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• Is "Systems Designer" the job title that best describes what I do? [closed]

  - by ivo-rossi

  After having worked as Java developer for almost 3 years in the same company that I currently work at, I moved to a new position associated with the development of the same application. I’m in this new position for more than 1 year now. My official job title is Systems Designer, but I’m not sure this is a title that expresses well what I do. So my question here is what would be the most appropriate job title for me? I see this question as important for my career development. After all, I should be able to explain in one word what I do. And it’s no longer “Java Developer”. Well, in more than one word, this is what I do: The business analysts gather requirements / business problems to be solved with the clients and then discuss these requirements with me. Given the requirements, I design the high level solutions to be implemented in our system (e.g. a new screen on the client application, modifications to existing reports, extension to the XML export format of some objects, etc). I base my decision on the current capabilities of the system, the overall impact that the solutions would have on the system and the estimated effort to implement them (as I was a developer of this same application for almost 3 years before I moved to this position, I’m confident in my estimates). The solutions are discussed iteratively with the business analysts until we agree that they are good. The outcome of this analysis is what we call the “requirements design” document, which is written by me, shared with clients for approval and then also with the team that is going to implement the solutions and test them. Note that there are a few problems that I need to find a solution for that are non-functional. If the users are unhappy with the performance of a certain tool, I will investigate what can be done to speed it up. I will do some research – often based in the Java code itself - to identify possibilities of optimizations. But in this new position I no longer code, the main outcome of my work is really the “requirements design”. Is “Systems Designer” really the most appropriate job title?

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• Memory Leak with Swing Drag and Drop

  - by tom

  I have a JFrame that accepts top-level drops of files. However after a drop has occurred, references to the frame are held indefinitely inside some Swing internal classes. I believe that disposing of the frame should release all of its resources, so what am I doing wrong? Example import java.awt.datatransfer.DataFlavor; import java.io.File; import java.util.List; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.TransferHandler; public class DnDLeakTester extends JFrame { public static void main(String[] args) { new DnDLeakTester(); //Prevent main from returning or the jvm will exit while (true) { try { Thread.sleep(10000); } catch (InterruptedException e) { } } } public DnDLeakTester() { super("I'm leaky"); add(new JLabel("Drop stuff here")); setTransferHandler(new TransferHandler() { @Override public boolean canImport(final TransferSupport support) { return (support.isDrop() && support .isDataFlavorSupported(DataFlavor.javaFileListFlavor)); } @Override public boolean importData(final TransferSupport support) { if (!canImport(support)) { return false; } try { final List<File> files = (List<File>) support.getTransferable().getTransferData(DataFlavor.javaFileListFlavor); for (final File f : files) { System.out.println(f.getName()); } } catch (Exception e) { e.printStackTrace(); } return true; } }); setDefaultCloseOperation(DISPOSE_ON_CLOSE); pack(); setVisible(true); } } To reproduce, run the code and drop some files on the frame. Close the frame so it's disposed of. To verify the leak I take a heap dump using JConsole and analyse it with the Eclipse Memory Analysis tool. It shows that sun.awt.AppContext is holding a reference to the frame through its hashmap. It looks like TransferSupport is at fault. What am I doing wrong? Should I be asking the DnD support code to clean itself up somehow? I'm running JDK 1.6 update 19.

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• Persistent (purely functional) Red-Black trees on disk performance

  - by Waneck

  I'm studying the best data structures to implement a simple open-source object temporal database, and currently I'm very fond of using Persistent Red-Black trees to do it. My main reasons for using persistent data structures is first of all to minimize the use of locks, so the database can be as parallel as possible. Also it will be easier to implement ACID transactions and even being able to abstract the database to work in parallel on a cluster of some kind. The great thing of this approach is that it makes possible implementing temporal databases almost for free. And this is something quite nice to have, specially for web and for data analysis (e.g. trends). All of this is very cool, but I'm a little suspicious about the overall performance of using a persistent data structure on disk. Even though there are some very fast disks available today, and all writes can be done asynchronously, so a response is always immediate, I don't want to build all application under a false premise, only to realize it isn't really a good way to do it. Here's my line of thought: - Since all writes are done asynchronously, and using a persistent data structure will enable not to invalidate the previous - and currently valid - structure, the write time isn't really a bottleneck. - There are some literature on structures like this that are exactly for disk usage. But it seems to me that these techniques will add more read overhead to achieve faster writes. But I think that exactly the opposite is preferable. Also many of these techniques really do end up with a multi-versioned trees, but they aren't strictly immutable, which is something very crucial to justify the persistent overhead. - I know there still will have to be some kind of locking when appending values to the database, and I also know there should be a good garbage collecting logic if not all versions are to be maintained (otherwise the file size will surely rise dramatically). Also a delta compression system could be thought about. - Of all search trees structures, I really think Red-Blacks are the most close to what I need, since they offer the least number of rotations. But there are some possible pitfalls along the way: - Asynchronous writes -could- affect applications that need the data in real time. But I don't think that is the case with web applications, most of the time. Also when real-time data is needed, another solutions could be devised, like a check-in/check-out system of specific data that will need to be worked on a more real-time manner. - Also they could lead to some commit conflicts, though I fail to think of a good example of when it could happen. Also commit conflicts can occur in normal RDBMS, if two threads are working with the same data, right? - The overhead of having an immutable interface like this will grow exponentially and everything is doomed to fail soon, so this all is a bad idea. Any thoughts? Thanks! edit: There seems to be a misunderstanding of what a persistent data structure is: http://en.wikipedia.org/wiki/Persistent_data_structure

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• gcc optimization? bug? and its practial implication to project

  - by kumar_m_kiran

  Hi All, My questions are divided into three parts Question 1 Consider the below code, #include <iostream> using namespace std; int main( int argc, char *argv[]) { const int v = 50; int i = 0X7FFFFFFF; cout<<(i + v)<<endl; if ( i + v < i ) { cout<<"Number is negative"<<endl; } else { cout<<"Number is positive"<<endl; } return 0; } No specific compiler optimisation options are used or the O's flag is used. It is basic compilation command g++ -o test main.cpp is used to form the executable. The seemingly very simple code, has odd behaviour in SUSE 64 bit OS, gcc version 4.1.2. The expected output is "Number is negative", instead only in SUSE 64 bit OS, the output would be "Number is positive". After some amount of analysis and doing a 'disass' of the code, I find that the compiler optimises in the below format - Since i is same on both sides of comparison, it cannot be changed in the same expression, remove 'i' from the equation. Now, the comparison leads to if ( v < 0 ), where v is a constant positive, So during compilation itself, the else part cout function address is added to the register. No cmp/jmp instructions can be found. I see that the behaviour is only in gcc 4.1.2 SUSE 10. When tried in AIX 5.1/5.3 and HP IA64, the result is as expected. Is the above optimisation valid? Or, is using the overflow mechanism for int not a valid use case? Question 2 Now when I change the conditional statement from if (i + v < i) to if ( (i + v) < i ) even then, the behaviour is same, this atleast I would personally disagree, since additional braces are provided, I expect the compiler to create a temporary built-in type variable and them compare, thus nullify the optimisation. Question 3 Suppose I have a huge code base, an I migrate my compiler version, such bug/optimisation can cause havoc in my system behaviour. Ofcourse from business perspective, it is very ineffective to test all lines of code again just because of compiler upgradation. I think for all practical purpose, these kinds of error are very difficult to catch (during upgradation) and invariably will be leaked to production site. Can anyone suggest any possible way to ensure to ensure that these kind of bug/optimization does not have any impact on my existing system/code base? PS : When the const for v is removed from the code, then optimization is not done by the compiler. I believe, it is perfectly fine to use overflow mechanism to find if the variable is from MAX - 50 value (in my case).

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• Design patterns and interview question

  - by user160758

  When I was learning to code, I read up on the design patterns like a good boy. Long after this, I started to actually understand them. Design discussions such as those on this site constantly try to make the rules more and more general, which is good. But there is a line, over which it becomes over-analysis starts to feed off itself and as such I think begins to obfuscate the original point - for example the "What's Alternative to Singleton" post and the links contained therein. http://stackoverflow.com/questions/1300655/whats-alternative-to-singleton I say this having been asked in both interviews I’ve had over the last 2 weeks what a singleton is and what criticisms I have of it. I have used it a few times for items such as user data (simple key-value eg. last file opened by this user) and logging (very common i'm sure). I've never ever used it just to have what is essentially global application data, as this is clearly stupid. In the first interview, I reply that I have no criticisms of it. He seemed disappointed by this but as the job wasn’t really for me, I forgot about it. In the next one, I was asked again and, as I wanted this job, I thought about it on the spot and made some objections, similar to those contained in the post linked to above (I suggested use of a factory or dependency injection instead). He seemed happy with this. But my problem is that I have used the singleton without ever using it in this kind of stupid way, which I had to describe on the spot. Using it for global data and the like isn’t something I did then realised was stupid, or read was stupid so didn’t do, it was just something I knew was stupid from the start. Essentially I’m supposed to be able to think of ways of how to misuse a pattern in the interview? Which class of programmers can best answer this question? The best ones? The medium ones? I'm not sure.... And these were both bright guys. I read more than enough to get better at my job but had never actually bothered to seek out criticisms of the most simple of the design patterns like this one. Do people think such questions are valid and that I ought to know the objections off by heart? Or that it is reasonable to be able to work out what other people who are missing the point would do on the fly? Or do you think I’m at least partially right that the question is too unsubtle and that the questions ought to be better thought out in order to make sure only good candidates can answer. PS. Please don’t think I’m saying that I’m just so clever that I know everything automatically - I’ve learnt the hard way like everyone else. But avoiding global data is hardly revolutionary.

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• Are there compelling reasons not to use Groovy?

