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Oracle® Call Interface Programmer's Guide
12c Release 1 (12.1)

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Connect, Authorize, and Initialize Functions

Table 16-1 describes the OCI connect, authorize, and initialize functions that are described in this section.

Table 16-2 Connect, Authorize, and Initialize Functions  

Function Purpose

"OCIAppCtxClearAll()"

Clear all attribute-value information in a namespace of an application context

"OCIAppCtxSet()"

Set an attribute and its associated value in a namespace of an application context

"OCIConnectionPoolCreate()"

Initialize the connection pool

"OCIConnectionPoolDestroy()"

Destroy the connection pool

"OCIDBShutdown()"

Shut down Oracle Database

"OCIDBStartup()"

Start an Oracle Database instance

"OCIEnvCreate()"

Create and initialize an OCI environment handle

"OCIEnvNlsCreate()"

Create and initialize an environment handle for OCI functions to work under. Enable you to set character set ID and national character set ID at environment creation time.

"OCILogoff()"

Release a session that was retrieved using OCILogon2() or OCILogon()

"OCILogon()"

Simplify single-session logon

"OCILogon2()"

Create a logon session in various modes

"OCIServerAttach()"

Attach to a server; initialize server context handle

"OCIServerDetach()"

Detach from a server; uninitialize server context handle

"OCISessionBegin()"

Authenticate a user

"OCISessionEnd()"

Terminate a user session

"OCISessionGet()"

Get a session from a session pool

"OCISessionPoolCreate()"

Initialize a session pool

"OCISessionPoolDestroy()"

Destroy a session pool

"OCISessionRelease()"

Release a session

"OCITerminate()"

Detach from a shared memory subsystem


OCIAppCtxClearAll()

Purpose

Clears all attribute-value information in a namespace of an application context.

Syntax

sword OCIAppCtxClearAll ( void      *sesshndl,
                          void      *nsptr, 
                          ub4       nsptrlen,
                          OCIError  *errhp,
                          ub4       mode ;

Parameters

sesshndl (IN/OUT)

Pointer to a session handle.

nsptr (IN)

Pointer to the namespace string (currently only CLIENTCONTEXT).

nsptrlen (IN)

Length of the namespace string.

errhp (OUT)

An error handle that can be passed to OCIErrorGet().

mode (IN)

Mode (OCI_DEFAULT is the default).

Returns

Returns an error number.

Comments

This cleans up the context information on the server side during the next call to the server. This namespace information is cleared from the session handle after the information has been sent to the server and must be set up again if needed.

Related Functions

OCIAppCtxSet()

OCIAppCtxSet()

Purpose

Sets an attribute and its associated value in a namespace of an application context.

Syntax

sword OCIAppCtxSet ( void      *sesshndl,
                     void      *nsptr,
                     ub4       nsptrlen,
                     void      *attrptr,
                     ub4       attrptrlen,
                     void      *valueptr,
                     ub4       valueptrlen,
                     OCIError  *errhp, 
                     ub4       mode );

Parameters

sesshndl (IN/OUT)

Pointer to a session handle.

nsptr (IN)

Pointer to the namespace string (currently only CLIENTCONTEXT).

nsptrlen (IN)

Length of the namespace string.

attrptr (IN)

Pointer to the attribute string.

attrptrlen (IN)

The length of the string pointed to by attrptr.

valueptr (IN)

Pointer to the value string.

valueptrlen (IN)

The length of the string pointed to by valueptr.

errhp (OUT)

An error handle that can be passed to OCIErrorGet().

mode (IN)

Mode (OCI_DEFAULT is the default).

Returns

Returns an error number.

Comments

The information set on the session handle is sent to the server during the next call to the server.

This information is cleared from the session handle after the information has been sent to the server and must be set up again if needed.

Related Functions

OCIAppCtxClearAll()

OCIConnectionPoolCreate()

Purpose

Initializes the connection pool.

Syntax

sword OCIConnectionPoolCreate ( OCIEnv         *envhp,
                                OCIError       *errhp, 
                                OCICPool       *poolhp,
                                OraText        **poolName,
                                sb4            *poolNameLen,
                                const OraText  *dblink, 
                                sb4            dblinkLen,
                                ub4            connMin,
                                ub4            connMax,
                                ub4            connIncr,
                                const OraText  *poolUsername,
                                sb4            poolUserLen,
                                const OraText  *poolPassword,
                                sb4            poolPassLen,
                                ub4            mode );

Parameters

envhp (IN)

A pointer to the environment where the connection pool is to be created

errhp (IN/OUT)

An error handle that can be passed to OCIErrorGet().

poolhp (IN)

An allocated pool handle.

poolName (OUT)

The name of the connection pool connected to.

poolNameLen (OUT)

The length of the string pointed to by poolName.

dblink (IN)

Specifies the database (server) to connect to.

dblinkLen (IN)

The length of the string pointed to by dblink.

connMin (IN)

Specifies the minimum number of connections in the connection pool. Valid values are 0 and higher.

These connections are opened to the server by OCIConnectionPoolCreate(). After the connection pool is created, connections are opened only when necessary. Generally, this parameter should be set to the number of concurrent statements that the application is planning or expecting to run.

connMax (IN)

Specifies the maximum number of connections that can be opened to the database. After this value is reached, no more connections are opened. Valid values are 1 and higher.

connIncr (IN)

Allows the application to set the next increment for connections to be opened to the database if the current number of connections is less than connMax. Valid values are 0 and higher.

poolUsername (IN)

Connection pooling requires an implicit primary session. This attribute provides a user name for that session.

poolUserLen (IN)

The length of poolUsername.

poolPassword (IN)

The password for the user name poolUsername.

poolPassLen (IN)

The length of poolPassword.

mode (IN)

The modes supported are:

  • OCI_DEFAULT

  • OCI_CPOOL_REINITIALIZE

Ordinarily, OCIConnectionPoolCreate() is called with mode set to OCI_DEFAULT.

To change the pool attributes dynamically (for example, to change the connMin, connMax, and connIncr parameters), call OCIConnectionPoolCreate() with mode set to OCI_CPOOL_REINITIALIZE. When this is done, the other parameters are ignored.

Comments

The OUT parameters poolName and poolNameLen contain values to be used in subsequent OCIServerAttach() and OCILogon2() calls in place of the database name and the database name length arguments.

OCIConnectionPoolDestroy()

Purpose

Destroys the connection pool.

Syntax

sword OCIConnectionPoolDestroy ( OCICPool     *poolhp,
                                 OCIError     *errhp, 
                                 ub4          mode );

Parameters

poolhp (IN)

A pool handle for which a pool has been created.

errhp (IN/OUT)

An error handle that can be passed to OCIErrorGet().

mode (IN)

Currently, this function supports only the OCI_DEFAULT mode.

Related Functions

OCIConnectionPoolCreate()

OCIDBShutdown()

Purpose

Shuts down an Oracle Database instance.

Syntax

sword OCIDBShutdown ( OCISvcCtx     *svchp,
                      OCIError      *errhp,
                      OCIAdmin      *admhp,
                      ub4           mode);

Parameters

svchp (IN)

A handle to a service context. There must be a valid server handle and a valid user handle set in svchp.

errhp (IN/OUT)

An error handle that can be passed to OCIErrorGet() for diagnostic information when there is an error.

admhp (IN) - Optional

An instance administration handle. Currently not used; pass (OCIAdmin *)0.

mode (IN)

OCI_DEFAULT - Further connects are prohibited. Waits for users to disconnect from the database.

OCI_DBSHUTDOWN_TRANSACTIONAL - Further connects are prohibited and no new transactions are allowed. Waits for active transactions to complete.

OCI_DBSHUTDOWN_TRANSACTIONAL_LOCAL - Further connects are prohibited and no new transactions are allowed. Waits only for local transactions to complete.

OCI_DBSHUTDOWN_IMMEDIATE - Does not wait for current calls to complete or users to disconnect from the database. All uncommitted transactions are terminated and rolled back.

