Initial Import: Database transaction handling.

Initial Import: Error handling using ewf error library.
Added a CMS_ERROR_FILTER as part of registered filters of CMS_SERVICE

cms/cms.ecf

@@ -10,6 +10,8 @@
 		<library name="http" location="$ISE_LIBRARY\contrib\library\network\protocol\http\http-safe.ecf"/>
 		<library name="json" location="$ISE_LIBRARY\contrib\library\text\parser\json\library\json-safe.ecf" readonly="false"/>
 		<library name="layout" location="..\layout\layout.ecf"/>
+		
+		<library name="error" location="$ISE_LIBRARY\contrib\library\utility\general\error\error-safe.ecf"/>
 		<library name="http_authorization" location="$ISE_LIBRARY\contrib\library\network\authentication\http_authorization\http_authorization-safe.ecf" readonly="false"/>
 		<library name="persistence_mysql" location="..\persistence\implementation\mysql\persistence_mysql.ecf" readonly="false"/>
 		<library name="smarty" location="$ISE_LIBRARY\contrib\library\text\template\smarty\smarty-safe.ecf" readonly="false"/>

cms/src/configuration/cms_default_setup.e

@@ -17,6 +17,7 @@ feature {NONE} -- Initialization
 
 	make (a_layout: CMS_LAYOUT)
 		do
+			create error_handler.make
 			layout := a_layout
 			create configuration.make (layout)
 			initialize
@@ -28,7 +29,6 @@ feature {NONE} -- Initialization
 			create modules.make (3)
 			build_api_service
 			build_mailer
-
 			initialize_modules
 		end
 
@@ -61,7 +61,6 @@ feature {NONE} -- Initialization
 --			m.enable
 --			modules.extend (m)
 
-
 			create {NODE_MODULE} m.make (Current)
 			m.enable
 			modules.extend (m)
@@ -89,7 +88,10 @@ feature -- Access
 	build_api_service
 		local
 			l_database: DATABASE_CONNECTION
+			l_retry: BOOLEAN
+			l_message: STRING
 		do
+			if not l_retry then
 				to_implement ("Refactor database setup")
 				if attached (create {JSON_CONFIGURATION}).new_database_configuration (layout.application_config_path) as l_database_config then
 					create {DATABASE_CONNECTION_MYSQL} l_database.login_with_connection_string (l_database_config.connection_string)
@@ -98,6 +100,32 @@ feature -- Access
 					create {DATABASE_CONNECTION_NULL} l_database.make_common
 					create api_service.make (create {CMS_STORAGE_NULL})
 				end
+			else
+				to_implement ("Workaround code, persistence layer does not implement yet this kind of error handling.")
+					-- error hanling.
+				create {DATABASE_CONNECTION_NULL} l_database.make_common
+				create api_service.make (create {CMS_STORAGE_NULL})
+				create l_message.make (1024)
+				if attached ((create {EXCEPTION_MANAGER}).last_exception) as l_exception then
+					if attached l_exception.description as l_description then
+						l_message.append (l_description.as_string_32)
+						l_message.append ("%N%N")
+					elseif attached l_exception.trace as l_trace then
+						l_message.append (l_trace)
+						l_message.append ("%N%N")
+					else
+						l_message.append (l_exception.out)
+						l_message.append ("%N%N")
+					end
+				else
+					l_message.append ("The application crash without available information")
+					l_message.append ("%N%N")
+				end
+				error_handler.add_custom_error (0, " Database Connection ", l_message)
+			end
+		rescue
+			l_retry := True
+			retry
 		end
 
 	build_auth_engine

cms/src/configuration/cms_setup.e

@@ -32,6 +32,12 @@ feature -- Access
 		deferred
 		end
 
+
+feature -- Status Report
+
+	error_handler: ERROR_HANDLER
+		-- Error handler.			
+
 feature -- Access: Site
 
 	site_id: READABLE_STRING_8

cms/src/service/cms_service.e

@@ -165,9 +165,15 @@ feature -- Filters
 		do
 			log.write_debug (generator + ".create_filter")
 			l_filter := Void
+
 				-- Maintenance
 			create {WSF_MAINTENANCE_FILTER} f
 			f.set_next (l_filter)
+			l_filter := f
+
+			 	-- Error Filter
+			create {CMS_ERROR_FILTER} f.make (setup)
+			f.set_next (l_filter)
 			l_filter := f
 
