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  • Reading HTML table data / html tag

    - by user348038
    I have some 50 pages of html which have around 100-plus rows of data in each, with all sort of CSS style, I want to read the html file and just get the data, like Name, Age, Class, Teacher. and store it in Database, but I am not able to read the html tags e.g space i kept to display it here <table class="table_100"> <tr> <td class="col_1"> <span class="txt_student">Gauri Singh</span><br> <span class="txt_bold">13</span><br> <span class="txt_bold">VIII</span><br> </td> <td class="col_2"> <span class="txt_teacher">Praveen M</span><br> <span class="txt_bold">3494</span><br> <span class="txt_bold">3Star</span><br> </td> <td class="col_3"> </td> </tr> </table>

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  • Not getting the right expected output for my Mysql Query?

    - by user1878107
    i've 4 tables as shown below doctors id name ------------ 1 Mathew 2 Praveen 3 Rosie 4 Arjun 5 Denis doctors_appointments id doctors_id patient_name contact date status -------------------------------------------------------------------------------------- 1 5 Nidhin 9876543210 2012-12-10 15:39:41 Registered 2 5 Sunny 9876543210 2012-12-18 15:39:48 Registered 3 5 Mani 9876543210 2012-12-12 15:39:57 Registered 4 2 John 9876543210 2012-12-24 15:40:09 Registered 5 4 Raj 9876543210 2012-12-05 15:41:57 Registered 6 3 Samuel 9876543210 2012-12-14 15:41:33 Registered 7 2 Louis 9876543210 2012-12-24 15:40:23 Registered 8 1 Federick 9876543210 2012-12-28 15:41:05 Registered 9 2 Sam 9876543210 2012-12-12 15:40:38 Registered 10 4 Sita 9876543210 2012-12-12 15:41:00 Registered doctors_dutyplan id doctor_id weeks time no_of_patients ------------------------------------------------------------------ 1 1 3,6,7 9:00am-1:00pm 10 2 2 3,4,5 1:00pm-4:00pm 7 3 3 3,6,7 10:00am-2:00pm 10 4 4 3,4,5,6 8:30am-12:30pm 12 5 5 3,4,5,6,7 9:00am-4:00pm 30 emp_leave id empid leavedate -------------------------------- 1 2 2012-12-05 14:42:36 2 2 2012-12-03 14:42:59 3 3 2012-12-03 14:43:06 4 3 2012-12-06 14:43:14 5 5 2012-12-04 14:43:24 My task is to find all the days in a month in which the doctor is available excluding the leave dates. My query what is wrote is given below: SELECT DATE_ADD( '2012-12-01', INTERVAL ROW DAY ) AS Date, ROW +1 AS DayOfMonth FROM ( SELECT @row := @row +1 AS ROW FROM ( SELECT 0 UNION ALL SELECT 1 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 )t1, ( SELECT 0 UNION ALL SELECT 1 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 )t2, ( SELECT @row := -1 )t3 LIMIT 31 )b WHERE DATE_ADD( '2012-12-01', INTERVAL ROW DAY ) BETWEEN '2012-12-01' AND '2012-12-31' AND DAYOFWEEK( DATE_ADD( '2012-12-01', INTERVAL ROW DAY ) ) =2 AND DATE_ADD( '2012-12-01', INTERVAL ROW DAY ) NOT IN ( SELECT DATE_FORMAT( l.leavedate, '%Y-%m-%d' ) AS date FROM doctors_dutyplan d LEFT JOIN emp_leave AS l ON d.doctor_id = l.empid WHERE doctor_id =2 ) This works fine for all doctors who took any leave in a particular day in a month (here in the example it is Decemeber 2012). and the result is shown below: Date DayOfMonth ----------------------- 2012-12-10 10 2012-12-17 17 2012-12-24 24 2012-12-31 31 But on the other hand for the doctors who did'nt took any leave , for that my query is showing empty table, example for the doctor Mathew whose id is 1, my query returns an empty result can anyone please tell a solution for this problem. Thanks in advance.

