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  • Amazon Product API: "Your request is missing a required parameter combination" on Blended ItemSearch

    - by Daniel Schaffer
    I'm having some problems trying to do an ItemSearch on the Blended index using the Amazon Product API. According to the documentation, Blended requests cannot specify the MerchantId parameter - and indeed, if I try to include it I get an error telling me so. However, when I don't include it, I get an error telling me that my request is missing a required parameter combination and that a valid combination includes MerchantId... what the hell? Here's the XML response: <Items xmlns="http://webservices.amazon.com/AWSECommerceService/2005-10-05"> <Request> <IsValid>False</IsValid> <ItemSearchRequest> <Availability>Available</Availability> <Condition>All</Condition> <Keywords> home theater pc and other geekery</Keywords> <ResponseGroup>Similarities</ResponseGroup> <ResponseGroup>SalesRank</ResponseGroup> <ResponseGroup>OfferSummary</ResponseGroup> <ResponseGroup>Small</ResponseGroup> <ResponseGroup>Images</ResponseGroup> <SearchIndex>Blended</SearchIndex> </ItemSearchRequest> <Errors> <Error> <Code>AWS.MissingParameterCombination</Code> <Message>Your request is missing a required parameter combination. Required parameter combinations include MerchantId, Availability.</Message> </Error> </Errors> </Request> </Items> The failing requests are being sent as part of batches with other requests that are succeeding. I'm using REST to send my requests, so here's an example of a request: http://ecs.amazonaws.com/onca/xml?AWSAccessKeyId=-------------& ItemSearch.1.Keywords=Mates%20of%20State& ItemSearch.1.MerchantId=Amazon& ItemSearch.1.SearchIndex=DVD& ItemSearch.2.Keywords=teaching%20Lily%20various%20computer%20related%20skills& ItemSearch.2.SearchIndex=Blended& ItemSearch.Shared.Availability=Available& ItemSearch.Shared.Condition=All& ItemSearch.Shared.ResponseGroup=Small%2CSalesRank%2CImages%2COfferSummary%2CSimilarities& Operation=ItemSearch%2CSimilarityLookup& Service=AWSECommerceService& SimilarityLookup.1.ItemId=B000FNNHZ2& SimilarityLookup.2.ItemId=B000EQ5UPU& SimilarityLookup.Shared.Availability=Available& SimilarityLookup.Shared.Condition=All& SimilarityLookup.Shared.MerchantId=Amazon& SimilarityLookup.Shared.ResponseGroup=Small%2CSalesRank%2CImages%2COfferSummary& Timestamp=2010-04-02T17%3A18%3A05Z& Signature=---------------- Any ideas as to what I'm doing wrong?

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  • Using an HTML Textbox in place of an ASP.NET TextBox

    - by Velika
    If I add this to the ASPX page: <input id="Text1" type="text" value="Text1Value" /> I would expect to see "Text1" in the list of Request Form keys even WITHOUT setting the runat=Server property. ? request.Form.AllKeys I realize that if I do set that propery, then I will have a server-sided HTML control that I can reference using the name "Text1," but shouldn't I be able to access the text in the text box using the following VB.NET syntax? request.Form("Text1")

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  • The server rejected the session-establishment request: WCF hosted on IIS

    - by Dave Hanna
    Background: I'm working on a project where we have about a dozen distinct WCF services implemented in an IIS application, communicating over net.tcp on the default port (808), using the Microsoft Net.Tcp Port Sharing Service. I recently added a self-test method to the base class of each of these services so that I could remotely hit the service and get back a status string verifying that it was in operation. We implement this app in a ladder of environments - Development, QA, UAT, and finally production. My problem: My test program, which instantiates a connection to each service in turn and invokes the self-test method, works fine on all the environments below production. We recently moved the app to production, and I'm getting a weird error that I can't explain: On the first of the services that I hit, I get back an exception: "The server at [URL] rejected the session-establishment request". All the other services respond fine. I initially thought there was something wrong with the particular service that was failing, but I tried rearranging the list of services into a different order, and it SEEMS to always be the first service that I hit that fails. (I say SEEMS because it think once in the early iterations of testing, I saw it happen on the second service that it hit. But I haven't been able to reproduce that.) I've looked at application startup delays, and that doesn't seem to be the problem, because I can come back and run the test again as soon as it finishes - a delay of only a minute or two - and get the same error. Also, in the lower level environments, there is a start up delay of probably 30 seconds to a minute, but the result still comes back as expected. I've tried accessing the services over http from INetManager, and I get intermittent failures on all the services - a particular service will return a yellow screen of death on on invocation, then come up with the expected link to the WSDL on the next one seconds later. I'm completely at a loss to explain this behavior, or how to resolve it. I've googled the error message, and not found anything helpful. It may be a configuration issue - the production servers are newly provisioned VM's, and we may not have the config exactly right (whereas all the lower level environments have been running this and other similar apps for some time), but I have not idea what to look for. I've looked at the properties of the app pool that the app is running on and compared it to the lower level environments without finding any differences. If somebody can point me in the right direction, you would have my undying gratitude.

