PQ55873: NEW FUNCTION

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APAR status
Closed as program error.

Error description
New Function
Local fix Problem summary
****************************************************************
* USERS AFFECTED: All users of WebSphere Application Server    *
*                 V4.0.1 for z/OS and OS/390.                  *
****************************************************************
* PROBLEM DESCRIPTION: The following problems are addressed    *
*                      in APAR PQ55873:                        *
*                                                              *
*                      New connector support is provided to    *
*                      support the following connectors which  *
*                      implement the J2EE Connector            *
*                      Architecture (JCA) and support 2-phase  *
*                      commit transaction processing through   *
*                      the use of zOS Resource Recovery        *
*                      Services (RRS):                         *
*                        - IMS Connect 1.2,                    *
*                          IMS Connector for Java              *
*                        - CICS Transaction Gateway (CTG)      *
*                          4.02 ECI Connector                  *
*                        - IMS 7.1 JDBC Connector              *
*                                                              *
*                      In addition to the new connector        *
*                      support, new Container concurrency      *
*                      control and isolation level support     *
*                      is provided for Container Managed       *
*                      Persistent (CMP) Entity Beans.          *
*                      Currently, only one concurrency         *
*                      control scheme with a single            *
*                      isolation level is provided in          *
*                      WebSphere Application Server for z/OS   *
*                      and OS/390 Version 4.0.1.  With the new *
*                      support, developers can now choose      *
*                      between two schemes of concurrency      *
*                      control support and can now specify the *
*                      particular isolation level they require *
*                      for their application.                  *
*                                                              *
*                      Solutions to the following defects and  *
*                      field-reported problems are also        *
*                      provided in APAR PQ55873:               *
*                                                              *
*                      (MD11251) ABEND0C4/ABENDS0C4 can occur  *
*                      in Snoozer::invokeSnoozeAlarm().        *
*                                                              *
*                      (MD13100) Support is needed to limit    *
*                      the number of server regions created by *
*                      WLM.                                    *
*                                                              *
*                      (
PQ52868) Customer reported running     *
*                      out of DB2 connections running a        *
*                      transaction that made multiple calls    *
*                      to CMP beans.                           *
*                                                              *
*                      (
PQ53749) A J2EE application under      *
*                      one transaction repeatedly invokes a    *
*                      session bean to access data on DB2 and  *
*                      runs out of DB2 connections (threads).  *
*                                                              *
*                      (
PQ56914) Sometimes, while deploying an *
*                      EAR file into SM/EUI, EarFileProcessing *
*                      fails.  NoClassDefFoundError is thrown  *
*                      for missing class, although the class   *
*                      that it claims is missing is contained  *
*                      within the WAR file's /WEB-INF/lib dir, *
*                      another EjbJAR file's / dir, or EAR     *
*                      file's / dir as a jar file.             *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************
The following problems are addressed in APAR PQ55873:

Connection Management support is provided by WebSphere for z/OS
to support selected CICS and IMS RRS-Compliant connectors which
implement the J2EE Connector Architecture. The Connection
Management support provides the application server support
needed by the connectors. With this capability, the supported
connectors can be used as either non-managed connectors or as
"managed connectors".  In this case:  JNDI Lookup support is
provided to locate connection factories requested by an
application; requested connections are managed by the server;
user identity assigned to each connection can be controlled by
the server or the application; Connection Management policy can
be specified to control the cleanup of connections that are not
properly closed by an applicaton, and support is provided to
reuse connections within a transaction. In conjunction with the
Connection Management support, WebSphere DB2 JDBC support is
also enhanced. When Connection Management is configured into the
servers, all DB2 JDBC connections are wrappered and managed as
J2EE connections. Additionally, with or without Connection
Management, DB2 JDBC connections are optionally reused within
the scope of a transaction to prevent the consumption of
critical DB2 resources (i.e., DB2 threads).

Concurrency Control is used by WebSphere to govern the manner in
which backend resource managers manage concurrent access to
data. Different applications may have varying requirements on
the scheme of Concurrency Control used by the resource manager.
There is a lack of control over what type of Concurrency Control
scheme is used and how much locking is done in the backend
during transactions. For some applications, a higher degree of
locking is necessary to ensure data integrity during frequent,
concurrent data access. In others, a lesser degree of locking
may be acceptable because of infrequent concurrent access to the
data. The current Concurrency Control Management system only
offers a "Pessimistic" scheme with a single Isolation Level.

