stack based - Page 199 - Developer IT

Is there any limit to AIX 5.3 pipe size ?

- by snowflake

Hello, I'm in trouble while performing cat/tail/head operation on large files on Aix 5.3. When asking for a cat of several 1Go file redirected to another one: cat file1 file2 file3 > outputfile The outputfile is limited to 2Go (cat: output error and result file is 2147483647 bytes) Filesystem is jfs2. I successfully uploaded through ftp 10Go files on the filesystem without problem. I found nothing relevant in etc/security/limits: default: fsize = -1 core = 2097151 cpu = -1 data = 262144 rss = 65536 stack = 65536 nofiles = 20000 ulimit -a core file size (blocks) unlimited data seg size (kbytes) 245759 file size (blocks) unlimited max memory size (kbytes) unlimited open files 2000 pipe size (512 bytes) 64 stack size (kbytes) 32768 cpu time (seconds) unlimited max user processes 2048 virtual memory (kbytes) 278527 The problem does not occur on another AIX 5.3 server, I'm just looking for a different configuration that might be the source of the problem. /etc/security/limits on the server without the problem: default: fsize = -1 core = 2097151 cpu = -1 data = 262144 rss = 65536 stack = 65536 nofiles = 20000 ulimit -a on the server without the problem: core file size (blocks, -c) 1048575 data seg size (kbytes, -d) 131072 file size (blocks, -f) unlimited max memory size (kbytes, -m) 32768 open files (-n) 20000 pipe size (512 bytes, -p) 64 stack size (kbytes, -s) 32768 cpu time (seconds, -t) unlimited max user processes (-u) 262144 virtual memory (kbytes, -v) unlimited

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java.lang.OutOfMemoryError: unable to create new native thread

- by Brad

I consistently get this exception when trying to run my Junit tests on my mac: java.lang.OutOfMemoryError: unable to create new native thread at java.lang.Thread.start0(Native Method) at java.lang.Thread.start(Thread.java:658) at java.util.concurrent.ThreadPoolExecutor.addIfUnderMaximumPoolSize(ThreadPoolExecutor.java:727) at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:657) at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:92) at com.google.appengine.tools.development.ApiProxyLocalImpl$PrivilegedApiAction.run(ApiProxyLocalImpl.java:197) at com.google.appengine.tools.development.ApiProxyLocalImpl$PrivilegedApiAction.run(ApiProxyLocalImpl.java:184) at java.security.AccessController.doPrivileged(Native Method) at com.google.appengine.tools.development.ApiProxyLocalImpl.doAsyncCall(ApiProxyLocalImpl.java:172) at com.google.appengine.tools.development.ApiProxyLocalImpl.makeAsyncCall(ApiProxyLocalImpl.java:138) The same set of unit tests pass perfectly fine on ubuntu and windows. Some information about my system resources on the mac: $ ulimit -a core file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited file size (blocks, -f) unlimited max locked memory (kbytes, -l) unlimited max memory size (kbytes, -m) unlimited open files (-n) 1024 pipe size (512 bytes, -p) 1 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) 266 virtual memory (kbytes, -v) unlimited $ java -version java version "1.6.0_24" Java(TM) SE Runtime Environment (build 1.6.0_24-b07-334-10M3326) Java HotSpot(TM) 64-Bit Server VM (build 19.1-b02-334, mixed mode) The reason I dont think this is an application issue is because the same tests pass in different environments. I have tried setting heap to 1024m, 512m and setting the stack to 64k and 128k (and each of these combinations) with no luck. My open files was originally 256 and I have bumped this to 1024. I have been googling around for a bit and all posts say to decrease heap size and increase stack size but that doesnt seem to help. Anyone have anymore ideas? EDIT: Here are is some environment information on my ubuntu box: $ ulimit -a core file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited scheduling priority (-e) 20 file size (blocks, -f) unlimited pending signals (-i) 16382 max locked memory (kbytes, -l) 64 max memory size (kbytes, -m) unlimited open files (-n) 1024 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) unlimited virtual memory (kbytes, -v) unlimited file locks (-x) unlimited $ java -version java version "1.6.0_24" Java(TM) SE Runtime Environment (build 1.6.0_24-b07) Java HotSpot(TM) 64-Bit Server VM (build 19.1-b02, mixed mode)

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Orphan IBM JVM process

- by Nicholas Key

Hi people, I have this issue about orphan IBM JVM process being created in the process tree: For example: C:\Program Files\IBM\WebSphere\AppServer\bin>wsadmin -lang jython -f "C:\Hello.py" Hello.py has the simple implementation: import time i = 0 while (1): i = i + 1 print "Hello World " + str(i) time.sleep(3.0) My machine has such JVM information: C:\Program Files\WebSphere\java\bin>java -verbose:sizes -version -Xmca32K RAM class segment increment -Xmco128K ROM class segment increment -Xmns0K initial new space size -Xmnx0K maximum new space size -Xms4M initial memory size -Xmos4M initial old space size -Xmox1624995K maximum old space size -Xmx1624995K memory maximum -Xmr16K remembered set size -Xlp4K large page size available large page sizes: 4K 4M -Xmso256K operating system thread stack size -Xiss2K java thread stack initial size -Xssi16K java thread stack increment -Xss256K java thread stack maximum size java version "1.6.0" Java(TM) SE Runtime Environment (build pwi3260sr6ifix-20091015_01(SR6+152211+155930+156106)) IBM J9 VM (build 2.4, JRE 1.6.0 IBM J9 2.4 Windows Server 2003 x86-32 jvmwi3260sr6-20091001_43491 (JIT enabled, AOT enabled) J9VM - 20091001_043491 JIT - r9_20090902_1330ifx1 GC - 20090817_AA) JCL - 20091006_01 While the program is running, I tried to kill it and subsequently I found an orphan IBM JVM process in the process tree. Is there a way to fix this issue? Why is there an orphan process in the first place? Is there something wrong with my code? I really don't believe that my simplistic code is wrongly implemented. Any suggestions?

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How to determine the root cause of a system lockup on Ubuntu 8.04 LTS?

- by jdt141

I'm currently working a project that involves setting up a PC/104 stack and running Ubuntu 8.04 LTS. We need to use the PC/104 stack because its an embedded application - and we're required to use a DeviceNet peripheral card to communicate to other devices. (DeviceNet is just a protocol on top of CAN.) Anyway, the following hardware is on the stack: Kontron MOPSPM104 with a 1GHz Intel Celeron processor ConnectTech FlashDrive/104 4GB Industrial Temp (-40 to +85 C) Woodhead (Molex) PC104DVNIO DeviceNet card A run of the mill 104 power supply The Kontron Board offers two serial ports, one VGA out, and two USB ports. The DeviceNet card is an ISA card. Because of this (per the User's Guide for the Kontron Board), I have manually set the IRQs in the BIOS to be appropriately configured, and turned off ACPI in both the BIOS and passed the appropriate flag in GRUB. I've installed Ubuntu 8.04 desktop, 32 bit. The problem that I'm having is that, from time to time, the entire 104 stack locks up. This only seems to happen in two cases, both of which we're running GNOME. We have a custom application that uses the DeviceNet card, and the system will lock up, or (more frequently) when we're running Firefox and either surfing for some information or trying to test it - typically by streaming video from a IP-camera. The reason I ask this questions is I cannot determine the root cause of this lockup. The IRQs appear to correctly configured in the BIOS and as the Kernel sees them, and nothing is logged to dmesg. If you all could help me determine the root cause of this lockup, I would greatly appreciate it. Thanks.

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cygwin fork error

- by Techie Help

I have set up a new PC and installed cygwin on it. Its windows 7 pro. Whenever I try to build our application on it, I get the following error: 0 [main] sh 3472 child_info_fork::abort: can't commit memory for stack 0x28A000(90112), Win32 error 487 /bin/sh: fork: retry: Resource temporarily unavailable 0 [main] sh 3220 child_info_fork::abort: can't commit memory for stack 0x28A000(90112), Win32 error 487 /bin/sh: fork: retry: Resource temporarily unavailable 0 [main] sh 4896 child_info_fork::abort: can't commit memory for stack 0x28A000(90112), Win32 error 487 /bin/sh: fork: retry: Resource temporarily unavailable 0 [main] sh 4884 child_info_fork::abort: can't commit memory for stack 0x28A000(90112), Win32 error 487 It prints this few times and then dies. I have already done a lot of research on this problem. I have already uninstalled and installed cygwin more than 5 times. Done rebaseall everytime I installed it. Checked for possible BLODA, I had notron antivirus, which I have removed. As an aside, I tried posting this question to cygwin mailing list after subscribing to it. But my mail does not appear on the list. I suppose they want address to be munged and I have no clue how to do it. supposedly, they are treating it as a spam. Any idea how I can post to the mailing list there.