OCI_DBSHUTDOWN_FINAL - Shuts down the database. Should be used only in the second call to OCIDBShutdown() after the database is closed and dismounted.

OCI_DBSHUTDOWN_ABORT - Does not wait for current calls to complete or users to disconnect from the database. All uncommitted transactions are terminated and are not rolled back. This is the fastest possible way to shut down the database, but the next database startup may require instance recovery. Therefore, this option should be used only in unusual circumstances; for example, if a background process terminates abnormally.

Comments

To do a shut down, you must be connected to the database as SYSOPER or SYSDBA. You cannot be connected to a shared server through a dispatcher. When shutting down in any mode other than OCI_DBSHUTDOWN_ABORT, use the following procedure:

  1. Call OCIDBShutdown() in OCI_DEFAULT, OCI_DBSHUTDOWN_TRANSACTIONAL, OCI_DBSHUTDOWN_TRANSACTIONAL_LOCAL, or OCI_DBSHUTDOWN_IMMEDIATE mode to prohibit further connects.

  2. Issue the necessary ALTER DATABASE commands to close and dismount the database.

  3. Call OCIDBShutdown() in OCI_DBSHUTDOWN_FINAL mode to shut down the instance.

Related Functions

OCIAttrSet(), OCIDBStartup()

OCIDBStartup()

Purpose

Starts an Oracle Database instance.

Syntax

sword OCIDBStartup ( OCISvcCtx     *svchp,
                     OCIError      *errhp,
                     OCIAdmin      *admhp,
                     ub4           mode,
                     ub4           flags);

Parameters

svchp (IN)

A handle to a service context. There must be a valid server handle and user handle set in svchp.

errhp (IN/OUT)

An error handle that can be passed to OCIErrorGet() for diagnostic information when there is an error.

admhp (IN) - Optional

An instance administration handle. Use to pass additional arguments to the startup call, or pass (OCIAdmin *)0 if you do not set OCI_ATTR_ADMIN_PFILE.

mode (IN)

OCI_DEFAULT - This is the only supported mode. It starts the instance, but does not mount or open the database. Same as STARTUP NOMOUNT.

flags (IN)

OCI_DEFAULT - Allows database access to all users.

OCI_DBSTARTUPFLAG_RESTRICT - Allows database access only to users with both the CREATE SESSION and RESTRICTED SESSION privileges (normally, the DBA).

OCI_DBSTARTUPFLAG_FORCE - Shuts down a running instance (if there is any) using ABORT before starting a new one. This mode should be used only in unusual circumstances.

Comments

You must be connected to the database as SYSOPER or SYSDBA in OCI_PRELIM_AUTH mode. You cannot be connected to a shared server through a dispatcher (that is, when you restart a running instance with OCI_DBSTARTUPFLAG_FORCE). To use a client-side parameter file (pfile), OCI_ATTR_ADMIN_PFILE must be set in the administration handle; otherwise, a server-side parameter file (spfile) is used. A call to OCIDBStartup() starts one instance on the server.

OCIEnvCreate()

Purpose

Creates and initializes an environment handle for OCI functions to work under.

Syntax

sword OCIEnvCreate   ( OCIEnv        **envhpp,
                       ub4           mode,
                       const void    *ctxp,
                       const void    *(*malocfp)
                                     (void  *ctxp,
                                      size_t size),
                       const void    *(*ralocfp)
                                     (void  *ctxp,
                                      void  *memptr,
                                      size_t newsize),
                       const void    (*mfreefp)
                                     (void  *ctxp,
                                      void  *memptr))
                       size_t         xtramemsz,
                       void           **usrmempp );

Parameters

envhpp (OUT)

A pointer to an environment handle whose encoding setting is specified by mode. The setting is inherited by statement handles derived from envhpp.

mode (IN)

Specifies initialization of the mode. Valid modes are:

  • OCI_DEFAULT - The default value, which is non-UTF-16 encoding.

  • OCI_THREADED - Uses threaded environment. Internal data structures not exposed to the user are protected from concurrent accesses by multiple threads.

  • OCI_OBJECT - Uses object features.

  • OCI_EVENTS - Uses publish-subscribe notifications.

  • OCI_NO_UCB - Suppresses the calling of the dynamic callback routine OCIEnvCallback(). The default behavior is to allow calling of OCIEnvCallback() when the environment is created.

  • OCI_ENV_NO_MUTEX - No mutual exclusion (mutex) locking occurs in this mode. All OCI calls done on the environment handle, or on handles derived from the environment handle, must be serialized. OCI_THREADED must also be specified when OCI_ENV_NO_MUTEX is specified.

  • OCI_SUPPRESS_NLS_VALIDATION - Suppresses NLS character validation; NLS character validation suppression is on by default beginning with Oracle Database 11g Release 1 (11.1). Use OCI_ENABLE_NLS_VALIDATION to enable NLS character validation. See Comments for more information.

  • OCI_NEW_LENGTH_SEMANTICS - Byte-length semantics is used consistently for all handles, regardless of character sets.

  • OCI_NCHAR_LITERAL_REPLACE_ON - Turns on N' substitution.

  • OCI_NCHAR_LITERAL_REPLACE_OFF - Turns off N' substitution. If neither this mode nor OCI_NCHAR_LITERAL_REPLACE_ON is used, the substitution is determined by the environment variable ORA_NCHAR_LITERAL_REPLACE, which can be set to TRUE or FALSE. When it is set to TRUE, the replacement is turned on; otherwise it is turned off, which is the default setting in OCI.

  • OCI_ENABLE_NLS_VALIDATION - Enables NLS character validation. See Comments for more information.

ctxp (IN)

Specifies the user-defined context for the memory callback routines.

malocfp (IN)

Specifies the user-defined memory allocation function. If mode is OCI_THREADED, this memory allocation routine must be thread-safe.

ctxp (IN)

Specifies the context pointer for the user-defined memory allocation function.

size (IN)

Specifies the size of memory to be allocated by the user-defined memory allocation function.

ralocfp (IN)

Specifies the user-defined memory reallocation function. If the mode is OCI_THREADED, this memory allocation routine must be thread-safe.

ctxp (IN)

Specifies the context pointer for the user-defined memory reallocation function.

memptr (IN)

Pointer to memory block.

newsize (IN)

Specifies the new size of memory to be allocated.

mfreefp (IN)

Specifies the user-defined memory free function. If the mode is OCI_THREADED, this memory free routine must be thread-safe.

ctxp (IN)

Specifies the context pointer for the user-defined memory free function.

memptr (IN)

Pointer to memory to be freed.

xtramemsz (IN)

Specifies the amount of user memory to be allocated for the duration of the environment.

usrmempp (OUT)

Returns a pointer to the user memory of size xtramemsz allocated by the call for the user.

Comments

This call creates an environment for all the OCI calls using the modes specified by the user.

Note:

This call should be invoked before any other OCI call and should be used instead of the OCIInitialize() call.

This call returns an environment handle, which is then used by the remaining OCI functions. There can be multiple environments in OCI, each with its own environment modes. This function also performs any process level initialization if required by any mode. For example, if you want to initialize an environment as OCI_THREADED, then all libraries that are used by OCI are also initialized in the threaded mode.

If N' substitution is turned on, the OCIStmtPrepare() or OCIStmtPrepare2() function performs the N' substitution on the SQL text and stores the resulting SQL text in the statement handle. Thus, if the application uses OCI_ATTR_STATEMENT to retrieve the SQL text from the OCI statement handle, the modified SQL text, instead of the original SQL text, is returned.

To turn on N' substitution in ksh shell:

export ORA_NCHAR_LITERAL_REPLACE=TRUE

To turn on N' substitution in csh shell:

setenv ORA_NCHAR_LITERAL_REPLACE TRUE

If a remote database is of a release before 10.2, N' substitution is not performed.

If you are writing a DLL or a shared library using the OCI library, then use this call instead of the deprecated OCIInitialize() call.