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  • tomcat5 HTTP 400 BAd Request

    - by Oneiroi
    OS is centOS 5.5 x64, rpm's are as follows: tomcat5-jsp-2.0-api-5.5.23-0jpp.9.el5_5 tomcat5-common-lib-5.5.23-0jpp.9.el5_5 tomcat5-servlet-2.4-api-5.5.23-0jpp.9.el5_5 tomcat5-server-lib-5.5.23-0jpp.9.el5_5 tomcat5-5.5.23-0jpp.9.el5_5 tomcat5-jasper-5.5.23-0jpp.9.el5_5 telnet localhost 8080 Trying 127.0.0.1... Connected to localhost.localdomain (127.0.0.1). Escape character is '^]'. GET / HTTP/1.0 Host: localhost HTTP/1.1 400 Bad Request Server: Apache-Coyote/1.1 Date: Thu, 16 Sep 2010 15:06:21 GMT Connection: close alternatives --display java output: alternatives --display java java - status is manual. link currently points to /usr/lib/jvm/jre1.6.0_21/bin/java /usr/lib/jvm/jre-1.6.0-openjdk.x86_64/bin/java - priority 16000 slave keytool: /usr/lib/jvm/jre-1.6.0-openjdk.x86_64/bin/keytool slave orbd: /usr/lib/jvm/jre-1.6.0-openjdk.x86_64/bin/orbd slave pack200: /usr/lib/jvm/jre-1.6.0-openjdk.x86_64/bin/pack200 slave rmid: /usr/lib/jvm/jre-1.6.0-openjdk.x86_64/bin/rmid slave rmiregistry: /usr/lib/jvm/jre-1.6.0-openjdk.x86_64/bin/rmiregistry slave servertool: /usr/lib/jvm/jre-1.6.0-openjdk.x86_64/bin/servertool slave tnameserv: /usr/lib/jvm/jre-1.6.0-openjdk.x86_64/bin/tnameserv slave unpack200: /usr/lib/jvm/jre-1.6.0-openjdk.x86_64/bin/unpack200 slave jre_exports: /usr/lib/jvm-exports/jre-1.6.0-openjdk.x86_64 slave jre: /usr/lib/jvm/jre-1.6.0-openjdk.x86_64 slave java.1.gz: /usr/share/man/man1/java-java-1.6.0-openjdk.1.gz slave keytool.1.gz: /usr/share/man/man1/keytool-java-1.6.0-openjdk.1.gz slave orbd.1.gz: /usr/share/man/man1/orbd-java-1.6.0-openjdk.1.gz slave pack200.1.gz: /usr/share/man/man1/pack200-java-1.6.0-openjdk.1.gz slave rmid.1.gz: /usr/share/man/man1/rmid-java-1.6.0-openjdk.1.gz slave rmiregistry.1.gz: /usr/share/man/man1/rmiregistry-java-1.6.0-openjdk.1.gz slave servertool.1.gz: /usr/share/man/man1/servertool-java-1.6.0-openjdk.1.gz slave tnameserv.1.gz: /usr/share/man/man1/tnameserv-java-1.6.0-openjdk.1.gz slave unpack200.1.gz: /usr/share/man/man1/unpack200-java-1.6.0-openjdk.1.gz /usr/lib/jvm/jre-1.4.2-gcj/bin/java - priority 1420 slave keytool: /usr/lib/jvm/jre-1.4.2-gcj/bin/keytool slave orbd: (null) slave pack200: (null) slave rmid: (null) slave rmiregistry: /usr/lib/jvm/jre-1.4.2-gcj/bin/rmiregistry slave servertool: (null) slave tnameserv: (null) slave unpack200: (null) slave jre_exports: /usr/lib/jvm-exports/jre-1.4.2-gcj slave jre: /usr/lib/jvm/jre-1.4.2-gcj slave java.1.gz: (null) slave keytool.1.gz: (null) slave orbd.1.gz: (null) slave pack200.1.gz: (null) slave rmid.1.gz: (null) slave rmiregistry.1.gz: (null) slave servertool.1.gz: (null) slave tnameserv.1.gz: (null) slave unpack200.1.gz: (null) /usr/lib/jvm/jre1.6.0_21/bin/java - priority 2 slave keytool: (null) slave orbd: (null) slave pack200: (null) slave rmid: (null) slave rmiregistry: (null) slave servertool: (null) slave tnameserv: (null) slave unpack200: (null) slave jre_exports: (null) slave jre: (null) slave java.1.gz: (null) slave keytool.1.gz: (null) slave orbd.1.gz: (null) slave pack200.1.gz: (null) slave rmid.1.gz: (null) slave rmiregistry.1.gz: (null) slave servertool.1.gz: (null) slave tnameserv.1.gz: (null) slave unpack200.1.gz: (null) Current `best' version is /usr/lib/jvm/jre-1.6.0-openjdk.x86_64/bin/java. Same occurs trying HTTP/1.1, and I am at a complete loss as to why.