  - by Leonard H Martin

  I'm developing a LoB application in Java after a long absence from the platform (having spent the last 8 years or so entrenched in Fortran, C, a smidgin of C++ and latterly .Net). Java, the language, is not much changed from how I remember it. I like it's strengths and I can work around its weaknesses - the platform has grown and deciding upon the myriad of different frameworks which appear to do much the same thing as one another is a different story; but that can wait for another day - all-in-all I'm comfortable with Java. However, over the last couple of weeks I've become enamoured with Groovy, and purely from a selfish point of view: but not just because it makes development against the JVM a more succinct and entertaining (and, well, "groovy") proposition than Java (the language). What strikes me most about Groovy is its inherent maintainability. We all (I hope!) strive to write well documented, easy to understand code. However, sometimes the languages we use themselves defeat us. An example: in 2001 I wrote a library in C to translate EDIFACT EDI messages into ANSI X12 messages. This is not a particularly complicated process, if slightly involved, and I thought at the time I had documented the code properly - and I probably had - but some six years later when I revisited the project (and after becoming acclimatised to C#) I found myself lost in so much C boilerplate (mallocs, pointers, etc. etc.) that it took three days of thoughtful analysis before I finally understood what I'd been doing six years previously. This evening I've written about 2000 lines of Java (it is the day of rest, after all!). I've documented as best as I know how, but, but, of those 2000 lines of Java a significant proportion is Java boiler plate. This is where I see Groovy and other dynamic languages winning through - maintainability and later comprehension. Groovy lets you concentrate on your intent without getting bogged down on the platform specific implementation; it's almost, but not quite, self documenting. I see this as being a huge boon to me when I revisit my current project (which I'll port to Groovy asap) in several years time and to my successors who will inherit it and carry on the good work. So, are there any reasons not to use Groovy?

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• In R, how do you get the best fitting equation to a set of data?

  - by Matherion

  I'm not sure wether R can do this (I assume it can, but maybe that's just because I tend to assume that R can do anything :-)). What I need is to find the best fitting equation to describe a dataset. For example, if you have these points: df = data.frame(x = c(1, 5, 10, 25, 50, 100), y = c(100, 75, 50, 40, 30, 25)) How do you get the best fitting equation? I know that you can get the best fitting curve with: plot(loess(df$y ~ df$x)) But as I understood you can't extract the equation, see Loess Fit and Resulting Equation. When I try to build it myself (note, I'm not a mathematician, so this is probably not the ideal approach :-)), I end up with smth like: y.predicted = 12.71 + ( 95 / (( (1 + df$x) ^ .5 ) / 1.3)) Which kind of seems to approximate it - but I can't help to think that smth more elegant probably exists :-) I have the feeling that fitting a linear or polynomial model also wouldn't work, because the formula seems different from what those models generally use (i.e. this one seems to need divisions, powers, etc). For example, the approach in Fitting polynomial model to data in R gives pretty bad approximations. I remember from a long time ago that there exist languages (Matlab may be one of them?) that do this kind of stuff. Can R do this as well, or am I just at the wrong place? (Background info: basically, what we need to do is find an equation for determining numbers in the second column based on the numbers in the first column; but we decide the numbers ourselves. We have an idea of how we want the curve to look like, but we can adjust these numbers to an equation if we get a better fit. It's about the pricing for a product (a cheaper alternative to current expensive software for qualitative data analysis); the more 'project credits' you buy, the cheaper it should become. Rather than forcing people to buy a given number (i.e. 5 or 10 or 25), it would be nicer to have a formula so people can buy exactly what they need - but of course this requires a formula. We have an idea for some prices we think are ok, but now we need to translate this into an equation.

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• What are the rules governing how a bind variable can be used in Postgres and where is this defined?

  - by Craig Miles

  I can have a table and function defined as: CREATE TABLE mytable ( mycol integer ); INSERT INTO mytable VALUES (1); CREATE OR REPLACE FUNCTION myfunction (l_myvar integer) RETURNS mytable AS $$ DECLARE l_myrow mytable; BEGIN SELECT * INTO l_myrow FROM mytable WHERE mycol = l_myvar; RETURN l_myrow; END; $$ LANGUAGE plpgsql; In this case l_myvar acts as a bind variable for the value passed when I call: SELECT * FROM myfunction(1); and returns the row where mycol = 1 If I redefine the function as: CREATE OR REPLACE FUNCTION myfunction (l_myvar integer) RETURNS mytable AS $$ DECLARE l_myrow mytable; BEGIN SELECT * INTO l_myrow FROM mytable WHERE mycol IN (l_myvar); RETURN l_myrow; END; $$ LANGUAGE plpgsql; SELECT * FROM myfunction(1); still returns the row where mycol = 1 However, if I now change the function definition to allow me to pass an integer array and try to this array in the IN clause, I get an error: CREATE OR REPLACE FUNCTION myfunction (l_myvar integer[]) RETURNS mytable AS $$ DECLARE l_myrow mytable; BEGIN SELECT * INTO l_myrow FROM mytable WHERE mycol IN (array_to_string(l_myvar, ',')); RETURN l_myrow; END; $$ LANGUAGE plpgsql; Analysis reveals that although: SELECT array_to_string(ARRAY[1, 2], ','); returns 1,2 as expected SELECT * FROM myfunction(ARRAY[1, 2]); returns the error operator does not exist: integer = text at the line: WHERE mycol IN (array_to_string(l_myvar, ',')); If I execute: SELECT * FROM mytable WHERE mycol IN (1,2); I get the expected result. Given that array_to_string(l_myvar, ',') evaluates to 1,2 as shown, why arent these statements equivalent. From the error message it is something to do with datatypes, but doesnt the IN(variable) construct appear to be behaving differently from the = variable construct? What are the rules here? I know that I could build a statement to EXECUTE, treating everything as a string, to achieve what I want to do, so I am not looking for that as a solution. I do want to understand though what is going on in this example. Is there a modification to this approach to make it work, the particular example being to pass in an array of values to build a dynamic IN clause without resorting to EXECUTE? Thanks in advance Craig

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• Is throwing an exception a healthy way to exit?

  - by ramaseshan

  I have a setup that looks like this. class Checker { // member data Results m_results; // see below public: bool Check(); private: bool Check1(); bool Check2(); // .. so on }; Checker is a class that performs lengthy check computations for engineering analysis. Each type of check has a resultant double that the checker stores. (see below) bool Checker::Check() { // initilisations etc. Check1(); Check2(); // ... so on } A typical Check function would look like this: bool Checker::Check1() { double result; // lots of code m_results.SetCheck1Result(result); } And the results class looks something like this: class Results { double m_check1Result; double m_check2Result; // ... public: void SetCheck1Result(double d); double GetOverallResult() { return max(m_check1Result, m_check2Result, ...); } }; Note: all code is oversimplified. The Checker and Result classes were initially written to perform all checks and return an overall double result. There is now a new requirement where I only need to know if any of the results exceeds 1. If it does, subsequent checks need not be carried out(it's an optimisation). To achieve this, I could either: Modify every CheckN function to keep check for result and return. The parent Check function would keep checking m_results. OR In the Results::SetCheckNResults(), throw an exception if the value exceeds 1 and catch it at the end of Checker::Check(). The first is tedious, error prone and sub-optimal because every CheckN function further branches out into sub-checks etc. The second is non-intrusive and quick. One disadvantage is I can think of is that the Checker code may not necessarily be exception-safe(although there is no other exception being thrown anywhere else). Is there anything else that's obvious that I'm overlooking? What about the cost of throwing exceptions and stack unwinding? Is there a better 3rd option?

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• How to ensure structures are completly initialized (by name) in GCC?

  - by Steven Spark

  How do I ensure each and every field of my structures are initialized in GCC when using designated initializers? (I'm especially interested in function pointers.) (I'm using C not C++.) Here is an example: typedef struct { int a; int b; } foo_t; typedef struct { void (*Start)(void); void (*Stop)(void); } bar_t; foo_t fooo = { 5 }; foo_t food = { .b=4 }; bar_t baro = { NULL }; bar_t bard = { .Start = NULL }; -Wmissing-field-initializers does not help at all. It works for fooo only in GCC (mingw 4.7.3, 4.8.1), and clang does only marginally better (no warnings for food and bard). I'm sure there is a reason for not producing warnings for designated initializer (even when I explicitly ask for them) but I want/need them. I do not want to initialize structures based on order/position because that is more error prone (for example swapping Start and Stop won't even give any warning). And neither gcc nor clang will give any warning that I failed to explicitly initialize a field (when initializing by name). I also don't want to litter my code with if(x.y==NULL) lines for multiple reasons, one of which is I want compile time warnings and not runtime errors. At least splint will give me warnings on all 4 cases, but unfortunately I cannot use splint all the time (it chokes on some of the code (fails to parse some C99, GCC extensions)). Note: If I'm using a real function instead of NULL GCC will also show a warning for baro (but not bard). I searched google and stack overflow but only found related questions and have not found answer for this specific problem. The best match I have found is 'Ensure that all elements in a structure are initialized' Ensure that all elements in a structure are initialized Which asks pretty much the same question, but has no satisfying answer. Is there a better way dealing with this that I have not mentioned? (Maybe other code analysis tool? Preferably something (free) that can be integrated into Eclipse or Visual Studio...)

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• HP SmartArray P400: How to repair failed logical drive?