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Basics of Join Predicate Pushdown in Oracle

- by Maria Colgan

Happy New Year to all of our readers! We hope you all had a great holiday season. We start the new year by continuing our series on Optimizer transformations. This time it is the turn of Predicate Pushdown. I would like to thank Rafi Ahmed for the content of this blog.Normally, a view cannot be joined with an index-based nested loop (i.e., index access) join, since a view, in contrast with a base table, does not have an index defined on it. A view can only be joined with other tables using three methods: hash, nested loop, and sort-merge joins. Introduction The join predicate pushdown (JPPD) transformation allows a view to be joined with index-based nested-loop join method, which may provide a more optimal alternative. In the join predicate pushdown transformation, the view remains a separate query block, but it contains the join predicate, which is pushed down from its containing query block into the view. The view thus becomes correlated and must be evaluated for each row of the outer query block. These pushed-down join predicates, once inside the view, open up new index access paths on the base tables inside the view; this allows the view to be joined with index-based nested-loop join method, thereby enabling the optimizer to select an efficient execution plan. The join predicate pushdown transformation is not always optimal. The join predicate pushed-down view becomes correlated and it must be evaluated for each outer row; if there is a large number of outer rows, the cost of evaluating the view multiple times may make the nested-loop join suboptimal, and therefore joining the view with hash or sort-merge join method may be more efficient. The decision whether to push down join predicates into a view is determined by evaluating the costs of the outer query with and without the join predicate pushdown transformation under Oracle's cost-based query transformation framework. The join predicate pushdown transformation applies to both non-mergeable views and mergeable views and to pre-defined and inline views as well as to views generated internally by the optimizer during various transformations. The following shows the types of views on which join predicate pushdown is currently supported. UNION ALL/UNION view Outer-joined view Anti-joined view Semi-joined view DISTINCT view GROUP-BY view Examples Consider query A, which has an outer-joined view V. The view cannot be merged, as it contains two tables, and the join between these two tables must be performed before the join between the view and the outer table T4. A: SELECT T4.unique1, V.unique3 FROM T_4K T4, (SELECT T10.unique3, T10.hundred, T10.ten FROM T_5K T5, T_10K T10 WHERE T5.unique3 = T10.unique3) VWHERE T4.unique3 = V.hundred(+) AND T4.ten = V.ten(+) AND T4.thousand = 5; The following shows the non-default plan for query A generated by disabling join predicate pushdown. When query A undergoes join predicate pushdown, it yields query B. Note that query B is expressed in a non-standard SQL and shows an internal representation of the query. B: SELECT T4.unique1, V.unique3 FROM T_4K T4, (SELECT T10.unique3, T10.hundred, T10.ten FROM T_5K T5, T_10K T10 WHERE T5.unique3 = T10.unique3 AND T4.unique3 = V.hundred(+) AND T4.ten = V.ten(+)) V WHERE T4.thousand = 5; The execution plan for query B is shown below. In the execution plan BX, note the keyword 'VIEW PUSHED PREDICATE' indicates that the view has undergone the join predicate pushdown transformation. The join predicates (shown here in red) have been moved into the view V; these join predicates open up index access paths thereby enabling index-based nested-loop join of the view. With join predicate pushdown, the cost of query A has come down from 62 to 32. As mentioned earlier, the join predicate pushdown transformation is cost-based, and a join predicate pushed-down plan is selected only when it reduces the overall cost. Consider another example of a query C, which contains a view with the UNION ALL set operator.C: SELECT R.unique1, V.unique3 FROM T_5K R, (SELECT T1.unique3, T2.unique1+T1.unique1 FROM T_5K T1, T_10K T2 WHERE T1.unique1 = T2.unique1 UNION ALL SELECT T1.unique3, T2.unique2 FROM G_4K T1, T_10K T2 WHERE T1.unique1 = T2.unique1) V WHERE R.unique3 = V.unique3 and R.thousand < 1; The execution plan of query C is shown below. In the above, 'VIEW UNION ALL PUSHED PREDICATE' indicates that the UNION ALL view has undergone the join predicate pushdown transformation. As can be seen, here the join predicate has been replicated and pushed inside every branch of the UNION ALL view. The join predicates (shown here in red) open up index access paths thereby enabling index-based nested loop join of the view. Consider query D as an example of join predicate pushdown into a distinct view. We have the following cardinalities of the tables involved in query D: Sales (1,016,271), Customers (50,000), and Costs (787,766). D: SELECT C.cust_last_name, C.cust_city FROM customers C, (SELECT DISTINCT S.cust_id FROM sales S, costs CT WHERE S.prod_id = CT.prod_id and CT.unit_price > 70) V WHERE C.cust_state_province = 'CA' and C.cust_id = V.cust_id; The execution plan of query D is shown below. As shown in XD, when query D undergoes join predicate pushdown transformation, the expensive DISTINCT operator is removed and the join is converted into a semi-join; this is possible, since all the SELECT list items of the view participate in an equi-join with the outer tables. Under similar conditions, when a group-by view undergoes join predicate pushdown transformation, the expensive group-by operator can also be removed. With the join predicate pushdown transformation, the elapsed time of query D came down from 63 seconds to 5 seconds. Since distinct and group-by views are mergeable views, the cost-based transformation framework also compares the cost of merging the view with that of join predicate pushdown in selecting the most optimal execution plan. Summary We have tried to illustrate the basic ideas behind join predicate pushdown on different types of views by showing example queries that are quite simple. Oracle can handle far more complex queries and other types of views not shown here in the examples. Again many thanks to Rafi Ahmed for the content of this blog post.

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Security in Software

The term security has many meanings based on the context and perspective in which it is used. Security from the perspective of software/system development is the continuous process of maintaining confidentiality, integrity, and availability of a system, sub-system, and system data. This definition at a very high level can be restated as the following: Computer security is a continuous process dealing with confidentiality, integrity, and availability on multiple layers of a system. Key Aspects of Software Security Integrity Confidentiality Availability Integrity within a system is the concept of ensuring only authorized users can only manipulate information through authorized methods and procedures. An example of this can be seen in a simple lead management application. If the business decided to allow each sales member to only update their own leads in the system and sales managers can update all leads in the system then an integrity violation would occur if a sales member attempted to update someone else’s leads. An integrity violation occurs when a team member attempts to update someone else’s lead because it was not entered by the sales member. This violates the business rule that leads can only be update by the originating sales member. Confidentiality within a system is the concept of preventing unauthorized access to specific information or tools. In a perfect world the knowledge of the existence of confidential information/tools would be unknown to all those who do not have access. When this this concept is applied within the context of an application only the authorized information/tools will be available. If we look at the sales lead management system again, leads can only be updated by originating sales members. If we look at this rule then we can say that all sales leads are confidential between the system and the sales person who entered the lead in to the system. The other sales team members would not need to know about the leads let alone need to access it. Availability within a system is the concept of authorized users being able to access the system. A real world example can be seen again from the lead management system. If that system was hosted on a web server then IP restriction can be put in place to limit access to the system based on the requesting IP address. If in this example all of the sales members where accessing the system from the 192.168.1.23 IP address then removing access from all other IPs would be need to ensure that improper access to the system is prevented while approved users can access the system from an authorized location. In essence if the requesting user is not coming from an authorized IP address then the system will appear unavailable to them. This is one way of controlling where a system is accessed. Through the years several design principles have been identified as being beneficial when integrating security aspects into a system. These principles in various combinations allow for a system to achieve the previously defined aspects of security based on generic architectural models. Security Design Principles Least Privilege Fail-Safe Defaults Economy of Mechanism Complete Mediation Open Design Separation Privilege Least Common Mechanism Psychological Acceptability Defense in Depth Least Privilege Design PrincipleThe Least Privilege design principle requires a minimalistic approach to granting user access rights to specific information and tools. Additionally, access rights should be time based as to limit resources access bound to the time needed to complete necessary tasks. The implications of granting access beyond this scope will allow for unnecessary access and the potential for data to be updated out of the approved context. The assigning of access rights will limit system damaging attacks from users whether they are intentional or not. This principle attempts to limit data changes and prevents potential damage from occurring by accident or error by reducing the amount of potential interactions with a resource. Fail-Safe Defaults Design PrincipleThe Fail-Safe Defaults design principle pertains to allowing access to resources based on granted access over access exclusion. This principle is a methodology for allowing resources to be accessed only if explicit access is granted to a user. By default users do not have access to any resources until access has been granted. This approach prevents unauthorized users from gaining access to resource until access is given. Economy of Mechanism Design PrincipleThe Economy of mechanism design principle requires that systems should be designed as simple and small as possible. Design and implementation errors result in unauthorized access to resources that would not be noticed during normal use. Complete Mediation Design PrincipleThe Complete Mediation design principle states that every access to every resource must be validated for authorization. Open Design Design PrincipleThe Open Design Design Principle is a concept that the security of a system and its algorithms should not be dependent on secrecy of its design or implementation Separation Privilege Design PrincipleThe separation privilege design principle requires that all resource approved resource access attempts be granted based on more than a single condition. For example a user should be validated for active status and has access to the specific resource. Least Common Mechanism Design PrincipleThe Least Common Mechanism design principle declares that mechanisms used to access resources should not be shared. Psychological Acceptability Design PrincipleThe Psychological Acceptability design principle refers to security mechanisms not make resources more difficult to access than if the security mechanisms were not present Defense in Depth Design PrincipleThe Defense in Depth design principle is a concept of layering resource access authorization verification in a system reduces the chance of a successful attack. This layered approach to resource authorization requires unauthorized users to circumvent each authorization attempt to gain access to a resource. When designing a system that requires meeting a security quality attribute architects need consider the scope of security needs and the minimum required security qualities. Not every system will need to use all of the basic security design principles but will use one or more in combination based on a company’s and architect’s threshold for system security because the existence of security in an application adds an additional layer to the overall system and can affect performance. That is why the definition of minimum security acceptably is need when a system is design because this quality attributes needs to be factored in with the other system quality attributes so that the system in question adheres to all qualities based on the priorities of the qualities. Resources: Barnum, Sean. Gegick, Michael. (2005). Least Privilege. Retrieved on August 28, 2011 from https://buildsecurityin.us-cert.gov/bsi/articles/knowledge/principles/351-BSI.html Saltzer, Jerry. (2011). BASIC PRINCIPLES OF INFORMATION PROTECTION. Retrieved on August 28, 2011 from http://web.mit.edu/Saltzer/www/publications/protection/Basic.html Barnum, Sean. Gegick, Michael. (2005). Defense in Depth. Retrieved on August 28, 2011 from https://buildsecurityin.us-cert.gov/bsi/articles/knowledge/principles/347-BSI.html Bertino, Elisa. (2005). Design Principles for Security. Retrieved on August 28, 2011 from http://homes.cerias.purdue.edu/~bhargav/cs526/security-9.pdf

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WCF Publish/Subscribe and using callbacks to send data to specific users