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  • Exporting/Importing events to Outlook 2007 calendar - problem

    - by iandisme
    I work on a web app that involves scheduling. A user can view his schedule, and then download a meeting request file for a particular event. In Outlook 2003, simply opening this event would cause a meeting request to pop up and the user could accept, which would either add or update the event in their calendar. However, in Outlook 2007, the meeting request Accept function is disabled, and the reason given is that the user is the organizer and can't accept his own event request. The ICS file clearly shows that this is not the case. Has anyone experienced this same problem? Does anyone know how to work around it? (Using Outlook's import function is scarcely an option because it causes duplicate events to be created; the import function doesn't seem to care that the events have the same UID) Here is the ICS file: BEGIN:VCALENDAR PRODID:#{my app} VERSION:2.0 CALSCALE:GREGORIAN METHOD:REQUEST BEGIN:VEVENT DTSTAMP:20100324T150236Z UID:eeb639a1-f8e5-4eab-ab3c-232ad91364c6 SEQUENCE:2 ORGANIZER:#{myApp}.#{myDomain}.com DESCRIPTION: DTSTART;TZID=Europe/London:20110620T120010 DTEND;TZID=Europe/London:20110620T133010 SUMMARY:BREAK:Breakfast LOCATION:Room 101 END:VEVENT BEGIN:VTIMEZONE //Timezone info edited for brevity END:VTIMEZONE END:VCALENDAR

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  • Windows Azure Worldwide availability

    - by Insomniac
    Hi, I've been reviewing Windows Azure platform for some time, and can't find answer to one very important question. If I deploy my application within a cloud, how it will be reached from different places worldwide? For example if I have a web application with a database and want it to be accessible to users in UK, US, China and etc. Can I be sure that any user in the world will get almost the same request processing time? I think of it this way. 1. User sends request (navigates in browser to my web site) 2. This request gets in a cloud in a nearest location (closest to user MS Data Center?) 3. It is processed by an instance of my web application (in nearest location, with request to my centralized DB which can be far away but SQL request goes via MS internal network, which I believe should be very fast). 4. Response sent to user. Please let me know if I'm wrong. Thanks.

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  • Objective-C As A First OOP Language?

    - by Daniel Scocco
    I am just finishing the second semester of my CS degree. So far I learned C, all the fundamental algorithms and data structures (e.g., searching, sorting, linked lists, heaps, hash tables, trees, graphs, etc). Next year we'll start with OOP, using either Java or C++. Recently I got some ideas for some iPhone apps and got itchy to start working on them. However I heard some bad things about Objectice-C in the past, so I am wondering if learning it as my first OOP language could be a problem. Not to mention that I think it will be hard to find books/online courses that teach basic OOP concepts using Objective-C to illustrate the concepts (as opposed to books using Java or C++, which are plenty), so this could be another problem. In summary: should I start learning Objective-C and OOP concepts right now by my own, or wait one more semester until I learn Java/C++ at university and then jump into Objective-C? Update: For those interested in getting started with OOP via Objective-C I just found some nice tutorials inside Apple's Developer Library - http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/OOP_ObjC/Introduction/Introduction.html

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  • What Functional features are worth a little OOP confusion for the benefits they bring?

    - by bonomo
    After learning functional programming in Haskell and F#, the OOP paradigm seems ass-backwards with classes, interfaces, objects. Which aspects of FP can I bring to work that my co-workers can understand? Are any FP styles worth talking to my boss about retraining my team so that we can use them? Possible aspects of FP: Immutability Partial Application and Currying First Class Functions (function pointers / Functional Objects / Strategy Pattern) Lazy Evaluation (and Monads) Pure Functions (no side effects) Expressions (vs. Statements - each line of code produces a value instead of, or in addition to causing side effects) Recursion Pattern Matching Is it a free-for-all where we can do whatever the programming language supports to the limit that language supports it? Or is there a better guideline?