  - by TegtmeierDE

  I have a HP Server with SmartArray P400 controller (incl. 256 MB Cache/Battery Backup) with a logicaldrive with replaced failed physicaldrive that does not rebuild. This is how it looked when I detected the error: ~# /usr/sbin/hpacucli ctrl slot=0 show config Smart Array P400 in Slot 0 (Embedded) (sn: XXXX) array A (SATA, Unused Space: 0 MB) logicaldrive 1 (698.6 GB, RAID 1, OK) physicaldrive 1I:1:1 (port 1I:box 1:bay 1, SATA, 750 GB, OK) physicaldrive 1I:1:2 (port 1I:box 1:bay 2, SATA, 750 GB, OK) array B (SATA, Unused Space: 0 MB) logicaldrive 2 (2.7 TB, RAID 5, Failed) physicaldrive 1I:1:3 (port 1I:box 1:bay 3, SATA, 750 GB, OK) physicaldrive 1I:1:4 (port 1I:box 1:bay 4, SATA, 750 GB, OK) physicaldrive 2I:1:5 (port 2I:box 1:bay 5, SATA, 750 GB, OK) physicaldrive 2I:1:6 (port 2I:box 1:bay 6, SATA, 750 GB, Failed) physicaldrive 2I:1:7 (port 2I:box 1:bay 7, SATA, 750 GB, OK) unassigned physicaldrive 2I:1:8 (port 2I:box 1:bay 8, SATA, 750 GB, OK) ~# I thought that I had drive 2I:1:8 configured as a spare for Array A and Array B, but it seems this was not the case :-(. I noticed the problem due to I/O errors on the host, even if only 1 physicaldrive of the RAID5 is failed. Does someone know why this could happen? The logicaldrive should go into "Degraded" mode but still be fully accessible from the host os!? I first tried to add the unassigned drive 2I:1:8 as a spare to logicaldrive 2, but this was not possible: ~# /usr/sbin/hpacucli ctrl slot=0 array B add spares=2I:1:8 Error: This operation is not supported with the current configuration. Use the "show" command on devices to show additional details about the configuration. ~# Interestingly it is possible to add the unassigned drive to the first array without problems. I thought maybe the controller put the array into "failed" state due to the missing spare and protects failed arrays from modification. So I tried was to reenable the logicaldrive (to add the spare afterwards): ~# /usr/sbin/hpacucli ctrl slot=0 ld 2 modify reenable Warning: Any previously existing data on the logical drive may not be valid or recoverable. Continue? (y/n) y Error: This operation is not supported with the current configuration. Use the "show" command on devices to show additional details about the configuration. ~# But as you can see, re-enabling the logicaldrive this was not possible. Now I replaced the failed drive by hotswapping it with the unassigned drive. The status now looks like this: ~# /usr/sbin/hpacucli ctrl slot=0 show config Smart Array P400 in Slot 0 (Embedded) (sn: XXXX) array A (SATA, Unused Space: 0 MB) logicaldrive 1 (698.6 GB, RAID 1, OK) physicaldrive 1I:1:1 (port 1I:box 1:bay 1, SATA, 750 GB, OK) physicaldrive 1I:1:2 (port 1I:box 1:bay 2, SATA, 750 GB, OK) array B (SATA, Unused Space: 0 MB) logicaldrive 2 (2.7 TB, RAID 5, Failed) physicaldrive 1I:1:3 (port 1I:box 1:bay 3, SATA, 750 GB, OK) physicaldrive 1I:1:4 (port 1I:box 1:bay 4, SATA, 750 GB, OK) physicaldrive 2I:1:5 (port 2I:box 1:bay 5, SATA, 750 GB, OK) physicaldrive 2I:1:6 (port 2I:box 1:bay 6, SATA, 750 GB, OK) physicaldrive 2I:1:7 (port 2I:box 1:bay 7, SATA, 750 GB, OK) ~# The logical drive is still not accessible. Why is it not rebuilding? What can I do? FYI, this is the configuration of my controller: ~# /usr/sbin/hpacucli ctrl slot=0 show Smart Array P400 in Slot 0 (Embedded) Bus Interface: PCI Slot: 0 Serial Number: XXXX Cache Serial Number: XXXX RAID 6 (ADG) Status: Enabled Controller Status: OK Chassis Slot: Hardware Revision: Rev E Firmware Version: 5.22 Rebuild Priority: Medium Expand Priority: Medium Surface Scan Delay: 15 secs Surface Analysis Inconsistency Notification: Disabled Raid1 Write Buffering: Disabled Post Prompt Timeout: 0 secs Cache Board Present: True Cache Status: OK Accelerator Ratio: 25% Read / 75% Write Drive Write Cache: Disabled Total Cache Size: 256 MB No-Battery Write Cache: Disabled Cache Backup Power Source: Batteries Battery/Capacitor Count: 1 Battery/Capacitor Status: OK SATA NCQ Supported: True ~# Thanks for you help in advance.

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• svnstat script

  - by Kyle Hodgson

  So I'm building out a shell script to check out all of our relevant svn repositories for analysis in svnstat. I've gotten all of this to work manually, now I'm writing up a bash script in cygwin on my Vista laptop, as I intend to move this to a Linux server at some point. Edit: I gave up on this and wrote a simple .bat script. I'll figure out the Linux deployment some other way. Edit: added the sleep 30 and svn log commands. I can tell now, with the svn log command, that it's not getting to the svn log ... this time, it did Applications, and ran the log, and then check out Database, and froze. I'll put the sleep 30 before and after the log this time. co2.sh #!/bin/bash function checkout { mkdir $1 svn checkout svn://dev-server/$1 $1 svn log --verbose --xml >> svn.log $1 sleep 30 } cd /cygdrive/c/Users/My\ User/Documents/Repos/wc checkout Applications checkout Database checkout WebServer/www.mysite.com checkout WebServer/anotherhost.mysite.com checkout WebServer/AnotherApp checkout WebServer/thirdhost.mysite.com checkout WebServer/fourthhost.mysite.com checkout WebServer/WebServices It works, for the most part - but for some reason it has a tendency to stop working after a few repositories, usually right after finishing a repository before going to the next one. When it fails, it will not recover on its own. I've tried commenting out the svn line, it goes in and creates all the directories just fine when I do that - so its not that. I'm looking for direction as well as direct advice. Cygwin has been very stable for me, but I did start using the native rxvt instead of "bash in a cmd.exe window" recently. I don't think that's the problem, as I've left top on remote systems running all night and rxvt didn't seem to mind. Also I haven't done any bash scripting in cygwin so I suppose this might not be recommended; though I can't see why not. I don't want all of WebServer, hence me only checking out certain folders like that. What I suspect is that something is hanging up the svn checkout. Any ideas here? Edit: this time when I hit ctrl+z to cancel out, I forgot I was on Windows and typed ps to see if the job was still running; and as you can see there are lots of svn processes hanging around... strange. Kyle Hodgson@KyleHodgson-PC ~/winUser/Documents/Repos $ Kyle Hodgson@KyleHodgson-PC ~/winUser/Documents/Repos $ jobs [1]- Stopped bash co2.sh [2]+ Stopped ./co2.sh Kyle Hodgson@KyleHodgson-PC ~/winUser/Documents/Repos $ kill %1 [1]- Stopped bash co2.sh Kyle Hodgson@KyleHodgson-PC ~/winUser/Documents/Repos $ [1]- Terminated bash co2.sh Kyle Hodgson@KyleHodgson-PC ~/winUser/Documents/Repos $ Kyle Hodgson@KyleHodgson-PC ~/winUser/Documents/Repos $ Kyle Hodgson@KyleHodgson-PC ~/winUser/Documents/Repos $ ps PID PPID PGID WINPID TTY UID STIME COMMAND 7872 1 7872 2340 0 1000 Jun 29 /usr/bin/svn 7752 1 6140 7828 1 1000 Jun 29 /usr/bin/svn 6192 1 5044 2192 1 1000 Jun 30 /usr/bin/svn 7292 1 7452 1796 1 1000 Jun 30 /usr/bin/svn 6236 1 7304 7468 2 1000 Jul 2 /usr/bin/svn 1564 1 5032 7144 2 1000 Jul 2 /usr/bin/svn 9072 1 3960 6276 3 1000 Jul 3 /usr/bin/svn 5876 1 5876 5876 con 1000 11:22:10 /usr/bin/rxvt 924 5876 924 10192 4 1000 11:22:10 /usr/bin/bash 7212 1 7332 5584 4 1000 13:17:54 /usr/bin/svn 9412 1 5480 8840 4 1000 15:38:16 /usr/bin/svn S 8128 924 8128 9452 4 1000 17:38:05 /usr/bin/bash 9132 8128 8128 8172 4 1000 17:43:25 /usr/bin/svn 3512 1 3512 3512 con 1000 17:43:50 /usr/bin/rxvt I 10200 3512 10200 6616 5 1000 17:43:51 /usr/bin/bash 9732 1 9732 9732 con 1000 17:45:55 /usr/bin/rxvt 3148 9732 3148 8976 6 1000 17:45:55 /usr/bin/bash 5856 3148 5856 876 6 1000 17:51:00 /usr/bin/vim 7736 924 7736 8036 4 1000 17:53:26 /usr/bin/ps Kyle Hodgson@KyleHodgson-PC ~/winUser/Documents/Repos $ jobs [2]+ Stopped ./co2.sh Kyle Hodgson@KyleHodgson-PC ~/winUser/Documents/Repos $ Here's an strace on the PID of the hung svn program, it's been like this for hours. Looks like its just doing nothing. I keep suspecting that some interruption on the server is causing this; does svn have a locking mechanism I'm not aware of? Kyle Hodgson@KyleHodgson-PC ~/winUser/Documents/Repos $ strace -p 7304 ********************************************** Program name: C:\cygwin\bin\svn.exe (pid 7304, ppid 6408) App version: 1005.25, api: 0.156 DLL version: 1005.25, api: 0.156 DLL build: 2008-06-12 19:34 OS version: Windows NT-6.0 Heap size: 402653184 Date/Time: 2009-07-06 18:20:11 **********************************************

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• How do you handle authentication across domains?

