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  • Parallel.For(): Update variable outside of loop

    - by TSS
    I'm just looking in to the new .NET 4.0 features. With that, I'm attempting a simple calculation using Parallel.For and a normal for(x;x;x) loop. However, I'm getting different results about 50% of the time. long sum = 0; Parallel.For(1, 10000, y => { sum += y; } ); Console.WriteLine(sum.ToString()); sum = 0; for (int y = 1; y < 10000; y++) { sum += y; } Console.WriteLine(sum.ToString()); My guess is that the threads are trying to update "sum" at the same time. Is there an obvious way around it?

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  • Generating data on unlevel background

    - by bluejay93
    I want to make an unlevel background and then generate some test data on that using Matlab. I was not clear when I asked this question earlier. So for this simple example for i = 1:10 for j = 1:10 f(i,j)=X.^2 + Y.^2 end end where X and Y have been already defined, it plots it on a flat surface. I don't want to distort the function itself, but I want the surface that it goes onto to be unlevel, changed by some degree or something. I hope that's a little clearer.

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  • Parallelizing for loop

    - by vman049
    I have MATLAB code which I'm trying to parallelize with a simple change from "for" to "parfor." I'm unable to do so because of an error I'm receiving on the variable "votes" which states: Valid indices for 'votes' are restricted in PARFOR loops. Explanation: For MATLAB to execute parfor loops efficiently, the amount of data sent to the MATLAB workers must be minimal. One of the ways MATLAB achieves this is by restricting the way variables can be indexed in parfor iterations. The indicated variable is indexed in a way that is incompatible with parfor. Suggested Action: Fix the indexing. For a description of the indexing restrictions, see “Sliced Variables” in the Parallel Computing Toolbox documentation. Below is my code: votes = zeros(num_layers, size(spikes, 1), size(SVMs_layer1, 1)); predDir = zeros(size(spikes, 1), 1); chronProb = zeros([num_layers, size(chronDists)]); for i = 1:num_layers switch i case 1 B = B1; k_elem_temp = k_elem1; rest_elem_temp = rest_elem1; case 2 B = B2; k_elem_temp = k_elem2; rest_elem_temp = rest_elem2; case 3 B = B3; k_elem_temp = k_elem3; rest_elem_temp = rest_elem3; end for j = 1:length(chronPred) if chronDists(i, j, :) ~= 0 parfor k = 1:8 chronProb(i, j, k) = logistic(B{k}(1) + chronDists(i, j, k).*(B{k}(2))); votes(i, j, k_elem_temp(k, :)) = votes(i, j, k_elem_temp(k, :)) + chronProb(i, j, k)/num_k(i)/num_layers; votes(i, j, rest_elem_temp(k, :)) = votes(i, j, rest_elem_temp(k, :)) + (1 - chronProb(i, j, k))/num_rest(i)/num_layers; end end end end Do you have any suggestions as to how I could adjust my code so that it runs in parallel? Thank you!

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  • Shrinking image by 57% and centering inside css structure

    - by Johua
    Hy, i'm really stuck. I'll go step by step and hope to make it short. This is the html structure: <li class="FAVwithimage"> <a href=""> <img src="pics/Joshua.png"> <span class="name">Joshua</span> <span class="comment">Developer</span> <span class="arrow"></span> </a> </li> Before i paste the css classes, some info about the exact goal to accomplish: Resize the picture (img) by 57%. If it cannot be done with css, then jquery/javascript solution. For example: Original pic is 240x240px, i need to resize it by 57%. That means that a pic of 400x400 would be bigger after resizing. After resizing, the picture needs to be centered vertical&horizontal inside a: 68x90 boundaries. So you have an LI element, wich has an A element, and inside A we have IMG, IMG is resized by 57% and centered where the maximum width can be of course 68px and maximum height 90px. No for that to work i was adding a SPAN element arround the IMG. This is what i was thinking: <li class="FAVwithimage"> <a href=""> <span class="picHolder"><img src="pics/Joshua.png"></span> <span class="name">Joshua</span> <span class="comment">Developer</span> <span class="arrow"></span> </a> </li> Then i would give the span element: display:block and w=68px, h=90px. But unforunatelly that didn't work. I know it's a long post but i'v did my best to describe it very simple. Beneath are the css classes and a picture to see what i need. li.FAVwithimage { height: 90px!important; } li.FAVwithimage a, li.FAVwithimage:hover a { height: 81px!important; } That's it what's relevant. I have not included the classes for: name,comment,arrow And now the classes that are incomplete and refer to IMG. li.FAVwithimage a span.picHolder{ /*put the picHolder to the beginning of the LI element*/ position: absolute; left: 0; top: 0; width: 68px; height: 90px; diplay:block; border:1px solid #F00; } Border is used just temporary to show the actuall picHolder. It is now on the beginning of LI, width and height is set. li.FAVwithimage span.picHolder img { max-width:68px!important; max-height:90px!important; } This is the class wich should shrink the pic by 57% and center inside picHolder Here I have a drawing describing what i need:

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  • Parallel.For(): Different results for simple addition

    - by TSS
    I'm just looking in to the new .NET 4.0 features. With that, I'm attempting a simple calculation using Parallel.For and a normal for(x;x;x) loop. However, I'm getting different results about 50% of the time (no code change). long sum = 0; Parallel.For(1, 10000, y => { sum += y; }); Console.WriteLine(sum.ToString()); sum = 0; for (int y = 1; y < 10000; y++) { sum += y; } Console.WriteLine(sum.ToString()); Surely I'm missing something simple or do not completely understand the concept. My guess is that the threads are trying to update "sum" at the same time. If so, is there an obvious way around it?

