2.3 Using Oracle ORAchk to Confirm System Readiness for Implementing Application Continuity

Application Continuity Checking for Application Continuity allows you to deploy Application Continuity easily and transparently.

2.3.1 Overview of Application Continuity

Oracle ORAchk identifies any references to deprecated JDNVC concrete classes that need to be changed.

Oracle ORAchk analyzes the database operations in the application and reports the level of protection. It also reports where and why the applications are not protected.

Together, these checks can help you ensure that your application workload is covered by Oracle Application Continuity.

2.3.2 Checks for Application Continuity

Application Continuity Checking for Concrete Classes

Determine whether Java applications use deprecated Oracle JDBC concrete classes.

To use Application Continuity with Java, replace the deprecated Oracle JDBC concrete classes. For information about the deprecation of concrete classes including actions to take if an application uses them, see My Oracle Support Note 1364193.1.

To know if the application is using concrete classes, use Application Continuity checking (called acchk in Oracle ORAchk). There is no need to use 12c driver or database, or to have source code for concrete class checks. Verify the application in advance while planning for high availability for your application.

Application Continuity is unable to replay transactions that use oracle.sql deprecated concrete classes of the form ARRAY, BFILE, BLOB, CLOB, NCLOB, OPAQUE, REF, or STRUCT as a variable type, a cast, the return type of a method, or calling a constructor.

Modify them for Application Continuity to work with the application.

There are three values that control the Application Continuity checking for Oracle concrete classes. Set these values either on the command line, or through shell environment variables, or mixed. The values are as follows:

Table 2-1 Application Continuity Checking for Concrete Classes

Command-Line Argument Shell Environment Variable Usage

–asmhome jarfilename

RAT_AC_ASMJAR

This must point to a version of asm-all-5.0.3.jar that you download from ASM Home Page.

-javahome JDK8dirname

RAT_JAVA_HOME

This must point to the JAVA_HOME directory for a JDK8 installation.

-appjar dirname

RAT_AC_JARDIR

To analyze the application code for references to Oracle concrete classes, this must point to the parent directory name for the code. The program analyzes .class files, and recursively .jar files and directories.

Example Application Continuity Concrete Class Checks Summary

The following command checks the Application Continuity checking for Oracle concrete classes.

export RAT_AC_TRCDIR=/u01/app/oracle/diag/rdbms/dbname/instance1/trace
$ ./orachk -acchk -asmhome /path/orachk/asm-5.0.3/lib/all/asm-all-5.0.3.jar -javahome /usr/lib/jvm/jre-1.8.0-openjdk.x86_64
Outage Type              Status  Message

Concrete class checks    Total : 19845 Passed : 19610 Warning : 0 
                         Failed : 235 
                         (Failed check count is one per file)

                         FAILED	[oracle/jdbc/driver/ArrayDataResultSet]
                                 [[CAST]desc= oracle/sql/STRUCT method 
                                 name=getObject, lineno=1477]
                                    
                         FAILED	[oracle/jdbc/driver/ArrayDataResultSet]
                                 [[CAST]desc= oracle/sql/NCLOB method 
                                 name=getNClob, lineno=1776]
                                    
                         FAILED	[oracle/jdbc/driver/BfileAccessor]
                                 [[Method]name=getBFILE,
                                 desc=(I)Loracle/sql/BFILE;,
                                 lineno=99]
                                    
                         FAILED	[oracle/jdbc/driver/BlobAccessor]
                                 [[Method]name=getBLOB,
                                 desc=(I)Loracle/sql/BLOB;,
                                 lineno=129]
                                    
                         FAILED	[oracle/jdbc/driver/ClobAccessor]
                                 [[Method]name=getCLOB_,
                                 desc=(I[B)Loracle/sql/CLOB;,
                                 lineno=230]
                                    
                         FAILED	[oracle/jdbc/driver/ClobAccessor]
                                 [[Method] name=getCLOB,
                                 desc=(I)Loracle/sql/CLOB;, 
                                 lineno=226]

Application Continuity Checking for the Protection Level Application Continuity is Providing Your Application

Measure Coverage

Destructive testing is a good thing to do. However, introducing failures is non-deterministic. The application can fail over in all the tests, and then in production a failure occurs elsewhere and unexpectedly some requests do not fail over.

Using AC Check Coverage Analysis averts this situation by reporting in advance the percentage of requests that are fully protected by Application Continuity, and for the requests that are not fully protected, which they are and where. Use the coverage check before deployment, and the after application changes. Developers and management know how protected an application release is from failures of the underlying infrastructure. If there is a problem, then it can be fixed before the application is released or waived knowing the level of coverage.

Executing the coverage check is rather like using SQL_TRACE. First run the application in a representative test environment with Application Continuity trace turned on at the server side. The trace is collected in the standard database user trace directory in user trace files. Then, pass this directory as input to Oracle ORAchk to report the coverage for the application functions that were run. As this check uses Application Continuity, the database and client must be using 12c. The application need not necessarily released with Application Continuity. The check is to help you release.