- by manemawanna

Hello thanks for looking, I'm working on a project at the moment and have become a little stuck. I'm creating a client server app, which allows a client to subscribe to the server to have messages forwarded to it. The issue I'm having is that when the client subscribes I wish for them to only recieve updates that relate to them. The system basically passes messages from a SQL server DB which the server monitors. When a new message is recieved the server should only forward the message to the clients that it applys to, based on whos logged on the client machine. I've had a look and found code samples which sign up for messages to be broadcast across all clients who have subscribed, but not any that show how to identify individual clients and if messages apply to them. If anyone could help or point me in the right direction it would be appreciated. You can now find some of my code below: namespace AnnouncementServiceLibrary { [ServiceContract(CallbackContract = typeof(IMessageCallback))] public interface IMessageCheck { [OperationContract] void MessageCheck(); } } namespace AnnouncementServiceLibrary { public interface IMessageCallback { [OperationContract(IsOneWay = true)] void OnNewMessage(Mess message); } } public bool Subscribe() { try { IMessageCallback callback = OperationContext.Current.GetCallbackChannel<IMessageCallback>(); //If they dont already exist in the subscribers list, adds them to it if (!subscribers.Contains(callback)) subscribers.Add(callback); return true; } catch { //Otherwise if an error occurs returns false return false; } } Subscribe/Unsubscribe: private static readonly List<IMessageCallback> subscribers = new List<IMessageCallback>(); /// <summary> /// Unsubscribes the user from recieving new messages when they become avaliable /// </summary> /// <returns>Returns a bool that indicates whether the operation worked or not</returns> public bool Unsubscribe() { try { IMessageCallback callback = OperationContext.Current.GetCallbackChannel<IMessageCallback>(); //If they exist in the list of subscribers they are then removed if (subscribers.Contains(callback)) subscribers.Remove(callback); return true; } catch { //Otherwise if an error occurs returns false return false; } } Finally this at the moment isnt't working as basically when a user subscribes as it loops through I want it to filter based on the users userID: #region IMessageCheck Members /// <summary> /// This method checks for new messages recieved based on those who have subscribed for the service /// </summary> public void MessageCheck() { //A continuous loop to keep the method going while(true) { //Changes the thread to a sleep state for 2 mins? Thread.Sleep(200000); //Go through each subscriber based on there callback information subscribers.ForEach(delegate(IMessageCallback callback) { //Checks if the person who wanted the callback can still be communicated with if (((ICommunicationObject)callback).State == CommunicationState.Opened) { //Creates a link to the database and gets the required information List<Mess> mess = new List<Mess>(); List<Message> me; List<MessageLink> messLink; AnnouncementDBDataContext aDb = new AnnouncementDBDataContext(); me = aDb.Messages.ToList(); messLink = aDb.MessageLinks.ToList(); //Query to retrieve any messages which are newer than the time when the last cycle finished var result = (from a in messLink join b in me on a.UniqueID equals b.UniqueID where b.TimeRecieved > _time select new { b.UniqueID, b.Author, b.Title, b.Body, b.Priority, a.Read, b.TimeRecieved }); //Foreach result a new message is created and returned to the PC that subscribed foreach (var a in result) { Mess message = new Mess(a.UniqueID, a.Author, a.Title, a.Body, a.Priority, (bool)a.Read, a.TimeRecieved); callback.OnNewMessage(message); } } //If the requesting PC can't be contacted they are removed from the subscribers list else { subscribers.Remove(callback); } }); //Sets the datetime so the next cycle can measure against to see if new messages have been recieved _time = DateTime.Now; } } #endregion

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Modern Java alternatives

- by Ralph

I'm not sure if stackoverflow is the best forum for this discussion. I have been a Java developer for 14 years and have written an enterprise-level (~500,000 line) Swing application that uses most of the standard library APIs. Recently, I have become disappointed with the progress that the language has made to "modernize" itself, and am looking for an alternative for ongoing development. I have considered moving to the .NET platform, but I have issues with using something the only runs well in Windows (I know about Mono, but that is still far behind Microsoft). I also plan on buying a new Macbook Pro as soon as Apple releases their new rumored Arrandale-based machines and want to develop in an environment that will feel "at home" in Unix/Linux. I have considered using Python or Ruby, but the standard Java library is arguably the largest of any modern language. In JVM-based languages, I looked at Groovy, but am disappointed with its performance. Rumor has it that with the soon-to-be released JDK7, with its InvokeDynamic instruction, this will improve, but I don't know how much. Groovy is also not truly a functional language, although it provides closures and some of the "functional" features on collections. It does not embrace immutability. I have narrowed my search down to two JVM-based alternatives: Scala and Clojure. Each has its strengths and weaknesses. I am looking for the stackoverflow readerships' opinions. I am not an expert at either of these languages; I have read 2 1/2 books on Scala and am currently reading Stu Halloway's book on Clojure. Scala is strongly statically typed. I know the dynamic language folks claim that static typing is a crutch for not doing unit testing, but it does provide a mechanism for compile-time location of a whole class of errors. Scala is more concise than Java, but not as much as Clojure. Scala's inter-operation with Java seems to be better than Clojure's, in that most Java operations are easier to do in Scala than in Clojure. For example, I can find no way in Clojure to create a non-static initialization block in a class derived from a Java superclass. For example, I like the Apache commons CLI library for command line argument parsing. In Java and Scala, I can create a new Options object and add Option items to it in an initialization block as follows (Java code): final Options options = new Options() { { addOption(new Option("?", "help", false, "Show this usage information"); // other options } }; I can't figure out how to the same thing in Clojure (except by using (doit...)), although that may reflect my lack of knowledge of the language. Clojure's collections are optimized for immutability. They rarely require copy-on-write semantics. I don't know if Scala's immutable collections are implemented using similar algorithms, but Rich Hickey (Clojure's inventor) goes out of his way to explain how that language's data structures are efficient. Clojure was designed from the beginning for concurrency (as was Scala) and with modern multi-core processors, concurrency takes on more importance, but I occasionally need to write simple non-concurrent utilities, and Scala code probably runs a little faster for these applications since it discourages, but does not prohibit, "simple" mutability. One could argue that one-off utilities do not have to be super-fast, but sometimes they do tasks that take hours or days to complete. I know that there is no right answer to this "question", but I thought I would open it up for discussion. If anyone has a suggestion for another JVM-based language that can be used for enterprise level development, please list it. Also, it is not my intent to start a flame war. Thanks, Ralph

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Jquery getJSON cross domain problems

- by Charlie

I cant seem to get my JSON file to work when pulling it in from another domain using JQuerys getJSON. I have placed the callback part at the end of the url but still have no joy. Firebug tells me its a cross domain issue, which seems to make sense as if I place the json file locally the below code (excluding the ?jsoncallback=? works fine) Heres the Jquery part $.getJSON("http://anotherdomain/js/morearticles.js?jsoncallback=?", function(json){ if (show5More.nextSetCount ' + this.titletext + '' + this.paratext + '').appendTo("#lineupswitch"); } else { $('' + this.titletext + '' + this.paratext + '').appendTo("#lineupswitch"); } }); return false; } }); } }); } And the JSON, which I have validated. { "items": [ [ { "href": "/edinburgh/video/news-090415-s2-squalor-edinburgh/", "thumbimg": "http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_19721015001_asset-1239819553334.jpg?pubId=1486976045", "titletext": "Cannabis plants found in house with neglected children", "paratext": "A court has heard four young children lived in", "cname": "" }, { "href": "/edinburgh/video/news-090414-s2-waverley-station-edinburgh/", "thumbimg": "http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_19537855001_asset-1239732920496.jpg?pubId=1486976045", "titletext": "Multi-million pound revamp for Waverley Station", "paratext": "Edinburgh's Waverley Station is set for a", "cname": "" }, { "href": "/edinburgh/video/news-s2-natal-20090408/", "thumbimg":"http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_18948154001_asset-1239206353135.jpg?pubId=1486976045", "titletext": "Stillbirth charity on the road to raise awareness", "paratext": "SANDS Lothian are hoping to highlight their", "cname": "" }, { "href": "/edinburgh/video/news-090407-l2-rbs/", "thumbimg":"http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_18827378001_asset-1239110600777.jpg?pubId=1486976045", "titletext": "Thousands of jobs to go at Royal Bank of Scotland", "paratext": "Edinburgh-based bank to cut 4,500 positions in the", "cname": "" }, { "href": "/edinburgh/video/news-090415-s2-squalor-edinburgh/", "thumbimg": "http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_19721015001_asset-1239819553334.jpg?pubId=1486976045", "titletext": "1", "paratext": "A court has heard four young children lived in", "cname": "lastlineup" } ], [ { "href": "/edinburgh/video/news-090415-s2-squalor-edinburgh/", "thumbimg": "http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_19721015001_asset-1239819553334.jpg?pubId=1486976045", "titletext": "1", "paratext": "A court has heard four young children lived in", "cname": "" }, { "href": "/edinburgh/video/news-090414-s2-waverley-station-edinburgh/", "thumbimg": "http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_19537855001_asset-1239732920496.jpg?pubId=1486976045", "titletext": "2", "paratext": "Edinburgh's Waverley Station is set for a", "cname": "" }, { "href": "/edinburgh/video/news-s2-natal-20090408/", "thumbimg":"http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_18948154001_asset-1239206353135.jpg?pubId=1486976045", "titletext": "Stillbirth charity on the road to raise awareness", "paratext": "3", "cname": "" }, { "href": "/edinburgh/video/news-090407-l2-rbs/", "thumbimg":"http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_18827378001_asset-1239110600777.jpg?pubId=1486976045", "titletext": "Thousands of jobs to go at Royal Bank of Scotland", "paratext": "4", "cname": "" }, { "href": "/edinburgh/video/news-090407-l2-rbs/", "thumbimg":"http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_18827378001_asset-1239110600777.jpg?pubId=1486976045", "titletext": "Thousands of jobs to go at Royal Bank of Scotland", "paratext": "Edinburgh-based bank to cut 4,500 positions in the", "cname": "lastlineup" } ] ] } { "items": [ [ { "href": "/edinburgh/video/news-090415-s2-squalor-edinburgh/", "thumbimg": "http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_19721015001_asset-1239819553334.jpg?pubId=1486976045", "titletext": "Cannabis plants found in house with neglected children", "paratext": "A court has heard four young children lived in", "cname": "" }, { "href": "/edinburgh/video/news-090414-s2-waverley-station-edinburgh/", "thumbimg": "http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_19537855001_asset-1239732920496.jpg?pubId=1486976045", "titletext": "Multi-million pound revamp for Waverley Station", "paratext": "Edinburgh's Waverley Station is set for a", "cname": "" }, { "href": "/edinburgh/video/news-s2-natal-20090408/", "thumbimg":"http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_18948154001_asset-1239206353135.jpg?pubId=1486976045", "titletext": "Stillbirth charity on the road to raise awareness", "paratext": "SANDS Lothian are hoping to highlight their", "cname": "" }, { "href": "/edinburgh/video/news-090407-l2-rbs/", "thumbimg":"http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_18827378001_asset-1239110600777.jpg?pubId=1486976045", "titletext": "Thousands of jobs to go at Royal Bank of Scotland", "paratext": "Edinburgh-based bank to cut 4,500 positions in the", "cname": "" }, { "href": "/edinburgh/video/news-090415-s2-squalor-edinburgh/", "thumbimg": "http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_19721015001_asset-1239819553334.jpg?pubId=1486976045", "titletext": "1", "paratext": "A court has heard four young children lived in", "cname": "lastlineup" } ], [ { "href": "/edinburgh/video/news-090415-s2-squalor-edinburgh/", "thumbimg": "http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_19721015001_asset-1239819553334.jpg?pubId=1486976045", "titletext": "1", "paratext": "A court has heard four young children lived in", "cname": "" }, { "href": "/edinburgh/video/news-090414-s2-waverley-station-edinburgh/", "thumbimg": "http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_19537855001_asset-1239732920496.jpg?pubId=1486976045", "titletext": "2", "paratext": "Edinburgh's Waverley Station is set for a", "cname": "" }, { "href": "/edinburgh/video/news-s2-natal-20090408/", "thumbimg":"http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_18948154001_asset-1239206353135.jpg?pubId=1486976045", "titletext": "Stillbirth charity on the road to raise awareness", "paratext": "3", "cname": "" }, { "href": "/edinburgh/video/news-090407-l2-rbs/", "thumbimg":"http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_18827378001_asset-1239110600777.jpg?pubId=1486976045", "titletext": "Thousands of jobs to go at Royal Bank of Scotland", "paratext": "4", "cname": "" }, { "href": "/edinburgh/video/news-090407-l2-rbs/", "thumbimg":"http://brightcove.vo.llnwd.net/d7/unsecured/media/1486976045/1486976045_18827378001_asset-1239110600777.jpg?pubId=1486976045", "titletext": "Thousands of jobs to go at Royal Bank of Scotland", "paratext": "Edinburgh-based bank to cut 4,500 positions in the", "cname": "lastlineup" } ] ] }