  - by William Ratcliff

  I'm trying to save users of our services from having to have multiple accounts/passwords. I'm in a large organization and there's one group that handles part of user authentication for users who are from outside the facility (primarily for administrative functions). They store a secure cookie to establish a session and communicate only via HTTPS via the browser. Sessions expire either through: 1) explicit logout of the user 2) Inactivity 3) Browser closes My team is trying to write a web application to help users analyze data that they've taken (or are currently taking) while at our facility. We need to determine if a user is 1) authenticated 2) Some identifier for that user so we can store state for them (what analysis they are working on, etc.) So, the problem is how do you authenticate across domains (the authentication server for the other application lives in a border region between public and private--we will live in the public region). We have come up with some scenarios and I'd like advice about what is best practice, or if there is one we haven't considered. Let's start with the case where the user is authenticated with the authentication server. 1) The authentication server leaves a public cookie in the browser with their primary key for a user. If this is deemed sensitive, they encrypt it on their server and we have the key to decrypt it on our server. When the user visits our site, we check for this public cookie. We extract the user_id and use a public api for the authentication server to request if the user is logged in. If they are, they send us a response with: response={ userid :we can then map this to our own user ids. If necessary, we can request additional information such as email-address/display name once (to notify them if long running jobs are done, or to share results with other people, like with google_docs). account_is_active:Make sure that the account is still valid session_is_active: Is their session still active? If we query this for a valid user, this will have a side effect that we will reset the last_time_session_activated value and thus prolong their session with the authentication server last_time_session_activated: let us know how much time they have left ip_address_session_started_from:make sure the person at our site is coming from the same ip as they started the session at } Given this response, we either accept them as authenticated and move on with our app, or redirect them to the login page for the authentication server (question: if we give an encrypted portion of the response (signed by us) with the page to redirect them to, do we open any gaping security holes in the authentication server)? The flaw that we've found with this is that if the user visits evilsite.com and they look at the session cookie and send a query to the public api of the authentication server, they can keep the session alive and if our original user leaves the machine without logging out, then the next user will be able to access their session (this was possible before, but having the session alive eternally makes this worse). 2) The authentication server redirects all requests made to our domain to us and we send responses back through them to the user. Essentially, they act as a proxy. The advantage of this is that we can handshake with the authentication server, so it's safe to be trusted with the email address/name of the user and they don't have to reenter it So, if the user tries to go to: authentication_site/mysite_page1 they are redirected to mysite. Which would you choose, or is there a better way? The goal is to minimize the "Yet Another Password/Yet another username" problem... Thanks!!!!

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• creating a heirarchy of terminals or workspaces

  - by intuited

  <rant This question occurred to me ('occurred' meaning 'whispered seductively in my ear for the 100th time') while using GNU-screen, so I'll make that my example. However this is a much more general question about user interfaces and what I perceive as a flawmissing feature in every implementation I've yet seen. I'm wondering if there is some way to create a heirarchy/tree of terminals in a screen session. EG I'd like to have something like 1 bash 1.1 bash 1.2 bash 2 bash 3 bash 3.1 bash 3.1.1 bash 3.1.2 bash It would be good if the terminals could be labelled instead of having to be navigated to via some arrangement that I suspect doesn't exist. So then you could jump to one using eg ^A:goto happydays or ^A:goto dykstra.angry. So to generalize that: Firefox, Chrome, Internet Explorer, gnome-terminal, roxterm, konsole, yakuake, OpenOffice, Microsoft Office, Mr. Snuffaluppagus's Funtime Carousel™, and Your Mom's Jam Browser™ all offer the ability to create a flat set of tabs containing documents of an identical nature: web pages, terminals, documents, fun rideable animals, and jams. GNU-screen implements the same functionality without using tabs. Linux and OS/X window managers provide the ability to organize windows into an array of workspaces, which amounts to again, the same deal. Over the past few years, this has become a more or less ubiquitous concept which has been righteously welcomed into the far reaches of the computer interface funfest. Heavy users of these systems quickly encounter a problem with it: the set of entities is flat. In the case of workspaces, an option may be available to create a 2d array. However none of these applications furnish their users with the ability to create heirarchies, similar to filesystem directory structures, containing instances of their particular contained type. I for one am consistently bothered by this, and am wondering if the community can offer some wisdom as to why this has not happened in any of the foremost collections of computational functionality our culture has yet produced. Or if perhaps it has and I'm just an ignorant savage. I'd like to be able to not only group things into a tree structure, but also to create references (aka symbolic links, aka pointers) from one part of the structure to another, as well as apply properties (eg default directory, colorscheme, ...) recursively downward from a given node. I see no reason why we shouldn't be able to save these structures as known sessions, and apply tags to particular instances. So then you can sort through them by tag, find them by name, or just use the arrow keys (with an appropriate modifier) to move left or right and in or out of a given level. Another key combo would serve to create a branch in the place of the current terminal/webpage/lifelike statue/spreadsheet/spreadsheet sheet/presentation/jam and move that entity into the new branch, then create a fresh one as a sibling to it: a second leaf node within the same branch node. They would get along well. I find it a bit astonishing that this hasn't happened yet, and the only reason I can venture as a guess is that the creators of these fine systems do not consider such functionality to be useful to a significant portion of their userbase. I posit that the probability that that such an assumption would be correct is pretty low. On the other hand, given the relative ease with which such structures can be implemented using modern libraries/languages, it doesn't seem likely that difficulty of implementation would be a major roadblock. If it could be done in 1972 or whenever within the constraints of a filesystem driver, it should be relatively painless to implement in 2010 in a fullblown application. Given that all of these systems are capable of maintaining a set of equivalent entities, it seems unlikely that a major infrastructure overhaul would be necessary in order to enable a navigable heirarchy of them. </rant Mostly I'm just looking to start up a discussion and/or brainstorming on this topic. Any ideas, examples, criticism, or analysis are quite welcome. * Mr. Snuffaluppagus's Funtime Carousel is a registered trademark of Children's Television Workshop Inc. * Your Mom's Jam Browser is a registered trademark of Your Mom Inc.

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• Windows 7 BSOD - ntoskrnl?

  - by Ken Mason

  2 new HP Pavilion notebooks with 7 Home Premium pre-loaded with Norton. My first act was to use the Norton Removal Tool and load ZoneAlarm free and AVG Free. Frequent random BSOD's ever since...I found my way into Debug and have had various reports regarding ntoskrnl, depending on the status of symbols. It's been many years since I played with (DOS 3.x) debug, so this has been a considerable fumble. Excerpts follow and any insights would be greatly appreciated, as I am not a developer: ADDITIONAL_DEBUG_TEXT: Use '!findthebuild' command to search for the target build information. If the build information is available, run '!findthebuild -s ; .reload' to set symbol path and load symbols. MODULE_NAME: nt FAULTING_MODULE: fffff8000305d000 nt DEBUG_FLR_IMAGE_TIMESTAMP: 4b88cfeb BUGCHECK_STR: 0x7f_8 CUSTOMER_CRASH_COUNT: 1 DEFAULT_BUCKET_ID: VISTA_DRIVER_FAULT CURRENT_IRQL: 0 LAST_CONTROL_TRANSFER: from fffff800030ccb69 to fffff800030cd600 STACK_TEXT: fffff80004d6fd28 fffff800030ccb69 : 000000000000007f 0000000000000008 0000000080050033 00000000000006f8 : nt+0x70600 fffff80004d6fd30 000000000000007f : 0000000000000008 0000000080050033 00000000000006f8 fffff80003095e58 : nt+0x6fb69 fffff80004d6fd38 0000000000000008 : 0000000080050033 00000000000006f8 fffff80003095e58 0000000000000000 : 0x7f fffff80004d6fd40 0000000080050033 : 00000000000006f8 fffff80003095e58 0000000000000000 0000000000000000 : 0x8 fffff80004d6fd48 00000000000006f8 : fffff80003095e58 0000000000000000 0000000000000000 0000000000000000 : 0x80050033 fffff80004d6fd50 fffff80003095e58 : 0000000000000000 0000000000000000 0000000000000000 0000000000000000 : 0x6f8 fffff80004d6fd58 0000000000000000 : 0000000000000000 0000000000000000 0000000000000000 0000000000000000 : nt+0x38e58 STACK_COMMAND: kb FOLLOWUP_IP: nt+70600 fffff800`030cd600 48894c2408 mov qword ptr [rsp+8],rcx SYMBOL_STACK_INDEX: 0 SYMBOL_NAME: nt+70600 FOLLOWUP_NAME: MachineOwner IMAGE_NAME: ntoskrnl.exe BUCKET_ID: WRONG_SYMBOLS Followup: MachineOwner ...................................................................... 0: kd !lmi nt Loaded Module Info: [nt] Module: ntkrnlmp Base Address: fffff8000305d000 Image Name: ntkrnlmp.exe Machine Type: 34404 (X64) Time Stamp: 4b88cfeb Sat Feb 27 00:55:23 2010 Size: 5dc000 CheckSum: 545094 Characteristics: 22 perf Debug Data Dirs: Type Size VA Pointer CODEVIEW 25, 19c65c, 19bc5c RSDS - GUID: {7E9A3CAB-6268-45DE-8E10-816E3080A3B7} Age: 2, Pdb: ntkrnlmp.pdb CLSID 4, 19c658, 19bc58 [Data not mapped] Image Type: FILE - Image read successfully from debugger. ntkrnlmp.exe Symbol Type: PDB - Symbols loaded successfully from symbol server. d:\debugsymbols\ntkrnlmp.pdb\7E9A3CAB626845DE8E10816E3080A3B72\ntkrnlmp.pdb Load Report: public symbols , not source indexed d:\debugsymbols\ntkrnlmp.pdb\7E9A3CAB626845DE8E10816E3080A3B72\ntkrnlmp.pdb 0: kd !analyze -v * Bugcheck Analysis * * UNEXPECTED_KERNEL_MODE_TRAP (7f) This means a trap occurred in kernel mode, and it's a trap of a kind that the kernel isn't allowed to have/catch (bound trap) or that is always instant death (double fault). The first number in the bugcheck params is the number of the trap (8 = double fault, etc) Consult an Intel x86 family manual to learn more about what these traps are. Here is a portion of those codes: If kv shows a taskGate use .tss on the part before the colon, then kv. Else if kv shows a trapframe use .trap on that value Else .trap on the appropriate frame will show where the trap was taken (on x86, this will be the ebp that goes with the procedure KiTrap) Endif kb will then show the corrected stack. Arguments: Arg1: 0000000000000008, EXCEPTION_DOUBLE_FAULT Arg2: 0000000080050033 Arg3: 00000000000006f8 Arg4: fffff80003095e58 Debugging Details: BUGCHECK_STR: 0x7f_8 CUSTOMER_CRASH_COUNT: 1 DEFAULT_BUCKET_ID: VISTA_DRIVER_FAULT PROCESS_NAME: System CURRENT_IRQL: 2 LAST_CONTROL_TRANSFER: from fffff800030ccb69 to fffff800030cd600 STACK_TEXT: fffff80004d6fd28 fffff800030ccb69 : 000000000000007f 0000000000000008 0000000080050033 00000000000006f8 : nt!KeBugCheckEx fffff80004d6fd30 fffff800030cb032 : 0000000000000000 0000000000000000 0000000000000000 0000000000000000 : nt!KiBugCheckDispatch+0x69 fffff80004d6fe70 fffff80003095e58 : 0000000000000000 0000000000000000 0000000000000000 0000000000000000 : nt!KiDoubleFaultAbort+0xb2 fffff880089efc60 0000000000000000 : 0000000000000000 0000000000000000 0000000000000000 0000000000000000 : nt!SeAccessCheckFromState+0x58 STACK_COMMAND: kb FOLLOWUP_IP: nt!KiDoubleFaultAbort+b2 fffff800`030cb032 90 nop SYMBOL_STACK_INDEX: 2 SYMBOL_NAME: nt!KiDoubleFaultAbort+b2 FOLLOWUP_NAME: MachineOwner MODULE_NAME: nt IMAGE_NAME: ntkrnlmp.exe DEBUG_FLR_IMAGE_TIMESTAMP: 4b88cfeb FAILURE_BUCKET_ID: X64_0x7f_8_nt!KiDoubleFaultAbort+b2 BUCKET_ID: X64_0x7f_8_nt!KiDoubleFaultAbort+b2 Followup: MachineOwner I tried running Rootkit Revealer but I don't think it works on x64 systems. Similarly Blacklight seems to have aged off. I'm running Sophos Anti-Rootkit now. So far so good...

