The document discusses Oracle inter-session communication and describes how sessions can communicate with each other using pipes in the System Global Area (SGA). It provides code examples of a package that implements a logger using DBMS_PIPE to send log messages from one session to another session that reads from the pipe.

1. Oracle Inter-Session
Communication
Oren Nakdimon
www.db-oriented.com
 oren@db-oriented.com
 +972-54-4393763
@DBoriented

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Oren
Nakdimon
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Nakdimon
http://db-oriented.com
Who Am
I?

3. INTER-SESSION COMMUNICATION

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Session Session
Session

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Session Session
Session

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Session
SGA
Session
Session

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Session
SGA
Session
Session

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Session
Outbox
SGA
Inbox
Session
Session
Outbox
Inbox Outbox
Inbox

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Session
Outbox
SGA
Inbox
Session
Session
Outbox
Inbox Outbox
Inbox

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Session
Outbox
SGA
Inbox
Session
Session
Outbox
Inbox Outbox
Inbox

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Session
Outbox
SGA
Session
Outbox
Inbox
Session
Inbox Outbox
Inbox
Outbox

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Session
Outbox
SGA
Session
Outbox
Inbox
Session
Inbox Outbox
Inbox
Outbox Inbox

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Session
Session
Outbox
SGA
Session
Outbox
Inbox
Inbox Outbox
Outbox
Outbox Inbox

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Session
Session
Outbox
SGA
Session
Outbox
Inbox
Inbox Outbox
Outbox
Outbox Inbox

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Session
Session
Outbox
SGA
Session
Outbox
Inbox
Inbox Outbox
Outbox
Outbox Inbox

16. DEMO
Logger

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create or replace package pipe_demo as
procedure log(i_text in varchar2);
procedure get_next
(
o_user out varchar2,
o_sid out number,
o_host out varchar2,
o_time out date,
o_text out varchar2
);
end pipe_demo;

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create or replace package pipe_demo as
procedure log(i_text in varchar2);
procedure get_next
(
o_user out varchar2,
o_sid out number,
o_host out varchar2,
o_time out date,
o_text out varchar2
);
end pipe_demo;

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create or replace package pipe_demo as
procedure log(i_text in varchar2);
procedure get_next
(
o_user out varchar2,
o_sid out number,
o_host out varchar2,
o_time out date,
o_text out varchar2
);
end pipe_demo;

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create or replace package body pipe_demo as
c_log_pipe constant varchar2(13) := 'DEMO_LOG_PIPE';
procedure log(i_text in varchar2) is
l_status number;
begin
dbms_pipe.pack_message(user);
dbms_pipe.pack_message(to_number(sys_context('userenv', 'sid')));
dbms_pipe.pack_message(sys_context('userenv', 'host'));
dbms_pipe.pack_message(sysdate);
dbms_pipe.pack_message(i_text);
l_status := dbms_pipe.send_message(c_log_pipe);
if l_status != 0 then
raise_application_error(-20000,
'dbms_pipe.send_message failed with status ' || l_status);
end if;
end log;

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create or replace package body pipe_demo as
c_log_pipe constant varchar2(13) := 'DEMO_LOG_PIPE';
procedure log(i_text in varchar2) is
l_status number;
begin
dbms_pipe.pack_message(user);
dbms_pipe.pack_message(to_number(sys_context('userenv', 'sid')));
dbms_pipe.pack_message(sys_context('userenv', 'host'));
dbms_pipe.pack_message(sysdate);
dbms_pipe.pack_message(i_text);
l_status := dbms_pipe.send_message(c_log_pipe);
if l_status != 0 then
raise_application_error(-20000,
'dbms_pipe.send_message failed with status ' || l_status);
end if;
end log;

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create or replace package body pipe_demo as
c_log_pipe constant varchar2(13) := 'DEMO_LOG_PIPE';
procedure log(i_text in varchar2) is
l_status number;
begin
dbms_pipe.pack_message(user);
dbms_pipe.pack_message(to_number(sys_context('userenv', 'sid')));
dbms_pipe.pack_message(sys_context('userenv', 'host'));
dbms_pipe.pack_message(sysdate);
dbms_pipe.pack_message(i_text);
l_status := dbms_pipe.send_message(c_log_pipe);
if l_status != 0 then
raise_application_error(-20000,
'dbms_pipe.send_message failed with status ' || l_status);
end if;
end log;

