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  • Detecting walls or floors in pygame

    - by Serial
    I am trying to make bullets bounce of walls, but I can't figure out how to correctly do the collision detection. What I am currently doing is iterating through all the solid blocks and if the bullet hits the bottom, top or sides, its vector is adjusted accordingly. However, sometimes when I shoot, the bullet doesn't bounce, I think it's when I shoot at a border between two blocks. Here is the update method for my Bullet class: def update(self, dt): if self.can_bounce: #if the bullet hasnt bounced find its vector using the mousclick pos and player pos speed = -10. range = 200 distance = [self.mouse_x - self.player[0], self.mouse_y - self.player[1]] norm = math.sqrt(distance[0] ** 2 + distance[1] ** 2) direction = [distance[0] / norm, distance[1 ] / norm] bullet_vector = [direction[0] * speed, direction[1] * speed] self.dx = bullet_vector[0] self.dy = bullet_vector[1] #check each block for collision for block in self.game.solid_blocks: last = self.rect.copy() if self.rect.colliderect(block): topcheck = self.rect.top < block.rect.bottom and self.rect.top > block.rect.top bottomcheck = self.rect.bottom > block.rect.top and self.rect.bottom < block.rect.bottom rightcheck = self.rect.right > block.rect.left and self.rect.right < block.rect.right leftcheck = self.rect.left < block.rect.right and self.rect.left > block.rect.left each test tests if it hit the top bottom left or right side of the block its colliding with if self.can_bounce: if topcheck: self.rect = last self.dy *= -1 self.can_bounce = False print "top" if bottomcheck: self.rect = last self.dy *= -1 #Bottom check self.can_bounce = False print "bottom" if rightcheck: self.rect = last self.dx *= -1 #right check self.can_bounce = False print "right" if leftcheck: self.rect = last self.dx *= -1 #left check self.can_bounce = False print "left" else: # if it has already bounced and colliding again kill it self.kill() for enemy in self.game.enemies_list: if self.rect.colliderect(enemy): self.kill() #update position self.rect.x -= self.dx self.rect.y -= self.dy This definitely isn't the best way to do it but I can't think of another way. If anyone has done this or can help that would be awesome!

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  • Opinion : quel avenir pour Firefox ? Le design et la communication l'ont-ils emporté sur les problématiques techniques ?

    Opinion : quel avenir pour Firefox ? Le design et la communication l'ont-ils emporté sur les problématiques techniques ? Historiquement connu comme un grand projet open source, dont la communauté a été secouée à plusieurs reprises (donnant naissance à quelques forks, dont Iceweasel), Firefox fait désormais la une comme un des grands acteurs de la navigation Web. Et ce n'est pas volé ! Outre les problématiques de sécurité, desquelles il s'est occupé très tôt, les innovations y ont été légion et nul doute que les navigateurs ne seraient pas ce qu'ils sont aujourd'hui sans cet acteur légendaire. Pourtant, depuis la version 3, une frénésie de sorties m'appelle à me poser de vraies questions s...

