Search Results

Search found 17487 results on 700 pages for 'static members'.

Page 148/700 | < Previous Page | 144 145 146 147 148 149 150 151 152 153 154 155  | Next Page >

  • Share data between local service and the hosting activity

    - by Moshik
    Hi, i need to share data between a local service and his hosting activity, i`am using sendBroadcast in order to send data to the hosting activity from the service, but if i want to send data back to the service from the hosting activity? so i though to create static method on the service, and call from the activity, and through it send the parameter, but then i cant do operations like toast inside that static method(which is inside the service).. coz you cant use "myclass.this" inside a static method, i guess there r more limits.. mybe another solution? mybe there is a proper way for this task? thanks, moshik.

    Read the article

  • PHP: extract email and name from data file

    - by pi-2r
    I need to extract the name and the e-mail from one data file. the file contains more than 500 lines and I want to extract this two informations almost all the data. I would like to use preg_match_all, but my function doesn't work ... $chaine = " ----------------- 11/21/12 16:06:54 tcp static-qvn-qvt-127041 MAIL [email protected] NAME tata1 ----------------- 11/21/12 16:06:54 tcp static-qvn-qvt-127041 MAIL [email protected] NAME tata2 * ----------------- 11/21/12 16:06:54 tcp static-qvn-qvt-127041 MAIL [email protected] NAME tata3 "; //$chaine =" #76:50#89:1#86:50#49:1#84:22"; $motif="/MAIL([a-z]{2,4}+)NAME([a-z]{2,4}+)/"; preg_match_all($motif,$chaine,$out); $nb=count($out[0]); for($i=0;$i<$nb;$i++) { echo $out[0][$i].'<br/>'; }

    Read the article

  • qmake library reordering

    - by user1095108
    I put this into a qmake file: QTPLUGIN += component LIBS += -L../lib -lmodule -lcomponent -lnetworking But qmake reorders the libraries behind my back: g++ -m64 -Wl,-O1,--sort-common,--as-needed,-z,relro -o testb .obj/constants.o .obj/main.o .obj/qrc_application.o -L/usr/lib -L../lib -lmodule -lnetworking -lcomponent -lQtGui -lQtNetwork -lQtCore -lpthread Probably because component is a static plugin. But it has a static dependency on the networking library and hence the reordering causes a link error. It is a static dependency and hence is ok in my opinion. How to work around this? I'm using qt 4.8.1.

    Read the article

  • Drupal 7 - change index.php as a default main page

    - by reycoy
    I'm trying to work on my new website Drupal7 while I'm keeping in the hosting my old static website. So I have: index.html (static website. I want to keep for my users) index.php (drupal new installation) Is there a way to set in drupal this kind of situation? The problem, as you problably can see at this point, is that every time I'm going to a different section I'm being redirected to the .html homepage. I mean for example the admin section is: www.mydomain.com/?q=admin instead of www.mydomain.com/index.php?q=admin What's the easiest way to keep the html static web for my current users while I'm developing my drupal7 website in the "background"?

    Read the article

  • C++ Inheritance Question

    - by shaz
    I have a base class MessageHandler and 2 derived classes, MessageHandler_CB and MessageHandler_DQ. The derived classes redefine the handleMessage(...) method. MH_DQ processes a message and puts the result in a deque while MH_CB processes the message and then executes a callback function. The base class has a static callback function that I pass along with a this pointer to a library which calls the static callback when a new message is available for processing. My problem comes when I am in the static callback with a void * pointing to either a MH_DQ or a MH_CB. If I cast it to the base class the empty MessageHandler::handleMessage(...) method is called, rather than the version in the appropriate derived class. What is the best way to address this situation from a design perspective and/or what language features might help me to implement a solution to my problem? Thanks in advance!

    Read the article

  • C++ template specialization

    - by user231536
    I have a class template <typename T> class C { static const int K=1; static ostream& print(ostream& os, const T& t) { return os << t;} }; I would like to specialize C for int. //specialization for int template <> C<int>{ static const int K=2; } I want the default print method that works for int to remain and just change the constant. For some specializations, I want to keep K=1 and change the print method because there is no << operator. How do I do this?

    Read the article

  • Why does the compiler give an ambiguous invocation error when passing inherited types?

    - by Matt Mitchell
    What is happening in the C# compiler to cause the following ambiguous invocation compilation error? The same issue applies to extension methods, or when TestClass is generic and using instance rather than static methods. class Type1 { } class Type2 : Type1 {} class TestClass { public static void Do<T>(T something, object o) where T : Type1 {} public static void Do(Type1 something, string o) {} } void Main() { var firstInstance = new Type1(); TestClass.Do(firstInstance, new object()); // Calls Do(Type1, obj) TestClass.Do(firstInstance, "Test"); // Calls Do<T>(T, string) var secondInstance = new Type2(); TestClass.Do(secondInstance, new object()); // Calls Do(Type1, obj) TestClass.Do(secondInstance, "Test"); // "The call is ambiguous" compile error }

    Read the article

  • Grails searchable plugin with hasMany

    - by user2624442
    I am using grails searchable plugin to search my domain classes. However, I cannot yet search by my hasMany (skills and interests) fields even though they are of the simple type String. This is my domain class: class EmpactUser { static searchable = [except: ['dateCreated','password','enabled','accountExpired','accountLocked','passwordExpired']] String username String password boolean enabled = true boolean accountExpired boolean accountLocked boolean passwordExpired String email String firstName String lastName String address String phoneNumber String description byte[] avatar byte[] resume Date dateCreated static hasMany = [ skills : String, interests : String, // each user has the ability to list many skills and interests so that they can be matched with a project. ] static constraints = { username blank: false, unique: true password blank: false email email: true, blank: false firstName blank: false lastName blank: false description nullable: true address nullable: true avatar nullable: true, maxSize: 1024 * 1024 * 10 resume nullable: true, maxSize: 1024 * 1024 * 10 phoneNumber nullable: true, matches: "/[(][+]d{3}[)]d+/", maxSize: 30 } } This is the code I am using to search: def empactUserList = EmpactUser.search( searchQuery, [reload: false, result: "every", defaultOperator: "or"]) Am I missing something? Thanks, Alan.

    Read the article

  • Accessing object's method within string

    - by Wild One
    Recently I was reading php documentation and found interesting note in string section: Functions, method calls, static class variables, and class constants inside {$} work since PHP 5. However, the value accessed will be interpreted as the name of a variable in the scope in which the string is defined. Using single curly braces ({}) will not work for accessing the return values of functions or methods or the values of class constants or static class variables. See www.php.net/manual/en/language.types.string.php It says, that I can't use curly syntax to get value returned by object's method call. Is it a mistake in manual or I misunderstood it, because I tried the following code and it works just fine: <?php class HelloWorld { public static function hello() { echo 'hello'; } } $a = new HelloWorld(); echo "{$a->hello()} world";

    Read the article

  • Where is the 'indeterminate type'?

    - by Daniel
    I'm defining the following type extension: type System.Reflection.MemberInfo with member x.GetAttribute<'T when 'T :> Attribute>(required, inherit') = match required, Attribute.GetCustomAttribute(x, typeof<'T>, inherit') with | true, null -> invalidOp (sprintf "Missing required attribute: %s" typeof<'T>.FullName) | _, attr -> attr :> 'T The last match expression (attr :> 'T) gives the error: The static coercion from Attribute to 'T involves an indeterminate type based on information prior to this program point. Static coercions are not allowed on some types. Further type annotations are needed. I've tried annotating the function return type, but got the same result. I would hate to change this to a dynamic cast. Is there a way to make the static cast work?

    Read the article

  • how toaccess the attributes in another form? c#

    - by Chelsea_cole
    I have a problem in a same namespace: public partial class frmForm1 : Form // Form1 { public class Account { public string Username; public string Password; } public class ListAcc { public static int count = 0; private static List<Account> UserList; public static List<Account> Data() { return UserList; } } } public partial class frmForm2 : Form // Form2 { private void button2_Click(object sender, EventArgs e) { frmForm1.Account A; string m = frmForm1.ListAcc<A>.[0].Username; //ERROR } } How could i access the attributes (Username, Password...) in frmForm1? Someone help me? Thanks!

    Read the article

  • CodeContracts: Possibly calling a method on a null reference

    - by dtb
    I'm having an argument with the CodeContracts static analysis tool. My code: class Foo { private static Foo instance = new Foo(); private string bar; public Foo() { bar = "Hello World"; } public static int BarLength() { return instance.bar.Length; // <<-- } } The tool tells me that instance.bar may be a null reference. I believe the opposite. Who is right? How can I prove it wrong?

    Read the article

  • Corona SDK - Make a character pass through a platform

    - by Andy Res
    I'm building a game that has a character which should jump up on multiple platforms. The jumping functionality is done, but I would like if the character is just below a platform (static body), when I press the "jump" button, the character should pass through that platform and then sit on it. Right now it collides with the platform, and character cannot jump on it. Do you have any idea how this can be achieved? Right now the platforms are represented by rectangles with "static" body type: local platform = display.newRect( 50, 280, 150, 10 ) platform:setFillColor ( 55, 55, 55) physics.addBody ( platform, "static", {density=1.0, friction=1.0, bounce=0 }) And I was thinking if I could change, or remove the body type of platform when the character collids with it, so he can pass trough platform, but I don't know how to do this, or in general if this will work... maybe there are some built in techniques on how to achieve the effect I want?

    Read the article

  • Django development server serving css but not js

    - by Wisco crew
    I am developing a django (1.4) app on my local machine. I am running the built-in development server with python manage.py runserver. In base.html I have: <link href="{{ STATIC_URL }}bootstrap.css" rel="stylesheet" type="text/css" /> <script src="{{ STATIC_URL }}boostrap-dropdown.js" type="text/javascript"></script> boostrap.css loads just fine when I load a page, but bootstrap-dropdown.js is 404'd. They are sitting right next to each other in my static directory. Relevant parts of settings.py: STATIC_URL = '/static/' STATICFILES_DIRS = ( '/home/username/projects/projectname/static',) Debug is set to True. I have tried it both with and without the staticfiles_urlpatterns trick. Django can find one file in the directory but not the other? I think I'm going crazy.

    Read the article

  • Windows Phone 7 Control Caching - 'Element is already the child of another element'

    - by will
    I'm trying to speed up my windows phone 7 page load times. I have a 'static' page that has a dynamically created in a Panorama control - static meaning that the content never changes. On the first load I look at my config file, create the individual PanoramaItem controls and add them to the main Panorama control. I'm trying to keep a List in a static place so that the initial creation would only happen once and I could just add a fully rendered version to my Panorama control when the page was rendered. Works fine on first load, but when I try to add the cached PanoramaItems to the Panorama control I get the message "Element is already the child of another element". This makes sense since I already added before. But I can see a way to disconnect the PanoramaItems with the first Panorama control... I could be going about the control caching thing all wrong as well... Let me know if there's another way to do this.

    Read the article

  • Singleton Creation preference

    - by cwieland
    You can create singletons in a variety of ways. I am wondering which is better between these. +(ServerConnection*)shared{ static dispatch_once_t pred=0; __strong static id _sharedObject = nil; dispatch_once(&pred, ^{ _sharedObject = [[self alloc] init]; // or some other init method }); return _sharedObject; } I could see that this compiles down to something very fast. I would think that checking the predicate would be another function call. The other is: +(ServerConnection*)shared{ static ServerConnection* connection=nil; if (connection==nil) { connection=[[ServerConnection alloc] init]; } return connection; } Are there any major differences between the two? I know these are probably similar enough to not worry about it. But Just wondering.