See Also:

"User Memory Allocation" for more information about the xtramemsz parameter and user memory allocation

Regarding OCI_SUPPRESS_NLS_VALIDATION and OCI_ENABLE_NLS_VALIDATION modes, by default, when client and server character sets are identical, and client and server releases are both Oracle Database 11g Release 1 (11.1) or higher, OCI does not validate character data in the interest of better performance. This means that if the application inserts a character string with partial multibyte characters (for example, at the end of a bind variable), then such strings could get persisted in the database as is.

Note that if either the client or the server release is older than Oracle Database 11g Release 1 (11.1), then OCI does not allow partial characters.

The OCI_ENABLE_NLS_VALIDATION mode, which was the default until Oracle Database 10g Release 2 (10.2), ensures that partial multibyte characters are not persisted in the database (when client and server character sets are identical). If the application can produce partial multibyte characters, and if the application can run in an environment where the client and server character sets are identical, then Oracle recommends using the OCI_ENABLE_NLS_VALIDATION mode explicitly in order to ensure that such partial characters get stripped out.

Example

Example 16-1 Creating a Thread-Safe OCI Environment with N' Substitution Turned On

OCIEnv *envhp;
...
/* Create a thread-safe OCI environment with N' substitution turned on.  */
if(OCIEnvCreate((OCIEnv **)&envhp,
         (ub4)OCI_THREADED | OCI_NCHAR_LITERAL_REPLACE_ON,
         (void  *)0, (void  * (*)(void  *, size_t))0,
         (void  * (*)(void  *, void  *, size_t))0,
         (void (*)(void  *, void  *))0,
         (size_t)0, (void  **)0))
{
  printf("Failed: OCIEnvCreate()\n");
  return 1;
}
...

OCIEnvNlsCreate()

Purpose

Creates and initializes an environment handle for OCI functions to work under. It is an enhanced version of the OCIEnvCreate() function.

Syntax

sword OCIEnvNlsCreate   ( OCIEnv        **envhpp,
                          ub4           mode,
                          void          *ctxp,
                          void          *(*malocfp)
                                             (void  *ctxp,
                                              size_t size),
                          void          *(*ralocfp)
                                             (void  *ctxp,
                                              void  *memptr,
                                              size_t newsize),
                          void          (*mfreefp)
                                             (void  *ctxp,
                                              void  *memptr))
                          size_t        xtramemsz,
                          void          **usrmempp
                          ub2           charset,
                          ub2           ncharset );

Parameters

envhpp (OUT)

A pointer to an environment handle whose encoding setting is specified by mode. The setting is inherited by statement handles derived from envhpp.

mode (IN)

Specifies initialization of the mode. Valid modes are:

  • OCI_DEFAULT - The default value, which is non-UTF-16 encoding.

  • OCI_THREADED - Uses threaded environment. Internal data structures not exposed to the user are protected from concurrent accesses by multiple threads.

  • OCI_OBJECT - Uses object features.

  • OCI_EVENTS - Uses publish-subscribe notifications.

  • OCI_NO_UCB - Suppresses the calling of the dynamic callback routine OCIEnvCallback(). The default behavior is to allow calling of OCIEnvCallback() when the environment is created.

  • OCI_ENV_NO_MUTEX - No mutual exclusion (mutex) locking occurs in this mode. All OCI calls done on the environment handle, or on handles derived from the environment handle, must be serialized. OCI_THREADED must also be specified when OCI_ENV_NO_MUTEX is specified.

  • OCI_SUPPRESS_NLS_VALIDATION - Suppresses NLS character validation; NLS character validation suppression is on by default beginning with Oracle Database 11g Release 1 (11.1). Use OCI_ENABLE_NLS_VALIDATION to enable NLS character validation. See Comments for more information.

  • OCI_NCHAR_LITERAL_REPLACE_ON - Turns on N' substitution.

  • OCI_NCHAR_LITERAL_REPLACE_OFF - Turns off N' substitution. If neither this mode nor OCI_NCHAR_LITERAL_REPLACE_ON is used, the substitution is determined by the environment variable ORA_NCHAR_LITERAL_REPLACE, which can be set to TRUE or FALSE. When it is set to TRUE, the replacement is turned on; otherwise it is turned off, the default setting in OCI.

  • OCI_ENABLE_NLS_VALIDATION - Enables NLS character validation. See Comments for more information.

ctxp (IN)

Specifies the user-defined context for the memory callback routines.

malocfp (IN)

Specifies the user-defined memory allocation function. If mode is OCI_THREADED, this memory allocation routine must be thread-safe.

ctxp (IN)

Specifies the context pointer for the user-defined memory allocation function.

size (IN)

Specifies the size of memory to be allocated by the user-defined memory allocation function.

ralocfp (IN)

Specifies the user-defined memory reallocation function. If the mode is OCI_THREADED, this memory allocation routine must be thread-safe.

ctxp (IN)

Specifies the context pointer for the user-defined memory reallocation function.

memptr (IN)

Pointer to memory block.

newsize (IN)

Specifies the new size of memory to be allocated.

mfreefp (IN)

Specifies the user-defined memory free function. If the mode is OCI_THREADED, this memory free routine must be thread-safe.

ctxp (IN)

Specifies the context pointer for the user-defined memory free function.

memptr (IN)

Pointer to memory to be freed.

xtramemsz (IN)

Specifies the amount of user memory to be allocated for the duration of the environment.

usrmempp (OUT)

Returns a pointer to the user memory of size xtramemsz allocated by the call for the user.

charset (IN)

The client-side character set for the current environment handle. If it is 0, the NLS_LANG setting is used. OCI_UTF16ID is a valid setting; it is used by the metadata and the CHAR data.

ncharset (IN)

The client-side national character set for the current environment handle. If it is 0, NLS_NCHAR setting is used. OCI_UTF16ID is a valid setting; it is used by the NCHAR data.

Returns

OCI_SUCCESS - Environment handle has been successfully created.

OCI_ERROR - An error occurred.

Comments

This call creates an environment for all the OCI calls using the modes you specify.

After you use OCIEnvNlsCreate() to create the environment handle, the actual lengths and returned lengths of bind and define handles are always expressed in number of bytes. This applies to the following calls:

This function enables you to set charset and ncharset IDs at environment creation time. It is an enhanced version of the OCIEnvCreate() function.

This function sets nonzero charset and ncharset as client-side database and national character sets, replacing the ones specified by NLS_LANG and NLS_NCHAR. When charset and ncharset are 0, the function behaves exactly the same as OCIEnvCreate(). Specifically, charset controls the encoding for metadata and data with implicit form attribute, and ncharset controls the encoding for data with SQLCS_NCHAR form attribute.

Although OCI_UTF16ID can be set by OCIEnvNlsCreate(), it cannot be set in NLS_LANG or NLS_NCHAR. To access the character set IDs in NLS_LANG and NLS_NCHAR, use OCINlsEnvironmentVariableGet().

This call returns an environment handle, which is then used by the remaining OCI functions. There can be multiple environments in OCI, each with its own environment modes. This function also performs any process level initialization if required by any mode. For example, if you want to initialize an environment as OCI_THREADED, then all libraries that are used by OCI are also initialized in the threaded mode.

If N' substitution is turned on, the OCIStmtPrepare() or OCIStmtPrepare2() function performs the N' substitution on the SQL text and stores the resulting SQL text in the statement handle. Thus, if the application uses OCI_ATTR_STATEMENT to retrieve the SQL text from the OCI statement handle, the modified SQL text, instead of the original SQL text, is returned.

To turn on N' substitution in ksh shell:

export ORA_NCHAR_LITERAL_REPLACE=TRUE

To turn on N' substitution in csh shell:

setenv ORA_NCHAR_LITERAL_REPLACE TRUE

If a remote database is of a release before 10.2, N' substitution is not performed.

If you are writing a DLL or a shared library using the OCI library, then use this call instead of the deprecated OCIInitialize() call.

See Also:

Regarding OCI_SUPPRESS_NLS_VALIDATION and OCI_ENABLE_NLS_VALIDATION modes, by default, when client and server character sets are identical, and client and server releases are both Oracle Database 11g Release 1 (11.1) or higher, OCI does not validate character data in the interest of better performance. This means that if the application inserts a character string with partial multibyte characters (for example, at the end of a bind variable), then such strings could get persisted in the database as is.