 				-- Include filters from modules

cms/src/service/filter/cms_error_filter.e

@@ -0,0 +1,33 @@
+note
+	description: "Summary description for {CMS_ERROR_FILTER}."
+	date: "$Date$"
+	revision: "$Revision$"
+
+class
+	CMS_ERROR_FILTER
+
+inherit
+
+	WSF_URI_TEMPLATE_HANDLER
+	CMS_HANDLER
+	WSF_FILTER
+
+create
+	make
+
+feature -- Basic operations
+
+	execute (req: WSF_REQUEST; res: WSF_RESPONSE)
+			-- Execute the filter
+		do
+			if not setup.error_handler.has_error then
+				log.write_information (generator + ".execute")
+				execute_next (req, res)
+			else
+				log.write_critical (generator + ".execute" + setup.error_handler.as_string_representation )
+				(create {ERROR_500_CMS_RESPONSE}.make (req, res, setup, "master2/error")).execute
+				setup.error_handler.reset
+			end
+		end
+
+end

persistence/implementation/common/database/database_connection.e

@@ -10,7 +10,7 @@ inherit
 
 	DATABASE_CONFIG
 
-	SHARED_ERROR
+	SHARED_ERROR_HANDLER
 
 feature {NONE} -- Initialization
 
@@ -72,6 +72,65 @@ feature -- Database Setup
 	keep_connection: BOOLEAN
 			-- Keep connection alive?
 
+feature -- Transactions
+
+	begin_transaction
+			-- Start a transaction which will be terminated by a call to `rollback' or `commit'.
+		local
+			rescued: BOOLEAN
+		do
+			if not rescued then
+				if db_control.is_ok then
+					db_control.begin
+				else
+					database_error_handler.add_database_error (db_control.error_message_32, db_control.error_code)
+				end
+			end
+		rescue
+			rescued := True
+			exception_as_error ((create {EXCEPTION_MANAGER}).last_exception)
+			db_control.reset
+			retry
+		end
+
+	commit
+			-- Commit updates in the database.
+		local
+			rescued: BOOLEAN
+		do
+			if not rescued then
+				if db_control.is_ok then
+					db_control.commit
+				else
+					database_error_handler.add_database_error (db_control.error_message_32, db_control.error_code)
+				end
+			end
+		rescue
+			rescued := True
+			exception_as_error ((create {EXCEPTION_MANAGER}).last_exception)
+			db_control.reset
+			retry
+		end
+
+	rollback
+			-- Rollback updates in the database.
+		local
+			rescued: BOOLEAN
+		do
+			if not rescued then
+				if db_control.is_ok then
+					db_control.rollback
+				else
+					database_error_handler.add_database_error (db_control.error_message_32, db_control.error_code)
+				end
+			end
+		rescue
+			rescued := True
+			exception_as_error ((create {EXCEPTION_MANAGER}).last_exception)
+			db_control.reset
+			retry
+		end
+
 feature -- Change Element
 
 	not_keep_connection

persistence/implementation/common/database/database_handler.e

@@ -8,7 +8,7 @@ deferred class
 
 inherit
 
-	SHARED_ERROR
+	SHARED_ERROR_HANDLER
 
 feature -- Access
 
@@ -42,15 +42,15 @@ feature -- Modifiers
 
 feature -- Functionality Store Procedures
 
-	execute_reader
+	execute_store_reader
-			-- Execute store.
+			-- Execute a `store' to read data.
 		require
 			store_not_void: store /= void
 		deferred
 		end
 
-	execute_writer
+	execute_store_writer
-			-- Execute store.
+			-- Execute a `store' to write data.
 		require
 			store_not_void: store /= void
 		deferred
@@ -59,7 +59,7 @@ feature -- Functionality Store Procedures
 feature -- SQL Queries
 
 	execute_query
-			-- Execute query.
+			-- Execute sql query, the read data from the database.
 		require
 			query_not_void: query /= void
 		deferred
@@ -147,14 +147,49 @@ feature -- Access
 
 feature -- Status Report
 
-	has_error: BOOLEAN
-			-- Is there an error?
-
 	count: INTEGER
 			-- Number of rows, last execution.
 		deferred
 		end
 
