Oracle Service Bus Interview Questions with Answers

Oracle Service Bus Interview Questions with Answers

1. To connect to source system which service we will use?

Ans: We will use Proxy service to connect to Source system.

2. To connect to target system which service we will use?

Ans: We will use Business service to connect to target system.

3. What is Business Service?

Ans: It is a service in OSB which is used to connect to target system.

4. What is Message Flow?

Ans: Message flow is there in proxy service, we do all types of transformation, routing and other processing message flow only.

5. Do we have global variable in OSB (Can we access variable which is defined in proxy service message flow from other proxy service message flow)?

Ans: No, we can't access variable in proxy service message flow from other proxy service message flow.

6. Can we use direct bindings to call SOA composites?

Ans: Yes, we can direct binding-bindings to call SOA composites along with SOAP bindings.

7. Where the file will go if there is any error while polling the file?

Ans: During configuring file or ftp protocol in OSB, we need to specify error directory, so you can see file to that directory if file polling failed.

8. Why we use Split-Joins in OSB?

Ans: In short - For parallel processing. (Split-Joins let you send message invocations in parallel (in addition to sequentially) and to aggregate the responses.)

Oracle Service Bus's Split-Join feature lets you split a service payload, such as an order, into individual messages for concurrent processing. Concurrent processing, as opposed to sequential processing, greatly improves service performance. Split-Join achieves this task by splitting an input message payload into sub messages (split), routing them concurrently to their destinations, and aggregating the responses into one overall return message (join). This process of payload splitting and response aggregation is called a Split-Join pattern.

9. Types of Split-Joins?

Ans: Static and dynamic.

• Static Spilt-Join: The static Split-Join branches from the main execution thread of an OSB message flow by splitting a payload into a fixed number of new branches according to the configuration of the Split-Join. At design time you determine the number and variety of services to be invoked.
• Dynamic Spilt-Join: The dynamic Split-Join branches from the main execution thread of an OSB message flow by dynamically creating new branches according to the contents of the incoming payload. The dynamic Split-Join uses conditional logic to determine the number of branches to create. All requests are handled simultaneously, and the responses are aggregated into a single reply.

10. How to call Java code from OSB?

Ans: By using Java callout activity.

11. Can we use more than one route node in message flow?

Ans: No, we can't we use more than one route node in proxy service message flow.

12. When we call asynchronous service from OSB then how to get response back from that asynchronous service to OSB?

Ans: Design the proxy service which in turn calls business service which in turn calls asynchronous service. In the message flow of this proxy change the message header to below.

You need to specify ReplyTo value so that asynchronous service response came to CallSyncCompositeProxy proxy service. 

Remember ReplyTo address refers to CallSyncCompositeProxy endpoints.

1. What is throttling in OSB?

Ans: Throttling means we want to process certain messages in one time, then we need to set some parameters in OSB to do the required task.

2. To transform from binary to XML or XML to binary format what we will use in OSB?

Ans: We use Message Format Language (MFL).

A Message Format Language (MFL) document is a specialized XML document used to describe the layout of binary data. It is an Oracle proprietary language used to define rules to transform formatted binary data into XML data. An MFL document conforms to the mfl.dtd, which includes elements and attributes used to describe each field of data, as well as groupings of fields (groups), repetition, and aggregation.

When you create a business services or proxy services of Messaging Service type, you can select MFL types as the request message type or the response message type of the service

3. Can we use MDS in OSB?

Ans: No, Oracle Service Bus does not support MDS.

4. Can we use DVM’s in Oracle Service Bus?

Ans: No, we can’t use DVM’s in Oracle Service Bus.

5. How Security works in OSB?

Ans: Oracle Service Bus leverages Weblogic Security Framework.

6. Can we use OWSM to secure OSB services?

Ans: Yes, we can use OWSM to secure OSB services.

7. To secure OSB proxy service, which OWSM policy you will use?

Ans: To secure OSB proxy service, we use OWSM service side policy.

8. Can we invoke secure web service from OSB?

Ans: Yes, we can use OWSM client policy and invoke secure web service from OSB.

9. When we use service Account?

Ans: We use Service Account when we are invoking a service which required static authentication.

10. Can we re-use Service Account for other Business Services as well?

Ans: Yes, we can re-use the Service Account.