    Read the article

  • Efficient implementation of exclusive execution

    - by n0weak
    I have an ObjectManager class that is used to process payments. It is wrapped over the Order entities, so new instance has to be created when processing is required. I need to prevent the situation when several ObjectManager instances are dealing with the same order simultaneously (it happend once because of some errors on the remote payment processing center, somehow they called our callback urls twice). I'd love to get an advice how to implement it more efficiently. For now, I am thinking about something like that: public class OrderManager{ private static final CopyOnWriteArrayList<Integer> LOCKER = new CopyOnWriteArrayList<Integer>(); private static synchronized boolean tryLock(Integer key) { return LOCKER.addIfAbsent(key); } private static void releaseLock(Integer key) { LOCKER.remove(key); } public void processPayment(Integer orderId) throws Exception{ if (!tryLock(orderId)) { return; } try { //operate } finally { releaseLock(orderId); } } //remainder omitted }

    Read the article

  • Espeak SAPI/dll usage on Windows ?

    - by Quandary
    Question: I am trying to use the espeak text-to-speech engine. So for I got it working wounderfully on linux (code below). Now I wanted to port this basic program to windows, too, but it's nearly impossible... Part of the problem is that the windows dll only allows for AUDIO_OUTPUT_SYNCHRONOUS, which means it requires a callback, but I can't figure out how to play the audio from the callback... First it crashed, then I realized, I need a callback function, now I get the data in the callback function, but I don't know how to play it... as it is neither a wav file nor plays automatically as on Linux. The sourceforge site is rather useless, because it basically says use the SAPI version, but then there is no example on how to use the sapi espeak dll... Anyway, here's my code, can anybody help? #ifdef __cplusplus #include <cstdio> #include <cstdlib> #include <cstring> else #include <stdio.h> #include <stdlib.h> #include <string.h> endif include include //#include "speak_lib.h" include "espeak/speak_lib.h" // libespeak-dev: /usr/include/espeak/speak_lib.h // apt-get install libespeak-dev // apt-get install libportaudio-dev // g++ -o mine mine.cpp -lespeak // g++ -o mine mine.cpp -I/usr/include/espeak/ -lespeak // gcc -o mine mine.cpp -I/usr/include/espeak/ -lespeak char voicename[40]; int samplerate; int quiet = 0; static char genders[4] = {' ','M','F',' '}; //const char *data_path = "/usr/share/"; // /usr/share/espeak-data/ const char *data_path = NULL; // use default path for espeak-data int strrcmp(const char *s, const char *sub) { int slen = strlen(s); int sublen = strlen(sub); return memcmp(s + slen - sublen, sub, sublen); } char * strrcpy(char *dest, const char *source) { // Pre assertions assert(dest != NULL); assert(source != NULL); assert(dest != source); // tk: parentheses while((*dest++ = *source++)) ; return(--dest); } const char* GetLanguageVoiceName(const char* pszShortSign) { #define LANGUAGE_LENGTH 30 static char szReturnValue[LANGUAGE_LENGTH] ; memset(szReturnValue, 0, LANGUAGE_LENGTH); for (int i = 0; pszShortSign[i] != '\0'; ++i) szReturnValue[i] = (char) tolower(pszShortSign[i]); const espeak_VOICE **voices; espeak_VOICE voice_select; voices = espeak_ListVoices(NULL); const espeak_VOICE *v; for(int ix=0; (v = voices[ix]) != NULL; ix++) { if( !strrcmp( v->languages, szReturnValue) ) { strcpy(szReturnValue, v->name); return szReturnValue; } } // End for strcpy(szReturnValue, "default"); return szReturnValue; } // End function getvoicename void ListVoices() { const espeak_VOICE **voices; espeak_VOICE voice_select; voices = espeak_ListVoices(NULL); const espeak_VOICE *v; for(int ix=0; (v = voices[ix]) != NULL; ix++) { printf("Shortsign: %s\n", v->languages); printf("age: %d\n", v->age); printf("gender: %c\n", genders[v->gender]); printf("name: %s\n", v->name); printf("\n\n"); } // End for } // End function getvoicename int main() { printf("Hello World!\n"); const char* szVersionInfo = espeak_Info(NULL); printf("Espeak version: %s\n", szVersionInfo); samplerate = espeak_Initialize(AUDIO_OUTPUT_PLAYBACK,0,data_path,0); strcpy(voicename, "default"); // espeak --voices strcpy(voicename, "german"); strcpy(voicename, GetLanguageVoiceName("DE")); if(espeak_SetVoiceByName(voicename) != EE_OK) { printf("Espeak setvoice error...\n"); } static char word[200] = "Hello World" ; strcpy(word, "TV-fäns aufgepasst, es ist 20 Uhr 15. Zeit für Rambo 3"); strcpy(word, "Unnamed Player wurde zum Opfer von GSG9"); int speed = 220; int volume = 500; // volume in range 0-100 0=silence int pitch = 50; // base pitch, range 0-100. 50=normal // espeak.cpp 625 espeak_SetParameter(espeakRATE, speed, 0); espeak_SetParameter(espeakVOLUME,volume,0); espeak_SetParameter(espeakPITCH,pitch,0); // espeakRANGE: pitch range, range 0-100. 0-monotone, 50=normal // espeakPUNCTUATION: which punctuation characters to announce: // value in espeak_PUNCT_TYPE (none, all, some), espeak_VOICE *voice_spec = espeak_GetCurrentVoice(); voice_spec->gender=2; // 0=none 1=male, 2=female, //voice_spec->age = age; espeak_SetVoiceByProperties(voice_spec); espeak_Synth( (char*) word, strlen(word)+1, 0, POS_CHARACTER, 0, espeakCHARS_AUTO, NULL, NULL); espeak_Synchronize(); strcpy(voicename, GetLanguageVoiceName("EN")); espeak_SetVoiceByName(voicename); strcpy(word, "Geany was fragged by GSG9 Googlebot"); strcpy(word, "Googlebot"); espeak_Synth( (char*) word, strlen(word)+1, 0, POS_CHARACTER, 0, espeakCHARS_AUTO, NULL, NULL); espeak_Synchronize(); espeak_Terminate(); printf("Espeak terminated\n"); return EXIT_SUCCESS; } /* if(espeak_SetVoiceByName(voicename) != EE_OK) { memset(&voice_select,0,sizeof(voice_select)); voice_select.languages = voicename; if(espeak_SetVoiceByProperties(&voice_select) != EE_OK) { fprintf(stderr,"%svoice '%s'\n",err_load,voicename); exit(2); } } */ The above code is for Linux. The below code is about as far as I got on Vista x64 (32 bit emu): #ifdef __cplusplus #include <cstdio> #include <cstdlib> #include <cstring> else #include <stdio.h> #include <stdlib.h> #include <string.h> endif include include include "speak_lib.h" //#include "espeak/speak_lib.h" // libespeak-dev: /usr/include/espeak/speak_lib.h // apt-get install libespeak-dev // apt-get install libportaudio-dev // g++ -o mine mine.cpp -lespeak // g++ -o mine mine.cpp -I/usr/include/espeak/ -lespeak // gcc -o mine mine.cpp -I/usr/include/espeak/ -lespeak char voicename[40]; int iSampleRate; int quiet = 0; static char genders[4] = {' ','M','F',' '}; //const char *data_path = "/usr/share/"; // /usr/share/espeak-data/ //const char *data_path = NULL; // use default path for espeak-data const char *data_path = "C:\Users\Username\Desktop\espeak-1.43-source\espeak-1.43-source\"; int strrcmp(const char *s, const char *sub) { int slen = strlen(s); int sublen = strlen(sub); return memcmp(s + slen - sublen, sub, sublen); } char * strrcpy(char *dest, const char *source) { // Pre assertions assert(dest != NULL); assert(source != NULL); assert(dest != source); // tk: parentheses while((*dest++ = *source++)) ; return(--dest); } const char* GetLanguageVoiceName(const char* pszShortSign) { #define LANGUAGE_LENGTH 30 static char szReturnValue[LANGUAGE_LENGTH] ; memset(szReturnValue, 0, LANGUAGE_LENGTH); for (int i = 0; pszShortSign[i] != '\0'; ++i) szReturnValue[i] = (char) tolower(pszShortSign[i]); const espeak_VOICE **voices; espeak_VOICE voice_select; voices = espeak_ListVoices(NULL); const espeak_VOICE *v; for(int ix=0; (v = voices[ix]) != NULL; ix++) { if( !strrcmp( v->languages, szReturnValue) ) { strcpy(szReturnValue, v->name); return szReturnValue; } } // End for strcpy(szReturnValue, "default"); return szReturnValue; } // End function getvoicename void ListVoices() { const espeak_VOICE **voices; espeak_VOICE voice_select; voices = espeak_ListVoices(NULL); const espeak_VOICE *v; for(int ix=0; (v = voices[ix]) != NULL; ix++) { printf("Shortsign: %s\n", v->languages); printf("age: %d\n", v->age); printf("gender: %c\n", genders[v->gender]); printf("name: %s\n", v->name); printf("\n\n"); } // End for } // End function getvoicename /* Callback from espeak. Directly speaks using AudioTrack. */ define LOGI(x) printf("%s\n", x) static int AndroidEspeakDirectSpeechCallback(short *wav, int numsamples, espeak_EVENT *events) { char buf[100]; sprintf(buf, "AndroidEspeakDirectSpeechCallback: %d samples", numsamples); LOGI(buf); if (wav == NULL) { LOGI("Null: speech has completed"); } if (numsamples > 0) { //audout->write(wav, sizeof(short) * numsamples); sprintf(buf, "AudioTrack wrote: %d bytes", sizeof(short) * numsamples); LOGI(buf); } return 0; // continue synthesis (1 is to abort) } static int AndroidEspeakSynthToFileCallback(short *wav, int numsamples,espeak_EVENT *events) { char buf[100]; sprintf(buf, "AndroidEspeakSynthToFileCallback: %d samples", numsamples); LOGI(buf); if (wav == NULL) { LOGI("Null: speech has completed"); } // The user data should contain the file pointer of the file to write to //void* user_data = events->user_data; FILE* user_data = fopen ( "myfile1.wav" , "ab" ); FILE* fp = static_cast<FILE *>(user_data); // Write all of the samples fwrite(wav, sizeof(short), numsamples, fp); return 0; // continue synthesis (1 is to abort) } int main() { printf("Hello World!\n"); const char* szVersionInfo = espeak_Info(NULL); printf("Espeak version: %s\n", szVersionInfo); iSampleRate = espeak_Initialize(AUDIO_OUTPUT_SYNCHRONOUS, 4096, data_path, 0); if (iSampleRate <= 0) { printf("Unable to initialize espeak"); return EXIT_FAILURE; } //samplerate = espeak_Initialize(AUDIO_OUTPUT_PLAYBACK,0,data_path,0); //ListVoices(); strcpy(voicename, "default"); // espeak --voices //strcpy(voicename, "german"); //strcpy(voicename, GetLanguageVoiceName("DE")); if(espeak_SetVoiceByName(voicename) != EE_OK) { printf("Espeak setvoice error...\n"); } static char word[200] = "Hello World" ; strcpy(word, "TV-fäns aufgepasst, es ist 20 Uhr 15. Zeit für Rambo 3"); strcpy(word, "Unnamed Player wurde zum Opfer von GSG9"); int speed = 220; int volume = 500; // volume in range 0-100 0=silence int pitch = 50; // base pitch, range 0-100. 50=normal // espeak.cpp 625 espeak_SetParameter(espeakRATE, speed, 0); espeak_SetParameter(espeakVOLUME,volume,0); espeak_SetParameter(espeakPITCH,pitch,0); // espeakRANGE: pitch range, range 0-100. 0-monotone, 50=normal // espeakPUNCTUATION: which punctuation characters to announce: // value in espeak_PUNCT_TYPE (none, all, some), //espeak_VOICE *voice_spec = espeak_GetCurrentVoice(); //voice_spec->gender=2; // 0=none 1=male, 2=female, //voice_spec->age = age; //espeak_SetVoiceByProperties(voice_spec); //espeak_SetSynthCallback(AndroidEspeakDirectSpeechCallback); espeak_SetSynthCallback(AndroidEspeakSynthToFileCallback); unsigned int unique_identifier; espeak_ERROR err = espeak_Synth( (char*) word, strlen(word)+1, 0, POS_CHARACTER, 0, espeakCHARS_AUTO, &unique_identifier, NULL); err = espeak_Synchronize(); /* strcpy(voicename, GetLanguageVoiceName("EN")); espeak_SetVoiceByName(voicename); strcpy(word, "Geany was fragged by GSG9 Googlebot"); strcpy(word, "Googlebot"); espeak_Synth( (char*) word, strlen(word)+1, 0, POS_CHARACTER, 0, espeakCHARS_AUTO, NULL, NULL); espeak_Synchronize(); */ // espeak_Cancel(); espeak_Terminate(); printf("Espeak terminated\n"); system("pause"); return EXIT_SUCCESS; }