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  • file_get_contents to image and change quality

    - by Chris
    Hey I have some code that downloads an image from a remote server $data = file_get_contents("$rURL"); I want to then change the quality of this image, but do not want to save it out to a file first, how do I convert $data into an image that I can then use in imagecopyresampled? Thanks

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  • Algorithm to rotate an image 90 degrees in place? (No extra memory)

    - by user9876
    In an embedded C app, I have a large image that I'd like to rotate by 90 degrees. Currently I use the well-known simple algorithm to do this. However, this algorithm requires me to make another copy of the image. I'd like to avoid allocating memory for a copy, I'd rather rotate it in-place. Since the image isn't square, this is tricky. Does anyone know of a suitable algorithm?

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  • How to work with images(png's) of size 2-4Mb.

    - by Sam
    I am working with images of size 2 to 4MB. I want to edit image of resolution 1200x1600. performing scaling, traslation and rotation operations. I want to another images on that and saving it to photo album. My app is crashing(giving memory warning) after i successfully edit one image and save to album. I have releasing some images when i get memory warning. But still it crashes as i am working with 2 images of size 3MB each and context of size 1200x1600 and getting a image from the context at the same time. Is there any way to compress images and work with it by performing scaling, traslation and rotation operations?

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  • how to generate uncorrelated random numbers in repeated calls in parallel?

    - by user1446948
    I want to write a function which will be repeatedly called by other functions many times. Inside this function it is supposed to generate a lot of random numbers and this part will be treated in parallel. If only for one run, the seed can be chosen differently for each thread, so that the random numbers will be uncorrelated. However, if this function will be called the 2nd time, it seems that the random numbers will repeat unless the seed will be again changed during the later calls. So my question is, is there a good way to generate the random numbers or reset the seed so that the random numbers generated by repeated calls to this function and also by different threads are really random? Thank you.

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  • Custom Floating Point Representation

    - by Abion47
    I'm trying to write a parser that will read a particular file type, and I need to map the different data types to C# equivalents. Most of them aren't that difficult, but I'm having trouble wrapping my head around what "int16 with a bias of 14" means. I've deduced that it's some kind of floating point type, so my best bet would be to write a converter that would map it to a float, double, or decimal type. I'm not sure where to take it from here, though.

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  • Windows File I/O Reading

    - by eyeanand
    Currently working on open/read images in VC++. Some examples i came across on the internet use Windows.h I/O routines like ReadFile...but there seems to be inconsistency in there declaration. Here's what i have got. //So i have this function to load file BYTE* LoadFile ( int* width, int* height, long* size, LPCWSTR bmpfile ) { BITMAPFILEHEADER bmpheader; BITMAPINFOHEADER bmpinfo; DWORD bytesread = 0; HANDLE file = CreateFile ( bmpfile , GENERIC_READ, FILE_SHARE_READ,NULL, OPEN_EXISTING, FILE_FLAG_SEQUENTIAL_SCAN, NULL ); if ( NULL == file ) return NULL; if ( ReadFile ( file, &bmpheader, sizeof ( BITMAPFILEHEADER ),&bytesread, NULL ) == false ) { CloseHandle ( file ); return NULL; } . . . return appropriate value; } Now the ReadFile API function is declared as follows in WinBase.h WINBASEAPI BOOL WINAPI ReadFile( In HANDLE hFile, Out LPVOID lpBuffer, In DWORD nNumberOfBytesToRead, _Out_opt_ LPDWORD lpNumberOfBytesRead, _Inout_opt_ LPOVERLAPPED lpOverlapped ); And in MSDN examples... They call this function like this. ReadFile(hFile, chBuffer, BUFSIZE, &dwBytesRead, NULL) Which expects that "bytesRead" is sort of out parameter. so it gives me number of bytes read. But in my code ..it is giving error message. 'ReadFile' : cannot convert parameter 4 from 'LPDWORD *' to 'LPDWORD' so i just initialized bytesRead to 0 and passed by value.( which is wrong..but just to check if it works ). then it gives this exception Unhandled exception at 0x774406ae in ImProc.exe: 0xC0000005: Access violation writing location 0x00000000. Kindly suggest . Kindly tell if any code i missed out....including while forming the question itself. Thanks.

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  • How to avoid the Portlet Skin mismatch