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  • How to structure classes in the filesystem?

    - by da_b0uncer
    I have a few (view) classes. Table, Tree, PagingColumn, SelectionColumn, SparkLineColumn, TimeColumn. currently they're flat under app/view like this: app/view/Table app/view/Tree app/view/PagingColumn ... I thought about restructuring it, because the Trees and Tables use the columns, but there are some columns, which only work in a tree, some who work in trees and tables and in the future there are probably some who only work in tables, I don't know. My first idea was like this: app/view/Table app/view/Tree app/view/column/PagingColumn app/view/column/SelectionColumn app/view/column/SparkLineColumn app/view/column/TimeColumn But since the SelectionColumn is explicitly for trees, I have the fear that future developers could get the idea of missuse them. But how to restructure it probably? Like this: app/view/table/panel/Table app/view/tree/panel/Tree app/view/tree/column/PagingColumn app/view/tree/column/SelectionColumn app/view/column/SparkLineColumn app/view/column/TimeColumn Or like this: app/view/Table app/view/Tree app/view/column/SparkLineColumn app/view/column/TimeColumn app/view/column/tree/PagingColumn app/view/column/tree/SelectionColumn

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  • RequestValidation Changes in ASP.NET 4.0

    - by Rick Strahl
    There’s been a change in the way the ValidateRequest attribute on WebForms works in ASP.NET 4.0. I noticed this today while updating a post on my WebLog all of which contain raw HTML and so all pretty much trigger request validation. I recently upgraded this app from ASP.NET 2.0 to 4.0 and it’s now failing to update posts. At first this was difficult to track down because of custom error handling in my app – the custom error handler traps the exception and logs it with only basic error information so the full detail of the error was initially hidden. After some more experimentation in development mode the error that occurs is the typical ASP.NET validate request error (‘A potentially dangerous Request.Form value was detetected…’) which looks like this in ASP.NET 4.0: At first when I got this I was real perplexed as I didn’t read the entire error message and because my page does have: <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="NewEntry.aspx.cs" Inherits="Westwind.WebLog.NewEntry" MasterPageFile="~/App_Templates/Standard/AdminMaster.master" ValidateRequest="false" EnableEventValidation="false" EnableViewState="false" %> WTF? ValidateRequest would seem like it should be enough, but alas in ASP.NET 4.0 apparently that setting alone is no longer enough. Reading the fine print in the error explains that you need to explicitly set the requestValidationMode for the application back to V2.0 in web.config: <httpRuntime executionTimeout="300" requestValidationMode="2.0" /> Kudos for the ASP.NET team for putting up a nice error message that tells me how to fix this problem, but excuse me why the heck would you change this behavior to require an explicit override to an optional and by default disabled page level switch? You’ve just made a relatively simple fix to a solution a nasty morass of hard to discover configuration settings??? The original way this worked was perfectly discoverable via attributes in the page. Now you can set this setting in the page and get completely unexpected behavior and you are required to set what effectively amounts to a backwards compatibility flag in the configuration file. It turns out the real reason for the .config flag is that the request validation behavior has moved from WebForms pipeline down into the entire ASP.NET/IIS request pipeline and is now applied against all requests. Here’s what the breaking changes page from Microsoft says about it: The request validation feature in ASP.NET provides a certain level of default protection against cross-site scripting (XSS) attacks. In previous versions of ASP.NET, request validation was enabled by default. However, it applied only to ASP.NET pages (.aspx files and their class files) and only when those pages were executing. In ASP.NET 4, by default, request validation is enabled for all requests, because it is enabled before the BeginRequest phase of an HTTP request. As a result, request validation applies to requests for all ASP.NET resources, not just .aspx page requests. This includes requests such as Web service calls and custom HTTP handlers. Request validation is also active when custom HTTP modules are reading the contents of an HTTP request. As a result, request validation errors might now occur for requests that previously did not trigger errors. To revert to the behavior of the ASP.NET 2.0 request validation feature, add the following setting in the Web.config file: <httpRuntime requestValidationMode="2.0" /> However, we recommend that you analyze any request validation errors to determine whether existing handlers, modules, or other custom code accesses potentially unsafe HTTP inputs that could be XSS attack vectors. Ok, so ValidateRequest of the form still works as it always has but it’s actually the ASP.NET Event Pipeline, not WebForms that’s throwing the above exception as request validation is applied to every request that hits the pipeline. Creating the runtime override removes the HttpRuntime checking and restores the WebForms only behavior. That fixes my immediate problem but still leaves me wondering especially given the vague wording of the above explanation. One thing that’s missing in the description is above is one important detail: The request validation is applied only to application/x-www-form-urlencoded POST content not to all inbound POST data. When I first read this this freaked me out because it sounds like literally ANY request hitting the pipeline is affected. To make sure this is not really so I created a quick handler: public class Handler1 : IHttpHandler { public void ProcessRequest(HttpContext context) { context.Response.ContentType = "text/plain"; context.Response.Write("Hello World <hr>" + context.Request.Form.ToString()); } public bool IsReusable { get { return false; } } } and called it with Fiddler by posting some XML to the handler using a default form-urlencoded POST content type: and sure enough – hitting the handler also causes the request validation error and 500 server response. Changing the content type to text/xml effectively fixes the problem however, bypassing the request validation filter so Web Services/AJAX handlers and custom modules/handlers that implement custom protocols aren’t affected as long as they work with special input content types. It also looks that multipart encoding does not trigger event validation of the runtime either so this request also works fine: POST http://rasnote/weblog/handler1.ashx HTTP/1.1 Content-Type: multipart/form-data; boundary=------7cf2a327f01ae User-Agent: West Wind Internet Protocols 5.53 Host: rasnote Content-Length: 40 Pragma: no-cache <xml>asdasd</xml>--------7cf2a327f01ae *That* probably should trigger event validation – since it is a potential HTML form submission, but it doesn’t. New Runtime Feature, Global Scope Only? Ok, so request validation is now a runtime feature but sadly it’s a feature that’s scoped to the ASP.NET Runtime – effective scope to the entire running application/app domain. You can still manually force validation using Request.ValidateInput() which gives you the option to do this in code, but that realistically will only work with the requestValidationMode set to V2.0 as well since the 4.0 mode auto-fires before code ever gets a chance to intercept the call. Given all that, the new setting in ASP.NET 4.0 seems to limit options and makes things more difficult and less flexible. Of course Microsoft gets to say ASP.NET is more secure by default because of it but what good is that if you have to turn off this flag the very first time you need to allow one single request that bypasses request validation??? This is really shortsighted design… <sigh>© Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET  

