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  • Wake On Lan (WOL) for Realtek RTL8101E/RTL8102E

    - by Heisennberg
    I'm unsuccessfully trying to get Wake on Lan to work with my local server (IP Address : 192.168.0.2, distro Ubuntu 12.04.3 LTS) which has a Realtek RTL8101E/RTL8102E ethernet card. The computer sending the WOL is a Macbook Pro which is connected on the same network. Yet the server fails to start. Here what I have done so far : name@serverName ~ $ cat /proc/acpi/wakeup Device S-state Status Sysfs node HDEF S3 *disabled pci:0000:00:1b.0 PXSX S3 *disabled PXSX S0 *enabled pci:0000:04:00.0 PXSX S0 *disabled USB1 S3 *enabled pci:0000:00:1d.0 USB2 S3 *enabled pci:0000:00:1d.1 USB3 S3 *enabled pci:0000:00:1d.2 USB5 S3 *enabled pci:0000:00:1a.1 EHC1 S3 *enabled pci:0000:00:1d.7 EHC2 S3 *enabled pci:0000:00:1a.7 name@serverName ~ $ lspci ------ 04:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8101E/RTL8102E PCI Express Fast Ethernet controller (rev 01) ------ name@serverName ~ $ sudo ethtool eth0 Settings for eth0: Supported ports: [ TP MII ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full Supported pause frame use: No Supports auto-negotiation: Yes Advertised link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full Advertised pause frame use: Symmetric Receive-only Advertised auto-negotiation: Yes Link partner advertised link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full Link partner advertised pause frame use: Symmetric Receive-only Link partner advertised auto-negotiation: Yes Speed: 100Mb/s Duplex: Full Port: MII PHYAD: 0 Transceiver: internal Auto-negotiation: on Supports Wake-on: pumbg Wake-on: g Current message level: 0x00000033 (51) drv probe ifdown ifup Link detected: yes and I'm calling the WOL with : name@serverName ~ $ wakeonlan xx:xx:xx:xx:xx` Sending magic packet to 255.255.255.255:9 with xx:xx:xx:xx:xx I have succesfully activated the WOL option in my computer BIOS. Any idea ?

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  • How to tell if SPARC T4 crypto is being used?