    - by Martin Deh
    here are probably many on going debates whether to use portlets or taskflows in a WebCenter custom portal application.  Usually the main battle on which side to take in these debates are centered around which technology enables better performance.  The good news is that both of my colleagues, Maiko Rocha and George Maggessy have posted their respective views on this topic so I will not have to further the discussion.  However, if you do plan to use portlets in a WebCenter custom portal application, this post will help you not have the "portlet skin mismatch" issue.   An example of the presence of the mismatch can be view from the applications log: The skin customsharedskin.desktop specified on the requestMap will be used even though the consumer's skin's styleSheetDocumentId on the requestMap does not match the local skin's styleSheetDocument's id. This will impact performance since the consumer and producer stylesheets cannot be shared. The producer styleclasses will not be compressed to avoid conflicts. A reason the ids do not match may be the jars are not identical on the producer and the consumer. For example, one might have trinidad-skins.xml's skin-additions in a jar file on the class path that the other does not have. Notice that due to the mismatch the portlet's CSS will not be able to be compressed, which will most like impact performance in the portlet's consuming portal. The first part of the blog will define the portlet mismatch and cover some debugging tips that can help you solve the portlet mismatch issue.  Following that I will give a complete example of the creating, using and sharing a shared skin in both a portlet producer and the consumer application. Portlet Mismatch Defined  In general, when you consume/render an ADF page (or task flow) using the ADF Portlet bridge, the portlet (producer) would try to use the skin of the consumer page - this is called skin-sharing. When the producer cannot match the consumer skin, the portlet would generate its own stylesheet and reference it from its markup - this is called mismatched-skin. This can happen because: The consumer and producer use different versions of ADF Faces, or The consumer has additional skin-additions that the producer doesn't have or vice-versa, or The producer does not have the consumer skin For case (1) & (2) above, the producer still uses the consumer skin ID to render its markup. For case (3), the producer would default to using portlet skin. If there is a skin mis-match then there may be a performance hit because: The browser needs to fetch this extra stylesheet (though it should be cached unless expires caching is turned off) The generated portlet markup uses uncompressed styles resulting in a larger markup It is often not obvious when a skin mismatch occurs, unless you look for either of these indicators: The log messages in the producer log, for example: The skin blafplus-rich.desktop specified on the requestMap will not be used because the styleSheetDocument id on the requestMap does not match the local skin's styleSheetDocument's id. It could mean the jars are not identical. For example, one might have trinidad-skins.xml's skin-additions in a jar file on the class path that the other does not have. View the portlet markup inside the iframe, there should be a <link> tag to the portlet stylesheet resource like this (note the CSS is proxied through consumer's resourceproxy): <link rel=\"stylesheet\" charset=\"UTF-8\" type=\"text/css\" href=\"http:.../resourceproxy/portletId...252525252Fadf%252525252Fstyles%252525252Fcache%252525252Fblafplus-rich-portlet-d1062g-en-ltr-gecko.css... Using HTTP monitoring tool (eg, firebug, httpwatch), you can see a request is made to the portlet stylesheet resource (see URL above) There are a number of reasons for mismatched-skin. For skin to match the producer and consumer must match the following configurations: The ADF Faces version (different versions may have different style selectors) Style Compression, this is defined in the web.xml (default value is false, i.e. compression is ON) Tonal styles or themes, also defined in the web.xml via context-params The same skin additions (jars with skin) are available for both producer and consumer.  Skin additions are defined in the trinidad-skins.xml, using the <skin-addition> tags. These are then aggregated from all the jar files in the classpath. If there's any jar that exists on the producer but not the consumer, or vice veras, you get a mismatch. Debugging Tips  Ensure the style compression and tonal styles/themes match on the consumer and producer, by looking at the web.xml documents for the consumer & producer applications It is bit more involved to determine if the jars match.  However, you can enable the Trinidad logging to show which skin-addition it is processing.  To enable this feature, update the logging.xml log level of both the producer and consumer WLS to FINEST.  For example, in the case of the WebLogic server used by JDeveloper: $JDEV_USER_DIR/system<version number>/DefaultDomain/config/fmwconfig/servers/DefaultServer/logging.xml Add a new entry: <logger name="org.apache.myfaces.trinidadinternal.skin.SkinUtils" level="FINEST"/> Restart WebLogic.  Run the consumer page, you should see the following logging in both the consumer and producer log files. Any entries that don't match is the cause of the mismatch.  The following is an example of what the log will produce with this setting: [SRC_CLASS: org.apache.myfaces.trinidadinternal.skin.SkinUtils] [APP: WebCenter] [SRC_METHOD: _getMetaInfSkinsNodeList] Processing skin URL:zip:/tmp/_WL_user/oracle.webcenter.skin/in1ar8/APP-INF/lib/announcement-skin.jar!/META-INF/trinidad-skins.xml Processing skin URL:zip:/tmp/_WL_user/oracle.webcenter.skin/in1ar8/APP-INF/lib/calendar-skin.jar!/META-INF/trinidad-skins.xml Processing skin URL:zip:/tmp/_WL_user/oracle.webcenter.skin/in1ar8/APP-INF/lib/custComps-skin.jar!/META-INF/trinidad-skins.xml Processing skin URL:zip:/tmp/_WL_user/oracle.webcenter.skin/in1ar8/APP-INF/lib/forum-skin.jar!/META-INF/trinidad-skins.xml Processing skin URL:zip:/tmp/_WL_user/oracle.webcenter.skin/in1ar8/APP-INF/lib/page-service-skin.jar!/META-INF/trinidad-skins.xml Processing skin URL:zip:/tmp/_WL_user/oracle.webcenter.skin/in1ar8/APP-INF/lib/peopleconnections-kudos-skin.jar!/META-INF/trinidad-skins.xml Processing skin URL:zip:/tmp/_WL_user/oracle.webcenter.skin/in1ar8/APP-INF/lib/peopleconnections-wall-skin.jar!/META-INF/trinidad-skins.xml Processing skin URL:zip:/tmp/_WL_user/oracle.webcenter.skin/in1ar8/APP-INF/lib/portlet-client-adf-skin.jar!/META-INF/trinidad-skins.xml Processing skin URL:zip:/tmp/_WL_user/oracle.webcenter.skin/in1ar8/APP-INF/lib/rtc-skin.jar!/META-INF/trinidad-skins.xml Processing skin URL:zip:/tmp/_WL_user/oracle.webcenter.skin/in1ar8/APP-INF/lib/serviceframework-skin.jar!/META-INF/trinidad-skins.xml Processing skin URL:zip:/tmp/_WL_user/oracle.webcenter.skin/in1ar8/APP-INF/lib/smarttag-skin.jar!/META-INF/trinidad-skins.xml Processing skin URL:zip:/tmp/_WL_user/oracle.webcenter.skin/in1ar8/APP-INF/lib/spaces-service-skins.jar!/META-INF/trinidad-skins.xml Processing skin URL:zip:/tmp/_WL_user/oracle.webcenter.composer/3yo7j/WEB-INF/lib/custComps-skin.jar!/META-INF/trinidad-skins.xml Processing skin URL:zip:/tmp/_WL_user/adf.oracle.domain.webapp/q433f9/WEB-INF/lib/adf-richclient-impl-11.jar!/META-INF/trinidad-skins.xml Processing skin URL:zip:/tmp/_WL_user/adf.oracle.domain.webapp/q433f9/WEB-INF/lib/dvt-faces.jar!/META-INF/trinidad-skins.xml Processing skin URL:zip:/tmp/_WL_user/adf.oracle.domain.webapp/q433f9/WEB-INF/lib/dvt-trinidad.jar!/META-INF/trinidad-skins.xml   The Complete Example The first step is to create the shared library.  The WebCenter documentation covering this is located here in section 15.7.  In addition, our ADF guru Frank Nimphius also covers this in hes blog.  Here are my steps (in JDeveloper) to create the skin that will be used as the shared library for both the portlet producer and consumer. Create a new Generic Application Give application name (i.e. MySharedSkin) Give a project name (i.e. MySkinProject) Leave Project Technologies blank (none selected), and click Finish Create the trinidad-skins.xml Right-click on the MySkinProject node in the Application Navigator and select "New" In the New Galley, click on "General", select "File" from the Items, and click OK In the Create File dialog, name the file trinidad-skins.xml, and (IMPORTANT) give the directory path to MySkinProject\src\META-INF In the trinidad-skins.xml, complete the skin entry.  