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  • OSI Model

    - by kaleidoscope
    The Open System Interconnection Reference Model (OSI Reference Model or OSI Model) is an abstract description for layered communications and computer network protocol design. In its most basic form, it divides network architecture into seven layers which, from top to bottom, are the Application, Presentation, Session, Transport, Network, Data Link, and Physical Layers. It is therefore often referred to as the OSI Seven Layer Model. A layer is a collection of conceptually similar functions that provide services to the layer above it and receives service from the layer below it. Description of OSI layers: Layer 1: Physical Layer ·         Defines the electrical and physical specifications for devices. In particular, it defines the relationship between a device and a physical medium. ·         Establishment and termination of a connection to a communications medium. ·         Participation in the process whereby the communication resources are effectively shared among multiple users. ·         Modulation or conversion between the representation of digital data in user equipment and the corresponding signals transmitted over a communications channel. Layer 2: Data Link Layer ·         Provides the functional and procedural means to transfer data between network entities. ·         Detect and possibly correct errors that may occur in the Physical Layer. The error check is performed using Frame Check Sequence (FCS). ·         Addresses is then sought to see if it needs to process the rest of the frame itself or whether to pass it on to another host. ·         The Layer is divided into two sub layers: The Media Access Control (MAC) layer and the Logical Link Control (LLC) layer. ·         MAC sub layer controls how a computer on the network gains access to the data and permission to transmit it. ·         LLC layer controls frame synchronization, flow control and error checking.   Layer 3: Network Layer ·         Provides the functional and procedural means of transferring variable length data sequences from a source to a destination via one or more networks. ·         Performs network routing functions, and might also perform fragmentation and reassembly, and report delivery errors. ·         Network Layer Routers operate at this layer—sending data throughout the extended network and making the Internet possible.   Layer 4: Transport Layer ·         Provides transparent transfer of data between end users, providing reliable data transfer services to the upper layers. ·         Controls the reliability of a given link through flow control, segmentation/de-segmentation, and error control. ·         Transport Layer can keep track of the segments and retransmit those that fail. Layer 5: Session Layer ·         Controls the dialogues (connections) between computers. ·         Establishes, manages and terminates the connections between the local and remote application. ·         Provides for full-duplex, half-duplex, or simplex operation, and establishes checkpointing, adjournment, termination, and restart procedures. ·         Implemented explicitly in application environments that use remote procedure calls. Layer 6: Presentation Layer ·         Establishes a context between Application Layer entities, in which the higher-layer entities can use different syntax and semantics, as long as the presentation service understands both and the mapping between them. The presentation service data units are then encapsulated into Session Protocol data units, and moved down the stack. ·         Provides independence from differences in data representation (e.g., encryption) by translating from application to network format, and vice versa. The presentation layer works to transform data into the form that the application layer can accept. This layer formats and encrypts data to be sent across a network, providing freedom from compatibility problems. It is sometimes called the syntax layer. Layer 7: Application Layer ·         This layer interacts with software applications that implement a communicating component. ·         Identifies communication partners, determines resource availability, and synchronizes communication. o       When identifying communication partners, the application layer determines the identity and availability of communication partners for an application with data to transmit. o       When determining resource availability, the application layer must decide whether sufficient network or the requested communication exists. o       In synchronizing communication, all communication between applications requires cooperation that is managed by the application layer. Technorati Tags: Kunal,OSI,Networking

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  • Using thread inter-communication to increase my server app's IO throughput; not sure how

    - by Howard Guo
    My server application creates a new thread for each incoming connection. Incoming requests are serialized in a BlockingQueue. There is one worker thread taking items from the queue, produce a response and send the response through socket. I have noticed a throughput issue: Currently, worker thread is responsible of sending the response message through socket, thus severely wasting processing power and throughput. I am considering: rather than sending the response itself, why not telling network IO threads to send the response? However, when I think about thread inter-communication, I cannot yet figure out how to approach it: Worker thread will produce a response, but how will it inform the response message to IO thread? Is there a standard/best practice? Thank you.

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  • Android - Good alternatives to XMPP or REST for communication between servers and clients?

    - by Ann
    Hello I am doing a project. For my project i need to create an Android application. I will use Java and Eclipse. The main idea of app. The application works on environment/location. Example the application needs to pick up on the users location. He should then also be able to communicate with his friends or colleagues which are in the same location. My question: I am looking for a good alternatives to XMPP or REST for communication between servers and clients? Any advice. Kind regards

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  • How to find keycodes for Fn + keys?

    - by budwiser
    I'm trying to find out the keycode for Fn+? keypress (left arrow). Xev outputs FocusOut event, serial 36, synthetic NO, window 0x3c00001,    mode NotifyGrab, detail NotifyAncestor FocusIn event, serial 36, synthetic NO, window 0x3c00001,    mode NotifyUngrab, detail NotifyAncestor KeymapNotify event, serial 36, synthetic NO, window 0x0,    keys:  4294967213 0   0   0   0   0   0   0   0   0   0   0   0   0   0   0              0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   If it is telling me the keycode here, I'm not able to interpret it so help would be appreciated. I'm also curious for finding out if it's possible to bind something to Fn+Del but when trying out this combination, Xev outputs KeyPress event, serial 36, synthetic NO, window 0x3c00001, root 0xad, subw 0x0, time 1984903, (-666,480), root:(53,533), state 0x0, keycode 119 (keysym 0xffff, Delete), same_screen YES, XLookupString gives 1 bytes: (7f) " " XmbLookupString gives 1 bytes: (7f) " " XFilterEvent returns: False KeyRelease event, serial 36, synthetic NO, window 0x3c00001, root 0xad, subw 0x0, time 1985008, (-666,480), root:(53,533), state 0x0, keycode 119 (keysym 0xffff, Delete), same_screen YES, XLookupString gives 1 bytes: (7f) " " XFilterEvent returns: False which is exactly the same as pressing del without Fn. So, summary for short How can I find keycode for Fn+? (left arrow)? Is it even possible to bind something to Fn+Del or am I facing windmills here?

