The INVOKE and END-INVOKE statements represent sophisticated object-oriented programming constructs within modern COBOL environments, providing comprehensive method invocation capabilities that enable object interaction, dynamic method calling, and advanced exception handling. These statements embody the principles of object-oriented design by supporting polymorphism, encapsulation, and inheritance while maintaining type safety, ensuring proper method resolution, and facilitating robust object communication across enterprise applications requiring sophisticated object models, dynamic method dispatch, and comprehensive exception management with reliable execution patterns and optimized performance characteristics.
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657*> Basic INVOKE syntax INVOKE object-reference method-name [USING parameter-list] [RETURNING return-value] [ON EXCEPTION imperative-statements] [NOT ON EXCEPTION imperative-statements] END-INVOKE *> Static method invocation INVOKE class-name method-name [USING parameter-list] [RETURNING return-value] END-INVOKE *> Factory method invocation INVOKE class-name "NEW" [USING parameter-list] RETURNING object-reference END-INVOKE *> Self method invocation INVOKE SELF method-name [USING parameter-list] [RETURNING return-value] END-INVOKE *> Super method invocation INVOKE SUPER method-name [USING parameter-list] [RETURNING return-value] END-INVOKE *> Basic examples 01 WS-CUSTOMER-OBJECT OBJECT REFERENCE. 01 WS-RESULT PIC X(100). 01 WS-AMOUNT PIC 9(8)V99. PROCEDURE DIVISION. *> Create object instance INVOKE Customer "NEW" RETURNING WS-CUSTOMER-OBJECT *> Call instance method INVOKE WS-CUSTOMER-OBJECT "getName" RETURNING WS-RESULT *> Call method with parameters INVOKE WS-CUSTOMER-OBJECT "setBalance" USING WS-AMOUNT *> Method with exception handling INVOKE WS-CUSTOMER-OBJECT "processPayment" USING WS-AMOUNT ON EXCEPTION DISPLAY "Payment processing failed" NOT ON EXCEPTION DISPLAY "Payment processed successfully" END-INVOKE
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529530531532533534535536537538539540541542543544545546547548549550551552553554555556557558559560561562563564565IDENTIFICATION DIVISION. PROGRAM-ID. INVOKE-DEMONSTRATION. *> Object-oriented customer management example CLASS-ID. Customer. ENVIRONMENT DIVISION. CONFIGURATION SECTION. REPOSITORY. CLASS Customer. DATA DIVISION. WORKING-STORAGE SECTION. 01 WS-INSTANCE-DATA. 05 WS-CUSTOMER-ID PIC X(10). 05 WS-CUSTOMER-NAME PIC X(50). 05 WS-BALANCE PIC S9(10)V99. 05 WS-CREDIT-LIMIT PIC 9(10)V99. 05 WS-STATUS PIC X(10). OBJECT. DATA DIVISION. WORKING-STORAGE SECTION. 01 INSTANCE-VARIABLES. 05 CUSTOMER-ID PIC X(10). 05 CUSTOMER-NAME PIC X(50). 05 ACCOUNT-BALANCE PIC S9(10)V99. 05 CREDIT-LIMIT PIC 9(10)V99. 05 ACCOUNT-STATUS PIC X(10) VALUE "ACTIVE". PROCEDURE DIVISION. *> Constructor method METHOD-ID. "NEW". DATA DIVISION. LINKAGE SECTION. 