for example: <?xml version="1.0" encoding="windows-1252" ?> <skins xmlns="http://myfaces.apache.org/trinidad/skin">   <skin>     <id>mysharedskin.desktop</id>     <family>mysharedskin</family>     <extends>fusionFx-v1.desktop</extends>     <style-sheet-name>css/mysharedskin.css</style-sheet-name>   </skin> </skins> Create CSS file In the Application Navigator, right click on the META-INF folder (where the trinidad-skins.xml is located), and select "New" In the New Gallery, select Web-Tier-> HTML, CSS File from the the Items and click OK In the Create Cascading Style Sheet dialog, give the name (i.e. mysharedskin.css) Ensure that the Directory path is the under the META-INF (i.e. MySkinProject\src\META-INF\css) Once the new CSS opens in the editor, add in a style selector.  For example, this selector will style the background of a particular panelGroupLayout: af|panelGroupLayout.customPGL{     background-color:Fuchsia; } Create the MANIFEST.MF (used for deployment JAR) In the Application Navigator, right click on the META-INF folder (where the trinidad-skins.xml is located), and select "New" In the New Galley, click on "General", select "File" from the Items, and click OK In the Create File dialog, name the file MANIFEST.MF, and (IMPORTANT) ensure that the directory path is to MySkinProject\src\META-INF Complete the MANIFEST.MF, where the extension name is the shared library name Manifest-Version: 1.1 Created-By: Martin Deh Implementation-Title: mysharedskin Extension-Name: mysharedskin.lib.def Specification-Version: 1.0.1 Implementation-Version: 1.0.1 Implementation-Vendor: MartinDeh Create new Deployment Profile Right click on the MySkinProject node, and select New From the New Gallery, select General->Deployment Profiles, Shared Library JAR File from Items, and click OK In the Create Deployment Profile dialog, give name (i.e.mysharedskinlib) and click OK In the Edit JAR Deployment dialog, un-check Include Manifest File option  Select Project Output->Contributors, and check Project Source Path Select Project Output->Filters, ensure that all items under the META-INF folder are selected Click OK to exit the Project Properties dialog Deploy the shared lib to WebLogic (start server before steps) Right click on MySkin Project and select Deploy For this example, I will deploy to JDeverloper WLS In the Deploy dialog, select Deploy to Weblogic Application Server and click Next Choose IntegratedWebLogicServer and click Next Select Deploy to selected instances in the domain radio, select Default Server (note: server must be already started), and ensure Deploy as a shared Library radio is selected Click Finish Open the WebLogic console to see the deployed shared library The following are the steps to create a simple test Portlet Create a new WebCenter Portal - Portlet Producer Application In the Create Portlet Producer dialog, select default settings and click Finish Right click on the Portlets node and select New IIn the New Gallery, select Web-Tier->Portlets, Standards-based Java Portlet (JSR 286) and click OK In the General Portlet information dialog, give portlet name (i.e. MyPortlet) and click Next 2 times, stopping at Step 3 In the Content Types, select the "view" node, in the Implementation Method, select the Generate ADF-Faces JSPX radio and click Finish Once the portlet code is generated, open the view.jspx in the source editor Based on the simple CSS entry, which sets the background color of a panelGroupLayout, replace the <af:form/> tag with the example code <af:form>         <af:panelGroupLayout id="pgl1" styleClass="customPGL">           <af:outputText value="background from shared lib skin" id="ot1"/>         </af:panelGroupLayout>  </af:form> Since this portlet is to use the shared library skin, in the generated trinidad-config.xml, remove both the skin-family tag and the skin-version tag In the Application Resources view, under Descriptors->META-INF, double-click to open the weblogic-application.xml Add a library reference to the shared skin library (note: the library-name must match the extension-name declared in the MANIFEST.MF):  <library-ref>     <library-name>mysharedskin.lib.def</library-name>  </library-ref> Notice that a reference to oracle.webcenter.skin exists.  This is important if this portlet is going to be consumed by a WebCenter Portal application.  If this tag is not present, the portlet skin mismatch will happen.  Configure the portlet for deployment Create Portlet deployment WAR Right click on the Portlets node and select New In the New Gallery, select Deployment Profiles, WAR file from Items and click OK In the Create Deployment Profile dialog, give name (i.e. myportletwar), click OK Keep all of the defaults, however, remember the Context Root entry (i.e. MyPortlet4SharedLib-Portlets-context-root, this will be needed to obtain the producer WSDL URL) Click OK, then OK again to exit from the Properties dialog Since the weblogic-application.xml has to be included in the deployment, the portlet must be deployed as a WAR, within an EAR In the Application dropdown, select Deploy->New Deployment Profile... By default EAR File has been selected, click OK Give Deployment Profile (EAR) a name (i.e. MyPortletProducer) and click OK In the Properties dialog, select Application Assembly and ensure that the myportletwar is checked Keep all of the other defaults and click OK For this demo, un-check the Auto Generate ..., and all of the Security Deployment Options, click OK Save All In the Application dropdown, select Deploy->MyPortletProducer In the Deployment Action, select Deploy to Application Server, click Next Choose IntegratedWebLogicServer and click Next Select Deploy to selected instances in the domain radio, select Default Server (note: server must be already started), and ensure Deploy as a standalone Application radio is selected The select deployment type (identifying the deployment as a JSR 286 portlet) dialog appears.  Keep default radio "Yes" selection and click OK Open the WebLogic console to see the deployed Portlet The last step is to create the test portlet consuming application.  This will be done using the OOTB WebCenter Portal - Framework Application.  Create the Portlet Producer Connection In the JDeveloper Deployment log, copy the URL of the portlet deployment (i.e. http://localhost:7101/MyPortlet4SharedLib-Portlets-context-root Open a browser and paste in the URL.  The Portlet information page should appear.  Click on the WSRP v2 WSDL link Copy the URL from the browser (i.e. http://localhost:7101/MyPortlet4SharedLib-Portlets-context-root/portlets/wsrp2?WSDL) In the Application Resources view, right click on the Connections folder and select New Connection->WSRP Connection Give the producer a name or accept the default, click Next Enter (paste in) the WSDL URL, click Next If connection to Portlet is succesful, Step 3 (Specify Additional ...) should appear.  Accept defaults and click Finish Add the portlet to a test page Open the home.jspx.  Note in the visual editor, the orange dashed border, which identifies the panelCustomizable tag. From the Application Resources. select the MyPortlet portlet node, and drag and drop the node into the panelCustomizable section.  A Confirm Portlet Type dialog appears, keep default ADF Rich Portlet and click OK Configure the portlet to use the shared skin library Open the weblogic-application.xml and add the library-ref entry (mysharedskin.lib.def) for the shared skin library.  See create portlet example above for the steps Since by default, the custom portal using a managed bean to (dynamically) determine the skin family, the default trinidad-config.xml will need to be altered Open the trinidad-config.xml in the editor and replace the EL (preferenceBean) for the skin-family tag, with mysharedskin (this is the skin-family named defined in the trinidad-skins.xml) Remove the skin-version tag Right click on the index.html to test the application   Notice that the JDeveloper log view does not have any reporting of a skin mismatch.  In addition, since I have configured the extra logging outlined in debugging section above, I can see the processed skin jar in both the producer and consumer logs: <SkinUtils> <_getMetaInfSkinsNodeList> Processing skin URL:zip:/JDeveloper/system11.1.1.6.38.61.92/DefaultDomain/servers/DefaultServer/upload/mysharedskin.lib.def/[email protected]/app/mysharedskinlib.jar!/META-INF/trinidad-skins.xml 