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• Expert iptables help needed?

  - by Asad Moeen

  After a detailed analysis, I collected these details. I am under a UDP Flood which is more of application dependent. I run a Game-Server and an attacker is flooding me with "getstatus" query which makes the GameServer respond by making the replies to the query which cause output to the attacker's IP as high as 30mb/s and server lag. Here are the packet details, Packet starts with 4 bytes 0xff and then getstatus. Theoretically, the packet is like "\xff\xff\xff\xffgetstatus " Now that I've tried a lot of iptables variations like state and rate-limiting along side but those didn't work. Rate Limit works good but only when the Server is not started. As soon as the server starts, no iptables rule seems to block it. Anyone else got more solutions? someone asked me to contact the provider and get it done at the Network/Router but that looks very odd and I believe they might not do it since that would also affect other clients. Responding to all those answers, I'd say: Firstly, its a VPS so they can't do it for me. Secondly, I don't care if something is coming in but since its application generated so there has to be a OS level solution to block the outgoing packets. At least the outgoing ones must be stopped. Secondly, its not Ddos since just 400kb/s input generates 30mb/s output from my GameServer. That never happens in a D-dos. Asking the provider/hardware level solution should be used in that case but this one is different. And Yes, Banning his IP stops the flood of outgoing packets but he has many more IP-Addresses as he spoofs his original so I just need something to block him automatically. Even tried a lot of Firewalls but as you know they are just front-ends to iptables so if something doesn't work on iptables, what would the firewalls do? These were the rules I tried, iptables -A INPUT -p udp -m state --state NEW -m recent --set --name DDOS --rsource iptables -A INPUT -p udp -m state --state NEW -m recent --update --seconds 1 --hitcount 5 --name DDOS --rsource -j DROP It works for the attacks on un-used ports but when the server is listening and responding to the incoming queries by the attacker, it never works. Okay Tom.H, your rules were working when I modified them somehow like this: iptables -A INPUT -p udp -m length --length 1:1024 -m recent --set --name XXXX --rsource iptables -A INPUT -p udp -m string --string "xxxxxxxxxx" --algo bm --to 65535 -m recent --update --seconds 1 --hitcount 15 --name XXXX --rsource -j DROP They worked for about 3 days very good where the string "xxxxxxxxx" would be rate-limited, blocked if someone flooded and also didn't affect the clients. But just today, I tried updating the chain to try to remove a previously blocked IP so for that I had to flush the chain and restore this rule ( iptables -X and iptables -F ), some clients were already connected to servers including me. So restoring the rules now would also block some of the clients string completely while some are not affected. So does this mean I need to restart the server or why else would this happen because the last time the rules were working, there was no one connected?

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• Why are my httpd mpm_prefork processes being reaped so quickly?

  - by Dan Pritts

  We've got a system running RHEL6, x64. We are using a local installation of apache 2.2.22 from source. we serve primarily: mod_perl applications (with a local installation of perl 5.16.0) tomcat applications proxied with mod_jk Here is some context; the main question is below. All of this talks to an Oracle backend. We are having issues with Oracle becoming unresponsive. We think this is because we're hitting the maximum process limit in oracle. We've upped the process limit, but now we are hitting memory pressure on the oracle server. We have tons of oracle sessions sitting idle. I can trace a bunch of them back to the httpd processes. We have mod_perl's Apache::DBI start up a new connection to the database with each httpd child that's spawned. We are concerned that these are not always getting closed out properly when the httpd's exit...and the httpd's are exiting very frequently. I know that it would be good to modify the mod_perl applications to use some better form of db connection pooling; we plan to pursue that but would like to solve our immediate problem sooner. So here's the main question. We are using the prefork MPM. The apache child processes are lasting at most a few minutes. Log analysis shows that each one is serving fewer than 50 clients before exiting; the last request each child serves is OPTIONS * HTTP/1.0 on some sort of internal connection; I'm under the impression that this is a "ping" from the master process. I've adjusted the MPM config as follows. I didn't want to raise MinSpareServers too high, because, after all, i'm trying to minimize the number of sessions to oracle. MinSpareServers 5 MaxSpareServers 30 MaxClients 150 MaxRequestsPerChild 10000 Right now we're serving 250-300 requests per minute. We've got 21 httpd's running, the eldest (other than the master, owned by root) being 3 minutes old. This rate of reaping of the apache children really seems excessive. What could be causing it? Apache was built with: $ ./configure --prefix=/opt/apache --with-ssl=/usr/lib --enable-expires --enable-ext-filter --enable-info --enable-mime-magic --enable-rewrite --enable-so --enable-speling --enable-ssl --enable-usertrack --enable-proxy --enable-headers --enable-log-forensic Apache config info: % /opt/apache/bin/httpd -V Server version: Apache/2.2.22 (Unix) Server built: Jul 23 2012 22:30:13 Server's Module Magic Number: 20051115:30 Server loaded: APR 1.4.5, APR-Util 1.4.1 Compiled using: APR 1.4.5, APR-Util 1.4.1 Architecture: 64-bit Server MPM: Prefork threaded: no forked: yes (variable process count) Server compiled with.... -D APACHE_MPM_DIR="server/mpm/prefork" -D APR_HAS_SENDFILE -D APR_HAS_MMAP -D APR_HAVE_IPV6 (IPv4-mapped addresses enabled) -D APR_USE_SYSVSEM_SERIALIZE -D APR_USE_PTHREAD_SERIALIZE -D SINGLE_LISTEN_UNSERIALIZED_ACCEPT -D APR_HAS_OTHER_CHILD -D AP_HAVE_RELIABLE_PIPED_LOGS -D DYNAMIC_MODULE_LIMIT=128 -D HTTPD_ROOT="/opt/apache" -D SUEXEC_BIN="/opt/apache/bin/suexec" -D DEFAULT_PIDLOG="logs/httpd.pid" -D DEFAULT_SCOREBOARD="logs/apache_runtime_status" -D DEFAULT_LOCKFILE="logs/accept.lock" -D DEFAULT_ERRORLOG="logs/error_log" -D AP_TYPES_CONFIG_FILE="conf/mime.types" -D SERVER_CONFIG_FILE="conf/httpd.conf" modules are compiled into apache rather than shared libs: % /opt/apache/bin/httpd -l Compiled in modules: core.c mod_authn_file.c mod_authn_default.c mod_authz_host.c mod_authz_groupfile.c mod_authz_user.c mod_authz_default.c mod_auth_basic.c mod_ext_filter.c mod_include.c mod_filter.c mod_log_config.c mod_log_forensic.c mod_env.c mod_mime_magic.c mod_expires.c mod_headers.c mod_usertrack.c mod_setenvif.c mod_version.c mod_proxy.c mod_proxy_connect.c mod_proxy_ftp.c mod_proxy_http.c mod_proxy_scgi.c mod_proxy_ajp.c mod_proxy_balancer.c mod_ssl.c prefork.c http_core.c mod_mime.c mod_status.c mod_autoindex.c mod_asis.c mod_info.c mod_cgi.c mod_negotiation.c mod_dir.c mod_actions.c mod_speling.c mod_userdir.c mod_alias.c mod_rewrite.c mod_so.c One final note - the red hat httpd, apr, and perl packages are all installed, but ldd shows that none of those libraries are linked with the running httpd.

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• Hardware recommendations / parts list for a modern, quiet ZFS NAS box - 2011-Feb edition [closed]

  - by dandv

  I want to build some really reliable storage for my data, and it seems that ZFS is the only filesystem at the moment that does live checksumming. That rules out DroboPro, so I'm looking to building a quiet ZFS NAS that would start with 4 2TB or larger hard drives. I'd like this system to be very reliable and relatively future-proof for 2-3 years, so I'm willing to invest some $$$ and buy higher end components. I did see questions here and on other forums about low-cost servers, but I'm not looking for those. I'd be super happy to go for an off-the-shelf solution, but I haven't found one that's quiet. I started doing the research (summarized on my wiki), but I realized that it just gets too complicated for what I know as a software dude, and I'm entering the analysis paralysis area. At this point, I'm basically looking for a parts list for a configuration that will work (and is modern), and I know there are folks around here who are way more competent than me. I've built computers and am comfortable assembling one and messing with *nix; I can follow guides; I just want to end the decision process for the hardware and software configuration. What I've researched so far (not that these are very modern components): Case: I think I've settled on the Antec Twelve Hundred case because it cools well, is quiet, and simply has 12 bays that allow elastic mounting. The SilverStone Raven is its counter-candidate, but I find its construction quite odd. For the PSU, I'm torn between Antec CP-850 and Nexus RX-8500, but I did this research more than a year ago. The Nexus has a very uniform power profile, and I'd rather not have the Antec spin up and down based on load. On the other hand, I'm not sure how often my file server will draw more than 400W under use. For the hard drives, I've read that WD Black drives are actually WD RE3 with a software setting changed. I'd also like to buy different drive types, not just 4 WDs. Recommendations? Right now I have a 2TB Hitachi Deskstar 7K300. For the motherboard, CPU and RAM I have no idea, other than the RAM must be ECC. I already asked a question here about ECC RAM, but I was misguided and was looking for a motherboard that would support USB 3.0 as well. I've learned to go with eSATA, or worry about USB later. Then there's the (liquid) cooling, Wi-Fi card, and FreeBSD vs. OpenSolaris Express. Lastly, I'm wondering if I can make this PC into a media server by adding a Blu-ray drive and a good sound card. But support for Blu-Ray is spotty on Linux, and I don't know if Windows 7 on VirtualBox would get sufficient hardware access to output HDMI or SPDIFF signals. (Running OpenSolaris virtualized is not an option because of the reliability risk.) Then there are HDCP concerns. Suggestions on that would be appreciated as well, but I don't want us to get sidetracked. A specific shopping list on the core components would be great, so I can start ordering, and in the meantime educate myself with regards to the other issues. Finally, I think this could become a great FAQ for those technically inclined to build their own ZFS server, but confused by the dizzying array of options out there, and I promise to compile the results and share my experience building and benchmarking the server.