    - by danx
    A question that often comes up when running applications on SPARC T4 systems is "How can I tell if hardware crypto accleration is being used?" To review, the SPARC T4 processor includes a crypto unit that supports several crypto instructions. For hardware crypto these include 11 AES instructions, 4 xmul* instructions (for AES GCM carryless multiply), mont for Montgomery multiply (optimizes RSA and DSA), and 5 des_* instructions (for DES3). For hardware hash algorithm optimization, the T4 has the md5, sha1, sha256, and sha512 instructions (the last two are used for SHA-224 an SHA-384). First off, it's easy to tell if the processor T4 crypto instructions—use the isainfo -v command and look for "sparcv9" and "aes" (and other hash and crypto algorithms) in the output: $ isainfo -v 64-bit sparcv9 applications crc32c cbcond pause mont mpmul sha512 sha256 sha1 md5 camellia kasumi des aes ima hpc vis3 fmaf asi_blk_init vis2 vis popc These instructions are not-privileged, so are available for direct use in user-level applications and libraries (such as OpenSSL). Here is the "openssl speed -evp" command shown with the built-in t4 engine and with the pkcs11 engine. Both run the T4 AES instructions, but the t4 engine is faster than the pkcs11 engine because it has less overhead (especially for smaller packet sizes): t-4 $ /usr/bin/openssl version OpenSSL 1.0.0j 10 May 2012 t-4 $ /usr/bin/openssl engine (t4) SPARC T4 engine support (dynamic) Dynamic engine loading support (pkcs11) PKCS #11 engine support t-4 $ /usr/bin/openssl speed -evp aes-128-cbc # t4 engine used by default . . . The 'numbers' are in 1000s of bytes per second processed. type 16 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes aes-128-cbc 487777.10k 816822.21k 986012.59k 1017029.97k 1053543.08k t-4 $ /usr/bin/openssl speed -engine pkcs11 -evp aes-128-cbc engine "pkcs11" set. . . . The 'numbers' are in 1000s of bytes per second processed. type 16 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes aes-128-cbc 31703.58k 116636.39k 350672.81k 696170.50k 993599.49k Note: The "-evp" flag indicates use the OpenSSL "EnVeloPe" API, which gives more accurate results. That's because it tells OpenSSL to use the same API that external programs use when calling OpenSSL libcrypto functions, evp(3openssl). DTrace Shows if T4 Crypto Functions Are Used OK, good enough, the isainfo(1) command shows the instructions are present, but how does one know if they are being used? Chi-Chang Lin, who works on Oracle Solaris performance, wrote a Dtrace script to show if T4 instructions are being executed. To show the T4 instructions are being used, run the following Dtrace script. Look for functions named "t4" and "yf" in the output. The OpenSSL T4 engine uses functions named "t4" and the PKCS#11 engine uses functions named "yf". To demonstrate, I'll first run "openssl speed" with the built-in t4 engine then with the pkcs11 engine. The performance numbers are not valid due to dtrace probes slowing things down. t-4 # dtrace -Z -n ' pid$target::*yf*:entry,pid$target::*t4_*:entry{ @[probemod, probefunc] = count();}' \ -c "/usr/bin/openssl speed -evp aes-128-cbc" dtrace: description 'pid$target::*yf*:entry' matched 101 probes . . . dtrace: pid 2029 has exited libcrypto.so.1.0.0 ENGINE_load_t4 1 libcrypto.so.1.0.0 t4_DH 1 libcrypto.so.1.0.0 t4_DSA 1 libcrypto.so.1.0.0 t4_RSA 1 libcrypto.so.1.0.0 t4_destroy 1 libcrypto.so.1.0.0 t4_free_aes_ctr_NIDs 1 libcrypto.so.1.0.0 t4_init 1 libcrypto.so.1.0.0 t4_add_NID 3 libcrypto.so.1.0.0 t4_aes_expand128 5 libcrypto.so.1.0.0 t4_cipher_init_aes 5 libcrypto.so.1.0.0 t4_get_all_ciphers 6 libcrypto.so.1.0.0 t4_get_all_digests 59 libcrypto.so.1.0.0 t4_digest_final_sha1 65 libcrypto.so.1.0.0 t4_digest_init_sha1 65 libcrypto.so.1.0.0 t4_sha1_multiblock 126 libcrypto.so.1.0.0 t4_digest_update_sha1 261 libcrypto.so.1.0.0 t4_aes128_cbc_encrypt 1432979 libcrypto.so.1.0.0 t4_aes128_load_keys_for_encrypt 1432979 libcrypto.so.1.0.0 t4_cipher_do_aes_128_cbc 1432979 t-4 # dtrace -Z -n 'pid$target::*yf*:entry{ @[probemod, probefunc] = count();}   pid$target::*yf*:entry,pid$target::*t4_*:entry{ @[probemod, probefunc] = count();}' \ -c "/usr/bin/openssl speed -engine pkcs11 -evp aes-128-cbc" dtrace: description 'pid$target::*yf*:entry' matched 101 probes engine "pkcs11" set. . . . dtrace: pid 2033 has exited libcrypto.so.1.0.0 ENGINE_load_t4 1 libcrypto.so.1.0.0 t4_DH 1 libcrypto.so.1.0.0 t4_DSA 1 libcrypto.so.1.0.0 t4_RSA 1 libcrypto.so.1.0.0 t4_destroy 1 libcrypto.so.1.0.0 t4_free_aes_ctr_NIDs 1 libcrypto.so.1.0.0 t4_get_all_ciphers 1 libcrypto.so.1.0.0 t4_get_all_digests 1 libsoftcrypto.so.1 rijndael_key_setup_enc_yf 1 libsoftcrypto.so.1 yf_aes_expand128 1 libcrypto.so.1.0.0 t4_add_NID 3 libsoftcrypto.so.1 yf_aes128_cbc_encrypt 1542330 libsoftcrypto.so.1 yf_aes128_load_keys_for_encrypt 1542330 So, as shown above the OpenSSL built-in t4 engine executes t4_* functions (which are hand-coded assembly executing the T4 AES instructions) and the OpenSSL pkcs11 engine executes *yf* functions. Programmatic Use of OpenSSL T4 engine The OpenSSL t4 engine is used automatically with the /usr/bin/openssl command line. Chi-Chang Lin also points out that if you're calling the OpenSSL API (libcrypto.so) from a program, you must call ENGINE_load_built_engines(), otherwise the built-in t4 engine will not be loaded. You do not call ENGINE_set_default(). That's because "openssl speed -evp" test calls ENGINE_load_built_engines() even though the "-engine" option wasn't specified. OpenSSL T4 engine Availability The OpenSSL t4 engine is available with Solaris 11 and 11.1. For Solaris 10 08/11 (U10), you need to use the OpenSSL pkcs311 engine. The OpenSSL t4 engine is distributed only with the version of OpenSSL distributed with Solaris (and not third-party or self-compiled versions of OpenSSL). The OpenSSL engine implements the AES cipher for Solaris 11, released 11/2011. For Solaris 11.1, released 11/2012, the OpenSSL engine adds optimization for the MD5, SHA-1, and SHA-2 hash algorithms, and DES-3. Although the T4 processor has Camillia and Kasumi block cipher instructions, these are not implemented in the OpenSSL T4 engine. The following charts may help view availability of optimizations. The first chart shows what's available with Solaris CLIs and APIs, the second chart shows what's available in Solaris OpenSSL. Native Solaris Optimization for SPARC T4 This table is shows Solaris native CLI and API support. As such, they are all available with the OpenSSL pkcs11 engine. CLIs: "openssl -engine pkcs11", encrypt(1), decrypt(1), mac(1), digest(1), MD5sum(1), SHA1sum(1), SHA224sum(1), SHA256sum(1), SHA384sum(1), SHA512sum(1) APIs: PKCS#11 library libpkcs11(3LIB) (incluDES Openssl pkcs11 engine), libMD(3LIB), and Solaris kernel modules AlgorithmSolaris 1008/11 (U10)Solaris 11Solaris 11.1 AES-ECB, AES-CBC, AES-CTR, AES-CBC AES-CFB128 XXX DES3-ECB, DES3-CBC, DES2-ECB, DES2-CBC, DES-ECB, DES-CBC XXX bignum Montgomery multiply (RSA, DSA) XXX MD5, SHA-1, SHA-256, SHA-384, SHA-512 XXX SHA-224 X ARCFOUR (RC4) X Solaris OpenSSL T4 Engine Optimization This table is for the Solaris OpenSSL built-in t4 engine. Algorithms listed above are also available through the OpenSSL pkcs11 engine. CLI: openssl(1openssl) APIs: openssl(5), engine(3openssl), evp(3openssl), libcrypto crypto(3openssl) AlgorithmSolaris 11Solaris 11SRU2Solaris 11.1 AES-ECB, AES-CBC, AES-CTR, AES-CBC AES-CFB128 XXX DES3-ECB, DES3-CBC, DES-ECB, DES-CBC X bignum Montgomery multiply (RSA, DSA) X MD5, SHA-1, SHA-256, SHA-384, SHA-512 XX SHA-224 X Source Code Availability Solaris Most of the T4 assembly code that called the new T4 crypto instructions was written by Ferenc Rákóczi of the Solaris Security group, with assistance from others. You can download the Solaris source for this and other parts of Solaris as a few zip files at the Oracle Download website. The relevant source files are generally under directories usr/src/common/crypto/{aes,arcfour,des,md5,modes,sha1,sha2}}/sun4v/. and usr/src/common/bignum/sun4v/. Solaris 11 binary is available from the Oracle Solaris 11 download website. OpenSSL t4 engine The source for the OpenSSL t4 engine, which is based on the Solaris source above, is viewable through the OpenGrok source code browser in directory src/components/openssl/openssl-1.0.0/engines/t4 . You can download the source from the same website or through Mercurial source code management, hg(1). Conclusion Oracle Solaris with SPARC T4 provides a rich set of accelerated cryptographic and hash algorithms. Using the latest update, Solaris 11.1, provides the best set of optimized algorithms, but alternatives are often available, sometimes slightly slower, for releases back to Solaris 10 08/11 (U10). Reference See also these earlier blogs. SPARC T4 OpenSSL Engine by myself, Dan Anderson (2011), discusses the Openssl T4 engine and reviews the SPARC T4 processor for the Solaris 11 release. Exciting Crypto Advances with the T4 processor and Oracle Solaris 11 by Valerie Fenwick (2011) discusses crypto algorithms that were optimized for the T4 processor with the Solaris 11 FCS (11/11) and Solaris 10 08/11 (U10) release. T4 Crypto Cheat Sheet by Stefan Hinker (2012) discusses how to make T4 crypto optimization available to various consumers (such as SSH, Java, OpenSSL, Apache, etc.) High Performance Security For Oracle Database and Fusion Middleware Applications using SPARC T4 (PDF, 2012) discusses SPARC T4 and its usage to optimize application security. Configuring Oracle iPlanet WebServer / Oracle Traffic Director to use crypto accelerators on T4-1 servers by Meena Vyas (2012)

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  • What is the advantage of currying?