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  • Keyboard / keymap problems with Xubuntu 12.04 + NX nomachine

    - by bajafresh4life
    I'm running NX client on my Macbook Pro to connect to a Xubuntu 12.04 desktop at work. I have configured NX client to start up a console upon connection. I am able to connect to my remote linux machine and I get a simple xterm console. However, when I run xfce4-session, half my keys no longer work. For example, when I launch a terminal, I typing a, s, or d works, but if type w, e, r, or t, the cursor just blinks. If I ctrl-C out of xfce4-session, all the keys work fine in my xterm console. If I run xev, this is the output for when I hit a key that works: KeyRelease event, serial 34, synthetic NO, window 0x2e00001, root 0x373, subw 0x0, time 170160781, (-45,-21), root:(824,429), state 0x4, keycode 16 (keysym 0x63, c), same_screen YES, XLookupString gives 1 bytes: (03) "" XFilterEvent returns: False KeyRelease event, serial 34, synthetic NO, window 0x2e00001, root 0x373, subw 0x0, time 170160781, (-45,-21), root:(824,429), state 0x4, keycode 67 (keysym 0xffe3, Control_L), same_screen YES, XKeysymToKeycode returns keycode: 63 XLookupString gives 0 bytes: XFilterEvent returns: False but when I hit a key that doesn't work: FocusOut event, serial 34, synthetic NO, window 0x2e00001, mode NotifyGrab, detail NotifyAncestor FocusIn event, serial 34, synthetic NO, window 0x2e00001, mode NotifyUngrab, detail NotifyAncestor KeymapNotify event, serial 34, synthetic NO, window 0x0, keys: 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Any ideas on what I can do to troubleshoot this issue? Googling around offered a few suggestions (like playing with xmodmap) but nothing seemed to work. Also, one thing worth mentioning is that I do not have any keyboard issues when remoting into a different Ubuntu 10 box via NX.

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  • How to find keycodes for Fn + keys in Ubuntu 11.10

    - by budwiser
    I'm trying to find out the keycode for Fn+? keypress (left arrow). Xev outputs FocusOut event, serial 36, synthetic NO, window 0x3c00001,    mode NotifyGrab, detail NotifyAncestor FocusIn event, serial 36, synthetic NO, window 0x3c00001,    mode NotifyUngrab, detail NotifyAncestor KeymapNotify event, serial 36, synthetic NO, window 0x0,    keys:  4294967213 0   0   0   0   0   0   0   0   0   0   0   0   0   0   0              0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   If it is telling me the keycode here, I'm not able to interpret it so help would be appreciated. I'm also curious for finding out if it's possible to bind something to Fn+Del but when trying out this combination, Xev outputs KeyPress event, serial 36, synthetic NO, window 0x3c00001, root 0xad, subw 0x0, time 1984903, (-666,480), root:(53,533), state 0x0, keycode 119 (keysym 0xffff, Delete), same_screen YES, XLookupString gives 1 bytes: (7f) " " XmbLookupString gives 1 bytes: (7f) " " XFilterEvent returns: False KeyRelease event, serial 36, synthetic NO, window 0x3c00001, root 0xad, subw 0x0, time 1985008, (-666,480), root:(53,533), state 0x0, keycode 119 (keysym 0xffff, Delete), same_screen YES, XLookupString gives 1 bytes: (7f) " " XFilterEvent returns: False which is exactly the same as pressing del without Fn. So, summary for short How can I find keycode for Fn+? (left arrow)? Is it even possible to bind something to Fn+Del or am I facing windmills here?