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• Proliant server will not accept new hard disks in RAID 1+0?

  - by Leigh

  I have a HP ProLiant DL380 G5, I have two logical drives configured with RAID. I have one logical drive RAID 1+0 with two 72 gb 10k sas 1 port spare no 376597-001. I had one hard disk fail and ordered a replacement. The configuration utility showed error and would not rebuild the RAID. I presumed a hard disk fault and ordered a replacement again. In the mean time I put the original failed disk back in the server and this started rebuilding. Currently shows ok status however in the log I can see hardware errors. The new disk has come and I again have the same problem of not accepting the hard disk. I have updated the P400 controller with the latest firmware 7.24 , but still no luck. The only difference I can see is the original drive has firmware 0103 (same as the RAID drive) and the new one has HPD2. Any advice would be appreciated. Thanks in advance Logs from server ctrl all show config Smart Array P400 in Slot 1 (sn: PAFGK0P9VWO0UQ) array A (SAS, Unused Space: 0 MB) logicaldrive 1 (68.5 GB, RAID 1, Interim Recovery Mode) physicaldrive 2I:1:1 (port 2I:box 1:bay 1, SAS, 73.5 GB, OK) physicaldrive 2I:1:2 (port 2I:box 1:bay 2, SAS, 72 GB, Failed array B (SAS, Unused Space: 0 MB) logicaldrive 2 (558.7 GB, RAID 5, OK) physicaldrive 1I:1:5 (port 1I:box 1:bay 5, SAS, 300 GB, OK) physicaldrive 2I:1:3 (port 2I:box 1:bay 3, SAS, 300 GB, OK) physicaldrive 2I:1:4 (port 2I:box 1:bay 4, SAS, 300 GB, OK) ctrl all show config detail Smart Array P400 in Slot 1 Bus Interface: PCI Slot: 1 Serial Number: PAFGK0P9VWO0UQ Cache Serial Number: PA82C0J9VWL8I7 RAID 6 (ADG) Status: Disabled Controller Status: OK Hardware Revision: E Firmware Version: 7.24 Rebuild Priority: Medium Expand Priority: Medium Surface Scan Delay: 15 secs Surface Scan Mode: Idle Wait for Cache Room: Disabled Surface Analysis Inconsistency Notification: Disabled Post Prompt Timeout: 0 secs Cache Board Present: True Cache Status: OK Cache Status Details: A cache error was detected. Run more information. Cache Ratio: 100% Read / 0% Write Drive Write Cache: Disabled Total Cache Size: 256 MB Total Cache Memory Available: 208 MB No-Battery Write Cache: Disabled Battery/Capacitor Count: 0 SATA NCQ Supported: True Array: A Interface Type: SAS Unused Space: 0 MB Status: Failed Physical Drive Array Type: Data One of the drives on this array have failed or has Logical Drive: 1 Size: 68.5 GB Fault Tolerance: RAID 1 Heads: 255 Sectors Per Track: 32 Cylinders: 17594 Strip Size: 128 KB Full Stripe Size: 128 KB Status: Interim Recovery Mode Caching: Enabled Unique Identifier: 600508B10010503956574F305551 Disk Name: \\.\PhysicalDrive0 Mount Points: C:\ 68.5 GB Logical Drive Label: A0100539PAFGK0P9VWO0UQ0E93 Mirror Group 0: physicaldrive 2I:1:2 (port 2I:box 1:bay 2, S Mirror Group 1: physicaldrive 2I:1:1 (port 2I:box 1:bay 1, S Drive Type: Data physicaldrive 2I:1:1 Port: 2I Box: 1 Bay: 1 Status: OK Drive Type: Data Drive Interface Type: SAS Size: 73.5 GB Rotational Speed: 10000 Firmware Revision: 0103 Serial Number: B379P8C006RK Model: HP DG072A9B7 PHY Count: 2 PHY Transfer Rate: Unknown, Unknown physicaldrive 2I:1:2 Port: 2I Box: 1 Bay: 2 Status: Failed Drive Type: Data Drive Interface Type: SAS Size: 72 GB Rotational Speed: 15000 Firmware Revision: HPD9 Serial Number: D5A1PCA04SL01244 Model: HP EH0072FARUA PHY Count: 2 PHY Transfer Rate: Unknown, Unknown Array: B Interface Type: SAS Unused Space: 0 MB Status: OK Array Type: Data Logical Drive: 2 Size: 558.7 GB Fault Tolerance: RAID 5 Heads: 255 Sectors Per Track: 32 Cylinders: 65535 Strip Size: 64 KB Full Stripe Size: 128 KB Status: OK Caching: Enabled Parity Initialization Status: Initialization Co Unique Identifier: 600508B10010503956574F305551 Disk Name: \\.\PhysicalDrive1 Mount Points: E:\ 558.7 GB Logical Drive Label: AF14FD12PAFGK0P9VWO0UQD007 Drive Type: Data physicaldrive 1I:1:5 Port: 1I Box: 1 Bay: 5 Status: OK Drive Type: Data Drive Interface Type: SAS Size: 300 GB Rotational Speed: 10000 Firmware Revision: HPD4 Serial Number: 3SE07QH300009923X1X3 Model: HP DG0300BALVP Current Temperature (C): 32 Maximum Temperature (C): 45 PHY Count: 2 PHY Transfer Rate: Unknown, Unknown physicaldrive 2I:1:3 Port: 2I Box: 1 Bay: 3 Status: OK Drive Type: Data Drive Interface Type: SAS Size: 300 GB Rotational Speed: 10000 Firmware Revision: HPD4 Serial Number: 3SE0AHVH00009924P8F3 Model: HP DG0300BALVP Current Temperature (C): 34 Maximum Temperature (C): 47 PHY Count: 2 PHY Transfer Rate: Unknown, Unknown physicaldrive 2I:1:4 Port: 2I Box: 1 Bay: 4 Status: OK Drive Type: Data Drive Interface Type: SAS Size: 300 GB Rotational Speed: 10000 Firmware Revision: HPD4 Serial Number: 3SE08NAK00009924KWD6 Model: HP DG0300BALVP Current Temperature (C): 35 Maximum Temperature (C): 47 PHY Count: 2 PHY Transfer Rate: Unknown, Unknown

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• Using PHP to connect to RADIUS works on one server but not another

  - by JDS

  I have a fleet of webservers that server a LAMP webapp broken into multiple customer apps by virtualhost/domain. The platform is Ubuntu 10.04 VM + PHP 5.3 + Apache 2.2.14, on top of VMware ESX (v4 I think). This stuff's not too important, though -- I'm just setting up the background. I have one customer that connects to a RADIUS server for authentication. We've found that the app responds as if some number of web servers are configured correctly and some are not. i.e. Apparently random authentication failures or successes, with no rhyme or reason. I did a lot of analysis of our fleet, and resolved it down to the differences between two specific web servers. I'll call them "A" and "B". "A" works. "B" does not. "Works" means "connects to and gets authentication data successfully from the RADIUS server". Ultimately, I'm looking for one thing that is different, and I've exhausted everything that I can come up with, so, looking for something else. Here are things I've looked at PHP package versions (all from Ubuntu repos). These are exactly the same across servers. PECL package. There are no PECL packages that aren't installed by apt. Other libraries or packages. Nothing that was network-related or RADIUS-related was different among servers. (There were some minor package differences, though.) Network or hosting environment. I found that some of the working servers were on the same physical environment as some not-working ones (i.e. same ESX containers). So, probably, the physical network layer is not the problem. Test case. I created a test case as follows. It works on the working servers, and fails on the not-working servers, very consistently. <?php $radius = radius_auth_open(); $username = 'theusername'; $password = 'thepassword'; $hostname = '12.34.56.78'; $radius_secret = '39wmmvxghg'; if (! radius_add_server($radius,$hostname,0,$radius_secret,5,3)) { die('Radius Error 1: ' . radius_strerror($radius) . "\n"); } if (! radius_create_request($radius,RADIUS_ACCESS_REQUEST)) { die('Radius Error 2: ' . radius_strerror($radius) . "\n"); } radius_put_attr($radius,RADIUS_USER_NAME,$username); radius_put_attr($radius,RADIUS_USER_PASSWORD,$password); switch (radius_send_request($radius)) { case RADIUS_ACCESS_ACCEPT: echo 'GOOD LOGIN'; break; case RADIUS_ACCESS_REJECT: echo 'BAD LOGIN'; break; case RADIUS_ACCESS_CHALLENGE: echo 'CHALLENGE REQUESTED'; break; default: die('Radius Error 3: ' . radius_strerror($radius) . "\n"); } ?>

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• Trying to prevent Windows from hibernating/sleeping automatically