    - by Mad Scientist
    I just learned about currying, and while I think I understand the concept, I'm not seeing any big advantage in using it. As a trivial example I use a function that adds two values (written in ML). The version without currying would be fun add(x, y) = x + y and would be called as add(3, 5) while the curried version is fun add x y = x + y (* short for val add = fn x => fn y=> x + y *) and would be called as add 3 5 It seems to me to be just syntactic sugar that removes one set of parentheses from defining and calling the function. I've seen currying listed as one of the important features of a functional languages, and I'm a bit underwhelmed by it at the moment. The concept of creating a chain of functions that consume each a single parameter, instead of a function that takes a tuple seems rather complicated to use for a simple change of syntax. Is the slightly simpler syntax the only motivation for currying, or am I missing some other advantages that are not obvious in my very simple example? Is currying just syntactic sugar?

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  • Find The Bug

    - by Alois Kraus
    What does this code print and why?             HashSet<int> set = new HashSet<int>();             int[] data = new int[] { 1, 2, 1, 2 };             var unique = from i in data                          where set.Add(i)                          select i;   // Compiles to: var unique = Enumerable.Where(data, (i) => set.Add(i));             foreach (var i in unique)             {                 Console.WriteLine("First: {0}", i);             }               foreach (var i in unique)             {                 Console.WriteLine("Second: {0}", i);             }   The output is: First: 1 First: 2 Why is there no output of the second loop? The reason is that LINQ does not cache the results of the collection but it does recalculate the contents for every new enumeration again. Since I have used state (the Hashset does decide which entries are part of the output) I do arrive with an empty sequence since Add of the Hashset will return false for all values I have already passed in leaving nothing to return a second time. The solution is quite simple: Use the Distinct extension method or cache the results by calling .ToList() or ToArray() for the result of the LINQ query. Lession Learned: Do never forget to think about state in Where clauses!

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  • xcopy file, suppress &ldquo;Does xxx specify a file name&hellip;&rdquo; message

    - by MarkPearl
    Today we had an interesting problem with file copying. We wanted to use xcopy to copy a file from one location to another and rename the copied file but do this impersonating another user. Getting the impersonation to work was fairly simple, however we then had the challenge of getting xcopy to work. The problem was that xcopy kept prompting us with a prompt similar to the following… Does file.xxx specify a file name or directory name on the target (F = file, D = directory)? At which point we needed to press ‘Y’. This seems to be a fairly common challenge with xcopy, as illustrated by the following stack overflow link… One of the solutions was to do the following… echo f | xcopy /f /y srcfile destfile This is fine if you are running from the command prompt, but if you are triggering this from c# how could we daisy chain a bunch of commands…. The solution was fairly simple, we eventually ended up with the following method… public void Copy(string initialFile, string targetFile) { string xcopyExe = @"C:\windows\system32\xcopy.exe"; string cmdExe = @"C:\windows\system32\cmd.exe"; ProcessStartInfo p = new ProcessStartInfo(); p.FileName = cmdExe; p.Arguments = string.Format(@"/c echo f | {2} {0} {1} /Y", initialFile, targetFile, xcopyExe); Process.Start(p); } Where we wrapped the commands we wanted to chain as arguments and instead of calling xcopy directly, we called cmd.exe passing xcopy as an argument.

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  • WSDL-world vs CLR-world – some differences