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  • Secure an Application/Software by expiration with Date?

    - by JNL
    I have been working on some software application and I update them every 6 months. Currently, the way I track the date is by extracting the date from the system when the user installes the application, encrypt it and store it in a file locally. Whenever the application is started, it checks if 6 months have passed, then it works or it doesn't, in which case it shows an error message telling the user to update. I wonder whether there is a better way to do this. Any comments or suggestions would be highly appreciated

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  • Refactoring in domain driven design

    - by Andrew Whitaker
    I've just started working on a project and we're using domain-driven design (as defined by Eric Evans in Domain-Driven Design: Tackling Complexity in the Heart of Software. I believe that our project is certainly a candidate for this design pattern as Evans describes it in his book. I'm struggling with the idea of constantly refactoring. I know refactoring is a necessity in any project and will happen inevitably as the software changes. However, in my experience, refactoring occurs when the needs of the development team change, not as understanding of the domain changes ("refactoring to greater insight" as Evans calls it). I'm most concerned with breakthroughs in understanding of the domain model. I understand making small changes, but what if a large change in the model is necessary? What's an effective way of convincing yourself (and others) you should refactor after you obtain a clearer domain model? After all, refactoring to improve code organization or performance could be completely separate from how expressive in terms of the ubiquitous language code is. Sometimes it just seems like there's not enough time to refactor. Luckily, SCRUM lends it self to refactoring. The iterative nature of SCRUM makes it easy to build a small piece and change and it. But over time that piece will get larger and what if you have a breakthrough after that piece is so large that it will be too difficult to change? Has anyone worked on a project employing domain-driven design? If so, it would be great to get some insight on this one. I'd especially like to hear some success stories, since DDD seems very difficult to get right. Thanks!

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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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  • Explanation needed, for “Ask, don't tell” approach?

    - by the_naive
    I'm taking a course on design patterns in software engineering and here I'm trying to understand the good and the bad way of design relating to "coupling" and "cohesion". I could not understand the concept described in the following image. The example of code shown in the image is ambiguous to me, so I can't quite clearly get what exactly "Ask, don't tell!" approach mean. Could you please explain?