Solutions to the following defects and field-reported problems
have also been provided in APAR PQ55873:

(MD11251) ABEND0C4/ABENDS0C4 can occur in
Snoozer::invokeSnoozeAlarm(). Timing windows exist in the
Snoozer / SnoozeAlarm (bbootmq.cpp, bbootmqe.cpp) classes that
can lead to references to objects that have already been freed.

(MD13100) Support is needed to limit the number of server
regions created by WLM. WLM will start server regions as it
feels they are necessary; however, there are conditions under
which it may be desirable to limit the number started.  An
interface needs to be provided to do this.

(
PQ52868) An application that calls a session bean that uses
tx required as a transaction attribute, and calls several CMPs
that have the same transaction attribute, eventually stops
working when it runs out of DB2 threads.  The customer sees from
200-300 connections made. Each CMP entity bean was using 2
connections per transaction.  When the customer increased the
max connections setting to 500, the number of connections did
not grow much beyond 300.

(
PQ53749) When a session EJB that gets, uses, and closes a
connection  to a DB2 JDBC DataSource is invoked repeatedly by
another EJB running under a single global transaction, a new
DB2 connection is created every time it is invoked and the new
connection ties up a DB2 thread until the transaction is
committed. As the EJB is invoked again and again under one
transaction, the available DB2 theads will be consumed, one by
one, until DB2 finally runs out of threads. This results in
an 0C2 abend.

(
PQ56914) In rare cases, an EAR file that contains both
EjbJARs and WARs may experience false claims of missing class,
even though the class that AAT/390 claims missing is, in fact,
located within /WEB-INF/lib dir as a jar file within WAR,
/ dir as a jar file within another EjbJAR, or / dir as a jar
file within EAR.

For example:
If an EAR that a user is trying to import into AAT/390 has the
following structure, while AAT tries to reflect all methods
of Hello EJB stored within an EjbJAR file, the classloader
mechanism used within AAT may face the following problem:
=> inherits/extends
-> references

Trying to reflect all methods in HelloHome interface will cause
HelloRemote class to be loaded due to reference. HelloRemote
extends Hello class; therefore, Hello gets loaded under the
cover. Hello residing in war1.war->WEB-INF/lib/WarClasses.jar
references several classes, including the following:

EmployeeInformationValue.class, TargetEntitlement.class
GrndsFactoryException.class

s1.ear: META-INF/application.xml
        ejb1.jar       (EjbJAR)
        web1.war       (WebApp)

        ejb1.jar: META-INF/ejb-jar.xml
                  com/s1/HelloRemote.class  => Hello.class
                  com/s1/HelloBean.class
                  com/s1/HelloHome.class    -> HelloRemote.class
                  :

        war1.war: WEB-INF/web.xml
                  WEB-INF/classes/com/s1/HelloServlet.class
                  WEB-INF/lib/WarClasses.jar
                  WEB-INF/lib/grnds_s1.jar
                  Hello.html
                  pretty.gif
                  :
                  WarClasses.jar: com/s1/Hello.class
                              +-> EmployeeInformationValue.class
                              +-> TargetEntitlement.class
                              +-> GrndsFactoryException.class
                     com/s1/EmployeeInformationValue.class
                     com/s1/TargetEntitlement.class
                     :

              grnds_s1.jar: org/grnds/GrndsFactoryException
                     :

NoClassDefFoundError is thrown for GrndsFactoryException, which
is NOT included within the same JAR as the first two classes
that Hello.class references due to the current classloader's
inability to delegate classes not found during classloading
between sibling Jar/Zip files contained within a J2EE Module
archive (i.e., EjbJAR, WAR, etc.).*
Problem conclusion
APAR PQ55873 provides the following problem resolution:

Connection Management support needed for J2EE connectors is now
included in the base WebSphere Application Server product for
z/OS and OS/390. A prior version of Connection Management had
been available only on the WebSphere Web site.

New Systems Management EUI support is provided to allow an
installation to configure Connection Management into the
Application Servers.

Connection Management has been enhanced to support the following
connectors:
  - 1.2 IMS Connector for Java
  - CICS Transaction Gateway (CTG) 4.02 ECI Connector
  - 7.1 IMS JDBC Connector

When Connection Management is configured into the Application
Servers, DB2 JDBC connections are wrappered as J2EE connections,
thus benefiting from the functional characteristics that are
implemented for standard J2EE connectors. Furthermore, with or
without Connection Management configured, customers can
optionally take advantage of connection reuse support to reuse
DB2 JDBC connections within the scope of a transaction, thus
avoiding the potential problem of running out DB2 threads during
application processing.