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  • Fixing Two keys events on single key press by xmodmap

    - by William.Ebe
    I'm using Dell Latitude D620. Whenever, I'm pressing the space key, the down arrow key also triggered perform it's action. Here is the log: KeyPress event, serial 30, synthetic NO, window 0x3200001, root 0x10c, subw 0x0, time 2248017, (70,-9), root:(76,39), state 0x0, keycode 116 (keysym 0xff54, Down), same_screen YES, XLookupString gives 0 bytes: XmbLookupString gives 0 bytes: XFilterEvent returns: False KeyPress event, serial 31, synthetic NO, window 0x3200001, root 0x10c, subw 0x0, time 2248018, (70,-9), root:(76,39), state 0x0, keycode 65 (keysym 0x20, space), same_screen YES, XLookupString gives 1 bytes: (20) " " XmbLookupString gives 1 bytes: (20) " " XFilterEvent returns: False KeyRelease event, serial 33, synthetic NO, window 0x3200001, root 0x10c, subw 0x0, time 2248083, (70,-9), root:(76,39), state 0x0, keycode 65 (keysym 0x20, space), same_screen YES, XLookupString gives 1 bytes: (20) " " XFilterEvent returns: False KeyRelease event, serial 33, synthetic NO, window 0x3200001, root 0x10c, subw 0x0, time 2248085, (70,-9), root:(76,39), state 0x0, keycode 116 (keysym 0xff54, Down), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False ClientMessage event, serial 33, synthetic YES, window 0x3200001, message_type 0x157 (WM_PROTOCOLS), format 32, message 0x155 (WM_DELETE_WINDOW) The above log is for a single press+release of spacebar key. I would like to know how to fix that. Thanks. PS: I'm using the same laptop to post question. If somebody helps to align it into code format, it would be helpful as I can't do that with this keyboard properly.

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  • Re-downloading Microsoft SQL Server 2008 Standard because of license issues?

    - by James Watt
    I have many clients who have purchased Microsoft SQL Server 2008 Standard. Unlike other Microsoft software, there is not a serial number provided for each customer to install the software. Futhermore, Microsoft's TechNet website lists this information about SQL Server instead of providing a key: "This product is pre-pidded." This means that the configuration file for SQL server contains your serial number instead of manually entering it. My question is then: does this serial change for each customer? The reason I ask: I'd rather not download a 3.2GB disc image over and over again for each of my customers individually. But, I don't want to risk using the same image over and over again resulting in Microsoft banning the serial for over use (as opposed to each customer using their copy with THEIR serial number.) Thanks in advance.

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  • How do I read text from a serial port?

    - by user2164
    I am trying to read data off of a Windows serial port through Java. I have the javax.comm libraries and am able to get some data but not correct data. When I read the port into a byte array and convert it to text I get a series of characters but no real text string. I have tried to specify the byte array as being both "UTF-8" and "US-ASCII". Does anyone know how to get real text out of this? Here is my code: while (inputStream.available() > 0) { int numBytes = inputStream.read(readBuffer); System.out.println("Reading from " + portId.getName() + ": "); System.out.println("Read " + numBytes + " bytes"); } System.out.println(new String(readBuffer)); System.out.println(new String(readBuffer, "UTF-8")); System.out.println(new String(readBuffer, "US-ASCII")); the output of the first three lines will not let me copy and paste (I assume because they are not normal characters). Here is the output of the Hex: 78786000e67e9e60061e8606781e66e0869e98e086f89898861878809e1e9880 I am reading from a Hollux GPS device which does output in string format. I know this for sure because I did it through C#. The settings that I am using for communication which I know are right from the work in the C# app are: Baud Rate: 9600 Databits: 8 Stop bit: 1 parity: none

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  • wpf progress bar slows 10x times serial port communications... how could be possible that?

    - by D_Guidi
    I know that this could look a dumb question, but here's my problem. I have a worker dialog that "hides" a backgroundworker, so in a worker thread I do my job, I report the progress in a standard way and then I show the results in my WPF program. The dialog contains a simply animated gif and a standard wpf progress bar, and when a progress is notified I set Value property. All lokks as usual and works well for any kind of job, like web service calls, db queries, background elaboration and so on. For my job we use also many "couplers", card readers that reads data from smart card, that are managed with native C code that access to serial port (so, I don't use .NET SerialPort object). I have some nunit tests and I read a sample card in 10 seconds, but using my actual program, under the backgroundworker and showing my worker dialog, I need 1.30 minutes to do the SAME job. I struggled into problem for days until I decide to remove the worker dialog, and without dialog I obtain the same performances of the tests! So I investigated, and It's not the dialog, not the animated gif, but the wpf progress bar! Simply the fact that a progress bar is shown (so, no animation, no Value set called, nothing of nothing) slows serialport communicatitons. Looks incredible? I've tested this behavior and it's exactly what happens.