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Modern alternatives to Java

- by Ralph

I have been a Java developer for 14 years and have written an enterprise-level (~500 kloc) Swing application that uses most of the standard library APIs. Recently, I have become disappointed with the progress that the language has made to "modernize" itself, and am looking for an alternative for ongoing development. I have considered moving to the .NET platform, but I have issues with using something the only runs well in Windows (I know about Mono, but that is still far behind Microsoft). I also plan on buying a new Macbook Pro as soon as Apple releases their new rumored Arrandale-based machines and want to develop in an environment that will feel "at home" in Unix/Linux. I have considered using Python or Ruby, but the standard Java library is arguably the largest of any modern language. In JVM-based languages, I looked at Groovy, but am disappointed with its performance. Rumor has it that with the soon-to-be released JDK7, with its InvokeDynamic instruction, this will improve, but I don't know how much. Groovy is also not truly a functional language, although it provides closures and some of the "functional" features on collections. It does not embrace immutability. I have narrowed my search down to two JVM-based alternatives: Scala and Clojure. Each has its strengths and weaknesses. I am looking for opinions. I am not an expert at either of these languages; I have read 2 1/2 books on Scala and am currently reading Stu Halloway's book on Clojure. Scala is strongly statically typed. I know the dynamic language folks claim that static typing is a crutch for not doing unit testing, but it does provide a mechanism for compile-time location of a whole class of errors. Scala is more concise than Java, but not as much as Clojure. Scala's inter-operation with Java seems to be better than Clojure's, in that most Java operations are easier to do in Scala than in Clojure. For example, I can find no way in Clojure to create a non-static initialization block in a class derived from a Java superclass. For example, I like the Apache commons CLI library for command line argument parsing. In Java and Scala, I can create a new Options object and add Option items to it in an initialization block as follows (Java code): final Options options = new Options() { { addOption(new Option("?", "help", false, "Show this usage information"); // other options } }; I can't figure out how to the same thing in Clojure (except by using (doit...)), although that may reflect my lack of knowledge of the language. Clojure's collections are optimized for immutability. They rarely require copy-on-write semantics. I don't know if Scala's immutable collections are implemented using similar algorithms, but Rich Hickey (Clojure's inventor) goes out of his way to explain how that language's data structures are efficient. Clojure was designed from the beginning for concurrency (as was Scala) and with modern multi-core processors, concurrency takes on more importance, but I occasionally need to write simple non-concurrent utilities, and Scala code probably runs a little faster for these applications since it discourages, but does not prohibit, "simple" mutability. One could argue that one-off utilities do not have to be super-fast, but sometimes they do tasks that take hours or days to complete. I know that there is no right answer to this "question", but I thought I would open it up for discussion. Are there other JVM-based languages that can be used for enterprise level development?

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Android - determine specific locations (X,Y coordinates) on a Bitmap on different resolutions?

- by Mike

My app that I am trying to create is a board game. It will have one bitmap as the board and pieces that will move to different locations on the board. The general design of the board is square, has a certain number of columns and rows and has a border for looks. Think of a chess board or scrabble board. Before using bitmaps, I first created the board and boarder by manually drawing it - drawLine & drawRect. I decided how many pixels in width the border would be based on the screen width and height passed in on "onSizeChanged". The remaining screen I divided by the number of columns or rows I needed. For examples sake, let's say the screen dimensions are 102 x 102. I may have chosen to set the border at 1 and set the number of rows & columns at 10. That would leave 100 x 100 left (reduced by two to account for the top & bottom border, as well as left/right border). Then with columns and rows set to 10, that would leave 10 pixels left for both height and width. No matter what screen size is passed in, I store exactly how many pixels in width the boarder is and the height & width of each square on the board. I know exactly what location on the screen to move the pieces to based on a simple formula and I know exactly what cell a user touched to make a move. Now how does that work with bitmaps? Meaning, if I create 3 different background bitmaps, once for each density, won't they still be resized to fit each devices screen resolution, because from what I read there were not just 3 screen resolutions, but 5 and now with tablets - even more. If I or Android scales the bitmaps up or down to fit the current devices screen size, how will I know how wide the border is scaled to and the dimensions of each square in order to figure out where to move a piece or calculate where a player touched. So far the examples I have looked at just show how to scale the overall bitmap and get the overall bitmaps width and height. But, I don't see how to tell how many pixels wide or tall each part of the board would be after it was scaled. When I draw each line and rectangle myself based in the screen dimensions from onSizeChanged, I always know these dimensions. If anyone has any sample code or a URL to point me to that I can a read about this with bitmaps, I would appreciate it. Thanks, --Mike BTW, here is some sample code (very simplified) on how I know the dimensions of my game board (border and squares) no matter the screen size. Now I just need to know how to do this with the board as a bitmap that gets scaled to any screen size. @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { intScreenWidth = w; intScreenHeight = h; // Set Border width - my real code changes this value based on the dimensions of w // and h that are passed in. In other words bigger screens get a slightly larger // border. intOuterBorder = 1; /** Reserve part of the board for the boardgame and part for player controls & score My real code forces this to be square, but this is good enough to get the point across. **/ floatBoardHeight = intScreenHeight / 4 * 3; // My real code actually causes floatCellWidth and floatCellHeight to // be equal (Square). floatCellWidth = (intScreenWidth - intOuterBorder * 2 ) / intNumColumns; floatCellHeight = (floatBoardHeight - intOuterBorder * 2) / intNumRows; super.onSizeChanged(w, h, oldw, oldh); }

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Passing a parameter using RelayCommand defined in the ViewModel (from Josh Smith example)

- by eesh

I would like to pass a parameter defined in the XAML (View) of my application to the ViewModel class by using the RelayCommand. I followed Josh Smith's excellent article on MVVM and have implemented the following. XAML Code <Button Command="{Binding Path=ACommandWithAParameter}" CommandParameter="Orange" HorizontalAlignment="Left" Style="{DynamicResource SimpleButton}" VerticalAlignment="Top" Content="Button"/> ViewModel Code public RelayCommand _aCommandWithAParameter; /// <summary> /// Returns a command with a parameter /// </summary> public RelayCommand ACommandWithAParameter { get { if (_aCommandWithAParameter == null) { _aCommandWithAParameter = new RelayCommand( param => this.CommandWithAParameter("Apple") ); } return _aCommandWithAParameter; } } public void CommandWithAParameter(String aParameter) { String theParameter = aParameter; } #endregion I set a breakpoint in the CommandWithAParameter method and observed that aParameter was set to "Apple", and not "Orange". This seems obvious as the method CommandWithAParameter is being called with the literal String "Apple". However, looking up the execution stack, I can see that "Orange", the CommandParameter I set in the XAML is the parameter value for RelayCommand implemenation of the ICommand Execute interface method. That is the value of parameter in the method below of the execution stack is "Orange", public void Execute(object parameter) { _execute(parameter); } What I am trying to figure out is how to create the RelayCommand ACommandWithAParameter property such that it can call the CommandWithAParameter method with the CommandParameter "Orange" defined in the XAML. Is there a way to do this? Why do I want to do this? Part of "On The Fly Localization" In my particular implementation I want to create a SetLanguage RelayCommand that can be bound to multiple buttons. I would like to pass the two character language identifier ("en", "es", "ja", etc) as the CommandParameter and have that be defined for each "set language" button defined in the XAML. I want to avoid having to create a SetLanguageToXXX command for each language supporting and hard coding the two character language identifier into each RelayCommand in the ViewModel.