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create or replace package body pipe_demo as
c_log_pipe constant varchar2(13) := 'DEMO_LOG_PIPE';
procedure log(i_text in varchar2) is
l_status number;
begin
dbms_pipe.pack_message(user);
dbms_pipe.pack_message(to_number(sys_context('userenv', 'sid')));
dbms_pipe.pack_message(sys_context('userenv', 'host'));
dbms_pipe.pack_message(sysdate);
dbms_pipe.pack_message(i_text);
l_status := dbms_pipe.send_message(c_log_pipe);
if l_status != 0 then
raise_application_error(-20000,
'dbms_pipe.send_message failed with status ' || l_status);
end if;
end log;
pack_message (number)
pack_message (varchar2)
pack_message (date)
pack_message_raw
pack_message_rowid

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create or replace package body pipe_demo as
c_log_pipe constant varchar2(13) := 'DEMO_LOG_PIPE';
procedure log(i_text in varchar2) is
l_status number;
begin
dbms_pipe.pack_message(user);
dbms_pipe.pack_message(to_number(sys_context('userenv', 'sid')));
dbms_pipe.pack_message(sys_context('userenv', 'host'));
dbms_pipe.pack_message(sysdate);
dbms_pipe.pack_message(i_text);
l_status := dbms_pipe.send_message(c_log_pipe);
if l_status != 0 then
raise_application_error(-20000,
'dbms_pipe.send_message failed with status ' || l_status);
end if;
end log;

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procedure get_next
(
o_user out varchar2,
o_sid out number,
o_host out varchar2,
o_time out date,
o_text out varchar2
) is
l_status number;
begin
l_status := dbms_pipe.receive_message(pipename => c_log_pipe);
if l_status != 0 then
raise_application_error(-20000,
'dbms_pipe.receive_message failed with status ' || l_status);
end if;
dbms_pipe.unpack_message(o_user);
dbms_pipe.unpack_message(o_sid);
dbms_pipe.unpack_message(o_host);
dbms_pipe.unpack_message(o_time);
dbms_pipe.unpack_message(o_text);
end get_next;
end pipe_demo;

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procedure get_next
(
o_user out varchar2,
o_sid out number,
o_host out varchar2,
o_time out date,
o_text out varchar2
) is
l_status number;
begin
l_status := dbms_pipe.receive_message(pipename => c_log_pipe);
if l_status != 0 then
raise_application_error(-20000,
'dbms_pipe.receive_message failed with status ' || l_status);
end if;
dbms_pipe.unpack_message(o_user);
dbms_pipe.unpack_message(o_sid);
dbms_pipe.unpack_message(o_host);
dbms_pipe.unpack_message(o_time);
dbms_pipe.unpack_message(o_text);
end get_next;
end pipe_demo;

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procedure get_next
(
o_user out varchar2,
o_sid out number,
o_host out varchar2,
o_time out date,
o_text out varchar2
) is
l_status number;
begin
l_status := dbms_pipe.receive_message(pipename => c_log_pipe);
if l_status != 0 then
raise_application_error(-20000,
'dbms_pipe.receive_message failed with status ' || l_status);
end if;
dbms_pipe.unpack_message(o_user);
dbms_pipe.unpack_message(o_sid);
dbms_pipe.unpack_message(o_host);
dbms_pipe.unpack_message(o_time);
dbms_pipe.unpack_message(o_text);
end get_next;
end pipe_demo;
unpack_message (number)
unpack_message (varchar2)
unpack_message (date)
unpack_message_raw
unpack_message_rowid

