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• The Java Specialist: An Interview with Java Champion Heinz Kabutz

  - by Janice J. Heiss

  Dr. Heinz Kabutz is well known for his Java Specialists’ Newsletter, initiated in November 2000, where he displays his acute grasp of the intricacies of the Java platform for an estimated 70,000 readers; for his work as a consultant; and for his workshops and trainings at his home on the Island of Crete where he has lived since 2006 -- where he is known to curl up on the beach with his laptop to hack away, in between dips in the Mediterranean. Kabutz was born of German parents and raised in Cape Town, South Africa, where he developed a love of programming in junior high school through his explorations on a ZX Spectrum computer. He received a B.S. from the University of Cape Town, and at 25, a Ph.D., both in computer science. He will be leading a two-hour hands-on lab session, HOL6500 – “Finding and Solving Java Deadlocks,” at this year’s JavaOne that will explore what causes deadlocks and how to solve them. Q: Tell us about your JavaOne plans.A: I am arriving on Sunday evening and have just one hands-on-lab to do on Monday morning. This is the first time that a non-Oracle team is doing a HOL at JavaOne under Oracle's stewardship and we are all a bit nervous about how it will turn out. Oracle has been immensely helpful in getting us set up. I have a great team helping me: Kirk Pepperdine, Dario Laverde, Benjamin Evans and Martijn Verburg from jClarity, Nathan Reynolds from Oracle, Henri Tremblay of OCTO Technology and Jeff Genender of Savoir Technologies. Monday will be hard work, but after that, I will hopefully get to network with fellow Java experts, attend interesting sessions and just enjoy San Francisco. Oh, and my kids have already given me a shopping list of things to get, like a GoPro Hero 2 dive housing for shooting those nice videos of Crete. (That's me at the beginning diving down.) Q: What sessions are you attending that we should know about?A: Sometimes the most unusual sessions are the best. I avoid the "big names". They often are spread too thin with all their sessions, which makes it difficult for them to deliver what I would consider deep content. I also avoid entertainers who might be good at presenting but who do not say that much.In 2010, I attended a session by Vladimir Yaroslavskiy where he talked about sorting. Although he struggled to speak English, what he had to say was spectacular. There was hardly anybody in the room, having not heard of Vladimir before. To me that was the highlight of 2010. Funnily enough, he was supposed to speak with Joshua Bloch, but if you remember, Google cancelled. If Bloch has been there, the room would have been packed to capacity.Q: Give us an update on the Java Specialists’ Newsletter.A: The Java Specialists' Newsletter continues being read by an elite audience around the world. The apostrophe in the name is significant.  It is a newsletter for Java specialists. When I started it twelve years ago, I was trying to find non-obvious things in Java to write about. Things that would be interesting to an advanced audience.As an April Fool's joke, I told my readers in Issue 44 that subscribing would remain free, but that they would have to pay US$5 to US$7 depending on their geographical location. I received quite a few angry emails from that one. I would have not earned that much from unsubscriptions. Most readers stay for a very long time.After Oracle bought Sun, the Java community held its breath for about two years whilst Oracle was figuring out what to do with Java. For a while, we were quite concerned that there was not much progress shown by Oracle. My newsletter still continued, but it was quite difficult finding new things to write about. We have probably about 70,000 readers, which is quite a small number for a Java publication. However, our readers are the top in the Java industry. So I don't mind having "only" 70000 readers, as long as they are the top 0.7%.Java concurrency is a very important topic that programmers think they should know about, but often neglect to fully understand. I continued writing about that and made some interesting discoveries. For example, in Issue 165, I showed how we can get thread starvation with the ReadWriteLock. This was a bug in Java 5, which was corrected in Java 6, but perhaps a bit too much. Whereas we could get starvation of writers in Java 5, in Java 6 we could now get starvation of readers. All of these interesting findings make their way into my courseware to help companies avoid these pitfalls.Another interesting discovery was how polymorphism works in the Server HotSpot compiler in Issue 157 and Issue 158. HotSpot can inline methods from interfaces that have only one implementation class in the JVM. When a new subclass is instantiated and called for the first time, the JVM will undo the previous optimization and re-optimize differently.Here is a little memory puzzle for your readers: public class JavaMemoryPuzzle {  private final int dataSize =      (int) (Runtime.getRuntime().maxMemory() * 0.6);  public void f() {    {      byte[] data = new byte[dataSize];    }    byte[] data2 = new byte[dataSize];  }  public static void main(String[] args) {    JavaMemoryPuzzle jmp = new JavaMemoryPuzzle();    jmp.f();  }}When you run this you will always get an OutOfMemoryError, even though the local variable data is no longer visible outside of the code block.So here comes the puzzle, that I'd like you to ponder a bit. If you very politely ask the VM to release memory, then you don't get an OutOfMemoryError: public class JavaMemoryPuzzlePolite {  private final int dataSize =      (int) (Runtime.getRuntime().maxMemory() * 0.6);  public void f() {    {      byte[] data = new byte[dataSize];    }    for(int i=0; i<10; i++) {      System.out.println("Please be so kind and release memory");    }    byte[] data2 = new byte[dataSize];  }  public static void main(String[] args) {    JavaMemoryPuzzlePolite jmp = new JavaMemoryPuzzlePolite();    jmp.f();    System.out.println("No OutOfMemoryError");  }}Why does this work? When I published this in my newsletter, I received over 400 emails from excited readers around the world, most of whom sent me the wrong explanation. After the 300th wrong answer, my replies became unfortunately a bit curt. Have a look at Issue 174 for a detailed explanation, but before you do, put on your thinking caps and try to figure it out yourself. Q: What do you think Java developers should know that they currently do not know?A: They should definitely get to know more about concurrency. It is a tough subject that most programmers try to avoid. Unfortunately we do come in contact with it. And when we do, we need to know how to protect ourselves and how to solve tricky system errors.Knowing your IDE is also useful. Most IDEs have a ton of shortcuts, which can make you a lot more productive in moving code around. Another thing that is useful is being able to read GC logs. Kirk Pepperdine has a great talk at JavaOne that I can recommend if you want to learn more. It's this: CON5405 – “Are Your Garbage Collection Logs Speaking to You?” Q: What are you looking forward to in Java 8?A: I'm quite excited about lambdas, though I must confess that I have not studied them in detail yet. Maurice Naftalin's Lambda FAQ is quite a good start to document what you can do with them. I'm looking forward to finding all the interesting bugs that we will now get due to lambdas obscuring what is really going on underneath, just like we had with generics.I am quite impressed with what the team at Oracle did with OpenJDK's performance. A lot of the benchmarks now run faster.Hopefully Java 8 will come with JSR 310, the Date and Time API. It still boggles my mind that such an important API has been left out in the cold for so long.What I am not looking forward to is losing perm space. Even though some systems run out of perm space, at least the problem is contained and they usually manage to work around it. In most cases, this is due to a memory leak in that region of memory. Once they bundle perm space with the old generation, I predict that memory leaks in perm space will be harder to find. More contracts for us, but also more pain for our customers. Originally published on blogs.oracle.com/javaone.

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• The Java Specialist: An Interview with Java Champion Heinz Kabutz

  - by Janice J. Heiss

  Dr. Heinz Kabutz is well known for his Java Specialists’ Newsletter, initiated in November 2000, where he displays his acute grasp of the intricacies of the Java platform for an estimated 70,000 readers; for his work as a consultant; and for his workshops and trainings at his home on the Island of Crete where he has lived since 2006 -- where he is known to curl up on the beach with his laptop to hack away, in between dips in the Mediterranean. Kabutz was born of German parents and raised in Cape Town, South Africa, where he developed a love of programming in junior high school through his explorations on a ZX Spectrum computer. He received a B.S. from the University of Cape Town, and at 25, a Ph.D., both in computer science. He will be leading a two-hour hands-on lab session, HOL6500 – “Finding and Solving Java Deadlocks,” at this year’s JavaOne that will explore what causes deadlocks and how to solve them. Q: Tell us about your JavaOne plans.A: I am arriving on Sunday evening and have just one hands-on-lab to do on Monday morning. This is the first time that a non-Oracle team is doing a HOL at JavaOne under Oracle's stewardship and we are all a bit nervous about how it will turn out. Oracle has been immensely helpful in getting us set up. I have a great team helping me: Kirk Pepperdine, Dario Laverde, Benjamin Evans and Martijn Verburg from jClarity, Nathan Reynolds from Oracle, Henri Tremblay of OCTO Technology and Jeff Genender of Savoir Technologies. Monday will be hard work, but after that, I will hopefully get to network with fellow Java experts, attend interesting sessions and just enjoy San Francisco. Oh, and my kids have already given me a shopping list of things to get, like a GoPro Hero 2 dive housing for shooting those nice videos of Crete. (That's me at the beginning diving down.) Q: What sessions are you attending that we should know about?A: Sometimes the most unusual sessions are the best. I avoid the "big names". They often are spread too thin with all their sessions, which makes it difficult for them to deliver what I would consider deep content. I also avoid entertainers who might be good at presenting but who do not say that much.In 2010, I attended a session by Vladimir Yaroslavskiy where he talked about sorting. Although he struggled to speak English, what he had to say was spectacular. There was hardly anybody in the room, having not heard of Vladimir before. To me that was the highlight of 2010. Funnily enough, he was supposed to speak with Joshua Bloch, but if you remember, Google cancelled. If Bloch has been there, the room would have been packed to capacity.Q: Give us an update on the Java Specialists’ Newsletter.A: The Java Specialists' Newsletter continues being read by an elite audience around the world. The apostrophe in the name is significant.  It is a newsletter for Java specialists. When I started it twelve years ago, I was trying to find non-obvious things in Java to write about. Things that would be interesting to an advanced audience.As an April Fool's joke, I told my readers in Issue 44 that subscribing would remain free, but that they would have to pay US$5 to US$7 depending on their geographical location. I received quite a few angry emails from that one. I would have not earned that much from unsubscriptions. Most readers stay for a very long time.After Oracle bought Sun, the Java community held its breath for about two years whilst Oracle was figuring out what to do with Java. For a while, we were quite concerned that there was not much progress shown by Oracle. My newsletter still continued, but it was quite difficult finding new things to write about. We have probably about 70,000 readers, which is quite a small number for a Java publication. However, our readers are the top in the Java industry. So I don't mind having "only" 70000 readers, as long as they are the top 0.7%.Java concurrency is a very important topic that programmers think they should know about, but often neglect to fully understand. I continued writing about that and made some interesting discoveries. For example, in Issue 165, I showed how we can get thread starvation with the ReadWriteLock. This was a bug in Java 5, which was corrected in Java 6, but perhaps a bit too much. Whereas we could get starvation of writers in Java 5, in Java 6 we could now get starvation of readers. All of these interesting findings make their way into my courseware to help companies avoid these pitfalls.Another interesting discovery was how polymorphism works in the Server HotSpot compiler in Issue 157 and Issue 158. HotSpot can inline methods from interfaces that have only one implementation class in the JVM. When a new subclass is instantiated and called for the first time, the JVM will undo the previous optimization and re-optimize differently.Here is a little memory puzzle for your readers: public class JavaMemoryPuzzle {  private final int dataSize =      (int) (Runtime.getRuntime().maxMemory() * 0.6);  public void f() {    {      byte[] data = new byte[dataSize];    }    byte[] data2 = new byte[dataSize];  }  public static void main(String[] args) {    JavaMemoryPuzzle jmp = new JavaMemoryPuzzle();    jmp.f();  }}When you run this you will always get an OutOfMemoryError, even though the local variable data is no longer visible outside of the code block.So here comes the puzzle, that I'd like you to ponder a bit. If you very politely ask the VM to release memory, then you don't get an OutOfMemoryError: public class JavaMemoryPuzzlePolite {  private final int dataSize =      (int) (Runtime.getRuntime().maxMemory() * 0.6);  public void f() {    {      byte[] data = new byte[dataSize];    }    for(int i=0; i<10; i++) {      System.out.println("Please be so kind and release memory");    }    byte[] data2 = new byte[dataSize];  }  public static void main(String[] args) {    JavaMemoryPuzzlePolite jmp = new JavaMemoryPuzzlePolite();    jmp.f();    System.out.println("No OutOfMemoryError");  }}Why does this work? When I published this in my newsletter, I received over 400 emails from excited readers around the world, most of whom sent me the wrong explanation. After the 300th wrong answer, my replies became unfortunately a bit curt. Have a look at Issue 174 for a detailed explanation, but before you do, put on your thinking caps and try to figure it out yourself. Q: What do you think Java developers should know that they currently do not know?A: They should definitely get to know more about concurrency. It is a tough subject that most programmers try to avoid. Unfortunately we do come in contact with it. And when we do, we need to know how to protect ourselves and how to solve tricky system errors.Knowing your IDE is also useful. Most IDEs have a ton of shortcuts, which can make you a lot more productive in moving code around. Another thing that is useful is being able to read GC logs. Kirk Pepperdine has a great talk at JavaOne that I can recommend if you want to learn more. It's this: CON5405 – “Are Your Garbage Collection Logs Speaking to You?” Q: What are you looking forward to in Java 8?A: I'm quite excited about lambdas, though I must confess that I have not studied them in detail yet. Maurice Naftalin's Lambda FAQ is quite a good start to document what you can do with them. I'm looking forward to finding all the interesting bugs that we will now get due to lambdas obscuring what is really going on underneath, just like we had with generics.I am quite impressed with what the team at Oracle did with OpenJDK's performance. A lot of the benchmarks now run faster.Hopefully Java 8 will come with JSR 310, the Date and Time API. It still boggles my mind that such an important API has been left out in the cold for so long.What I am not looking forward to is losing perm space. Even though some systems run out of perm space, at least the problem is contained and they usually manage to work around it. In most cases, this is due to a memory leak in that region of memory. Once they bundle perm space with the old generation, I predict that memory leaks in perm space will be harder to find. More contracts for us, but also more pain for our customers.

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• Gratuitous CRLF in Subject: line - why is it there, and is it legal?