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  • How to establish the real-time communication between Shopping cart running MySQL and Internal System Running PostgreSQL [closed]

    - by Andrew
    I am thinking about the way of establishing some-sort of real-time connection between MySQLpowered shopping cart and internal system that is running on PostgreSQL. Could you give me some sort of insight on this topic? For example, I can write some sort of csv export application, then enable remote MySQL for over the internet connection and then import csv to mysql directly from PC. Or upload csv and run cron on server. But this way of import-export causing delays; so I would like to link databased (or some msort). I have never done it before and would like to hear some opinions about this. Another way "just a thought" might to implement triggers that would initiate the update process via csv; but again, I would like to avoid csv. Do you have any good advise? Maybe some specific examples?

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  • Do I need a VPN to secure communication over a T1 line?

    - by Seth
    I have a dedicated T1 line that runs between my office and my data center. Both ends have public IP addresses. On both ends, we have a T1 routers which connect to SonicWall firewalls. The SonicWalls do a site-to-site VPN and handle the network translation, so the computers on the office network (10.0.100.x) can access the servers in the rack (10.0.103.x). So the question: can I just add a static route to the SonicWalls so each network can access each other with out the VPN? Are there security problems (such as, someone else adding the appropriate static route and being able to access either the office or the datacenter)? Is there another / better way to do it? The reason I'm looking at this is because the T1 is already a pretty small pipe, and having the VPN overhead makes connectivity really slow.

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  • Why Would one VLAN have no Communication on one Switch?

    - by Webs
    So the problem is we have a device or host that needs to communicate on a specific VLAN. This VLAN is not new, it is running all throughout our environment and works fine. But the VLAN was recently configured on the switch in question, a Cisco 3750. The DHCP server is handing out addresses on that VLAN with no problem. I have verified the cable between the host and switch and tried multiple hosts, but none of them can communicate or get an address. I plugged my laptop into an empty port which had a different VLAN assigned and immediately got a DHCP address. When I changed that port to the same VLAN I'm having issues with I got the same problem. The laptop just sits there and tries to DHCP an address but nothing happens. I double checked the cores and their Layer 3 VLAN config and its fine too. Plus I figured the issue couldn't be with them because the VLAN works fine everywhere else it exists. So the only other thing I can think of is the switch, but the VLAN exists on the switch and seems to be configured correctly. The trunks appear to be configured just fine as well too. Anyone have any ideas? I'm lost on this one.

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  • HTTPS vs. VPN for communication between business partners?

    - by Andrew H
    A business partner has asked to set up a site-to-site VPN just so that a few servers can communicate with each other over HTTPS. I'm convinced this isn't necessary, or even desirable. To be fair it must be part of a wider policy, potentially even a legal requirement. However I'd like to convince them to simply offer an IP to us (and us only) and a port of their choosing for HTTPS. Has anyone had a similar experience, or had to come up with a cast-iron argument against a VPN? Allow me to expand a little - we have a web service that initiates a connection to the partner's corresponding service using an encrypted HTTP connection. The connection uses a client certificate to authenticate. The connection is firewalled so only our IPs can contact the service. So why is a VPN necessary?

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  • Safely transfer files from pc with internet connection to lan without allowing any other form of communication

    - by Hugh Quenneville
    In the company that I work there are computers that are connected to the Internet and computers that are connected to a Local Area Network. The LAN is considered a "safe zone" and the files that reside there should never be copied/moved to a computer that has Internet Access. So, now, if we want to download an installer for an application for example, we download it in a pc that has Internet Access and then move it using a "secure USB stick" to the Local Area Network. Is there a way to create an "safe, one-way connection" between a computer with Internet access and a computer from the LAN? This practically means that only files from the computer with the Internet access can be copied/moved to the LAN. In addition to that, if you want to transfer files you would have to provide your security credentials for the network (so, that only users with the appropriate access levels will be able to transfer files). Is it possible to create something like that and make it completely safe (or at least "equally safe" with the USB method that we currently use) or the fact that the computer with Internet access is connected with a wire to the LAN is a security risk by itself? NOTE: the LAN setup involves 2 Windows 2003 servers with Active Directory, Web servers and pretty much all the services that you would expect to find in a Windows network.