11. What is Transport-Level Security?

Ans: It refers to transport protocol security means secure the connection over which messages are transferred. E.g. HTTPS means HTTP over SSL.

12. What is Message-Level security?

Ans: Message level security is used when we want to protect the message exchanged between two applications.

13. What is Service pooling in OSB?

Ans: In OSB we can group together more than one service so that whenever one service goes down, request will route to next available service and end user can continue his work without any interruption.

14. How file pooling works in OSB?

Ans: There are below two ways to poll a file in OSB.

• OSB file protocol: We can use file protocol available in proxy service to poll the file.
• File adapter: we can create file adapter in Jdeveloper and import JCA, WSDL & XSD file of that adapter into OSB and generate proxy service from that.

15. Types of pipeline available in OSB?

Ans: We have two pipelines in OSB, Request and Response pipeline.

16. Can we invoke Restful service from OSB?

Ans: Yes, we can invoke Restful service from OSB.

17. We don’t have any DB protocol in OSB then how to read/write data from database using OSB?

Ans: We can use database adapter to read/write data from database. We can create database adapter in Jdeveloper, import adapter JCA,WSDL & XSD files to OSB and generate proxy or business service as per our requirement.

18. How to perform file listing in OSB?

Ans: To perform file listing in OSB, you need to create file adapter with file listing operation in Jdeveloper and use that only.

1. What is Service Result caching in OSB?

Ans: Service Result Caching is one of the options that you can use when you want to improve Oracle Service Bus performance. Service Result caching is used when we have business service which connects to external service which returns somewhat static response. So by using Service Result Caching we don’t hit external service for same request instead it will take the response from cache which improve the OSB performance

2. How to perform Service Callout in OSB?

Ans: We use Service Callout option inside Oracle Service Bus to call any service inside message flow to get the required data.

3. When we invoke proxy 2 from proxy 1 then which protocol we need use?

Ans: When there is internal proxy call in OSB then we use "local" transport instead of HTTP.

4. What is content based routing in OSB?

Ans: When we route the request message to different business services based on request message content, that is called content based routing.

5. What are different options available in OSB to read flat file?

Ans: We can read flat file in two different ways.

• Using Message Format Language (MFL): we can MFL in OSB to read flat files.
• File Adapter: Create file adapter which read flat file in Jdeveloper, copy JCA, WSDL & XSD file of file adapter in OSB and create proxy service which will read that flat file.

6. What is SLA alert in OSB?

Ans: A service-level agreement (SLA) is a contract between a service provider and a service consumer. In OSB monitoring framework we have SLA alerts which come into picture when there is violation of service level agreements.

7. How to move large file without reading it in OSB?

Ans: In Oracle SOA Suite we use "Move" opeartion to move large files from one location to another. But in Oracle Service Bus we don’t have that option available. But we can use Content Streaming option available for file protocol in OSB to move large files.

8. By how many ways we can do OSB development?

Ans: We can do development in OSB by two ways. Either we can use Eclipse which is IDE tool for OSB or we can use SB console for the development.

9. Will you prefer Eclipse or SB console for OSB development?

Ans: It is simple to work with SB console as compared to eclipse, so during initial phase we can opt for SB console and later go for eclipse. When we work at enterprise level, Eclipse is always recommended.

10. Do we need to create a session when we develop projects in Eclipse?

Ans: No, we need not to create a session when we develop projects in Eclipse, session will only come into picture when we deploy the project to server from eclipse.

11. Can multiple users work on SB console at one time?

Ans: Yes, multiple users with different user roles can work on SB console at same time as session will be created for each users individually.

12. Can we test the proxy service from Eclipse?

Ans: Yes, we can test the proxy service from Eclipse, for that we need to right click on the proxy service and then click on Run As and run it on server.

13.Can we create Xquery transformation in design mode in SB Console?

Ans: No, we have to write Xquery in source mode. We can create Xquery transformation in Eclipse.

14. Do we have the option to test the Xquery Transformation?

Ans: Yes, we can test the Xquery transformation.

15. Can we use XSLT file in OSB?

Ans: Yes, OSB support both Xquery and XSLT.

Oracle Service Bus

This chapter provides a brief introduction to Oracle Service Bus (OSB) and includes key getting started information such as starting the OSB Administration Console, customizing table views in the OSB Administration Console, and naming OSB resources.