    Read the article

  • JSON error Caused by: java.lang.NullPointerException

    - by user3821853
    im trying to make a register page on android using JSON. everytime i press register button on avd, i get an error "unfortunately database has stopped". i have a error on my logcat that i cannot understand. this my code. please someone help me. this my register.java import android.app.Activity; import android.app.ProgressDialog; import android.os.AsyncTask; import android.os.Bundle; import android.util.Log; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.EditText; import android.widget.Toast; import org.apache.http.NameValuePair; import org.apache.http.message.BasicNameValuePair; import org.json.JSONException; import org.json.JSONObject; import java.util.ArrayList; import java.util.List; public class Register extends Activity implements OnClickListener{ private EditText user, pass; private Button mRegister; // Progress Dialog private ProgressDialog pDialog; // JSON parser class JSONParser jsonParser = new JSONParser(); //php register script //localhost : //testing on your device //put your local ip instead, on windows, run CMD > ipconfig //or in mac's terminal type ifconfig and look for the ip under en0 or en1 // private static final String REGISTER_URL = "http://xxx.xxx.x.x:1234/webservice/register.php"; //testing on Emulator: private static final String REGISTER_URL = "http://10.0.2.2:1234/webservice/register.php"; //testing from a real server: //private static final String REGISTER_URL = "http://www.mybringback.com/webservice/register.php"; //ids private static final String TAG_SUCCESS = "success"; private static final String TAG_MESSAGE = "message"; @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); setContentView(R.layout.register); user = (EditText)findViewById(R.id.username); pass = (EditText)findViewById(R.id.password); mRegister = (Button)findViewById(R.id.register); mRegister.setOnClickListener(this); } @Override public void onClick(View v) { // TODO Auto-generated method stub new CreateUser().execute(); } class CreateUser extends AsyncTask<String, String, String> { @Override protected void onPreExecute() { super.onPreExecute(); pDialog = new ProgressDialog(Register.this); pDialog.setMessage("Creating User..."); pDialog.setIndeterminate(false); pDialog.setCancelable(true); pDialog.show(); } @Override protected String doInBackground(String... args) { // TODO Auto-generated method stub // Check for success tag int success; String username = user.getText().toString(); String password = pass.getText().toString(); try { // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("username", username)); params.add(new BasicNameValuePair("password", password)); Log.d("request!", "starting"); //Posting user data to script JSONObject json = jsonParser.makeHttpRequest( REGISTER_URL, "POST", params); // full json response Log.d("Registering attempt", json.toString()); // json success element success = json.getInt(TAG_SUCCESS); if (success == 1) { Log.d("User Created!", json.toString()); finish(); return json.getString(TAG_MESSAGE); }else{ Log.d("Registering Failure!", json.getString(TAG_MESSAGE)); return json.getString(TAG_MESSAGE); } } catch (JSONException e) { e.printStackTrace(); } return null; } protected void onPostExecute(String file_url) { // dismiss the dialog once product deleted pDialog.dismiss(); if (file_url != null){ Toast.makeText(Register.this, file_url, Toast.LENGTH_LONG).show(); } } } } this is JSONparser.java import android.util.Log; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.NameValuePair; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.entity.UrlEncodedFormEntity; import org.apache.http.client.methods.HttpGet; import org.apache.http.client.methods.HttpPost; import org.apache.http.client.utils.URLEncodedUtils; import org.apache.http.impl.client.DefaultHttpClient; import org.json.JSONException; import org.json.JSONObject; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.UnsupportedEncodingException; import java.util.List; public class JSONParser { static InputStream is = null; static JSONObject jObj = null; static String json = ""; // constructor public JSONParser() { } public JSONObject getJSONFromUrl(final String url) { // Making HTTP request try { // Construct the client and the HTTP request. DefaultHttpClient httpClient = new DefaultHttpClient(); HttpPost httpPost = new HttpPost(url); // Execute the POST request and store the response locally. HttpResponse httpResponse = httpClient.execute(httpPost); // Extract data from the response. HttpEntity httpEntity = httpResponse.getEntity(); // Open an inputStream with the data content. is = httpEntity.getContent(); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } catch (ClientProtocolException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } try { // Create a BufferedReader to parse through the inputStream. BufferedReader reader = new BufferedReader(new InputStreamReader( is, "iso-8859-1"), 8); // Declare a string builder to help with the parsing. StringBuilder sb = new StringBuilder(); // Declare a string to store the JSON object data in string form. String line = null; // Build the string until null. while ((line = reader.readLine()) != null) { sb.append(line + "\n"); } // Close the input stream. is.close(); // Convert the string builder data to an actual string. json = sb.toString(); } catch (Exception e) { Log.e("Buffer Error", "Error converting result " + e.toString()); } // Try to parse the string to a JSON object try { jObj = new JSONObject(json); } catch (JSONException e) { Log.e("JSON Parser", "Error parsing data " + e.toString()); } // Return the JSON Object. return jObj; } // function get json from url // by making HTTP POST or GET mehtod public JSONObject makeHttpRequest(String url, String method, List<NameValuePair> params) { // Making HTTP request try { // check for request method if(method == "POST"){ // request method is POST // defaultHttpClient DefaultHttpClient httpClient = new DefaultHttpClient(); HttpPost httpPost = new HttpPost(url); httpPost.setEntity(new UrlEncodedFormEntity(params)); HttpResponse httpResponse = httpClient.execute(httpPost); HttpEntity httpEntity = httpResponse.getEntity(); is = httpEntity.getContent(); }else if(method == "GET"){ // request method is GET DefaultHttpClient httpClient = new DefaultHttpClient(); String paramString = URLEncodedUtils.format(params, "utf-8"); url += "?" + paramString; HttpGet httpGet = new HttpGet(url); HttpResponse httpResponse = httpClient.execute(httpGet); HttpEntity httpEntity = httpResponse.getEntity(); is = httpEntity.getContent(); } } catch (UnsupportedEncodingException e) { e.printStackTrace(); } catch (ClientProtocolException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } try { BufferedReader reader = new BufferedReader(new InputStreamReader( is, "iso-8859-1"), 8); StringBuilder sb = new StringBuilder(); String line = null; while ((line = reader.readLine()) != null) { sb.append(line + "\n"); } is.close(); json = sb.toString(); } catch (Exception e) { Log.e("Buffer Error", "Error converting result " + e.toString()); } // try parse the string to a JSON object try { jObj = new JSONObject(json); } catch (JSONException e) { Log.e("JSON Parser", "Error parsing data " + e.toString()); } // return JSON String return jObj; } } and this my error 08-18 23:40:02.381 2000-2018/com.example.blackcustomzier.database E/Buffer Error? Error converting result java.lang.NullPointerException: lock == null 08-18 23:40:02.381 2000-2018/com.example.blackcustomzier.database E/JSON Parser? Error parsing data org.json.JSONException: End of input at character 0 of 08-18 23:40:02.391 2000-2018/com.example.blackcustomzier.database W/dalvikvm? threadid=15: thread exiting with uncaught exception (group=0xb0f37648) 08-18 23:40:02.391 2000-2018/com.example.blackcustomzier.database E/AndroidRuntime? FATAL EXCEPTION: AsyncTask #4 java.lang.RuntimeException: An error occured while executing doInBackground() at android.os.AsyncTask$3.done(AsyncTask.java:299) at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352) at java.util.concurrent.FutureTask.setException(FutureTask.java:219) at java.util.concurrent.FutureTask.run(FutureTask.java:239) at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573) at java.lang.Thread.run(Thread.java:841) Caused by: java.lang.NullPointerException at com.example.blackcustomzier.database.Register$CreateUser.doInBackground(Register.java:108) at com.example.blackcustomzier.database.Register$CreateUser.doInBackground(Register.java:74) at android.os.AsyncTask$2.call(AsyncTask.java:287) at java.util.concurrent.FutureTask.run(FutureTask.java:234)             at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)             at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)             at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)             at java.lang.Thread.run(Thread.java:841) 08-18 23:40:02.501 2000-2000/com.example.blackcustomzier.database W/EGL_emulation? eglSurfaceAttrib not implemented 08-18 23:40:02.591 2000-2000/com.example.blackcustomzier.database W/EGL_emulation? eglSurfaceAttrib not implemented 08-18 23:40:02.981 2000-2000/com.example.blackcustomzier.database E/WindowManager? Activity com.example.blackcustomzier.database.Register has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{b1294c60 V.E..... R......D 0,0-1026,288} that was originally added here android.view.WindowLeaked: Activity com.example.blackcustomzier.database.Register has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{b1294c60 V.E..... R......D 0,0-1026,288} that was originally added here at android.view.ViewRootImpl.<init>(ViewRootImpl.java:345) at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:239) at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:69) at android.app.Dialog.show(Dialog.java:281) at com.example.blackcustomzier.database.Register$CreateUser.onPreExecute(Register.java:85) at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:586) at android.os.AsyncTask.execute(AsyncTask.java:534) at com.example.blackcustomzier.database.Register.onClick(Register.java:70) at android.view.View.performClick(View.java:4240) at android.view.View.onKeyUp(View.java:7928) at android.widget.TextView.onKeyUp(TextView.java:5606) at android.view.KeyEvent.dispatch(KeyEvent.java:2647) at android.view.View.dispatchKeyEvent(View.java:7343) at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1393) at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1393) at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1393) at android.view.ViewGroup.dispatchKeyEvent(ViewGroup.java:1393) at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchKeyEvent(PhoneWindow.java:1933) at com.android.internal.policy.impl.PhoneWindow.superDispatchKeyEvent(PhoneWindow.java:1408) at android.app.Activity.dispatchKeyEvent(Activity.java:2384) at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1860) at android.view.ViewRootImpl$ViewPostImeInputStage.processKeyEvent(ViewRootImpl.java:3791) at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:3774) at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3379) at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3429) at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3398) at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3483) at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3406) at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:3540) at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3379) at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3429) at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3398) at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3406) at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3379) at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3429) at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3398) at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3516) at android.view.ViewRootImpl$ImeInputStage.onFinishedInputEvent(ViewRootImpl.java:3666) at android.view.inputmethod.InputMethodManager$PendingEvent.run(InputMethodManager.java:1982) at android.view.inputmethod.InputMethodManager.invokeFinishedInputEventCallback(InputMethodManager.java:1698) at android.view.inputmethod.InputMethodManager.finishedInputEvent(InputMethodManager.java:1689) at android.view.inputmethod.InputMethodManager$ImeInputEventSender.onInputEventFinished(InputMethodManager.java:1959) at android.view.InputEventSender.dispatchInputEventFinished(InputEventSender.java:141) at android.os.MessageQueue.nativePollOnce(Native Method) at android.os.MessageQueue.next(MessageQueue.java:132) at android.os.Looper.loop(Looper.java:124) at android.app.ActivityThread.main(ActivityThread.java:5103) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:525) at com.android.internal.os.ZygoteInit$MethodAndArgsCal please help me to solve this thx