    - by nmarun
    A change in mindset is required when switching between a typical CLR application and a web service application. There are some things in a CLR environment that just don’t add-up in a WSDL arena (and vice-versa). I’m listing some of them here. When I say WSDL-world, I’m mostly talking with respect to a WCF Service and / or a Web Service. No (direct) Method Overloading: You definitely can have overloaded methods in a, say, Console application, but when it comes to a WCF / Web Services application, you need to adorn these overloaded methods with a special attribute so the service knows which specific method to invoke. When you’re working with WCF, use the Name property of the OperationContract attribute to provide unique names. 1: [OperationContract(Name = "AddInt")] 2: int Add(int arg1, int arg2); 3:  4: [OperationContract(Name = "AddDouble")] 5: double Add(double arg1, double arg2); By default, the proxy generates the code for this as: 1: [System.ServiceModel.OperationContractAttribute( 2: Action="http://tempuri.org/ILearnWcfService/AddInt", 3: ReplyAction="http://tempuri.org/ILearnWcfService/AddIntResponse")] 4: int AddInt(int arg1, int arg2); 5: 6: [System.ServiceModel.OperationContractAttribute( 7: Action="http://tempuri.org/ILearnWcfServiceExtend/AddDouble", 8: ReplyAction="http://tempuri.org/ILearnWcfServiceExtend/AddDoubleResponse")] 9: double AddDouble(double arg1, double arg2); With Web Services though the story is slightly different. Even after setting the MessageName property of the WebMethod attribute, the proxy does not change the name of the method, but only the underlying soap message changes. 1: [WebMethod] 2: public string HelloGalaxy() 3: { 4: return "Hello Milky Way!"; 5: } 6:  7: [WebMethod(MessageName = "HelloAnyGalaxy")] 8: public string HelloGalaxy(string galaxyName) 9: { 10: return string.Format("Hello {0}!", galaxyName); 11: } The one thing you need to remember is to set the WebServiceBinding accordingly. 1: [WebServiceBinding(ConformsTo = WsiProfiles.None)] The proxy is: 1: [System.Web.Services.Protocols.SoapDocumentMethodAttribute("http://tempuri.org/HelloGalaxy", 2: RequestNamespace="http://tempuri.org/", 3: ResponseNamespace="http://tempuri.org/", 4: Use=System.Web.Services.Description.SoapBindingUse.Literal, 5: ParameterStyle=System.Web.Services.Protocols.SoapParameterStyle.Wrapped)] 6: public string HelloGalaxy() 7:  8: [System.Web.Services.WebMethodAttribute(MessageName="HelloGalaxy1")] 9: [System.Web.Services.Protocols.SoapDocumentMethodAttribute("http://tempuri.org/HelloAnyGalaxy", 10: RequestElementName="HelloAnyGalaxy", 11: RequestNamespace="http://tempuri.org/", 12: ResponseElementName="HelloAnyGalaxyResponse", 13: ResponseNamespace="http://tempuri.org/", 14: Use=System.Web.Services.Description.SoapBindingUse.Literal, 15: ParameterStyle=System.Web.Services.Protocols.SoapParameterStyle.Wrapped)] 16: [return: System.Xml.Serialization.XmlElementAttribute("HelloAnyGalaxyResult")] 17: public string HelloGalaxy(string galaxyName) 18:  You see the calling method name is the same in the proxy, however the soap message that gets generated is different. Using interchangeable data types: See details on this here. Type visibility: In a CLR-based application, if you mark a field as private, well we all know, it’s ‘private’. Coming to a WSDL side of things, in a Web Service, private fields and web methods will not get generated in the proxy. In WCF however, all your operation contracts will be public as they get implemented from an interface. Even in case your ServiceContract interface is declared internal/private, you will see it as a public interface in the proxy. This is because type visibility is a CLR concept and has no bearing on WCF. Also if a private field has the [DataMember] attribute in a data contract, it will get emitted in the proxy class as a public property for the very same reason. 1: [DataContract] 2: public struct Person 3: { 4: [DataMember] 5: private int _x; 6:  7: [DataMember] 8: public int Id { get; set; } 9:  10: [DataMember] 11: public string FirstName { get; set; } 12:  13: [DataMember] 14: public string Header { get; set; } 15: } 16: } See the ‘_x’ field is a private member with the [DataMember] attribute, but the proxy class shows as below: 1: [System.Runtime.Serialization.DataMemberAttribute()] 2: public int _x { 3: get { 4: return this._xField; 5: } 6: set { 7: if ((this._xField.Equals(value) != true)) { 8: this._xField = value; 9: this.RaisePropertyChanged("_x"); 10: } 11: } 12: } Passing derived types to web methods / operation contracts: Once again, in a CLR application, I can have a derived class be passed as a parameter where a base class is expected. I have the following set up for my WCF service. 1: [DataContract] 2: public class Employee 3: { 4: [DataMember(Name = "Id")] 5: public int EmployeeId { get; set; } 6:  7: [DataMember(Name="FirstName")] 8: public string FName { get; set; } 9:  10: [DataMember] 11: public string Header { get; set; } 12: } 13:  14: [DataContract] 15: public class Manager : Employee 16: { 17: [DataMember] 18: private int _x; 19: } 20:  21: // service contract 22: [OperationContract] 23: Manager SaveManager(Employee employee); 24:  25: // in my calling code 26: Manager manager = new Manager {_x = 1, FirstName = "abc"}; 27: manager = LearnWcfServiceClient.SaveManager(manager); The above will throw an exception saying: In short, this is saying, that a Manager type was found where an Employee type was expected! Hierarchy flattening of interfaces in WCF: See details on this here. In CLR world, you’ll see the entire hierarchy as is. That’s another difference. Using ref parameters: * can use ref for parameters, but operation contract should not be one-way (gives an error when you do an update service reference)   => bad programming; create a return object that is composed of everything you need! This one kind of stumped me. Not sure why I tried this, but you can pass parameters prefixed with ref keyword* (* terms and conditions apply). The main issue is this, how would we know the changes that were made to a ‘ref’ input parameter are returned back from the service and updated to the local variable? Turns out both Web Services and WCF make this tracking happen by passing the input parameter in the response soap. This way when the deserializer does its magic, it maps all the elements of the response xml thereby updating our local variable. Here’s what I’m talking about. 1: [WebMethod(MessageName = "HelloAnyGalaxy")] 2: public string HelloGalaxy(ref string galaxyName) 3: { 4: string output = string.Format("Hello {0}", galaxyName); 5: if (galaxyName == "Andromeda") 6: { 7: galaxyName = string.Format("{0} (2.5 million light-years away)", galaxyName); 8: } 9: return output; 10: } This is how the request and response look like in soapUI. As I said above, the behavior is quite similar for WCF as well. But the catch comes when you have a one-way web methods / operation contracts. If you have an operation contract whose return type is void, is marked one-way and that has ref parameters then you’ll get an error message when you try to reference such a service. 1: [OperationContract(Name = "Sum", IsOneWay = true)] 2: void Sum(ref double arg1, ref double arg2); 3:  4: public void Sum(ref double arg1, ref double arg2) 5: { 6: arg1 += arg2; 7: } This is what I got when I did an update to my service reference: Makes sense, because a OneWay operation is… one-way – there’s no returning from this operation. You can also have a one-way web method: 1: [SoapDocumentMethod(OneWay = true)] 2: [WebMethod(MessageName = "HelloAnyGalaxy")] 3: public void HelloGalaxy(ref string galaxyName) This will throw an exception message similar to the one above when you try to update your web service reference. In the CLR space, there’s no such concept of a ‘one-way’ street! Yes, there’s void, but you very well can have ref parameters returned through such a method. Just a point here; although the ref/out concept sounds cool, it’s generally is a code-smell. The better approach is to always return an object that is composed of everything you need returned from a method. These are some of the differences that we need to bear when dealing with services that are different from our daily ‘CLR’ life.

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  • Java HttpURLConnection class Program

    - by pandu
    I am learning java. Here is the sample code of HttpURLConnection class usage in some text book import java.net.*; import java.io.*; import java.util.*; class HttpURLDemo { public static void main(String args[]) throws Exception { URL hp = new URL("http://www.google.com"); HttpURLConnection hpCon = (HttpURLConnection) hp.openConnection(); // Display request method. System.out.println("Request method is " + hpCon.getRequestMethod()); // Display response code. System.out.println("Response code is " + hpCon.getResponseCode()); // Display response message. System.out.println("Response Message is " + hpCon.getResponseMessage()); // Get a list of the header fields and a set // of the header keys. Map<String, List<String>> hdrMap = hpCon.getHeaderFields(); Set<String> hdrField = hdrMap.keySet(); System.out.println("\nHere is the header:"); // Display all header keys and values. for(String k : hdrField) { System.out.println("Key: " + k + " Value: " + hdrMap.get(k)); } } } Question is Why hpCon Object is declared in the following way? HttpURLConnection hpCon = (HttpURLConnection) hp.openConnection(); instead of declaring like this HttpURLConnection hpCon = new HttpURLConnection(); Author provided the following explanation. I cant understand Java provides a subclass of URLConnection that provides support for HTTP connections. This class is called HttpURLConnection. You obtain an HttpURLConnection in the same way just shown, by calling openConnection( ) on a URL object, but you must cast the result to HttpURLConnection. (Of course, you must make sure that you are actually opening an HTTP connection.) Once you have obtained a reference to an HttpURLConnection object, you can use any of the methods inherited from URLConnection

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  • Game Components, Game Managers and Object Properties

    - by George Duckett
    I'm trying to get my head around component based entity design. My first step was to create various components that could be added to an object. For every component type i had a manager, which would call every component's update function, passing in things like keyboard state etc. as required. The next thing i did was remove the object, and just have each component with an Id. So an object is defined by components having the same Ids. Now, i'm thinking that i don't need a manager for all my components, for example i have a SizeComponent, which just has a Size property). As a result the SizeComponent doesn't have an update method, and the manager's update method does nothing. My first thought was to have an ObjectProperty class which components could query, instead of having them as properties of components. So an object would have a number of ObjectProperty and ObjectComponent. Components would have update logic that queries the object for properties. The manager would manage calling the component's update method. This seems like over-engineering to me, but i don't think i can get rid of the components, because i need a way for the managers to know what objects need what component logic to run (otherwise i'd just remove the component completely and push its update logic into the manager). Is this (having ObjectProperty, ObjectComponent and ComponentManager classes) over-engineering? What would be a good alternative?