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  • How can Agile methodologies be adapted to High Volume processing system development?

    - by luckyluke
    I am developing high volume processing systems. Like mathematical models that calculate various parameters based on millions of records, calculated derived fields over milions of records, process huge files having transactions etc... I am well aware of unit testing methodologies and if my code is in C# I have no problem in unit testing it. Problem is I often have code in T-SQL, C# code that is a SQL stored assembly, and SSIS workflow with a good amount of logic (and outcomes etc) or some SAS process. What is the approach YOu use when developing such systems. I usually develop several tests as Stored procedures in a designed schema(TEST) and then automatically run them overnight and check out the results. But this is only for T-SQL. And Continous integration IS hard. But the problem is with testing SSIS packages. How do You test it? What is Your preferred approach for stubbing data into tables (especially if You need a lot data initialization). I have some approach derived over the years but maybe I am just not reading enough articles. So Banking, Telecom, Risk developers out there. How do You test your mission critical apps that process milions of records at end day, month end etc? What frameworks do You use? How do You validate that Your ssis package is Correct (as You develop it)/ How do You achieve continous integration in such an environment (Personally I never got there)? I hope this is not to open-ended question. How do You test Your map-reduce jobs for example (i do not use hadoop but this is quite similar). luke Hope that this is not too open ended

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  • Performing a Depth First Search iteratively using async/parallel processing?

    - by Prabhu
    Here is a method that does a DFS search and returns a list of all items given a top level item id. How could I modify this to take advantage of parallel processing? Currently, the call to get the sub items is made one by one for each item in the stack. It would be nice if I could get the sub items for multiple items in the stack at the same time, and populate my return list faster. How could I do this (either using async/await or TPL, or anything else) in a thread safe manner? private async Task<IList<Item>> GetItemsAsync(string topItemId) { var items = new List<Item>(); var topItem = await GetItemAsync(topItemId); Stack<Item> stack = new Stack<Item>(); stack.Push(topItem); while (stack.Count > 0) { var item = stack.Pop(); items.Add(item); var subItems = await GetSubItemsAsync(item.SubId); foreach (var subItem in subItems) { stack.Push(subItem); } } return items; } I was thinking of something along these lines, but it's not coming together: var tasks = stack.Select(async item => { items.Add(item); var subItems = await GetSubItemsAsync(item.SubId); foreach (var subItem in subItems) { stack.Push(subItem); } }).ToList(); if (tasks.Any()) await Task.WhenAll(tasks); The language I'm using is C#.

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  • 2d game view camera zoom, rotation & offset using 'Filter' / 'Shader' processing?

    - by Arthur Wulf White
    I wish to add the ability to zoom-in, zoom-out, rotate and move the view in a top-down view over a collection of points and lines in a large 2d map. I split the map into a grid so I only need to render the points that are 'near' the camera. My question is, how do I render a point A(Xp,Yp) assuming the following details: Offset of the camera pov from the origin of the map is: Xc, Yc Meaning the camera center is positioned on top of that point. If there's a point in Xc, Yc it is positioned in the center of the screen. The rotation angle is: alpha The scale is: S Read my answer first. I am thinking there is more optimized solution, thanks. My question is how to include the following improvement: I read in the AS3 Bible book that: In regards to ShaderInput, You can use these methods to coerce Pixel Bender to crunch huge sets of data masquerading as images, without doing too much work on the ActionScript side to make them look like images. Meaning if I am performing the same linear function on a lot of items, I can do it all at once if I use Shaders correctly and save processing time. Does anyone know how that is accomplished? Here is a sample of what I mean: http://wonderfl.net/c/eFp0/