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  • NoSQL is not about object databases

    NoSQL as a movement is an interesting beast. I kinda like that its negatively defined (I happen to belong myself to at least one other such a-community). Its not in its roots about proposing one specific new silver bullet to kill an old problem. its about challenging the consensus. Actually, blindly and systematically replacing relational databases with object databases would just replace one set of issues with another. No, the point is to recognize that relational databases are not a universal...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Collision filtering by object, team

    - by Bill Zimmerman
    Hi, I am looking for a good method to determine which objects will be considered for collision with other objects. My current idea is that each object has the following properties: alwaysCollidesWith = [list of objects that will always trigger a collision check] neverCollidesWith = [lost of objects that will never be considered] teamCollidesWith = [list of objects that will be checked, provided they belong to a different team] For example: -projectiles never have to be checked for collisions with other projectiles -players are always checked for collisions with players, regardless of team -projectiles are only considered for collisions if they collide with another teams players Does anyone see any weaknesses with this approach? Can anyone recommend a better approach?

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  • Triggering custom events in AJAX callbacks

    - by Sabrina Gelbart
    I'm pretty new to JavaScript, but one of the things that's been frustrating is that our AJAX callbacks have been getting packed with different functionality, making it difficult to keep everything separated and organized. I'm really new to programming, I have a feeling learning MVC a bit more would help me, but for now using custom events seems like it could help me keep my code a lot cleaner and prevent some problems. Here's what I'm talking about: function myAjaxFunction(){ $.post('ajax/test.html', function(data) { $(document).trigger('testDataLoaded',data); }); } function myOtherFunctionThatsDependentUponAjax(){ $(document).one('testDataLoaded', function(data){ alert (data); } } I also don't know if it's ok that I'm triggering document or not... Are there any patterns that look like this that I can read more about? What are the potential problems with this?

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  • Using JDialog with Tabbed Pane to draw different pictures [migrated]