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  • Right-Time Retail Part 3

    - by David Dorf
    This is part three of the three-part series.  Read Part 1 and Part 2 first. Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Right-Time Marketing Real-time isn’t just about executing faster; it extends to interactions with customers as well. As an industry, we’ve spent many years analyzing all the data that’s been collected. Yes, that data has been invaluable in helping us make better decisions like where to open new stores, how to assort those stores, and how to price our products. But the recent advances in technology are now making it possible to analyze and deliver that data very quickly… fast enough to impact a potential sale in near real-time. Let me give you two examples. Salesmen in car dealerships get pretty good at sizing people up. When a potential customer walks in the door, it doesn’t take long for the salesman to figure out the revenue at stake. Is this person a real buyer, or just looking for a fun test drive? Will this person buy today or three months from now? Will this person opt for the expensive packages, or go bare bones? While the salesman certainly asks some leading questions, much of information is discerned through body language. But body language doesn’t translate very well over the web. Eloqua, which was acquired by Oracle earlier this year, reads internet body language. By tracking the behavior of the people visiting your web site, Eloqua categorizes visitors based on their propensity to buy. While Eloqua’s roots have been in B2B, we’ve been looking at leveraging the technology with ATG to target B2C. Knowing what sites were previously visited, how often the customer has been to your site recently, and how long they’ve spent searching can help understand where the customer is in their purchase journey. And knowing that bit of information may be enough to help close the deal with a real-time offer, follow-up email, or online customer service pop-up. This isn’t so different from the days gone by when the clerk behind the counter of the corner store noticed you were lingering in a particular aisle, so he walked over to help you compare two products and close the sale. You appreciated the personalized service, and he knew the value of the long-term relationship. Move that same concept into the digital world and you have Oracle’s CX Suite, a cloud-based offering of end-to-end customer experience tools, assembled primarily from acquisitions. Those tools are Oracle Marketing (Eloqua), Oracle Commerce (ATG, Endeca), Oracle Sales (Oracle CRM On Demand), Oracle Service (RightNow), Oracle Social (Collective Intellect, Vitrue, Involver), and Oracle Content (Fatwire). We are providing the glue that binds the CIO and CMO together to unleash synergies that drive the top-line higher, and by virtue of the cloud-approach, keep costs at bay. My second example of real-time marketing takes place in the store but leverages the concepts of Web marketing. In 1962 the decline of personalized service in retail began. Anyone know the significance of that year? That’s when Target, K-Mart, and Walmart each opened their first stores, and over the succeeding years the industry chose scale over personal service. No longer were you known as “Jane with the snotty kid so make sure we check her out fast,” but you suddenly became “time-starved female age 20-30 with kids.” I’m not saying that was a bad thing – it was the right thing for our industry at the time, and it enabled a huge amount of growth, cheaper prices, and more variety of products. But scale alone is no longer good enough. Today’s sophisticated consumer demands scale, experience, and personal attention. To some extent we’ve delivered that on websites via the magic of cookies, your willingness to log in, and sophisticated data analytics. What store manager wouldn’t love a report detailing all the visitors to his store, where they came from, and which products that examined? People trackers are getting more sophisticated, incorporating infrared, video analytics, and even face recognition. (Next time you walk in front on a mannequin, don’t be surprised if it’s looking back.) But the ultimate marketing conduit is the mobile phone. Since each mobile phone emits a unique number on WiFi networks, it becomes the cookie of the physical world. Assuming congress keeps privacy safeguards reasonable, we’ll have a win-win situation for both retailers and consumers. Retailers get to know more about the consumer’s purchase journey, and consumers get higher levels of service with the retailer. When I call my bank, a couple things happen before the call is connected. A reverse look-up on my phone number identifies me so my accounts can be retrieved from Siebel CRM. Then the system anticipates why I’m calling based on recent transactions. In this example, it sees that I was just charged a foreign currency fee, so it assumes that’s the reason I’m calling. It puts all the relevant information on the customer service rep’s screen as it connects the call. When I complain about the fee, the rep immediately sees I’m a great customer and I travel lots, so she suggests switching me to their traveler’s card that doesn’t have foreign transaction fees. That technology is powered by a product called Oracle Real-Time Decisions, a rules engine built to execute very quickly, basically in the time it takes the phone to ring once. So let’s combine the power of that product with our new-found mobile cookie and provide contextual customer interactions in real-time. Our first opportunity comes when a customer crosses a pre-defined geo-fence, typically a boundary around the store. Context is the key to our interaction: that’s the customer (known or anonymous), the time of day and day of week, and location. Thomas near the downtown store on a Wednesday at noon means he’s heading to lunch. If he were near the mall location on a Saturday morning, that’s a completely different context. But on his way to lunch, we’ll let Thomas know that we’ve got a new shipment of ASICS running shoes on display with a simple text message. We used the context to look-up Thomas’ past purchases and understood he was an avid runner. We used the fact that this was lunchtime to select the type of message, in this case an informational message instead of an offer. Thomas enters the store, phone in hand, and walks to the shoe department. He scans one of the new ASICS shoes using the convenient QR Codes we provided on the shelf-tags, but then he starts scanning low-end Nikes. Each scan is another opportunity to both learn from Thomas and potentially interact via another message. Since he historically buys low-end Nikes and keeps scanning them, he’s likely falling back into his old ways. Our marketing rules are currently set to move loyal customer to higher margin products. We could have set the dials to increase visit frequency, move overstocked items, increase basket size, or many other settings, but today we are trying to move Thomas to higher-margin products. We send Thomas another text message, this time it’s a personalized offer for 10% off ASICS good for 24 hours. Offering him a discount on Nikes would be throwing margin away since he buys those anyway. We are using our marketing dollars to change behavior that increases the long-term value of Thomas. He decides to buy the ASICS and scans the discount code on his phone at checkout. Checkout is yet another opportunity to interact with Thomas, so the transaction is sent back to Oracle RTD for evaluation. Since Thomas didn’t buy anything with the shoes, we’ll print a bounce-back coupon on the receipt offering 30% off ASICS socks if he returns within seven days. We have successfully started moving Thomas from low-margin to high-margin products. In both of these marketing scenarios, we are able to leverage data in near real-time to decide how best to interact with the customer and lead to an increase in the lifetime value of the customer. The key here is acting at the moment the customer shows interest using the context of the situation. We aren’t pushing random products at haphazard times. We are tailoring the marketing to be very specific to this customer, and it’s the technology that allows this to happen in near real-time. Conclusion As we enable more right-time integrations and interactions, retailers will begin to offer increased service to their customers. Localized and personalized service at scale will drive loyalty and lead to meaningful revenue growth for the retailers that execute well. Our industry needs to support Commerce Anywhere…and commerce anytime as well.