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public class Logger {
public static void main(String args[]) throws SQLException {
Properties info = new Properties();
info.put(OracleConnection.CONNECTION_PROPERTY_USER_NAME, DB_USER);
info.put(OracleConnection.CONNECTION_PROPERTY_PASSWORD, DB_PASSWORD);
OracleDataSource ods = new OracleDataSource();
ods.setURL(DB_URL);
ods.setConnectionProperties(info);
try (OracleConnection connection = (OracleConnection) ods.getConnection()) {
DatabaseMetaData dbmd = connection.getMetaData();
System.out.println("Ready...");
System.out.println();
System.out.println("Time Host User SID Message");
System.out.println("--------------- -------------- ----- --- -------");
processRequests(connection);
System.out.println("Bye!");
System.out.println();
}
}

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public class Logger {
public static void main(String args[]) throws SQLException {
Properties info = new Properties();
info.put(OracleConnection.CONNECTION_PROPERTY_USER_NAME, DB_USER);
info.put(OracleConnection.CONNECTION_PROPERTY_PASSWORD, DB_PASSWORD);
OracleDataSource ods = new OracleDataSource();
ods.setURL(DB_URL);
ods.setConnectionProperties(info);
try (OracleConnection connection = (OracleConnection) ods.getConnection()) {
DatabaseMetaData dbmd = connection.getMetaData();
System.out.println("Ready...");
System.out.println();
System.out.println("Time Host User SID Message");
System.out.println("--------------- -------------- ----- --- -------");
processRequests(connection);
System.out.println("Bye!");
System.out.println();
}
}

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public class Logger {
public static void main(String args[]) throws SQLException {
Properties info = new Properties();
info.put(OracleConnection.CONNECTION_PROPERTY_USER_NAME, DB_USER);
info.put(OracleConnection.CONNECTION_PROPERTY_PASSWORD, DB_PASSWORD);
OracleDataSource ods = new OracleDataSource();
ods.setURL(DB_URL);
ods.setConnectionProperties(info);
try (OracleConnection connection = (OracleConnection) ods.getConnection()) {
DatabaseMetaData dbmd = connection.getMetaData();
System.out.println("Ready...");
System.out.println();
System.out.println("Time Host User SID Message");
System.out.println("--------------- -------------- ----- --- -------");
processRequests(connection);
System.out.println("Bye!");
System.out.println();
}
}

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public class Logger {
public static void main(String args[]) throws SQLException {
Properties info = new Properties();
info.put(OracleConnection.CONNECTION_PROPERTY_USER_NAME, DB_USER);
info.put(OracleConnection.CONNECTION_PROPERTY_PASSWORD, DB_PASSWORD);
OracleDataSource ods = new OracleDataSource();
ods.setURL(DB_URL);
ods.setConnectionProperties(info);
try (OracleConnection connection = (OracleConnection) ods.getConnection()) {
DatabaseMetaData dbmd = connection.getMetaData();
System.out.println("Ready...");
System.out.println();
System.out.println("Time Host User SID Message");
System.out.println("--------------- -------------- ----- --- -------");
processRequests(connection);
System.out.println("Bye!");
System.out.println();
}
}

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public static void processRequests(Connection connection) throws SQLException {
String user;
int sid;
String host;
Timestamp time;
String text = " ";
CallableStatement callableStatement =
connection.prepareCall("{ call PIPE_DEMO.GET_NEXT(?,?,?,?,?) }");
callableStatement.registerOutParameter(1, java.sql.Types.VARCHAR);
callableStatement.registerOutParameter(2, java.sql.Types.INTEGER);
callableStatement.registerOutParameter(3, java.sql.Types.VARCHAR);
callableStatement.registerOutParameter(4, java.sql.Types.DATE);
callableStatement.registerOutParameter(5, java.sql.Types.VARCHAR);
do {
callableStatement.executeUpdate();
user = callableStatement.getString(1);
sid = callableStatement.getInt(2);
host = callableStatement.getString(3);
time = callableStatement.getTimestamp(4);
text = callableStatement.getString(5);
System.out.println(time + " " + host + " " + user + " " + String.format("%3s",