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  • Getting size of a specific byte array from an array of pointers to bytes

    - by Pat James
    In the following example c code, used in an Arduino project, I am looking for the ability to get the size of a specific byte array within an array of pointers to bytes, for example void setup() { Serial.begin(9600); // for debugging byte zero[] = {8, 169, 8, 128, 2,171,145,155,141,177,187,187,2,152,2,8,134,199}; byte one[] = {8, 179, 138, 138, 177 ,2,146, 8, 134, 8, 194,2,1,14,199,7, 145, 8,131, 8,158,8,187,187,191}; byte two[] = {29,7,1,8, 169, 8, 128, 2,171,145,155,141,177,187,187,2,152,2,8,134,199, 2, 2, 8, 179, 138, 138, 177 ,2,146, 8, 134, 8, 194,2,1,14,199,7, 145, 8,131, 8,158,8,187,187,191}; byte* numbers[3] = {zero, one, two }; function(numbers[1], sizeof(numbers[1])/sizeof(byte)); //doesn't work as desired, always passes 2 as the length function(numbers[1], 25); //this works } void loop() { } void function( byte arr[], int len ) { Serial.print("length: "); Serial.println(len); for (int i=0; i<len; i++){ Serial.print("array element "); Serial.print(i); Serial.print(" has value "); Serial.println((int)arr[i]); } } In this code, I understand that sizeof(numbers1)/sizeof(byte)) doesn't work because numbers1 is a pointer and not the byte array value. Is there a way in this example that I can, at runtime, get at the length of a specific (runtime-determined) byte array within an array of pointers to bytes? Understand that I am limited to developing in c (or assembly) for an Arduino environment. Also open to other suggestions rather than the array of pointers to bytes. The overall objective is to organize lists of bytes which can be retrieved, with length, at runtime.

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  • Client Server communication in Java - which approach to use?

    - by markovuksanovic
    I have a typical client server communication - Client sends data to the server, server processes that, and returns data to the client. The problem is that the process operation can take quite some time - order of magnitude - minutes. There are a few approaches that could be used to solve this. Establish a connection, and keep it alive, until the operation is finished and the client receives the response. Establish connection, send data, close the connection. Now the processing takes place and once it is finished the server could establish a connection to the client to send the data. Establish a connection, send data, close the connection. Processing takes place. client asks server, every n minutes/seconds if the operation is finished. If the processing is finished the client fetches the data. I was wondering which approach would be the best way to use. Is there maybe some "de facto" standard for solving this problem? How "expensive" is opening a socket in Java? Solution 1. seems pretty nasty to me, but 2. and 3. could do. The problem with solution 2. is that the server needs to know on which port the client is listening, while solution 3. adds some network overhead.

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  • How NumLock is used in Ubuntu?

    - by ???
    I found that, when the NumLock is on, then many key combination won't work. For example, generally Ctrl-A is used to select all, but it won't work when NumLock is on. There are two keyboard: The laptop one (Thinkpad T61), and an external USB keyboard. The logs shown in xev: (no log when pressed Fn+NumLock on the laptop keyboard) Logs when pressed the NumLock on the USB keyboard: (Switch On) KeyPress event, serial 40, synthetic NO, window 0xb600001, root 0xac, subw 0x0, time 22187595, (102,107), root:(1198,133), state 0x10, keycode 77 (keysym 0xff7f, Num_Lock), same_screen YES, XLookupString gives 0 bytes: XmbLookupString gives 0 bytes: XFilterEvent returns: False PropertyNotify event, serial 40, synthetic NO, window 0xb600001, atom 0x1b8 (XKLAVIER_STATE), time 22187601, state PropertyNewValue KeyRelease event, serial 40, synthetic NO, window 0xb600001, root 0xac, subw 0x0, time 22187723, (102,107), root:(1198,133), state 0x10, keycode 77 (keysym 0xff7f, Num_Lock), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False (Switch Off) KeyPress event, serial 40, synthetic NO, window 0xb600001, root 0xac, subw 0x0, time 22187899, (102,107), root:(1198,133), state 0x0, keycode 77 (keysym 0xff7f, Num_Lock), same_screen YES, XLookupString gives 0 bytes: XmbLookupString gives 0 bytes: XFilterEvent returns: False PropertyNotify event, serial 40, synthetic NO, window 0xb600001, atom 0x1b8 (XKLAVIER_STATE), time 22187904, state PropertyNewValue KeyRelease event, serial 40, synthetic NO, window 0xb600001, root 0xac, subw 0x0, time 22188003, (102,107), root:(1198,133), state 0x10, keycode 77 (keysym 0xff7f, Num_Lock), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False

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  • What's the best Communication Pattern for EJB3-based applications?