The following is a summary of the coverage analysis.

  • If a round trip is made to the database server and returns while Application Continuity’ capture is enabled during capture phase, then it is counted as a protected call.

  • If a round trip is made to the database server while Application Continuity’ capture is disabled (not in a request, or following a restricted call or a disable replay API was called), then it is counted as an unprotected call.

  • Round trips ignored by capture and replay are ignored in the protection-level statistics.

    At the end of processing each trace file, a level of protection for the calls sent to the database is computed.

    For each trace: PASS (>= 75), WARNING (25 <= value <75), and FAIL (< 25)

Running the Coverage Report

  1. Turn on tracing at either a session level or database level.

    To enable for a single application function, run as follows (put this statement in the callback or before beginRequest so replay is not disabled by setting events):
    SQL> alter session set events 'trace [progint_appcont_rdbms]';
    Before running the workload, run the following statement as DBA on a test Oracle Database server so that the trace files include the needed information.
    SQL> alter system set event='10602 trace name context forever, level 28:trace[progint_appcont_rdbms]:10702 trace name context forever, level 16' scope = spfile ;
    SQL> shutdown immediate;
    SQL> startup;
  2. Run through the application functions. To report on an application function, the application function must be run. The more application functions run, the better the information that the coverage analysis provides.

  3. Use Oracle ORAchk to analyze the collected database traces and report the level of protection, and where not protected, reports why a request is not protected.

    To control the Application Continuity checking for coverage, set the following four values through command line or shell environment variables (or mixed):

    Table 2-2 Using Application Continuity Checking for Protection Level

    Command-Line Argument Shell Environment Variable Usage

    –asmhome jarfilename

    RAT_AC_ASMJAR

    This must point to a version of asm-all-5.0.3.jar that you download from ASM Home Page.

    -javahome JDK8dirname

    RAT_JAVA_HOME

    This must point to the JAVA_HOME directory for a JDK8 installation.

    -apptrc dirname

    RAT_AC_TRCDIR

    To analyze the coverage, specify a directory name that contains one or more database server trace files. The trace directory is generally,
    $ORACLE_BASE/diag/rdbms/{DB_UNIQUE_NAME}/$ORACLE_SID/trace

    NONE

    RAT_ACTRACEFILE_WINDOW

    When scanning the trace directory, this optional value limits the analysis to scanning to files created in the most recent specified number of days

Example Coverage Report

$ ./orachk -asmhome /tmp/asm-all-5.0.3.jar -javahome /tmp/jdk1.8.0_40 -apptrc $ORACLE_BASE/diag/rdbms/$ORACLE_SID/trace 3

Reading the Coverage Report

The coverage check produces a directory named orachk_uname_date_time. This report summaries coverage and lists trace files that have WARNINGS or FAIL status. To ensure all requests PASS (Coverage(%) = 100), check the PASS report, acchk_scorecard_pass.html in the reports directory. To see all the details, look for reports/acchk_scorecard_pass.html under the outfile subdirectory.

The output includes the database service name, the module name (from v$session.program, which can be set on the client side using the connection property on Java, for example, oracle.jdbc.v$session.program), the ACTION and CLIENT_ID, which can be set using setClientInfo with OCSID.ACTION and OCSID.CLIENTID respectively.

Example output: found in orachk_.....html#acchk_scorecard
Outage Type Status/Message

Coverage
checks      Total : 19845 Passed : 19610 Warning : 0
            Failed : 235
            (Failed check count is one per file)

            [FAIL] Trace file name = SAMPLE_ora_1234.trc 
            Row number = 2222
            SERVICE NAME = (SAMPLE_WEB_SERVICE.OCS.QA)
            MODULE NAME = (DEBIT)
            ACTION NAME = null
            CLIENT ID = null 
            Coverage(%) = 50 
            ProtectedCalls = 4 
            UnProtectedCalls = 4
					
            [FAIL] Trace file name = SAMPLE_ora_5678.trc 
            Row number = 7653
            SERVICE NAME = (SAMPLE_WEB_SERVICE.OCS.QA)
            MODULE NAME = (PAYMENTS)
            ACTION NAME = null 
            CLIENT ID = null 
            Coverage(%) = 20 
            ProtectedCalls = 1 
            UnProtectedCalls = 4
							
            [FAIL] Trace file name = SAMPLE_ora_90123.trc
            Row number = 15099
            SERVICE NAME = (SAMPLE_WEB_SERVICE.OCS.QA)
            MODULE NAME = (PAYMENTS)
            ACTION NAME = null 
            CLIENT ID = null 
            Coverage(%) = 60 
            ProtectedCalls = 3 
            UnProtectedCalls = 2
							
            [FAIL] Trace file name = SAMPLE_ora_4747.trc
            Row number = 789
            SERVICE NAME = (SAMPLE_WEB_SERVICE.OCS.QA)
            MODULE NAME = (ACCOUNT)
            ACTION NAME = null 
            CLIENT ID = null 
            Coverage(%) = 50  
            ProtectedCalls = 2 
            UnProtectedCalls = 2