01 LK-CUSTOMER-ID PIC X(10). 01 LK-CUSTOMER-NAME PIC X(50). 01 LK-CREDIT-LIMIT PIC 9(10)V99. PROCEDURE DIVISION USING LK-CUSTOMER-ID LK-CUSTOMER-NAME LK-CREDIT-LIMIT. MOVE LK-CUSTOMER-ID TO CUSTOMER-ID MOVE LK-CUSTOMER-NAME TO CUSTOMER-NAME MOVE LK-CREDIT-LIMIT TO CREDIT-LIMIT MOVE 0 TO ACCOUNT-BALANCE MOVE "ACTIVE" TO ACCOUNT-STATUS DISPLAY "Customer created: " CUSTOMER-NAME END METHOD "NEW". *> Getter methods METHOD-ID. "getName". DATA DIVISION. LINKAGE SECTION. 01 LK-RETURN-NAME PIC X(50). PROCEDURE DIVISION RETURNING LK-RETURN-NAME. MOVE CUSTOMER-NAME TO LK-RETURN-NAME END METHOD "getName". METHOD-ID. "getBalance". DATA DIVISION. LINKAGE SECTION. 01 LK-RETURN-BALANCE PIC S9(10)V99. PROCEDURE DIVISION RETURNING LK-RETURN-BALANCE. MOVE ACCOUNT-BALANCE TO LK-RETURN-BALANCE END METHOD "getBalance". METHOD-ID. "getStatus". DATA DIVISION. LINKAGE SECTION. 01 LK-RETURN-STATUS PIC X(10). PROCEDURE DIVISION RETURNING LK-RETURN-STATUS. MOVE ACCOUNT-STATUS TO LK-RETURN-STATUS END METHOD "getStatus". *> Setter methods METHOD-ID. "setName". DATA DIVISION. LINKAGE SECTION. 01 LK-NEW-NAME PIC X(50). PROCEDURE DIVISION USING LK-NEW-NAME. MOVE LK-NEW-NAME TO CUSTOMER-NAME DISPLAY "Customer name updated to: " CUSTOMER-NAME END METHOD "setName". *> Business logic methods METHOD-ID. "deposit". DATA DIVISION. LINKAGE SECTION. 01 LK-AMOUNT PIC 9(8)V99. 01 LK-SUCCESS-FLAG PIC X. PROCEDURE DIVISION USING LK-AMOUNT RETURNING LK-SUCCESS-FLAG. IF LK-AMOUNT > 0 ADD LK-AMOUNT TO ACCOUNT-BALANCE MOVE "Y" TO LK-SUCCESS-FLAG DISPLAY "Deposited $" LK-AMOUNT " New balance: $" ACCOUNT-BALANCE ELSE MOVE "N" TO LK-SUCCESS-FLAG DISPLAY "Invalid deposit amount: $" LK-AMOUNT END-IF END METHOD "deposit". METHOD-ID. "withdraw". DATA DIVISION. LINKAGE SECTION. 01 LK-AMOUNT PIC 9(8)V99. 01 LK-SUCCESS-FLAG PIC X. PROCEDURE DIVISION USING LK-AMOUNT RETURNING LK-SUCCESS-FLAG. IF LK-AMOUNT > 0 IF ACCOUNT-BALANCE + CREDIT-LIMIT >= LK-AMOUNT SUBTRACT LK-AMOUNT FROM ACCOUNT-BALANCE MOVE "Y" TO LK-SUCCESS-FLAG DISPLAY "Withdrew $" LK-AMOUNT " New balance: $" ACCOUNT-BALANCE ELSE MOVE "N" TO LK-SUCCESS-FLAG DISPLAY "Insufficient funds for withdrawal of $" LK-AMOUNT END-IF ELSE MOVE "N" TO LK-SUCCESS-FLAG DISPLAY "Invalid withdrawal amount: $" LK-AMOUNT END-IF END METHOD "withdraw". METHOD-ID. "transfer". DATA DIVISION. LINKAGE SECTION. 01 LK-AMOUNT PIC 9(8)V99. 01 LK-TARGET-CUSTOMER OBJECT REFERENCE. 01 LK-SUCCESS-FLAG PIC X. PROCEDURE DIVISION USING LK-AMOUNT LK-TARGET-CUSTOMER RETURNING LK-SUCCESS-FLAG. *> Withdraw from this account INVOKE SELF "withdraw" USING LK-AMOUNT RETURNING LK-SUCCESS-FLAG IF LK-SUCCESS-FLAG = "Y" *> Deposit to target account INVOKE LK-TARGET-CUSTOMER "deposit" USING LK-AMOUNT RETURNING LK-SUCCESS-FLAG IF LK-SUCCESS-FLAG = "Y" DISPLAY "Transfer completed successfully" ELSE *> Rollback withdrawal INVOKE SELF "deposit" USING LK-AMOUNT RETURNING LK-SUCCESS-FLAG MOVE "N" TO LK-SUCCESS-FLAG DISPLAY "Transfer failed - deposit to target failed" END-IF ELSE DISPLAY "Transfer failed - insufficient funds" END-IF END METHOD "transfer". METHOD-ID. "calculateInterest". DATA DIVISION. WORKING-STORAGE SECTION. 