Oracle Service Bus is a configuration-based, policy-driven enterprise service bus. It provides highly scalable and reliable service-oriented integration, service management, and traditional message brokering across heterogeneous IT environments. It combines intelligent message brokering with routing and transformation of messages, along with service monitoring and administration in a unified software product. Oracle Service Bus Administration Console enables you to control the service and policy configurations, and monitor system and operations tasks. Oracle Service Bus relies on Oracle WebLogic Server run-time facilities. For more information, see Oracle Fusion Middleware Concepts and Architecture for Oracle Service Bus.

Starting the Oracle Service Bus Administration Console

1. Start the Oracle Service Bus Admin server, as described in Section 35, "Starting Oracle Service Bus Servers."
2. When the server starts, enter the following URL in your browser:

   http://hostname:port/sbconsole
   

   where host represents the name of the machine on which WebLogic Server is running and port represents the port number.
   For example, if WebLogic Server is running on your local machine using the default port configuration, enter the following URL in your browser:
   http://localhost:7001/sbconsole
   The Oracle Service Bus Administration Console login page is displayed.
3. Enter the user name and the password you specified during the installation process.
   Note:

   The username and password for the Oracle Service Bus Examples domain is weblogic / welcome1.
4. Click Login.
   To log out, click Logout on the banner near the top of the right panel of the Oracle Service Bus Administration Console.

2.2 Customizing Table Views

Use the table customizer to display table information according on your specified settings.

Note that the default sort order for any table is determined by the first column in the table.

1. Click the Table Customizer icon. Additional fields are displayed.
   You can click Cancel at any time to close this table and retain the original settings.
2. In the Columns field, select the columns you want to display:
   1. Select a column name from the Available Columns field.
   2. Click the arrow to move this column name to the Selected Columns field.
      An asterisk denotes a required column.
   3. Repeat until you have listed all the column names you want to display in the Selected Columns field.
      In the Selected Columns field, you can use the Up and Down arrows to reorder the column names as required.
3. To remove columns from being displayed, move the column names from the Selected Columns field to the Available Columns field.
4. From the Rows list, select the number of rows you want to display on a single page.
5. Do one of the following:
   • To save these settings and close the table customizer, click Apply.
   • To discard your changes and retain the original settings, click Reset.

2.3 Resource Naming Restrictions

When naming any directory or resource in an Oracle Service Bus configuration, the following characters are allowed:

• All Java identifier characters, including Java keywords, as described in the "Identifiers" and "Keywords" sections of the Java Language Specification at http://java.sun.com/docs/books/jls/third_edition/html/lexical.html#3.8
• Blanks, periods, and hyphens within the names (not leading or trailing)

Characters such as / \ * : " < > ? | are not allowed.

Change Center

This chapter provides instructions on using the Change Center in the Oracle Service Bus Administration Console. Procedures include activating sessions, viewing configuration changes, undoing configuration tasks, and resolving conflicts.

The Change Center allows for team collaboration when services and metadata are being configured in Oracle Service Bus. Each user works in a sandbox session until the user is ready to check in the working configuration to the core configuration of the bus. The change center provides multiple levels of undo, and visibility into conflicts, as multiple users work on the configuration.

Most of the Change Center pages display different information based on whether you are in a session (for example, if you have clicked Edit in the Change Center) or outside a session. For example, in a session, the View Configuration Changes page that appears when you click View Changesin the Change Center lists all the changes you have made in that session; outside a session, the page lists all session activations.

Table 3-1 displays Change Center tasks and related session information.

Table 3-1 Change Center Tasks and Session Information

Tasks	Session Information
View conflicts	Inside session only: This link displays the number of conflicts occurring in a session. View and resolve all conflicts between changes in the current session and those made by all other sessions within the Oracle Service Bus Administration Console. A conflict occurs if a resource modified in the current session has already been modified and activated by another session. Two changes to the same resource by two sessions do not cause a conflict until one of the sessions is activated. This page also displays semantic errors for resources in the session.
View changes	Inside session: View the configuration changes you have made during the current session. Outside session: View configuration changes that are caused by previous session activations.
Undo changes	Inside session: Undo a change you have made during the current session. Outside session: Undo an activation of a session.
View all sessions	Inside and outside session: View all existing sessions within the Oracle Service Bus Administration Console.
Activate sessions	Inside session only: Activate the session.
View task details	Inside session: View details of a specific change you made in the current session. Outside session: View details of specific changes made by a previous session activation.

