY  VARCHAR2_TABLE);

Parameters

Usage Notes

If the gateway instance has no global attributes set, then attr_names and attr_values will be set to empty arrays.

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GET_DAD_ATTRIBUTE Function

This procedure retrieves the value of a DAD attribute.

Syntax

DBMS_EPG.GET_DAD_ATTRIBUTE (
   dad_name     IN  VARCHAR2,
   attr_name    IN  VARCHAR2)
 RETURN VARCHAR2;

Parameters

Return values

Returns the DAD attribute value. Returns NULL if attribute is unknown or has not been set.

Exceptions

Raises an error if DAD does not exist.

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GET_DAD_LIST Procedure

This procedure retrieves a list of all DADs for an Embedded Gateway instance.

Syntax

DBMS_EPG.GET_DAD_LIST (
   dad_names     OUT NOCOPY  VARCHAR2_TABLE);

Parameters

Usage Notes

If no DADs exist then dad_names will be set to an empty array.

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GET_GLOBAL_ATTRIBUTE Function

This function retrieves the value of a global attribute.

Syntax

DBMS_EPG.GET_GLOBAL_ATTRIBUTE (
   attr_name  IN  VARCHAR2)
 RETURN VARCHAR2;

Parameters

Return Values

Returns the global attribute value. Returns NULL if attribute has not been set or is not a valid attribute.

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MAP_DAD Procedure

This procedure maps a DAD to the specified virtual path. If the virtual path exists already, the old virtual-path mapping will be overridden.

Syntax

DBMS_EPG.MAP_DAD (
   dad_name  IN  VARCHAR2,
   path      IN  VARCHAR2);

Parameters

Exceptions

Raises and error if the DAD does not exist.

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SET_DAD_ATTRIBUTE Procedure

This procedure sets the value for a DAD.

Syntax

DBMS_EPG.SET_DAD_ATTRIBUTE (
   dad_name    IN  VARCHAR2,
   attr_name   IN  VARCHAR2,   attr_value  IN  VARCHAR2);

Parameters

Exceptions

Raises an error if DAD does not exist or the attribute is unknown.

Usage Notes

• If attr_name attribute has been set before, then the old value will be overwritten with the new attr_value argument.

• The embedded gateway assumes default values when the attributes are not set. The default values of the DAD attributes should be sufficient for most users of the embedded gateway. mod_plsql users should note the following

  • The PlsqlDatabasePassword attribute is not needed.

  • The PlsqlDatabaseConnectString attribute is not needed because the embedded gateway does not support logon to external databases.

Examples

DBMS_EPG.SET_DAD_ATTRIBUTE('HR', 'default-page', 'HRApp.home');

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SET_GLOBAL_ATTRIBUTE Procedure

This procedure sets the value of a global attribute.

Syntax

DBMS_EPG.SET_GLOBAL_ATTRIBUTE (
   attr_name    IN VARCHAR2,                     
   attr_value   IN VARCHAR2);

Parameters

Usage Notes

• The attribute name is case sensitive. The value may or may not be case-sensitive depending on the attribute.

• If attr_name attribute has been set before, then the old value will be overwritten with the new attr_value argument.

Exceptions

Raises an error if the attribute is unknown.

Examples

dbms_epg.set_global_attribute('max-parameters', '100');

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UNMAP_DAD Procedure

This procedure unmaps a DAD from the specified virtual path. If path is NULL, the procedure removes all virtual-path mappings for the DAD but keeps the DAD.

Syntax

DBMS_EPG.UNMAP_DAD (
   dad_name IN VARCHAR2,
   path     IN VARCHAR2 DEFAULT NULL);

Parameters

Usage Notes

Raises and error if the DAD does not exist.