01 WS-INTEREST-RATE PIC 9V9999 VALUE 0.0325. 01 WS-INTEREST-AMOUNT PIC S9(8)V99. LINKAGE SECTION. 01 LK-RETURN-INTEREST PIC S9(8)V99. PROCEDURE DIVISION RETURNING LK-RETURN-INTEREST. IF ACCOUNT-BALANCE > 0 COMPUTE WS-INTEREST-AMOUNT = ACCOUNT-BALANCE * WS-INTEREST-RATE MOVE WS-INTEREST-AMOUNT TO LK-RETURN-INTEREST DISPLAY "Interest calculated: $" WS-INTEREST-AMOUNT ELSE MOVE 0 TO LK-RETURN-INTEREST END-IF END METHOD "calculateInterest". METHOD-ID. "closeAccount". PROCEDURE DIVISION. IF ACCOUNT-BALANCE = 0 MOVE "CLOSED" TO ACCOUNT-STATUS DISPLAY "Account closed for customer: " CUSTOMER-NAME ELSE DISPLAY "Cannot close account with balance: $" ACCOUNT-BALANCE END-IF END METHOD "closeAccount". END OBJECT. END CLASS Customer. *> Main program demonstrating INVOKE usage IDENTIFICATION DIVISION. PROGRAM-ID. CUSTOMER-DEMO. ENVIRONMENT DIVISION. CONFIGURATION SECTION. REPOSITORY. CLASS Customer. DATA DIVISION. WORKING-STORAGE SECTION. 01 WS-CUSTOMER-OBJECTS. 05 WS-CUSTOMER1 OBJECT REFERENCE. 05 WS-CUSTOMER2 OBJECT REFERENCE. 05 WS-CUSTOMER3 OBJECT REFERENCE. 01 WS-WORKING-FIELDS. 05 WS-CUSTOMER-NAME PIC X(50). 05 WS-BALANCE PIC S9(10)V99. 05 WS-AMOUNT PIC 9(8)V99. 05 WS-SUCCESS-FLAG PIC X. 05 WS-INTEREST PIC S9(8)V99. 05 WS-STATUS PIC X(10). 01 WS-DEMO-DATA. 05 WS-DEMO-CUSTOMERS. 10 FILLER PIC X(60) VALUE "CUST001ALICE JOHNSON 000500000". 10 FILLER PIC X(60) VALUE "CUST002BOB SMITH 001000000". 10 FILLER PIC X(60) VALUE "CUST003CAROL WILLIAMS 000750000". 05 WS-DEMO-TABLE REDEFINES WS-DEMO-CUSTOMERS. 10 WS-DEMO-ENTRY OCCURS 3 TIMES. 15 WS-DEMO-ID PIC X(7). 15 WS-DEMO-NAME PIC X(40). 15 WS-DEMO-LIMIT PIC 9(9)V99. 01 WS-COUNTERS. 05 WS-CUSTOMER-COUNT PIC 9(2) VALUE 0. 05 WS-TRANSACTION-COUNT PIC 9(4) VALUE 0. PROCEDURE DIVISION. MAIN-PROCESSING. PERFORM DEMONSTRATE-OBJECT-CREATION PERFORM DEMONSTRATE-BASIC-OPERATIONS PERFORM DEMONSTRATE-BUSINESS-LOGIC PERFORM DEMONSTRATE-EXCEPTION-HANDLING PERFORM DEMONSTRATE-POLYMORPHIC-BEHAVIOR PERFORM CLEANUP-OBJECTS STOP RUN. DEMONSTRATE-OBJECT-CREATION. DISPLAY "=== OBJECT CREATION WITH INVOKE ===" *> Create customer objects using constructor INVOKE Customer "NEW" USING "CUST001" "ALICE JOHNSON" 5000.00 RETURNING WS-CUSTOMER1 ON EXCEPTION DISPLAY "Error creating customer 1" NOT ON EXCEPTION ADD 1 TO WS-CUSTOMER-COUNT DISPLAY "Customer 1 created successfully" END-INVOKE INVOKE Customer "NEW" USING "CUST002" "BOB SMITH" 10000.00 RETURNING WS-CUSTOMER2 ON EXCEPTION DISPLAY "Error creating customer 2" NOT ON EXCEPTION ADD 1 TO WS-CUSTOMER-COUNT DISPLAY "Customer 2 created successfully" END-INVOKE INVOKE Customer "NEW" USING "CUST003" "CAROL WILLIAMS" 7500.00 RETURNING WS-CUSTOMER3 ON EXCEPTION DISPLAY "Error creating customer 3" NOT ON EXCEPTION ADD 1 TO WS-CUSTOMER-COUNT DISPLAY "Customer 3 created successfully" END-INVOKE DISPLAY "Total customers created: " WS-CUSTOMER-COUNT DISPLAY SPACES. DEMONSTRATE-BASIC-OPERATIONS. DISPLAY "=== BASIC OBJECT OPERATIONS ===" *> Get customer information INVOKE WS-CUSTOMER1 "getName" RETURNING WS-CUSTOMER-NAME INVOKE WS-CUSTOMER1 "getBalance" RETURNING WS-BALANCE INVOKE WS-CUSTOMER1 "getStatus" RETURNING WS-STATUS DISPLAY "Customer 1 Details:" DISPLAY " Name: " WS-CUSTOMER-NAME DISPLAY " Balance: $" WS-BALANCE DISPLAY " Status: " WS-STATUS *> Perform basic transactions MOVE 1000.00 TO WS-AMOUNT INVOKE WS-CUSTOMER1 "deposit" USING WS-AMOUNT RETURNING WS-SUCCESS-FLAG ON EXCEPTION DISPLAY "Deposit operation failed" NOT ON EXCEPTION IF WS-SUCCESS-FLAG = "Y" ADD 1 TO WS-TRANSACTION-COUNT DISPLAY "Deposit successful" ELSE DISPLAY "Deposit rejected" END-IF END-INVOKE MOVE 250.00 TO WS-AMOUNT INVOKE WS-CUSTOMER1 "withdraw" USING WS-AMOUNT RETURNING WS-SUCCESS-FLAG ON EXCEPTION DISPLAY "Withdrawal operation failed" NOT ON EXCEPTION IF WS-SUCCESS-FLAG = "Y" ADD 1 TO WS-TRANSACTION-COUNT DISPLAY "Withdrawal successful" ELSE DISPLAY "Withdrawal rejected" END-IF END-INVOKE DISPLAY SPACES. DEMONSTRATE-BUSINESS-LOGIC. DISPLAY "=== BUSINESS LOGIC OPERATIONS ===" *> Customer 2 operations MOVE 2000.00 TO WS-AMOUNT INVOKE WS-CUSTOMER2 "deposit" USING WS-AMOUNT RETURNING WS-SUCCESS-FLAG *> Transfer between customers MOVE 500.00 TO WS-AMOUNT INVOKE WS-CUSTOMER2 "transfer" USING WS-AMOUNT WS-CUSTOMER1 RETURNING WS-SUCCESS-FLAG ON EXCEPTION DISPLAY "Transfer operation encountered exception" NOT ON EXCEPTION IF WS-SUCCESS-FLAG = "Y" ADD 1 TO WS-TRANSACTION-COUNT DISPLAY "Transfer completed successfully" ELSE DISPLAY "Transfer failed" END-IF END-INVOKE *> Calculate interest for all customers INVOKE WS-CUSTOMER1 "calculateInterest" RETURNING WS-INTEREST DISPLAY "Customer 1 Interest: $" WS-INTEREST INVOKE WS-CUSTOMER2 "calculateInterest" RETURNING WS-INTEREST DISPLAY "Customer 2 Interest: $" WS-INTEREST INVOKE WS-CUSTOMER3 "calculateInterest" RETURNING WS-INTEREST DISPLAY "Customer 3 Interest: $" WS-INTEREST DISPLAY SPACES. DEMONSTRATE-EXCEPTION-HANDLING. DISPLAY "=== EXCEPTION HANDLING ===" *> Test insufficient funds scenario MOVE 20000.00 TO WS-AMOUNT INVOKE WS-CUSTOMER1 "withdraw" USING WS-AMOUNT RETURNING WS-SUCCESS-FLAG ON EXCEPTION DISPLAY "Exception occurred during large withdrawal" PERFORM HANDLE-WITHDRAWAL-EXCEPTION NOT ON EXCEPTION IF WS-SUCCESS-FLAG = "Y" DISPLAY "Large withdrawal successful" ELSE DISPLAY "Large withdrawal rejected - business rules" END-IF END-INVOKE *> Test invalid amount scenario MOVE -100.00 TO WS-AMOUNT INVOKE