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Why am I getting "ArgumentError: wrong number of arguments (1 for 0)" when running my rails function

- by Hisham

I'm stumped on what's causing this. I get this error and stack trace in all my functional tests where I call 'post'. Here is the full stack trace: 7) Error: test_should_validate(UsersControllerTest): ArgumentError: wrong number of arguments (1 for 0) /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/routing/route.rb:48:in `to_query' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/routing/route.rb:48:in `build_query_string' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/routing/route.rb:46:in `each' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/routing/route.rb:46:in `build_query_string' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/routing/route.rb:233:in `append_query_string' generated code (/Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/routing/route.rb:154):3:in `generate' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/routing/route_set.rb:365:in `__send__' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/routing/route_set.rb:365:in `generate' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/routing/route_set.rb:364:in `each' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/routing/route_set.rb:364:in `generate' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/url_rewriter.rb:208:in `rewrite_path' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/url_rewriter.rb:187:in `rewrite_url' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/url_rewriter.rb:165:in `rewrite' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/test_process.rb:450:in `build_request_uri' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/test_process.rb:406:in `process' /Users/hisham/src/rails/ftuBackend/vendor/rails/actionpack/lib/action_controller/test_process.rb:376:in `post' functional/users_controller_test.rb:57:in `test_should_validate' /Users/hisham/src/rails/ftuBackend/vendor/rails/activesupport/lib/active_support/testing/setup_and_teardown.rb:60:in `__send__' /Users/hisham/src/rails/ftuBackend/vendor/rails/activesupport/lib/active_support/testing/setup_and_teardown.rb:60:in `run' This is the test I'm running: def test_should_validate post :validate, :user => { :email => '[email protected]', :password => 'quire', :password_confirmation => 'quire', :agreed_to_terms => "true" } assert assigns(:user).errors.empty? assert_response :success end

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DevExpress AspxGridView clientside SelectionChanged problem when using paged ObjectDataSource

- by Constantin Baciu

The context is as follows: One DexExpress AspxGridView with a server-side paging/filtering/sorting mechanism (using ObjectDataSource). I've been having problems with the filter mechanism ( see this stack ). Now, the problem I'm having is this: the client-side events get mangled between DataSource events. :O . Let me explain what happens: if I change the page (or sort/filter for that matter), then, select one row from the grid, the client-side SelectionChanged event fires well. If I change the page (or sort/filter), the event doesn't fire anymore. Instead, on the server side, I get a "The method or operation is not implemented" exception with the following stack-trace: at DevExpress.Web.Data.WebDataProviderBase.GetListSouceRowValue(Int32 listSourceRowIndex, String fieldName) at DevExpress.Web.Data.WebDataProxy.GetListSourceRowValue(Int32 listSourceRowIndex, String fieldName) at DevExpress.Web.Data.WebDataProxy.GetKeyValueCore(Int32 index, GetKeyValueCallback getKeyValue) at DevExpress.Web.Data.WebDataSelectionBase.GetSelectedValues(String[] fieldNames, Int32 visibleStartIndex, Int32 visibleRowCountOnPage) at DevExpress.Web.Data.WebDataProxy.GetSelectedValues(String[] fieldNames) at DevExpress.Web.ASPxGridView.ASPxGridView.FBSelectFieldValues(String[] args) at DevExpress.Web.ASPxGridView.ASPxGridView.GetCallbackResultCore() at DevExpress.Web.ASPxGridView.ASPxGridView.GetCallbackResult() at DevExpress.Web.ASPxClasses.ASPxWebControl.System.Web.UI.ICallbackEventHandler.GetCallbackResult() Am I doing something wrong? Any help will be much appreciated.

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DevExpress AspxGridView clientside SelectionChanged problem when using paged ObjectDataSource

- by Constantin Baciu

The context is as follows: One DexExpress AspxGridView with a server-side paging/filtering/sorting mechanism (using ObjectDataSource). I've been having problems with the filter mechanism ( see this stack ). Now, the problem I'm having is this: the client-side events get mangled between DataSource events. :O . Let me explain what happens: if I change the page (or sort/filter for that matter), then, select one row from the grid, the client-side SelectionChanged event fires well. If I change the page (or sort/filter), the event doesn't fire anymore. Instead, on the server side, I get a "The method or operation is not implemented" exception with the following stack-trace: at DevExpress.Web.Data.WebDataProviderBase.GetListSouceRowValue(Int32 listSourceRowIndex, String fieldName) at DevExpress.Web.Data.WebDataProxy.GetListSourceRowValue(Int32 listSourceRowIndex, String fieldName) at DevExpress.Web.Data.WebDataProxy.GetKeyValueCore(Int32 index, GetKeyValueCallback getKeyValue) at DevExpress.Web.Data.WebDataSelectionBase.GetSelectedValues(String[] fieldNames, Int32 visibleStartIndex, Int32 visibleRowCountOnPage) at DevExpress.Web.Data.WebDataProxy.GetSelectedValues(String[] fieldNames) at DevExpress.Web.ASPxGridView.ASPxGridView.FBSelectFieldValues(String[] args) at DevExpress.Web.ASPxGridView.ASPxGridView.GetCallbackResultCore() at DevExpress.Web.ASPxGridView.ASPxGridView.GetCallbackResult() at DevExpress.Web.ASPxClasses.ASPxWebControl.System.Web.UI.ICallbackEventHandler.GetCallbackResult() Am I doing something wrong? Any help will be much appreciated.

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What good technology podcasts are out there?

- by Michael Stum

Yes, Podcasts, those nice little Audiobooks I can listen to on the way to work. With the current amount of Podcasts, it's like searching a needle in a haystack, except that the haystack happens to be the Internet and is filled with too many of these "Hot new Gadgets" stuff :( Now, even though I am mainly a .NET developer nowadays, maybe anyone knows some good Podcasts from people regarding the whole software lifecycle? Unit Testing, Continous Integration, Documentation, Deployment... So - what are you guys and gals listening to? Please note that the categorizations are somewhat subjective and may not be 100% accurate as many podcasts cover several areas. Categorization is made against what is considered the "main" area. General Software Engineering / Productivity Stack Overflow TekPub (Requires Paid Subscription) SE Radio 43 Folders Perspectives Dr. Dobb's (now a video feed) The Pragmatic Podcast (Inactive) IT Matters Agile Toolkit Podcast The Stack Trace (Inactive) Parleys Techzing The Startup Success Podcast Berkeley CS class lectures FOSS Weekly .NET / Visual Studio / Microsoft Herding Code Hanselminutes .NET Rocks! Deep Fried Bytes Alt.Net Podcast Polymorphic Podcast Sparkling Client (The Silverlight Podcast) dnrTV! Spaghetti Code ASP.NET Podcast Channel 9 Radio TFS PowerScripting Podcast The Thirsty Developer Elegant Code ConnectedShow Crafty Coders Coding QA jQuery yayQuery The official jQuery podcast Java / Groovy The Java Posse Grails Podcast Java Technology Insider Ruby / Rails Railscasts Rails Envy The Ruby on Rails Podcast Rubiverse Web Design / JavaScript / Ajax WebDevRadio Boagworld The Rissington podcast Ajaxian YUI Theater Unix / Linux / Mac / iPhone Mac Developer Network Hacker Public Radio Linux Outlaws Mac OS Ken LugRadio Linux radio show (Inactive) The Linux Action Show! Linux Kernel Mailing List (LKML) Summary Podcast Stanford's iPhone programming class SysAdmin, Security or Infrastructure RunAs Radio Security Now! Crypto-Gram Security Podcast Hak5 VMWare VMTN Windows Weekly PaulDotCom Security The Register - Semi-Coherent Computing FeatherCast General Tech / Business Tekzilla This Week in Tech The Guardian Tech Weekly PCMag Radio Podcast Entrepreneurship Corner Manager Tools Other / Misc. / Podcast Networks IT Conversations Retrobits Podcast No Agenda Netcast Cranky Geeks The Command Line Freelance Radio IBM developerWorks The Register - Open Season Drunk and Retired Technometria Sod This Radio4Nerds Hacker Medley

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How to implement Gmail OAuth API to send email (especially via SMTP)?