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  • Workshops, online content show how Oracle infuses simplicity, mobility, extensibility into user experience

    - by mvaughan
    By Kathy Miedema & Misha Vaughan, Oracle Applications User Experience Oracle has made a huge investment into the user experience of its many different software product families, and recent releases showcase big changes and features that aim to promote end user engagement and efficiency by streamlining navigation and simplifying the user interface. But making Oracle’s enterprise software great-looking and usable doesn’t stop when Oracle products go out the door. The Applications User Experience (UX) team recognizes that our customers may need to customize software to fit their work processes. And that’s why we provide tools such as user experience design patterns to help you maintain the Oracle user experience as you tailor your application to fit your business needs. Often, however, customers may need some context around user experience. How has the Oracle user experience been designed and constructed? Why is a good user experience important for users? How does understanding what goes into the user experience benefit the people who purchase the software for users? There’s a short answer to these questions, and you can read about it on Usable Apps. But truly understanding Oracle’s investment and seeing how it applies across product families occasionally requires a deeper dive into the Oracle user experience, especially if you’re an influencer or decision-maker about Oracle products. To help frame these decisions, the Communications & Outreach team has developed several targeted workshops that explore what Oracle means when it talks about user experience, and provides a roadmap into where the Oracle user experience is going. These workshops require non-disclosure agreements, and have been delivered to Oracle sales folks, Oracle partners, Oracle ACE Directors and ACEs, and a few customers. Some of these audience members have been developers or have a technical background; just as many did not. Here’s a breakdown of the kind of training you can get around the Oracle user experience from the OAUX Communications & Outreach team.For Partners: George Papazzian, Principal, Naviscent with Joyce Ohgi, Oracle Oracle Fusion Applications HCM Pre-Sales Seminar:  In concert with Worldwide Alliances  and  Channels under Applications Partner Enablement Director Jonathan Vinoskey’s guidance, the Applications User Experience team delivers a two-day workshop.  Day one focuses on Oracle Fusion Applications HCM and pre-sales strategy, and Day two focuses on positioning and leveraging Oracle’s investment in the Oracle Fusion Applications user experience.  The next workshops will occur on the following dates: December 4-5, 2013 @ Manchester, UK January 29-30, 2014 @ Reston, Virginia February 2014 @ Guadalajara, Mexico (email: Shannon Whiteman) March 11-12, 2014 @ Dubai, United Arab Emirates April 1-2, 2014 @ Chicago, Illinois Partner Advisory Board: A two-day board meeting in the U.S. and U.K. to discuss four main user experience areas for Oracle Fusion Applications: simplicity, visualization & analytics, mobility, & futures. This event is limited to Oracle Diamond Partners, UX bloggers, and key UX influencers and requires legal documentation.  We will be talking about the Oracle applications UX strategy and roadmap. Partner Implementation Training on User Interface: How to Build Great-Looking, Usable Apps:  In this two-day, hands-on workshop built around Oracle’s Application Development Framework, learn how to build desktop and mobile user interfaces and mobile user interfaces based on Oracle’s experience with Fusion Applications. This workshop is for partners with a technology background who are looking for ways to tailor Fusion Applications using ADF, or have built their own custom solutions using ADF. It includes an introduction to UX design patterns and provides tools to build usability-tested UX designs. Nov 5-6, 2013 @ Redwood Shores, CA, USA January 28-29th, 2014 @ Reston, Virginia, USA February 25-26, 2014 @ Guadalajara, Mexico March 9-10, 2014 @ Dubai, United Arab Emirates To register, contact [email protected] Simplified UI Customization & Extensibility:  Pilot workshop:  We will be reviewing the proposed content for communicating the user experience tool kit available with the next release of Oracle Fusion Applications.  Our core focus will be on what toolkit components our system implementors and independent software vendors will need to respond to customer demand, whether they are extending Fusion Applications, or building custom applications, that will need to leverage the simplified UI. Dec 11th, 2013 @ Reading, UK For information: contact [email protected] Private lab tour and demos: Interested in seeing what’s going on in the Apps UX Labs?  