Support has been provided to allow application developers to
choose between two different schemes of Concurrency Control:
Pessimistic or Optimistic. In addition to the Pessimistic
scheme, the application developer can now specify which JDBC
Isolation Level they want applied to the backend connection, on
a per-method level. Optimistic Concurrency Control is introduced
with this feature and utilizes a low backend locking and
over-qualified updates. The new Concurrency Control and
Isolation Level settings are fully configurable using AAT
version 27 or later.

It should be noted that because of the new function provided
by PQ55873 and the fixes for the following defects, your
installation may experience an improvment in performance from
certain workloads.

(MD11251) Snoozer code has been restructured to eliminate some
timing windows that can cause references to deleted objects.

(MD13100) A new environment variable, MAX_SRS, is created to
provide an interface to the WLM IWMSLIM service for the SR.
This mirrors the already existing MIN_SRS environment variable.

(
PQ52868) Support is provided to allow CMP entity beans to
share DB2 connections.

(
PQ53749) Support is provided to allow DB2 connections (other
than container-managed connections for CMP beans) to be reused
within the scope of a single global transaction. In conjunction
with this, a JVM property,
com.ibm.ws390.ConnectionUsageScopeDefault, is provided to allow
an installation to indicate whether or not DB2 connections are
to be reused. This option is not applicable to DB2 connections
obtained by the container for CMP beans. The container does its
own connection reuse management of CMP beans.

(
PQ56914) Classloading design when reading and writing EAR files
has been modified to handle the case where sibling classloaders
for contained Zip/Jar require reference delegation. Note that
this classloader change will NOT affect the runtime classloading
behavior. This deployment classloader functionality will not
prevent a potential NoClassDefFoundError during runtime
regardless of which classloading (visibility) mode is being
used during runtime, because it is separate from runtime
classloader behavior.

For information about Connectors support and Concurrency Control
Management support provided in this APAR, two separate documents
are provided:
*  WebSphere Application Server V4.0.1 for z/OS and
   OS/390:  WebSphere for z/OS-supported Connectors

*  WebSphere Application Server V4.0.1 for z/OS and
   OS/390:  Concurrency Control Management

To download these documents, go to the following Web
site, then click "Product information."


http://www.ibm.com/software/webservers/appserv/zos_os390/
support.html

At a later time, the information in these documents will be
integrated into the WebSphere for z/OS formal
publications.  To access the latest publications, go to
the product library page at:


http://www.ibm.com/software/webservers/appserv/

The following publication was revised as a result of this APAR:
________________________________________________________________
WebSphere Application Server V4.0.1 for z/OS and OS/390
Messages and Diagnosis: GA22-7837-02
________________________________________________________________
NOTE: Periodically, we refresh the documentation on our
Web site, so the changes might have been made before you
read this text. To access the latest online
documentation, go to the product library page at:


http://www.ibm.com/software/webservers/appserv/
________________________________________________________________
Chapter 13, pg. 348 (deleted)
C9C21046
Explanation: IBM Internal Only
User Response: Contact the IBM Support Center
________________________________________________________________
________________________________________________________________
Document Name: WebSphere Application Server V4.0.1 for
               z/OS and OS/390: Installation and
               Customization - Document Number: GA22-7834-03
________________________________________________________________
In "Appendix A, Environment variables," on page 323, add
the following row to Table 42:
+---------------------------+-------------+-------------+
| ENVIRONMENT VARIABLE =    | ...         | BUSINESS    |
| <DEFAULT>                 |             | APPLICATION |
|                           |             | SERVER      |
+---------------------------+-------------+-------------+
| MAX_SRS=0                 |             | O           |
+---------------------------+-------------+-------------+
On page 340, add the following environment variable description:

MAX_SRS=NN
    Specifies the total number of server regions allowed
    by Workload Management to run concurrently in the
    server's application environment; that is, Workload
    Management will not start more server regions for a
    particular application environment than are specified
    through this environment variable.