+	connection: DATABASE_CONNECTION
+		-- Database connection.
+
+	db_control: DB_CONTROL
+		-- Database control.
+		do
+			Result := connection.db_control
+		end
+
+	db_result: detachable DB_RESULT
+		-- Database query result.
+
+	db_selection: detachable DB_SELECTION
+		-- Database selection.
+
+	db_change: detachable DB_CHANGE
+		-- Database modification.	
+
+feature -- Error handling
+
+	check_database_change_error
+			-- Check database error from `db_change'.
+		do
+			if attached db_change as l_change and then not l_change.is_ok then
+				database_error_handler.add_database_error (l_change.error_message_32, l_change.error_code)
+				log.write_error (generator + ".check_database_change_error: " + l_change.error_message_32)
+			end
+		end
+
+	check_database_selection_error
+			-- Check database error from `db_selection'.
+		do
+			if attached db_selection as l_selection and then not l_selection.is_ok then
+				database_error_handler.add_database_error (l_selection.error_message_32, l_selection.error_code)
+				log.write_error (generator + ".check_database_selection_error: " + l_selection.error_message_32)
+			end
+		end
+
 feature {NODE_DATA_PROVIDER}-- Implementation
 
 	connect

persistence/implementation/common/database/database_handler_impl.e

@@ -21,7 +21,6 @@ feature {NONE} -- Initialization
 		do
 			connection := a_connection
 			create last_query.make_now
-			set_successful
 		ensure
 			connection_not_void: connection /= Void
 			last_query_not_void: last_query /= Void
@@ -29,71 +28,52 @@ feature {NONE} -- Initialization
 
 feature -- Functionality
 
-	execute_reader
+	execute_store_reader
 			-- Execute stored procedure that returns data.
 		local
 			l_db_selection: DB_SELECTION
 			l_retried: BOOLEAN
 		do
 			if not l_retried then
-				if not keep_connection then
-					connect
-				end
-
 				if attached store as l_store then
 					create l_db_selection.make
 					db_selection := l_db_selection
 					items := l_store.execute_reader (l_db_selection)
+					check_database_selection_error
 				end
-
-				if not keep_connection then
-					disconnect
-				end
-				set_successful
 				log.write_debug ( generator+".execute_reader Successful")
 			end
 		rescue
-			set_last_error_from_exception ("Store procedure execution")
-			log.write_critical (generator+ ".execute_reader " + last_error_message)
-			if is_connected then
-				disconnect
-			end
 			l_retried := True
+			exception_as_error ((create {EXCEPTION_MANAGER}).last_exception)
+			if attached db_selection as l_selection then
+				l_selection.reset
+			end
 			retry
 		end
 
-	execute_writer
+	execute_store_writer
 			-- Execute stored procedure that update/add data.
 		local
 			l_db_change: DB_CHANGE
 			l_retried : BOOLEAN
 		do
 		    if not  l_retried then
-				if not keep_connection and not is_connected then
-					connect
-				end
 
 				if attached store as l_store then
 					create l_db_change.make
-					db_update := l_db_change
+					db_change := l_db_change
 					l_store.execute_writer (l_db_change)
-					if not l_store.has_error then
+					check_database_change_error
-						db_control.commit
 				end
-				end
-				if not keep_connection then
-					disconnect
-				end
-				set_successful
 				log.write_debug ( generator+".execute_writer Successful")
 			end
 		rescue
-			set_last_error_from_exception ("Store procedure execution")
-			log.write_critical (generator+ ".execute_writer " + last_error_message)
-			if is_connected then
-				disconnect
-			end
 			l_retried := True
+			exception_as_error ((create {EXCEPTION_MANAGER}).last_exception)
+			if attached db_change as l_change then
+				l_change.reset
+			end
 			retry
 		end
 