  - by user328821

  My Dell XPS 8700 (Win 7) suddenly began putting itself to sleep at 6pm daily, even if I'm typing. I don't know what caused this to occur, except possibly a windows update that took place in the middle of the night. I initially went into settings for power and saw 2 plans set up, one from Dell and the other window's Power saver plan. I set both to never for sleep and hibernate yet it still occurred. I have current drivers and a fairly new UPS that has software to set to shutdown only after power loss. Dell is of little help, can anyone point me in the right direction? I did do the powerdfg -energy program and came up with this: Power Efficiency Diagnostics Report Scan Time 2014-05-08T19:21:48Z Scan Duration 60 seconds System Manufacturer Dell Inc. System Product Name XPS 8700 BIOS Date 08/23/2013 BIOS Version A04 OS Build 7601 Platform Role PlatformRoleDesktop Plugged In true Process Count 115 Thread Count 1631 Report GUID {097caf99-039b-44c3-b154-d797bfbfdfcc} Analysis Results Errors Power Policy:Sleep timeout is disabled (Plugged In) The computer is not configured to automatically sleep after a period of inactivity. System Availability Requests:System Required Request The device or driver has made a request to prevent the system from automatically entering sleep. Requesting Driver Instance HDAUDIO\FUNC_01&VEN_10EC&DEV_0899&SUBSYS_102805B7&REV_1000\4&220b1bbc&0&0001 Requesting Driver Device Realtek High Definition Audio CPU Utilization:Processor utilization is high The average processor utilization during the trace was high. The system will consume less power when the average processor utilization is very low. Review processor utilization for individual processes to determine which applications and services contribute the most to total processor utilization. Average Utilization (%) 9.48 Warnings Platform Timer Resolution:Platform Timer Resolution The default platform timer resolution is 15.6ms (15625000ns) and should be used whenever the system is idle. If the timer resolution is increased, processor power management technologies may not be effective. The timer resolution may be increased due to multimedia playback or graphical animations. Current Timer Resolution (100ns units) 10000 Maximum Timer Period (100ns units) 156001 Platform Timer Resolution:Outstanding Kernel Timer Request A kernel component or device driver has requested a timer resolution smaller than the platform maximum timer resolution. Requested Period 10000 Request Count 2 Platform Timer Resolution:Outstanding Timer Request A program or service has requested a timer resolution smaller than the platform maximum timer resolution. Requested Period 10000 Requesting Process ID 8672 Requesting Process Path \Device\HarddiskVolume3\Program Files (x86)\Mozilla Firefox\firefox.exe Platform Timer Resolution:Outstanding Timer Request A program or service has requested a timer resolution smaller than the platform maximum timer resolution. Requested Period 100000 Requesting Process ID 1212 Requesting Process Path \Device\HarddiskVolume3\Windows\System32\svchost.exe Power Policy:802.11 Radio Power Policy is Maximum Performance (Plugged In) The current power policy for 802.11-compatible wireless network adapters is not configured to use low-power modes. CPU Utilization:Individual process with significant processor utilization. This process is responsible for a significant portion of the total processor utilization recorded during the trace. Process Name audiodg.exe PID 1304 Average Utilization (%) 4.73 Module Average Module Utilization (%) \Device\HarddiskVolume3\Windows\System32\msvcrt.dll 1.88 \Device\HarddiskVolume3\Windows\System32\MaxxAudioAPO5064.dll 1.77 \Device\HarddiskVolume3\Windows\System32\AudioEng.dll 0.80 CPU Utilization:Individual process with significant processor utilization. This process is responsible for a significant portion of the total processor utilization recorded during the trace. Process Name thunderbird.exe PID 6036 Average Utilization (%) 0.35 Module Average Module Utilization (%) \Device\HarddiskVolume3\Program Files (x86)\Mozilla Thunderbird\xul.dll 0.16 \Device\HarddiskVolume3\Program Files (x86)\Mozilla Thunderbird\mozjs.dll 0.05 \SystemRoot\System32\win32k.sys 0.03 CPU Utilization:Individual process with significant processor utilization. This process is responsible for a significant portion of the total processor utilization recorded during the trace. Process Name dwm.exe PID 1340 Average Utilization (%) 0.25 Module Average Module Utilization (%) \Device\HarddiskVolume3\Windows\System32\dwmcore.dll 0.08 \Device\HarddiskVolume3\Windows\System32\nvwgf2umx.dll 0.05 \SystemRoot\system32\ntoskrnl.exe 0.03 CPU Utilization:Individual process with significant processor utilization. This process is responsible for a significant portion of the total processor utilization recorded during the trace.

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• Windows 7 disk errors after a few hours of runtime

  - by GFK

  I'm having trouble understanding what is going on with my work PC. Whenever I boot it, it runs fine for a while, then starts to randomly show disk errors. The displayed error often contains the message "not enough storage is available to process this command", although depending on the application that fails it can be different. This has happened for weeks now and is getting worse. This is what troubles me: It never seems to impact critical parts of the system (no BSOD, no freeze). Only some applications seem impacted, refusing to function correctly after a while: Outlook 2010 cannot download RSS feeds anymore, Firefox 6 or IE9 cannot download anything bigger than 3MB without failing, Windows Update fails, all msi installers fail, Visual Studio 2010 starts failing in weird manners... It only happens after a while using it (typically 3 hours, but it seems that installing a program or compiling several times makes it shorter) Rebooting solves it (temporarily). The system: The OS is Windows 7 Pro Spanish SP1, 32 bits The system is an HP Compaq 6000 Pro with 4 GB memory (only 3.4GB usable since the system is 32bit), one 500GB hard drive. Installed applications include: Visual Studio 2010, SQL Server 2008 R2, VMWare Workstation 7, Microsoft Security Essentials, Office 2010. Shutting down all related services and processes doesn't seem to change anything. The diagnostics I've run so far: Hard drive : 465GB, 165GB free Process Explorer : physical and virtual memory seem ok (pagefile is 5.3GB, physical memory usage 70%, system commit 39%) Windows Memory diagnostic tool: OK CHKDSK returned: 488282111 KB total disk space. 281668248 KB in 265779 files. 150188 KB in 62949 indexes. 0 KB in bad sectors. 571755 KB in use by the system. The log file has occupied 65536 kilobytes. 205891920 KB available on disk. For non-spanish speakers, that means all ok. SMART diagnostic tools (DiskCheckup) report all values normal. temperatures are in the normal range (HWinfo). The event viewer doesn't seem to contain any significant message. ran CCleaner 3, without any noticeable effect. I was thinking about some file number limit (between Visual Studio projects and other applications, there are around 300.000 files on the hard drive), but I couldn't find any. It's possible there is something related with the use of the temporary folders (it's the only explanation I have for why applications fail but Windows doesn't), but I cannot confirm that. Only thing I cannot find out is if chkdsk reporting 65MB for the log is normal. It seems since Vista it always reports this. Any other cleaning/diagnostic tool you might know of? Edit: I ran several other tools since I first published the question: Seagate SeaTools (the HD manufacturer's analysis tool): complete test run OK. Intel Rapid 10.1 (the HD controller manufacturer's troubleshooting tool): the HD's ok. Microsoft Desktop Heap Monitor: Desktop Heap Information Monitor Tool (Version 8.1.2925.0) Copyright (c) Microsoft Corporation. All rights reserved. Session ID: 1 Total Desktop: ( 46464 KB - 11 desktops) WinStation\Desktop Heap Size(KB) Used Rate(%) WinSta0\Winlogon (s1) 128 3.6 WinSta0\Disconnect (s1) 64 3.8 WinSta0\Default (s1) 20480 3.0 msswindowstation\mssrestricteddesk (s0) 1024 0.2 __X78B95_89_IW__A8D9S1_42_ID (s0) 1024 0.2 Service-0x0-3e5$\Default (s0) 1024 0.6 Service-0x0-3e4$\Default (s0) 1024 0.3 Service-0x0-3e7$\Default (s0) 1024 2.1 WinSta0\Winlogon (s0) 128 1.9 WinSta0\Disconnect (s0) 64 3.8 WinSta0\Default (s0) 20480 0.0 All ok, desktop heap usage < 5% Edit 2: I tried totally resetting my account by creating a new one, logging under this new one and delete the first one (local rights and files), then logging back with this deleted account (it is a domain account). No luck. Also, I found out often the error is "not enough storage is available to process this command". Searching on the internet, I found an old troubleshooting tip (setting a registry key to raise the IRP stack limit, whatever it is) which did not change anything.

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• Bye Bye Year of the Dragon, Hello BPM