Note that if either the client or the server release is older than Oracle Database 11g Release 1 (11.1), then OCI does not allow partial characters.

The OCI_ENABLE_NLS_VALIDATION mode, which was the default until Oracle Database 10g Release 2 (10.2), ensures that partial multibyte characters are not persisted in the database (when client and server character sets are identical). If the application can produce partial multibyte characters, and if the application can run in an environment where the client and server character sets are identical, then Oracle recommends using the OCI_ENABLE_NLS_VALIDATION mode explicitly in order to ensure that such partial characters get stripped out.

OCILogoff()

Purpose

Releases a session that was retrieved using OCILogon2() or OCILogon().

Syntax

sword OCILogoff ( OCISvcCtx      *svchp
                  OCIError       *errhp );

Parameters

svchp (IN)

The service context handle that was used in the call to OCILogon() or OCILogon2().

errhp (IN/OUT)

An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.

Comments

This function is used to release a session that was retrieved using OCILogon2() or OCILogon(). If OCILogon() was used, then this function terminates the connection and session. If OCILogon2() was used, then the exact behavior of this call is determined by the mode in which the corresponding OCILogon2() function was called. In the default case, this function closes the session or connection. For connection pooling, it closes the session and returns the connection to the pool. For session pooling, it returns the session or connection pair to the pool.

See Also:

"Application Initialization, Connection, and Session Creation" for more information about logging on and off in an application

Related Functions

OCILogon(), OCILogon2()

OCILogon()

Purpose

Creates a simple logon session.

Syntax

sword OCILogon ( OCIEnv          *envhp,
                 OCIError        *errhp,
                 OCISvcCtx       **svchp,
                 const OraText   *username,
                 ub4             uname_len,
                 const OraText   *password,
                 ub4             passwd_len,
                 const OraText   *dbname,
                 ub4             dbname_len );

Parameters

envhp (IN)

The OCI environment handle.

errhp (IN/OUT)

An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.

svchp (IN/OUT)

The service context pointer.

username (IN)

The user name. Must be in the encoding specified by the charset parameter of a previous call to OCIEnvNlsCreate().

uname_len (IN)

The length of username, in number of bytes, regardless of the encoding.

password (IN)

The user's password. Must be in the encoding specified by the charset parameter of a previous call to OCIEnvNlsCreate().

passwd_len (IN)

The length of password, in number of bytes, regardless of the encoding.

dbname (IN)

The name of the database to connect to. Must be in the encoding specified by the charset parameter of a previous call to OCIEnvNlsCreate().

dbname_len (IN)

The length of dbname, in number of bytes, regardless of the encoding.

Comments

This function is used to create a simple logon session for an application.

Note:

Users requiring more complex sessions, such as TP monitor applications, should see "Application Initialization, Connection, and Session Creation".

This call allocates the service context handles that are passed to it. This call also implicitly allocates server and user session handles associated with the session. These handles can be retrieved by calling OCIArrayDescriptorAlloc() on the service context handle.

Related Functions

OCILogoff()

OCILogon2()

Purpose

Gets a session. This session may be a new one with a new underlying connection, or one that is started over a virtual connection from an existing connection pool, or one from an existing session pool. The mode that the function is called with determines its behavior.

Syntax

sword OCILogon2 ( OCIEnv          *envhp,
                  OCIError        *errhp,
                  OCISvcCtx       **svchp,
                  const OraText   *username,
                  ub4             uname_len,
                  const OraText   *password,
                  ub4             passwd_len,
                  const OraText   *dbname,
                  ub4             dbname_len );
                  ub4             mode );

Parameters

envhp (IN)

The OCI environment handle. For connection pooling and session pooling, this must be the one that the respective pool was created in.

errhp (IN/OUT)

An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.

svchp (IN/OUT)

Address of an OCI service context pointer. This is filled with a server and session handle.

In the default case, a new session and server handle is allocated, the connection and session are started, and the service context is populated with these handles.

For connection pooling, a new session handle is allocated, and the session is started over a virtual connection from the connection pool.

For session pooling, the service context is populated with an existing session or server handle pair from the session pool.

Note that you must not change any attributes of the server and user or session handles associated with the service context pointer. Doing so results in an error being returned by the OCIAttrSet() call.

The only attribute of the service context that can be altered is OCI_ATTR_STMTCACHESIZE.

username (IN)

The user name used to authenticate the session. Must be in the encoding specified by the charset parameter of a previous call to OCIEnvNlsCreate().

uname_len (IN)

The length of username, in number of bytes, regardless of the encoding.

password (IN)

The user's password. For connection pooling, if this parameter is NULL then OCILogon2() assumes that the logon is for a proxy user. It implicitly creates a proxy connection in such a case, using the pool user to authenticate the proxy user. Must be in the encoding specified by the charset parameter of a previous call to OCIEnvNlsCreate().

passwd_len (IN)

The length of password, in number of bytes, regardless of the encoding.

dbname (IN)

For the default case, this indicates the connect string to use to connect to the Oracle Database.

For connection pooling, this indicates the connection pool from which to retrieve the virtual connection to start the session. This value is returned by the OCIConnectionPoolCreate() call.

For session pooling, it indicates the pool to get the session from. It is returned by the OCISessionPoolCreate() call.

The dbname must be in the encoding specified by the charset parameter of a previous call to OCIEnvNlsCreate().

dbname_len (IN)

The length of dbname. For session pooling and connection pooling, this value is returned by the OCISessionPoolCreate() or OCIConnectionPoolCreate() call respectively.

mode (IN)

The values accepted are:

  • OCI_DEFAULT

  • OCI_LOGON2_CPOOL

  • OCI_LOGON2_SPOOL

  • OCI_LOGON2_STMTCACHE

  • OCI_LOGON2_PROXY

For the default (nonpooling case), the following modes are valid:

OCI_DEFAULT - Equivalent to calling OCILogon().

OCI_LOGON2_STMTCACHE - Enable statement caching.

For connection pooling, the following modes are valid:

OCI_LOGON2_CPOOL or OCI_CPOOL - This must be set to use connection pooling.

OCI_LOGON2_STMTCACHE - Enable statement caching.

To use proxy authentication for connection pooling, the password must be set to NULL. You are then given a session that is authenticated by the user name provided in the OCILogon2() call, through the proxy credentials supplied in the OCIConnectionPoolCreate() call.

For session pooling, the following modes are valid:

OCI_LOGON2_SPOOL - This must be set to use session pooling.

OCI_LOGON2_STMTCACHE - Enable statement caching.

OCI_LOGON2_PROXY - Use proxy authentication. You are given a session that is authenticated by the user name provided in the OCILogon2() call, through the proxy credentials supplied in the OCISessionPoolCreate() call.

Comments

None.

OCIServerAttach()

Purpose

Creates an access path to a data source for OCI operations.

Syntax

sword OCIServerAttach ( OCIServer     *srvhp,
                        OCIError      *errhp,
                        const OraText *dblink,
                        sb4           dblink_len,
                        ub4           mode );

Parameters

srvhp (IN/OUT)

An uninitialized server handle, which is initialized by this call. Passing in an initialized server handle causes an error.

errhp (IN/OUT)

An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.

dblink (IN)

Specifies the database server to use. This parameter points to a character string that specifies a connect string or a service point. If the connect string is NULL, then this call attaches to the default host. The string itself could be in UTF-16 encoding mode or not, depending on the mode or the setting in application's environment handle. The length of dblink is specified in dblink_len. The dblink pointer may be freed by the caller on return.

The name of the connection pool to connect to when mode = OCI_CPOOL. This must be the same as the poolName parameter of the connection pool created by OCIConnectionPoolCreate(). Must be in the encoding specified by the charset parameter of a previous call to OCIEnvNlsCreate().

dblink_len (IN)

The length of the string pointed to by dblink. For a valid connect string name or alias, dblink_len must be nonzero. Its value is in number of bytes.