  - by MadHatter

  I'm running into a problem with a NAGIOS system sending emails to a popular email-to-SMS service. The email-to-SMS service takes emails with text in the Subject: line, and sends them on to the mobile number encoded in the To: field. So far so good. Sadly, sendmail (and postfix before it) seem to be inserting a gratuitous CRLF into the (necessarily long) Subject: line, and that's causing my SMS messages to be truncated at the CRLF if and only if the Subject: line contains one or more colons past the gratuitous CRLF. I am confident that the messages are being created correctly, but just to be sure, here's me creating a completely noddy test message to myself, with a long Subject: line: echo "foo" | mail -s "1234567 101234567 201234567 301234567 401234567 501234567 601234567 701234567 801234567 90123456789" [email protected] Note there's no extra colon in this Subject: line; all I'm doing here is showing that an extra CRLF is inserted on the wire. Here's the result of sudo ngrep -x port 25: 44 61 74 65 3a 20 46 72    69 2c 20 33 31 20 4d 61    Date: Fri, 31 Ma 79 20 32 30 31 33 20 31    30 3a 34 33 3a 35 35 20    y 2013 10:43:55 2b 30 31 30 30 0d 0a 54    6f 3a 20 72 65 61 70 65    +0100..To: reape 72 40 74 65 61 70 61 72    74 79 2e 6e 65 74 0d 0a    [email protected].. 53 75 62 6a 65 63 74 3a    20 31 32 33 34 35 36 37    Subject: 1234567 20 31 30 31 32 33 34 35    36 37 20 32 30 31 32 33     101234567 20123 34 35 36 37 20 33 30 31    32 33 34 35 36 37 20 34    4567 301234567 4 30 31 32 33 34 35 36 37    20 35 30 31 32 33 34 35    01234567 5012345 36 37 0d 0a 20 36 30 31    32 33 34 35 36 37 20 37    67.. 601234567 7 30 31 32 33 34 35 36 37    20 38 30 31 32 33 34 35    01234567 8012345 36 37 20 39 30 31 32 33    34 35 36 37 38 39 0d 0a    67 90123456789.. 55 73 65 72 2d 41 67 65    6e 74 3a 20 48 65 69 72    User-Agent: Heir 6c 6f 6f 6d 20 6d 61 69    6c 78 20 31 32 2e 34 20    loom mailx 12.4 37 2f 32 39 2f 30 38 0d    0a 4d 49 4d 45 2d 56 65    7/29/08..MIME-Ve 72 73 69 6f 6e 3a 20 31    2e 30 0d 0a 43 6f 6e 74    rsion: 1.0..Cont 65 6e 74 2d 54 79 70 65    3a 20 74 65 78 74 2f 70    ent-Type: text/p 6c 61 69 6e 3b 20 63 68    61 72 73 65 74 3d 75 73    lain; charset=us About half way down (marked in bold+italic), between the 501234567 and the 601234567 in the original Subject: header, you can see a CRLF being inserted (0x0d 0x0a, on the left-hand side hex dump, .. on the right-hand side plain text). The receiving MTA seems happy to post-process this, and when I look at the on-disc stored mail at the receiving end, I see only a LF (0x0a) in the Subject: line, and the line is parsed correctly and in its entirety by, eg, alpine. Nevertheless, the CRLF is there on the wire, and between me and the (excellent) email-to-SMS support people, we've established that these are the cause of the problem. So my question is: is it lawful for an MTA to insert a gratuitous CRLF on the wire? If it is, and I can prove it, then it's the email-to-SMS house's problem, because they are being intolerant. If it isn't, or it is but I can't prove it, then it becomes my problem, so an answer with references would be most useful. Edit: I can now come clean that the email-to-SMS service in question is kapow. Once this problem was explained to them, they got it, worked with me to develop and test a fix, and have deployed the fix. My long subject lines with colons in now get relayed correctly into SMSes. I don't normally trumpet individual companies, especially not on SF, but I thought it worthy of note that kapow Did The Right Thing. (Disclaimer: I have no connection with kapow except as a paying customer who's happy about the way they dealt with his problem.)

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• My sound stopped working today, how can I fix it?

  - by Oli

  This seems to be a problem with pulseaudio. I was logged in over VNC on my phone and started playing a video this caused X to crash (as sometimes happens). I restarted and suddenly the sound doesn't work. I have a Intel HDA/Realtek ALC889 00:1b.0 Audio device: Intel Corporation 82801JI (ICH10 Family) HD Audio Controller alsamixer is detecting this just fine. PulseAudio doesn't detect this alsa device so is using auto_null as the default sink (logs below). When I properly kill PulseAudio (tell it not to auto-start) direct ALSA communication with the sound card works just fine. speaker-test, for example, works. So the hardware and ALSA layers are fine IMO. In the logs, it seems that the card might be "busy" but I really don't know how or why it would be now (and never before). Is there an ALSA lock file somewhere that it still there because of my crash? I just ran sudo fuser /dev/snd/* and saw this: oli@bert:~$ sudo fuser /dev/snd/* /dev/snd/controlC0: 1884 /dev/snd/pcmC0D0c: 1884m /dev/snd/timer: 1884 A look at the process list (ps aux | grep 1884) tells me process 1884 is arecord -c 1 -f S16_LE -r 8000 -t raw. No idea what this is or why it's running. When I try and kill arecord (as root), it just respawns and rebinds on the hardware. I'm in a very annoying situation where I don't know what is going on and don't know how to find out. I'm open to all suggestions to get this working again. Fire away. And here's what I get when I stop PA auto-loading, kill it and then start it with -vvvv. oli@bert:~$ pulseaudio -vvvvv I: main.c: setrlimit(RLIMIT_NICE, (31, 31)) failed: Operation not permitted I: main.c: setrlimit(RLIMIT_RTPRIO, (9, 9)) failed: Operation not permitted D: core-rtclock.c: Timer slack is set to 50 us. D: core-util.c: RealtimeKit worked. I: core-util.c: Successfully gained nice level -11. I: main.c: This is PulseAudio 0.9.21-63-gd3efa-dirty D: main.c: Compilation host: x86_64-pc-linux-gnu D: main.c: Compilation CFLAGS: -g -O2 -g -Wall -O3 -Wall -W -Wextra -pipe -Wno-long-long -Winline -Wvla -Wno-overlength-strings -Wunsafe-loop-optimizations -Wundef -Wformat=2 -Wlogical-op -Wsign-compare -Wformat-security -Wmissing-include-dirs -Wformat-nonliteral -Wold-style-definition -Wpointer-arith -Winit-self -Wdeclaration-after-statement -Wfloat-equal -Wmissing-prototypes -Wstrict-prototypes -Wredundant-decls -Wmissing-declarations -Wmissing-noreturn -Wshadow -Wendif-labels -Wcast-align -Wstrict-aliasing=2 -Wwrite-strings -Wno-unused-parameter -ffast-math -Wp,-D_FORTIFY_SOURCE=2 -fno-common -fdiagnostics-show-option D: main.c: Running on host: Linux x86_64 2.6.38-rc3 #1 SMP Tue Feb 1 10:53:04 GMT 2011 D: main.c: Found 8 CPUs. I: main.c: Page size is 4096 bytes D: main.c: Compiled with Valgrind support: no D: main.c: Running in valgrind mode: no D: main.c: Running in VM: no D: main.c: Optimised build: yes D: main.c: All asserts enabled. I: main.c: Machine ID is 8310740c4729ef474fe5ecec4bbf5a6b. I: main.c: Session ID is 8310740c4729ef474fe5ecec4bbf5a6b-1297338553.571075-1050119523. I: main.c: Using runtime directory /home/oli/.pulse/8310740c4729ef474fe5ecec4bbf5a6b-runtime. I: main.c: Using state directory /home/oli/.pulse. I: main.c: Using modules directory /usr/lib/pulse-0.9.21/modules. I: main.c: Running in system mode: no I: main.c: Fresh high-resolution timers available! Enjoy ol' chap! I: cpu-x86.c: CPU flags: CMOV MMX SSE SSE2 SSE3 SSSE3 SSE4_1 SSE4_2 I: svolume_mmx.c: Initialising MMX optimized functions. I: remap_mmx.c: Initialising MMX optimized remappers. I: svolume_sse.c: Initialising SSE2 optimized functions. I: remap_sse.c: Initialising SSE2 optimized remappers. I: sconv_sse.c: Initialising SSE2 optimized conversions. D: memblock.c: Using shared memory pool with 1024 slots of size 64.0 KiB each, total size is 64.0 MiB, maximum usable slot size is 65472 D: database-tdb.c: Opened TDB database '/home/oli/.pulse/8310740c4729ef474fe5ecec4bbf5a6b-device-volumes.tdb' I: module-device-restore.c: Sucessfully opened database file '/home/oli/.pulse/8310740c4729ef474fe5ecec4bbf5a6b-device-volumes'. I: module.c: Loaded "module-device-restore" (index: #0; argument: ""). D: database-tdb.c: Opened TDB database '/home/oli/.pulse/8310740c4729ef474fe5ecec4bbf5a6b-stream-volumes.tdb' I: module-stream-restore.c: Sucessfully opened database file '/home/oli/.pulse/8310740c4729ef474fe5ecec4bbf5a6b-stream-volumes'. I: module.c: Loaded "module-stream-restore" (index: #1; argument: ""). D: database-tdb.c: Opened TDB database '/home/oli/.pulse/8310740c4729ef474fe5ecec4bbf5a6b-card-database.tdb' I: module-card-restore.c: Sucessfully opened database file '/home/oli/.pulse/8310740c4729ef474fe5ecec4bbf5a6b-card-database'. I: module.c: Loaded "module-card-restore" (index: #2; argument: ""). I: module.c: Loaded "module-augment-properties" (index: #3; argument: ""). D: cli-command.c: Checking for existance of '/usr/lib/pulse-0.9.21/modules/module-udev-detect.so': success D: module-udev-detect.c: /dev/snd/controlC0 is accessible: yes D: module-udev-detect.c: /devices/pci0000:00/0000:00:1b.0/sound/card0 is busy: yes I: module-udev-detect.c: Found 1 cards. I: module.c: Loaded "module-udev-detect" (index: #4; argument: ""). D: cli-command.c: Checking for existance of '/usr/lib/pulse-0.9.21/modules/module-bluetooth-discover.so': success D: dbus-util.c: Successfully connected to D-Bus system bus ba7c9a1f90b3d49d930bca2100000015 as :1.62 D: bluetooth-util.c: dbus: interface=org.freedesktop.DBus, path=/org/freedesktop/DBus, member=NameAcquired D: bluetooth-util.c: Bluetooth daemon is apparently not available. I: module.c: Loaded "module-bluetooth-discover" (index: #5; argument: ""). D: cli-command.c: Checking for existance of '/usr/lib/pulse-0.9.21/modules/module-esound-protocol-unix.so': success I: module.c: Loaded "module-esound-protocol-unix" (index: #6; argument: ""). I: module.c: Loaded "module-native-protocol-unix" (index: #7; argument: ""). D: cli-command.c: Checking for existance of '/usr/lib/pulse-0.9.21/modules/module-gconf.so': success I: module.c: Loaded "module-gconf" (index: #8; argument: ""). I: module-default-device-restore.c: Saved default sink 'auto_null' not existant, not restoring default sink setting. I: module-default-device-restore.c: Saved default source 'auto_null.monitor' not existant, not restoring default source setting. I: module.c: Loaded "module-default-device-restore" (index: #9; argument: ""). I: module.c: Loaded "module-rescue-streams" (index: #10; argument: ""). D: module-always-sink.c: Autoloading null-sink as no other sinks detected. I: sink.c: Created sink 0 "auto_null" with sample spec s16le 6ch 44100Hz and channel map front-left,front-left-of-center,front-center,front-right,front-right-of-center,rear-center I: sink.c: device.description = "Dummy Output" I: sink.c: device.class = "abstract" I: sink.c: device.icon_name = "audio-card" D: core-subscribe.c: Dropped redundant event due to change event. I: source.c: Created source 0 "auto_null.monitor" with sample spec s16le 6ch 44100Hz and channel map front-left,front-left-of-center,front-center,front-right,front-right-of-center,rear-center I: source.c: device.description = "Monitor of Dummy Output" I: source.c: device.class = "monitor" I: source.c: device.icon_name = "audio-input-microphone" D: module-null-sink.c: Thread starting up I: module.c: Loaded "module-null-sink" (index: #11; argument: "sink_name=auto_null sink_properties='device.description="Dummy Output"'"). I: module.c: Loaded "module-always-sink" (index: #12; argument: ""). I: module.c: Loaded "module-intended-roles" (index: #13; argument: ""). D: module-suspend-on-idle.c: Sink auto_null becomes idle, timeout in 5 seconds. I: module.c: Loaded "module-suspend-on-idle" (index: #14; argument: ""). I: client.c: Created 0 "ConsoleKit Session /org/freedesktop/ConsoleKit/Session1" D: module-console-kit.c: Added new session /org/freedesktop/ConsoleKit/Session1 I: module.c: Loaded "module-console-kit" (index: #15; argument: ""). I: module.c: Loaded "module-position-event-sounds" (index: #16; argument: ""). D: dbus-util.c: Successfully connected to D-Bus session bus efbffc6788fad56cfd64d40c00000018 as :1.182 D: main.c: Got org.pulseaudio.Server! I: main.c: Daemon startup complete. I: client.c: Created 1 "Native client (UNIX socket client)" I: client.c: Created 2 "Native client (UNIX socket client)" D: protocol-native.c: Protocol version: remote 16, local 16 I: protocol-native.c: Got credentials: uid=1000 gid=1000 success=1 D: protocol-native.c: SHM possible: yes D: protocol-native.c: Negotiated SHM: yes D: protocol-native.c: Protocol version: remote 16, local 16 I: protocol-native.c: Got credentials: uid=1000 gid=1000 success=1 D: protocol-native.c: SHM possible: yes D: protocol-native.c: Negotiated SHM: yes D: module-augment-properties.c: Looking for .desktop file for gnome-volume-control-applet D: module-augment-properties.c: Looking for .desktop file for gnome-settings-daemon D: core-subscribe.c: Dropped redundant event due to change event. I: module-suspend-on-idle.c: Sink auto_null idle for too long, suspending ... D: sink.c: Suspend cause of sink auto_null is 0x0004, suspending Note the one section that seems to find the hardware but says it's busy (no idea if this is relevant). D: cli-command.c: Checking for existance of '/usr/lib/pulse-0.9.21/modules/module-udev-detect.so': success D: module-udev-detect.c: /dev/snd/controlC0 is accessible: yes D: module-udev-detect.c: /devices/pci0000:00/0000:00:1b.0/sound/card0 is busy: yes I: module-udev-detect.c: Found 1 cards.

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• How-to delete a tree node using the context menu

  - by frank.nimphius

  Hierarchical trees in Oracle ADF make use of View Accessors, which means that only the top level node needs to be exposed as a View Object instance on the ADF Business Components Data Model. This also means that only the top level node has a representation in the PageDef file as a tree binding and iterator binding reference. Detail nodes are accessed through tree rule definitions that use the accessor mentioned above (or nested collections in the case of POJO or EJB business services). The tree component is configured for single node selection, which however can be declaratively changed for users to press the ctrl key and selecting multiple nodes. In the following, I explain how to create a context menu on the tree for users to delete the selected tree nodes. For this, the context menu item will access a managed bean, which then determines the selected node(s), the internal ADF node bindings and the rows they represent. As mentioned, the ADF Business Components Data Model only needs to expose the top level node data sources, which in this example is an instance of the Locations View Object. For the tree to work, you need to have associations defined between entities, which usually is done for you by Oracle JDeveloper if the database tables have foreign keys defined Note: As a general hint of best practices and to simplify your life: Make sure your database schema is well defined and designed before starting your development project. Don't treat the database as something organic that grows and changes with the requirements as you proceed in your project. Business service refactoring in response to database changes is possible, but should be treated as an exception, not the rule. Good database design is a necessity – even for application developers – and nothing evil. To create the tree component, expand the Data Controls panel and drag the View Object collection to the view. From the context menu, select the tree component entry and continue with defining the tree rules that make up the hierarchical structure. As you see, when pressing the green plus icon  in the Edit Tree Binding  dialog, the data structure, Locations -  Departments – Employees in my sample, shows without you having created a View Object instance for each of the nodes in the ADF Business Components Data Model. After you configured the tree structure in the Edit Tree Binding dialog, you press OK and the tree is created. Select the tree in the page editor and open the Structure Window (ctrl+shift+S). In the Structure window, expand the tree node to access the conextMenu facet. Use the right mouse button to insert a Popup  into the facet. Repeat the same steps to insert a Menu and a Menu Item into the Popup you created. The Menu item text should be changed to something meaningful like "Delete". Note that the custom menu item later is added to the context menu together with the default context menu options like expand and expand all. To define the action that is executed when the menu item is clicked on, you select the Action Listener property in the Property Inspector and click the arrow icon followed by the Edit menu option. Create or select a managed bean and define a method name for the action handler. Next, select the tree component and browse to its binding property in the Property Inspector. Again, use the arrow icon | Edit option to create a component binding in the same managed bean that has the action listener defined. The tree handle is used in the action listener code, which is shown below: public void onTreeNodeDelete(ActionEvent actionEvent) {   //access the tree from the JSF component reference created   //using the af:tree "binding" property. The "binding" property   //creates a pair of set/get methods to access the RichTree instance   RichTree tree = this.getTreeHandler();   //get the list of selected row keys   RowKeySet rks = tree.getSelectedRowKeys();   //access the iterator to loop over selected nodes   Iterator rksIterator = rks.iterator();          //The CollectionModel represents the tree model and is   //accessed from the tree "value" property   CollectionModel model = (CollectionModel) tree.getValue();   //The CollectionModel is a wrapper for the ADF tree binding   //class, which is JUCtrlHierBinding   JUCtrlHierBinding treeBinding =                  (JUCtrlHierBinding) model.getWrappedData();          //loop over the selected nodes and delete the rows they   //represent   while(rksIterator.hasNext()){     List nodeKey = (List) rksIterator.next();     //find the ADF node binding using the node key     JUCtrlHierNodeBinding node =                       treeBinding.findNodeByKeyPath(nodeKey);     //delete the row.     Row rw = node.getRow();       rw.remove();   }          //only refresh the tree if tree nodes have been selected   if(rks.size() > 0){     AdfFacesContext adfFacesContext =                          AdfFacesContext.getCurrentInstance();     adfFacesContext.addPartialTarget(tree);   } } Note: To enable multi node selection for a tree, select the tree and change the row selection setting from "single" to "multiple". Note: a fully pictured version of this post will become available at the end of the month in a PDF summary on ADF Code Corner : http://www.oracle.com/technetwork/developer-tools/adf/learnmore/index-101235.html 