- by Curtis Gibby

I'm developing a web application that will send emails on behalf of a logged-in user. I'm trying to use the new Gmail OAuth protocol announced described here to send these emails through the user's Gmail account (preferably using SMTP rather than IMAP, but I'm easy). However, the sample PHP code gives me a couple of problems. All of the sample code is based on IMAP, not SMTP. Why "support" the SMTP protocol if you're not going to show people how to use it? The sample code gives me a fatal error from an uncaught Zend exception -- it can't find the "INBOX" folder. Fatal error: Uncaught exception 'Zend_Mail_Storage_Exception' with message 'cannot change folder, maybe it does not exist' in path\to\xoauth-php-samples\Zend\Mail\Storage\Imap.php:467 Stack trace: #0 path\to\xoauth-php-samples\Zend\Mail\Storage\Imap.php(248): Zend_Mail_Storage_Imap-selectFolder('INBOX') #1 path\to\xoauth-php-samples\three-legged.php(184): Zend_Mail_Storage_Imap-__construct(Object(Zend_Mail_Protocol_Imap)) #2 {main} Next exception 'Zend_Mail_Storage_Exception' with message 'cannot select INBOX, is this a valid transport?' in path\to\xoauth-php-samples\Zend\Mail\Storage\Imap.php:254 Stack trace: #0 path\to\xoauth-php-samples\three-legged.php(184): Zend_Mail_Storage_Imap-__construct(Object(Zend_Mail_Protocol_Imap)) #1 {main} in path\to\xoauth-php-samples\Zend\Mail\Storage\Imap.php on line 254 I've verified that I'm getting good OAuth tokens back, I just don't know how to make the actual email transaction happen. This protocol is still rather new, so there's not much unofficial community documentation about it out there, and the official docs are unhelpfully dry stuff about the SMTP RFC. So if anyone can help get this going, I'd greatly appreciate it. Note: I've already been able to connect to Gmail's SMTP server via SSL and successfully send an email, provided that the user has given my application his/her Gmail username and password. I'd like to avoid this method, because it encourages phishing and security-minded users won't accept it. This question is not about that.

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javax.ejb.NoSuchEJBException after redeploying EJBs

- by vetler

Using Glassfish 3.0.1 ... If I have a web application accessing EJBs in another application remotely, and the remote application containing the EJBs is redeployed, I get a javax.ejb.NoSuchEJBException (see stacktrace below). Shouldn't this work? I can see that the EJB in question was successfully deployed, using the exact same JNDI name. Is there any other way to fix this than to restart the web application? It should be noted that in this particular example that the stacktrace is from, I'm accessing a servlet that injects the bean with CDI: public class StatusServlet extends HttpServlet { @Inject private StatusService statusService; @Override public void doGet(final HttpServletRequest req, final HttpServletResponse res) throws IOException { res.getWriter().write(statusService.getStatus()); } } The injection is done with the following producer to get the right EJB: public class StatusServiceProducer extends AbstractServiceProducer { @EJB(name = "StatusService") private StatusService service; @Produces public StatusService getService(final InjectionPoint ip) { return service; } } A producer is used to make it easier to wrap the service in a proxy, and to make it easier to change how the EJBs are looked up. The StatusService interface and implementation is as follows: @Stateless(name = "StatusService") public class StatusServiceImpl implements StatusService { private static final String OK = "OK"; public String getStatus() { // Some code return OK; } } public interface StatusService { String getStatus(); } Full stacktrace: [#|2011-01-12T10:45:28.273+0100|WARNING|glassfish3.0.1|javax.enterprise.system.container.web.com.sun.enterprise.web|_ThreadID=50;_ThreadName=http-thread-pool-8080-(1);|StandardWrapperValve[Load Balancer status servlet]: PWC1406: Servlet.service() for servlet Load Balancer status servlet threw exception javax.ejb.NoSuchEJBException at org.example.service._StatusService_Wrapper.getStatus(org/example/service/_StatusService_Wrapper.java) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at no.evote.service.cache.ServiceInvocationHandler.invoke(ServiceInvocationHandler.java:34) at $Proxy760.getStatus(Unknown Source) at no.evote.presentation.StatusServlet.doGet(StatusServlet.java:25) at javax.servlet.http.HttpServlet.service(HttpServlet.java:734) at javax.servlet.http.HttpServlet.service(HttpServlet.java:847) at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1523) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:343) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:215) at net.balusc.http.multipart.MultipartFilter.doFilter(MultipartFilter.java:78) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:215) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:277) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:188) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:641) at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:97) at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:85) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:185) at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:325) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:226) at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:165) at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:791) at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:693) at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:954) at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:170) at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:135) at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:102) at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:88) at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:76) at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:53) at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:57) at com.sun.grizzly.ContextTask.run(ContextTask.java:69) at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:330) at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:309) at java.lang.Thread.run(Thread.java:662) Caused by: java.rmi.NoSuchObjectException: CORBA OBJECT_NOT_EXIST 1330446338 No; nested exception is: org.omg.CORBA.OBJECT_NOT_EXIST: ----------BEGIN server-side stack trace---------- org.omg.CORBA.OBJECT_NOT_EXIST: vmcid: OMG minor code: 2 completed: No at com.sun.corba.ee.impl.logging.OMGSystemException.noObjectAdaptor(OMGSystemException.java:3457) at com.sun.corba.ee.impl.logging.OMGSystemException.noObjectAdaptor(OMGSystemException.java:3475) at com.sun.corba.ee.impl.oa.poa.POAFactory.find(POAFactory.java:222) at com.sun.corba.ee.impl.protocol.CorbaServerRequestDispatcherImpl.findObjectAdapter(CorbaServerRequestDispatcherImpl.java:450) at com.sun.corba.ee.impl.protocol.CorbaServerRequestDispatcherImpl.dispatch(CorbaServerRequestDispatcherImpl.java:209) at com.sun.corba.ee.impl.protocol.CorbaMessageMediatorImpl.handleRequestRequest(CorbaMessageMediatorImpl.java:1841) at com.sun.corba.ee.impl.protocol.SharedCDRClientRequestDispatcherImpl.marshalingComplete(SharedCDRClientRequestDispatcherImpl.java:119) at com.sun.corba.ee.impl.protocol.CorbaClientDelegateImpl.invoke(CorbaClientDelegateImpl.java:235) at com.sun.corba.ee.impl.presentation.rmi.StubInvocationHandlerImpl.privateInvoke(StubInvocationHandlerImpl.java:187) at com.sun.corba.ee.impl.presentation.rmi.StubInvocationHandlerImpl.invoke(StubInvocationHandlerImpl.java:147) at com.sun.corba.ee.impl.presentation.rmi.codegen.CodegenStubBase.invoke(CodegenStubBase.java:225) at no.evote.service.__StatusService_Remote_DynamicStub.getStatus(no/evote/service/__StatusService_Remote_DynamicStub.java) at no.evote.service._StatusService_Wrapper.getStatus(no/evote/service/_StatusService_Wrapper.java) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at no.evote.service.cache.ServiceInvocationHandler.invoke(ServiceInvocationHandler.java:34) at $Proxy760.getStatus(Unknown Source) at no.evote.presentation.StatusServlet.doGet(StatusServlet.java:25) at javax.servlet.http.HttpServlet.service(HttpServlet.java:734) at javax.servlet.http.HttpServlet.service(HttpServlet.java:847) at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1523) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:343) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:215) at net.balusc.http.multipart.MultipartFilter.doFilter(MultipartFilter.java:78) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:215) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:277) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:188) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:641) at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:97) at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:85) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:185) at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:325) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:226) at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:165) at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:791) at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:693) at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:954) at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:170) at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:135) at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:102) at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:88) at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:76) at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:53) at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:57) at com.sun.grizzly.ContextTask.run(ContextTask.java:69) at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:330) at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:309) at java.lang.Thread.run(Thread.java:662) Caused by: org.omg.PortableServer.POAPackage.AdapterNonExistent: IDL:omg.org/PortableServer/POA/AdapterNonExistent:1.0 at com.sun.corba.ee.impl.oa.poa.POAImpl.find_POA(POAImpl.java:1057) at com.sun.corba.ee.impl.oa.poa.POAFactory.find(POAFactory.java:218) ... 48 more ----------END server-side stack trace---------- vmcid: OMG minor code: 2 completed: No at com.sun.corba.ee.impl.javax.rmi.CORBA.Util.mapSystemException(Util.java:280) at com.sun.corba.ee.impl.presentation.rmi.StubInvocationHandlerImpl.privateInvoke(StubInvocationHandlerImpl.java:200) at com.sun.corba.ee.impl.presentation.rmi.StubInvocationHandlerImpl.invoke(StubInvocationHandlerImpl.java:147) at com.sun.corba.ee.impl.presentation.rmi.codegen.CodegenStubBase.invoke(CodegenStubBase.java:225) at no.evote.service.__StatusService_Remote_DynamicStub.getStatus(no/evote/service/__StatusService_Remote_DynamicStub.java) ... 39 more Caused by: org.omg.CORBA.OBJECT_NOT_EXIST: ----------BEGIN server-side stack trace---------- org.omg.CORBA.OBJECT_NOT_EXIST: vmcid: OMG minor code: 2 completed: No at com.sun.corba.ee.impl.logging.OMGSystemException.noObjectAdaptor(OMGSystemException.java:3457) at com.sun.corba.ee.impl.logging.OMGSystemException.noObjectAdaptor(OMGSystemException.java:3475) at com.sun.corba.ee.impl.oa.poa.POAFactory.find(POAFactory.java:222) at com.sun.corba.ee.impl.protocol.CorbaServerRequestDispatcherImpl.findObjectAdapter(CorbaServerRequestDispatcherImpl.java:450) at com.sun.corba.ee.impl.protocol.CorbaServerRequestDispatcherImpl.dispatch(CorbaServerRequestDispatcherImpl.java:209) at com.sun.corba.ee.impl.protocol.CorbaMessageMediatorImpl.handleRequestRequest(CorbaMessageMediatorImpl.java:1841) at com.sun.corba.ee.impl.protocol.SharedCDRClientRequestDispatcherImpl.marshalingComplete(SharedCDRClientRequestDispatcherImpl.java:119) at com.sun.corba.ee.impl.protocol.CorbaClientDelegateImpl.invoke(CorbaClientDelegateImpl.java:235) at com.sun.corba.ee.impl.presentation.rmi.StubInvocationHandlerImpl.privateInvoke(StubInvocationHandlerImpl.java:187) at com.sun.corba.ee.impl.presentation.rmi.StubInvocationHandlerImpl.invoke(StubInvocationHandlerImpl.java:147) at com.sun.corba.ee.impl.presentation.rmi.codegen.CodegenStubBase.invoke(CodegenStubBase.java:225) at no.evote.service.__StatusService_Remote_DynamicStub.getStatus(no/evote/service/__StatusService_Remote_DynamicStub.java) at no.evote.service._StatusService_Wrapper.getStatus(no/evote/service/_StatusService_Wrapper.java) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at no.evote.service.cache.ServiceInvocationHandler.invoke(ServiceInvocationHandler.java:34) at $Proxy760.getStatus(Unknown Source) at no.evote.presentation.StatusServlet.doGet(StatusServlet.java:25) at javax.servlet.http.HttpServlet.service(HttpServlet.java:734) at javax.servlet.http.HttpServlet.service(HttpServlet.java:847) at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1523) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:343) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:215) at net.balusc.http.multipart.MultipartFilter.doFilter(MultipartFilter.java:78) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:215) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:277) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:188) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:641) at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:97) at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:85) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:185) at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:325) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:226) at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:165) at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:791) at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:693) at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:954) at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:170) at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:135) at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:102) at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:88) at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:76) at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:53) at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:57) at com.sun.grizzly.ContextTask.run(ContextTask.java:69) at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:330) at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:309) at java.lang.Thread.run(Thread.java:662) Caused by: org.omg.PortableServer.POAPackage.AdapterNonExistent: IDL:omg.org/PortableServer/POA/AdapterNonExistent:1.0 at com.sun.corba.ee.impl.oa.poa.POAImpl.find_POA(POAImpl.java:1057) at com.sun.corba.ee.impl.oa.poa.POAFactory.find(POAFactory.java:218) ... 48 more ----------END server-side stack trace---------- vmcid: OMG minor code: 2 completed: No at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27) at java.lang.reflect.Constructor.newInstance(Constructor.java:513) at com.sun.corba.ee.impl.protocol.giopmsgheaders.MessageBase.getSystemException(MessageBase.java:913) at com.sun.corba.ee.impl.protocol.giopmsgheaders.ReplyMessage_1_2.getSystemException(ReplyMessage_1_2.java:129) at com.sun.corba.ee.impl.protocol.CorbaMessageMediatorImpl.getSystemExceptionReply(CorbaMessageMediatorImpl.java:681) at com.sun.corba.ee.impl.protocol.CorbaClientRequestDispatcherImpl.processResponse(CorbaClientRequestDispatcherImpl.java:510) at com.sun.corba.ee.impl.protocol.SharedCDRClientRequestDispatcherImpl.marshalingComplete(SharedCDRClientRequestDispatcherImpl.java:153) at com.sun.corba.ee.impl.protocol.CorbaClientDelegateImpl.invoke(CorbaClientDelegateImpl.java:235) at com.sun.corba.ee.impl.presentation.rmi.StubInvocationHandlerImpl.privateInvoke(StubInvocationHandlerImpl.java:187) ... 42 more |#]