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  • C#/.NET Little Wonders: The ConcurrentDictionary

    - by James Michael Hare
    Once again we consider some of the lesser known classes and keywords of C#.  In this series of posts, we will discuss how the concurrent collections have been developed to help alleviate these multi-threading concerns.  Last week’s post began with a general introduction and discussed the ConcurrentStack<T> and ConcurrentQueue<T>.  Today's post discusses the ConcurrentDictionary<T> (originally I had intended to discuss ConcurrentBag this week as well, but ConcurrentDictionary had enough information to create a very full post on its own!).  Finally next week, we shall close with a discussion of the ConcurrentBag<T> and BlockingCollection<T>. For more of the "Little Wonders" posts, see the index here. Recap As you'll recall from the previous post, the original collections were object-based containers that accomplished synchronization through a Synchronized member.  While these were convenient because you didn't have to worry about writing your own synchronization logic, they were a bit too finely grained and if you needed to perform multiple operations under one lock, the automatic synchronization didn't buy much. With the advent of .NET 2.0, the original collections were succeeded by the generic collections which are fully type-safe, but eschew automatic synchronization.  This cuts both ways in that you have a lot more control as a developer over when and how fine-grained you want to synchronize, but on the other hand if you just want simple synchronization it creates more work. With .NET 4.0, we get the best of both worlds in generic collections.  A new breed of collections was born called the concurrent collections in the System.Collections.Concurrent namespace.  These amazing collections are fine-tuned to have best overall performance for situations requiring concurrent access.  They are not meant to replace the generic collections, but to simply be an alternative to creating your own locking mechanisms. Among those concurrent collections were the ConcurrentStack<T> and ConcurrentQueue<T> which provide classic LIFO and FIFO collections with a concurrent twist.  As we saw, some of the traditional methods that required calls to be made in a certain order (like checking for not IsEmpty before calling Pop()) were replaced in favor of an umbrella operation that combined both under one lock (like TryPop()). Now, let's take a look at the next in our series of concurrent collections!For some excellent information on the performance of the concurrent collections and how they perform compared to a traditional brute-force locking strategy, see this wonderful whitepaper by the Microsoft Parallel Computing Platform team here. ConcurrentDictionary – the fully thread-safe dictionary The ConcurrentDictionary<TKey,TValue> is the thread-safe counterpart to the generic Dictionary<TKey, TValue> collection.  Obviously, both are designed for quick – O(1) – lookups of data based on a key.  If you think of algorithms where you need lightning fast lookups of data and don’t care whether the data is maintained in any particular ordering or not, the unsorted dictionaries are generally the best way to go. Note: as a side note, there are sorted implementations of IDictionary, namely SortedDictionary and SortedList which are stored as an ordered tree and a ordered list respectively.  While these are not as fast as the non-sorted dictionaries – they are O(log2 n) – they are a great combination of both speed and ordering -- and still greatly outperform a linear search. Now, once again keep in mind that if all you need to do is load a collection once and then allow multi-threaded reading you do not need any locking.  Examples of this tend to be situations where you load a lookup or translation table once at program start, then keep it in memory for read-only reference.  In such cases locking is completely non-productive. However, most of the time when we need a concurrent dictionary we are interleaving both reads and updates.  This is where the ConcurrentDictionary really shines!  It achieves its thread-safety with no common lock to improve efficiency.  It actually uses a series of locks to provide concurrent updates, and has lockless reads!  This means that the ConcurrentDictionary gets even more efficient the higher the ratio of reads-to-writes you have. ConcurrentDictionary and Dictionary differences For the most part, the ConcurrentDictionary<TKey,TValue> behaves like it’s Dictionary<TKey,TValue> counterpart with a few differences.  Some notable examples of which are: Add() does not exist in the concurrent dictionary. This means you must use TryAdd(), AddOrUpdate(), or GetOrAdd().  It also means that you can’t use a collection initializer with the concurrent dictionary. TryAdd() replaced Add() to attempt atomic, safe adds. Because Add() only succeeds if the item doesn’t already exist, we need an atomic operation to check if the item exists, and if not add it while still under an atomic lock. TryUpdate() was added to attempt atomic, safe updates. If we want to update an item, we must make sure it exists first and that the original value is what we expected it to be.  If all these are true, we can update the item under one atomic step. TryRemove() was added to attempt atomic, safe removes. To safely attempt to remove a value we need to see if the key exists first, this checks for existence and removes under an atomic lock. AddOrUpdate() was added to attempt an thread-safe “upsert”. There are many times where you want to insert into a dictionary if the key doesn’t exist, or update the value if it does.  This allows you to make a thread-safe add-or-update. GetOrAdd() was added to attempt an thread-safe query/insert. Sometimes, you want to query for whether an item exists in the cache, and if it doesn’t insert a starting value for it.  This allows you to get the value if it exists and insert if not. Count, Keys, Values properties take a snapshot of the dictionary. Accessing these properties may interfere with add and update performance and should be used with caution. ToArray() returns a static snapshot of the dictionary. That is, the dictionary is locked, and then copied to an array as a O(n) operation.  GetEnumerator() is thread-safe and efficient, but allows dirty reads. Because reads require no locking, you can safely iterate over the contents of the dictionary.  The only downside is that, depending on timing, you may get dirty reads. Dirty reads during iteration The last point on GetEnumerator() bears some explanation.  Picture a scenario in which you call GetEnumerator() (or iterate using a foreach, etc.) and then, during that iteration the dictionary gets updated.  This may not sound like a big deal, but it can lead to inconsistent results if used incorrectly.  The problem is that items you already iterated over that are updated a split second after don’t show the update, but items that you iterate over that were updated a split second before do show the update.  Thus you may get a combination of items that are “stale” because you iterated before the update, and “fresh” because they were updated after GetEnumerator() but before the iteration reached them. Let’s illustrate with an example, let’s say you load up a concurrent dictionary like this: 1: // load up a dictionary. 2: var dictionary = new ConcurrentDictionary<string, int>(); 3:  4: dictionary["A"] = 1; 5: dictionary["B"] = 2; 6: dictionary["C"] = 3; 7: dictionary["D"] = 4; 8: dictionary["E"] = 5; 9: dictionary["F"] = 6; Then you have one task (using the wonderful TPL!) to iterate using dirty reads: 1: // attempt iteration in a separate thread 2: var iterationTask = new Task(() => 3: { 4: // iterates using a dirty read 5: foreach (var pair in dictionary) 6: { 7: Console.WriteLine(pair.Key + ":" + pair.Value); 8: } 9: }); And one task to attempt updates in a separate thread (probably): 1: // attempt updates in a separate thread 2: var updateTask = new Task(() => 3: { 4: // iterates, and updates the value by one 5: foreach (var pair in dictionary) 6: { 7: dictionary[pair.Key] = pair.Value + 1; 8: } 9: }); Now that we’ve done this, we can fire up both tasks and wait for them to complete: 1: // start both tasks 2: updateTask.Start(); 3: iterationTask.Start(); 4:  5: // wait for both to complete. 6: Task.WaitAll(updateTask, iterationTask); Now, if I you didn’t know about the dirty reads, you may have expected to see the iteration before the updates (such as A:1, B:2, C:3, D:4, E:5, F:6).  However, because the reads are dirty, we will quite possibly get a combination of some updated, some original.  My own run netted this result: 1: F:6 2: E:6 3: D:5 4: C:4 5: B:3 6: A:2 Note that, of course, iteration is not in order because ConcurrentDictionary, like Dictionary, is unordered.  Also note that both E and F show the value 6.  