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• Day 3 - XNA: Hacking around with images

  - by dapostolov

  Yay! Today I'm going to get into some code! My mind has been on this all day! I find it amusing how I practice, daily, to be "in the moment" or "present" and the excitement and anticipation of this project seems to snatch it away from me frequently. WELL!!! (Shakes Excitedly) Let's do this =)! Let's code! For these next few days it is my intention to better understand image rendering using XNA; after said prototypes are complete I should (fingers crossed) be able to dive into my game code using the design document I hammered out the other night. On a personal note, I think the toughest thing right now is finding the time to do this project. Each night, after my little ones go to bed I can only really afford a couple hours of work on this project. However, I hope to utilise this time as best as I can because this is the first time in a while I've found a project that I've been passionate about. A friend recently asked me if I intend to go 3D or extend the game design. Yes. For now I'm keeping it simple. Lastly, just as a note, as I was doing some further research into image rendering this morning I came across some other XNA content and lessons learned. I believe this content could have probably been posted in the first couple of posts, however, I will share the new content as I learn it at the end of each day. Maybe I'll take some time later to fix the posts but for now Installation and Deployment - Lessons Learned I had installed the XNA studio  (Day 1) and the site instructions were pretty easy to follow. However, I had a small difficulty with my development environment. You see, I run a virtual desktop development environment. Even though I was able to code and compile all the tutorials the game failed to run...because I lacked a 3D capable card; it was not detected on the virtual box... First Lesson: The XNA runtime needs to "see" the 3D card! No sweat, Il copied the files over to my parent box and executed the program. ERROR. Hmm... Second Lesson (which I should have probably known but I let the excitement get the better of me): you need the XNA runtime on the client PC to run the game, oh, and don't forget the .Net Runtime! Sprite, it ain't just a Soft Drink... With these prototypes I intend to understand and perform the following tasks. learn game development terminology how to place and position (rotate) a static image on the screen how to layer static images on the screen understand image scaling can we reuse images? understand how framerate is handled in XNA how to display text , basic shapes, and colors on the screen how to interact with an image (collision of user input?) how to animate an image and understand basic animation techniques how to detect colliding images or screen edges how to manipulate the image, lets say colors, stretching how to focus on a segment of an image...like only displaying a frame on a film reel what's the best way to manage images (compression, storage, location, prevent artwork theft, etc.) Well, let's start with this "prototype" task list for now...Today, let's get an image on the screen and maybe I can mark a few of the tasks as completed... C# Prototype1 New Visual Studio Project Select the XNA Game Studio 3.1 Project Type Select the Windows Game 3.1 Template Type Prototype1 in the Name textbox provided Press OK. At this point code has auto-magically been created. Feel free to press the F5 key to run your first XNA program. You should have a blue screen infront of you. Without getting into the nitty gritty right, the code that was generated basically creates some basic code to clear the window content with the lovely CornFlowerBlue color. Something to notice, when you move your mouse into the window...nothing. ooooo spoooky. Let's put an image on that screen! Step A - Get an Image into the solution Under "Content" in your Solution Explorer, right click and add a new folder and name it "Sprites". Copy a small image in there; I copied a "Royalty Free" wizard hat from a quick google search and named it wizards_hat.jpg (rightfully so!) Step B - Add the sprite and position fields Now, open/edit  Game1.cs Locate the following line:  SpriteBatch spriteBatch; Under this line type the following:         SpriteBatch spriteBatch; // the line you are looking for...         Texture2D sprite;         Vector2 position; Step C - Load the image asset Locate the "Load Content" Method and duplicate the following:             protected override void LoadContent()         {             spriteBatch = new SpriteBatch(GraphicsDevice);             // your image name goes here...             sprite = Content.Load<Texture2D>("Sprites\\wizards_hat");             position = new Vector2(200, 100);             base.LoadContent();         } Step D - Draw the image Locate the "Draw" Method and duplicate the following:        protected override void Draw(GameTime gameTime)         {             GraphicsDevice.Clear(Color.CornflowerBlue);             spriteBatch.Begin(SpriteBlendMode.AlphaBlend);             spriteBatch.Draw(sprite, position, Color.White);             spriteBatch.End();             base.Draw(gameTime);         }  Step E - Compile and Run Engage! (F5) - Debug! Your image should now display on a cornflowerblue window about 200 pixels from the left and 100 pixels from the top. Awesome! =) Pretty cool how we only coded a few lines to display an image, but believe me, there is plenty going on behind the scenes. However, for now, I'm going to call it a night here. Blogging all this progress certainly takes time... However, tomorrow night I'm going to detail what we just did, plus start checking off points on that list! I'm wondering right now if I should add pictures / code to this post...let me know if you want them =) Best Regards, D.

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• The Stub Proto: Not Just For Stub Objects Anymore

  - by user9154181

  One of the great pleasures of programming is to invent something for a narrow purpose, and then to realize that it is a general solution to a broader problem. In hindsight, these things seem perfectly natural and obvious. The stub proto area used to build the core Solaris consolidation has turned out to be one of those things. As discussed in an earlier article, the stub proto area was invented as part of the effort to use stub objects to build the core ON consolidation. Its purpose was merely as a place to hold stub objects. However, we keep finding other uses for it. It turns out that the stub proto should be more properly thought of as an auxiliary place to put things that we would like to put into the proto to help us build the product, but which we do not wish to package or deliver to the end user. Stub objects are one example, but private lint libraries, header files, archives, and relocatable objects, are all examples of things that might profitably go into the stub proto. Without a stub proto, these items were handled in a variety of ad hoc ways: If one part of the workspace needed private header files, libraries, or other such items, it might modify its Makefile to reach up and over to the place in the workspace where those things live and use them from there. There are several problems with this: Each component invents its own approach, meaning that programmers maintaining the system have to invest extra effort to understand what things mean. In the past, this has created makefile ghettos in which only the person who wrote the makefiles feels confident to modify them, while everyone else ignores them. This causes many difficulties and benefits no one. These interdependencies are not obvious to the make, utility, and can lead to races. They are not obvious to the human reader, who may therefore not realize that they exist, and break them. Our policy in ON is not to deliver files into the proto unless those files are intended to be packaged and delivered to the end user. However, sometimes non-shipping files were copied into the proto anyway, causing a different set of problems: It requires a long list of exceptions to silence our normal unused proto item error checking. In the past, we have accidentally shipped files that we did not intend to deliver to the end user. Mixing cruft with valuable items makes it hard to discern which is which. The stub proto area offers a convenient and robust solution. Files needed to build the workspace that are not delivered to the end user can instead be installed into the stub proto. No special exceptions or custom make rules are needed, and the intent is always clear. We are already accessing some private lint libraries and compilation symlinks in this manner. Ultimately, I'd like to see all of the files in the proto that have a packaging exception delivered to the stub proto instead, and for the elimination of all existing special case makefile rules. This would include shared objects, header files, and lint libraries. I don't expect this to happen overnight — it will be a long term case by case project, but the overall trend is clear. The Stub Proto, -z assert_deflib, And The End Of Accidental System Object Linking We recently used the stub proto to solve an annoying build issue that goes back to the earliest days of Solaris: How to ensure that we're linking to the OS bits we're building instead of to those from the running system. The Solaris product is made up of objects and files from a number of different consolidations, each of which is built separately from the others from an independent code base called a gate. The core Solaris OS consolidation is ON, which stands for "Operating System and Networking". You will frequently also see ON called the OSnet. There are consolidations for X11 graphics, the desktop environment, open source utilities, compilers and development tools, and many others. The collection of consolidations that make up Solaris is known as the "Wad Of Stuff", usually referred to simply as the WOS. None of these consolidations is self contained. Even the core ON consolidation has some dependencies on libraries that come from other consolidations. The build server used to build the OSnet must be running a relatively recent version of Solaris, which means that its objects will be very similar to the new ones being built. However, it is necessarily true that the build system objects will always be a little behind, and that incompatible differences may exist. The objects built by the OSnet link to other objects. Some of these dependencies come from the OSnet, while others come from other consolidations. The objects from other consolidations are provided by the standard library directories on the build system (/lib, /usr/lib). The objects from the OSnet itself are supposed to come from the proto areas in the workspace, and not from the build server. In order to achieve this, we make use of the -L command line option to the link-editor. The link-editor finds dependencies by looking in the directories specified by the caller using the -L command line option. If the desired dependency is not found in one of these locations, ld will then fall back to looking at the default locations (/lib, /usr/lib). In order to use OSnet objects from the workspace instead of the system, while still accessing non-OSnet objects from the system, our Makefiles set -L link-editor options that point at the workspace proto areas. In general, this works well and dependencies are found in the right places. However, there have always been failures: Building objects in the wrong order might mean that an OSnet dependency hasn't been built before an object that needs it. If so, the dependency will not be seen in the proto, and the link-editor will silently fall back to the one on the build server. Errors in the makefiles can wipe out the -L options that our top level makefiles establish to cause ld to look at the workspace proto first. In this case, all objects will be found on the build server. These failures were rarely if ever caught. As I mentioned earlier, the objects on the build server are generally quite close to the objects built in the workspace. If they offer compatible linking interfaces, then the objects that link to them will behave properly, and no issue will ever be seen. However, if they do not offer compatible linking interfaces, the failure modes can be puzzling and hard to pin down. Either way, there won't be a compile-time warning or error. The advent of the stub proto eliminated the first type of failure. With stub objects, there is no dependency ordering, and the necessary stub object dependency will always be in place for any OSnet object that needs it. However, makefile errors do still occur, and so, the second form of error was still possible. While working on the stub object project, we realized that the stub proto was also the key to solving the second form of failure caused by makefile errors: Due to the way we set the -L options to point at our workspace proto areas, any valid object from the OSnet should be found via a path specified by -L, and not from the default locations (/lib, /usr/lib). Any OSnet object found via the default locations means that we've linked to the build server, which is an error we'd like to catch. Non-OSnet objects don't exist in the proto areas, and so are found via the default paths. However, if we were to create a symlink in the stub proto pointing at each non-OSnet dependency that we require, then the non-OSnet objects would also be found via the paths specified by -L, and not from the link-editor defaults. Given the above, we should not find any dependency objects from the link-editor defaults. Any dependency found via the link-editor defaults means that we have a Makefile error, and that we are linking to the build server inappropriately. All we need to make use of this fact is a linker option to produce a warning when it happens. Although warnings are nice, we in the OSnet have a zero tolerance policy for build noise. The -z fatal-warnings option that was recently introduced with -z guidance can be used to turn the warnings into fatal build errors, forcing the programmer to fix them. This was too easy to resist. I integrated 7021198 ld option to warn when link accesses a library via default path PSARC/2011/068 ld -z assert-deflib option into snv_161 (February 2011), shortly after the stub proto was introduced into ON. This putback introduced the -z assert-deflib option to the link-editor: -z assert-deflib=[libname] Enables warning messages for libraries specified with the -l command line option that are found by examining the default search paths provided by the link-editor. If a libname value is provided, the default library warning feature is enabled, and the specified library is added to a list of libraries for which no warnings will be issued. Multiple -z assert-deflib options can be specified in order to specify multiple libraries for which warnings should not be issued. The libname value should be the name of the library file, as found by the link-editor, without any path components. For example, the following enables default library warnings, and excludes the standard C library. ld ... -z assert-deflib=libc.so ... -z assert-deflib is a specialized option, primarily of interest in build environments where multiple objects with the same name exist and tight control over the library used is required. If is not intended for general use. Note that the definition of -z assert-deflib allows for exceptions to be specified as arguments to the option. In general, the idea of using a symlink from the stub proto is superior because it does not clutter up the link command with a long list of objects. When building the OSnet, we usually use the plain from of -z deflib, and make symlinks for the non-OSnet dependencies. The exception to this are dependencies supplied by the compiler itself, which are usually found at whatever arbitrary location the compiler happens to be installed at. To handle these special cases, the command line version works better. Following the integration of the link-editor change, I made use of -z assert-deflib in OSnet builds with 7021896 Prevent OSnet from accidentally linking to build system which integrated into snv_162 (March 2011). Turning on -z assert-deflib exposed between 10 and 20 existing errors in our Makefiles, which were all fixed in the same putback. The errors we found in our Makefiles underscore how difficult they can be prevent without an automatic system in place to catch them. Conclusions The stub proto is proving to be a generally useful construct for ON builds that goes beyond serving as a place to hold stub objects. Although invented to hold stub objects, it has already allowed us to simplify a number of previously difficult situations in our makefiles and builds. I expect that we'll find uses for it beyond those described here as we go forward.

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• Goodbye my beloved Nexus One, hello Windows Phone 7

  - by George Clingerman

  Last night my wife’s Nexus One finally bit the dust. You may not know but I’ve been nursing her Nexus One one along for quite a while after her screen shattered. I was able to replace it on my own (go me!) but little quirks have been popping up and the phone was quickly deteriorating. Lately it’s been the power button. Wifey would often have to press the power button several times to get her phone to turn on and last night it just wouldn’t wake up again. I took it apart and tried my best to see if I could somehow make it live once again but no luck this time. It was finally ready to retire. We looked at first for a replacement phone for her but she wasn’t really seeing anything she liked. So I decided to make the ultimate sacrifice and offer up my much loved Nexus One and I would then get a new Windows Phone 7 device. I love T-Mobile for my service so my choices were immediately limited to basically just a single phone. The HTC HD7. I read reviews and they were all over the board from people loving to people hating the phone but I decided, hey, why not, let’s take this plunge. And I did. I’ve only had the phone for about two days now so below is my list of first reaction pros/cons. These are basically things I’ve missed or things I’ve noticed that I really like about my new Windows Phone. Cons: * No Google Talk – I used this a LOT on my Nexus. I’ve found an application called “Flory” but it’s just an ok substitute, not the same as the full featured GTalk I had on my Nexus. * Seesmic is limited– I loved the way Seesmic worked on my Nexus. It was my mobile twitter client of choice. Everything about it worked really well. On Windows Phone 7 it’s just ok. I don’t get notification of new tweets, it’s several clicks to even see a new tweet. It’s definitely got some more development before it has the same features as it did on my Nexus. * Buttons don’t give great feedback – I’d read this on the reviews about the HTC HD7 and I’m finding it true myself. Pressing the buttons on the side of the phone and the power button on the top is finicky and I have to be looking at my phone to make sure I actually got them to press. * Web browsing is slow – I’m not sure what’s up with this, I’m connected to my wireless network at my house but it’s noticeably slower on my WP7 device than my Nexus. I even switched back to verify and it’s definitely true. Retrieving tweets, hitting up the XNA forums and just general web activities are all much slower on my WP7. I can’t think of any reason this would be true but it almost seems like it’s not using my wireless for everything.   Pros: * It’s pretty – the phone is really gorgeous. I loved the form of my Nexus One by the HTC HD7 is just as pretty, maybe even prettier! It’s got a nice large, bright screen. It feels good in my hand. And it even has a little kickstand to set the phone up for movie watching. Definitely a gorgeous phone. * LIVE integration – I lost a lot of nice integration with Google services but I gained a lot of integration with LIVE services that I also use. Now I can see when I get new GMail messages AND Hotmail messages. And having the Xbox LIVE integration is admittedly cool as well. * Tile notification rock – The Windows Phone 7 commercials are TRYING to get this message out but they’re doing a really poor job of this. Tile notifications really do save you from your phone. I have a whole little mini-informational dashboard at a glance. I unlock my phone and at a glace I can see new IMs, new mail messages, software updates etc. All just letting me know in the tiles I have arranged. That’s pretty cool. * The interface works really well – I feel super hip and cool swiping and sliding things around on my Windows Phone 7. Everything works that way and it’s great and fast and really good looking. I’m all about me feeling cool. * I’m gaming more – I had gotten a few games on my Nexus One but there really weren’t a lot of good developers flocking to the service. Just browsing through the Windows Phone 7 marketplace I’m already seeing a ton of games I want to try and buy. And I sat down and bet Pixel Man 0 just yesterday on my phone. I’m already gaming more than I did on my Nexus One. * Netflix integration is fantastic - It works just like it does on my Xbox 360 and I love having this feature on my phone. * It’s basically a Zune – I’ve been taking my Zune to work and listening to music off of that while I code. I no longer need to take it with me, now I just sync songs onto my phone and it’s my new Zune. I freaking love that. One less device to carry around.   All in all my cons have really little to do with the phone (just the buttons and the web browsing) and more to do with the applications needing to catch up a bit to what I’m used to. And the Pros are things that ARE phone specific so I’m seeing that as a good sign that I’m going to be very happy with my Windows Phone 7. So Wifey is happy having her Nexus One again, I’m happy with my new Windows Phone 7. Life is good. Now I just need to make a game to pay for it….