    Use this environment variable to limit the number of
    server regions created by Workload Management for a
    server.  The default is zero, which means there is no
    limit.
    EXAMPLE:   MAX_SRS=10

APAR PQ55873 is associated with SERVICE LEVEL W401030 of
WebSphere Application Server V4.0.1 for z/OS and OS/390.
Temporary fix Comments
APAR information
APAR number PQ55873
Reported component name WASKBASE
Reported component ID 5655A9801
Reported release 401
Status CLOSED PER
PE NoPE
HIPER NoHIPER
Submitted date 2001-12-13
Closed date 2002-03-13
Last modified date 2002-04-02

APAR is sysrouted FROM one or more of the following:

APAR is sysrouted TO one or more of the following:
UQ99329

Modules/Macros
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BBOAXIAI BBOBOA BBOCASYD BBOCASYH BBOCASYN BBOCASYS
BBOCEIOP BBOCENCP BBOCHSES BBOCLSES BBOCLSHS BBOCLSPC
BBOCPOCB BBOCSESS BBOCSHSB BBOCSMGR BBOCSMRH BBOCSMRI
BBOCSMRL BBOCSMRS BBOCSSES BBOCSSHS BBOCWBAL BBODADT
BBODASRP BBODASRR BBODASRS BBODASRU BBODDAUT BBODENFL
BBODMN BBODRDTA BBOFAPPS BBOFDBC BBOFDBM BBOFDKB
BBOFRAS BBOIAPPS BBOIBTO BBOIBYTE BBOIDRMI BBOIGTID
BBOIHCOI BBOIHDOI BBOIIMAI BBOIIMCI BBOIIMLI BBOIIMSI
BBOIKEYS BBOILEI BBOILOCK BBOILPCI BBOILPI BBOILSEI
BBOILSMI BBOIMACI BBOIMCOI BBOIMOI BBOIMORI BBOIRDBI
BBOIROOT BBOIRSCN BBOISOI BBOISTOR BBOITMLI BBOI3MQI
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BBOLPOI BBOLRAS BBOLRT BBOLRTU BBOLSHCP BBOLSREQ
BBOLSS BBOLSYS BBOLUTIL BBOMAPPS BBOMBOOT BBOMCDM
BBOMDDLC BBOMDDLI BBOMDDLO BBOMDDLR BBOMDDLT BBOMDDLV
BBOMDDLX BBOMDDLZ BBOMENV BBOMEXIM BBOMGADM BBOMHFSM
BBOMIBO BBOMIB02 BBOMIB04 BBOMIB06 BBOMIB10 BBOMIB15
BBOMIB19 BBOMIB23 BBOMIB27 BBOMIB33 BBOMIB37 BBOMIB41
BBOMIB45 BBOMIB48 BBOMIB58 BBOMIB62 BBOMIB64 BBOMIB66
BBOMIB68 BBOMIB70 BBOMIB80 BBOMIB81 BBOMIB82 BBOMIB83
BBOMIB84 BBOMIB85 BBOMIB86 BBOMICPI BBOMID02 BBOMID04
BBOMID06 BBOMID10 BBOMID15 BBOMID19 BBOMID23 BBOMID27
BBOMID33 BBOMID37 BBOMID41 BBOMID45 BBOMID48 BBOMID58
BBOMID62 BBOMID64 BBOMID66 BBOMID68 BBOMID70 BBOMID80
BBOMID81 BBOMID82 BBOMID83 BBOMID84 BBOMID85 BBOMID86
BBOMIEVA BBOMIEXC BBOMIMRI BBOMIM10 BBOMIOR BBOMPDB2
BBOMPROC BBOMRDI BBOMREQI BBOMSBO BBOMSBOI BBOMSBOS
BBOMSBO1 BBOMSBO2 BBOMSBO3 BBOMSBO4 BBOMSBO5 BBOMSBO6
BBOMSBO7 BBOMSBO8 BBOMSCCO BBOMSCCR BBOMSCCS BBOMSCDA
BBOMSCDL BBOMSCHE BBOMSCHI BBOMSCJ2 BBOMSCLC BBOMSCMD
BBOMSCME BBOMSCMO BBOMSCMT BBOMSCO BBOMSCPI BBOMSCPR
BBOMSCRS BBOMSCSR BBOMSCTA BBOMSD51 BBOMSD52 BBOMSD90
BBOMSMOI BBOMSMOS BBOMSMS BBOMSVSA BBOMSXML BBOMSYSI
BBOMUTIL BBOOACRT BBOOAC ***This field was
truncated. To obtain the full apar
record, please contact your local support
center.***          

Fix information
Fixed component name WASKBASE
Fixed component ID 5655A9801

Applicable component levels
R401 PSY UQ99329    UP02/03/21 P F203

  Fix is available
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Document Information


Product categories: Software > Application Servers > Distributed Application & Web Servers > WebSphere Application Server for z/OS
Operating system(s):
Software version: 401
Software edition:
Reference #: PQ55873
IBM Group: Software Group
Modified date: Apr 2, 2002