    Read the article

  • Using FiddlerCore to capture HTTP Requests with .NET

    - by Rick Strahl
    Over the last few weeks I’ve been working on my Web load testing utility West Wind WebSurge. One of the key components of a load testing tool is the ability to capture URLs effectively so that you can play them back later under load. One of the options in WebSurge for capturing URLs is to use its built-in capture tool which acts as an HTTP proxy to capture any HTTP and HTTPS traffic from most Windows HTTP clients, including Web Browsers as well as standalone Windows applications and services. To make this happen, I used Eric Lawrence’s awesome FiddlerCore library, which provides most of the functionality of his desktop Fiddler application, all rolled into an easy to use library that you can plug into your own applications. FiddlerCore makes it almost too easy to capture HTTP content! For WebSurge I needed to capture all HTTP traffic in order to capture the full HTTP request – URL, headers and any content posted by the client. The result of what I ended up creating is this semi-generic capture form: In this post I’m going to demonstrate how easy it is to use FiddlerCore to build this HTTP Capture Form.  If you want to jump right in here are the links to get Telerik’s Fiddler Core and the code for the demo provided here. FiddlerCore Download FiddlerCore on NuGet Show me the Code (WebSurge Integration code from GitHub) Download the WinForms Sample Form West Wind Web Surge (example implementation in live app) Note that FiddlerCore is bound by a license for commercial usage – see license.txt in the FiddlerCore distribution for details. Integrating FiddlerCore FiddlerCore is a library that simply plugs into your application. You can download it from the Telerik site and manually add the assemblies to your project, or you can simply install the NuGet package via:       PM> Install-Package FiddlerCore The library consists of the FiddlerCore.dll as well as a couple of support libraries (CertMaker.dll and BCMakeCert.dll) that are used for installing SSL certificates. I’ll have more on SSL captures and certificate installation later in this post. But first let’s see how easy it is to use FiddlerCore to capture HTTP content by looking at how to build the above capture form. Capturing HTTP Content Once the library is installed it’s super easy to hook up Fiddler functionality. Fiddler includes a number of static class methods on the FiddlerApplication object that can be called to hook up callback events as well as actual start monitoring HTTP URLs. In the following code directly lifted from WebSurge, I configure a few filter options on Form level object, from the user inputs shown on the form by assigning it to a capture options object. In the live application these settings are persisted configuration values, but in the demo they are one time values initialized and set on the form. Once these options are set, I hook up the AfterSessionComplete event to capture every URL that passes through the proxy after the request is completed and start up the Proxy service:void Start() { if (tbIgnoreResources.Checked) CaptureConfiguration.IgnoreResources = true; else CaptureConfiguration.IgnoreResources = false; string strProcId = txtProcessId.Text; if (strProcId.Contains('-')) strProcId = strProcId.Substring(strProcId.IndexOf('-') + 1).Trim(); strProcId = strProcId.Trim(); int procId = 0; if (!string.IsNullOrEmpty(strProcId)) { if (!int.TryParse(strProcId, out procId)) procId = 0; } CaptureConfiguration.ProcessId = procId; CaptureConfiguration.CaptureDomain = txtCaptureDomain.Text; FiddlerApplication.AfterSessionComplete += FiddlerApplication_AfterSessionComplete; FiddlerApplication.Startup(8888, true, true, true); } The key lines for FiddlerCore are just the last two lines of code that include the event hookup code as well as the Startup() method call. Here I only hook up to the AfterSessionComplete event but there are a number of other events that hook various stages of the HTTP request cycle you can also hook into. Other events include BeforeRequest, BeforeResponse, RequestHeadersAvailable, ResponseHeadersAvailable and so on. In my case I want to capture the request data and I actually have several options to capture this data. AfterSessionComplete is the last event that fires in the request sequence and it’s the most common choice to capture all request and response data. I could have used several other events, but AfterSessionComplete is one place where you can look both at the request and response data, so this will be the most common place to hook into if you’re capturing content. The implementation of AfterSessionComplete is responsible for capturing all HTTP request headers and it looks something like this:private void FiddlerApplication_AfterSessionComplete(Session sess) { // Ignore HTTPS connect requests if (sess.RequestMethod == "CONNECT") return; if (CaptureConfiguration.ProcessId > 0) { if (sess.LocalProcessID != 0 && sess.LocalProcessID != CaptureConfiguration.ProcessId) return; } if (!string.IsNullOrEmpty(CaptureConfiguration.CaptureDomain)) { if (sess.hostname.ToLower() != CaptureConfiguration.CaptureDomain.Trim().ToLower()) return; } if (CaptureConfiguration.IgnoreResources) { string url = sess.fullUrl.ToLower(); var extensions = CaptureConfiguration.ExtensionFilterExclusions; foreach (var ext in extensions) { if (url.Contains(ext)) return; } var filters = CaptureConfiguration.UrlFilterExclusions; foreach (var urlFilter in filters) { if (url.Contains(urlFilter)) return; } } if (sess == null || sess.oRequest == null || sess.oRequest.headers == null) return; string headers = sess.oRequest.headers.ToString(); var reqBody = sess.GetRequestBodyAsString(); // if you wanted to capture the response //string respHeaders = session.oResponse.headers.ToString(); //var respBody = session.GetResponseBodyAsString(); // replace the HTTP line to inject full URL string firstLine = sess.RequestMethod + " " + sess.fullUrl + " " + sess.oRequest.headers.HTTPVersion; int at = headers.IndexOf("\r\n"); if (at < 0) return; headers = firstLine + "\r\n" + headers.Substring(at + 1); string output = headers + "\r\n" + (!string.IsNullOrEmpty(reqBody) ? reqBody + "\r\n" : string.Empty) + Separator + "\r\n\r\n"; BeginInvoke(new Action<string>((text) => { txtCapture.AppendText(text); UpdateButtonStatus(); }), output); } The code starts by filtering out some requests based on the CaptureOptions I set before the capture is started. These options/filters are applied when requests actually come in. This is very useful to help narrow down the requests that are captured for playback based on options the user picked. I find it useful to limit requests to a certain domain for captures, as well as filtering out some request types like static resources – images, css, scripts etc. This is of course optional, but I think it’s a common scenario and WebSurge makes good use of this feature. AfterSessionComplete like other FiddlerCore events, provides a Session object parameter which contains all the request and response details. There are oRequest and oResponse objects to hold their respective data. In my case I’m interested in the raw request headers and body only, as you can see in the commented code you can also retrieve the response headers and body. Here the code captures the request headers and body and simply appends the output to the textbox on the screen. Note that the Fiddler events are asynchronous, so in order to display the content in the UI they have to be marshaled back the UI thread with BeginInvoke, which here simply takes the generated headers and appends it to the existing textbox test on the form. As each request is processed, the headers are captured and appended to the bottom of the textbox resulting in a Session HTTP capture in the format that Web Surge internally supports, which is basically raw request headers with a customized 1st HTTP Header line that includes the full URL rather than a server relative URL. When the capture is done the user can either copy the raw HTTP session to the clipboard, or directly save it to file. This raw capture format is the same format WebSurge and also Fiddler use to import/export request data. While this code is application specific, it demonstrates the kind of logic that you can easily apply to the request capture process, which is one of the reasonsof why FiddlerCore is so powerful. You get to choose what content you want to look up as part of your own application logic and you can then decide how to capture or use that data as part of your application. The actual captured data in this case is only a string. The user can edit the data by hand or in the the case of WebSurge, save it to disk and automatically open the captured session as a new load test. Stopping the FiddlerCore Proxy Finally to stop capturing requests you simply disconnect the event handler and call the FiddlerApplication.ShutDown() method:void Stop() { FiddlerApplication.AfterSessionComplete -= FiddlerApplication_AfterSessionComplete; if (FiddlerApplication.IsStarted()) FiddlerApplication.Shutdown(); } As you can see, adding HTTP capture functionality to an application is very straight forward. FiddlerCore offers tons of features I’m not even touching on here – I suspect basic captures are the most common scenario, but a lot of different things can be done with FiddlerCore’s simple API interface. Sky’s the limit! The source code for this sample capture form (WinForms) is provided as part of this article. Adding Fiddler Certificates with FiddlerCore One of the sticking points in West Wind WebSurge has been that if you wanted to capture HTTPS/SSL traffic, you needed to have the full version of Fiddler and have HTTPS decryption enabled. Essentially you had to use Fiddler to configure HTTPS decryption and the associated installation of the Fiddler local client certificate that is used for local decryption of incoming SSL traffic. While this works just fine, requiring to have Fiddler installed and then using a separate application to configure the SSL functionality isn’t ideal. Fortunately FiddlerCore actually includes the tools to register the Fiddler Certificate directly using FiddlerCore. Why does Fiddler need a Certificate in the first Place? Fiddler and FiddlerCore are essentially HTTP proxies which means they inject themselves into the HTTP conversation by re-routing HTTP traffic to a special HTTP port (8888 by default for Fiddler) and then forward the HTTP data to the original client. Fiddler injects itself as the system proxy in using the WinInet Windows settings  which are the same settings that Internet Explorer uses and that are configured in the Windows and Internet Explorer Internet Settings dialog. Most HTTP clients running on Windows pick up and apply these system level Proxy settings before establishing new HTTP connections and that’s why most clients automatically work once Fiddler – or FiddlerCore/WebSurge are running. For plain HTTP requests this just works – Fiddler intercepts the HTTP requests on the proxy port and then forwards them to the original port (80 for HTTP and 443 for SSL typically but it could be any port). For SSL however, this is not quite as simple – Fiddler can easily act as an HTTPS/SSL client to capture inbound requests from the server, but when it forwards the request to the client it has to also act as an SSL server and provide a certificate that the client trusts. This won’t be the original certificate from the remote site, but rather a custom local certificate that effectively simulates an SSL connection between the proxy and the client. If there is no custom certificate configured for Fiddler the SSL request fails with a certificate validation error. The key for this to work is that a custom certificate has to be installed that the HTTPS client trusts on the local machine. For a much more detailed description of the process you can check out Eric Lawrence’s blog post on Certificates. If you’re using the desktop version of Fiddler you can install a local certificate into the Windows certificate store. Fiddler proper does this from the Options menu: This operation does several things: It installs the Fiddler Root Certificate It sets trust to this Root Certificate A new client certificate is generated for each HTTPS site monitored Certificate Installation with FiddlerCore You can also provide this same functionality using FiddlerCore which includes a CertMaker class. Using CertMaker is straight forward to use and it provides an easy way to create some simple helpers that can install and uninstall a Fiddler Root certificate:public static bool InstallCertificate() { if (!CertMaker.rootCertExists()) { if (!CertMaker.createRootCert()) return false; if (!CertMaker.trustRootCert()) return false; } return true; } public static bool UninstallCertificate() { if (CertMaker.rootCertExists()) { if (!CertMaker.removeFiddlerGeneratedCerts(true)) return false; } return true; } InstallCertificate() works by first checking whether the root certificate is already installed and if it isn’t goes ahead and creates a new one. The process of creating the certificate is a two step process – first the actual certificate is created and then it’s moved into the certificate store to become trusted. I’m not sure why you’d ever split these operations up since a cert created without trust isn’t going to be of much value, but there are two distinct steps. When you trigger the trustRootCert() method, a message box will pop up on the desktop that lets you know that you’re about to trust a local private certificate. This is a security feature to ensure that you really want to trust the Fiddler root since you are essentially installing a man in the middle certificate. It’s quite safe to use this generated root certificate, because it’s been specifically generated for your machine and thus is not usable from external sources, the only way to use this certificate in a trusted way is from the local machine. IOW, unless somebody has physical access to your machine, there’s no useful way to hijack this certificate and use it for nefarious purposes (see Eric’s post for more details). Once the Root certificate has been installed, FiddlerCore/Fiddler create new certificates for each site that is connected to with HTTPS. You can end up with quite a few temporary certificates in your certificate store. To uninstall you can either use Fiddler and simply uncheck the Decrypt HTTPS traffic option followed by the remove Fiddler certificates button, or you can use FiddlerCore’s CertMaker.removeFiddlerGeneratedCerts() which removes the root cert and any of the intermediary certificates Fiddler created. Keep in mind that when you uninstall you uninstall the certificate for both FiddlerCore and Fiddler, so use UninstallCertificate() with care and realize that you might affect the Fiddler application’s operation by doing so as well. When to check for an installed Certificate Note that the check to see if the root certificate exists is pretty fast, while the actual process of installing the certificate is a relatively slow operation that even on a fast machine takes a few seconds. Further the trust operation pops up a message box so you probably don’t want to install the certificate repeatedly. Since the check for the root certificate is fast, you can easily put a call to InstallCertificate() in any capture startup code – in which case the certificate installation only triggers when a certificate is in fact not installed. Personally I like to make certificate installation explicit – just like Fiddler does, so in WebSurge I use a small drop down option on the menu to install or uninstall the SSL certificate:   This code calls the InstallCertificate and UnInstallCertificate functions respectively – the experience with this is similar to what you get in Fiddler with the extra dialog box popping up to prompt confirmation for installation of the root certificate. Once the cert is installed you can then capture SSL requests. There’s a gotcha however… Gotcha: FiddlerCore Certificates don’t stick by Default When I originally tried to use the Fiddler certificate installation I ran into an odd problem. I was able to install the certificate and immediately after installation was able to capture HTTPS requests. Then I would exit the application and come back in and try the same HTTPS capture again and it would fail due to a missing certificate. CertMaker.rootCertExists() would return false after every restart and if re-installed the certificate a new certificate would get added to the certificate store resulting in a bunch of duplicated root certificates with different keys. What the heck? CertMaker and BcMakeCert create non-sticky CertificatesI turns out that FiddlerCore by default uses different components from what the full version of Fiddler uses. Fiddler uses a Windows utility called MakeCert.exe to create the Fiddler Root certificate. FiddlerCore however installs the CertMaker.dll and BCMakeCert.dll assemblies, which use a different crypto library (Bouncy Castle) for certificate creation than MakeCert.exe which uses the Windows Crypto API. The assemblies provide support for non-windows operation for Fiddler under Mono, as well as support for some non-Windows certificate platforms like iOS and Android for decryption. The bottom line is that the FiddlerCore provided bouncy castle assemblies are not sticky by default as the certificates created with them are not cached as they are in Fiddler proper. To get certificates to ‘stick’ you have to explicitly cache the certificates in Fiddler’s internal preferences. A cache aware version of InstallCertificate looks something like this:public static bool InstallCertificate() { if (!CertMaker.rootCertExists()) { if (!CertMaker.createRootCert()) return false; if (!CertMaker.trustRootCert()) return false; App.Configuration.UrlCapture.Cert = FiddlerApplication.Prefs.GetStringPref("fiddler.certmaker.bc.cert", null); App.Configuration.UrlCapture.Key = FiddlerApplication.Prefs.GetStringPref("fiddler.certmaker.bc.key", null); } return true; } public static bool UninstallCertificate() { if (CertMaker.rootCertExists()) { if (!CertMaker.removeFiddlerGeneratedCerts(true)) return false; } App.Configuration.UrlCapture.Cert = null; App.Configuration.UrlCapture.Key = null; return true; } In this code I store the Fiddler cert and private key in an application configuration settings that’s stored with the application settings (App.Configuration.UrlCapture object). These settings automatically persist when WebSurge is shut down. The values are read out of Fiddler’s internal preferences store which is set after a new certificate has been created. Likewise I clear out the configuration settings when the certificate is uninstalled. In order for these setting to be used you have to also load the configuration settings into the Fiddler preferences *before* a call to rootCertExists() is made. I do this in the capture form’s constructor:public FiddlerCapture(StressTestForm form) { InitializeComponent(); CaptureConfiguration = App.Configuration.UrlCapture; MainForm = form; if (!string.IsNullOrEmpty(App.Configuration.UrlCapture.Cert)) { FiddlerApplication.Prefs.SetStringPref("fiddler.certmaker.bc.key", App.Configuration.UrlCapture.Key); FiddlerApplication.Prefs.SetStringPref("fiddler.certmaker.bc.cert", App.Configuration.UrlCapture.Cert); }} This is kind of a drag to do and not documented anywhere that I could find, so hopefully this will save you some grief if you want to work with the stock certificate logic that installs with FiddlerCore. MakeCert provides sticky Certificates and the same functionality as Fiddler But there’s actually an easier way. If you want to skip the above Fiddler preference configuration code in your application you can choose to distribute MakeCert.exe instead of certmaker.dll and bcmakecert.dll. When you use MakeCert.exe, the certificates settings are stored in Windows so they are available without any custom configuration inside of your application. It’s easier to integrate and as long as you run on Windows and you don’t need to support iOS or Android devices is simply easier to deal with. To integrate into your project, you can remove the reference to CertMaker.dll (and the BcMakeCert.dll assembly) from your project. Instead copy MakeCert.exe into your output folder. To make sure MakeCert.exe gets pushed out, include MakeCert.exe in your project and set the Build Action to None, and Copy to Output Directory to Copy if newer. Note that the CertMaker.dll reference in the project has been removed and on disk the files for Certmaker.dll, as well as the BCMakeCert.dll files on disk. Keep in mind that these DLLs are resources of the FiddlerCore NuGet package, so updating the package may end up pushing those files back into your project. Once MakeCert.exe is distributed FiddlerCore checks for it first before using the assemblies so as long as MakeCert.exe exists it’ll be used for certificate creation (at least on Windows). Summary FiddlerCore is a pretty sweet tool, and it’s absolutely awesome that we get to plug in most of the functionality of Fiddler right into our own applications. A few years back I tried to build this sort of functionality myself for an app and ended up giving up because it’s a big job to get HTTP right – especially if you need to support SSL. FiddlerCore now provides that functionality as a turnkey solution that can be plugged into your own apps easily. The only downside is FiddlerCore’s documentation for more advanced features like certificate installation which is pretty sketchy. While for the most part FiddlerCore’s feature set is easy to work with without any documentation, advanced features are often not intuitive to gleam by just using Intellisense or the FiddlerCore help file reference (which is not terribly useful). While Eric Lawrence is very responsive on his forum and on Twitter, there simply isn’t much useful documentation on Fiddler/FiddlerCore available online. If you run into trouble the forum is probably the first place to look and then ask a question if you can’t find the answer. The best documentation you can find is Eric’s Fiddler Book which covers a ton of functionality of Fiddler and FiddlerCore. The book is a great reference to Fiddler’s feature set as well as providing great insights into the HTTP protocol. The second half of the book that gets into the innards of HTTP is an excellent read for anybody who wants to know more about some of the more arcane aspects and special behaviors of HTTP – it’s well worth the read. While the book has tons of information in a very readable format, it’s unfortunately not a great reference as it’s hard to find things in the book and because it’s not available online you can’t electronically search for the great content in it. But it’s hard to complain about any of this given the obvious effort and love that’s gone into this awesome product for all of these years. A mighty big thanks to Eric Lawrence  for having created this useful tool that so many of us use all the time, and also to Telerik for picking up Fiddler/FiddlerCore and providing Eric the resources to support and improve this wonderful tool full time and keeping it free for all. Kudos! Resources FiddlerCore Download FiddlerCore NuGet Fiddler Capture Sample Form Fiddler Capture Form in West Wind WebSurge (GitHub) Eric Lawrence’s Fiddler Book© Rick Strahl, West Wind Technologies, 2005-2014Posted in .NET  HTTP   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