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• Working with Timelines with LINQ to Twitter

  - by Joe Mayo

  When first working with the Twitter API, I thought that using SinceID would be an effective way to page through timelines. In practice it doesn’t work well for various reasons. To explain why, Twitter published an excellent document that is a must-read for anyone working with timelines: Twitter Documentation: Working with Timelines This post shows how to implement the recommended strategies in that document by using LINQ to Twitter. You should read the document in it’s entirety before moving on because my explanation will start at the bottom and work back up to the top in relation to the Twitter document. What follows is an explanation of SinceID, MaxID, and how they come together to help you efficiently work with Twitter timelines. The Role of SinceID Specifying SinceID says to Twitter, “Don’t return tweets earlier than this”. What you want to do is store this value after every timeline query set so that it can be reused on the next set of queries.  The next section will explain what I mean by query set, but a quick explanation is that it’s a loop that gets all new tweets. The SinceID is a backstop to avoid retrieving tweets that you already have. Here’s some initialization code that includes a variable named sinceID that will be used to populate the SinceID property in subsequent queries: // last tweet processed on previous query set ulong sinceID = 210024053698867204; ulong maxID; const int Count = 10; var statusList = new List<status>(); Here, I’ve hard-coded the sinceID variable, but this is where you would initialize sinceID from whatever storage you choose (i.e. a database). The first time you ever run this code, you won’t have a value from a previous query set. Initially setting it to 0 might sound like a good idea, but what if you’re querying a timeline with lots of tweets? Because of the number of tweets and rate limits, your query set might take a very long time to run. A caveat might be that Twitter won’t return an entire timeline back to Tweet #0, but rather only go back a certain period of time, the limits of which are documented for individual Twitter timeline API resources. So, to initialize SinceID at too low of a number can result in a lot of initial tweets, yet there is a limit to how far you can go back. What you’re trying to accomplish in your application should guide you in how to initially set SinceID. I have more to say about SinceID later in this post. The other variables initialized above include the declaration for MaxID, Count, and statusList. The statusList variable is a holder for all the timeline tweets collected during this query set. You can set Count to any value you want as the largest number of tweets to retrieve, as defined by individual Twitter timeline API resources. To effectively page results, you’ll use the maxID variable to set the MaxID property in queries, which I’ll discuss next. Initializing MaxID On your first query of a query set, MaxID will be whatever the most recent tweet is that you get back. Further, you don’t know what MaxID is until after the initial query. The technique used in this post is to do an initial query and then use the results to figure out what the next MaxID will be.  Here’s the code for the initial query: var userStatusResponse = (from tweet in twitterCtx.Status where tweet.Type == StatusType.User && tweet.ScreenName == "JoeMayo" && tweet.SinceID == sinceID && tweet.Count == Count select tweet) .ToList(); statusList.AddRange(userStatusResponse); // first tweet processed on current query maxID = userStatusResponse.Min( status => ulong.Parse(status.StatusID)) - 1; The query above sets both SinceID and Count properties. As explained earlier, Count is the largest number of tweets to return, but the number can be less. A couple reasons why the number of tweets that are returned could be less than Count include the fact that the user, specified by ScreenName, might not have tweeted Count times yet or might not have tweeted at least Count times within the maximum number of tweets that can be returned by the Twitter timeline API resource. Another reason could be because there aren’t Count tweets between now and the tweet ID specified by sinceID. Setting SinceID constrains the results to only those tweets that occurred after the specified Tweet ID, assigned via the sinceID variable in the query above. The statusList is an accumulator of all tweets receive during this query set. To simplify the code, I left out some logic to check whether there were no tweets returned. If  the query above doesn’t return any tweets, you’ll receive an exception when trying to perform operations on an empty list. Yeah, I cheated again. Besides querying initial tweets, what’s important about this code is the final line that sets maxID. It retrieves the lowest numbered status ID in the results. Since the lowest numbered status ID is for a tweet we already have, the code decrements the result by one to keep from asking for that tweet again. Remember, SinceID is not inclusive, but MaxID is. The maxID variable is now set to the highest possible tweet ID that can be returned in the next query. The next section explains how to use MaxID to help get the remaining tweets in the query set. Retrieving Remaining Tweets Earlier in this post, I defined a term that I called a query set. Essentially, this is a group of requests to Twitter that you perform to get all new tweets. A single query might not be enough to get all new tweets, so you’ll have to start at the top of the list that Twitter returns and keep making requests until you have all new tweets. The previous section showed the first query of the query set. The code below is a loop that completes the query set: do { // now add sinceID and maxID userStatusResponse = (from tweet in twitterCtx.Status where tweet.Type == StatusType.User && tweet.ScreenName == "JoeMayo" && tweet.Count == Count && tweet.SinceID == sinceID && tweet.MaxID == maxID select tweet) .ToList(); if (userStatusResponse.Count > 0) { // first tweet processed on current query maxID = userStatusResponse.Min( status => ulong.Parse(status.StatusID)) - 1; statusList.AddRange(userStatusResponse); } } while (userStatusResponse.Count != 0 && statusList.Count < 30); Here we have another query, but this time it includes the MaxID property. The SinceID property prevents reading tweets that we’ve already read and Count specifies the largest number of tweets to return. Earlier, I mentioned how it was important to check how many tweets were returned because failing to do so will result in an exception when subsequent code runs on an empty list. The code above protects against this problem by only working with the results if Twitter actually returns tweets. Reasons why there wouldn’t be results include: if the first query got all the new tweets there wouldn’t be more to get and there might not have been any new tweets between the SinceID and MaxID settings of the most recent query. The code for loading the returned tweets into statusList and getting the maxID are the same as previously explained. The important point here is that MaxID is being reset, not SinceID. As explained in the Twitter documentation, paging occurs from the newest tweets to oldest, so setting MaxID lets us move from the most recent tweets down to the oldest as specified by SinceID. The two loop conditions cause the loop to continue as long as tweets are being read or a max number of tweets have been read.  Logically, you want to stop reading when you’ve read all the tweets and that’s indicated by the fact that the most recent query did not return results. I put the check to stop after 30 tweets are reached to keep the demo from running too long – in the console the response scrolls past available buffer and I wanted you to be able to see the complete output. Yet, there’s another point to be made about constraining the number of items you return at one time. The Twitter API has rate limits and making too many queries per minute will result in an error from twitter that LINQ to Twitter raises as an exception. To use the API properly, you’ll have to ensure you don’t exceed this threshold. Looking at the statusList.Count as done above is rather primitive, but you can implement your own logic to properly manage your rate limit. Yeah, I cheated again. Summary Now you know how to use LINQ to Twitter to work with Twitter timelines. After reading this post, you have a better idea of the role of SinceID - the oldest tweet already received. You also know that MaxID is the largest tweet ID to retrieve in a query. Together, these settings allow you to page through results via one or more queries. You also understand what factors affect the number of tweets returned and considerations for potential error handling logic. The full example of the code for this post is included in the downloadable source code for LINQ to Twitter.   @JoeMayo

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• Displaylink USB show "Logo / Loading" on monitor

  - by Ken Le

  I tried with this problem for 2 years already. LOL, today, I install Ubuntu for I have to resolve it or I will back to stupid Windows 7. First, I have 3 monitors. My graphic card is support dual ( ATI Radeon ), so I have no problem on extend those multi monitor on VGA and DVI. The 3rd monitor is Displaylink USB. After installed everything required, when I reboot, the displaylink monitor show "Ubuntu ...." like logo / loading screen. I go to System Display , Detect monitor, it only show my 1st and 2nd, NO 3RD Displaylink. I can move my mouse between those 1st & 2nd, but the 3rd is only show the Ubuntu Screen. I press Ctrl+Alt+1, then screen switch to Displaylink USB 3RD monitor, but its "Terminal" not a desktop. Then I press Ctrl+Alt+7 , the screen switch back to my 1st, 2nd, and the displaylink 3rd is witch back to Logo / Ubuntu again. This is my /etc/X11/xorg.conf : Section "ServerLayout" Identifier "X.org Configured" Screen 0 "aticonfig-Screen[0]-0" 0 0 Screen 1 "DisplayLinkScreen" Leftof "aticonfig-Screen[0]-0" InputDevice "Mouse0" "CorePointer" InputDevice "Keyboard0" "CoreKeyboard" EndSection Section "Files" ModulePath "/usr/lib/xorg/modules" FontPath "/usr/share/fonts/X11/misc" FontPath "/usr/share/fonts/X11/cyrillic" FontPath "/usr/share/fonts/X11/100dpi/:unscaled" FontPath "/usr/share/fonts/X11/75dpi/:unscaled" FontPath "/usr/share/fonts/X11/Type1" FontPath "/usr/share/fonts/X11/100dpi" FontPath "/usr/share/fonts/X11/75dpi" FontPath "/var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType" FontPath "built-ins" EndSection Section "Module" Load "glx" Load "dri2" Load "dbe" Load "dri" Load "record" Load "extmod" EndSection Section "InputDevice" Identifier "Keyboard0" Driver "kbd" EndSection Section "InputDevice" Identifier "Mouse0" Driver "mouse" Option "Protocol" "auto" Option "Device" "/dev/input/mice" Option "ZAxisMapping" "4 5 6 7" EndSection Section "Monitor" Identifier "aticonfig-Monitor[0]-0" Option "VendorName" "ATI Proprietary Driver" Option "ModelName" "Generic Autodetecting Monitor" Option "DPMS" "true" EndSection Section "Monitor" Identifier "DisplayLinkMonitor" EndSection Section "Monitor" Identifier "0-DFP1" Option "VendorName" "ATI Proprietary Driver" Option "ModelName" "Generic Autodetecting Monitor" Option "DPMS" "true" Option "PreferredMode" "1680x1050" Option "TargetRefresh" "60" Option "Position" "0 0" Option "Rotate" "normal" Option "Disable" "false" EndSection Section "Monitor" Identifier "0-CRT2" Option "VendorName" "ATI Proprietary Driver" Option "ModelName" "Generic Autodetecting Monitor" Option "DPMS" "true" Option "PreferredMode" "1920x1080" Option "TargetRefresh" "60" Option "Position" "1680 0" Option "Rotate" "normal" Option "Disable" "false" EndSection Section "Device" ### Available Driver options are:- ### Values: <i>: integer, <f>: float, <bool>: "True"/"False", ### <string>: "String", <freq>: "<f> Hz/kHz/MHz", ### <percent>: "<f>%" ### [arg]: arg optional #Option "NoAccel" # [<bool>] #Option "SWcursor" # [<bool>] #Option "Dac6Bit" # [<bool>] #Option "Dac8Bit" # [<bool>] #Option "BusType" # [<str>] #Option "CPPIOMode" # [<bool>] #Option "CPusecTimeout" # <i> #Option "AGPMode" # <i> #Option "AGPFastWrite" # [<bool>] #Option "AGPSize" # <i> #Option "GARTSize" # <i> #Option "RingSize" # <i> #Option "BufferSize" # <i> #Option "EnableDepthMoves" # [<bool>] #Option "EnablePageFlip" # [<bool>] #Option "NoBackBuffer" # [<bool>] #Option "DMAForXv" # [<bool>] #Option "FBTexPercent" # <i> #Option "DepthBits" # <i> #Option "PCIAPERSize" # <i> #Option "AccelDFS" # [<bool>] #Option "IgnoreEDID" # [<bool>] #Option "CustomEDID" # [<str>] #Option "DisplayPriority" # [<str>] #Option "PanelSize" # [<str>] #Option "ForceMinDotClock" # <freq> #Option "ColorTiling" # [<bool>] #Option "VideoKey" # <i> #Option "RageTheatreCrystal" # <i> #Option "RageTheatreTunerPort" # <i> #Option "RageTheatreCompositePort" # <i> #Option "RageTheatreSVideoPort" # <i> #Option "TunerType" # <i> #Option "RageTheatreMicrocPath" # <str> #Option "RageTheatreMicrocType" # <str> #Option "ScalerWidth" # <i> #Option "RenderAccel" # [<bool>] #Option "SubPixelOrder" # [<str>] #Option "ClockGating" # [<bool>] #Option "VGAAccess" # [<bool>] #Option "ReverseDDC" # [<bool>] #Option "LVDSProbePLL" # [<bool>] #Option "AccelMethod" # <str> #Option "DRI" # [<bool>] #Option "ConnectorTable" # <str> #Option "DefaultConnectorTable" # [<bool>] #Option "DefaultTMDSPLL" # [<bool>] #Option "TVDACLoadDetect" # [<bool>] #Option "ForceTVOut" # [<bool>] #Option "TVStandard" # <str> #Option "IgnoreLidStatus" # [<bool>] #Option "DefaultTVDACAdj" # [<bool>] #Option "Int10" # [<bool>] #Option "EXAVSync" # [<bool>] #Option "ATOMTVOut" # [<bool>] #Option "R4xxATOM" # [<bool>] #Option "ForceLowPowerMode" # [<bool>] #Option "DynamicPM" # [<bool>] #Option "NewPLL" # [<bool>] #Option "ZaphodHeads" # <str> Identifier "Card0" Driver "radeon" BusID "PCI:5:0:0" EndSection Section "Device" ### Available Driver options are:- ### Values: <i>: integer, <f>: float, <bool>: "True"/"False", ### <string>: "String", <freq>: "<f> Hz/kHz/MHz", ### <percent>: "<f>%" ### [arg]: arg optional #Option "ShadowFB" # [<bool>] #Option "Rotate" # <str> #Option "fbdev" # <str> #Option "debug" # [<bool>] Identifier "Card1" Driver "fbdev" BusID "PCI:5:0:0" EndSection Section "Device" ### Available Driver options are:- ### Values: <i>: integer, <f>: float, <bool>: "True"/"False", ### <string>: "String", <freq>: "<f> Hz/kHz/MHz", ### <percent>: "<f>%" ### [arg]: arg optional #Option "ShadowFB" # [<bool>] #Option "DefaultRefresh" # [<bool>] #Option "ModeSetClearScreen" # [<bool>] Identifier "Card2" Driver "vesa" BusID "PCI:5:0:0" EndSection Section "Device" Identifier "aticonfig-Device[0]-0" Driver "fglrx" Option "Monitor-DFP1" "0-DFP1" Option "Monitor-CRT2" "0-CRT2" BusID "PCI:5:0:0" EndSection Section "Device" Identifier "DisplayLinkDevice" Driver "displaylink" Option "fbdev" "/dev/fb1" Option "ShadowFB" "off" EndSection Section "Screen" Identifier "aticonfig-Screen[0]-0" Device "aticonfig-Device[0]-0" DefaultDepth 24 SubSection "Display" Viewport 0 0 Virtual 3600 1920 Depth 24 EndSubSection EndSection Section "Screen" Identifier "DisplayLinkScreen" Device "DisplayLinkDevice" Monitor "DisplayLinkMonitor" DefaultDepth 24 SubSection "Display" Depth 24 Modes "1920x1080" EndSubSection EndSection