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  • Is it reasonable to expect knowing the whole stack bottom up?

    - by Vaibhav Garg
    I am an Sr. developer/architect/Product Manager for embedded systems. The systems that I have had experience with have typically been small to medium size codebases - typically close to 25-30K LOC in C, using 8-16 and 32 bit low end microcontrollers. The systems have been entirely bootstrapped by our team - meaning right from the start-up code to the end application code has either been written by the team, or at the very least, is thoroughly understood and maintained by us. Now, if we were to start developing more complex systems with complex peripherals, such as USB OTG et al. (think, low end cell phones), there are libraries and stacks available commercially and from chip vendors that reduce the task to just calling the right APIs and being able to use those peripherals. Now, from a habit point of view, this does not give me and the team a comfortable feeling, not being able to comprehend the entire code tree, with virtual black boxes at the lower layers. Is it reasonable to devote, and reserve, time getting into the details of how the APIs are implemented, assuming that the same would also entail getting into details of relevant standards (again, for USB as an example)? Or, alternatively, should a thorough understanding of the top level usage of the APIs be sufficient? This of course assumes that the source codes to all libraries are available, which they are, in almost all cases. Edit: In partial response to @Abhi Beckert, the documentation is refreshingly very comprehensive and meticulously maintained, AFAIK and been able to judge. I have not had a long experience with the same.

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  • DDD Model Design and Repository Persistence Performance Considerations

    - by agarhy
    So I have been reading about DDD for some time and trying to figure out the best approach on several issues. I tend to agree that I should design my model in a persistent agnostic manner. And that repositories should load and persist my models in valid states. But are these approaches realistic practically? I mean its normal for a model to hold a reference to a collection of another type. Persisting that model should mean persist the entire collection. Fine. But do I really need to load the entire collection every time I load the model? Probably not. So I can have specialized repositories. Some that load maybe a subset of the object graph via DTOs and others that load the entire object graph. But when do I use which? If I have DTOs, what's stopping client code from directly calling them and completely bypassing the model? I can have mappers and factories to create my models from DTOs maybe? But depending on the design of my models that might not always work. Or it might not allow my models to be created in a valid state. What's the correct approach here?

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  • How are events in games handled?

    - by Alex
    In may games that I have played, I have seen events being triggered, such as when you walk into a certain land area while holding a specific object, it will trigger a special creature to spawn. I was wondering, how do games deal with events such as this? Not in a specific game, but in general among games. The first thought I had was that each place has a hard-coded set of events that it will call when something happens there. However, that would be too inefficient to maintain, as when something new is added, that would require modification of every part of the game that would potentially cause the event to be called. Next up, I had the idea of maybe how GUI programming works. In all of the GUI programming I've done, you create a component and a callback function, or a listener. Then, when the user interacts when the button, the callback function is called, allowing you to do something with it. So, I was thinking that in terms of a game, when a land area gets loaded the game loops over a list of all events, creating instances of them and calling public methods to bind them to the current scene. The events themselves then handle what scene it is, and if it is a scene that pertains to the event, will call the public method of the scene to bind the event to an action. Then, when the action takes place, the scene would call all events that are bound to that action. However, I'm sure that's not how games would operate either, as that would require a lot of creating of events all the time. So how to video games handle events, are either of those methods correct, or is it something completely different?

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  • Fun with upgrading and BCP

    - by DavidWimbush
    I just had trouble with using BCP out via xp_cmdshell. Probably serves me right but that's a different issue. I got a strange error message 'Unable to resolve column level collations' which turned out to be a bit misleading. I wasted some time comparing the collations of the the server, the database and all the columns in the query. I got so desperate that I even read the Books Online article. Still no joy but then I tried the interweb. It turns out that calling bcp without qualifying it with a path causes Windows to search the folders listed in the Path environment variable - in that order - and execute the first version of BCP it can find. But when you do an in-place version upgrade, the new paths are added on the end of the Path variable so you don't get the latest version of BCP by default. To check which version you're getting execute bcp -v at the command line. The version number will correspond to SQL Server version numbering (eg. 10.50.n = 2008 R2). To examine and/or edit the Path variable, right-click on My Computer, select Properties, go to the Advanced tab and click on the Environment Variables button. If you change the variable you'll have to restart the SQL Server service before it takes effect.

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  • Are C++ templates just a kind of glorified macros?

    - by Gulshan
    From different comparisons among C++ templates and C#/Java generics like this one- http://stackoverflow.com/questions/31693/what-are-the-differences-between-generics-in-c-and-java-and-templates-in-c/31929#31929 I have a got a perception that, C++ templates are implemented by some kind of preprocessing, not compiling. In other words, they are just a kind of C macros. Is this right? Then I felt that, if C++ templates are implemented by preprocessing, dynamic linking(.dll) cannot be used. A quick google search also supports this. And lastly, how can we use macros in C to deliver C++ templates like functionalities? Another thing came in my mind about templates similar to some kind of preprocessor that, there can be integers passed as arguments to some templates. And it even supports kind of recursion. But the recursion is not in the assembly/machine code. So, am I wrong calling templates glorified macros? Unlike normal macros, it has some superior abilities. But isn't it a kind of preprocessing?