3.1 Using the Change Center

The Change Center module is the starting point for using the Oracle Service Bus Administration Console to make changes to your configuration. To make configuration changes using the Administration Console, you must use the Change Center to start a session.

1. Click Edit or Create to begin a session. The name of the session is displayed under Change Center.
2. Make the appropriate changes on the relevant page of the Administration Console.
3. Click Save on each page where you make a change. All the changes you have made in the current session are saved.
   Click Discard under Change Center, at any time during the session, to discard the changes you have made so far in the current session.
4. When you have finished making changes, click Activate under Change Center. Continue in Section 3.2, "Activating Sessions."

3.2 Activating Sessions

To activate a session:

1. Click Activate in the Change Center. The Activate Session page shows the session name, user name, and a description field.
   Creating a session and discarding a session proceed regardless of other activity in the system. However, if another session is in the process of being activated, the Activate Session page displays an error indicating the user that has the pending WebLogic Server changes. For information on resolving conflicts between changes made in your session and other activated sessions, see Section 3.9, "Viewing and Resolving Conflicts."
2. If there are validation errors, an error message is displayed, indicating that your session has validation errors. View and fix configuration conflicts before you proceed. For information on fixing conflicts, see Section 3.9, "Viewing and Resolving Conflicts."
   You will not be able to activate the session until you have viewed all conflicts. If new conflicts arise while you view the existing conflicts, before you activate, a message pops up informing you of the new conflicts.
3. Enter a description in the Description field. This description is displayed in the Description column when you click View Changes underChange Center to display configuration changes caused by session activations.
4. To activate the session, click Submit. If no new conflicts have arisen in the interim, the session ends and the configuration is deployed to the run time.
   Note:

   When you attempt to activate a session with a JMS endpoint URI on another server (a single server other than the one on which you are working, or a Managed Server in a cluster), ensure that the destination server is available.

   Oracle Service Bus does not allow registration of proxy services with JMS transport if the JMS endpoint URL specifies a destination that is unreachable. In other words, for JMS services, Oracle Service Bus checks if the specified connection factory exists; if it does not, a session activation error occurs.

3.3 Exiting Sessions

Click Exit under Change Center at any time to exit the session. However, the session does not end.

You can click Edit under Change Center to return to the session and continue making changes. This behavior also applies if you click Logout to log out of the Administration Console or close your browser. The session and all changes that you have made in the session persist even if you log out of the Administration Console or the server is restarted.

The session ends only after it has been activated. See Section 3.2, "Activating Sessions."

3.4 Viewing Configuration Changes

This page displays different information based on whether you are in a session (that is, you have clicked Edit in the Change Center) or outside a session.

• When you are in a session, the View Configuration Changes page displays a list of configuration changes that you have made during the current session. See "Viewing Configuration Changes in a Session" in this section.
• When you are outside a session, the View Configuration Changes page displays a list of configuration changes that were caused by previous session activations. See "Viewing Configuration Changes Caused by Session Activations" in this section.

Viewing Configuration Changes in a Session

1. If you have not already done so, click Create to create a new session for making changes to the current configuration. See Section 3.1, "Using the Change Center."
2. Make at least one change to the configuration.
3. Click View Changes under Change Center. For each change you have made to the configuration during the current session, the View Configuration Changes page displays the information shown in Table 3-2.

Table 3-2 In-Session Configuration Changes

Property	Description
Task	A description of the task that was implemented. The task is a link to the Task Details page. See Section 3.7, "Viewing Task Details."
Execution Time	The date and time that the task was executed.
User	The name of the user who implemented the change.
Task Status	The status of the task: Completed—the task was completed. Undone—the task was undone. Undo Completed—the undo was completed.
Undone By	The name of the user who undid the task. This field will contain None if the task has not been undone.
Options	Click the Undo icon to reverse the execution of the task. When you are working in a session, you can undo tasks in any order. As a result of undoing a task, the object of the task reverts to the state it was in before the task in question was performed. Note, however, that any tasks that were performed on the same object after the task that you undo are also undone. See Section 3.6, "Undoing Tasks."

Viewing Configuration Changes Caused by Session Activations

1. Make sure you are not in a session. See Section 3.3, "Exiting Sessions."
2. Click View Changes under Change Center. For each session you have previously activated, the View Configuration Changes page displays the information shown in Table 3-3.