@@ -106,60 +86,43 @@ feature -- SQL Queries
 			l_retried: BOOLEAN
 		do
 			if not l_retried then
-				if not keep_connection then
-					connect
-				end
-
 				if attached query as l_query then
 					create l_db_selection.make
 					db_selection := l_db_selection
 					items := l_query.execute_reader (l_db_selection)
+					check_database_selection_error
 				end
-				if not keep_connection then
-					disconnect
-				end
-				set_successful
 			end
 		rescue
-			set_last_error_from_exception ("execute_query")
-			log.write_critical (generator+ ".execute_query " + last_error_message)
-			if is_connected then
-				disconnect
-			end
 			l_retried := True
+			exception_as_error ((create {EXCEPTION_MANAGER}).last_exception)
+			if attached db_selection as l_selection then
+				l_selection.reset
+			end
 			retry
 		end
 
 
 	execute_change
-			-- Execute sqlquery that update/add data.
+			-- Execute sql_query that update/add data.
 		local
 			l_db_change: DB_CHANGE
 			l_retried : BOOLEAN
 		do
 		    if not  l_retried then
-				if not keep_connection and not is_connected then
-					connect
-				end
-
 				if attached query as l_query then
 					create l_db_change.make
-					db_update := l_db_change
+					db_change := l_db_change
 					l_query.execute_change (l_db_change)
-					db_control.commit
+					check_database_change_error
 				end
-				if not keep_connection then
-					disconnect
-				end
-				set_successful
 			end
 		rescue
-			set_last_error_from_exception ("Store procedure execution")
-			log.write_critical (generator+ ".execute_writer " + last_error_message)
-			if is_connected then
-				disconnect
-			end
 			l_retried := True
+			exception_as_error ((create {EXCEPTION_MANAGER}).last_exception)
+			if attached db_change as l_change then
+				l_change.reset
+			end
 			retry
 		end
 
@@ -207,24 +170,6 @@ feature -- Iteration
 
 feature {NONE} -- Implementation
 
-	connection: DATABASE_CONNECTION
-		-- Database connection.
-
-	db_control: DB_CONTROL
-		-- Database control.
-		do
-			Result := connection.db_control
-		end
-
-	db_result: detachable DB_RESULT
-		-- Database query result.
-
-	db_selection: detachable DB_SELECTION
-		-- Database selection.
-
-	db_update: detachable DB_CHANGE
-		-- Database modification.	
-
 	last_query: DATE_TIME
 		-- Last time when a query was executed.
 
@@ -263,7 +208,7 @@ feature {NONE} -- Implementation
 	affected_row_count: INTEGER
 			--  The number of rows changed, deleted, or inserted by the last statement.
 		do
-			if attached db_update as l_update then
+			if attached db_change as l_update then
 				Result := l_update.affected_row_count
 			end
 		end

persistence/implementation/common/database/database_iteration_cursor.e

@@ -1,5 +1,5 @@
 note
-	description: "External iteration cursor for {ESA_DATABASE_HANDLER}"
+	description: "External iteration cursor for {DATABASE_HANDLER}"
 	date: "$Date: 2014-08-20 15:21:15 -0300 (mi., 20 ago. 2014) $"
 	revision: "$Revision: 95678 $"
 

persistence/implementation/common/database/database_no_change_error.e

@@ -0,0 +1,27 @@
+note
+	description: "Summary description for {DATABASE_NO_CHANGE_ERROR}."
+	author: ""
+	date: "$Date$"
+	revision: "$Revision$"
+
+class
+	DATABASE_NO_CHANGE_ERROR
+
+inherit
+	DATABASE_ERROR
+		redefine
+			make_from_message
+		end
+
+create
+	make_from_message
+
+feature {NONE} -- Init
+
+	make_from_message (a_m: like message; a_code: like code)
+			-- Create from `a_m'
+		do
+			make (a_code, once "Database No Change Error", a_m)
+		end
+
+end

persistence/implementation/common/database/database_query.e

@@ -8,14 +8,14 @@ class
 
 inherit
 
-	SHARED_ERROR
+	SHARED_ERROR_HANDLER
 
 	REFACTORING_HELPER
 
 create
 	data_reader
 
-feature -- Intialization
+feature {NONE} -- Intialization
 
 	data_reader (a_query: STRING; a_parameters: STRING_TABLE [detachable ANY])
 			-- SQL data reader for the query `a_query' with arguments `a_parameters'
@@ -29,6 +29,8 @@ feature -- Intialization
 			parameters_set: parameters = a_parameters
 		end
 