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public static void processRequests(Connection connection) throws SQLException {
String user;
int sid;
String host;
Timestamp time;
String text = " ";
CallableStatement callableStatement =
connection.prepareCall("{ call PIPE_DEMO.GET_NEXT(?,?,?,?,?) }");
callableStatement.registerOutParameter(1, java.sql.Types.VARCHAR);
callableStatement.registerOutParameter(2, java.sql.Types.INTEGER);
callableStatement.registerOutParameter(3, java.sql.Types.VARCHAR);
callableStatement.registerOutParameter(4, java.sql.Types.DATE);
callableStatement.registerOutParameter(5, java.sql.Types.VARCHAR);
do {
callableStatement.executeUpdate();
user = callableStatement.getString(1);
sid = callableStatement.getInt(2);
host = callableStatement.getString(3);
time = callableStatement.getTimestamp(4);
text = callableStatement.getString(5);
System.out.println(time + " " + host + " " + user + " " + String.format("%3s",

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public static void processRequests(Connection connection) throws SQLException {
String user;
int sid;
String host;
Timestamp time;
String text = " ";
CallableStatement callableStatement =
connection.prepareCall("{ call PIPE_DEMO.GET_NEXT(?,?,?,?,?) }");
callableStatement.registerOutParameter(1, java.sql.Types.VARCHAR);
callableStatement.registerOutParameter(2, java.sql.Types.INTEGER);
callableStatement.registerOutParameter(3, java.sql.Types.VARCHAR);
callableStatement.registerOutParameter(4, java.sql.Types.DATE);
callableStatement.registerOutParameter(5, java.sql.Types.VARCHAR);
do {
callableStatement.executeUpdate();
user = callableStatement.getString(1);
sid = callableStatement.getInt(2);
host = callableStatement.getString(3);
time = callableStatement.getTimestamp(4);
text = callableStatement.getString(5);
System.out.println(time + " " + host + " " + user + " " + String.format("%3s",

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CallableStatement callableStatement =
connection.prepareCall("{ call PIPE_DEMO.GET_NEXT(?,?,?,?,?) }");
callableStatement.registerOutParameter(1, java.sql.Types.VARCHAR);
callableStatement.registerOutParameter(2, java.sql.Types.INTEGER);
callableStatement.registerOutParameter(3, java.sql.Types.VARCHAR);
callableStatement.registerOutParameter(4, java.sql.Types.DATE);
callableStatement.registerOutParameter(5, java.sql.Types.VARCHAR);
do {
callableStatement.executeUpdate();
user = callableStatement.getString(1);
sid = callableStatement.getInt(2);
host = callableStatement.getString(3);
time = callableStatement.getTimestamp(4);
text = callableStatement.getString(5);
System.out.println(time + " " + host + " " + user + " " + String.format("%3s",
sid) + " " + text);
} while (!text.equals("ABORT"));
callableStatement.close();
}
}

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CallableStatement callableStatement =
connection.prepareCall("{ call PIPE_DEMO.GET_NEXT(?,?,?,?,?) }");
callableStatement.registerOutParameter(1, java.sql.Types.VARCHAR);
callableStatement.registerOutParameter(2, java.sql.Types.INTEGER);
callableStatement.registerOutParameter(3, java.sql.Types.VARCHAR);
callableStatement.registerOutParameter(4, java.sql.Types.DATE);
callableStatement.registerOutParameter(5, java.sql.Types.VARCHAR);
do {
callableStatement.executeUpdate();
user = callableStatement.getString(1);
sid = callableStatement.getInt(2);
host = callableStatement.getString(3);
time = callableStatement.getTimestamp(4);
text = callableStatement.getString(5);
System.out.println(time + " " + host + " " + user + " " + String.format("%3s",
sid) + " " + text);
} while (!text.equals("ABORT"));
callableStatement.close();
}
}

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CallableStatement callableStatement =
connection.prepareCall("{ call PIPE_DEMO.GET_NEXT(?,?,?,?,?) }");
callableStatement.registerOutParameter(1, java.sql.Types.VARCHAR);
callableStatement.registerOutParameter(2, java.sql.Types.INTEGER);
callableStatement.registerOutParameter(3, java.sql.Types.VARCHAR);
callableStatement.registerOutParameter(4, java.sql.Types.DATE);
callableStatement.registerOutParameter(5, java.sql.Types.VARCHAR);
do {
callableStatement.executeUpdate();
user = callableStatement.getString(1);
sid = callableStatement.getInt(2);
host = callableStatement.getString(3);
time = callableStatement.getTimestamp(4);
text = callableStatement.getString(5);
System.out.println(time + " " + host + " " + user + " " + String.format("%3s",
sid) + " " + text);
} while (!text.equals("ABORT"));
callableStatement.close();
}
}