Table 3-3 Activated Configuration Changes

Property	Description
Task	A description of the session that was activated. The task is a link to the Task Details page, which displays the operations that were performed in the session. See Section 3.7, "Viewing Task Details."
Description	An additional description of the session that was activated, if a description was entered when the session was activated using theActivate Session page.
Execution Time	The date and time that the session was activated.
User	The name of the user who activated the session.
Task Status	The status of the session: Activated—the session was activated. Partially Activated—displayed during session activation if one or more servers in a cluster are inaccessible, thus preventing activation of the session on those servers. When the servers become accessible, any unactivated changes will then be activated on them. Undone—the previously activated session was undone and all the operations performed in the session were discarded. Undo Activated—the undo was activated. In Progress—displayed if a session activation is in progress, as session activations can take a long time. Failed—displayed if a session activation fails. Oracle Service Bus tracks session activation failures but not failures due to individual updates inside a session.
Undone By	The name of the user who undid this task. This field will contain None if the session activation has not been undone.
Options	Click the Undo icon to reverse the session activation and the operations performed in that session. You can undo session activations in any order. Click the Undo into Session icon to create a new session pre-populated with the tasks needed to undo the changes activated in the session. See Section 3.6.2, "Undoing Into a Session."

3.5 Purging Session Activation History

You can purge sessions activated over a specific period, delimited by start and end dates. This action can only be performed outside a session.

Caution:

Purging session activation history involves deleting data that enables multiple levels of undo. In other words, if you purge session activation history for a specific period, you will not be able to undo sessions activated during that period.

1. Ensure that you are not in an active session, and click View Changes.
2. On the View Configuration Changes page, click Purge By Date. The Purge Session Activation History by Date page is displayed.
3. Enter the Start and End dates, in their respective fields, in the format: MM/DD/YYYY.
   The session activation history for all sessions between the dates specified will be deleted from Oracle Service Bus.

3.6 Undoing Tasks

Use the View Configuration Changes page to undo tasks that you have performed in your Oracle Service Bus configuration during your current session, and to undo session activations outside a session. Oracle Service Bus lets you undo multiple levels of session activation, constrained only by your system resources. For more information, see Section 3.6.1, "Order of Undoing Tasks."

Note:

If you upgrade from Oracle Service Bus version 2.1 to version 2.5, you will not be able to undo sessions activated before the upgrade. Sessions activated after the upgrade will be available in the session activation history, for undo.

Undoing a Task in a Session

1. Make sure you are in a session.
2. Click View Changes under Change Center.
3. In the Options column for a specific task, click the Undo icon.
   The task is undone.
   You can undo any change in the current session. However after that, if you change your mind, you can undo the undo, or if you again change your mind, you can undo the undo that undid a previous undo, and so on.

Undoing a Session That Was Activated Earlier

1. Make sure you are outside a session.
2. Click View Changes under Change Center.
3. Do one of the following:
   • In the Options column for a specific task, click the Undo icon. The session activation is undone.
   • In the Options column for a specific task, select the Undo into Session icon. A new session is created pre-populated with the tasks needed to undo the changes activated in the session. For more information, see Section 3.6.2, "Undoing Into a Session."

3.6.1 Order of Undoing Tasks

You can undo tasks in any order (provided that individual undo actions result in valid data). The undo operation sets the value of a resource to the value it had before the change to that resource.

In the case that the task that is being undone was one that created an object, there is no previous state to which an object can be returned—in other words, no object existed before this task was performed. Effectively, the undo operation deletes the new object from the session. In this case, errors occur for the objects that reference the one being deleted. You can view such errors on the View Conflicts page in the Change Center.

When you are not working in a session, you can access the View Configuration Changes page to see the sessions that were previously activated. You can undo these sessions. The system does not allow you to undo a session that was previously activated if an error in the run time configuration would result from the undo action. For example, if you attempt to undo a session activation that results in the removal of an object that is being referenced by another object, that undo action is disallowed.

It is possible to undo an undo action. In the Options column of the Undo of [task], click the Undo icon. Oracle Service Bus supports unlimited undo. This means you can undo the undo that undid a previous undo, and so on.

