Added script demonstrating advanced queuing.

2016-02-25 18:23:41 -07:00 · 2016-02-25 18:23:41 -07:00 · d59bd1922b
commit d59bd1922b
parent fca5acc558
1 changed files with 117 additions and 0 deletions
--- a/samples/AdvancedQueuing.py
+++ b/samples/AdvancedQueuing.py
@ -0,0 +1,117 @@
+#------------------------------------------------------------------------------
+# AdvancedQueuing.py
+#   This script demonstrates how to use advanced queuing using cx_Oracle. It
+# creates a simple type and enqueues and dequeues a few objects.
+#------------------------------------------------------------------------------
+
+from __future__ import print_function
+
+CONNECT_STRING = "user/pw@tns"
+BOOK_TYPE_NAME = "UDT_BOOK"
+QUEUE_NAME = "BOOKS"
+QUEUE_TABLE_NAME = "BOOK_QUEUE"
+
+import cx_Oracle
+import decimal
+
+# connect to database
+connection = cx_Oracle.Connection(CONNECT_STRING)
+cursor = connection.cursor()
+
+# drop queue table, if present
+cursor.execute("""
+        select count(*)
+        from user_tables
+        where table_name = :name""", name = QUEUE_TABLE_NAME)
+count, = cursor.fetchone()
+if count > 0:
+    print("Dropping queue table...")
+    cursor.callproc("dbms_aqadm.drop_queue_table", (QUEUE_TABLE_NAME, True))
+
+# drop type, if present
+cursor.execute("""
+        select count(*)
+        from user_types
+        where type_name = :name""", name = BOOK_TYPE_NAME)
+count, = cursor.fetchone()
+if count > 0:
+    print("Dropping books type...")
+    cursor.execute("drop type %s" % BOOK_TYPE_NAME)
+
+# create type
+print("Creating books type...")
+cursor.execute("""
+        create type %s as object (
+            title varchar2(100),
+            authors varchar2(100),
+            price number(5,2)
+        );""" % BOOK_TYPE_NAME)
+
+# create queue table and quueue and start the queue
+print("Creating queue table...")
+cursor.callproc("dbms_aqadm.create_queue_table",
+        (QUEUE_TABLE_NAME, BOOK_TYPE_NAME))
+cursor.callproc("dbms_aqadm.create_queue", (QUEUE_NAME, QUEUE_TABLE_NAME))
+cursor.callproc("dbms_aqadm.start_queue", (QUEUE_NAME,))
+
+# enqueue a few messages
+booksType = connection.gettype(BOOK_TYPE_NAME)
+book1 = booksType.newobject()
+book1.TITLE = "The Fellowship of the Ring"
+book1.AUTHORS = "Tolkien, J.R.R."
+book1.PRICE = decimal.Decimal("10.99")
+book2 = booksType.newobject()
+book2.TITLE = "Harry Potter and the Philosopher's Stone"
+book2.AUTHORS = "Rowling, J.K."
+book2.PRICE = decimal.Decimal("7.99")
+for book in (book1, book2):
+    print("Enqueuing book", book.TITLE)
+    cursor.execute("""
+            declare
+                t_MessageId             raw(16);
+                t_Options               dbms_aq.enqueue_options_t;
+                t_MessageProperties     dbms_aq.message_properties_t;
+            begin
+                dbms_aq.enqueue(
+                        queue_name => :queueName,
+                        enqueue_options => t_Options,
+                        message_properties => t_MessageProperties,
+                        payload => :book,
+                        msgid => t_MessageId);
+            end;""",
+            queueName = QUEUE_NAME,
+            book = book)
+connection.commit()
+
+# dequeue the messages
+var = cursor.var(cx_Oracle.OBJECT, typename = BOOK_TYPE_NAME)
+while True:
+    cursor.execute("""
+            declare
+                t_MessageId             raw(16);
+                t_Options               dbms_aq.dequeue_options_t;
+                t_MessageProperties     dbms_aq.message_properties_t;
+                no_messages             exception;
+                pragma exception_init(no_messages, -25228);
+            begin
+                t_Options.navigation := dbms_aq.FIRST_MESSAGE;
+                t_Options.wait := dbms_aq.NO_WAIT;
+                begin
+                    dbms_aq.dequeue(
+                            queue_name => :queueName,
+                            dequeue_options => t_Options,
+                            message_properties => t_MessageProperties,
+                            payload => :book,
+                            msgid => t_MessageId);
+                exception
+                when no_messages then
+                    :book := null;
+                end;
+            end;""",
+            queueName = QUEUE_NAME,
+            book = var)
+    book = var.getvalue()
+    if book is None:
+        break
+    print("Dequeued book", book.TITLE)
+