    Read the article

  • Dynamic connection for LINQ to SQL DataContext

    - by Steve Clements
    If for some reason you need to specify a specific connection string for a DataContext, you can of course pass the connection string when you initialise you DataContext object.  A common scenario could be a dev/test/stage/live connection string, but in my case its for either a live or archive database.   I however want the connection string to be handled by the DataContext, there are probably lots of different reasons someone would want to do this…but here are mine. I want the same connection string for all instances of DataContext, but I don’t know what it is yet! I prefer the clean code and ease of not using a constructor parameter. The refactoring of using a constructor parameter could be a nightmare.   So my approach is to create a new partial class for the DataContext and handle empty constructor in there. First from within the LINQ to SQL designer I changed the connection property to None.  This will remove the empty constructor code from the auto generated designer.cs file. Right click on the .dbml file, click View Code and a file and class is created for you! You’ll see the new class created in solutions explorer and the file will open. We are going to be playing with constructors so you need to add the inheritance from System.Data.Linq.DataContext public partial class DataClasses1DataContext : System.Data.Linq.DataContext    {    }   Add the empty constructor and I have added a property that will get my connection string, you will have whatever logic you need to decide and get the connection string you require.  In my case I will be hitting a database, but I have omitted that code. public partial class DataClasses1DataContext : System.Data.Linq.DataContext {    // Connection String Keys - stored in web.config    static string LiveConnectionStringKey = "LiveConnectionString";    static string ArchiveConnectionStringKey = "ArchiveConnectionString";      protected static string ConnectionString    {       get       {          if (DoIWantToUseTheLiveConnection) {             return global::System.Configuration.ConfigurationManager.ConnectionStrings[LiveConnectionStringKey].ConnectionString;          }          else {             return global::System.Configuration.ConfigurationManager.ConnectionStrings[ArchiveConnectionStringKey].ConnectionString;          }       }    }      public DataClasses1DataContext() :       base(ConnectionString, mappingSource)    {       OnCreated();    } }   Now when I new up my DataContext, I can just leave the constructor empty and my partial class will decide which one i need to use. Nice, clean code that can be easily refractored and tested.   Share this post :