3.6.2 Undoing Into a Session

If semantic errors result from undoing a session activation, you are prevented from doing the undo. However there is an alternative in this case. You can undo the session activation and have the changes put into a new session. You can then fix the semantic errors and activate the session. You can also use this capability of undoing into a session to explore the ramifications of a session activation undo. You can examine all the changes that result, and decide if you really want to do the undo. If you decide that you really want to, you can activate the session.

3.7 Viewing Task Details

Use this page to view details of a specific change you made in the current session if you are in the session, and view details of specific changes you made in sessions that have been activated if you are outside a session.

1. Select View Changes under Change Center.
2. On the View Configuration Changes page, click the name of the task in the Task column. The Task Details page displays the information shown in Table 3-4.
   Table 3-4 Task Details

   Property	Description
   Task	The type of task you performed. Create Update Delete Rename Move
   Resource Type	The Oracle Service Bus resource types that were part of the task.
   Resource	The name and path of the resource. The path is the name of the project and folder in which the resource resides.

3. Click Back to return to the View Configuration Changes page.

3.8 Viewing All Sessions

Use this page to view all existing sessions within the Oracle Service Bus Administration Console. You can view these sessions if you are currently in a session or outside a session.

You can view all sessions only if you are using the Administrator role. For more information, see "Configuring Administrative Security" in the Oracle Fusion Middleware Developer's Guide for Oracle Service Bus.

1. Click View All Sessions under Change Center. For each existing session, the View All Sessions page displays the information shown in Table 3-5.
   Table 3-5 Session Details

   Property	Description
   Session Name	The name of the session. The name is a link to the session.
   User	The name of the user who created the session.
   Creation Time	The date and time the session was created.
   Last Modified	The date and time a change was last made during the session.
   # of Objects Modified	The number of objects that have been changed during the session.

2. To switch to another session, click the link in the Session Name column for that session.
   Note:

   The same user logged in with multiple browsers is not supported. It causes unpredictable behavior in the Administration Console.

3.9 Viewing and Resolving Conflicts

Use this page to view diagnostic messages about errors in your configuration, and to view and resolve conflicts between changes made in your session and other activated sessions. The view conflicts link also displays the number of live conflicts in the session.

Viewing Conflicts

1. Click View Conflicts under Change Center. The View Conflicts page can display any or all of the following sets of information depending on the nature of the conflicts:
   • Errors (an Error icon denotes non-committable, critical conflicts)—inform you of critical conflicts within your configuration. You cannot commit your changes without resolving the conflicts. See Table 3-6 and the next topic, "Resolving Conflicts."
   • Concurrent Updates (a Warning icon denotes committable, non-critical conflicts)—warn you about incompatible changes with other activated sessions. See Table 3-7.
   • Informational Messages (a Warning icon denotes committable, non-critical conflicts)—inform you of any non-critical conflicts within your configuration.
   Table 3-6 Errors

   Property	Description
   Name	The resource to which the error message refers. The name is a link to that resource.
   Path	The project and folder in which the resource resides.
   Resource Type	The resource type.
   Messages	A description of the conflict. To resolve the conflict, see "Resolving Conflicts" in the following section.

2. To display details of a specific conflict, click the link in the Name column for that conflict.
   If the object to which you make changes in a session has changed in the run time since you began the edit of the current session, the View Conflicts page displays the information shown in Table 3-7.

Table 3-7 Concurrent Updates

Property	Description
Name	The resource in conflict. The name is a link to that resource.
Your Changes	A description of the changes you made to this object in your session.
Other's Changes	A description of the changes another user made to this object in their session.
Synchronize	Click the Synchronize icon to return this object to the state in which it is saved in the run time.

Resolving Conflicts

To resolve a conflict, use the information provided in the Messages column (as described in Table 3-6) to understand the problem, and then edit the object that is causing the conflict to fix the problem.

For the scenario in which you have a concurrent update conflict—that is, a conflict that occurs if a resource is modified in the current session that has already been modified and activated by another session (as described in Table 3-7), you can resolve the conflict in one of two ways:

• Click Activate under Change Center. This saves your changes to the run time, which means you override changes that are deployed to core data by a previous session activation. In other words, the changes saved by the other user in another session are overwritten by your changes in this session.
• Click the Synchronize icon in the Synchronize column of the table (as described in Table 3-7). This action restores this object, in this session, to the state in which it was saved in the run time.