WS-CUSTOMER1 "deposit" USING WS-AMOUNT RETURNING WS-SUCCESS-FLAG ON EXCEPTION DISPLAY "Exception occurred with negative deposit" PERFORM HANDLE-DEPOSIT-EXCEPTION NOT ON EXCEPTION DISPLAY "Negative deposit processed (unexpected)" END-INVOKE DISPLAY SPACES. HANDLE-WITHDRAWAL-EXCEPTION. DISPLAY "Handling withdrawal exception..." DISPLAY " Logging transaction attempt" DISPLAY " Notifying customer of failure" DISPLAY " Updating audit trail". HANDLE-DEPOSIT-EXCEPTION. DISPLAY "Handling deposit exception..." DISPLAY " Validating transaction data" DISPLAY " Recording error details". DEMONSTRATE-POLYMORPHIC-BEHAVIOR. DISPLAY "=== POLYMORPHIC BEHAVIOR ===" *> Process multiple customers using same interface PERFORM PROCESS-CUSTOMER-ACCOUNT USING WS-CUSTOMER1 PERFORM PROCESS-CUSTOMER-ACCOUNT USING WS-CUSTOMER2 PERFORM PROCESS-CUSTOMER-ACCOUNT USING WS-CUSTOMER3 DISPLAY SPACES. PROCESS-CUSTOMER-ACCOUNT USING LK-CUSTOMER. LINKAGE SECTION. 01 LK-CUSTOMER OBJECT REFERENCE. PROCEDURE DIVISION. *> Same method calls work on any customer object INVOKE LK-CUSTOMER "getName" RETURNING WS-CUSTOMER-NAME INVOKE LK-CUSTOMER "getBalance" RETURNING WS-BALANCE INVOKE LK-CUSTOMER "getStatus" RETURNING WS-STATUS DISPLAY "Processing account for: " WS-CUSTOMER-NAME DISPLAY " Current balance: $" WS-BALANCE DISPLAY " Account status: " WS-STATUS *> Apply interest if balance is positive IF WS-BALANCE > 0 INVOKE LK-CUSTOMER "calculateInterest" RETURNING WS-INTEREST DISPLAY " Interest earned: $" WS-INTEREST END-IF. CLEANUP-OBJECTS. DISPLAY "=== CLEANUP AND SUMMARY ===" *> Close accounts with zero balance INVOKE WS-CUSTOMER1 "getBalance" RETURNING WS-BALANCE IF WS-BALANCE = 0 INVOKE WS-CUSTOMER1 "closeAccount" END-IF INVOKE WS-CUSTOMER2 "getBalance" RETURNING WS-BALANCE IF WS-BALANCE = 0 INVOKE WS-CUSTOMER2 "closeAccount" END-IF INVOKE WS-CUSTOMER3 "getBalance" RETURNING WS-BALANCE IF WS-BALANCE = 0 INVOKE WS-CUSTOMER3 "closeAccount" END-IF *> Set object references to NULL for cleanup SET WS-CUSTOMER1 TO NULL SET WS-CUSTOMER2 TO NULL SET WS-CUSTOMER3 TO NULL DISPLAY "Total transactions processed: " WS-TRANSACTION-COUNT DISPLAY "Objects cleaned up successfully". *> Advanced INVOKE patterns ADVANCED-INVOKE-PATTERNS. DISPLAY "=== ADVANCED INVOKE PATTERNS ===" PERFORM DEMONSTRATE-FACTORY-METHODS PERFORM DEMONSTRATE-STATIC-METHODS PERFORM DEMONSTRATE-CHAINED-INVOCATIONS PERFORM DEMONSTRATE-CONDITIONAL-INVOCATION. DEMONSTRATE-FACTORY-METHODS. DISPLAY "Factory Method Pattern:" *> Using factory methods for object creation INVOKE Customer "createPremiumCustomer" USING "PREM001" "PREMIUM USER" 50000.00 RETURNING WS-CUSTOMER1 ON EXCEPTION DISPLAY "Factory method failed" NOT ON EXCEPTION DISPLAY "Premium customer created via factory" END-INVOKE. DEMONSTRATE-STATIC-METHODS. DISPLAY "Static Method Calls:" *> Call static utility methods INVOKE Customer "validateCustomerId" USING "CUST001" RETURNING WS-SUCCESS-FLAG IF WS-SUCCESS-FLAG = "Y" DISPLAY "Customer ID validation passed" ELSE DISPLAY "Customer ID validation failed" END-IF. DEMONSTRATE-CHAINED-INVOCATIONS. DISPLAY "Method Chaining Simulation:" *> Simulate fluent interface pattern INVOKE WS-CUSTOMER1 "deposit" USING 1000.00 RETURNING WS-SUCCESS-FLAG IF WS-SUCCESS-FLAG = "Y" INVOKE WS-CUSTOMER1 "calculateInterest" RETURNING WS-INTEREST INVOKE WS-CUSTOMER1 "deposit" USING WS-INTEREST RETURNING WS-SUCCESS-FLAG END-IF. DEMONSTRATE-CONDITIONAL-INVOCATION. DISPLAY "Conditional Method Invocation:" INVOKE WS-CUSTOMER1 "getStatus" RETURNING WS-STATUS EVALUATE WS-STATUS WHEN "ACTIVE" INVOKE WS-CUSTOMER1 "calculateInterest" RETURNING WS-INTEREST DISPLAY "Active account - interest calculated" WHEN "DORMANT" INVOKE WS-CUSTOMER1 "activateAccount" DISPLAY "Dormant account activated" WHEN "CLOSED" DISPLAY "Account is closed - no operations allowed" WHEN OTHER DISPLAY "Unknown account status: " WS-STATUS END-EVALUATE. ERROR-RECOVERY-PATTERNS. DISPLAY "=== ERROR RECOVERY PATTERNS ===" *> Retry pattern with INVOKE PERFORM RETRY-INVOKE-OPERATION *> Circuit breaker pattern simulation PERFORM CIRCUIT-BREAKER-INVOKE. RETRY-INVOKE-OPERATION. MOVE 3 TO WS-CUSTOMER-COUNT *> Retry counter PERFORM UNTIL WS-CUSTOMER-COUNT = 0 OR WS-SUCCESS-FLAG = "Y" INVOKE WS-CUSTOMER1 "complexOperation" RETURNING WS-SUCCESS-FLAG ON EXCEPTION SUBTRACT 1 FROM WS-CUSTOMER-COUNT DISPLAY "Retry attempt remaining: " WS-CUSTOMER-COUNT NOT ON EXCEPTION IF WS-SUCCESS-FLAG = "Y" DISPLAY "Operation succeeded after retry" ELSE SUBTRACT 1 FROM WS-CUSTOMER-COUNT END-IF END-INVOKE END-PERFORM IF WS-SUCCESS-FLAG NOT = "Y" DISPLAY "Operation failed after all retries" END-IF. CIRCUIT-BREAKER-INVOKE. *> Simulate circuit breaker pattern IF WS-TRANSACTION-COUNT < 10 *> Circuit open DISPLAY "Circuit breaker OPEN - operation blocked" ELSE INVOKE WS-CUSTOMER1 "riskyOperation" ON EXCEPTION DISPLAY "Circuit breaker triggered" MOVE 0 TO WS-TRANSACTION-COUNT *> Open circuit NOT ON EXCEPTION DISPLAY "Risky operation succeeded" END-INVOKE END-IF.
What is the primary purpose of INVOKE and END-INVOKE?
Answer: INVOKE and END-INVOKE are used in Object-Oriented COBOL to call methods on object instances, handle method parameters and return values, and manage exceptions that may occur during method execution.
How do you handle exceptions in INVOKE statements?
Answer: Use ON EXCEPTION clause within the INVOKE statement to handle method execution errors, and NOT ON EXCEPTION for successful execution. END-INVOKE marks the end of the exception handling block.
What types of methods can be called with INVOKE?
Answer: INVOKE can call instance methods on objects, static methods on classes, factory methods (like "NEW"), self-referential methods (SELF), and inherited methods (SUPER).