+feature -- Execution		
+
 	execute_reader (a_base_selection: DB_SELECTION): detachable LIST [DB_RESULT]
 			-- Execute the Current sql query.
 		do
@@ -42,7 +44,6 @@ feature -- Intialization
 				a_base_selection.load_result
 				Result := a_base_selection.container
 			else
-				set_last_error (a_base_selection.error_message_32, generator + ".execute_reader"  )
 				log.write_error (generator + "." + a_base_selection.error_message_32)
 			end
 			unset_map_name (a_base_selection)
@@ -50,17 +51,12 @@ feature -- Intialization
 		end
 
 	execute_change (a_base_change: DB_CHANGE)
-			-- Execute the Current sql query .
+			-- Execute the Current sql query to change/update data in the database.
 		do
 			to_implement ("Check test dynamic sequel. to redesign.")
 			set_map_name (a_base_change)
 			a_base_change.set_query (query)
 			a_base_change.execute_query
-			if a_base_change.is_ok then
-			else
-				set_last_error (a_base_change.error_message_32, generator + ".execute_reader"  )
-				log.write_error (generator + "." + a_base_change.error_message_32)
-			end
 			unset_map_name (a_base_change)
 		end
 
@@ -72,17 +68,6 @@ feature --  Access
 	parameters: STRING_TABLE [detachable ANY]
 			-- query parameters.
 
-feature -- Status Report
-
-	has_error: BOOLEAN
-		-- is there an error?
-
-	error_message: detachable STRING_32
-		-- Error message if any.
-
-	error_code: INTEGER
-		-- Error code.
-
 feature {NONE} -- Implementation
 
 	set_map_name (a_base_selection: DB_EXPRESSION)
@@ -140,4 +125,4 @@ feature {NONE} -- Implementation
 		end
 
 
-end -- ESA_DATABASE_QUERY
+end -- DATABASE_QUERY

persistence/implementation/common/database/error/database_error.e

@@ -0,0 +1,23 @@
+note
+	description: "Error from database"
+	date: "$Date: 2013-08-08 16:39:49 -0300 (ju. 08 de ago. de 2013) $"
+	revision: "$Revision: 195 $"
+
+class
+	DATABASE_ERROR
+
+inherit
+	ERROR_CUSTOM
+
+create
+	make_from_message
+
+feature {NONE} -- Init
+
+	make_from_message (a_m: like message; a_code: like code)
+			-- Create from `a_m'
+		do
+			make (a_code, once "Database Error", a_m)
+		end
+
+end

persistence/implementation/common/database/error/database_error_handler.e

@@ -15,21 +15,21 @@ create
 feature -- Error operation
 
 	add_database_error (a_message: READABLE_STRING_32; a_code: INTEGER)
-			-- Add a database error
+			-- Add a database error.
 		local
---			l_error: DATABASE_ERROR
+			l_error: DATABASE_ERROR
 		do
---			create l_error.make_from_message (a_message, a_code)
+			create l_error.make_from_message (a_message, a_code)
---			add_error (l_error)
+			add_error (l_error)
 		end
 
 	add_database_no_change_error (a_message: READABLE_STRING_32; a_code: INTEGER)
-			-- Add a database error
+			-- Add a database error.
 		local
---			l_error: DATABASE_NO_CHANGE_ERROR
+			l_error: DATABASE_NO_CHANGE_ERROR
 		do
---			create l_error.make_from_message (a_message, a_code)
+			create l_error.make_from_message (a_message, a_code)
---			add_error (l_error)
+			add_error (l_error)
 		end
 
 end

persistence/implementation/common/database/error/shared_error_handler.e

@@ -6,14 +6,26 @@ note
 class
 	SHARED_ERROR_HANDLER
 
+inherit
+
+	SHARED_LOGGER
+
 feature -- Access
 
 	database_error_handler: DATABASE_ERROR_HANDLER
-			-- Error handler
+			-- Error handler.
 		once
 			create Result.make
 		end
 
+feature -- Status Report
+
+	has_error: BOOLEAN
+			-- Has error?
+		do
+			Result := database_error_handler.has_error
+		end
+
 feature -- Helper
 
 	exception_as_error (a_e: like {EXCEPTION_MANAGER}.last_exception)

persistence/implementation/mysql/src/cms_storage_mysql.e

@@ -21,6 +21,7 @@ feature {NONE} -- Initialization
 		require
 			is_connected: a_connection.is_connected
 		do
+			connection := a_connection
 			log.write_information (generator+".make_with_database is database connected?  "+ a_connection.is_connected.out )
 			create node_provider.make (a_connection)
 			create user_provider.make (a_connection)
@@ -125,11 +126,14 @@ feature -- Change: user
 	save_user (a_user: CMS_USER)
 			-- Add a new user `a_user'.
 		do
+
 			if
 				attached a_user.password as l_password and then
 				attached a_user.email as l_email
 			then
+				connection.begin_transaction
 				user_provider.new_user (a_user.name, l_password, l_email)
+				connection.commit
 			else
 				set_last_error ("User or Password not attached", generator + ".save_user")
 			end
@@ -282,4 +286,6 @@ feature {NONE} -- Post process
 	user_provider: USER_DATA_PROVIDER
 			-- User Data provider.
 