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• Looking into the jQuery LazyLoad Plugin

  - by nikolaosk

  I have been using JQuery for a couple of years now and it has helped me to solve many problems on the client side of web development.  You can find all my posts about JQuery in this link. In this post I will be providing you with a hands-on example on the JQuery LazyLoad Plugin.If you want you can have a look at this post, where I describe the JQuery Cycle Plugin.You can find another post of mine talking about the JQuery Carousel Lite Plugin here. Another post of mine regarding the JQuery Image Zoom Plugin can be found here. You can have a look at the JQuery Overlays Plugin here . There are times when when I am asked to create a very long page with lots of images.My first thought is to enable paging on the proposed page. Imagine that we have 60 images on a page. There are performance concerns when we have so many images on a page. Paging can solve that problem if I am allowed to place only 5 images on a page.Sometimes the customer does not like the idea of the paging.Believe it or not some people find the idea of paging not attractive at all.In that case I need a way to only load the initial set of images and as the user scrolls down the page to load the rest.So as someone scrolls down new requests are made to the server and more images are fetched. I can accomplish that with the jQuery LazyLoad Plugin.This is just a plugin that delays loading of images in long web pages.The images that are outside of the viewport (visible part of web page) won't be loaded before the user scrolls to them. Using jQuery LazyLoad Plugin on long web pages containing many large images makes the page load faster. In this hands-on example I will be using Expression Web 4.0.This application is not a free application. You can use any HTML editor you like. You can use Visual Studio 2012 Express edition. You can download it here.  You can download this plugin from this link. I launch Expression Web 4.0 and then I type the following HTML markup (I am using HTML 5)<!DOCTYPE html><html lang="en">  <head>    <title>Liverpool Legends</title>    <script type="text/javascript" src="jquery-1.8.3.min.js"></script>        <script type="text/javascript" src="jquery.lazyload.min.js" ></script></head>  <body>    <header>                <h1>Liverpool Legends</h1>    </header>        <div id="main">             <img src="barnes.JPG" width="800" height="1100" /><p />        <img src="dalglish.JPG" width="800" height="1100" /><p />                <img class="LiverpoolImage" src="loader.gif" data-original="fans.JPG" width="1200" height="900" /><p />        <img class="LiverpoolImage" src="loader.gif" data-original="lfc.JPG" width="1000" height="700" /><p />        <img class="LiverpoolImage" src="loader.gif" data-original="Liverpool-players.JPG" width="1100" height="900" /><p />        <img class="LiverpoolImage" src="loader.gif" data-original="steven_gerrard.JPG" width="1110" height="1000" /><p />        <img class="LiverpoolImage" src="loader.gif" data-original="robbie.JPG" width="1200" height="1000" /><p />          </div>            <footer>        <p>All Rights Reserved</p>      </footer>                    <script type="text/javascript">                $(function () {                    $("img.LiverpoolImage").lazyload();                });        </script>     </body>  </html> This is a very simple markup. I have  added references to the JQuery library (current version is 1.8.3) and the JQuery LazyLoad Plugin. Firstly, I add two images         <img src="barnes.JPG" width="800" height="1100" /><p />        <img src="dalglish.JPG" width="800" height="1100" /><p />  that will load immediately as soon as the page loads. Then I add the images that will not load unless they become active in the viewport. I have all my img tags pointing the src attribute towards a placeholder image. I’m using a blank 1×1 px grey image,loader.gif.The five images that will load as the user scrolls down the page follow.         <img class="LiverpoolImage" src="loader.gif" data-original="fans.JPG" width="1200" height="900" /><p />        <img class="LiverpoolImage" src="loader.gif" data-original="lfc.JPG" width="1000" height="700" /><p />        <img class="LiverpoolImage" src="loader.gif" data-original="Liverpool-players.JPG" width="1100" height="900" /><p />        <img class="LiverpoolImage" src="loader.gif" data-original="steven_gerrard.JPG" width="1110" height="1000" /><p />        <img class="LiverpoolImage" src="loader.gif" data-original="robbie.JPG" width="1200" height="1000" /><p /> Then we need to rename the image src to point towards the proper image placeholder. The full image URL goes into the data-original attribute.The Javascript code that makes it all happen follows. We need to make a call to the JQuery LazyLoad Plugin. We add the script just before we close the body element.         <script type="text/javascript">                $(function () {                    $("img.LiverpoolImage").lazyload();                });        </script>We can change the code above to incorporate some effects.          <script type="text/javascript">  $("img.LiverpoolImage").lazyload({    effect: "fadeIn"  });    </script> That is all I need to write to achieve lazy loading. It it true that you can do so much with less!!I view my simple page in Internet Explorer 10 and it works as expected. I have tested this simple solution in all major browsers and it works fine. You can test it yourself and see the results in your favorite browser. Hope it helps!!!

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• Are your personal insecurities screwing up your internal communications?

  - by Lucy Boyes

  I do some internal comms as part of my job. Quite a lot of it involves talking to people about stuff. I’m spending the next couple of weeks talking to lots of people about internal comms itself, because we haven’t done a lot of audience/user feedback gathering, and it turns out that if you talk to people about how they feel and what they think, you get some pretty interesting insights (and an idea of what to do next that isn’t just based on guesswork and generalising from self). Three things keep coming up from talking to people about what we suck at  in terms of internal comms. And, as far as I can tell, they’re all examples where personal insecurity on the part of the person doing the communicating makes the experience much worse for the people on the receiving end. 1. Spending time telling people how you’re going to do something, not what you’re doing and why Imagine you’ve got to give an update to a lot of people who don’t work in your area or department but do have an interest in what you’re doing (either because they want to know because they’re curious or because they need to know because it’s going to affect their work too). You don’t want to look bad at your job. You want to make them think you’ve got it covered – ideally because you do*. And you want to reassure them that there’s lots of exciting work going on in your area to make [insert thing of choice] happen to [insert thing of choice] so that [insert group of people] will be happy. That’s great! You’re doing a good job and you want to tell people about it. This is good comms stuff right here. However, you’re slightly afraid you might secretly be stupid or lazy or incompetent. And you’re exponentially more afraid that the people you’re talking to might think you’re stupid or lazy or incompetent. Or pointless. Or not-adding-value. Or whatever the thing that’s the worst possible thing to be in your company is. So you open by mentioning all the stuff you’re going to do, spending five minutes or so making sure that everyone knows that you’re DOING lots of STUFF. And the you talk for the rest of the time about HOW you’re going to do the stuff, because that way everyone will know that you’ve thought about this really hard and done tons of planning and had lots of great ideas about process and that you’ve got this one down. That’s the stuff you’ve got to say, right? To prove you’re not fundamentally worthless as a human being? Well, maybe. But probably not. See, the people who need to know how you’re going to do the stuff are the people doing the stuff. And those are the people in your area who you’ve (hopefully-please-for-the-love-of-everything-holy) already talked to in depth about how you’re going to do the thing (because else how could they help do it?). They are the only people who need to know the how**. It’s the difference between strategy and tactics. The people outside of your bubble of stuff-doing need to know the strategy – what it is that you’re doing, why, where you’re going with it, etc. The people on the ground with you need the strategy and the tactics, because else they won’t know how to do the stuff. But the outside people don’t really need the tactics at all. Don’t bother with the how unless your audience needs it. They probably don’t. It might make you feel better about yourself, but it’s much more likely that Bob and Jane are thinking about how long this meeting has gone on for already than how personally impressive and definitely-not-an-idiot you are for knowing how you’re going to do some work. Feeling marginally better about yourself (but, let’s face it, still insecure as heck) is not worth the cost, which in this case is the alienation of your audience. 2. Talking for too long about stuff This is kinda the same problem as the previous problem, only much less specific, and I’ve more or less covered why it’s bad already. Basic motivation: to make people think you’re not an idiot. What you do: talk for a very long time about what you’re doing so as to make it sound like you know what you’re doing and lots about it. What your audience wants: the shortest meaningful update. Some of this is a kill your darlings problem – the stuff you’re doing that seems really nifty to you seems really nifty to you, and thus you want to share it with everyone to show that you’re a smart person who thinks up nifty things to do. The downside to this is that it’s mostly only interesting to you – if other people don’t need to know, they likely also don’t care. Think about how you feel when someone is talking a lot to you about a lot of stuff that they’re doing which is at best tangentially interesting and/or relevant. You’re probably not thinking that they’re really smart and clearly know what they’re doing (unless they’re talking a lot and being really engaging about it, which is not the same as talking a lot). You’re probably thinking about something totally unrelated to the thing they’re talking about. Or the fact that you’re bored. You might even – and this is the opposite of what they’re hoping to achieve by talking a lot about stuff – be thinking they’re kind of an idiot. There’s another huge advantage to paring down what you’re trying to say to the barest possible points – it clarifies your thinking. The lightning talk format, as well as other formats which limit the time and/or number of slides you have to say a thing, are really good for doing this. It’s incredibly likely that your audience in this case (the people who need to know some things about your thing but not all the things about your thing) will get everything they need to know from five minutes of you talking about it, especially if trying to condense ALL THE THINGS into a five-minute talk has helped you get clear in your own mind what you’re doing, what you’re trying to say about what you’re doing and why you’re doing it. The bonus of this is that by being clear in your thoughts and in what you say, and in not taking up lots of people’s time to tell them stuff they don’t really need to know, you actually come across as much, much smarter than the person who talks for half an hour or more about things that are semi-relevant at best. 3. Waiting until you’ve got every detail sorted before announcing a big change to the people affected by it This is the worst crime on the list. It’s also human nature. Announcing uncertainty – that something important is going to happen (big reorganisation, product getting canned, etc.) but you’re not quite sure what or when or how yet – is scary. There are risks to it. Uncertainty makes people anxious. It might even paralyse them. You can’t run a business while you’re figuring out what to do if you’ve paralysed everyone with fear over what the future might bring. And you’re scared that they might think you’re not the right person to be in charge of [thing] if you don’t even know what you’re doing with it. Best not to say anything until you know exactly what’s going to happen and you can reassure them all, right? Nope. The people who are going to be affected by whatever it is that you don’t quite know all the details of yet aren’t stupid***. You wouldn’t have hired them if they were. They know something’s up because you’ve got your guilty face on and you keep pulling people into meeting rooms and looking vaguely worried. Here’s the deal: it’s a lot less stressful for everyone (including you) if you’re up front from the beginning. We took this approach during a recent company-wide reorganisation and got really positive feedback. People would much, much rather be told that something is going to happen but you’re not entirely sure what it is yet than have you wait until it’s all fixed up and then fait accompli the heck out of them. They will tell you this themselves if you ask them. And here’s why: by waiting until you know exactly what’s going on to communicate, you remove any agency that the people that the thing is going to happen to might otherwise have had. I know you’re scared that they might get scared – and that’s natural and kind of admirable – but it’s also patronising and infantilising. Ask someone whether they’d rather work on a project which has an openly uncertain future from the beginning, or one where everything’s great until it gets shut down with no forewarning, and very few people are going to tell you they’d prefer the latter. Uncertainty is humanising. It’s you admitting that you don’t have all the answers, which is great, because no one does. It allows you to be consultative – you can actually ask other people what they think and how they feel and what they’d like to do and what they think you should do, and they’ll thank you for it and feel listened to and respected as people and colleagues. Which is a really good reason to start talking to them about what’s going on as soon as you know something’s going on yourself. All of the above assumes you actually care about talking to the people who work with you and for you, and that you’d like to do the right thing by them. If that’s not the case, you can cheerfully disregard the advice here, but if it is, you might want to think about the ways above – and the inevitable countless other ways – that making internal communication about you and not about your audience could actually be doing the people you’re trying to communicate with a huge disservice. So take a deep breath and talk. For five minutes or so. About the important things. Not the other things. As soon as you possibly can. And you’ll be fine.   *Of course you do. You’re good at your job. Don’t worry. **This might not always be true, but it is most of the time. Other people who need to know the how will either be people who you’ve already identified as needing-to-know and thus part of the same set as the people in you’re area you’ve already discussed this with, or else they’ll ask you. But don’t bring this stuff up unless someone asks for it, because most of the people in the audience really don’t care and you’re wasting their time. ***I mean, they might be. But let’s give them the benefit of the doubt and assume they’re not.

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• Making Those PanelBoxes Behave