The length of poolName, in number of bytes, regardless of the encoding, when mode = OCI_CPOOL.

mode (IN)

Specifies the various modes of operation. The valid modes are:

  • OCI_DEFAULT - For encoding, this value tells the server handle to use the setting in the environment handle.

  • OCI_CPOOL - Use connection pooling.

Because an attached server handle can be set for any connection session handle, the mode value here does not contribute to any session handle.

Comments

This call is used to create an association between an OCI application and a particular server.

This call assumes that OCIConnectionPoolCreate() has been called, giving poolName, when connection pooling is in effect.

This call initializes a server context handle, which must have been previously allocated with a call to OCIHandleAlloc(). The server context handle initialized by this call can be associated with a service context through a call to OCIAttrSet(). After that association has been made, OCI operations can be performed against the server.

If an application is operating against multiple servers, multiple server context handles can be maintained. OCI operations are performed against whichever server context is currently associated with the service context.

When OCIServerAttach() is successfully completed, an Oracle Database shadow process is started. OCISessionEnd() and OCIServerDetach() should be called to clean up the Oracle Database shadow process. Otherwise, the shadow processes accumulate and cause the Linux or UNIX system to run out of processes. If the database is restarted and there are not enough processes, the database may not start up.

Example

Example 16-2 demonstrates the use of OCIServerAttach(). This code segment allocates the server handle, makes the attach call, allocates the service context handle, and then sets the server context into it.

Example 16-2 Using the OCIServerAttach() Call

OCIHandleAlloc( (void  *) envhp, (void  **) &srvhp, (ub4)
     OCI_HTYPE_SERVER, 0, (void  **) 0);
OCIServerAttach( srvhp, errhp, (text *) 0, (sb4) 0, (ub4) OCI_DEFAULT);
OCIHandleAlloc( (void  *) envhp, (void  **) &svchp, (ub4)
     OCI_HTYPE_SVCCTX, 0, (void  **) 0);
/* set attribute server context in the service context */
OCIAttrSet( (void  *) svchp, (ub4) OCI_HTYPE_SVCCTX, (void  *) srvhp,
     (ub4) 0, (ub4) OCI_ATTR_SERVER, (OCIError *) errhp);

Related Functions

OCIServerDetach()

OCIServerDetach()

Purpose

Deletes an access path to a data source for OCI operations.

Syntax

sword OCIServerDetach ( OCIServer   *srvhp,
                        OCIError    *errhp,
                        ub4         mode ); 

Parameters

srvhp (IN)

A handle to an initialized server context, which is reset to an uninitialized state. The handle is not deallocated.

errhp (IN/OUT)

An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.

mode (IN)

Specifies the various modes of operation. The only valid mode is OCI_DEFAULT for the default mode.

Comments

This call deletes an access path a to data source for OCI operations. The access path was established by a call to OCIServerAttach().

Related Functions

OCIServerAttach()

OCISessionBegin()

Purpose

Creates a user session and begins a user session for a given server.

Syntax

sword OCISessionBegin ( OCISvcCtx     *svchp,
                        OCIError      *errhp,
                        OCISession    *usrhp,
                        ub4           credt,
                        ub4           mode );

Parameters

svchp (IN)

A handle to a service context. There must be a valid server handle set in svchp.

errhp (IN)

An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.

usrhp (IN/OUT)

A handle to a user session context, which is initialized by this call.

credt (IN)

Specifies the type of credentials to use for establishing the user session. Valid values for credt are:

  • OCI_CRED_RDBMS - Authenticate using a database user name and password pair as credentials. The attributes OCI_ATTR_USERNAME and OCI_ATTR_PASSWORD should be set on the user session context before this call.

  • OCI_CRED_EXT - Authenticate using external credentials. No user name or password is provided.

mode (IN)

Specifies the various modes of operation. Valid modes are:

  • OCI_DEFAULT - In this mode, the user session context returned can only ever be set with the server context specified in svchp. For encoding, the server handle uses the setting in the environment handle.

  • OCI_MIGRATE - In this mode, the new user session context can be set in a service handle with a different server handle. This mode establishes the user session context. To create a migratable session, the service handle must already be set with a nonmigratable user session, which becomes the "creator" session of the migratable session. That is, a migratable session must have a nonmigratable parent session.

    OCI_MIGRATE should not be used when the session uses connection pool underneath. The session migration and multiplexing happens transparently to the user.

  • OCI_SYSDBA - In this mode, you are authenticated for SYSDBA access.

  • OCI_SYSOPER - In this mode, you are authenticated for SYSOPER access.

  • OCI_PRELIM_AUTH - This mode can only be used with OCI_SYSDBA or OCI_SYSOPER to authenticate for certain administration tasks.

  • OCI_STMT_CACHE - Enables statement caching with default size on the given service handle. It is optional to pass this mode if the application is going to explicitly set the size later using OCI_ATTR_STMTCACHESIZE on that service handle.

Comments

The OCISessionBegin() call is used to authenticate a user against the server set in the service context handle.

Note:

Check for any errors returned when trying to start a session. For example, if the password for the account has expired, an ORA-28001 error is returned.

For release 8.1 or later, OCISessionBegin() must be called for any given server handle before requests can be made against it. OCISessionBegin() only supports authenticating the user for access to the Oracle database specified by the server handle in the service context. In other words, after OCIServerAttach() is called to initialize a server handle, OCISessionBegin() must be called to authenticate the user for that given server.

When using Unicode, when the mode or the environment handle has the appropriate setting, the user name and password that have been set in the session handle usrhp should be in Unicode. Before calling this function to start a session with a user name and password, you must have called OCIAttrSet() to set these two Unicode strings into the session handle with corresponding length in bytes, because OCIAttrSet() only takes void pointers. The string buffers then are interpreted by OCISessionBegin().

When OCISessionBegin() is called for the first time for a given server handle, the user session may not be created in migratable (OCI_MIGRATE) mode.

After OCISessionBegin() has been called for a server handle, the application may call OCISessionBegin() again to initialize another user session handle with different (or the same) credentials and different (or the same) operation modes. If an application wants to authenticate a user in OCI_MIGRATE mode, the service handle must be associated with a nonmigratable user handle. The user ID of that user handle becomes the ownership ID of the migratable user session. Every migratable session must have a nonmigratable parent session.

If the OCI_MIGRATE mode is not specified, then the user session context can only be used with the same server handle set in svchp. If the OCI_MIGRATE mode is specified, then the user authentication can be set with different server handles. However, the user session context can only be used with server handles that resolve to the same database instance. Security checking is done during session switching. A session can migrate to another process only if there is a nonmigratable session currently connected to that process whose userid is the same as that of the creator's userid or its own userid.

Do not set the OCI_MIGRATE flag in the call to OCISessionBegin() when the virtual server handle points to a connection pool (OCIServerAttach() called with mode set to OCI_CPOOL). Oracle Database supports passing this flag only for compatibility reasons. Do not use the OCI_MIGRATE flag, as the perception that you get when using a connection pool is of sessions having their own dedicated (virtual) connections that are transparently multiplexed onto real connections.

OCI_SYSDBA, OCI_SYSOPER, and OCI_PRELIM_AUTH can only be used with a primary user session context.

To provide credentials for a call to OCISessionBegin(), two methods are supported. The first method is to provide a valid user name and password pair for database authentication in the user session handle passed to OCISessionBegin(). This involves using OCIAttrSet() to set the OCI_ATTR_USERNAME and OCI_ATTR_PASSWORD attributes on the user session handle. Then OCISessionBegin() is called with OCI_CRED_RDBMS.

Note:

When the user session handle is terminated using OCISessionEnd(), the user name and password attributes remain unchanged and thus can be reused in a future call to OCISessionBegin(). Otherwise, they must be reset to new values before the next OCISessionBegin() call.

