Application Engine Actions

古城微笑少年丶 2021-12-15 02:51 324阅读 0赞

**Specifying SQL Actions**

ReUse Statement Property

The ReUse Statement property is available for all SQL action types (SQL, Do When, Do While, Do Until, Do Select). You use the ReUse Statement property to optimize the SQL in your batch program. ReUse Statement converts any %BIND references to state record fields into real bind variables (:1, :2, and so on), enabling the Application Engine runtime process to compile the statement once, dedicate a cursor, and then re-execute it with new data as often as your program requires. When you are using SQL or a Do action to process a large volume of rows, one at a time, inside a fetch loop, compiling each statement that you issue can be a considerable performance issue. ReUse Statement is a way to combat potential performance decreases.

When setting the ReUse Statement option, choose between these values:

<table> 
 <tbody> 
 <tr> 
 <td> Bulk Insert<a rel="nofollow"></a></td> 
 <td> When used in conjunction with statements like INSERT INTO tablename (field1, field2...) VALUES (%BIND(ref1), %BIND(ref2), the Bulk Insert feature offers the most powerful degree of performance enhancements related to the ReUse Statement feature. This option turns on ReUse Statement, and, in addition, it holds all the data in a buffer and performs an insert only after a large volume of rows has gathered in the buffer. The number of rows allowed to gather in the buffer depends on your database platform. Storing data in the buffers is applicable only if you’ve selected Bulk Insert and the SQL is an Insert statement. For statements other than Insert, the Bulk Insert option is ignored. </td> 
 </tr> 
 <tr> 
 <td> No</td> 
 <td> Select this option to disable ReUse Statement. With ReUse off, the Application Engine runtime process recompiles the SQL statement every time the loop executes. By default, ReUse Statement is disabled. </td> 
 </tr> 
 <tr> 
 <td> Yes</td> 
 <td> Select this option to enable basic ReUse Statement functionality.</td> 
 </tr> 
 </tbody> 
</table>

**No Rows Property**

In addition to the ReUse Statement property, the No Rows property is available for SQL actions. If the SQL (Insert, Update, or Delete) associated with the SQL action does not return any rows, you must specify what the Application Engine program should do.

For example, you could use this in a case where you insert into a temporary table, and then you intend to perform further operations on the inserted rows (provided that some rows meet the criteria). If the initial combination of Insert and Select statements provides no rows, you could save the program from having to reselect on the temporary table prior to executing another operation, or you could also prevent the program from performing set operations on the table when there won't be any qualifying rows.

When you set the No Rows property, you choose from the following values:

<table> 
 <tbody> 
 <tr> 
 <td> Abort</td> 
 <td> The program terminates.</td> 
 </tr> 
 <tr> 
 <td> Section Break</td> 
 <td> PeopleSoft Application Engine exits the current section immediately, and control returns to the calling step.</td> 
 </tr> 
 <tr> 
 <td> Continue</td> 
 <td> The program continues processing.</td> 
 </tr> 
 <tr> 
 <td> Skip Step</td> 
 <td> PeopleSoft Application Engine exits the current step immediately and moves on to the next step. Application Engine ignores the commit for the current step at runtime. If the current step contains only one action, use Skip Step only to bypass the commit. </td> 
 </tr> 
 </tbody> 
</table>

**Specifying Do Actions**

Do When

When using a Do When action, consider the following:

· The Do When action is a Select statement that allows subsequent actions to be executed if any rows of data are returned.

·This action is similar to a COBOL If statement.

A Do When statement runs before any other actions in the step. If the Do When statement returns any rows, the next action is executed. If the Do When conditions are not met, the remaining actions within that step are not executed. Your program executes a Do When action only once when the owning step executes.

·The only property that you can specify for the Do When action is the ReUse Statement property, which applies to all SQL-based actions.