This is because the output task reached F before the update, but the updates for the rest of the items occurred before their output (probably because console output is very slow, comparatively). If we want to always guarantee that we will get a consistent snapshot to iterate over (that is, at the point we ask for it we see precisely what is in the dictionary and no subsequent updates during iteration), we should iterate over a call to ToArray() instead: 1: // attempt iteration in a separate thread 2: var iterationTask = new Task(() => 3: { 4: // iterates using a dirty read 5: foreach (var pair in dictionary.ToArray()) 6: { 7: Console.WriteLine(pair.Key + ":" + pair.Value); 8: } 9: }); The atomic Try…() methods As you can imagine TryAdd() and TryRemove() have few surprises.  Both first check the existence of the item to determine if it can be added or removed based on whether or not the key currently exists in the dictionary: 1: // try add attempts an add and returns false if it already exists 2: if (dictionary.TryAdd("G", 7)) 3: Console.WriteLine("G did not exist, now inserted with 7"); 4: else 5: Console.WriteLine("G already existed, insert failed."); TryRemove() also has the virtue of returning the value portion of the removed entry matching the given key: 1: // attempt to remove the value, if it exists it is removed and the original is returned 2: int removedValue; 3: if (dictionary.TryRemove("C", out removedValue)) 4: Console.WriteLine("Removed C and its value was " + removedValue); 5: else 6: Console.WriteLine("C did not exist, remove failed."); Now TryUpdate() is an interesting creature.  You might think from it’s name that TryUpdate() first checks for an item’s existence, and then updates if the item exists, otherwise it returns false.  Well, note quite... It turns out when you call TryUpdate() on a concurrent dictionary, you pass it not only the new value you want it to have, but also the value you expected it to have before the update.  If the item exists in the dictionary, and it has the value you expected, it will update it to the new value atomically and return true.  If the item is not in the dictionary or does not have the value you expected, it is not modified and false is returned. 1: // attempt to update the value, if it exists and if it has the expected original value 2: if (dictionary.TryUpdate("G", 42, 7)) 3: Console.WriteLine("G existed and was 7, now it's 42."); 4: else 5: Console.WriteLine("G either didn't exist, or wasn't 7."); The composite Add methods The ConcurrentDictionary also has composite add methods that can be used to perform updates and gets, with an add if the item is not existing at the time of the update or get. The first of these, AddOrUpdate(), allows you to add a new item to the dictionary if it doesn’t exist, or update the existing item if it does.  For example, let’s say you are creating a dictionary of counts of stock ticker symbols you’ve subscribed to from a market data feed: 1: public sealed class SubscriptionManager 2: { 3: private readonly ConcurrentDictionary<string, int> _subscriptions = new ConcurrentDictionary<string, int>(); 4:  5: // adds a new subscription, or increments the count of the existing one. 6: public void AddSubscription(string tickerKey) 7: { 8: // add a new subscription with count of 1, or update existing count by 1 if exists 9: var resultCount = _subscriptions.AddOrUpdate(tickerKey, 1, (symbol, count) => count + 1); 10:  11: // now check the result to see if we just incremented the count, or inserted first count 12: if (resultCount == 1) 13: { 14: // subscribe to symbol... 15: } 16: } 17: } Notice the update value factory Func delegate.  If the key does not exist in the dictionary, the add value is used (in this case 1 representing the first subscription for this symbol), but if the key already exists, it passes the key and current value to the update delegate which computes the new value to be stored in the dictionary.  The return result of this operation is the value used (in our case: 1 if added, existing value + 1 if updated). Likewise, the GetOrAdd() allows you to attempt to retrieve a value from the dictionary, and if the value does not currently exist in the dictionary it will insert a value.  This can be handy in cases where perhaps you wish to cache data, and thus you would query the cache to see if the item exists, and if it doesn’t you would put the item into the cache for the first time: 1: public sealed class PriceCache 2: { 3: private readonly ConcurrentDictionary<string, double> _cache = new ConcurrentDictionary<string, double>(); 4:  5: // adds a new subscription, or increments the count of the existing one. 6: public double QueryPrice(string tickerKey) 7: { 8: // check for the price in the cache, if it doesn't exist it will call the delegate to create value. 9: return _cache.GetOrAdd(tickerKey, symbol => GetCurrentPrice(symbol)); 10: } 11:  12: private double GetCurrentPrice(string tickerKey) 13: { 14: // do code to calculate actual true price. 15: } 16: } There are other variations of these two methods which vary whether a value is provided or a factory delegate, but otherwise they work much the same. Oddities with the composite Add methods The AddOrUpdate() and GetOrAdd() methods are totally thread-safe, on this you may rely, but they are not atomic.  It is important to note that the methods that use delegates execute those delegates outside of the lock.  This was done intentionally so that a user delegate (of which the ConcurrentDictionary has no control of course) does not take too long and lock out other threads. This is not necessarily an issue, per se, but it is something you must consider in your design.  The main thing to consider is that your delegate may get called to generate an item, but that item may not be the one returned!  Consider this scenario: A calls GetOrAdd and sees that the key does not currently exist, so it calls the delegate.  Now thread B also calls GetOrAdd and also sees that the key does not currently exist, and for whatever reason in this race condition it’s delegate completes first and it adds its new value to the dictionary.  Now A is done and goes to get the lock, and now sees that the item now exists.  In this case even though it called the delegate to create the item, it will pitch it because an item arrived between the time it attempted to create one and it attempted to add it. Let’s illustrate, assume this totally contrived example program which has a dictionary of char to int.  And in this dictionary we want to store a char and it’s ordinal (that is, A = 1, B = 2, etc).  So for our value generator, we will simply increment the previous value in a thread-safe way (perhaps using Interlocked): 1: public static class Program 2: { 3: private static int _nextNumber = 0; 4:  5: // the holder of the char to ordinal 6: private static ConcurrentDictionary<char, int> _dictionary 7: = new ConcurrentDictionary<char, int>(); 8:  9: // get the next id value 10: public static int NextId 11: { 12: get { return Interlocked.Increment(ref _nextNumber); } 13: } Then, we add a method that will perform our insert: 1: public static void Inserter() 2: { 3: for (int i = 0; i < 26; i++) 4: { 5: _dictionary.GetOrAdd((char)('A' + i), key => NextId); 6: } 7: } Finally, we run our test by starting two tasks to do this work and get the results… 1: public static void Main() 2: { 3: // 3 tasks attempting to get/insert 4: var tasks = new List<Task> 5: { 6: new Task(Inserter), 7: new Task(Inserter) 8: }; 9:  10: tasks.ForEach(t => t.Start()); 11: Task.WaitAll(tasks.ToArray()); 12:  13: foreach (var pair in _dictionary.OrderBy(p => p.Key)) 14: { 15: Console.WriteLine(pair.Key + ":" + pair.Value); 16: } 17: } If you run this with only one task, you get the expected A:1, B:2, ..., Z:26.  But running this in parallel you will get something a bit more complex.  My run netted these results: 1: A:1 2: B:3 3: C:4 4: D:5 5: E:6 6: F:7 7: G:8 8: H:9 9: I:10 10: J:11 11: K:12 12: L:13 13: M:14 14: N:15 15: O:16 16: P:17 17: Q:18 18: R:19 19: S:20 20: T:21 21: U:22 22: V:23 23: W:24 24: X:25 25: Y:26 26: Z:27 Notice that B is 3?  This is most likely because both threads attempted to call GetOrAdd() at roughly the same time and both saw that B did not exist, thus they both called the generator and one thread got back 2 and the other got back 3.  However, only one of those threads can get the lock at a time for the actual insert, and thus the one that generated the 3 won and the 3 was inserted and the 2 got discarded.  This is why on these methods your factory delegates should be careful not to have any logic that would be unsafe if the value they generate will be pitched in favor of another item generated at roughly the same time.  As such, it is probably a good idea to keep those generators as stateless as possible. Summary The ConcurrentDictionary is a very efficient and thread-safe version of the Dictionary generic collection.  It has all the benefits of type-safety that it’s generic collection counterpart does, and in addition is extremely efficient especially when there are more reads than writes concurrently. Tweet Technorati Tags: C#, .NET, Concurrent Collections, Collections, Little Wonders, Black Rabbit Coder,James Michael Hare