    Read the article

  • ASP.NET GZip Encoding Caveats

    - by Rick Strahl
    GZip encoding in ASP.NET is pretty easy to accomplish using the built-in GZipStream and DeflateStream classes and applying them to the Response.Filter property.  While applying GZip and Deflate behavior is pretty easy there are a few caveats that you have watch out for as I found out today for myself with an application that was throwing up some garbage data. But before looking at caveats let’s review GZip implementation for ASP.NET. ASP.NET GZip/Deflate Basics Response filters basically are applied to the Response.OutputStream and transform it as data is written to it through the ASP.NET Response object. So a Response.Write eventually gets written into the output stream which if a filter is also written through the filter stream’s interface. To perform the actual GZip (and Deflate) encoding typically used by Web pages .NET includes the GZipStream and DeflateStream stream classes which can be readily assigned to the Repsonse.OutputStream. With these two stream classes in place it’s almost trivially easy to create a couple of reusable methods that allow you to compress your HTTP output. In my standard WebUtils utility class (from the West Wind West Wind Web Toolkit) created two static utility methods – IsGZipSupported and GZipEncodePage – that check whether the client supports GZip encoding and then actually encodes the current output (note that although the method includes ‘Page’ in its name this code will work with any ASP.NET output). /// <summary> /// Determines if GZip is supported /// </summary> /// <returns></returns> public static bool IsGZipSupported() { string AcceptEncoding = HttpContext.Current.Request.Headers["Accept-Encoding"]; if (!string.IsNullOrEmpty(AcceptEncoding) && (AcceptEncoding.Contains("gzip") || AcceptEncoding.Contains("deflate"))) return true; return false; } /// <summary> /// Sets up the current page or handler to use GZip through a Response.Filter /// IMPORTANT: /// You have to call this method before any output is generated! /// </summary> public static void GZipEncodePage() { HttpResponse Response = HttpContext.Current.Response; if (IsGZipSupported()) { string AcceptEncoding = HttpContext.Current.Request.Headers["Accept-Encoding"]; if (AcceptEncoding.Contains("deflate")) { Response.Filter = new System.IO.Compression.DeflateStream(Response.Filter, System.IO.Compression.CompressionMode.Compress); Response.Headers.Remove("Content-Encoding"); Response.AppendHeader("Content-Encoding", "deflate"); } else { Response.Filter = new System.IO.Compression.GZipStream(Response.Filter, System.IO.Compression.CompressionMode.Compress); Response.Headers.Remove("Content-Encoding"); Response.AppendHeader("Content-Encoding", "gzip"); } } } As you can see the actual assignment of the Filter is as simple as: Response.Filter = new DeflateStream(Response.Filter, System.IO.Compression.CompressionMode.Compress); which applies the filter to the OutputStream. You also need to ensure that your response reflects the new GZip or Deflate encoding and ensure that any pages that are cached in Proxy servers can differentiate between pages that were encoded with the various different encodings (or no encoding). To use this utility function now is trivially easy: In any ASP.NET code that wants to compress its Response output you simply use: protected void Page_Load(object sender, EventArgs e) { WebUtils.GZipEncodePage(); Entry = WebLogFactory.GetEntry(); var entries = Entry.GetLastEntries(App.Configuration.ShowEntryCount, "pk,Title,SafeTitle,Body,Entered,Feedback,Location,ShowTopAd", "TEntries"); if (entries == null) throw new ApplicationException("Couldn't load WebLog Entries: " + Entry.ErrorMessage); this.repEntries.DataSource = entries; this.repEntries.DataBind(); } Here I use an ASP.NET page, but the above WebUtils.GZipEncode() method call will work in any ASP.NET application type including HTTP Handlers. The only requirement is that the filter needs to be applied before any other output is sent to the OutputStream. For example, in my CallbackHandler service implementation by default output over a certain size is GZip encoded. The output that is generated is JSON or XML and if the output is over 5k in size I apply WebUtils.GZipEncode(): if (sbOutput.Length > GZIP_ENCODE_TRESHOLD) WebUtils.GZipEncodePage(); Response.ContentType = ControlResources.STR_JsonContentType; HttpContext.Current.Response.Write(sbOutput.ToString()); Ok, so you probably get the idea: Encoding GZip/Deflate content is pretty easy. Hold on there Hoss –Watch your Caching Or is it? There are a few caveats that you need to watch out for when dealing with GZip content. The fist issue is that you need to deal with the fact that some clients don’t support GZip or Deflate content. Most modern browsers support it, but if you have a programmatic Http client accessing your content GZip/Deflate support is by no means guaranteed. For example, WinInet Http clients don’t support GZip out of the box – it has to be explicitly implemented. Other low level HTTP clients on other platforms too don’t support GZip out of the box. The problem is that your application, your Web Server and Proxy Servers on the Internet might be caching your generated content. If you return content with GZip once and then again without, either caching is not applied or worse the wrong type of content is returned back to the client from a cache or proxy. The result is an unreadable response for *some clients* which is also very hard to debug and fix once in production. You already saw the issue of Proxy servers addressed in the GZipEncodePage() function: // Allow proxy servers to cache encoded and unencoded versions separately Response.AppendHeader("Vary", "Content-Encoding"); This ensures that any Proxy servers also check for the Content-Encoding HTTP Header to cache their content – not just the URL. The same thing applies if you do OutputCaching in your own ASP.NET code. If you generate output for GZip on an OutputCached page the GZipped content will be cached (either by ASP.NET’s cache or in some cases by the IIS Kernel Cache). But what if the next client doesn’t support GZip? She’ll get served a cached GZip page that won’t decode and she’ll get a page full of garbage. Wholly undesirable. To fix this you need to add some custom OutputCache rules by way of the GetVaryByCustom() HttpApplication method in your global_ASAX file: public override string GetVaryByCustomString(HttpContext context, string custom) { // Override Caching for compression if (custom == "GZIP") { string acceptEncoding = HttpContext.Current.Response.Headers["Content-Encoding"]; if (string.IsNullOrEmpty(acceptEncoding)) return ""; else if (acceptEncoding.Contains("gzip")) return "GZIP"; else if (acceptEncoding.Contains("deflate")) return "DEFLATE"; return ""; } return base.GetVaryByCustomString(context, custom); } In a page that use Output caching you then specify: <%@ OutputCache Duration="180" VaryByParam="none" VaryByCustom="GZIP" %> To use that custom rule. It’s all Fun and Games until ASP.NET throws an Error Ok, so you’re up and running with GZip, you have your caching squared away and your pages that you are applying it to are jamming along. Then BOOM, something strange happens and you get a lovely garbled page that look like this: Lovely isn’t it? What’s happened here is that I have WebUtils.GZipEncode() applied to my page, but there’s an error in the page. The error falls back to the ASP.NET error handler and the error handler removes all existing output (good) and removes all the custom HTTP headers I’ve set manually (usually good, but very bad here). Since I applied the Response.Filter (via GZipEncode) the output is now GZip encoded, but ASP.NET has removed my Content-Encoding header, so the browser receives the GZip encoded content without a notification that it is encoded as GZip. The result is binary output. Here’s what Fiddler says about the raw HTTP header output when an error occurs when GZip encoding was applied: HTTP/1.1 500 Internal Server Error Cache-Control: private Content-Type: text/html; charset=utf-8 Date: Sat, 30 Apr 2011 22:21:08 GMT Content-Length: 2138 Connection: close ?`I?%&/m?{J?J??t??` … binary output striped here Notice: no Content-Encoding header and that’s why we’re seeing this garbage. ASP.NET has stripped the Content-Encoding header but left our filter intact. So how do we fix this? In my applications I typically have a global Application_Error handler set up and in this case I’ve been using that. One thing that you can do in the Application_Error handler is explicitly clear out the Response.Filter and set it to null at the top: protected void Application_Error(object sender, EventArgs e) { // Remove any special filtering especially GZip filtering Response.Filter = null; … } And voila I get my Yellow Screen of Death or my custom generated error output back via uncompressed content. BTW, the same is true for Page level errors handled in Page_Error or ASP.NET MVC Error handling methods in a controller. Another and possibly even better solution is to check whether a filter is attached just before the headers are sent to the client as pointed out by Adam Schroeder in the comments: protected void Application_PreSendRequestHeaders() { // ensure that if GZip/Deflate Encoding is applied that headers are set // also works when error occurs if filters are still active HttpResponse response = HttpContext.Current.Response; if (response.Filter is GZipStream && response.Headers["Content-encoding"] != "gzip") response.AppendHeader("Content-encoding", "gzip"); else if (response.Filter is DeflateStream && response.Headers["Content-encoding"] != "deflate") response.AppendHeader("Content-encoding", "deflate"); } This uses the Application_PreSendRequestHeaders() pipeline event to check for compression encoding in a filter and adjusts the content accordingly. This is actually a better solution since this is generic – it’ll work regardless of how the content is cleaned up. For example, an error Response.Redirect() or short error display might get changed and the filter not cleared and this code actually handles that. Sweet, thanks Adam. It’s unfortunate that ASP.NET doesn’t natively clear out Response.Filters when an error occurs just as it clears the Response and Headers. I can’t see where leaving a Filter in place in an error situation would make any sense, but hey - this is what it is and it’s easy enough to fix as long as you know where to look. Riiiight! IIS and GZip I should also mention that IIS 7 includes good support for compression natively. If you can defer encoding to let IIS perform it for you rather than doing it in your code by all means you should do it! Especially any static or semi-dynamic content that can be made static should be using IIS built-in compression. Dynamic caching is also supported but is a bit more tricky to judge in terms of performance and footprint. John Forsyth has a great article on the benefits and drawbacks of IIS 7 compression which gives some detailed performance comparisons and impact reviews. I’ll post another entry next with some more info on IIS compression since information on it seems to be a bit hard to come by. Related Content Built-in GZip/Deflate Compression in IIS 7.x HttpWebRequest and GZip Responses © Rick Strahl, West Wind Technologies, 2005-2011Posted in ASP.NET   IIS7  

    Read the article

  • ASP.NET MVC ModelCopier

    - by shiju
     In my earlier post ViewModel patten and AutoMapper in ASP.NET MVC application, We have discussed the need for  View Model objects and how to map values between View Model objects and Domain model objects using AutoMapper. ASP.NET MVC futures assembly provides a static class ModelCopier that can also use for copying values between View Model objects and Domain model objects. ModelCopier class has two static methods - CopyCollection and CopyModel.CopyCollection method would copy values between two collection objects and CopyModel would copy values between two model objects. <PRE class="c#" name="code"> var expense=new Expense(); ModelCopier.CopyModel(expenseViewModel, expense);</PRE>The above code copying values from expenseViewModel object to  expense object.                For simple mapping between model objects, you can use ModelCopier but for complex scenarios, I highly recommending to using AutoMapper for mapping between model objects.