If you are headed to the San Francisco Bay Area, let us know. We can arrange a spin through our usability labs at headquarters. OAUX Expo: This open-house forum gives partners a look at what the UX team is working on, and showcases the next-generation user experiences in a demo environment where attendees can see and touch the applications. UX Direct: Use the same methods that Oracle uses to develop its own user experiences. We help you define your users and their needs, and then provide direction on how to tailor the best user experience you can for them. For CustomersAngela Johnston, Gozel Aamoth, Teena Singh, and Yen Chan, Oracle Lab tours: See demos of soon-to-be-released products, and take a spin on usability research equipment such as our eye-tracker. Watch this video to get an idea of what you’ll see. Get our newsletter: Learn about newly released products and see where you can meet us at user group conferences. Participate in a feedback session: Join a focus group or customer feedback session to get an early look at user experience designs for the next generation of software, and provide your thoughts on how well it will work. Join the OUAB: The Oracle Usability Advisory Board meets several times a year to discuss trends in the workforce and provide direction on user experience designs. UX Direct: Use the same methods that Oracle uses to develop its own user experiences. We help you define your users and their needs, and then provide direction on how to tailor the best user experience you can for them. For Developers (customers, partners, and consultants): Plinio Arbizu, SP Solutions, Richard Bingham, Oracle, Balaji Kamepalli, EiSTechnoogies, Praveen Pillalamarri, EiSTechnologies How to Build Great-Looking, Usable Apps: This workshop is for attendees with a strong technology background who are looking for ways to tailor customer software using ADF. It includes an introduction to UX design patterns and provides tools to build usability-tested UX designs.  See above for dates and times. UX design patterns web site: Cut the length of your project down by months. Use these patterns to build out the task flow you need to develop for your users. The patterns have already been usability-tested and represent the best practices that the Oracle UX research team has found in its studies. UX Direct: Use the same methods that Oracle uses to develop its own user experiences. We help you define your users and their needs, and then provide direction on how to tailor the best user experience you can for them. For Oracle Sales Mike Klein, Jeremy Ashley, Brent White, Oracle Contact your local sales person for more information about the Oracle user experience and the training available from the Applications User Experience Communications & Outreach team. See customer-friendly user experience collateral ranging from the new simplified UI in Oracle Fusion Applications Release 7, to E-Business Suite user experience highlights, to Siebel, PeopleSoft, and JD Edwards user experience highlights.   Receive access to the same pre-sales and implementation training we provide to partners. For Oracle Sales only: Oracle-only training on the Oracle Fusion Applications UX Innovation Sales Kit.

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  • Random Access Violation Exception in WPF Application

    - by PT1984
    Hi, I am facing weird problem while running regression tests on my WPF Application. I am getting AccessViolationException with different stacktraces each time. First : Message :Attempted to read or write protected memory. This is often an indication that other memory is corrupt. StackTrace : at MS.Win32.PresentationCore.UnsafeNativeMethods.MILUnknown.Release(IntPtr pIUnkown) at MS.Win32.PresentationCore.UnsafeNativeMethods.MILUnknown.ReleaseInterface(IntPtr& ptr) at System.Windows.Media.SafeMILHandle.ReleaseHandle() at System.Runtime.InteropServices.SafeHandle.InternalFinalize() at System.Runtime.InteropServices.SafeHandle.Dispose(Boolean disposing) at System.Runtime.InteropServices.SafeHandle.Finalize() Source :PresentationCore Type : System.AccessViolationException. Second : Message :Attempted to read or write protected memory. This is often an indication that other memory is corrupt. StackTrace : at MS.Win32.PresentationCore.UnsafeNativeMethods.IMILBitmapEffect.GetOutput(SafeHandle THIS_PTR, UInt32 uiIndex, SafeMILHandle pContext, BitmapSourceSafeMILHandle& ppBitmapSource) at System.Windows.Media.Effects.BitmapEffect.GetOutput(SafeHandle unmanagedEffect, Int32 index, BitmapEffectRenderContext context) at System.Windows.Media.Effects.BitmapEffect.GetOutput(BitmapEffectInput input) at System.Windows.Media.Effects.BitmapEffectState.GetEffectOutput(Visual visual, RenderTargetBitmap& renderBitmap, Matrix worldTransform, Rect windowClip, Matrix& finalTransform) at System.Windows.Media.Effects.BitmapEffectVisualState.RenderBitmapEffect(Visual visual, Channel channel) at System.Windows.Media.Effects.BitmapEffectContent.ExecuteRealizationsUpdate() at System.Windows.Media.RealizationContext.RealizationUpdateSchedule.Execute() at System.Windows.Media.MediaContext.Render(ICompositionTarget resizedCompositionTarget) at System.Windows.Media.MediaContext.RenderMessageHandlerCore(Object resizedCompositionTarget) at System.Windows.Media.MediaContext.AnimatedRenderMessageHandler(Object resizedCompositionTarget) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter) at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) at System.Windows.Threading.Dispatcher.WrappedInvoke(Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) at System.Windows.Threading.DispatcherOperation.InvokeImpl() at System.Windows.Threading.DispatcherOperation.InvokeInSecurityContext(Object