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Parallelism in .NET – Part 12, More on Task Decomposition

- by Reed

Many tasks can be decomposed using a Data Decomposition approach, but often, this is not appropriate. Frequently, decomposing the problem into distinctive tasks that must be performed is a more natural abstraction. However, as I mentioned in Part 1, Task Decomposition tends to be a bit more difficult than data decomposition, and can require a bit more effort. Before we being parallelizing our algorithm based on the tasks being performed, we need to decompose our problem, and take special care of certain considerations such as ordering and grouping of tasks. Up to this point in this series, I’ve focused on parallelization techniques which are most appropriate when a problem space can be decomposed by data. Using PLINQ and the Parallel class, I’ve shown how problem spaces where there is a collection of data, and each element needs to be processed, can potentially be parallelized. However, there are many other routines where this is not appropriate. Often, instead of working on a collection of data, there is a single piece of data which must be processed using an algorithm or series of algorithms. Here, there is no collection of data, but there may still be opportunities for parallelism. As I mentioned before, in cases like this, the approach is to look at your overall routine, and decompose your problem space based on tasks. The idea here is to look for discrete “tasks,” individual pieces of work which can be conceptually thought of as a single operation. Let’s revisit the example I used in Part 1, an application startup path. Say we want our program, at startup, to do a bunch of individual actions, or “tasks”. The following is our list of duties we must perform right at startup: Display a splash screen Request a license from our license manager Check for an update to the software from our web server If an update is available, download it Setup our menu structure based on our current license Open and display our main, welcome Window Hide the splash screen The first step in Task Decomposition is breaking up the problem space into discrete tasks. This, naturally, can be abstracted as seven discrete tasks. In the serial version of our program, if we were to diagram this, the general process would appear as: These tasks, obviously, provide some opportunities for parallelism. Before we can parallelize this routine, we need to analyze these tasks, and find any dependencies between tasks. In this case, our dependencies include: The splash screen must be displayed first, and as quickly as possible. We can’t download an update before we see whether one exists. Our menu structure depends on our license, so we must check for the license before setting up the menus. Since our welcome screen will notify the user of an update, we can’t show it until we’ve downloaded the update. Since our welcome screen includes menus that are customized based off the licensing, we can’t display it until we’ve received a license. We can’t hide the splash until our welcome screen is displayed. By listing our dependencies, we start to see the natural ordering that must occur for the tasks to be processed correctly. The second step in Task Decomposition is determining the dependencies between tasks, and ordering tasks based on their dependencies. Looking at these tasks, and looking at all the dependencies, we quickly see that even a simple decomposition such as this one can get quite complicated. In order to simplify the problem of defining the dependencies, it’s often a useful practice to group our tasks into larger, discrete tasks. The goal when grouping tasks is that you want to make each task “group” have as few dependencies as possible to other tasks or groups, and then work out the dependencies within that group. Typically, this works best when any external dependency is based on the “last” task within the group when it’s ordered, although that is not a firm requirement. This process is often called Grouping Tasks. In our case, we can easily group together tasks, effectively turning this into four discrete task groups: 1. Show our splash screen – This needs to be left as its own task. First, multiple things depend on this task, mainly because we want this to start before any other action, and start as quickly as possible. 2. Check for Update and Download the Update if it Exists - These two tasks logically group together. We know we only download an update if the update exists, so that naturally follows. This task has one dependency as an input, and other tasks only rely on the final task within this group. 3. Request a License, and then Setup the Menus – Here, we can group these two tasks together. Although we mentioned that our welcome screen depends on the license returned, it also depends on setting up the menu, which is the final task here. Setting up our menus cannot happen until after our license is requested. By grouping these together, we further reduce our problem space. 4. Display welcome and hide splash - Finally, we can display our welcome window and hide our splash screen. This task group depends on all three previous task groups – it cannot happen until all three of the previous groups have completed. By grouping the tasks together, we reduce our problem space, and can naturally see a pattern for how this process can be parallelized. The diagram below shows one approach: The orange boxes show each task group, with each task represented within. We can, now, effectively take these tasks, and run a large portion of this process in parallel, including the portions which may be the most time consuming. We’ve now created two parallel paths which our process execution can follow, hopefully speeding up the application startup time dramatically. The main point to remember here is that, when decomposing your problem space by tasks, you need to: Define each discrete action as an individual Task Discover dependencies between your tasks Group tasks based on their dependencies Order the tasks and groups of tasks

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How to Loop through LINQ results (VB.NET)

- by rockinthesixstring

I've got some code to try and loop through LINQ results, but it doesn't seem to be working. HERE'S THE CODE Public Sub ProcessRequest(ByVal context As System.Web.HttpContext) Implements System.Web.IHttpHandler.ProcessRequest ' the page contenttype is plain text' HttpContext.Current.Response.ContentType = "text/plain" ' store the querystring as a variable' Dim qs As Nullable(Of Integer) = Integer.TryParse(HttpContext.Current.Request.QueryString("ID"), Nothing) ' use the RegionsDataContext' Using RegionDC As New DAL.RegionsDataContext 'create a (q)uery variable' Dim q As Object ' if the querystring PID is not blank' ' then we want to return results based on the PID' If Not qs Is Nothing Then ' that fit within the Parent ID' q = (From r In RegionDC.bt_Regions _ Where r.PID = qs _ Select r.Region).ToArray ' now we loop through the array' ' and write out the ressults' For Each item As DAL.bt_Region In q HttpContext.Current.Response.Write(item.Region & vbCrLf) Next End If End Using End Sub HERE'S THE ERROR Public member 'Region' on type 'String' not found. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.MissingMemberException: Public member 'Region' on type 'String' not found. Source Error: Line 33: ' and write out the ressults Line 34: For Each item In q Line 35: HttpContext.Current.Response.Write(item.Region & vbCrLf) Line 36: Next Line 37: Source File: E:\Projects\businesstrader\App_Code\Handlers\RegionsAutoComplete.vb Line: 35 Stack Trace: [MissingMemberException: Public member 'Region' on type 'String' not found.] Microsoft.VisualBasic.CompilerServices.Container.GetMembers(String& MemberName, Boolean ReportErrors) +509081 Microsoft.VisualBasic.CompilerServices.NewLateBinding.LateGet(Object Instance, Type Type, String MemberName, Object[] Arguments, String[] ArgumentNames, Type[] TypeArguments, Boolean[] CopyBack) +222 BT.Handlers.RegionsAutoComplete.ProcessRequest(HttpContext context) in E:\Projects\businesstrader\App_Code\Handlers\RegionsAutoComplete.vb:35 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +181 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +75 Can anyone tell me what I'm doing wrong?

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I can't understand this issue java.lang.IndexOutOfBoundsException.