  - by Duncan Mills

  I have a little problem to solve earlier this week - misbehaving <af:panelBox> components... What do I mean by that? Well here's the scenario, I have a page fragment containing a set of panelBoxes arranged vertically. As it happens, they are stamped out in a loop but that does not really matter. What I want to be able to do is to provide the user with a simple UI to close and open all of the panelBoxes in concert. This could also apply to showDetailHeader and similar items with a disclosed attrubute, but in this case it's good old panelBoxes.  Ok, so the basic solution to this should be self evident. I can set up a suitable scoped managed bean that the panelBoxes all refer to for their disclosed attribute state. Then the open all / close commandButtons in the UI can simply set the state of that bean for all the panelBoxes to pick up via EL on their disclosed attribute. Sound OK? Well that works basically without a hitch, but turns out that there is a slight problem and this is where the framework is attempting to be a little too helpful. The issue is that is the user manually discloses or hides a panelBox then that will override the value that the EL is setting. So for example. I start the page with all panelBoxes collapsed, all set by the EL state I'm storing on the session I manually disclose panelBox no 1. I press the Expand All button - all works as you would hope and all the panelBoxes are now disclosed, including of course panelBox 1 which I just expanded manually. Finally I press the Collapse All button and everything collapses except that first panelBox that I manually disclosed.  The problem is that the component remembers this manual disclosure and that overrides the value provided by the expression. If I change the viewId (navigate away and back) then the panelBox will start to behave again, until of course I touch it again! Now, the more astute amoungst you would think (as I did) Ah, sound like the MDS personalizaton stuff is getting in the way and the solution should simply be to set the dontPersist attribute to disclosed | ALL. Alas this does not fix the issue.  After a little noodling on the best way to approach this I came up with a solution that works well, although if you think of an alternative way do let me know. The principle is simple. In the disclosureListener for the panelBox I take a note of the clientID of the panelBox component that has been touched by the user along with the state. This all gets stored in a Map of Booleans in ViewScope which is keyed by clientID and stores the current disclosed state in the Boolean value.  The listener looks like this (it's held in a request scope backing bean for the page): public void handlePBDisclosureEvent(DisclosureEvent disclosureEvent) { String clientId = disclosureEvent.getComponent().getClientId(FacesContext.getCurrentInstance()); boolean state = disclosureEvent.isExpanded(); pbState.addTouchedPanelBox(clientId, state); } The pbState variable referenced here is a reference to the bean which will hold the state of the panelBoxes that lives in viewScope (recall that everything is re-set when the viewid is changed so keeping this in viewScope is just fine and cleans things up automatically). The addTouchedPanelBox() method looks like this: public void addTouchedPanelBox(String clientId, boolean state) { //create the cache if needed this is just a Map<String,Boolean> if (_touchedPanelBoxState == null) { _touchedPanelBoxState = new HashMap<String, Boolean>(); } // Simply put / replace _touchedPanelBoxState.put(clientId, state); } So that's the first part, we now have a record of every panelBox that the user has touched. So what do we do when the Collapse All or Expand All buttons are pressed? Here we do some JavaScript magic. Basically for each clientID that we have stored away, we issue a client side disclosure event from JavaScript - just as if the user had gone back and changed it manually. So here's the Collapse All button action: public String CloseAllAction() { submitDiscloseOverride(pbState.getTouchedClientIds(true), false); _uiManager.closeAllBoxes(); return null; }  The _uiManager.closeAllBoxes() method is just manipulating the master-state that all of the panelBoxes are bound to using EL. The interesting bit though is the line:  submitDiscloseOverride(pbState.getTouchedClientIds(true), false); To break that down, the first part is a call to that viewScoped state holder to ask for a list of clientIDs that need to be "tweaked": public String getTouchedClientIds(boolean targetState) { StringBuilder sb = new StringBuilder(); if (_touchedPanelBoxState != null && _touchedPanelBoxState.size() > 0) { for (Map.Entry<String, Boolean> entry : _touchedPanelBoxState.entrySet()) { if (entry.getValue() == targetState) { if (sb.length() > 0) { sb.append(','); } sb.append(entry.getKey()); } } } return sb.toString(); } You'll notice that this method only processes those panelBoxes that will be in the wrong state and returns those as a comma separated list. This is then processed by the submitDiscloseOverride() method: private void submitDiscloseOverride(String clientIdList, boolean targetDisclosureState) { if (clientIdList != null && clientIdList.length() > 0) { FacesContext fctx = FacesContext.getCurrentInstance(); StringBuilder script = new StringBuilder(); script.append("overrideDiscloseHandler('"); script.append(clientIdList); script.append("',"); script.append(targetDisclosureState); script.append(");"); Service.getRenderKitService(fctx, ExtendedRenderKitService.class).addScript(fctx, script.toString()); } } This method constructs a JavaScript command to call a routine called overrideDiscloseHandler() in a script attached to the page (using the standard <af:resource> tag). That method parses out the list of clientIDs and sends the correct message to each one: function overrideDiscloseHandler(clientIdList, newState) { AdfLogger.LOGGER.logMessage(AdfLogger.INFO, "Disclosure Hander newState " + newState + " Called with: " + clientIdList); //Parse out the list of clientIds var clientIdArray = clientIdList.split(','); for (var i = 0; i < clientIdArray.length; i++){ var panelBox = flipPanel = AdfPage.PAGE.findComponentByAbsoluteId(clientIdArray[i]); if (panelBox.getComponentType() == "oracle.adf.RichPanelBox"){ panelBox.broadcast(new AdfDisclosureEvent(panelBox, newState)); } }  }  So there you go. You can see how, with a few tweaks the same code could be used for other components with disclosure that might suffer from the same problem, although I'd point out that the behavior I'm working around here us usually desirable. You can download the running example (11.1.2.2) from here. 

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• How do I make a jumping dolphin rotate realistically?

  - by Johnny

  I want to program a dolphin that jumps and rotates like a real dolphin. Jumping is not the problem, but I don't know how to make the rotation. At the moment, my dolphin rotates a little weird. But I want that it rotates like a real dolphin does. How can I improve the rotation? public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; Texture2D image, water; float Gravity = 5.0F; float Acceleration = 20.0F; Vector2 Position = new Vector2(1200,720); Vector2 Velocity; float rotation = 0; SpriteEffects flip; Vector2 Speed = new Vector2(0, 0); public Game1() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; graphics.PreferredBackBufferWidth = 1280; graphics.PreferredBackBufferHeight = 720; } protected override void Initialize() { base.Initialize(); } protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); image = Content.Load<Texture2D>("cartoondolphin"); water = Content.Load<Texture2D>("background"); flip = SpriteEffects.None; } protected override void Update(GameTime gameTime) { float VelocityX = 0f; float VelocityY = 0f; float time = (float)gameTime.ElapsedGameTime.TotalSeconds; KeyboardState kbState = Keyboard.GetState(); if(kbState.IsKeyDown(Keys.Left)) { rotation = 0; flip = SpriteEffects.None; VelocityX += -5f; } if(kbState.IsKeyDown(Keys.Right)) { rotation = 0; flip = SpriteEffects.FlipHorizontally; VelocityX += 5f; } // jump if the dolphin is under water if(Position.Y >= 670) { if (kbState.IsKeyDown(Keys.A)) { if (flip == SpriteEffects.None) { rotation += 0.01f; VelocityY += 40f; } else { rotation -= 0.01f; VelocityY += 40f; } } } else { if (flip == SpriteEffects.None) { rotation -= 0.01f; VelocityY += -10f; } else { rotation += 0.01f; VelocityY += -10f; } } float deltaY = 0; float deltaX = 0; deltaY = Gravity * (float)gameTime.ElapsedGameTime.TotalSeconds; deltaX += VelocityX * (float)gameTime.ElapsedGameTime.TotalSeconds * Acceleration; deltaY += -VelocityY * (float)gameTime.ElapsedGameTime.TotalSeconds * Acceleration; Speed = new Vector2(Speed.X + deltaX, Speed.Y + deltaY); Position += Speed * (float)gameTime.ElapsedGameTime.TotalSeconds; Velocity.X = 0; if (Position.Y + image.Height/2 > graphics.PreferredBackBufferHeight) Position.Y = graphics.PreferredBackBufferHeight - image.Height/2; base.Update(gameTime); } protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); spriteBatch.Begin(); spriteBatch.Draw(water, new Rectangle(0, graphics.PreferredBackBufferHeight -100, graphics.PreferredBackBufferWidth, 100), Color.White); spriteBatch.Draw(image, Position, null, Color.White, rotation, new Vector2(image.Width / 2, image.Height / 2), 1, flip, 1); spriteBatch.End(); base.Draw(gameTime); } } I changed my code a little. But I still have some trouble with the rotation. Here's the entire code. The dolphin looks at the wrong direction if I press the left or right key. For example, it looks down if I press the left key. What is wrong with the rotation? At the beginning, the dolphin looks at the left side, but after I pressed a key it just looks down or up. I deleted the "rotation += 0.01f;" lines in the code. Is that correct? public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; Texture2D image, water; float Gravity = 5.0F; float Acceleration = 20.0F; Vector2 Position = new Vector2(1200,720); Vector2 Velocity; float rotation = 0; SpriteEffects flip; Vector2 Speed = new Vector2(0, 0); Vector2 prevPos; public Game1() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; graphics.PreferredBackBufferWidth = 1280; graphics.PreferredBackBufferHeight = 720; } protected override void Initialize() { base.Initialize(); } protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); image = Content.Load<Texture2D>("cartoondolphin"); water = Content.Load<Texture2D>("background"); flip = SpriteEffects.None; } protected override void Update(GameTime gameTime) { float VelocityX = 0f; float VelocityY = 0f; float time = (float)gameTime.ElapsedGameTime.TotalSeconds; KeyboardState kbState = Keyboard.GetState(); if(kbState.IsKeyDown(Keys.Left)) { flip = SpriteEffects.None; VelocityX += -5f; } if(kbState.IsKeyDown(Keys.Right)) { flip = SpriteEffects.FlipHorizontally; VelocityX += 5f; } rotation = (float)Math.Atan2(Position.X - prevPos.X, Position.Y - prevPos.Y); prevPos = Position; // jump if the dolphin is under water if(Position.Y >= 670) { if (kbState.IsKeyDown(Keys.A)) { if (flip == SpriteEffects.None) { VelocityY += 40f; } else { VelocityY += 40f; } } } else { if (flip == SpriteEffects.None) { VelocityY += -10f; } else { VelocityY += -10f; } } float deltaY = 0; float deltaX = 0; deltaY = Gravity * (float)gameTime.ElapsedGameTime.TotalSeconds; deltaX += VelocityX * (float)gameTime.ElapsedGameTime.TotalSeconds * Acceleration; deltaY += -VelocityY * (float)gameTime.ElapsedGameTime.TotalSeconds * Acceleration; Speed = new Vector2(Speed.X + deltaX, Speed.Y + deltaY); Position += Speed * (float)gameTime.ElapsedGameTime.TotalSeconds; Velocity.X = 0; if (Position.Y + image.Height/2 > graphics.PreferredBackBufferHeight) Position.Y = graphics.PreferredBackBufferHeight - image.Height/2; base.Update(gameTime); } protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); spriteBatch.Begin(); spriteBatch.Draw(water, new Rectangle(0, graphics.PreferredBackBufferHeight -100, graphics.PreferredBackBufferWidth, 100), Color.White); spriteBatch.Draw(image, Position, null, Color.White, rotation, new Vector2(image.Width / 2, image.Height / 2), 1, flip, 1); spriteBatch.End(); base.Draw(gameTime); } }

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• Unable to list contents/remove directory (linux ext3)

  - by RedKrieg

  System is CentOS5 x86_64, completely up to date. I've got a folder that can't be listed (ls just hangs, eating memory until it is killed). The directory size is nearly 500k: root@server [/home/user/public_html/domain.com/wp-content/uploads/2010/03]# stat . File: `.' Size: 458752 Blocks: 904 IO Block: 4096 directory Device: 812h/2066d Inode: 44499071 Links: 2 Access: (0755/drwxr-xr-x) Uid: ( 3292/ user) Gid: ( 3287/ user) Access: 2012-06-29 17:31:47.000000000 -0400 Modify: 2012-10-23 14:41:58.000000000 -0400 Change: 2012-10-23 14:41:58.000000000 -0400 I can see the file names if I use ls -1f, but it just repeats the same 48 files ad infinitum, all of which have non-ascii characters somewhere in the file name: La-critic\363-al-servicio-la-privacidad-300x160.jpg When I try to access the files (say to copy them or remove them) I get messages like the following: lstat("/home/user/public_html/domain.com/wp-content/uploads/2010/03/Sebast\355an-Pi\361era-el-balc\363n-150x120.jpg", 0x7fff364c52c0) = -1 ENOENT (No such file or directory) I tried altering the code found on this man page and modified the code to call unlink for each file. I get the same ENOENT error from the unlink call: unlink("/home/user/public_html/domain.com/wp-content/uploads/2010/03/Marca-naci\363n-Madrid-150x120.jpg") = -1 ENOENT (No such file or directory) I also straced a "touch", grabbed the syscalls it makes and replicated them, then tried to unlink the resulting file by name. This works fine, but the folder still contains an entry by the same name after the operation completes and the program runs for an arbitrarily long time (strace output ended up at 20GB after 5 minutes and I stopped the process). I'm stumped on this one, I'd really prefer not to have to take this production machine (hundreds of customers) offline to fsck the filesystem, but I'm leaning toward that being the only option at this point. If anyone's had success using other methods for removing files (by inode number, I can get those with the getdents code) I'd love to hear them. (Yes, I've tried find . -inum <inode> -exec rm -fv {} \; and it still has the problem with unlink returning ENOENT) For those interested, here's the diff between that man page's code and mine. I didn't bother with error checking on mallocs, etc because I'm lazy and this is a one-off: root@server [~]# diff -u listdir-orig.c listdir.c --- listdir-orig.c 2012-10-23 15:10:02.000000000 -0400 +++ listdir.c 2012-10-23 14:59:47.000000000 -0400 @@ -6,6 +6,7 @@ #include <stdlib.h> #include <sys/stat.h> #include <sys/syscall.h> +#include <string.h> #define handle_error(msg) \ do { perror(msg); exit(EXIT_FAILURE); } while (0) @@ -17,7 +18,7 @@ char d_name[]; }; -#define BUF_SIZE 1024 +#define BUF_SIZE 1024*1024*5 int main(int argc, char *argv[]) { @@ -26,11 +27,16 @@ struct linux_dirent *d; int bpos; char d_type; + int deleted; + int file_descriptor; fd = open(argc > 1 ? argv[1] : ".", O_RDONLY | O_DIRECTORY); if (fd == -1) handle_error("open"); + char* full_path; + char* fd_path; + for ( ; ; ) { nread = syscall(SYS_getdents, fd, buf, BUF_SIZE); if (nread == -1) @@ -55,7 +61,24 @@ printf("%4d %10lld %s\n", d->d_reclen, (long long) d->d_off, (char *) d->d_name); bpos += d->d_reclen; + if ( d_type == DT_REG ) + { + full_path = malloc(strlen((char *) d->d_name) + strlen(argv[1]) + 2); //One for the /, one for the \0 + strcpy(full_path, argv[1]); + strcat(full_path, (char *) d->d_name); + + //We're going to try to "touch" the file. + //file_descriptor = open(full_path, O_WRONLY|O_CREAT|O_NOCTTY|O_NONBLOCK, 0666); + //fd_path = malloc(32); //Lazy, only really needs 16 + //sprintf(fd_path, "/proc/self/fd/%d", file_descriptor); + //utimes(fd_path, NULL); + //close(file_descriptor); + deleted = unlink(full_path); + if ( deleted == -1 ) printf("Error unlinking file\n"); + break; //Break on first try + } } + break; //Break on first try } exit(EXIT_SUCCESS);

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• Linux/Apache performance very slow even on local network