    - by Hank
    I'm starting a JEE project that needs to be strongly scalable. So far, the concept was: several Message Driven Beans, responsible for different parts of the architecture each MDB has a Session Bean injected, handling the business logic a couple of Entity Beans, providing access to the persistence layer communication between the different parts of the architecture via Request/Reply concept via JMS messages: MDB receives msg containing activity request uses its session bean to execute necessary business logic returns response object in msg to original requester The idea was that by de-coupling parts of the architecture from each other via the message bus, there is no limit to the scalability. Simply start more components - as long as they are connected to the same bus, we can grow and grow. Unfortunately, we're having massive problems with the request-reply concept. Transaction Mgmt seems to be in our way plenty. It seams that session beans are not supposed to consume messages?! Reading http://blogs.sun.com/fkieviet/entry/request_reply_from_an_ejb and http://forums.sun.com/message.jspa?messageID=10338789, I get the feeling that people actually recommend against the request/reply concept for EJBs. If that is the case, how do you communicate between your EJBs? (Remember, scalability is what I'm after) Details of my current setup: MDB 1 'TestController', uses (local) SLSB 1 'TestService' for business logic TestController.onMessage() makes TestService send a message to queue XYZ and requests a reply TestService uses Bean Managed Transactions TestService establishes a connection & session to the JMS broker via a joint connection factory upon initialization (@PostConstruct) TestService commits the transaction after sending, then begins another transaction and waits 10 sec for the response Message gets to MDB 2 'LocationController', which uses (local) SLSB 2 'LocationService' for business logic LocationController.onMessage() makes LocationService send a message back to the requested JMSReplyTo queue Same BMT concept, same @PostConstruct concept all use the same connection factory to access the broker Problem: The first message gets send (by SLSB 1) and received (by MDB 2) ok. The sending of the returning message (by SLSB 2) is fine as well. However, SLSB 1 never receives anything - it just times out. I tried without the messageSelector, no change, still no receiving message. Is it not ok to consume message by a session bean? SLSB 1 - TestService.java @Resource(name = "jms/mvs.MVSControllerFactory") private javax.jms.ConnectionFactory connectionFactory; @PostConstruct public void initialize() { try { jmsConnection = connectionFactory.createConnection(); session = jmsConnection.createSession(false, Session.AUTO_ACKNOWLEDGE); System.out.println("Connection to JMS Provider established"); } catch (Exception e) { } } public Serializable sendMessageWithResponse(Destination reqDest, Destination respDest, Serializable request) { Serializable response = null; try { utx.begin(); Random rand = new Random(); String correlationId = rand.nextLong() + "-" + (new Date()).getTime(); // prepare the sending message object ObjectMessage reqMsg = session.createObjectMessage(); reqMsg.setObject(request); reqMsg.setJMSReplyTo(respDest); reqMsg.setJMSCorrelationID(correlationId); // prepare the publishers and subscribers MessageProducer producer = session.createProducer(reqDest); // send the message producer.send(reqMsg); System.out.println("Request Message has been sent!"); utx.commit(); // need to start second transaction, otherwise the first msg never gets sent utx.begin(); MessageConsumer consumer = session.createConsumer(respDest, "JMSCorrelationID = '" + correlationId + "'"); jmsConnection.start(); ObjectMessage respMsg = (ObjectMessage) consumer.receive(10000L); utx.commit(); if (respMsg != null) { response = respMsg.getObject(); System.out.println("Response Message has been received!"); } else { // timeout waiting for response System.out.println("Timeout waiting for response!"); } } catch (Exception e) { } return response; } SLSB 2 - LocationService.Java (only the reply method, rest is same as above) public boolean reply(Message origMsg, Serializable o) { boolean rc = false; try { // check if we have necessary correlationID and replyTo destination if (!origMsg.getJMSCorrelationID().equals("") && (origMsg.getJMSReplyTo() != null)) { // prepare the payload utx.begin(); ObjectMessage msg = session.createObjectMessage(); msg.setObject(o); // make it a response msg.setJMSCorrelationID(origMsg.getJMSCorrelationID()); Destination dest = origMsg.getJMSReplyTo(); // send it MessageProducer producer = session.createProducer(dest); producer.send(msg); producer.close(); System.out.println("Reply Message has been sent"); utx.commit(); rc = true; } } catch (Exception e) {} return rc; } sun-resources.xml <admin-object-resource enabled="true" jndi-name="jms/mvs.LocationControllerRequest" res-type="javax.jms.Queue" res-adapter="jmsra"> <property name="Name" value="mvs.LocationControllerRequestQueue"/> </admin-object-resource> <admin-object-resource enabled="true" jndi-name="jms/mvs.LocationControllerResponse" res-type="javax.jms.Queue" res-adapter="jmsra"> <property name="Name" value="mvs.LocationControllerResponseQueue"/> </admin-object-resource> <connector-connection-pool name="jms/mvs.MVSControllerFactoryPool" connection-definition-name="javax.jms.QueueConnectionFactory" resource-adapter-name="jmsra"/> <connector-resource enabled="true" jndi-name="jms/mvs.MVSControllerFactory" pool-name="jms/mvs.MVSControllerFactoryPool" />