    - by Bryam Ulloa
    I am using NetBeans, and I have a class that extends to JDialog, inside that Dialog box I have created a Tabbed Pane. The Tabbed Pane contains 6 different tabs, with 6 different panels of course. What I want to do is when I click on the different tabs, a diagram is supposed to be drawn with the paint method. My question is how can I draw on the different panels with just one paint method in another class being called from the Dialog class? Here is my code for the Dialog class: package GUI; public class NewJDialog extends javax.swing.JDialog{ /** * Creates new form NewJDialog */ public NewJDialog(java.awt.Frame parent, boolean modal) { super(parent, modal); initComponents(); } /** * This method is called from within the constructor to initialize the form. * WARNING: Do NOT modify this code. The content of this method is always * regenerated by the Form Editor. */ @SuppressWarnings("unchecked") // <editor-fold defaultstate="collapsed" desc="Generated Code"> private void initComponents() { jTabbedPane1 = new javax.swing.JTabbedPane(); jPanel1 = new javax.swing.JPanel(); jPanel2 = new javax.swing.JPanel(); jPanel3 = new javax.swing.JPanel(); jPanel4 = new javax.swing.JPanel(); jPanel5 = new javax.swing.JPanel(); jPanel6 = new javax.swing.JPanel(); jPanel7 = new javax.swing.JPanel(); jLabel1 = new javax.swing.JLabel(); jLabel2 = new javax.swing.JLabel(); setDefaultCloseOperation(javax.swing.WindowConstants.DISPOSE_ON_CLOSE); javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1); jPanel1.setLayout(jPanel1Layout); jPanel1Layout.setHorizontalGroup( jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGap(0, 466, Short.MAX_VALUE) ); jPanel1Layout.setVerticalGroup( jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGap(0, 242, Short.MAX_VALUE) ); jTabbedPane1.addTab("FCFS", jPanel1); javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2); jPanel2.setLayout(jPanel2Layout); jPanel2Layout.setHorizontalGroup( jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGap(0, 466, Short.MAX_VALUE) ); jPanel2Layout.setVerticalGroup( jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGap(0, 242, Short.MAX_VALUE) ); jTabbedPane1.addTab("SSTF", jPanel2); javax.swing.GroupLayout jPanel3Layout = new javax.swing.GroupLayout(jPanel3); jPanel3.setLayout(jPanel3Layout); jPanel3Layout.setHorizontalGroup( jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGap(0, 466, Short.MAX_VALUE) ); jPanel3Layout.setVerticalGroup( jPanel3Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGap(0, 242, Short.MAX_VALUE) ); jTabbedPane1.addTab("LOOK", jPanel3); javax.swing.GroupLayout jPanel4Layout = new javax.swing.GroupLayout(jPanel4); jPanel4.setLayout(jPanel4Layout); jPanel4Layout.setHorizontalGroup( jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGap(0, 466, Short.MAX_VALUE) ); jPanel4Layout.setVerticalGroup( jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGap(0, 242, Short.MAX_VALUE) ); jTabbedPane1.addTab("LOOK C", jPanel4); javax.swing.GroupLayout jPanel5Layout = new javax.swing.GroupLayout(jPanel5); jPanel5.setLayout(jPanel5Layout); jPanel5Layout.setHorizontalGroup( jPanel5Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGap(0, 466, Short.MAX_VALUE) ); jPanel5Layout.setVerticalGroup( jPanel5Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGap(0, 242, Short.MAX_VALUE) ); jTabbedPane1.addTab("SCAN", jPanel5); javax.swing.GroupLayout jPanel6Layout = new javax.swing.GroupLayout(jPanel6); jPanel6.setLayout(jPanel6Layout); jPanel6Layout.setHorizontalGroup( jPanel6Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGap(0, 466, Short.MAX_VALUE) ); jPanel6Layout.setVerticalGroup( jPanel6Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGap(0, 242, Short.MAX_VALUE) ); jTabbedPane1.addTab("SCAN C", jPanel6); getContentPane().add(jTabbedPane1, java.awt.BorderLayout.CENTER); jLabel1.setText("Distancia:"); jLabel2.setText("___________"); javax.swing.GroupLayout jPanel7Layout = new javax.swing.GroupLayout(jPanel7); jPanel7.setLayout(jPanel7Layout); jPanel7Layout.setHorizontalGroup( jPanel7Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGroup(jPanel7Layout.createSequentialGroup() .addGap(21, 21, 21) .addComponent(jLabel1) .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED) .addComponent(jLabel2) .addContainerGap(331, Short.MAX_VALUE)) ); jPanel7Layout.setVerticalGroup( jPanel7Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGroup(jPanel7Layout.createSequentialGroup() .addContainerGap() .addGroup(jPanel7Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) .addComponent(jLabel1) .addComponent(jLabel2)) .addContainerGap(15, Short.MAX_VALUE)) ); getContentPane().add(jPanel7, java.awt.BorderLayout.PAGE_START); pack(); }// </editor-fold> /** * @param args the command line arguments */ public static void main(String args[]) { /* Set the Nimbus look and feel */ //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) "> /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel. * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html */ try { for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) { if ("Nimbus".equals(info.getName())) { javax.swing.UIManager.setLookAndFeel(info.getClassName()); break; } } } catch (ClassNotFoundException ex) { java.util.logging.Logger.getLogger(NewJDialog.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); } catch (InstantiationException ex) { java.util.logging.Logger.getLogger(NewJDialog.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); } catch (IllegalAccessException ex) { java.util.logging.Logger.getLogger(NewJDialog.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); } catch (javax.swing.UnsupportedLookAndFeelException ex) { java.util.logging.Logger.getLogger(NewJDialog.class.getName()).log(java.util.logging.Level.SEVERE, null, ex); } //</editor-fold> /* Create and display the dialog */ java.awt.EventQueue.invokeLater(new Runnable() { public void run() { NewJDialog dialog = new NewJDialog(new javax.swing.JFrame(), true); dialog.addWindowListener(new java.awt.event.WindowAdapter() { @Override public void windowClosing(java.awt.event.WindowEvent e) { System.exit(0); } }); dialog.setVisible(true); } }); } // Variables declaration - do not modify private javax.swing.JLabel jLabel1; private javax.swing.JLabel jLabel2; private javax.swing.JPanel jPanel1; private javax.swing.JPanel jPanel2; private javax.swing.JPanel jPanel3; private javax.swing.JPanel jPanel4; private javax.swing.JPanel jPanel5; private javax.swing.JPanel jPanel6; private javax.swing.JPanel jPanel7; private javax.swing.JTabbedPane jTabbedPane1; // End of variables declaration } This is another class that I have created for the paint method: package GUI; import java.awt.Graphics; import javax.swing.JPanel; /** * * @author TOSHIBA */ public class Lienzo { private int width = 5; private int height = 5; private int y = 5; private int x = 0; private int x1 = 0; public Graphics Draw(Graphics g, int[] pistas) { //Im not sure if this is the correct way to do it //The diagram gets drawn according to values from an array //The array is not always the same thats why I used the different Panels for (int i = 0; i < pistas.length; i++) { x = pistas[i]; x1 = pistas[i + 1]; g.drawOval(x, y, width, height); g.drawString(Integer.toString(x), x, y); g.drawLine(x, y, x1, y); } return g; } } I hope you guys understand what I am trying to do with my program.

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  • When should method overloads be refactored?

    - by Ben Heley
    When should code that looks like: DoThing(string foo, string bar); DoThing(string foo, string bar, int baz, bool qux); ... DoThing(string foo, string bar, int baz, bool qux, string more, string andMore); Be refactored into something that can be called like so: var doThing = new DoThing(foo, bar); doThing.more = value; doThing.andMore = otherValue; doThing.Go(); Or should it be refactored into something else entirely? In the particular case that inspired this question, it's a public interface for an XSLT templating DLL where we've had to add various flags (of various types) that can't be embedded into the string XML input.