state) at System.Threading.ExecutionContext.runTryCode(Object userData) at System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData) at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Windows.Threading.DispatcherOperation.Invoke() at System.Windows.Threading.Dispatcher.ProcessQueue() at System.Windows.Threading.Dispatcher.WndProcHook(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter) at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) at System.Windows.Threading.Dispatcher.WrappedInvoke(Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler) at System.Windows.Threading.Dispatcher.InvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Boolean isSingleParameter) at System.Windows.Threading.Dispatcher.Invoke(DispatcherPriority priority, Delegate method, Object arg) at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam) at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg) at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame) at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame) at System.Windows.Threading.Dispatcher.Run() at System.Windows.Application.RunDispatcher(Object ignore) at System.Windows.Application.RunInternal(Window window) at System.Windows.Application.Run(Window window) at System.Windows.Application.Run() at Main() Source :PresentationCore Type :System.AccessViolationException In Application Event Log I found following entries : Dispatcher processing has been suspended, but messages are still being processed. Faulting application **.exe, version 1.0.0.*, stamp 4c08d288, faulting module wpfgfx_v0300.dll, version 3.0.6920.1427, stamp 488f3056, debug? 0, fault address 0x0012ec36. My Application uses Dispatcher from another thread, to change the values of the controls , enable - disable those, change visibility etc., the thred is run multiple times in a second. Please let me know if anybody has faced this problem? Thanks in advance, -Prasad

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  • Recreating OMS instances in a HA environment when instances on all nodes are lost

    - by rnigam
    Oracle highly recommends deploying EM in a HA environment. The best practices for HA deployments, backup and housekeeping of your Enterprise Manager environment are documented in the Oracle Enterprise Manager Advanced Configuration Guide. It is imperative that there is a good disaster recovery plan in place for your EM deployment. In this post I want to talk about a customer who failed to do the correct planning and housekeeping for EM and landed in a situation where we the all the OMSes were nearly blown away had we not jumped to help. We recently hit an issue at a customer site where we had a two node OMS setup of the Enterprise Manager and a RAC Database being used as the EM repository. An accidental delete of the OMS oracle home left us with a single node deployment. While we were trying to figure out a possible path to recover the first node, the second node was rebooted under a maintenance window. What followed was a complete site outage as the Admin and managed servers would not start on either of the nodes. In my situation there were - No backups of the Oracle Homes from any node - No OMS Configuration snapshots (created using the “emctl exportconfig oms” command) and the instance home was completely lost on node 1 which also had the Admin Server  We did however have: - A copy of the emkey.ora that I found under the OMS_ORACLE_HOME/ of the second node (NOTE: it is a bad practice to have your emkey present under the OMS Oracle home directory on the same server as the OMS. The backup of the emkey should be maintained on some other server. In this case however it was a savior in my situation since there were no backups - The oms oracle home on the second node but missing a number of files and had a number of changes done to the files in the home. There were a number of attempts to start the server by modifying various files based on the Weblogic server logs to have atleast node up and running but all of them failed. Here is how you can recover from this scenario: Follow these steps: STEP 1: Check status of emkey.ora Check whether the emkey exists is present in the EM repository or not. Run the following command: $OMS_ORACLE_HOME/bin/emctl status emkey If the output is something like this below then you are good to go and the key is present in the repository ./emctl status emkey Oracle Enterprise Manager 11g Release 1 Grid Control Copyright (c) 1996, 2010 Oracle Corporation. All rights reserved. Enter Enterprise Manager Root (SYSMAN) Password : The EMKey is configured properly. Here are the messages that you might see as the emctl status emkey output depending upon whether the EM Admin Server is up and if the key is configured properly: Case1:  AdminServer is up, emkey is proper in CredStore & not in repos. This is same as the output of the command shown above:The EMKey is configured properly Case 2: AdminServer is up, emkey is proper in CredStore & exists in repos:The EMKey is configured properly, but is not secure. Secure the EMKey by running "emctl config emkey -remove_from_repos".Case 3: AdminServer is down or emkey is corrupted in CredStore) & (emkey exists in repos): The EMKey exists in the Management Repository, but is not configured properly or is