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  • Cannot get official CentOS 5.4 BIND package to start

    - by Brian Cline
    Yesterday I installed CentOS 5.4 on one of my servers, and it appears that the official BIND/named package has trouble starting for reasons I cannot deduce. Here is what happens: [root@hal init.d]# service named start Starting named: Error in named configuration: /etc/named.conf:57: open: named.root.hints: permission denied [FAILED] The line in question, with the directory option for context: // further up in the file: directory "/var/named"; // line 57: include "named.root.hints"; Like you, my first reaction was to check permissions on /var/named/named.root.hints, /var/named, and /var to make sure the named user would be able to read it. Here are the permissions at each level: drwxr-xr-x 19 root root 4096 Nov 3 02:05 var drwxr-x--- 5 root named 4096 Nov 3 02:36 named -rw-r--r-- 1 named named 524 Mar 29 2006 named.root.hints Everything appears to be fine permission-wise. The same error occurs if the /var/named directory is writable by the named user. I've even temporarily allowed the named user to log in via bash, su'ed from root to named, and checked that I was, in fact, able to cat /var/named/named.root.hints successfully. (Yes, don't worry: I changed the shell back to nologin). My last endeavor showed that BIND is able to run under the named user account and start up just fine, if done so manually: [root@hal ~]# named -u named -g 03-Nov-2009 16:31:02.021 starting BIND 9.3.6-P1-RedHat-9.3.6-4.P1.el5 -u named -g 03-Nov-2009 16:31:02.021 adjusted limit on open files from 1024 to 1048576 03-Nov-2009 16:31:02.021 found 2 CPUs, using 2 worker threads 03-Nov-2009 16:31:02.021 using up to 4096 sockets 03-Nov-2009 16:31:02.028 loading configuration from '/etc/named.conf' 03-Nov-2009 16:31:02.030 using default UDP/IPv4 port range: [1024, 65535] 03-Nov-2009 16:31:02.031 using default UDP/IPv6 port range: [1024, 65535] 03-Nov-2009 16:31:02.034 listening on IPv4 interface lo, 127.0.0.1#53 03-Nov-2009 16:31:02.034 listening on IPv4 interface eth0, 10.0.0.5#53 03-Nov-2009 16:31:02.034 listening on IPv4 interface eth1, ww.xx.yy.zz#53 03-Nov-2009 16:31:02.040 command channel listening on 127.0.0.1#953 03-Nov-2009 16:31:02.040 command channel listening on ::1#953 03-Nov-2009 16:31:02.040 ignoring config file logging statement due to -g option 03-Nov-2009 16:31:02.041 zone 0.in-addr.arpa/IN/localhost_resolver: loaded serial 42 03-Nov-2009 16:31:02.042 zone 0.0.127.in-addr.arpa/IN/localhost_resolver: loaded serial 1997022700 03-Nov-2009 16:31:02.042 zone 255.in-addr.arpa/IN/localhost_resolver: loaded serial 42 03-Nov-2009 16:31:02.042 zone 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa/IN/localhost_resolver: loaded serial 1997022700 03-Nov-2009 16:31:02.043 zone localdomain/IN/localhost_resolver: loaded serial 42 03-Nov-2009 16:31:02.043 zone localhost/IN/localhost_resolver: loaded serial 42 03-Nov-2009 16:31:02.043 zone x.y.z.in-addr.arpa/IN/internal: loaded serial 1 03-Nov-2009 16:31:02.044 zone x.y.z/IN/internal: loaded serial 2 03-Nov-2009 16:31:02.045 running What type and size of firearm should I use to resolve this? I'd prefer something with automatic ammunition, and, at worst, it should be able to fit on my shoulder. Of course I am open to suggestions.

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