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  • Stack Trace Logger [migrated]

    - by Chris Okyen
    I need to write a parent Java class that classes using recursion can extend. The parent class will be be able to realize whenever the call stack changes ( you enter a method, temporarily leave it to go to another method call, or you are are finsihed with the method ) and then print it out. I want it to print on the console, but clear the console as well every time so it shows the stack horizantaly so you can see the height of each stack to see what popped off and what popped on... Also print out if a baseline was reached for recursive functions. First. How can I using the StackTraceElements and Thread classes to detect automatically whenever the stack has popped or pushed an element on without calling it manually? Second, how would I do the clearing thing? For instance , if I had the code: public class recursion(int i) { private static void recursion(int i) { if( i < 10) System.out.println('A'); else { recursion(i / 10 ); System.out.println('B'); } } public static void main(String[] argv) { recursion(102); } } It would need to print out the stack when entering main(), when entering recursion(102) from main(), when it enters recursion(102 / 10), which is recursion(10), from recursion(102), when it enters recursion(10 / 10), which is recursion(1) from recursion(10). Print out a message out when it reaches the baseline recursion(1).. then print out the stacks of reversed revisitation of function recursion(10), recursion(102) and main(). finally print out we are exiting main().

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  • how to think like a computer scientist java edition exercise 7.2 [on hold]

    - by James Canfield
    I cannot figure out how to write this program, can someone please help me?! The purpose of this method is to practice manipulating St rings. Create a new program called Name.java. This program will take a name string consisting of EITHER a first name followed by a last name (nonstandar d format) or a last name followed by a comma then a first name (standard format). Ie . “Joe Smith” vs. “Smith, Joe”. This program will convert the string to standard format if it is not already in standard format. Write a method called hasComma that takes a name as an argument and that returns a boolean indicating whether it contains a comma. If i t does, you can assume that it is in last name first format. You can use the indexOf String m ethod to help you. Write a method called convertName that takes a name as an argument. It should check whether it contains a comma by calling your hasComma method. If it does, it should just return the string. If not, then it should assume th at the name is in first name first format, and it should return a new string that contains the name converted to last name comma first format. Uses charAt, length, substring, and indexOf methods. In your main program, loop, asking the user for a n ame string. If the string is not blank, call convertName and print the results. The loop terminat es when the string is blank. HINTS/SUGGESTIONS: Use the charAt, length, substring, and indexOf Str ing methods. Use scanner for your input. To get the full line, complete with spaces, use reader.nextLine()

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  • Proper Data Structure for Commentable Comments

    - by Wesley
    Been struggling with this on an architectural level. I have an object which can be commented on, let's call it a Post. Every post has a unique ID. Now I want to comment on that Post, and I can use ID as a foreign key, and each PostComment has an ItemID field which correlates to the Post. Since each Post has a unique ID, it is very easy to assign "Top Level" comments. When I comment on a comment however, I feel like I now need a PostCommentComment, which attaches to the ID of the PostComment. Since ID's are assigned sequentially, I can no longer simply use ItemID to differentiate where in the tree the comment is assigned. I.E. both a Post and a Post Comment might have an ID of '5', so my foreign key relationship is invalid. This seems like it could go on infinitely, with PostCommentCommentComment's etc... What's the best way to solve this? Should I have a field in the comment called "IsPostComment" or something of the like to know which collection to attach the ID to? This strikes me as the best solution I've seen so far, but now I feel like I need to make recursive DataBase calls which start to get expensive. Meaning, I get a Post and get all PostComments where ItemID == Post.ID && where IsPostComment == true Then I take that as a collection, gather all the ID's of the PostComments, and do another search where ItemID == PostComment[all].ID && where IsPostComment == false, then repeat infinitely. This means I make a call for every layer, and if I'm calling 100 Posts, I might make 1000 DB calls to get 10 layers of comments each. What is the right way to do this?

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  • Distinction between API and frontend-backend

    - by Jason
    I'm trying to write a "standard" business web site. By "standard", I mean this site runs the usual HTML5, CSS and Javascript for the front-end, a back-end (to process stuff), and runs MySQL for the database. It's a basic CRUD site: the front-end just makes pretty whatever the database has in store; the backend writes to the database whatever the user enters and does some processing. Just like most sites out there. In creating my Github repositories to begin coding, I've realized I don't understand the distinction between the front-end back-end, and the API. Another way of phrasing my question is: where does the API come into this picture? I'm going to list some more details and then questions I have - hopefully this gives you guys a better idea of what my actual question is, because I'm so confused that I don't know the specific question to ask. Some more details: I'd like to try the Model-View-Controller pattern. I don't know if this changes the question/answer. The API will be RESTful I'd like my back-end to use my own API instead of allowing the back-end to cheat and call special queries. I think this style is more consistent. My questions: Does the front-end call the back-end which calls the API? Or does the front-end just call the API instead of calling the back-end? Does the back-end just execute an API and the API returns control to the back-end (where the back-end acts as the ultimate controller, delegating tasks)? Long and detailed answers explaining the role of the API alongside the front-end back-end are encouraged. If the answer depends on the model of programming (models other than the Model-View-Controller pattern), please describe these other ways of thinking of the API. Thanks. I'm very confused.

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  • Should one always know what an API is doing just by looking at the code?

    - by markmnl
    Recently I have been developing my own API and with that invested interest in API design I have been keenly interested how I can improve my API design. One aspect that has come up a couple times is (not by users of my API but in my observing discussion about the topic): one should know just by looking at the code calling the API what it is doing. For example see this discussion on GitHub for the discourse repo, it goes something like: foo.update_pinned(true, true); Just by looking at the code (without knowing the parameter names, documentation etc.) one cannot guess what it is going to do - what does the 2nd argument mean? The suggested improvement is to have something like: foo.pin() foo.unpin() foo.pin_globally() And that clears things up (the 2nd arg was whether to pin foo globally, I am guessing), and I agree in this case the later would certainly be an improvement. However I believe there can be instances where methods to set different but logically related state would be better exposed as one method call rather than separate ones, even though you would not know what it is doing just by looking at the code. (So you would have to resort to looking at the parameter names and documentation to find out - which personally I would always do no matter what if I am unfamiliar with an API). For example I expose one method SetVisibility(bool, string, bool) on a FalconPeer and I acknowledge just looking at the line: falconPeer.SetVisibility(true, "aerw3", true); You would have no idea what it is doing. It is setting 3 different values that control the "visibility" of the falconPeer in the logical sense: accept join requests, only with password and reply to discovery requests. Splitting this out into 3 method calls could lead to a user of the API to set one aspect of "visibility" forgetting to set others that I force them to think about by only exposing the one method to set all aspects of "visibility". Furthermore when the user wants to change one aspect they almost always will want to change another aspect and can now do so in one call.