Do While

The Do While action is a Select statement that, if present, runs before subsequent actions of the step. If the Do While does not return any rows of data, the action terminates. The Do While is identical to the COBOL While statement. Subsequent actions within the step are executed in a loop as long as at least one row is returned by the Select statement for the Do While action. If the Do While does not return any rows, the step is complete.

The only property that you can specify for the Do While action is the ReUse Statement property, which applies to all SQL-based actions.

Do Until

A Do Until action is a Select statement that runs after each action when a step completes. If the Select statement returns any rows of data, the step terminates.

·Use a Do Until action if you want the processing actions to execute at least once, and to execute over and over until a certain condition is true, such as until a Select statement returns some rows.

·You can also use a Do Until action to stop a Do Select action prematurely.

For example, if the Select statement for the Do Until action does not return any rows, then the actions in the step are repeated (except if a Do When action appears in the step). Normally, a Do Select action continues until no rows are returned. If any rows of data are returned, the Do Select action stops and the step is not repeated.

·The only property that you can specify for the Do Until action is the ReUse Statement property, which applies to all SQL-based actions.

Do Select

The Do Select action is a Select statement that executes subsequent actions once for every row of data that the Do Select returns. For instance, a Do Select can execute a SQL statement for each row returned from the Select statement. The subsequent actions within the step are executed in a loop based on the results of the Select statement. The type of the Do Select determines the specific looping rules.

Like the other Do actions, for the Do Select action you can specify the ReUse Statement property, which applies to all SQL-based actions.

In addition to the ReUse Statement property, you must also specify another Do Select property: *Do Select Type*.

**Do Select Type Property**

When you specify the Do Select Type property in a Do Select action, you choose from the following values:

<table> 
 <tbody> 
 <tr> 
 <td> Select/Fetch<a rel="nofollow"></a></td> 
 <td> PeopleSoft Application Engine opens a cursor for the Do Select action, then, within that cursor, PeopleSoft Application Engine performs a Fetch statement for each iteration of the loop to get each row from the Select statement. When a Fetch statement results in an end of table message, the looping is complete. You can’t restart this type of Select statement, because PeopleSoft Application Engine does not perform a checkpoint or a commit within the step containing this action while Select/Fetch is running. Ultimately, your program ignores the commit settings at runtime until the outermost Select/Fetch completes. 
 <div style="border-right:#b9b83e 1pt solid;border-top:#b9b83e 1pt solid;background:#fcfcc8;border-left:#b9b83e 1pt solid;border-bottom:#b9b83e 1pt solid;"> 
 Note. When an Application Engine program is not set up for restartability, then commits are not controlled, monitored, or restricted by PeopleSoft Application Engine. When Restart is disabled, commits are controlled by the program. 
 </div></td> 
 </tr> 
 <tr> 
 <td> Re-Select</td> 
 <td> For each iteration of the loop, PeopleSoft Application Engine opens a cursor and fetches the first row. Your program processes the first row returned from the Select statement. The cursor is reopened for each iteration of the loop. With this type of Fetch statement, you typically want some aspect of the loop to eventually cause the Select statement to return no rows. Otherwise, there is no mechanism in place by which to exit the loop. This type of Do Select is restartable. </td> 
 </tr> 
 <tr> 
 <td> Restartable</td> 
 <td> This option is similar to Select/Fetch in that PeopleSoft Application Engine opens the cursor associated with the Do Select action once, and then it performs a Fetch statement on each iteration of the loop to get each row from the Select statement. However, unlike the Select/Fetch option, you can restart this action, because PeopleSoft Application Engine performs a checkpoint in the middle of the step. PeopleSoft Application Engine treats this loop as if it is restartable, but it does not manage the restart. Make sure that the SQL you include within this action is such that, upon restart, the program recognizes where the previous run failed and where to restart processing. For example, you can employing a processed switch, or base the next Select statement on the key. </td> 
 </tr> 
 </tbody> 
</table>

**Specifying PeopleCode Actions**

Use this action type to insert PeopleCode within your Application Engine program. You can invoke the PeopleCode Editor directly from the designer interface to code your PeopleCode programs.