- by praveenb

I've strange issue, that My application is working fine on some devices, But its crashing one of the client device(on Galaxy Nexus 4.1.1 v) at app starting screen. I get this stack trace from ACRA report. java.lang.IndexOutOfBoundsException at android.graphics.Paint.getTextRunAdvances(Paint.java:1731) at android.graphics.Paint.getTextRunAdvances(Paint.java:1704) at android.text.MeasuredText.addStyleRun(MeasuredText.java:164) at android.text.MeasuredText.addStyleRun(MeasuredText.java:204) at android.text.StaticLayout.generate(StaticLayout.java:281) at android.text.DynamicLayout.reflow(DynamicLayout.java:284) at android.text.DynamicLayout.(DynamicLayout.java:170) at android.widget.TextView.makeSingleLayout(TextView.java:5843) at android.widget.TextView.makeNewLayout(TextView.java:5741) at android.widget.TextView.onMeasure(TextView.java:6098) at android.view.View.measure(View.java:15172) at android.widget.LinearLayout.measureVertical(LinearLayout.java:833) at android.widget.LinearLayout.onMeasure(LinearLayout.java:574) at android.view.View.measure(View.java:15172) at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:617) at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:399) at android.view.View.measure(View.java:15172) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814) at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) at android.view.View.measure(View.java:15172) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814) at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1390) at android.widget.LinearLayout.measureVertical(LinearLayout.java:681) at android.widget.LinearLayout.onMeasure(LinearLayout.java:574) at android.view.View.measure(View.java:15172) at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814) at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2148) at android.view.View.measure(View.java:15172) at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1848) at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1100) at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1273) at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:998) at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4212) at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725) at android.view.Choreographer.doCallbacks(Choreographer.java:555) at android.view.Choreographer.doFrame(Choreographer.java:525) at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711) at android.os.Handler.handleCallback(Handler.java:615) at android.os.Handler.dispatchMessage(Handler.java:92) at android.os.Looper.loop(Looper.java:137) at android.app.ActivityThread.main(ActivityThread.java:4745) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:511) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) at dalvik.system.NativeStart.main(Native Method) Im seeing above stack trace. I'm unable to understand the issue. Please help me on tacking the issue. Thank you.

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F# Powerpack's Metadata doesn't recognize FSharp.Core as an F# library

- by Nathan Sanders

Here's my test code to isolate the problem: open Microsoft.FSharp.Metadata [<EntryPoint>] let main args = let core = FSharpAssembly.FromFile @"C:\Program Files\FSharp-2.0.0.0\\bin\FSharp.Core.dll" let core2 = FSharpAssembly.FSharpLibrary let core3 = System.AppDomain.CurrentDomain.GetAssemblies() |> Seq.find (fun a -> a.FullName.Contains "Core") |> FSharpAssembly.FromAssembly core.Entities |> Seq.iter (printfn "%A") 0 All three lets should give me the same FSharpAssembly. Instead, all 3 throw an exception that FSharp.Core is not an F# assembly (details below, re-formatted for readability). Two more clues: Using the core3 method, I get the same error for the test F# assembly itself I don't get the error at FSI after doing #r "@C:\Program Files...\FSharp.Powerpack.Metadata.dll". Any ideas? I'm using Visual Studio 2008, F# 2.0 and F# Powerpack 2.0.0.0 (May 20, 2010) release on an oldish XP VM, I think it's updated to SP3 though. (I got the error this morning with Powerpack 1.9.9.9, so I upgraded to 2.0.0.0. I thought that if 1.9.9.9 doesn't recognise F#'s 2.0.0.0's assemblies, then maybe bugfixes in Powerpack 2.0.0.0 would help.) Unhandled Exception: System.TypeInitializationException: The type initializer for 'Microsoft.FSharp.Metadata.AssemblyLoader' threw an exception. ---> System.TypeInitializationException: The type initializer for '<StartupCode$FSharp-PowerPack-Metadata>.$Metadata' threw an exception. ---> System.ArgumentException: could not produce an FSharpAssembly object for the assembly 'FSharp.Core' because this is not an F# assembly Parameter name: name at Microsoft.FSharp.Metadata.AssemblyLoader.Add(String name,Assembly assembly) at <StartupCode$FSharp-PowerPack-Metadata>.$Metadata..cctor() --- End of inner exception stack trace --- at Microsoft.FSharp.Metadata.AssemblyLoader..cctor() --- End of inner exception stack trace --- at Microsoft.FSharp.Metadata.AssemblyLoader.Get(Assembly assembly) at Microsoft.FSharp.Metadata.FSharpAssembly.FromAssembly(Assembly assembly) at Program.main(String[] args) in C:\Documents an...\FSMetadataTest\Program.fs:line 11 Press any key to continue . . .

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Why am I getting a " instance has no attribute 'getitem' " error?

- by Kevin Yusko

Here's the code: class BinaryTree: def __init__(self,rootObj): self.key = rootObj self.left = None self.right = None root = [self.key, self.left, self.right] def getRootVal(root): return root[0] def setRootVal(newVal): root[0] = newVal def getLeftChild(root): return root[1] def getRightChild(root): return root[2] def insertLeft(self,newNode): if self.left == None: self.left = BinaryTree(newNode) else: t = BinaryTree(newNode) t.left = self.left self.left = t def insertRight(self,newNode): if self.right == None: self.right = BinaryTree(newNode) else: t = BinaryTree(newNode) t.right = self.right self.right = t def buildParseTree(fpexp): fplist = fpexp.split() pStack = Stack() eTree = BinaryTree('') pStack.push(eTree) currentTree = eTree for i in fplist: if i == '(': currentTree.insertLeft('') pStack.push(currentTree) currentTree = currentTree.getLeftChild() elif i not in '+-*/)': currentTree.setRootVal(eval(i)) parent = pStack.pop() currentTree = parent elif i in '+-*/': currentTree.setRootVal(i) currentTree.insertRight('') pStack.push(currentTree) currentTree = currentTree.getRightChild() elif i == ')': currentTree = pStack.pop() else: print "error: I don't recognize " + i return eTree def postorder(tree): if tree != None: postorder(tree.getLeftChild()) postorder(tree.getRightChild()) print tree.getRootVal() def preorder(self): print self.key if self.left: self.left.preorder() if self.right: self.right.preorder() def inorder(tree): if tree != None: inorder(tree.getLeftChild()) print tree.getRootVal() inorder(tree.getRightChild()) class Stack: def __init__(self): self.items = [] def isEmpty(self): return self.items == [] def push(self, item): self.items.append(item) def pop(self): return self.items.pop() def peek(self): return self.items[len(self.items)-1] def size(self): return len(self.items) def main(): parseData = raw_input( "Please enter the problem you wished parsed.(NOTE: problem must have parenthesis to seperate each binary grouping and must be spaced out.) " ) tree = buildParseTree(parseData) print( "The post order is: ", + postorder(tree)) print( "The post order is: ", + postorder(tree)) print( "The post order is: ", + preorder(tree)) print( "The post order is: ", + inorder(tree)) main() And here is the error: Please enter the problem you wished parsed.(NOTE: problem must have parenthesis to seperate each binary grouping and must be spaced out.) ( 1 + 2 ) Traceback (most recent call last): File "C:\Users\Kevin\Desktop\Python Stuff\Assignment 11\parseTree.py", line 108, in main() File "C:\Users\Kevin\Desktop\Python Stuff\Assignment 11\parseTree.py", line 102, in main tree = buildParseTree(parseData) File "C:\Users\Kevin\Desktop\Python Stuff\Assignment 11\parseTree.py", line 46, in buildParseTree currentTree = currentTree.getLeftChild() File "C:\Users\Kevin\Desktop\Python Stuff\Assignment 11\parseTree.py", line 15, in getLeftChild return root[1] AttributeError: BinaryTree instance has no attribute '__getitem__'

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Error when installing plugin in Eclipse

- by Derk

When I try to install a plugin in Eclipse I get these error messages Registry event dispatcher Error notifying registry change listener. Error notifying registry change listener. Invalid registry object Error notifying registry change listener. Invalid registry object Error notifying registry change listener. Invalid registry object Error notifying registry change listener. Invalid registry object Error notifying registry change listener. Invalid registry object Has someone an idea what the cause of this problem could be? Thanks Edit: I see the Eclipse .log file has also a lot of new stack traces The first one is java.vendor=Sun Microsystems Inc. BootLoader constants: OS=win32, ARCH=x86_64, WS=win32, NL=nl_NL Framework arguments: -product org.eclipse.epp.package.jee.product Command-line arguments: -os win32 -ws win32 -arch x86_64 -product org.eclipse.epp.package.jee.product !ENTRY org.eclipse.equinox.registry 4 2 2010-05-06 21:04:31.236 !MESSAGE Problems occurred when invoking code from plug-in: "org.eclipse.equinox.registry". !STACK 0 org.eclipse.core.runtime.InvalidRegistryObjectException: Invalid registry object at org.eclipse.core.internal.registry.TemporaryObjectManager.getObject(TemporaryObjectManager.java:98) at org.eclipse.core.internal.registry.BaseExtensionPointHandle.getExtensionPoint(BaseExtensionPointHandle.java:106) at org.eclipse.core.internal.registry.BaseExtensionPointHandle.getContributor(BaseExtensionPointHandle.java:45) at org.eclipse.core.internal.registry.BaseExtensionPointHandle.getNamespace(BaseExtensionPointHandle.java:37) at org.eclipse.ui.internal.PopupMenuExtender.registryChanged(PopupMenuExtender.java:520) at org.eclipse.core.internal.registry.ExtensionRegistry$2.run(ExtensionRegistry.java:921) at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42) at org.eclipse.core.internal.registry.ExtensionRegistry.processChangeEvent(ExtensionRegistry.java:919) at org.eclipse.core.runtime.spi.RegistryStrategy.processChangeEvent(RegistryStrategy.java:260) at org.eclipse.core.internal.registry.osgi.ExtensionEventDispatcherJob.run(ExtensionEventDispatcherJob.java:50) at org.eclipse.core.internal.jobs.Worker.run(Worker.java:54)

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