  - by klausch

  I have an Ubuntu server machine running Apache and MYSQL. System and version info is as follows: Linux kernel 3.0.0.-12 Apache/2.2.20 MySQL Ver 14.14.Distrib 5.1.58 I am running a few websites on this server, some HTML only, some PHP/MySQL. THe [problem is that response time is very slow, both on static as well as the dynamic sites. Sometimes it takes more than 10 seconds before a response is given, this makes the sites very slow and almost unusable. The problem occurs even when requesting from the local network. I have added the involved subdomains to my /etc/hosts file, and abolve all the problem is not solved by using IP numbers instead of URL's. So there is no DNS lookup issue. I have modified the log format by showing the response times and sometimes a files takes 12 seconds to be served, see the jquery~.js file in the example screenshot. I have no explanation for this extremely long response time, but is is not even the only issue here, some other files takes a long time to be served too, but do not show a long response time in the log file. So probably different tissues are involved here. I cannot find a solution until now, any suggestions??? THanx in advance, Klaas link to screenshot picture from access logfile Some extra configuration info: apache2.conf (comment is removed) LockFile ${APACHE_LOCK_DIR}/accept.lock PidFile ${APACHE_PID_FILE} Timeout 300 KeepAlive On MaxKeepAliveRequests 100 KeepAliveTimeout 5 <IfModule mpm_prefork_module> StartServers 5 MinSpareServers 5 MaxSpareServers 10 MaxClients 150 MaxRequestsPerChild 0 </IfModule> <IfModule mpm_worker_module> StartServers 2 MinSpareThreads 25 MaxSpareThreads 75 ThreadLimit 64 ThreadsPerChild 25 MaxClients 150 MaxRequestsPerChild 0 </IfModule> <IfModule mpm_event_module> StartServers 2 MinSpareThreads 25 MaxSpareThreads 75 ThreadLimit 64 ThreadsPerChild 25 MaxClients 150 MaxRequestsPerChild 0 </IfModule> User ${APACHE_RUN_USER} Group ${APACHE_RUN_GROUP} AccessFileName .htaccess <Files ~ "^\.ht"> Order allow,deny Deny from all Satisfy all </Files> DefaultType text/plain HostnameLookups Off ErrorLog ${APACHE_LOG_DIR}/error.log LogLevel warn Include mods-enabled/*.load Include mods-enabled/*.conf Include httpd.conf Include ports.conf LogFormat "%v:%p %h %l %u %t \"%r\" %>s %O \"%{Referer}i\" \"%{User-Agent}i\"" vhost_combined LogFormat "%h %l %u %t \"%r\" %>s %O \"%{Referer}i\" \"%{User-Agent}i\" %T/%D" combined LogFormat "%h %l %u %t \"%r\" %>s %O" common LogFormat "%{Referer}i -> %U" referer LogFormat "%{User-agent}i" agent Include conf.d/ Include sites-enabled/ And the virtual hostfile for one of the slow sites, in fact it is pretty straightforward... <VirtualHost *:80> ServerAdmin [email protected] ServerSignature EMail ServerName toenjoy.drsklaus.nl DocumentRoot /var/www/toenjoy.drsklaus.nl <Directory /> Options FollowSymLinks AllowOverride None </Directory> <Directory /var/www/toenjoy.drsklaus.nl/> Options Indexes FollowSymLinks MultiViews AllowOverride AuthConfig AuthType Basic AuthName "To Enjoy" AuthUserFile /etc/.htpasswd Require user petraaa Order allow,deny allow from all </Directory> ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/ <Directory "/usr/lib/cgi-bin"> AllowOverride None Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch Order allow,deny Allow from all </Directory> ErrorLog /var/log/apache2/error.log # Possible values include: debug, info, notice, warn, error, crit, # alert, emerg. LogLevel warn CustomLog /var/log/apache2/access.log combined Alias /doc/ "/usr/share/doc/" <Directory "/usr/share/doc/"> Options Indexes MultiViews FollowSymLinks AllowOverride None Order deny,allow Deny from all Allow from 127.0.0.0/255.0.0.0 ::1/128 </Directory> </VirtualHost> And the output of free -m: klaas@ubuntu-server:/etc/apache2$ free -m total used free shared buffers cached Mem: 1997 1401 595 0 144 1017 -/+ buffers/cache: 238 1758 Swap: 2035 0 2035 and I have no indication that swapping occurs on the moments the site is slow. I have runned top and it does not appear to be a CPU issue. I have the impression that the spawning of a apache thread could maybe be the bottleneck but it is just a suggestion. Maybe this gives some extra information! EDIT: The problem seemed to be gone for some time but occurs again! And not only with Apache, also connecting using SSH takes a tremendous time, sometimes it takes up to 15 seconds before the keyphrase is asked for. Also scp works very slowly. The behavious is really unpredoctable and makes the server very hard to use. Any ideas...?

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• FOSUserBundle override mapping to remove need for username

  - by musoNic80

  I want to remove the need for a username in the FOSUserBundle. My users will login using an email address only and I've added real name fields as part of the user entity. I realised that I needed to redo the entire mapping as described here. I think I've done it correctly but when I try to submit the registration form I get the error: "Only field names mapped by Doctrine can be validated for uniqueness." The strange thing is that I haven't tried to assert a unique constraint to anything in the user entity. Here is my full user entity file: <?php // src/MyApp/UserBundle/Entity/User.php namespace MyApp\UserBundle\Entity; use FOS\UserBundle\Model\User as BaseUser; use Doctrine\ORM\Mapping as ORM; use Symfony\Component\Validator\Constraints as Assert; /** * @ORM\Entity * @ORM\Table(name="depbook_user") */ class User extends BaseUser { /** * @ORM\Id * @ORM\Column(type="integer") * @ORM\GeneratedValue(strategy="AUTO") */ protected $id; /** * @ORM\Column(type="string", length=255) * * @Assert\NotBlank(message="Please enter your first name.", groups={"Registration", "Profile"}) * @Assert\MaxLength(limit="255", message="The name is too long.", groups={"Registration", "Profile"}) */ protected $firstName; /** * @ORM\Column(type="string", length=255) * * @Assert\NotBlank(message="Please enter your last name.", groups={"Registration", "Profile"}) * @Assert\MaxLength(limit="255", message="The name is too long.", groups={"Registration", "Profile"}) */ protected $lastName; /** * @ORM\Column(type="string", length=255) * * @Assert\NotBlank(message="Please enter your email address.", groups={"Registration", "Profile"}) * @Assert\MaxLength(limit="255", message="The name is too long.", groups={"Registration", "Profile"}) * @Assert\Email(groups={"Registration"}) */ protected $email; /** * @ORM\Column(type="string", length=255, name="email_canonical", unique=true) */ protected $emailCanonical; /** * @ORM\Column(type="boolean") */ protected $enabled; /** * @ORM\Column(type="string") */ protected $salt; /** * @ORM\Column(type="string") */ protected $password; /** * @ORM\Column(type="datetime", nullable=true, name="last_login") */ protected $lastLogin; /** * @ORM\Column(type="boolean") */ protected $locked; /** * @ORM\Column(type="boolean") */ protected $expired; /** * @ORM\Column(type="datetime", nullable=true, name="expires_at") */ protected $expiresAt; /** * @ORM\Column(type="string", nullable=true, name="confirmation_token") */ protected $confirmationToken; /** * @ORM\Column(type="datetime", nullable=true, name="password_requested_at") */ protected $passwordRequestedAt; /** * @ORM\Column(type="array") */ protected $roles; /** * @ORM\Column(type="boolean", name="credentials_expired") */ protected $credentialsExpired; /** * @ORM\Column(type="datetime", nullable=true, name="credentials_expired_at") */ protected $credentialsExpiredAt; public function __construct() { parent::__construct(); // your own logic } /** * @return string */ public function getFirstName() { return $this->firstName; } /** * @return string */ public function getLastName() { return $this->lastName; } /** * Sets the first name. * * @param string $firstname * * @return User */ public function setFirstName($firstname) { $this->firstName = $firstname; return $this; } /** * Sets the last name. * * @param string $lastname * * @return User */ public function setLastName($lastname) { $this->lastName = $lastname; return $this; } } I've seen various suggestions about this but none of the suggestions seem to work for me. The FOSUserBundle docs are very sparse about what must be a very common request.

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• Need help with setting up comet code

  - by Saif Bechan

  Does anyone know off a way or maybe think its possible to connect Node.js with Nginx http push module to maintain a persistent connection between client and browser. I am new to comet so just don't understand the publishing etc maybe someone can help me with this. What i have set up so far is the following. I downloaded the jQuery.comet plugin and set up the following basic code: Client JavaScript <script type="text/javascript"> function updateFeed(data) { $('#time').text(data); } function catchAll(data, type) { console.log(data); console.log(type); } $.comet.connect('/broadcast/sub?channel=getIt'); $.comet.bind(updateFeed, 'feed'); $.comet.bind(catchAll); $('#kill-button').click(function() { $.comet.unbind(updateFeed, 'feed'); }); </script> What I can understand from this is that the client will keep on listening to the url followed by /broadcast/sub=getIt. When there is a message it will fire updateFeed. Pretty basic and understandable IMO. Nginx http push module config default_type application/octet-stream; sendfile on; keepalive_timeout 65; push_authorized_channels_only off; server { listen 80; location /broadcast { location = /broadcast/sub { set $push_channel_id $arg_channel; push_subscriber; push_subscriber_concurrency broadcast; push_channel_group broadcast; } location = /broadcast/pub { set $push_channel_id $arg_channel; push_publisher; push_min_message_buffer_length 5; push_max_message_buffer_length 20; push_message_timeout 5s; push_channel_group broadcast; } } } Ok now this tells nginx to listen at port 80 for any calls to /broadcast/sub and it will give back any responses sent to /broadcast/pub. Pretty basic also. This part is not so hard to understand, and is well documented over the internet. Most of the time there is a ruby or a php file behind this that does the broadcasting. My idea is to have node.js broadcasting /broadcast/pub. I think this will let me have persistent streaming data from the server to the client without breaking the connection. I tried the long-polling approach with looping the request but I think this will be more efficient. Or is this not going to work. Node.js file Now to create the Node.js i'm lost. First off all I don't know how to have node.js to work in this way. The setup I used for long polling is as follows: var sys = require('sys'), http = require('http'); http.createServer(function (req, res) { res.writeHead(200, {'Content-Type': 'text/html'}); res.write(new Date()); res.close(); seTimeout('',1000); }).listen(8000); This listens to port 8000 and just writes on the response variable. For long polling my nginx.config looked something like this: server { listen 80; server_name _; location / { proxy_pass http://mydomain.com:8080$request_uri; include /etc/nginx/proxy.conf; } } This just redirected the port 80 to 8000 and this worked fine. Does anyone have an idea on how to have Node.js act in a way Comet understands it. Would be really nice and you will help me out a lot. Recources used An example where this is done with ruby instead of Node.js jQuery.comet Nginx HTTP push module homepage Faye: a Comet client and server for Node.js and Rack To use faye I have to install the comet client, but I want to use the one supplied with Nginx. Thats why I don't just use faye. The one nginx uses is much more optimzed. extra Persistant connections Going evented with Node.js

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• How can I use the Boost Graph Library to lay out verticies?

  - by Mike

  I'm trying to lay out vertices using the Boost Graph Library. However, I'm running into some compilation issues which I'm unsure about. Am I using the BGL in an improper manner? My code is: PositionVec position_vec(2); PositionMap position(position_vec.begin(), get(vertex_index, g)); int iterations = 100; double width = 100.0; double height = 100.0; minstd_rand gen; rectangle_topology<> topology(gen, 0, 0, 100, 100); fruchterman_reingold_force_directed_layout(g, position, topology); //Compile fails on this line The diagnostics produced by clang++(I've also tried GCC) are: In file included from test.cpp:2: /Volumes/Data/mike/Downloads/boost_1_43_0/boost/graph/fruchterman_reingold.hpp:95:3: error: no member named 'dimensions' in 'boost::simple_point<double>' BOOST_STATIC_ASSERT (Point::dimensions == 2); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from test.cpp:2: In file included from /Volumes/Data/mike/Downloads/boost_1_43_0/boost/graph/fruchterman_reingold.hpp:13: In file included from /Volumes/Data/mike/Downloads/boost_1_43_0/boost/graph/graph_traits.hpp:15: In file included from /Volumes/Data/mike/Downloads/boost_1_43_0/boost/tuple/tuple.hpp:24: /Volumes/Data/mike/Downloads/boost_1_43_0/boost/static_assert.hpp:118:49: note: instantiated from: sizeof(::boost::STATIC_ASSERTION_FAILURE< BOOST_STATIC_ASSERT_BOOL_CAST( B ) >)>\ ^ In file included from test.cpp:2: /Volumes/Data/mike/Downloads/boost_1_43_0/boost/graph/fruchterman_reingold.hpp:95:3: note: instantiated from: BOOST_STATIC_ASSERT (Point::dimensions == 2); ^ ~~~~~~~ /Volumes/Data/mike/Downloads/boost_1_43_0/boost/graph/fruchterman_reingold.hpp:95:31: note: instantiated from: BOOST_STATIC_ASSERT (Point::dimensions == 2); ~~~~~~~^ /Volumes/Data/mike/Downloads/boost_1_43_0/boost/graph/fruchterman_reingold.hpp:417:19: note: in instantiation of template class 'boost::grid_force_pairs<boost::rectangle_topology<boost::random::linear_congruential<int, 48271, 0, 2147483647, 399268537> >, boost::iterator_property_map<__gnu_cxx::__normal_iterator<boost::simple_point<double> *, std::vector<boost::simple_point<double>, std::allocator<boost::simple_point<double> > > >, boost::vec_adj_list_vertex_id_map<boost::property<boost::vertex_name_t, std::basic_string<char>, boost::no_property>, unsigned long>, boost::simple_point<double>, boost::simple_point<double> &> >' requested here make_grid_force_pairs(topology, position, g)), ^ /Volumes/Data/mike/Downloads/boost_1_43_0/boost/graph/fruchterman_reingold.hpp:431:3: note: in instantiation of function template specialization 'boost::fruchterman_reingold_force_directed_layout<boost::rectangle_topology<boost::random::linear_congruential<int, 48271, 0, 2147483647, 399268537> >, boost::adjacency_list<boost::listS, boost::vecS, boost::undirectedS, boost::property<boost::vertex_name_t, std::basic_string<char>, boost::no_property>, boost::no_property, boost::no_property, boost::listS>, boost::iterator_property_map<__gnu_cxx::__normal_iterator<boost::simple_point<double> *, std::vector<boost::simple_point<double>, std::allocator<boost::simple_point<double> > > >, boost::vec_adj_list_vertex_id_map<boost::property<boost::vertex_name_t, std::basic_string<char>, boost::no_property>, unsigned long>, boost::simple_point<double>, boost::simple_point<double> &>, boost::square_distance_attractive_force, boost::attractive_force_t, boost::no_property>' requested here fruchterman_reingold_force_directed_layout ^ test.cpp:48:3: note: in instantiation of function template specialization 'boost::fruchterman_reingold_force_directed_layout<boost::rectangle_topology<boost::random::linear_congruential<int, 48271, 0, 2147483647, 399268537> >, boost::adjacency_list<boost::listS, boost::vecS, boost::undirectedS, boost::property<boost::vertex_name_t, std::basic_string<char>, boost::no_property>, boost::no_property, boost::no_property, boost::listS>, boost::iterator_property_map<__gnu_cxx::__normal_iterator<boost::simple_point<double> *, std::vector<boost::simple_point<double>, std::allocator<boost::simple_point<double> > > >, boost::vec_adj_list_vertex_id_map<boost::property<boost::vertex_name_t, std::basic_string<char>, boost::no_property>, unsigned long>, boost::simple_point<double>, boost::simple_point<double> &> >' requested here fruchterman_reingold_force_directed_layout(g, position, topology); ^ 1 error generated.

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• error LNK2019 for ZLib sample compare.