The second method is to use external credentials. No attributes need to be set on the user session handle before calling OCISessionBegin(). The credential type is OCI_CRED_EXT. This is equivalent to the Oracle7 'connect /' syntax. If values have been set for OCI_ATTR_USERNAME and OCI_ATTR_PASSWORD, then these are ignored if OCI_CRED_EXT is used.

Another way of setting credentials is to use the session ID of an authenticated user with the OCI_MIGSESSION attribute. This ID can be extracted from the session handle of an authenticated user using the OCIAttrGet() call.

Example

Example 16-3 demonstrates the use of OCISessionBegin(). This code segment allocates the user session handle, sets the user name and password attributes, calls OCISessionBegin(), and then sets the user session into the service context.

Example 16-3 Using the OCISessionBegin() Call

/* allocate a user session handle */
OCIHandleAlloc((void  *)envhp, (void  **)&usrhp, (ub4)
     OCI_HTYPE_SESSION, (size_t) 0, (void  **) 0);
OCIAttrSet((void  *)usrhp, (ub4)OCI_HTYPE_SESSION, (void  *)"hr",
     (ub4)strlen("hr"), OCI_ATTR_USERNAME, errhp);
OCIAttrSet((void  *)usrhp, (ub4)OCI_HTYPE_SESSION, (void  *)"hr",
     (ub4)strlen("hr"), OCI_ATTR_PASSWORD, errhp);
checkerr(errhp, OCISessionBegin (svchp, errhp, usrhp, OCI_CRED_RDBMS,
     OCI_DEFAULT));
OCIAttrSet((void  *)svchp, (ub4)OCI_HTYPE_SVCCTX, (void  *)usrhp,
     (ub4)0, OCI_ATTR_SESSION, errhp);

Related Functions

OCISessionEnd()

OCISessionEnd()

Purpose

Terminates a user session context created by OCISessionBegin()

Syntax

sword OCISessionEnd ( OCISvcCtx       *svchp,
                      OCIError        *errhp,
                      OCISession      *usrhp,
                      ub4             mode );

Parameters

svchp (IN/OUT)

The service context handle. There must be a valid server handle and user session handle associated with svchp.

errhp (IN/OUT)

An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.

usrhp (IN)

Deauthenticate this user. If this parameter is passed as NULL, the user in the service context handle is deauthenticated.

mode (IN)

The only valid mode is OCI_DEFAULT.

Comments

The user security context associated with the service context is invalidated by this call. Storage for the user session context is not freed. The transaction specified by the service context is implicitly committed. The transaction handle, if explicitly allocated, may be freed if it is not being used. Resources allocated on the server for this user are freed. The user session handle can be reused in a new call to OCISessionBegin().

Related Functions

OCISessionBegin()

OCISessionGet()

Purpose

Gets a session. This session may be a new one with a new underlying connection, or one that is started over a virtual connection from an existing connection pool, or one from an existing session pool. The mode that the function is called with determines its behavior.

Syntax

sword OCISessionGet ( OCIenv            *envhp,
                      OCIError          *errhp,
                      OCISvcCtx         **svchp,
                      OCIAuthInfo       *authInfop,
                      OraText           *dbName,
                      ub4               dbName_len,
                      const OraText     *tagInfo,
                      ub4               tagInfo_len,
                      OraText           **retTagInfo,
                      ub4               *retTagInfo_len,
                      boolean           *found,
                      ub4               mode );

Parameters

envhp (IN/OUT)

OCI environment handle. For connection pooling and session pooling, this should be the one that the respective pool was created in.

errhp (IN/OUT)

OCI error handle.

svchp (OUT)

Address of an OCI service context pointer. This is filled with a server and session handle.

In the default case, a new session and server handle are allocated, the connection and session are started, and the service context is populated with these handles.

For connection pooling, a new session handle is allocated, and the session is started over a virtual connection from the connection pool.

For session pooling, the service context is populated with an existing session and server handle pair from the session pool.

Do not change any attributes of the server and user and session handles associated with the service context pointer. Doing so results in an error being returned by the OCIAttrSet() call.

The only attribute of the service context that can be altered is OCI_ATTR_STMTCACHESIZE.

authInfop (IN)

Authentication information handle to be used while getting the session.

In the default and connection pooling cases, this handle can take all the attributes of the session handle.

For session pooling, the authentication information handle is considered only if the session pool mode is not set to OCI_SPC_HOMOGENEOUS.

The attributes that can be set on the OCIAuthInfo handle can be categorized into pre-session-creation attributes and post-session-creation attributes. The pre-session-creation attributes are:

Pre-session-creation attributes

Pre-session-creation attributes are those OCI attributes that must be specified before a session is created. These attributes are used to create a session and cannot be changed after a session is created. The pre-session creation attributes are:

OCI_ATTR_USERNAME

OCI_ATTR_PASSWORD

OCI_ATTR_CONNECTION_CLASS

OCI_ATTR_PURITY

OCI_ATTR_PROXY_CREDENTIALS

OCI_ATTR_DISTINGUISHED_NAME

OCI_ATTR_CERTIFICATE

OCI_ATTR_INITIAL_CLIENT_ROLES

OCI_ATTR_APPCTX_SIZE

OCI_ATTR_EDITION

OCI_ATTR_DRIVER_NAME

Post-session-creation attributes

Post-session-creation attributes are those that can be specified after a session is created. They can be changed freely after a session is created as many times as desired. The following attributes can be set on the OCISession handle after the session has been created:

OCI_ATTR_CLIENT_IDENTIFIER

OCI_ATTR_CURRENT_SCHEMA

OCI_ATTR_MODULE

OCI_ATTR_ACTION

OCI_ATTR_DBOP

OCI_ATTR_CLIENT_INFO

OCI_ATTR_COLLECT_CALL_TIME

OCI_ATTR_DEFAULT_LOBPREFETCH_SIZE

OCI_ATTR_SESSION_STATE

See Also:

dbName (IN)

For the default case, this indicates the connect string to use to connect to the Oracle database.

For connection pooling, it indicates the connection pool to retrieve the virtual connection from, to start the session. This value is returned by the OCIConnectionPoolCreate() call.

For session pooling, it indicates the pool to get the session from. It is returned by the OCISessionPoolCreate() call.

dbName_len (IN)

The length of dbName. For session pooling and connection pooling, this value is returned by the call to OCISessionPoolCreate() or OCIConnectionPoolCreate(), respectively.

tagInfo (IN)

This parameter is used only for session pooling.

This indicates the type of session that the user wants. If you want a default session, you must set this to NULL. See the Comments for a detailed explanation of this parameter.

tagInfo_len (IN)

The length, in bytes, of tagInfo. Used for session pooling only.

retTagInfo (OUT)

This parameter is used only for session pooling. This indicates the type of session that is returned to the user. See the Comments for a detailed explanation of this parameter.

retTagInfo_len (OUT)

The length, in bytes, of retTagInfo. Used for session pooling only.

found (OUT)

This parameter is used only for session pooling. If the type of session that the user requested was returned (that is, the value of tagInfo and retTagInfo is the same), then found is set to TRUE. Otherwise, found is set to FALSE.

mode (IN)

The valid modes are:

  • OCI_DEFAULT

  • OCI_SESSGET_CPOOL

  • OCI_SESSGET_SPOOL

  • OCI_SESSGET_CREDPROXY

  • OCI_SESSGET_CREDEXT - Supported only for heterogeneous pools.

  • OCI_SESSGET_PURITY_NEW

  • OCI_SESSGET_PURITY_SELF

  • OCI_SESSGET_SPOOL_MATCHANY

  • OCI_SESSGET_STMTCACHE

  • OCI_SESSGET_SYSDBA

In the default (nonpooling) case, the following modes are valid:

OCI_SESSGET_STMTCACHE - Enables statement caching in the session.

OCI_SESSGET_CREDEXT - Returns a session authenticated with external credentials.

OCI_SESSGET_SYSDBA - Returns a session with SYSDBA privilege for either nonpooling or for session pooling.

For connection pooling, the following modes are valid:

OCI_SESSGET_CPOOL - Must be set to use connection pooling.

OCI_SESSGET_STMTCACHE - Enables statement caching in the session.