  - by Ajay Khanna

  Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} As 2012 fades and we usher in a New Year, let’s look back at some of the hottest BPM trends and those we’ll be seeing more of in the coming months. BPM is as much about people as it is about technology. As people adopt new ways of engagement, new channels of communications and new devices to interact , the changes are reflected in BPM practices. As Social and Mobile have become an integral part of our personal and professional lives, we’ll see tighter integration of social and mobile with BPM, and more use cases emerging for smarter process management in 2013. And with products and services becoming less differentiated, organizations will strive to differentiate on Customer Experience. Concepts like Pace Layered Architecture and Dynamic Case Management will provide more flexibility and agility to IT groups and knowledge workers. Take a look at some of these capabilities we showcased (see video) at Oracle OpenWorld 2012. Some of these trends that will continue to gain momentum in 2013: Social networks and social media have provided a new way for businesses to engage with customers. A prospect is likely to reach out to their social network before making any purchase. Companies are increasingly engaging with customers in social networks to influence their purchasing decisions, as well as listening to customers via tools like sentiment analysis to see what customers think about a particular product or process. These insights are valuable as companies look to improve their processes. Inside organizations, workers are using social tools to engage with each other to design new products and processes. Social collaboration tools are being used to resolve issues where an employee needs consultation to reach a decision. Oracle BPM Suite includes social interaction as an integral part of its process design and work management to empower today’s business users. Ubiquitous smart mobile devices are trending as a tool of choice for many workers. Many companies are adopting the policy of “Bring Your Own Device,” and the device of choice is a tablet. Devices like smart phones and tablets not only provide mobility to workers and customers, but they also provide additional important information – the context. By integrating the mobile context (location, photos, and preferences) into your processes, organizations can make much more informed decisions, as well as offer more personalized service to customers. Using Oracle ADF Mobile, you can easily create user interfaces for mobile devices and also capture location data for process execution. Customer experience was at the forefront of trending topics in 2012. Organizations are trying to understand their customers better and offer them more personalized and differentiated services. Customer experience is paramount when companies design sales and support processes. Companies are looking to BPM to consistently and efficiently orchestrate customer facing processes across disparate systems, departments and channels of communication. Oracle BPM Suite provides just the right capabilities for organizations to design and deliver an excellent customer experience. Pace Layered Architecture strategy is gaining traction as a way to maximize agility and minimize disruption in organizations. It provides a framework to manage the evolution of your information system when different pieces of it are changing at different rates and need to be updated independent of one another. Oracle Fusion Middleware and Oracle BPM Suite are designed with this in mind. The database layer, integration layer, application layer, and process layer should not be required to change at the same time. Most of the business changes to policy or process can be done at the process layer without disrupting the whole infrastructure. By understanding the type of change needed at a particular level, organizations can become much more agile and efficient. Adaptive Case Management proposes more flexibility to manage processes or cases that do not follow a structured process flow. In such situations, the knowledge worker managing the case needs to evaluate what step should occur next because the sequence of steps can’t be predetermined. Another characteristic is that it requires much more collaboration than straight-through process. As simple processes become automated, and customers adopt more and more self-service, cases that reach the case workers are much more complex and need more investigation. Oracle BPM suite includes comprehensive adaptive case management capability to manage such unstructured and complex processes. Smart BPM or making your BPM intelligent has been the holy grail for BPM practitioners who imagined that one day BPM would become one with Business Intelligence, Business Activity Monitoring and Complex Event Processing, making it much more responsive and helpful in organizational decision making. In 2013, organizations will begin to deploy these intelligent BPM solutions. Oracle offers an integrated solution that brings together the powerful functionality of BI, BAM, event processing, and Real Time Decisions to help organizations create smart process based solutions. In order to help customers reach their BPM goals faster and remove risks associated with BPM initiatives, Oracle has introduced Oracle Process Accelerators, pre-built best practices applications built on Oracle BPM Suite that are fully production grade and ready to deploy. These are exiting times for BPM practitioners and there is so much to look forward to in 2013. We wish you a very happy and prosperous New Year 2013. Happy BPMing!

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• Oracle Data Mining a Star Schema: Telco Churn Case Study

  - by charlie.berger

  There is a complete and detailed Telco Churn case study "How to" Blog Series just posted by Ari Mozes, ODM Dev. Manager.  In it, Ari provides detailed guidance in how to leverage various strengths of Oracle Data Mining including the ability to: mine Star Schemas and join tables and views together to obtain a complete 360 degree view of a customer combine transactional data e.g. call record detail (CDR) data, etc. define complex data transformation, model build and model deploy analytical methodologies inside the Database  His blog is posted in a multi-part series.  Below are some opening excerpts for the first 3 blog entries.  This is an excellent resource for any novice to skilled data miner who wants to gain competitive advantage by mining their data inside the Oracle Database.  Many thanks Ari! Mining a Star Schema: Telco Churn Case Study (1 of 3) One of the strengths of Oracle Data Mining is the ability to mine star schemas with minimal effort.  Star schemas are commonly used in relational databases, and they often contain rich data with interesting patterns.  While dimension tables may contain interesting demographics, fact tables will often contain user behavior, such as phone usage or purchase patterns.  Both of these aspects - demographics and usage patterns - can provide insight into behavior.Churn is a critical problem in the telecommunications industry, and companies go to great lengths to reduce the churn of their customer base.  One case study1 describes a telecommunications scenario involving understanding, and identification of, churn, where the underlying data is present in a star schema.  That case study is a good example for demonstrating just how natural it is for Oracle Data Mining to analyze a star schema, so it will be used as the basis for this series of posts...... Mining a Star Schema: Telco Churn Case Study (2 of 3) This post will follow the transformation steps as described in the case study, but will use Oracle SQL as the means for preparing data.  Please see the previous post for background material, including links to the case study and to scripts that can be used to replicate the stages in these posts.1) Handling missing values for call data recordsThe CDR_T table records the number of phone minutes used by a customer per month and per call type (tariff).  For example, the table may contain one record corresponding to the number of peak (call type) minutes in January for a specific customer, and another record associated with international calls in March for the same customer.  This table is likely to be fairly dense (most type-month combinations for a given customer will be present) due to the coarse level of aggregation, but there may be some missing values.  Missing entries may occur for a number of reasons: the customer made no calls of a particular type in a particular month, the customer switched providers during the timeframe, or perhaps there is a data entry problem.  In the first situation, the correct interpretation of a missing entry would be to assume that the number of minutes for the type-month combination is zero.  In the other situations, it is not appropriate to assume zero, but rather derive some representative value to replace the missing entries.  The referenced case study takes the latter approach.  The data is segmented by customer and call type, and within a given customer-call type combination, an average number of minutes is computed and used as a replacement value.In SQL, we need to generate additional rows for the missing entries and populate those rows with appropriate values.  To generate the missing rows, Oracle's partition outer join feature is a perfect fit.  select cust_id, cdre.tariff, cdre.month, minsfrom cdr_t cdr partition by (cust_id) right outer join     (select distinct tariff, month from cdr_t) cdre     on (cdr.month = cdre.month and cdr.tariff = cdre.tariff);   ....... Mining a Star Schema: Telco Churn Case Study (3 of 3) Now that the "difficult" work is complete - preparing the data - we can move to building a predictive model to help identify and understand churn.The case study suggests that separate models be built for different customer segments (high, medium, low, and very low value customer groups).  To reduce the data to a single segment, a filter can be applied: create or replace view churn_data_high asselect * from churn_prep where value_band = 'HIGH'; It is simple to take a quick look at the predictive aspects of the data on a univariate basis.  While this does not capture the more complex multi-variate effects as would occur with the full-blown data mining algorithms, it can give a quick feel as to the predictive aspects of the data as well as validate the data preparation steps.  Oracle Data Mining includes a predictive analytics package which enables quick analysis. begin  dbms_predictive_analytics.explain(   'churn_data_high','churn_m6','expl_churn_tab'); end; /select * from expl_churn_tab where rank <= 5 order by rank; ATTRIBUTE_NAME       ATTRIBUTE_SUBNAME EXPLANATORY_VALUE RANK-------------------- ----------------- ----------------- ----------LOS_BAND                                      .069167052          1MINS_PER_TARIFF_MON  PEAK-5                   .034881648          2REV_PER_MON          REV-5                    .034527798          3DROPPED_CALLS                                 .028110322          4MINS_PER_TARIFF_MON  PEAK-4                   .024698149          5From the above results, it is clear that some predictors do contain information to help identify churn (explanatory value > 0).  The strongest uni-variate predictor of churn appears to be the customer's (binned) length of service.  The second strongest churn indicator appears to be the number of peak minutes used in the most recent month.  The subname column contains the interior piece of the DM_NESTED_NUMERICALS column described in the previous post.  By using the object relational approach, many related predictors are included within a single top-level column. .....   NOTE:  These are just EXCERPTS.  Click here to start reading the Oracle Data Mining a Star Schema: Telco Churn Case Study from the beginning.    

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• Building services with the .NET framework Cont’d

  - by Allan Rwakatungu

  In my previous blog I wrote an introductory post on services and how you can build services using the .NET frameworks Windows Communication Foundation (WCF) In this post I will show how to develop a real world application using WCF The problem During the last meeting we realized developers in Uganda are not so cool – they don’t use twitter so may not get the latest news and updates from the technology world. We also noticed they mostly use kabiriti phones (jokes). With their kabiriti phones they are unable to access the twitter web client or alternative twitter mobile clients like tweetdeck , twirl or tweetie. However, the kabiriti phones support SMS (Yeeeeeeei). So what we going to do to make these developers cool and keep them updated is by enabling them to receive tweets via SMS. We shall also enable them to develop their own applications that can extend this functionality Analysis Thanks to services and open API’s solving our problem is going to be easy.  1. To get tweets we can use the twitter service for FREE 2. To send SMS we shall use www.clickatell.com/ as they can send SMS to any country in the world. Besides we could not find any local service that offers API's for sending SMS :(. 3. To enable developers to integrate with our application so that they can extend it and build even cooler applications we use WCF. In addittion , because connectivity might be an issue we decided to use WCF because if has a inbuilt queing features. We also choose WCF because this is a post about .NET and WCF :). The Code Accessing the tweets To consume twitters REST API we shall use the WCF REST starter kit. Like it name indicates , the REST starter kit is a set of .NET framework classes that enable developers to create and access REST style services ( like the twitter service). Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.Http; using System.Net; using System.Xml.Linq;   namespace UG.Demo {     public class TwitterService     {         public IList<TwitterStatus> SomeMethodName()         {             //Connect to the twitter service (HttpClient is part of the REST startkit classes)             HttpClient cl = new HttpClient("http://api.twitter.com/1/statuses/friends_timeline.xml");             //Supply your basic authentication credentials             cl.TransportSettings.Credentials = new NetworkCredential("ourusername", "ourpassword");             //issue an http             HttpResponseMessage resp = cl.Get();             //ensure we got reponse 200             resp.EnsureStatusIsSuccessful();             //use XLinq to parse the REST XML             var statuses = from r in resp.Content.ReadAsXElement().Descendants("status")                            select new TwitterStatus                            {                                User = r.Element("user").Element("screen_name").Value,                                Status = r.Element("text").Value                            };             return statuses.ToList();         }     }     public class TwitterStatus     {         public string User { get; set; }         public string Status { get; set; }     } }  Sending SMS Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} public class SMSService     {         public void Send(string phone, string message)         {                         HttpClient cl1 = new HttpClient();              //the clickatell XML format for sending SMS             string xml = String.Format("<clickAPI><sendMsg><api_id>3239621</api_id><user>ourusername</user><password>ourpassword</password><to>{0}</to><text>{1}</text></sendMsg></clickAPI>",phone,message);             //Post form data             HttpUrlEncodedForm form = new HttpUrlEncodedForm();             form.Add("data", xml);             System.Net.ServicePointManager.Expect100Continue = false;             string uri = @"http://api.clickatell.com/xml/xml";             HttpResponseMessage resp = cl1.Post(uri, form.CreateHttpContent());             resp.EnsureStatusIsSuccessful();         }     }

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