corrupted in the credential store.Configure the EMKey by running "emctl config emkey -copy_to_credstore".Case 4: (AdminServer is down or emkey is corrupted in CredStore) & (emkey does not exist in repos): The EMKey is not configured properly or is corrupted in the credential store and does not exist in the Management Repository. To correct the problem:1) Get the backed up emkey.ora file.2) Configure the emkey by running "emctl config emkey -copy_to_credstore_from_file". If not the key was not secured properly, we will have to be put in the repository before proceeding. Look at the next step 2 for doing this There may be cases (like mine) where running emctl may give errors like the following: $OMS_ORACLE_HOME/bin/emctl status emkey Exception in thread “Main Thread” java.lang.NoClassDefFoundError: oracle/security/pki/OracleWallet At oracle.sysman.emctl.config.oms.EMKeyCmds.main (EMKeyCmds.java:658) Just move to the next step to put the key back in the repository STEP 2: Put emkey.ora back in the repository Skip this step if your emkey.ora is present in the repository. If not, you need to put the key back in the repository See if you can run the following command (with sample output): $OMS_ORACLE_HOME/bin/emctl config emkey –copy_to_repos Oracle Enterprise Manager 11g Release 1 Grid Control Copyright (c) 1996, 2010 Oracle Corporation. All rights reserved. The EMKey has been copied to the Management Repository. This operation will cause the EMKey to become unsecure. After the required operation has been completed, secure the EMKey by running "emctl config emkey -remove_from_repos". Typically the key is present under $OMS_ORACLE_HOME/sysman/config directory before being removed after the install as a best practice. If you hit any errors while running emctl commands like the one mentioned in step 1, jump to step 3 and we will take care of the emkey.ora in Step 5 STEP 3: Get the port information Check for the existing port information in the emd.properties file under EM_INSTANCE_DIRECTORY (typically gc_inst directory right above the Middleware home where you have deployed em. For eg. /u01/app/oracle/product/gc_inst in case your oms home is /u01/app/oracle/product/Middleware/oms11g) In my case I got the information from the emgc.properties present in the gc_inst on the second node. If you can run emctl you may want to try the following command as well $OMS_ORACLE_HOME/bin/emctl status oms –details Note this information as this will be used in the next step STEP 4: Perform cleanup on Node 1 Note the oracle home of the Weblogic and OMS, get the list of applied patches in the homes (using opatch lsinventory command), take a backup copy of the home just in case we need it and then de-install/remove oracle homes, update inventory and cleanup processes on the first node STEP 5: Perform Software Only Installation of OMS on Node 1 Perform Weblogic 10.3.2 installation exactly under the same location as present in the earlier installation. Perform software only installation of the OMS using the following command. This will not run any configuration assistants and bypass all user interface validations runInstaller –noconfig -validationaswarnings Select the “Additional OMS” option while performing the installation. Provide the same path for OMS and Instance directories like the previous installation Use the port information collected in Step 3 while performing the installation. Once the installation is complete run the allroot.sh script to complete the binary deployment STEP 6: Apply one-off patches At this point you can apply any patches to the OMS Oracle Home previously. You only need to run opatch to install the patch in the home and not required to run the SQLs STEP 7: Copy EM key This step is only required if you were not able to use emctl command to put the emkey back into the EM repository in STEP 2 Copy the emkey.ora file of the old installation you have under $OMS_ORACLE_HOME/sysman/config directory of the newly installed OMS STEP 8: Configure Grid Control Domain Run the following command to configure the EM domain and OMS. Note that you need to use a different GC Domain name than what you used earlier. For example I have used GCDOMAIN11 as the new domain name when my previous domain name was GCDOMAIN $OMS_ORACLE_HOME/bin/omsca new –AS_USERNAME weblogic –EM_DOMAIN_NAME GCDOMAIN11 –NM_USER nodemanager -nostart This command as shown below will prompt for a number of inputs like Admin Server hostname, port, password, etc. Verify if the defaults shown are correct by pressing enter or provide a new value STEP 9: Run Add-ON Configuration Assistant After this step run the following add-on configuration assistant. This was used in my case to configure the virtualization add-on $OMS_ORACLE_HOME/addonca -oui -omsonly -name vt -install gc STEP 10: Start the OMS Now start the OMS using $OMS_ORACLE_HOME/bin/emctl start oms In a multi-node setup like mine you would either have a software load balancer or DNS round robin (using a virtual host name that resolves to one of multiple OMS hostnames) being used for load balancing. Secure the OMS against the SLB or DNS virtual hostname using the following $ OMS_HOME/bin/emctl secure oms -host slb.example.com -secure_port 1159 -slb_port 1159 -slb_console_port 443 STEP 11: Configure the Agent From the $AGENT_ORACLE_HOME/bin run the ./agentca –f At this point you should have your OMS on node 1 fully re-covered. Clean up node 2 and use the normal Additional OMS installation process documented in the official installation guide to add the additional OMS on node 2 Summary It took us nearly a little over two days to completely recover the environment with some other non-EM related issues that hit us along the way as well. In the end a situation like this could have been completely avoided had the proper housekeeping and backup of the Enterprise Manager Deployment been done in the first place. This is going to a topic that we cover in the next post. In the meantime please do refer to the Oracle Enterprise Manager Advanced Configuration Guide for planning your EM installation, backup and housekeeping procedures. This can be found here: http://download.oracle.com/docs/cd/E11857_01/index.htm Thanks This post would not have been possible without Raj Aggarwal, Prasad Chebrolu and Ravikumar Basa who helped to recover the environment and provided all the support we needed

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  • Following the Thread in OSB

    - by Antony Reynolds
    Threading in OSB The Scenario I recently led an OSB POC where we needed to get high throughput from an OSB pipeline that had the following logic: 1. Receive Request 2. Send Request to External System 3. If Response has a particular value   3.1 Modify Request   3.2 Resend Request to External System 4. Send Response back to Requestor All looks very straightforward and no nasty wrinkles along the way.  The flow was implemented in OSB as follows (see diagram for more details): Proxy Service to Receive Request and Send Response Request Pipeline   Copies Original Request for use in step 3 Route Node   Sends Request to External System exposed as a Business Service Response Pipeline   Checks Response to Check If Request Needs to Be Resubmitted Modify Request Callout to External System (same Business Service as Route Node) The Proxy and the Business Service were each assigned their own Work Manager, effectively giving each of them their own thread pool. The Surprise Imagine our surprise when, on stressing the system we saw it lock up, with large numbers of blocked threads.  The reason for the lock up is due to some subtleties in the OSB thread model which is the topic of this post.   Basic Thread Model OSB goes to great lengths to avoid holding on to threads.  Lets start by looking at how how OSB deals with a simple request/response routing to a business service in a route node. Most Business Services are implemented by OSB in two parts.  The first part uses the request thread to send the request to the target.  In the diagram this is represented by the thread T1.  After sending the request to the target (the Business Service in our diagram) the request thread is released back to whatever pool it came from.  A multiplexor (muxer) is used to wait for the response.  When the response is received the muxer hands off the response to a new thread that is used to execute the response pipeline, this is represented in the diagram by T2. OSB allows you to assign different Work Managers and hence different thread pools to each Proxy Service and Business Service.  In out example we have the “Proxy Service Work Manager” assigned to the Proxy Service and the “Business Service Work Manager” assigned to the Business Service.  Note that the Business Service Work Manager is only used to assign the thread to process the response, it is never used to process the request. This architecture means that while waiting for a response from a business service there are no threads in use, which makes for better scalability in terms of thread usage. First Wrinkle Note that if the Proxy and the Business Service both use the same Work Manager then there is potential for starvation.  For example: Request Pipeline makes a blocking callout, say to perform a database read. Business Service response tries to allocate a thread from thread pool but all threads are blocked in the database read. New requests arrive and contend with responses arriving for the available threads. Similar problems can occur if the response pipeline blocks for some reason, maybe a database update for example. Solution The solution to this is to make sure that the Proxy and Business Service use different Work Managers so that they do not contend with each other for threads. Do Nothing Route Thread Model So what happens if there is no route node?  In this case OSB just echoes the Request message as a Response message, but what happens to the threads?  OSB still uses a separate thread for the response, but in this case the Work Manager used is the Default Work Manager. So this is really a special case of the Basic Thread Model discussed above, except that the response pipeline will always execute on the Default Work Manager.   Proxy Chaining Thread Model So what happens when the route node is actually calling a Proxy Service rather than a Business Service, does the second Proxy Service use its own Thread or does it re-use the thread of the original Request Pipeline? Well as you can see from the diagram when a route node calls another proxy service then the original Work Manager is used for both request pipelines.  