OCI_SESSGET_CREDPROXY - Returns a proxy session. The user is given a session that is authenticated by the user name provided in the OCISessionGet() call, through the proxy credentials supplied in the OCIConnectionPoolCreate() call.

OCI_SESSGET_CREDEXT - Returns a session authenticated with external credentials.

For session pooling, the following modes are valid:

OCI_SESSGET_SPOOL - Must be set to use session pooling.

OCI_SESSGET_SYSDBA - Returns a session with SYSDBA privilege for either nonpooling or for session pooling.

OCI_SESSGET_CREDEXT - Returns a session authenticated with external credentials.

OCI_SESSGET_CREDPROXY - In this case, the user is given a session that is authenticated by the user name provided in the OCISessionGet() call, through the proxy credentials supplied in the OCISessionPoolCreate() call.

OCI_SESSGET_SPOOL_MATCHANY - Refers to the tagging behavior. If this mode is set, then a session that has a different tag than what was asked for, may be returned. See the Comments section.

For database resident connection pooling, the following modes are valid:

OCI_SESSGET_PURITY_SELF - The application can use a session that has been used before. You can also specify application-specific tags.

OCI_SESSGET_PURITY_NEW - The application requires a new session that is not tainted with any prior session state. This is the default.

Comments

The tags provide a way for users to customize sessions in the pool. A client can get a default or untagged session from a pool, set certain attributes on the session (such as globalization settings), and return the session to the pool, labeling it with an appropriate tag in the OCISessionRelease() call.

The user, or some other user, can request a session with the same attributes, and can do so by providing the same tag in the OCISessionGet() call.

If a user asks for a session with tag 'A', and a matching session is not available, an appropriately authenticated untagged session (session with a NULL tag) is returned, if such a session is free. If even an untagged session is not free and OCI_SESSGET_SPOOL_MATCHANY has been specified, then an appropriately authenticated session with a different tag is returned. If OCI_SESSGET_SPOOL_MATCHANY is not set, then a session with a different tag is never returned.

Example 16-4 demonstrates the use of OCI_ATTR_MODULE with session pooling.

Example 16-4 Using the OCI_ATTR_MODULE Attribute with OCI Session Pooling

Oratext *module = (Oratext*) "mymodule";
/* Allocate the pool handle */
 checkerr(errhp,OCIHandleAlloc(envhp,(void**)&poolhp,
                             OCI_HTYPE_SPOOL,0,0));
 
 checkerr(errhp,OCISessionPoolCreate(envhp,
                             errhp,poolhp,&poolname,&pnamelen,
                             (oratext*)conn_str,
                             len,min,max,incr,0,0,0,0,OCI_DEFAULT));
 
 /* Allocate the auth handle for session get */
 checkerr(errhp, OCIHandleAlloc(envhp,
                 (void**)&authp, OCI_HTYPE_AUTHINFO, 0,0));
 
 checkerr(errhp,OCIAttrSet(authp, OCI_HTYPE_AUTHINFO,
                  username, strlen((char*)username), OCI_ATTR_USERNAME,errhp);
 checkerr(errhp,OCIAttrSet(authp, OCI_HTYPE_AUTHINFO,
                  password, strlen((char*)password), OCI_ATTR_PASSWORD,
                  errhp));
 
 checkerr(errhp,OCISessionGet(envhp,errhp,
              &svchp,authp,poolname, pnamelen,0,0,0,0,0,
              OCI_SESSGET_SPOOL));
 
/* Get the user handle from the service context handle */
checkerr(errhp, OCIAttrGet(svhcp, OCI_HTYPE_SVCCTX, &usrhp_svc,
               0,OCI_ATTR_SESSION,errhp));
 
/* Set module name on the user handle that you obtained */
checkerr (errhp, OCIAttrSet(usrhp_svc, OCI_HTYPE_SESSION, module, 
               strlen((char*)module), OCI_ATTR_MODULE,errhp));
/* Make Database calls. */

Restrictions on Attributes Supported for OCI Session Pools

You can use the following pre-session-creation attributes with OCI session pools:

OCI_ATTR_EDITION
OCI_ATTR_DRIVER_NAME
OCI_ATTR_USERNAME,
OCI_ATTR_PASSWORD,
OCI_ATTR_CONNECTION_CLASS,
OCI_ATTR_PURITY

However, OCI_ATTR_EDITION and OCI_ATTR_DRIVERNAME can only be specified during OCISessionPoolCreate() by setting them on the OCIAuthInfo handle that is an attribute of OCISPool handle. They cannot be specified on the OCIAuthInfo handle passed into individual OCISessionGet() calls. This ensures that all sessions that are part of an OCI session pool have uniform values for these attributes.

Example 16-5 shows how to use the OCI_ATTR_EDITION attribute with an OCI session pool.

Example 16-5 Using the OCI_ATTR_EDITION Attribute with OCI Session Pooling

/* allocate the auth handle to be set on the spool handle */
  checkerr(errhp, OCIHandleAlloc(envhp,(void**)&authp_sp,
                  OCI_HTYPE_AUTHINFO, 0,0));
                  
  /* Set the edition on the auth handle */
 
  checkerr(errhp,OCIAttrSet(authp_sp, OCI_HTYPE_AUTHINFO, 
                   "Patch_Bug_12345", strlen("Patch_Bug_12345"), 
                  OCI_ATTR_EDITION,errhp));
 
/* Allocate the pool handle */
 checkerr(errhp,OCIHandleAlloc(envhp,(void**)&poolhp,
                             OCI_HTYPE_SPOOL,0,0));
 
  /* Set the auth handle created above on the spool handle */
 checkerr(errhp,OCIAttrSet(poolhp, OCI_HTYPE_SPOOL,authp_sp,
                  0,OCI_ATTR_SPOOL_AUTH,errhp));
checkerr(errhp,OCISessionPoolCreate(envhp,
                             errhp,poolhp,&poolname,&pnamelen,
                             (oratext*)conn_str,
                             len,min,max,incr,0,0,0,0,OCI_DEFAULT));
 
  /* Allocate the auth handle for session get */
  checkerr(errhp, OCIHandleAlloc(envhp,
                 (void**)&authp_sessget, OCI_HTYPE_AUTHINFO, 0,0));
 
  checkerr(errhp,OCIAttrSet(authp_sessget, OCI_HTYPE_AUTHINFO,
                  username, strlen((char*)username), OCI_ATTR_USERNAME,errhp);
  checkerr(errhp,OCIAttrSet(authp_sessget, OCI_HTYPE_AUTHINFO,
                  password, strlen((char*)password), OCI_ATTR_PASSWORD,
                  errhp));
 
  checkerr(errhp,OCISessionGet(envhp,errhp,
              &svchp,authp_sessget,poolname, pnamelen,0,0,0,0,0,
              OCI_SESSGET_SPOOL));

You can use all post-session-creation attributes with OCI session pool. However, as a session pool can age out sessions, reuse preexisting sessions in the pool, or re-create new sessions transparently, Oracle recommends that the application explicitly set any post-session-creation attributes that it needs after getting a session from a pool. This ensures that the application logic works irrespective of the specific session returned by the OCI session pool.

OCISessionPoolCreate()

Purpose

Initializes a session pool for use with OCI session pooling and database resident connection pooling (DRCP). It starts sessMin number of sessions and connections to the database. Before making this call, make a call to OCIHandleAlloc() to allocate memory for the session pool handle.

Syntax

sword OCISessionPoolCreate ( OCIEnv           *envhp,
                             OCIError         *errhp, 
                             OCISPool         *spoolhp,
                             OraText          **poolName,
                             ub4              *poolNameLen,
                             const OraText    *connStr,
                             ub4              connStrLen,
                             ub4              sessMin, 
                             ub4              sessMax, 
                             ub4              sessIncr,
                             OraText          *userid,
                             ub4              useridLen,
                             OraText          *password,
                             ub4              passwordLen,
                             ub4              mode );

Parameters

envhp (IN)

A pointer to the environment handle in which the session pool is to be created.

errhp (IN/OUT)

An error handle that can be passed to OCIErrorGet().

spoolhp (IN/OUT)

A pointer to the session pool handle that is initialized.

poolName (OUT)

The name of the session pool returned. It is unique across all session pools in an environment. This value must be passed to the OCISessionGet() call.

poolNameLen (OUT)

Length of poolName in bytes.

connStr (IN)

The TNS alias of the database to connect to.

connStrLen (IN)

The length of connStr in bytes.

sessMin (IN)

Specifies the minimum number of sessions in the session pool.