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CallableStatement callableStatement =
connection.prepareCall("{ call PIPE_DEMO.GET_NEXT(?,?,?,?,?) }");
callableStatement.registerOutParameter(1, java.sql.Types.VARCHAR);
callableStatement.registerOutParameter(2, java.sql.Types.INTEGER);
callableStatement.registerOutParameter(3, java.sql.Types.VARCHAR);
callableStatement.registerOutParameter(4, java.sql.Types.DATE);
callableStatement.registerOutParameter(5, java.sql.Types.VARCHAR);
do {
callableStatement.executeUpdate();
user = callableStatement.getString(1);
sid = callableStatement.getInt(2);
host = callableStatement.getString(3);
time = callableStatement.getTimestamp(4);
text = callableStatement.getString(5);
System.out.println(time + " " + host + " " + user + " " + String.format("%3s",
sid) + " " + text);
} while (!text.equals("ABORT"));
callableStatement.close();
}
}

39. PIPES
A Single Consumer

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SGA
Session
Inbox Outbox
Session
Inbox Outbox
Session
Inbox Outbox
Session
Inbox Outbox
Session
Inbox Outbox
Session
Inbox Outbox
Session
Inbox Outbox
Session
Inbox Outbox

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SGA
Session
Inbox Outbox
Session
Inbox Outbox
Session
Inbox Outbox
Session
Inbox Outbox
Session
Inbox Outbox
Session
Inbox Outbox
Session
Inbox Outbox
Session
Inbox Outbox

42. This presentation is available in http://db-oriented.com/presentations
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SGA
Session
Inbox Outbox
Session
Inbox Outbox
Session
Inbox Outbox
Session
Inbox Outbox
Session
Inbox Outbox
Session
Inbox Outbox
Session
Inbox Outbox
Session
Inbox Outbox

43. PIPES
Multiple Consumers

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SGA
Session
Inbox Outbox
Session
Inbox Outbox
Session
Inbox Outbox
Session
Inbox Outbox
Session
Inbox Outbox
Session
Inbox Outbox

45. DEMO
Multiple Consumers

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create or replace package pipe_demo as
procedure log(i_text in varchar2);
procedure get_next
(
o_user out varchar2,
o_sid out number,
o_host out varchar2,
o_time out date,
o_text out varchar2
);
procedure send_many_logs
(
i_text in varchar2,
i_how_many in binary_integer
);
end pipe_demo;

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create or replace package body pipe_demo as
...
procedure send_many_logs
(
i_text in varchar2,
i_how_many in binary_integer
) is
c_alert_name constant varchar2(10) := 'DEMO_ALERT';
l_message varchar2(100);
l_status number;
begin
dbms_alert.register(c_alert_name);
dbms_alert.waitone(c_alert_name, l_message, l_status);
for i in 1 .. i_how_many
loop
pipe_demo.log(i_text || '# ' || to_char(i));
end loop;
dbms_alert.remove(c_alert_name);
end send_many_logs;
end pipe_demo;

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create or replace package body pipe_demo as
...
procedure send_many_logs
(
i_text in varchar2,
i_how_many in binary_integer
) is
c_alert_name constant varchar2(10) := 'DEMO_ALERT';
l_message varchar2(100);
l_status number;
begin
dbms_alert.register(c_alert_name);
dbms_alert.waitone(c_alert_name, l_message, l_status);
for i in 1 .. i_how_many
loop
pipe_demo.log(i_text || '# ' || to_char(i));
end loop;
dbms_alert.remove(c_alert_name);
end send_many_logs;
end pipe_demo;

50. ALERTS (SIGNALS)

51. This presentation is available in http://db-oriented.com/presentations
©
Oren
Nakdimon
©
Oren
Nakdimon
Session
Session
Session
Session
Session
Session