Similarly the response pipeline uses the Work Manager associated with the ultimate Business Service invoked via a Route Node.  This actually fits in with the earlier description I gave about Business Services and by extension Route Nodes they “… uses the request thread to send the request to the target”. Call Out Threading Model So what happens when you make a Service Callout to a Business Service from within a pipeline.  The documentation says that “The pipeline processor will block the thread until the response arrives asynchronously” when using a Service Callout.  What this means is that the target Business Service is called using the pipeline thread but the response is also handled by the pipeline thread.  This implies that the pipeline thread blocks waiting for a response.  It is the handling of this response that behaves in an unexpected way. When a Business Service is called via a Service Callout, the calling thread is suspended after sending the request, but unlike the Route Node case the thread is not released, it waits for the response.  The muxer uses the Business Service Work Manager to allocate a thread to process the response, but in this case processing the response means getting the response and notifying the blocked pipeline thread that the response is available.  The original pipeline thread can then continue to process the response. Second Wrinkle This leads to an unfortunate wrinkle.  If the Business Service is using the same Work Manager as the Pipeline then it is possible for starvation or a deadlock to occur.  The scenario is as follows: Pipeline makes a Callout and the thread is suspended but still allocated Multiple Pipeline instances using the same Work Manager are in this state (common for a system under load) Response comes back but all Work Manager threads are allocated to blocked pipelines. Response cannot be processed and so pipeline threads never unblock – deadlock! Solution The solution to this is to make sure that any Business Services used by a Callout in a pipeline use a different Work Manager to the pipeline itself. The Solution to My Problem Looking back at my original workflow we see that the same Business Service is called twice, once in a Routing Node and once in a Response Pipeline Callout.  This was what was causing my problem because the response pipeline was using the Business Service Work Manager, but the Service Callout wanted to use the same Work Manager to handle the responses and so eventually my Response Pipeline hogged all the available threads so no responses could be processed. The solution was to create a second Business Service pointing to the same location as the original Business Service, the only difference was to assign a different Work Manager to this Business Service.  This ensured that when the Service Callout completed there were always threads available to process the response because the response processing from the Service Callout had its own dedicated Work Manager. Summary Request Pipeline Executes on Proxy Work Manager (WM) Thread so limited by setting of that WM.  If no WM specified then uses WLS default WM. Route Node Request sent using Proxy WM Thread Proxy WM Thread is released before getting response Muxer is used to handle response Muxer hands off response to Business Service (BS) WM Response Pipeline Executes on Routed Business Service WM Thread so limited by setting of that WM.  If no WM specified then uses WLS default WM. No Route Node (Echo functionality) Proxy WM thread released New thread from the default WM used for response pipeline Service Callout Request sent using proxy pipeline thread Proxy thread is suspended (not released) until the response comes back Notification of response handled by BS WM thread so limited by setting of that WM.  If no WM specified then uses WLS default WM. Note this is a very short lived use of the thread After notification by callout BS WM thread that thread is released and execution continues on the original pipeline thread. Route/Callout to Proxy Service Request Pipeline of callee executes on requestor thread Response Pipeline of caller executes on response thread of requested proxy Throttling Request message may be queued if limit reached. Requesting thread is released (route node) or suspended (callout) So what this means is that you may get deadlocks caused by thread starvation if you use the same thread pool for the business service in a route node and the business service in a callout from the response pipeline because the callout will need a notification thread from the same thread pool as the response pipeline.  This was the problem we were having. You get a similar problem if you use the same work manager for the proxy request pipeline and a business service callout from that request pipeline. It also means you may want to have different work managers for the proxy and business service in the route node. Basically you need to think carefully about how threading impacts your proxy services. References Thanks to Jay Kasi, Gerald Nunn and Deb Ayers for helping to explain this to me.  Any errors are my own and not theirs.  Also thanks to my colleagues Milind Pandit and Prasad Bopardikar who travelled this road with me. OSB Thread Model Great Blog Post on Thread Usage in OSB

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