With a PeopleCode action, there is only one property that you can specify—On Return.

Use the On Return value to determine how your Application Engine program reacts based on the return of your PeopleCode program. **The On Return setting takes effect if your PeopleCode program issues a “return 1” or “exit 1.” You can use the True keyword in place of a non-zero numeric return.**

When you specify the On Return property, you choose from the following values:

<table> 
 <tbody> 
 <tr> 
 <td> Abort</td> 
 <td> The program issues an error and exits immediately.</td> 
 </tr> 
 <tr> 
 <td> Break</td> 
 <td> The program exits the current step and section, and control returns to the calling step.</td> 
 </tr> 
 <tr> 
 <td> Skip Step</td> 
 <td> The program exits the current step, and continues processing at the next step in the section. If this is the last step in the section, the calling step resumes control of the processing. </td> 
 </tr> 
 </tbody> 
</table>

**Specifying Call Section Actions**

Use the Call Section action to call another section defined in an Application Engine program. You can call a local section defined within your current program, and you can make external calls to a section defined in another Application Engine program.

The external section you intend to call must have its access property set to Public. If a section’s access property is set to Private, that section can be called only from within the same program. By default, a section’s access property is Private. If you attempt to make a call to a section that does not allow external calls, you receive an error message at runtime.

**Note.** You can call only programs that reside within the same database as the calling program.

Program ID Property

Because you can call sections defined in the current program or within external programs, you must first specify the program ID of the program containing the section you intend to call.

The default value is (current). If you call a section defined in another program, make sure that you first select the appropriate external program from the Program ID drop-down list box. The drop-down list box contains the names of all program definitions that currently exist in the database.

Section Name Property

Select from names defined in the program that appears in the Program ID list box. To call a section that is defined in an external program, select the program name in the Program ID edit box prior to selecting the section name.

Also use the Call Section action to call an entire external program. First select the program ID, then select section name MAIN. At runtime, this call executes the entire program defined by the value in the Program ID field.

**Specifying Log Message Actions**

Use this type of action to write a message to the message log. The message log refers to the PeopleTools table (PS\_MESSAGE\_LOG) where execution messages reside. Any substitution parameters are written to PS\_MESSAGE\_LOGPARM. The following illustration shows a Log Message action:

Log Message action

You can use the Log Message action to insert any type of messages. Typically, a Log Message action writes error messages to the message log, but you could also write informational or status messages.

**Note.** You can also use MessageBox PeopleCode to populate PS\_MESSAGE\_LOG instead of using the Log Message action. This enables you to easily record errors encountered within Application Engine PeopleCode programs.

<table> 
 <tbody> 
 <tr> 
 <td> Message Set and Number</td> 
 <td> Select the message defined in the message catalog.</td> 
 </tr> 
 <tr> 
 <td> Parameters</td> 
 <td> Enter values to insert in the log message. This field should be a comma-delimited list of values to substitute for the message variables (%1, %2, and so on) in the message text. These parameters can be hard-coded values or %Bind references. The information specified is inserted in the PS_MESSAGE_LOG at runtime, and any %Bind values are replaced by the current state record field values. You can then view the logged messages from the Process Monitor page. </td> 
 </tr> 
 </tbody> 
</table>

For example, using message set 1012, number 10, the message reads "The total number of %1 rows exceeds the control count value, %2,” and you need the following parameters:

Invoice, %Bind(CONTROL\_CNT)

Suppose you run this program with the CONTROL\_CNT field value of 120. When the process ends, the following message would be included on the Process Details dialog box in Process Monitor: “The total number of Invoice rows exceeds the control count value, 120.”

转载于:https://www.cnblogs.com/GoDevil/archive/2009/07/24/1530170.html