+	connection: DATABASE_CONNECTION
+			-- Current database connection.
 end

persistence/implementation/mysql/src/database/database_connection_mysql.e

@@ -34,17 +34,11 @@ feature -- Initialization
 				if keep_connection then
 					connect
 				end
-				set_successful
 			else
 				create db_control.make
 			end
 		rescue
-			create db_control.make
+			exception_as_error ((create {EXCEPTION_MANAGER}).last_exception)
-			set_last_error_from_exception ("Connection execution")
-			log.write_critical (generator + ".make_common:" + last_error_message)
-			if is_connected then
-				disconnect
-			end
 			l_retried := True
 			retry
 		end
@@ -66,17 +60,11 @@ feature -- Initialization
 				if keep_connection then
 					connect
 				end
-				set_successful
 			else
 				create db_control.make
 			end
 		rescue
-			create db_control.make
+			exception_as_error ((create {EXCEPTION_MANAGER}).last_exception)
-			set_last_error_from_exception ("Connection execution")
-			log.write_critical (generator + ".make_common:" + last_error_message)
-			if is_connected then
-				disconnect
-			end
 			l_retried := True
 			retry
 		end

persistence/implementation/mysql/src/provider/node_data_provider.e

@@ -34,7 +34,6 @@ feature -- Status Report
 	is_successful: BOOLEAN
 			-- Is the last execution sucessful?
 		do
-			Result := db_handler.successful
 		end
 
 feature -- Access
@@ -481,13 +480,6 @@ feature {NONE} -- Implementation
 	post_execution
 			-- Post database execution.
 		do
-			if db_handler.successful then
-				set_successful
-			else
-				if attached db_handler.last_error then
-					set_last_error_from_handler (db_handler.last_error)
-				end
-			end
 		end
 
 end

persistence/implementation/mysql/src/provider/role_data_provider.e

@@ -35,7 +35,7 @@ feature -- Status Report
 	is_successful: BOOLEAN
 			-- Is the last execution sucessful?
 		do
-			Result := db_handler.successful
+--			Result := db_handler.successful
 		end
 
 	has_roles: BOOLEAN
@@ -210,13 +210,7 @@ feature {NONE} -- Implementation
 	post_execution
 			-- Post database execution.
 		do
-			if db_handler.successful then
+
-				set_successful
-			else
-				if attached db_handler.last_error then
-					set_last_error_from_handler (db_handler.last_error)
-				end
-			end
 		end
 
 end

persistence/implementation/mysql/src/provider/user_data_provider.e

@@ -34,7 +34,6 @@ feature -- Status Report
 	is_successful: BOOLEAN
 			-- Is the last execution sucessful?
 		do
-			Result := db_handler.successful
 		end
 
 	has_user: BOOLEAN
@@ -311,13 +310,6 @@ feature {NONE} -- Implementation
 	post_execution
 			-- Post database execution.
 		do
-			if db_handler.successful then
-				set_successful
-			else
-				if attached db_handler.last_error then
-					set_last_error_from_handler (db_handler.last_error)
-				end
-			end
 		end
 
 end

persistence/implementation/mysql/tests/util/clean_db.e

@@ -24,6 +24,7 @@ feature
 		do
 			create l_parameters.make (0)
 
+			a_connection.begin_transaction
 
 				-- Clean Profiles
 			db_handler(a_connection).set_query (create {DATABASE_QUERY}.data_reader (Sql_delete_user_profiles, l_parameters))
@@ -72,6 +73,7 @@ feature
 			db_handler(a_connection).set_query (create {DATABASE_QUERY}.data_reader (Rest_profiles_autoincrement, l_parameters))
 			db_handler(a_connection).execute_change
 
+			a_connection.commit
 		end