52. This presentation is available in http://db-oriented.com/presentations
©
Oren
Nakdimon
©
Oren
Nakdimon
create or replace package body pipe_demo as
...
procedure send_many_logs
(
i_text in varchar2,
i_how_many in binary_integer
) is
c_alert_name constant varchar2(10) := 'DEMO_ALERT';
l_message varchar2(100);
l_status number;
begin
dbms_alert.register(c_alert_name);
dbms_alert.waitone(c_alert_name, l_message, l_status);
for i in 1 .. i_how_many
loop
pipe_demo.log(i_text || '# ' || to_char(i));
end loop;
dbms_alert.remove(c_alert_name);
end send_many_logs;
end pipe_demo;

53. This presentation is available in http://db-oriented.com/presentations
©
Oren
Nakdimon
©
Oren
Nakdimon
create or replace package body pipe_demo as
...
procedure send_many_logs
(
i_text in varchar2,
i_how_many in binary_integer
) is
c_alert_name constant varchar2(10) := 'DEMO_ALERT';
l_message varchar2(100);
l_status number;
begin
dbms_alert.register(c_alert_name);
dbms_alert.waitone(c_alert_name, l_message, l_status);
for i in 1 .. i_how_many
loop
pipe_demo.log(i_text || '# ' || to_char(i));
end loop;
dbms_alert.remove(c_alert_name);
end send_many_logs;
end pipe_demo;

54. This presentation is available in http://db-oriented.com/presentations
©
Oren
Nakdimon
©
Oren
Nakdimon
create or replace package body pipe_demo as
...
procedure send_many_logs
(
i_text in varchar2,
i_how_many in binary_integer
) is
c_alert_name constant varchar2(10) := 'DEMO_ALERT';
l_message varchar2(100);
l_status number;
begin
dbms_alert.register(c_alert_name);
dbms_alert.waitone(c_alert_name, l_message, l_status);
for i in 1 .. i_how_many
loop
pipe_demo.log(i_text || '# ' || to_char(i));
end loop;
dbms_alert.remove(c_alert_name);
end send_many_logs;
end pipe_demo;
There is also dbms_alert.waitany

55. This presentation is available in http://db-oriented.com/presentations
©
Oren
Nakdimon
©
Oren
Nakdimon
create or replace package body pipe_demo as
...
procedure send_many_logs
(
i_text in varchar2,
i_how_many in binary_integer
) is
c_alert_name constant varchar2(10) := 'DEMO_ALERT';
l_message varchar2(100);
l_status number;
begin
dbms_alert.register(c_alert_name);
dbms_alert.waitone(c_alert_name, l_message, l_status);
for i in 1 .. i_how_many
loop
pipe_demo.log(i_text || '# ' || to_char(i));
end loop;
dbms_alert.remove(c_alert_name);
end send_many_logs;
end pipe_demo; There is also dbms_alert.removeall

56. PIPES
Request and Response

57. This presentation is available in http://db-oriented.com/presentations
©
Oren
Nakdimon
©
Oren
Nakdimon
SGA
Session
Inbox Outbox
Session
Inbox Outbox
Session
Inbox Outbox

58. This presentation is available in http://db-oriented.com/presentations
©
Oren
Nakdimon
©
Oren
Nakdimon
SGA
Session
Inbox Outbox
Session
Inbox Outbox
Session
Inbox Outbox
dbms_pipe.unique_session_name

59. This presentation is available in http://db-oriented.com/presentations
©
Oren
Nakdimon
©
Oren
Nakdimon
DBMS_PIPE DBMS_ALERT
Type Named Pipes / Queue Signals / Broadcast
Implementation SGA structure Table
Transactional? Non-Transactional Transactional
Consumers of a specific
message
Single Consumer Zero-to-Multiple Consumers
Blocked Publisher? When pipe is full (“pipe put”
wait event)
When other session signaled
to the same alert and hasn’t
committed yet (TX lock), but
only if there are registered
consumers
Possible Loss of Messages? Instance crash/shutdown Multiple signals to the same
alert before read by the
consumer

60. THANK YOU
Oren Nakdimon
www.db-oriented.com
 oren@db-oriented.com
 +972-54-4393763
@DBoriented