  - by Nano HE

  Hello. I created win32 console application in vs2010 (without select the option of precompiled header). And I inserted the code below. but *.obj link failed. Could you provide me more information about the error. I searched MSDN, but still can't understand it. #include <stdio.h> #include "zlib.h" // Demonstration of zlib utility functions unsigned long file_size(char *filename) { FILE *pFile = fopen(filename, "rb"); fseek (pFile, 0, SEEK_END); unsigned long size = ftell(pFile); fclose (pFile); return size; } int decompress_one_file(char *infilename, char *outfilename) { gzFile infile = gzopen(infilename, "rb"); FILE *outfile = fopen(outfilename, "wb"); if (!infile || !outfile) return -1; char buffer[128]; int num_read = 0; while ((num_read = gzread(infile, buffer, sizeof(buffer))) > 0) { fwrite(buffer, 1, num_read, outfile); } gzclose(infile); fclose(outfile); } int compress_one_file(char *infilename, char *outfilename) { FILE *infile = fopen(infilename, "rb"); gzFile outfile = gzopen(outfilename, "wb"); if (!infile || !outfile) return -1; char inbuffer[128]; int num_read = 0; unsigned long total_read = 0, total_wrote = 0; while ((num_read = fread(inbuffer, 1, sizeof(inbuffer), infile)) > 0) { total_read += num_read; gzwrite(outfile, inbuffer, num_read); } fclose(infile); gzclose(outfile); printf("Read %ld bytes, Wrote %ld bytes, Compression factor %4.2f%%\n", total_read, file_size(outfilename), (1.0-file_size(outfilename)*1.0/total_read)*100.0); } int main(int argc, char **argv) { compress_one_file(argv[1],argv[2]); decompress_one_file(argv[2],argv[3]);} Output: 1>------ Build started: Project: zlibApp, Configuration: Debug Win32 ------ 1> zlibApp.cpp 1>d:\learning\cpp\cppvs2010\zlibapp\zlibapp\zlibapp.cpp(15): warning C4996: 'fopen': This function or variable may be unsafe. Consider using fopen_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details. 1> c:\program files\microsoft visual studio 10.0\vc\include\stdio.h(234) : see declaration of 'fopen' 1>d:\learning\cpp\cppvs2010\zlibapp\zlibapp\zlibapp.cpp(25): warning C4996: 'fopen': This function or variable may be unsafe. Consider using fopen_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details. 1> c:\program files\microsoft visual studio 10.0\vc\include\stdio.h(234) : see declaration of 'fopen' 1>d:\learning\cpp\cppvs2010\zlibapp\zlibapp\zlibapp.cpp(40): warning C4996: 'fopen': This function or variable may be unsafe. Consider using fopen_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details. 1> c:\program files\microsoft visual studio 10.0\vc\include\stdio.h(234) : see declaration of 'fopen' 1>d:\learning\cpp\cppvs2010\zlibapp\zlibapp\zlibapp.cpp(36): warning C4715: 'decompress_one_file' : not all control paths return a value 1>d:\learning\cpp\cppvs2010\zlibapp\zlibapp\zlibapp.cpp(57): warning C4715: 'compress_one_file' : not all control paths return a value 1>zlibApp.obj : error LNK2019: unresolved external symbol _gzclose referenced in function "int __cdecl decompress_one_file(char *,char *)" (?decompress_one_file@@YAHPAD0@Z) 1>zlibApp.obj : error LNK2019: unresolved external symbol _gzread referenced in function "int __cdecl decompress_one_file(char *,char *)" (?decompress_one_file@@YAHPAD0@Z) 1>zlibApp.obj : error LNK2019: unresolved external symbol _gzopen referenced in function "int __cdecl decompress_one_file(char *,char *)" (?decompress_one_file@@YAHPAD0@Z) 1>zlibApp.obj : error LNK2019: unresolved external symbol _gzwrite referenced in function "int __cdecl compress_one_file(char *,char *)" (?compress_one_file@@YAHPAD0@Z) 1>D:\learning\cpp\cppVS2010\zlibApp\Debug\zlibApp.exe : fatal error LNK1120: 4 unresolved externals ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

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• Struts 2 TypeConversion problem

  - by Parhs

  Hello... i have a big problem... i have this map HashMap<Long, String> examValues; It gets populated by textboxes automatically with name="examValues[id]" Although i explicily defined the element as String , it doesnt care!!! I want everything to be a String... The result is to get a java.lang.ClassCastException: java.lang.Long cannot be cast to java.lang.String when i try to System.out.print(examValues.get(examValue.getExam().getId()).getClass().getName()); INFO: java.lang.ClassCastException: java.lang.Long cannot be cast to java.lang.String at gr.medilab.logic.action.exams.Exams.fill_edit(Exams.java:204) at gr.medilab.logic.action.exams.Exams.fill(Exams.java:95) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:441) at com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:280) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:243) at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:165) at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:252) at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68) at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:122) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195) at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195) at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:179) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) at org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:75) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:94) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:235) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:89) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:130) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) at org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:267) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:126) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:138) at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) at com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:165) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:179) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:176) at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237) at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52) at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:488) at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77) at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:215) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:277) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:188) at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:641) at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:97) at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:85) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:185) at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:332) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:233) at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:165) at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:791) at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:693) at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:954) at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:170) at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:135) at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:102) at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:88) at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:76) at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:53) at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:57) at com.sun.grizzly.ContextTask.run(ContextTask.java:69) at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:330) at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:309) at java.lang.Thread.run(Thread.java:619) Any idea?

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• Is the Cloud ready for an Enterprise Java web application? Seeking a JEE hosting advice.

  - by Jakub Holý

  Greetings to all the smart people around here! I'd like to ask whether it is feasible or a good idea at all to deploy a Java enterprise web application to a Cloud such as Amazon EC2. More exactly, I'm looking for infrastructure options for an application that shall handle few hundred users with long but neither CPU nor memory intensive sessions. I'm considering dedicated servers, virtual private servers (VPSs) and EC2. I've noticed that there is a project called JBoss Cloud so people are working on enabling such a deployment, on the other hand it doesn't seem to be mature yet and I'm not sure that the cloud is ready for this kind of applications, which differs from the typical cloud-based applications like Twitter. Would you recommend to deploy it to the cloud? What are the pros and cons? The application is a Java EE 5 web application whose main function is to enable users to compose their own customized Product by combining the available Parts. It uses stateless and stateful session beans and JPA for persistence of entities to a RDBMS and fetches information about Parts from the company's inventory system via a web service. Aside of external users it's used also by few internal ones, who are authenticated against the company's LDAP. The application should handle around 300-400 concurrent users building their product and should be reasonably scalable and available though these qualities are only of a medium importance at this stage. I've proposed an architecture consisting of a firewall (FW) and load balancer supporting sticky sessions and https (in the Cloud this would be replaced with EC2's Elastic Load Balancing service and FW on the app. servers, in a physical architecture the load-balancer would be a HW), then two physical clustered application servers combined with web servers (so that if one fails, a user doesn't loose his/her long built product) and finally a database server. The DB server would need a slave backup instance that can replace the master instance if it fails. This should provide reasonable availability and fault tolerance and provide good scalability as long as a single RDBMS can keep with the load, which should be OK for quite a while because most of the operations are done in the memory using a stateful bean and only occasionally stored or retrieved from the DB and the amount of data is low too. A problematic part could be the dependency on the remote inventory system webservice but with good caching of its outputs in the application it should be OK too. Unfortunately I've only vague idea of the system resources (memory size, number and speed of CPUs/cores) that such an "average Java EE application" for few hundred users needs. My rough and mostly unfounded estimate based on actual Amazon offerings is that 1.7GB and a single, 2-core "modern CPU" with speed around 2.5GHz (the High-CPU Medium Instance) should be sufficient for any of the two application servers (since we can handle higher load by provisioning more of them). Alternatively I would consider using the Large instance (64b, 7.5GB RAM, 2 cores at 1GHz) So my question is whether such a deployment to the cloud is technically and financially feasible or whether dedicated/VPS servers would be a better option and whether there are some real-world experiences with something similar. Thank you very much! /Jakub Holy PS: I've found the JBoss EAP in a Cloud Case Study that shows that it is possible to deploy a real-world Java EE application to the EC2 cloud but unfortunately there're no details regarding topology, instance types, or anything :-(

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• NSMutableString leaks on append or replaceOccurrencesOfString

  - by John

  Hello Folks, I know similar questions have been asked time and time again but I ask that you please bear with me as I cannot seem to find an answer that helps. My application has leaks that are driving me out of my mind. Actually, they are not reported as leaks using Leaks, but my net bytes in ObjectAlloc goes up and up and up and never stops, eventually leading to a crash if it goes on long enough (not very long). The problem occurs with NSMutableStrings. I think there is either something fundamental I don't understand about them, or I am facing another problem that I am having difficulty tracking down but keeps hiding behind the NSMutableStrings. Specifically, I am noticing that whenever I append to or perform a replace on a NSMutableString, ObjectAlloc reports what appear to be mismatches in malloc/frees behind the scene when resizing the NSMutableString. I'm sorry to say this is the second time I'm facing this problem - the first time I messed around for hours and hours and finally the problem went away (magic!) but I don't really know why. When I look at the code below (and believe me, I've stared at it for hours) I cannot see the problem. I look at the code and think to myself that I should be fine because I'm releasing the only object for which I am responsible (aString) and that NSMutableString should be taking care of cleaning up after any resizing it does. In the second example, just so you know in case it helps, the string being passed in comes from an ASIHTTPRequest object (it's the responseString) and I don't do anything at all with it. It's being called simply like so ([self DoStuff2:[request responseString]]) and I don't free the request myself either (I'm using a ASINetworkQueue and I assume that the requests are destroyed for me (I tried and caused errors because the request was already being release somewhere else). Also, I know it shouldn't do anything, but I even tried wrapping the code in autorelease pools, which of course did nothing. I should mention that this code is being run inside of an NSOperation. I thought that perhaps I am experiencing problems because NSOperations should create an autorelease pool for themselves, but I've tried that to no avail. Not related to NSMutableString, but I find I also have similar problems using the NSString componentsSeparatedByString method. Sometimes the memory used by the array that gets the separated components is never released. Hmmm...strings in general seem to be somewhat problematic for me it seems. I would appreciate ANY help anyone can provide. If you require more info, I'll be glad to add it. I do promise you that I've struggled with this (and other problems) for weeks and every problem I encounter I research hard and long until I find a solution - this is not an idle request, but a true cry for help! I've written so much code and now I'm trying to seal some small leaks etc and I notice this problem. Honestly, I cannot believe how memory management in Objective C can stump me so at times...I've read Apple's memory mgmt docs many times and I thought I thoroughly understood it and I try to be diligent about releasing objects I own, but sometimes I find myself wondering if I truly understand...I would like to put this to bed once and make sure I understand all this fully - to have this sort of question/problem after writing thousands of lines of code is more than a little scary/embarrassing/annoying. So again, if anybody has any insight, I'd be grateful. Thanks for your time and efforts. -(void)DoStuff { NSString *aString [ [[NSString alloc] initWithFormat:@"text %@ more text", self.strVariable]; [self.someMutableStringVar replaceOccurrencesOfString:@"replace" withString:aString options:NSCaseInsensitiveSearch range:NSMakeRange(0, [self.someMutableStringVar length])]; [aString release]; } -(void)DoStuff2:(NSString *)aString { [self.someMutableStringVar appendString:aString]; }

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• Managing highly repetitive code and documentation in Java

  - by polygenelubricants

  Highly repetitive code is generally a bad thing, and there are design patterns that can help minimize this. However, sometimes it's simply inevitable due to the constraints of the language itself. Take the following example from java.util.Arrays: /** * Assigns the specified long value to each element of the specified * range of the specified array of longs. The range to be filled * extends from index <tt>fromIndex</tt>, inclusive, to index * <tt>toIndex</tt>, exclusive. (If <tt>fromIndex==toIndex</tt>, the * range to be filled is empty.) * * @param a the array to be filled * @param fromIndex the index of the first element (inclusive) to be * filled with the specified value * @param toIndex the index of the last element (exclusive) to be * filled with the specified value * @param val the value to be stored in all elements of the array * @throws IllegalArgumentException if <tt>fromIndex &gt; toIndex</tt> * @throws ArrayIndexOutOfBoundsException if <tt>fromIndex &lt; 0</tt> or * <tt>toIndex &gt; a.length</tt> */ public static void fill(long[] a, int fromIndex, int toIndex, long val) { rangeCheck(a.length, fromIndex, toIndex); for (int i=fromIndex; i<toIndex; i++) a[i] = val; } The above snippet appears in the source code 8 times, with very little variation in the documentation/method signature but exactly the same method body, one for each of the root array types int[], short[], char[], byte[], boolean[], double[], float[], and Object[]. I believe that unless one resorts to reflection (which is an entirely different subject in itself), this repetition is inevitable. I understand that as a utility class, such high concentration of repetitive Java code is highly atypical, but even with the best practice, repetition does happen! Refactoring doesn't always work because it's not always possible (the obvious case is when the repetition is in the documentation). Obviously maintaining this source code is a nightmare. A slight typo in the documentation, or a minor bug in the implementation, is multiplied by however many repetitions was made. In fact, the best example happens to involve this exact class: Google Research Blog - Extra, Extra - Read All About It: Nearly All Binary Searches and Mergesorts are Broken (by Joshua Bloch, Software Engineer) The bug is a surprisingly subtle one, occurring in what many thought to be just a simple and straightforward algorithm. // int mid =(low + high) / 2; // the bug int mid = (low + high) >>> 1; // the fix The above line appears 11 times in the source code! So my questions are: How are these kinds of repetitive Java code/documentation handled in practice? How are they developed, maintained, and tested? Do you start with "the original", and make it as mature as possible, and then copy and paste as necessary and hope you didn't make a mistake? And if you did make a mistake in the original, then just fix it everywhere, unless you're comfortable with deleting the copies and repeating the whole replication process? And you apply this same process for the testing code as well? Would Java benefit from some sort of limited-use source code preprocessing for this kind of thing? Perhaps Sun has their own preprocessor to help write, maintain, document and test these kind of repetitive library code? A comment requested another example, so I pulled this one from Google Collections: com.google.common.base.Predicates lines 276-310 (AndPredicate) vs lines 312-346 (OrPredicate). The source for these two classes are identical, except for: AndPredicate vs OrPredicate (each appears 5 times in its class) "And(" vs Or(" (in the respective toString() methods) #and vs #or (in the @see Javadoc comments) true vs false (in apply; ! can be rewritten out of the expression) -1 /* all bits on */ vs 0 /* all bits off */ in hashCode() &= vs |= in hashCode()

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• How to do inclusive range queries when only half-open range is supported (ala SortedMap.subMap)

  - by polygenelubricants

  On SortedMap.subMap This is the API for SortedMap<K,V>.subMap: SortedMap<K,V> subMap(K fromKey, K toKey) : Returns a view of the portion of this map whose keys range from fromKey, inclusive, to toKey, exclusive. This inclusive lower bound, exclusive upper bound combo ("half-open range") is something that is prevalent in Java, and while it does have its benefits, it also has its quirks, as we shall soon see. The following snippet illustrates a simple usage of subMap: static <K,V> SortedMap<K,V> someSortOfSortedMap() { return Collections.synchronizedSortedMap(new TreeMap<K,V>()); } //... SortedMap<Integer,String> map = someSortOfSortedMap(); map.put(1, "One"); map.put(3, "Three"); map.put(5, "Five"); map.put(7, "Seven"); map.put(9, "Nine"); System.out.println(map.subMap(0, 4)); // prints "{1=One, 3=Three}" System.out.println(map.subMap(3, 7)); // prints "{3=Three, 5=Five}" The last line is important: 7=Seven is excluded, due to the exclusive upper bound nature of subMap. Now suppose that we actually need an inclusive upper bound, then we could try to write a utility method like this: static <V> SortedMap<Integer,V> subMapInclusive(SortedMap<Integer,V> map, int from, int to) { return (to == Integer.MAX_VALUE) ? map.tailMap(from) : map.subMap(from, to + 1); } Then, continuing on with the above snippet, we get: System.out.println(subMapInclusive(map, 3, 7)); // prints "{3=Three, 5=Five, 7=Seven}" map.put(Integer.MAX_VALUE, "Infinity"); System.out.println(subMapInclusive(map, 5, Integer.MAX_VALUE)); // {5=Five, 7=Seven, 9=Nine, 2147483647=Infinity} A couple of key observations need to be made: The good news is that we don't care about the type of the values, but... subMapInclusive assumes Integer keys for to + 1 to work. A generic version that also takes e.g. Long keys is not possible (see related questions) Not to mention that for Long, we need to compare against Long.MAX_VALUE instead Overloads for the numeric primitive boxed types Byte, Character, etc, as keys, must all be written individually A special check need to be made for toInclusive == Integer.MAX_VALUE, because +1 would overflow, and subMap would throw IllegalArgumentException: fromKey > toKey This, generally speaking, is an overly ugly and overly specific solution What about String keys? Or some unknown type that may not even be Comparable<?>? So the question is: is it possible to write a general subMapInclusive method that takes a SortedMap<K,V>, and K fromKey, K toKey, and perform an inclusive-range subMap queries? Related questions Are upper bounds of indexed ranges always assumed to be exclusive? Is it possible to write a generic +1 method for numeric box types in Java? On NavigableMap It should be mentioned that there's a NavigableMap.subMap overload that takes two additional boolean variables to signify whether the bounds are inclusive or exclusive. Had this been made available in SortedMap, then none of the above would've even been asked. So working with a NavigableMap<K,V> for inclusive range queries would've been ideal, but while Collections provides utility methods for SortedMap (among other things), we aren't afforded the same luxury with NavigableMap. Related questions Writing a synchronized thread-safety wrapper for NavigableMap On API providing only exclusive upper bound range queries Does this highlight a problem with exclusive upper bound range queries? How were inclusive range queries done in the past when exclusive upper bound is the only available functionality?

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