This number of sessions are started by OCISessionPoolCreate(). After the sessions are started, sessions are opened only when necessary.

This value is used when mode is set to OCI_SPC_HOMOGENEOUS. Otherwise, it is ignored.

sessMax (IN)

Specifies the maximum number of sessions that can be opened in the session pool. After this value is reached, no more sessions are opened. The valid values are 1 and higher.

sessIncr (IN)

Allows applications to set the next increment for sessions to be started if the current number of sessions is less than sessMax. The valid values are 0 and higher.

sessMin + sessIncr cannot be more than sessMax.

userid (IN)

Specifies the userid with which to start the sessions.

useridLen (IN)

Length of the userid in bytes.

password (IN)

The password for the corresponding userid.

passwordLen (IN)

The length of the password in bytes.

mode (IN)

The modes supported are:

  • OCI_DEFAULT - For a new session pool creation.

  • OCI_SPC_REINITIALIZE - After creating a session pool, if you want to change the pool attributes dynamically (change the sessMin, sessMax, and sessIncr parameters), call OCISessionPoolCreate() with mode set to OCI_SPC_REINITIALIZE. When mode is set to OCI_SPC_REINITIALIZE, then connStr, userid, and password are ignored.

  • OCI_SPC_STMTCACHE - An OCI statement cache is created for the session pool. If the pool is not created with OCI statement caching turned on, server-side statement caching is automatically used. Note that in general, client-side statement caching gives better performance.

  • OCI_SPC_HOMOGENEOUS - All sessions in the pool are authenticated with the user name and password passed to OCISessionPoolCreate(). The authentication handle (parameter authInfop) passed into OCISessionGet() is ignored in this case. Moreover, the sessMin and the SessIncr values are considered only in this case. No proxy session can be created in this mode. This mode can be used in database resident connection pooling (DRCP).

  • OCI_SPC_NO_RLB - By default, the runtime connection load balancing is enabled in the session pool if the client and the server are capable of supporting it. To turn it off, use the new mode, OCI_SPC_NO_RLB mode of OCISessionPoolCreate(). You can only use this mode at the time of pool creation. If this mode is passed for a pool that has been created, an error, ORA-24411, is thrown.

Comments

Authentication Note

A session pool can contain two types of connections to the database: direct connections and proxy connections. To make a proxy connection, a user must have Connect through Proxy privilege.

See Also:

For more information about proxy connections, see

When the session pool is created, the userid and password may or may not be specified. If these values are NULL, no proxy connections can exist in this pool. If mode is set to OCI_SPC_HOMOGENEOUS, no proxy connection can exist.

A userid and password pair may also be specified through the authentication handle in the OCISessionGet() call. If this call is made with mode set to OCI_SESSGET_CREDPROXY, then the user is given a session that is authenticated by the userid provided in the OCISessionGet() call, through the proxy credentials supplied in the OCISessionPoolCreate() call. In this case, the password in the OCISessionGet() call is ignored.

If OCISessionGet() is called with mode not set to OCI_SESSGET_CREDPROXY, then the user gets a direct session that is authenticated by the credentials provided in the OCISessionGet() call. If none have been provided in this call, the user gets a session authenticated by the credentials in the OCISessionPoolCreate() call.

Example

Example 16-6 shows how to disable runtime load balancing.

Example 16-6 Disabling Runtime Load Balancing

OCISessionPoolCreate(envhp, errhp, spoolhp, (OraText **)&poolName, 
                     (ub4 *)&poolNameLen,
                     database, (ub4) strlen ((const signed char *) database),
                     sessMin, sessMax, sessIncr, (OraText *) appusername,
                     (ub4) strlen ((const signed char *) appusername),
                     (OraText *) apppassword,
                     (ub4) strlen ((const signed char *) apppassword),
                     OCI_SPC_HOMOGENEOUS | OCI_SPC_NO_RLB);

OCISessionPoolDestroy()

Purpose

Destroys a session pool.

Syntax

sword OCISessionPoolDestroy ( OCISPool     *spoolhp, 
                              OCIError     *errhp,
                              ub4          mode );
spoolhp (IN/OUT)

The session pool handle for the session pool to be destroyed.

errhp (IN/OUT)

An error handle that can be passed to OCIErrorGet().

mode (IN)

Currently, OCISessionPoolDestroy() supports modes OCI_DEFAULT and OCI_SPD_FORCE.

If this call is made with mode set to OCI_SPD_FORCE, and there are active sessions in the pool, the sessions are closed and the pool is destroyed. However, if this mode is not set, and there are busy sessions in the pool, an error is returned.

OCISessionRelease()

Purpose

Releases a session that was retrieved using OCISessionGet(). The exact behavior of this call is determined by the mode in which the corresponding OCISessionGet() function was called. In the default case, it closes the session or connection. For connection pooling, it closes the session and returns the connection to the pool. For session pooling, it returns the session or connection pair to the pool, and any pending transaction is committed.

Syntax

sword OCISessionRelease ( OCISvcCtx       *svchp,
                          OCIError        *errhp,
                          OraText         *tag,
                          ub4             tag_len,
                          ub4             mode );

Parameters

svchp (IN)

The service context that was populated during the corresponding OCISessionGet() call.

In the default case, the session and connection associated with this handle is closed.

In the connection pooling case, the session is closed and the connection released to the pool.

For session pooling, the session or connection pair associated with this service context is released to the pool.

errhp (IN/OUT)

The OCI error handle.

tag (IN)

This parameter is used only for session pooling.

This parameter is ignored unless mode OCI_SESSRLS_RETAG is specified. In this case, the session is labeled with this tag and returned to the pool. If this is NULL, then the session is not tagged.

tag_len (IN)

This parameter is used only for session pooling.

Length of the tag. This is ignored unless mode OCI_SESSRLS_RETAG is set.

mode (IN)

The supported modes are:

  • OCI_DEFAULT

  • OCI_SESSRLS_DROPSESS

  • OCI_SESSRLS_RETAG

You can only use OCI_DEFAULT for the default case and for connection pooling.

OCI_SESSRLS_DROPSESS and OCI_SESSRLS_RETAG are only used for session pooling.

When OCI_SESSRLS_DROPSESS is specified, the session is removed from the session pool.

The tag on the session is altered if and only if OCI_SESSRLS_RETAG is set. If this mode is not set, the tag and tag_len parameters are ignored.

Comments

Be careful to pass in the correct tag when using the tag parameter. If a default session is requested and the user sets certain properties on this session (probably through an ALTER SESSION command), then the user must label this session appropriately by tagging it as such.

If, however, the user requested a tagged session and got one, and has changed the properties on the session, then the user must pass in a different tag if appropriate.

For the correct working of the session pool layer, the application developer must be very careful to pass in the correct tag to the OCISessionGet() and OCISessionRelease() calls.

OCITerminate()

Purpose

Detaches the process from the shared memory subsystem and releases the shared memory.

Syntax

sword OCITerminate ( ub4    mode);

Parameters

mode (IN)

Call-specific mode. Valid value:

  • OCI_DEFAULT - Executes the default call.

Comments

OCITerminate() should be called only once for each process and is the counterpart of the OCIEnvCreate(), OCIEnvNlsCreate(), deprecated OCIInitialize() calls. The call tries to detach the process from the shared memory subsystem and shut it down. It also performs additional process cleanup operations. When two or more processes connecting to the same shared memory call OCITerminate() simultaneously, the fastest one releases the shared memory subsystem completely and the slower ones must terminate.