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  • How to rate-limit concurrent sessions with nginx or haproxy?

    - by bantic
    I'm currently using nginx to reverse-proxy requests from web clients that are doing long-polling to an upstream. Since we're doing long polling (as opposed to websockets), when a client connects it will make multiple http connections to the server in serial, re-establishing a connection every time the server sends it some data (or timing out and re-establishing if the server has nothing to say for 10 seconds). What I'd like to do is limit the number of concurrent web clients. Since the clients are constantly making new HTTP requests instead of keeping a single request open, it's a little tricky to count the total number of web clients (because it's not the same as total number of concurrently connected http clients). The method I've come up with is to track http requests by the originating IP address, and store the IP address somewhere with a TTL of 20 seconds. If a request comes in whose IP isn't recognized, then we check the total number of unexpired stored IP addresses; if that's less than the maximum then we allow this request through. And if a request comes in with an IP address that we can find in the look-up table that hasn't yet expired, then it is allowed through as well. All requests that are allowed through have their IPs added to the table (if not there before) and the TTL refreshed to 20 seconds again. I had actually whipped something together that worked correctly this way using nginx along with the Redis 2.0 Nginx Module (and the nginx lua module to simplify the conditional branching), using redis to store my IP addresses with a TTL (the SETEX command), and checking the table size with the DBSIZE command. This worked but the performance was horrible. nginx and redis ended up using lots of cpu and the machine could only handle a very small number of concurrent requests. The new stick-table and tracking counters that were added to Haproxy in version 1.5 (via a commission from serverfault) seem like they might be ideal to implement exactly this sort of rate limiting, because the stick-table can track IP addresses and automatically expire entries. However, I don't see an easy way to get a total count of the unexpired entries in the stick table, which would be necessary to know the number of connected web clients. I'm curious if anyone has any suggestions, for nginx or haproxy or even for something else not mentioned here that I haven't thought of yet.

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