    Read the article

  • Java Logger API

    - by Koppar
    This is a more like a tip rather than technical write up and serves as a quick intro for newbies. The logger API helps to diagnose application level or JDK level issues at runtime. There are 7 levels which decide the detailing in logging (SEVERE, WARNING, INFO, CONFIG, FINE, FINER, FINEST). Its best to start with highest level and as we narrow down, use more detailed logging for a specific area. SEVERE is the highest and FINEST is the lowest. This may not make sense until we understand some jargon. The Logger class provides the ability to stream messages to an output stream in a format that can be controlled by the user. What this translates to is, I can create a logger with this simple invocation and use it add debug messages in my class: import java.util.logging.*; private static final Logger focusLog = Logger.getLogger("java.awt.focus.KeyboardFocusManager"); if (focusLog.isLoggable(Level.FINEST)) { focusLog.log(Level.FINEST, "Calling peer setCurrentFocusOwner}); LogManager acts like a book keeper and all the getLogger calls are forwarded to LogManager. The LogManager itself is a singleton class object which gets statically initialized on JVM start up. More on this later. If there is no existing logger with the given name, a new one is created. If there is one (and not yet GC’ed), then the existing Logger object is returned. By default, a root logger is created on JVM start up. All anonymous loggers are made as the children of the root logger. Named loggers have the hierarchy as per their name resolutions. Eg: java.awt.focus is the parent logger for java.awt.focus.KeyboardFocusManager etc. Before logging any message, the logger checks for the log level specified. If null is specified, the log level of the parent logger will be set. However, if the log level is off, no log messages would be written, irrespective of the parent’s log level. All the messages that are posted to the Logger are handled as a LogRecord object.i.e. FocusLog.log would create a new LogRecord object with the log level and message as its data members). The level of logging and thread number are also tracked. LogRecord is passed on to all the registered Handlers. Handler is basically a means to output the messages. The output may be redirected to either a log file or console or a network logging service. The Handler classes use the LogManager properties to set filters and formatters. During initialization or JVM start up, LogManager looks for logging.properties file in jre/lib and sets the properties if the file is provided. An alternate location for properties file can also be specified by setting java.util.logging.config.file system property. This can be set in Java Control Panel ? Java ? Runtime parameters as -Djava.util.logging.config.file = <mylogfile> or passed as a command line parameter java -Djava.util.logging.config.file = C:/Sunita/myLog The redirection of logging depends on what is specified rather registered as a handler with JVM in the properties file. java.util.logging.ConsoleHandler sends the output to system.err and java.util.logging.FileHandler sends the output to file. File name of the log file can also be specified. If you prefer XML format output, in the configuration file, set java.util.logging.FileHandler.formatter = java.util.logging.XMLFormatter and if you prefer simple text, set set java.util.logging.FileHandler.formatter =java.util.logging.SimpleFormatter Below is the default logging Configuration file: ############################################################ # Default Logging Configuration File # You can use a different file by specifying a filename # with the java.util.logging.config.file system property. # For example java -Djava.util.logging.config.file=myfile ############################################################ ############################################################ # Global properties ############################################################ # "handlers" specifies a comma separated list of log Handler # classes. These handlers will be installed during VM startup. # Note that these classes must be on the system classpath. # By default we only configure a ConsoleHandler, which will only # show messages at the INFO and above levels. handlers= java.util.logging.ConsoleHandler # To also add the FileHandler, use the following line instead. #handlers= java.util.logging.FileHandler, java.util.logging.ConsoleHandler # Default global logging level. # This specifies which kinds of events are logged across # all loggers. For any given facility this global level # can be overriden by a facility specific level # Note that the ConsoleHandler also has a separate level # setting to limit messages printed to the console. .level= INFO ############################################################ # Handler specific properties. # Describes specific configuration info for Handlers. ############################################################ # default file output is in user's home directory. java.util.logging.FileHandler.pattern = %h/java%u.log java.util.logging.FileHandler.limit = 50000 java.util.logging.FileHandler.count = 1 java.util.logging.FileHandler.formatter = java.util.logging.XMLFormatter # Limit the message that are printed on the console to INFO and above. java.util.logging.ConsoleHandler.level = INFO java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter ############################################################ # Facility specific properties. # Provides extra control for each logger. ############################################################ # For example, set the com.xyz.foo logger to only log SEVERE # messages: com.xyz.foo.level = SEVERE Since I primarily use this method to track focus issues, here is how I get detailed awt focus related logging. Just set the logger name to java.awt.focus.level=FINEST and change the default log level to FINEST. Below is a basic sample program. The sample programs are from http://www2.cs.uic.edu/~sloan/CLASSES/java/ and have been modified to illustrate the logging API. By changing the .level property in the logging.properties file, one can control the output written to the logs. To play around with the example, try changing the levels in the logging.properties file and notice the difference in messages going to the log file. Example --------KeyboardReader.java------------------------------------------------------------------------------------- import java.io.*; import java.util.*; import java.util.logging.*; public class KeyboardReader { private static final Logger mylog = Logger.getLogger("samples.input"); public static void main (String[] args) throws java.io.IOException { String s1; String s2; double num1, num2, product; // set up the buffered reader to read from the keyboard BufferedReader br = new BufferedReader (new InputStreamReader (System.in)); System.out.println ("Enter a line of input"); s1 = br.readLine(); if (mylog.isLoggable(Level.SEVERE)) { mylog.log (Level.SEVERE,"The line entered is " + s1); } if (mylog.isLoggable(Level.INFO)) { mylog.log (Level.INFO,"The line has " + s1.length() + " characters"); } if (mylog.isLoggable(Level.FINE)) { mylog.log (Level.FINE,"Breaking the line into tokens we get:"); } int numTokens = 0; StringTokenizer st = new StringTokenizer (s1); while (st.hasMoreTokens()) { s2 = st.nextToken(); numTokens++; if (mylog.isLoggable(Level.FINEST)) { mylog.log (Level.FINEST, " Token " + numTokens + " is: " + s2); } } } } ----------MyFileReader.java---------------------------------------------------------------------------------------- import java.io.*; import java.util.*; import java.util.logging.*; public class MyFileReader extends KeyboardReader { private static final Logger mylog = Logger.getLogger("samples.input.file"); public static void main (String[] args) throws java.io.IOException { String s1; String s2; // set up the buffered reader to read from the keyboard BufferedReader br = new BufferedReader (new FileReader ("MyFileReader.txt")); s1 = br.readLine(); if (mylog.isLoggable(Level.SEVERE)) { mylog.log (Level.SEVERE,"ATTN The line is " + s1); } if (mylog.isLoggable(Level.INFO)) { mylog.log (Level.INFO, "The line has " + s1.length() + " characters"); } if (mylog.isLoggable(Level.FINE)) { mylog.log (Level.FINE,"Breaking the line into tokens we get:"); } int numTokens = 0; StringTokenizer st = new StringTokenizer (s1); while (st.hasMoreTokens()) { s2 = st.nextToken(); numTokens++; if (mylog.isLoggable(Level.FINEST)) { mylog.log (Level.FINEST,"Breaking the line into tokens we get:"); mylog.log (Level.FINEST," Token " + numTokens + " is: " + s2); } } //end of while } // end of main } // end of class ----------MyFileReader.txt------------------------------------------------------------------------------------------ My first logging example -------logging.properties------------------------------------------------------------------------------------------- handlers= java.util.logging.ConsoleHandler, java.util.logging.FileHandler .level= FINEST java.util.logging.FileHandler.pattern = java%u.log java.util.logging.FileHandler.limit = 50000 java.util.logging.FileHandler.count = 1 java.util.logging.FileHandler.formatter = java.util.logging.SimpleFormatter java.util.logging.ConsoleHandler.level = FINEST java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter java.awt.focus.level=ALL ------Output log------------------------------------------------------------------------------------------- May 21, 2012 11:44:55 AM MyFileReader main SEVERE: ATTN The line is My first logging example May 21, 2012 11:44:55 AM MyFileReader main INFO: The line has 24 characters May 21, 2012 11:44:55 AM MyFileReader main FINE: Breaking the line into tokens we get: May 21, 2012 11:44:55 AM MyFileReader main FINEST: Breaking the line into tokens we get: May 21, 2012 11:44:55 AM MyFileReader main FINEST: Token 1 is: My May 21, 2012 11:44:55 AM MyFileReader main FINEST: Breaking the line into tokens we get: May 21, 2012 11:44:55 AM MyFileReader main FINEST: Token 2 is: first May 21, 2012 11:44:55 AM MyFileReader main FINEST: Breaking the line into tokens we get: May 21, 2012 11:44:55 AM MyFileReader main FINEST: Token 3 is: logging May 21, 2012 11:44:55 AM MyFileReader main FINEST: Breaking the line into tokens we get: May 21, 2012 11:44:55 AM MyFileReader main FINEST: Token 4 is: example Invocation command: "C:\Program Files (x86)\Java\jdk1.6.0_29\bin\java.exe" -Djava.util.logging.config.file=logging.properties MyFileReader References Further technical details are available here: http://docs.oracle.com/javase/1.4.2/docs/guide/util/logging/overview.html#1.0 http://docs.oracle.com/javase/1.4.2/docs/api/java/util/logging/package-summary.html http://www2.cs.uic.edu/~sloan/CLASSES/java/

    Read the article

  • The Incremental Architect&rsquo;s Napkin - #5 - Design functions for extensibility and readability