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  • design of 'game engine' for small javascript games?

    - by Matt Ball
    I'm making a group of two or three simple javascript games for fun. After someone finishes one game, they'll be presented with a harder or easier version of another game depending on whether the original game was won or lost. I have a high-level question about the design of things: So far I've created a class for one game type that manages the interaction with the UI and the state of the game itself. But for tracking how many of the subgames have been won, or for understanding whether the next game presented should be more or less difficult, are there arguments to be made for making a 'game engine' class? How does the engine communicate to the games? For instance, when a game is won, how is that information relayed to the engine? Is there a better or more common design? (If you want to see what I have so far, the games are slowly taking shape here: https://github.com/yosemitebandit/candela and can be viewed at http://yosemitebandit.com/candela)

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  • How to avoid general names for abstract classes?

    - by djechlin
    In general it's good to avoid words like "handle" or "process" as part of routine names and class names, unless you are dealing with (e.g.) file handles or (e.g.) unix processes. However abstract classes often don't really know what they're going to do with something besides, say, process it. In my current situation I have an "EmailProcessor" that logs into a user's inbox and processes messages from it. It's not really clear to me how to give this a more precise name, although I've noticed the following style matter arises: better to treat derived classes as clients and named the base class by the part of the functionality it implements? Gives it more meaning but will violate is-a. E.g. EmailAcquirer would be a reasonable name since it's acquiring for the derived class, but the derived class won't be acquiring for anyone. Or just really vague name since who knows what the derived classes will do. However "Processor" is still too general since it's doing many relevant operations, like logging in and using IMAP. Any way out of this dilemma? Problem is more evident for abstract methods, in which you can't really answer the question "what does this do?" because the answer is simply "whatever the client wants."

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  • Differentiate procedural language(c) from oop languages(c++)

    - by niko
    I have been trying to differentiate c and c++(or oop languages) but I don't understand where the difference is. Note I have never used c++ but I asked my friends and some of them to differentiate c and c++ They say c++ has oop concepts and also the public, private modes for definition of variables and which c does not have though. Seriously I have done vb.net programming for a while 2 to 3 months, I never faced a situation to use class concepts and modes of definition like public and private. So I thought what could be the use for these? My friend explained me a program saying that if a variable is public, it can be accessed anywhere I said why not declare it as a global variable like in c? He did not get back to my question and he said if a variable is private it cannot be accessed by some other functions I said why not define it as a local variable, even these he was unable to answer. No matter where I read private variables cannot be accessed whereas public variables can be then why not make public as global and private as local whats the difference? whats the real use of public and private ? please don't say it can be used by everyone, I suppose why not we use some conditions and make the calls? I have heard people saying security reasons, a friend said if a function need to be accessed it should be inherited first. He explained saying that only admin should be able to have some rights and not all so that functions are made private and inherited only by the admin to use Then I said why not we use if condition if ( login == "admin") invoke the function he still did not answer these question. Please clear me with these things, I have done vb.net and vba and little c++ without using oop concepts because I never found their real use while I was writing the code, I'm a little afraid am I too back in oop concepts?

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  • Blender Object Appearing Gray when all Lights are Off

    - by celestialorb
    I have an issue with Blender where, when I turn my only light off (a sun lamp) and render the image my object appears gray rather than black (and thus, not appear to the camera). I can't figure out why this is happening. Here's what I just did in my scene: Added a new UV Sphere mesh (to make a total of two spheres), made it visible to the camera, turned off the sun lamp (by setting energy to 0), and rendered. The result I obtained is below. I discovered this when attempting to render the first sphere with a material/texture on it and it was too bright. The material on the spheres (which are different) are very basic, there's no emit, diffuse and specular are at default values. Could there be an issue with the way my camera is setup? Thanks in advance!

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  • Central Exception Handler

    - by J-unior
    Recently I've been thinking about a general ExceptionHandler, that I could initialize once in my app context and inject it everywhere. The idea that it will have quite simple interface with just public void handle(Exception ex), and then according to exception type it should decide what to do, maybe just log it, or show an alert message to the user, or maybe kill the whole app. The question is, what is the prettiest way to write such handler without lots of instanceofs? Unfortunately googling gives me only the default exception handler for RuntimeException that was introduced in Java 5. My first idea is to create an enum, that will have Class field for exception type and it will return the appropriate execution point, for example a concrete exception handler that also implements the interface public void handle(Exception ex), but with the required casting already.

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