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  • Consistency of an object

    - by Stefano Borini
    I tend to keep my objects consistent during their lifetime. In some cases, setting up an object requires multiple calls to different routines. For example, a connection object may operate in this way: Connection c = new Connection(); c.setHost("http://whatever") c.setPort(8080) c.connect() please note this is just a stupid example to let you understand the point. In between calls to setHost and setPort the object is inconsistent, because the Port has not been specified yet, so this code would crash Connection c = new Connection(); c.setHost("http://whatever") c.connect() Meaning that it's a requisite for connect() to have previous calls to both setHost and setPort, otherwise it won't be able to operate as its state is inconsistent. You may fix the issue with a default value, but there may be cases where no sensible default may be devised. We assume in the later example that there's no default for the port, and therefore a call to c.connect() without first calling both setHost and setPort will be an inconsistent state of the object. This, to me, points at an incorrect interface design, but I may be wrong, so I want to hear your opinion. Do you organize your interface so that the object is always in a consistent (i.e. workable) state both before and after the call ? Edit: Please don't try to solve the problem I gave above. I know how to solve that. My question is much broader in sense. I am looking for a design principle, officially or informally stated, regarding consistency of object state between calls.

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  • Implementing MVC pattern in SWT application

    - by Pradeep Simha
    I am developing an SWT application (it's basically an Eclipse plugin, so I need to use SWT). Currently my design is as follows: Model: In model, I have POJOs which represents the actual fields in views. View: It is a dumb layer, it contains just UI and contains no logic (not even event handlers) Controller: It acts as a mediator b/w those two layers. Also it is responsible for creating view layer, handling events etc. Basically I have created all of the controls in view as a static like this public static Button btnLogin and in controller I have a code like this: public void createLoginView(Composite comp) { LoginFormView.createView(comp); //This createView method is in view layer ie LoginFormView LoginFormView.btnLogin.addSelectionListener(new SelectionListener() { //Code goes here }); } Similalrly I have done for other views and controls. So that in main class and other classes I am calling just createLoginView of controller. I am doing similar thing for other views. So my question, is what I am doing is correct? Is this design good? Or I should have followed any other approach. Since I am new to SWT and Eclipse plugin development (basically I am Java EE developer having 4+ years of exp). Any tips/pointers would be appreciated.

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  • Coding Dynamic Events?

    - by Joey Green
    I have no idea what the title of this question should be so bare with me. My game has turns. On a turn a player does something and this can result in a random number of explosions that occur at different times. I know when the explosions are done. I need to know when ALL are done and then do some other action. Also, each explosion is the same amount of time, say 3 seconds.. Right now I'm thinking of using a counter to hold how many explosions are happening. Then once the explosion is finished decrement this counter. Once the counter is zero, do my action. This idea is inspired by objective-c memory management btw. Anyways, does this sound like a good approach or would there be another way. An alternative might be to figure out the explosion who happened last and let it be responsible for calling this subsequent action. I'm asking mostly, because I haven't done this before and am trying to figure out if there are bugs that may occur that I'm not foreseeing.

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  • How to Handle frame rates and synchronizing screen repaints

    - by David Kroukamp
    I would first off say sorry if the title is worded incorrectly. Okay now let me give the scenario I'm creating a 2 player fighting game, An average battle will include a Map (moving/still) and 2 characters (which are rendered by redrawing a varying amount of sprites one after the other). Now at the moment I have a single game loop limiting me to a set number of frames per second (using Java): Timer timer = new Timer(0, new AbstractAction() { @Override public void actionPerformed(ActionEvent e) { long beginTime; //The time when the cycle begun long timeDiff; //The time it took for the cycle to execute int sleepTime; //ms to sleep (< 0 if we're behind) int fps = 1000 / 40; beginTime = System.nanoTime() / 1000000; //execute loop to update check collisions and draw gameLoop(); //Calculate how long did the cycle take timeDiff = System.nanoTime() / 1000000 - beginTime; //Calculate sleep time sleepTime = fps - (int) (timeDiff); if (sleepTime > 0) {//If sleepTime > 0 we're OK ((Timer)e.getSource()).setDelay(sleepTime); } } }); timer.start(); in gameLoop() characters are drawn to the screen ( a character holds an array of images which consists of their current sprites) every gameLoop() call will change the characters current sprite to the next and loop if the end is reached. But as you can imagine if a sprite is only 3 images in length than calling gameLoop() 40 times will cause the characters movement to be drawn 40/3=13 times. This causes a few minor anomilies in the sprited for some charcters So my question is how would I go about delivering a set amount of frames per second in when I have 2 characters on screen with varying amount of sprites?

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  • Turn off Windows Defender on your builds

    - by george_v_reilly
    I've spent some time this evening profiling a Python application on Windows, trying to find out why it was so much slower than on Mac or Linux. The application is an in-house build tool which reads a number of config files, then writes some output files. Using the RunSnakeRun Python profile viewer on Windows, two things immediately leapt out at me: we were running os.stat a lot and file.close was really expensive. A quick test convinced me that we were stat-ing the same files over and over. It was a combination of explicit checks and implicit code, like os.walk calling os.path.isdir. I wrote a little cache that memoizes the results, which brought the cost of the os.stats down from 1.5 seconds to 0.6. Figuring out why closing files was so expensive was harder. I was writing 77 files, totaling just over 1MB, and it was taking 3.5 seconds. It turned out that it wasn't the UTF-8 codec or newline translation. It was simply that closing those files took far longer than it should have. I decided to try a different profiler, hoping to learn more. I downloaded the Windows Performance Toolkit. I recorded a couple of traces of my application running, then I looked at them in the Windows Performance Analyzer, whereupon I saw that in each case, the CPU spike of my app was followed by a CPU spike in MsMpEng.exe. What's MsMpEng.exe? It's Microsoft's antimalware engine, at the heart of Windows Defender. I added my build tree to the list of excluded locations, and my runtime halved. The 3.5 seconds of file closing dropped to 60 milliseconds, a 98% reduction. The moral of this story is: don't let your virus checker run on your builds.

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  • Cannot compile GDB7.8 with Python support

    - by j0h
    I am trying to install GDB7.8 with Python support. From the source folder, I am running ./configure --with-python When I did tab-complete from --with- I did not see Python in the list. But when I ran configure with that flag, it did not baulk. When I run make, it complains that Python is not found. checking for python2.7... no but Python is installed: $ which python python python2.7 python2.7-dbg-config python2 python2.7-dbg $ which python2.7 /usr/bin/python2.7 I compiled GDB without --with-python and things installed without error. I was under the impression that GDB7.8 had Python support without the need for special flags. But when I run: $gdb python (gdb) run test.py I get some sort of cannot import gdb Import error So then I tried calling "pi": (gdb) pi printf.py Python scripting is not supported in this copy of GDB. So... how do I get Python support in GDB7.8? is it actually not supported? Or should I not call "pi"?

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