    - by Ralf Westphal
    Originally posted on: http://geekswithblogs.net/theArchitectsNapkin/archive/2014/08/24/the-incremental-architectrsquos-napkin---5---design-functions-for.aspx The functionality of programs is entered via Entry Points. So what we´re talking about when designing software is a bunch of functions handling the requests represented by and flowing in through those Entry Points. Designing software thus consists of at least three phases: Analyzing the requirements to find the Entry Points and their signatures Designing the functionality to be executed when those Entry Points get triggered Implementing the functionality according to the design aka coding I presume, you´re familiar with phase 1 in some way. And I guess you´re proficient in implementing functionality in some programming language. But in my experience developers in general are not experienced in going through an explicit phase 2. “Designing functionality? What´s that supposed to mean?” you might already have thought. Here´s my definition: To design functionality (or functional design for short) means thinking about… well, functions. You find a solution for what´s supposed to happen when an Entry Point gets triggered in terms of functions. A conceptual solution that is, because those functions only exist in your head (or on paper) during this phase. But you may have guess that, because it´s “design” not “coding”. And here is, what functional design is not: It´s not about logic. Logic is expressions (e.g. +, -, && etc.) and control statements (e.g. if, switch, for, while etc.). Also I consider calling external APIs as logic. It´s equally basic. It´s what code needs to do in order to deliver some functionality or quality. Logic is what´s doing that needs to be done by software. Transformations are either done through expressions or API-calls. And then there is alternative control flow depending on the result of some expression. Basically it´s just jumps in Assembler, sometimes to go forward (if, switch), sometimes to go backward (for, while, do). But calling your own function is not logic. It´s not necessary to produce any outcome. Functionality is not enhanced by adding functions (subroutine calls) to your code. Nor is quality increased by adding functions. No performance gain, no higher scalability etc. through functions. Functions are not relevant to functionality. Strange, isn´t it. What they are important for is security of investment. By introducing functions into our code we can become more productive (re-use) and can increase evolvability (higher unterstandability, easier to keep code consistent). That´s no small feat, however. Evolvable code can hardly be overestimated. That´s why to me functional design is so important. It´s at the core of software development. To sum this up: Functional design is on a level of abstraction above (!) logical design or algorithmic design. Functional design is only done until you get to a point where each function is so simple you are very confident you can easily code it. Functional design an logical design (which mostly is coding, but can also be done using pseudo code or flow charts) are complementary. Software needs both. If you start coding right away you end up in a tangled mess very quickly. Then you need back out through refactoring. Functional design on the other hand is bloodless without actual code. It´s just a theory with no experiments to prove it. But how to do functional design? An example of functional design Let´s assume a program to de-duplicate strings. The user enters a number of strings separated by commas, e.g. a, b, a, c, d, b, e, c, a. And the program is supposed to clear this list of all doubles, e.g. a, b, c, d, e. There is only one Entry Point to this program: the user triggers the de-duplication by starting the program with the string list on the command line C:\>deduplicate "a, b, a, c, d, b, e, c, a" a, b, c, d, e …or by clicking on a GUI button. This leads to the Entry Point function to get called. It´s the program´s main function in case of the batch version or a button click event handler in the GUI version. That´s the physical Entry Point so to speak. It´s inevitable. What then happens is a three step process: Transform the input data from the user into a request. Call the request handler. Transform the output of the request handler into a tangible result for the user. Or to phrase it a bit more generally: Accept input. Transform input into output. Present output. This does not mean any of these steps requires a lot of effort. Maybe it´s just one line of code to accomplish it. Nevertheless it´s a distinct step in doing the processing behind an Entry Point. Call it an aspect or a responsibility - and you will realize it most likely deserves a function of its own to satisfy the Single Responsibility Principle (SRP). Interestingly the above list of steps is already functional design. There is no logic, but nevertheless the solution is described - albeit on a higher level of abstraction than you might have done yourself. But it´s still on a meta-level. The application to the domain at hand is easy, though: Accept string list from command line De-duplicate Present de-duplicated strings on standard output And this concrete list of processing steps can easily be transformed into code:static void Main(string[] args) { var input = Accept_string_list(args); var output = Deduplicate(input); Present_deduplicated_string_list(output); } Instead of a big problem there are three much smaller problems now. If you think each of those is trivial to implement, then go for it. You can stop the functional design at this point. But maybe, just maybe, you´re not so sure how to go about with the de-duplication for example. Then just implement what´s easy right now, e.g.private static string Accept_string_list(string[] args) { return args[0]; } private static void Present_deduplicated_string_list( string[] output) { var line = string.Join(", ", output); Console.WriteLine(line); } Accept_string_list() contains logic in the form of an API-call. Present_deduplicated_string_list() contains logic in the form of an expression and an API-call. And then repeat the functional design for the remaining processing step. What´s left is the domain logic: de-duplicating a list of strings. How should that be done? Without any logic at our disposal during functional design you´re left with just functions. So which functions could make up the de-duplication? Here´s a suggestion: De-duplicate Parse the input string into a true list of strings. Register each string in a dictionary/map/set. That way duplicates get cast away. Transform the data structure into a list of unique strings. Processing step 2 obviously was the core of the solution. That´s where real creativity was needed. That´s the core of the domain. But now after this refinement the implementation of each step is easy again:private static string[] Parse_string_list(string input) { return input.Split(',') .Select(s => s.Trim()) .ToArray(); } private static Dictionary<string,object> Compile_unique_strings(string[] strings) { return strings.Aggregate( new Dictionary<string, object>(), (agg, s) => { agg[s] = null; return agg; }); } private static string[] Serialize_unique_strings( Dictionary<string,object> dict) { return dict.Keys.ToArray(); } With these three additional functions Main() now looks like this:static void Main(string[] args) { var input = Accept_string_list(args); var strings = Parse_string_list(input); var dict = Compile_unique_strings(strings); var output = Serialize_unique_strings(dict); Present_deduplicated_string_list(output); } I think that´s very understandable code: just read it from top to bottom and you know how the solution to the problem works. It´s a mirror image of the initial design: Accept string list from command line Parse the input string into a true list of strings. Register each string in a dictionary/map/set. That way duplicates get cast away. Transform the data structure into a list of unique strings. Present de-duplicated strings on standard output You can even re-generate the design by just looking at the code. Code and functional design thus are always in sync - if you follow some simple rules. But about that later. And as a bonus: all the functions making up the process are small - which means easy to understand, too. So much for an initial concrete example. Now it´s time for some theory. Because there is method to this madness ;-) The above has only scratched the surface. Introducing Flow Design Functional design starts with a given function, the Entry Point. Its goal is to describe the behavior of the program when the Entry Point is triggered using a process, not an algorithm. An algorithm consists of logic, a process on the other hand consists just of steps or stages. Each processing step transforms input into output or a side effect. Also it might access resources, e.g. a printer, a database, or just memory. Processing steps thus can rely on state of some sort. This is different from Functional Programming, where functions are supposed to not be stateful and not cause side effects.[1] In its simplest form a process can be written as a bullet point list of steps, e.g. Get data from user Output result to user Transform data Parse data Map result for output Such a compilation of steps - possibly on different levels of abstraction - often is the first artifact of functional design. It can be generated by a team in an initial design brainstorming. Next comes ordering the steps. What should happen first, what next etc.? Get data from user Parse data Transform data Map result for output Output result to user That´s great for a start into functional design. It´s better than starting to code right away on a given function using TDD. Please get me right: TDD is a valuable practice. But it can be unnecessarily hard if the scope of a functionn is too large. But how do you know beforehand without investing some thinking? And how to do this thinking in a systematic fashion? My recommendation: For any given function you´re supposed to implement first do a functional design. Then, once you´re confident you know the processing steps - which are pretty small - refine and code them using TDD. You´ll see that´s much, much easier - and leads to cleaner code right away. For more information on this approach I call “Informed TDD” read my book of the same title. Thinking before coding is smart. And writing down the solution as a bunch of functions possibly is the simplest thing you can do, I´d say. It´s more according to the KISS (Keep It Simple, Stupid) principle than returning constants or other trivial stuff TDD development often is started with. So far so good. A simple ordered list of processing steps will do to start with functional design. As shown in the above example such steps can easily be translated into functions. Moving from design to coding thus is simple. However, such a list does not scale. Processing is not always that simple to be captured in a list. And then the list is just text. Again. Like code. That means the design is lacking visuality. Textual representations need more parsing by your brain than visual representations. Plus they are limited in their “dimensionality”: text just has one dimension, it´s sequential. Alternatives and parallelism are hard to encode in text. In addition the functional design using numbered lists lacks data. It´s not visible what´s the input, output, and state of the processing steps. That´s why functional design should be done using a lightweight visual notation. No tool is necessary to draw such designs. Use pen and paper; a flipchart, a whiteboard, or even a napkin is sufficient. Visualizing processes The building block of the functional design notation is a functional unit. I mostly draw it like this: Something is done, it´s clear what goes in, it´s clear what comes out, and it´s clear what the processing step requires in terms of state or hardware. Whenever input flows into a functional unit it gets processed and output is produced and/or a side effect occurs. Flowing data is the driver of something happening. That´s why I call this approach to functional design Flow Design. It´s about data flow instead of control flow. Control flow like in algorithms is of no concern to functional design. Thinking about control flow simply is too low level. Once you start with control flow you easily get bogged down by tons of details. That´s what you want to avoid during design. Design is supposed to be quick, broad brush, abstract. It should give overview. But what about all the details? As Robert C. Martin rightly said: “Programming is abot detail”. Detail is a matter of code. Once you start coding the processing steps you designed you can worry about all the detail you want. Functional design does not eliminate all the nitty gritty. It just postpones tackling them. To me that´s also an example of the SRP. Function design has the responsibility to come up with a solution to a problem posed by a single function (Entry Point). And later coding has the responsibility to implement the solution down to the last detail (i.e. statement, API-call). TDD unfortunately mixes both responsibilities. It´s just coding - and thereby trying to find detailed implementations (green phase) plus getting the design right (refactoring). To me that´s one reason why TDD has failed to deliver on its promise for many developers. Using functional units as building blocks of functional design processes can be depicted very easily. Here´s the initial process for the example problem: For each processing step draw a functional unit and label it. Choose a verb or an “action phrase” as a label, not a noun. Functional design is about activities, not state or structure. Then make the output of an upstream step the input of a downstream step. Finally think about the data that should flow between the functional units. Write the data above the arrows connecting the functional units in the direction of the data flow. Enclose the data description in brackets. That way you can clearly see if all flows have already been specified. Empty brackets mean “no data is flowing”, but nevertheless a signal is sent. A name like “list” or “strings” in brackets describes the data content. Use lower case labels for that purpose. A name starting with an upper case letter like “String” or “Customer” on the other hand signifies a data type. If you like, you also can combine descriptions with data types by separating them with a colon, e.g. (list:string) or (strings:string[]). But these are just suggestions from my practice with Flow Design. You can do it differently, if you like. Just be sure to be consistent. Flows wired-up in this manner I call one-dimensional (1D). Each functional unit just has one input and/or one output. A functional unit without an output is possible. It´s like a black hole sucking up input without producing any output. Instead it produces side effects. A functional unit without an input, though, does make much sense. When should it start to work? What´s the trigger? That´s why in the above process even the first processing step has an input. If you like, view such 1D-flows as pipelines. Data is flowing through them from left to right. But as you can see, it´s not always the same data. It get´s transformed along its passage: (args) becomes a (list) which is turned into (strings). The Principle of Mutual Oblivion A very characteristic trait of flows put together from function units is: no functional units knows another one. They are all completely independent of each other. Functional units don´t know where their input is coming from (or even when it´s gonna arrive). They just specify a range of values they can process. And they promise a certain behavior upon input arriving. Also they don´t know where their output is going. They just produce it in their own time independent of other functional units. That means at least conceptually all functional units work in parallel. Functional units don´t know their “deployment context”. They now nothing about the overall flow they are place in. They are just consuming input from some upstream, and producing output for some downstream. That makes functional units very easy to test. At least as long as they don´t depend on state or resources. I call this the Principle of Mutual Oblivion (PoMO). Functional units are oblivious of others as well as an overall context/purpose. They are just parts of a whole focused on a single responsibility. How the whole is built, how a larger goal is achieved, is of no concern to the single functional units. By building software in such a manner, functional design interestingly follows nature. Nature´s building blocks for organisms also follow the PoMO. The cells forming your body do not know each other. Take a nerve cell “controlling” a muscle cell for example:[2] The nerve cell does not know anything about muscle cells, let alone the specific muscel cell it is “attached to”. Likewise the muscle cell does not know anything about nerve cells, let a lone a specific nerve cell “attached to” it. Saying “the nerve cell is controlling the muscle cell” thus only makes sense when viewing both from the outside. “Control” is a concept of the whole, not of its parts. Control is created by wiring-up parts in a certain way. Both cells are mutually oblivious. Both just follow a contract. One produces Acetylcholine (ACh) as output, the other consumes ACh as input. Where the ACh is going, where it´s coming from neither cell cares about. Million years of evolution have led to this kind of division of labor. And million years of evolution have produced organism designs (DNA) which lead to the production of these different cell types (and many others) and also to their co-location. The result: the overall behavior of an organism. How and why this happened in nature is a mystery. For our software, though, it´s clear: functional and quality requirements needs to be fulfilled. So we as developers have to become “intelligent designers” of “software cells” which we put together to form a “software organism” which responds in satisfying ways to triggers from it´s environment. My bet is: If nature gets complex organisms working by following the PoMO, who are we to not apply this recipe for success to our much simpler “machines”? So my rule is: Wherever there is functionality to be delivered, because there is a clear Entry Point into software, design the functionality like nature would do it. Build it from mutually oblivious functional units. That´s what Flow Design is about. In that way it´s even universal, I´d say. Its notation can also be applied to biology: Never mind labeling the functional units with nouns. That´s ok in Flow Design. You´ll do that occassionally for functional units on a higher level of abstraction or when their purpose is close to hardware. Getting a cockroach to roam your bedroom takes 1,000,000 nerve cells (neurons). Getting the de-duplication program to do its job just takes 5 “software cells” (functional units). Both, though, follow the same basic principle. Translating functional units into code Moving from functional design to code is no rocket science. In fact it´s straightforward. There are two simple rules: Translate an input port to a function. Translate an output port either to a return statement in that function or to a function pointer visible to that function. The simplest translation of a functional unit is a function. That´s what you saw in the above example. Functions are mutually oblivious. That why Functional Programming likes them so much. It makes them composable. Which is the reason, nature works according to the PoMO. Let´s be clear about one thing: There is no dependency injection in nature. For all of an organism´s complexity no DI container is used. Behavior is the result of smooth cooperation between mutually oblivious building blocks. Functions will often be the adequate translation for the functional units in your designs. But not always. Take for example the case, where a processing step should not always produce an output. Maybe the purpose is to filter input. Here the functional unit consumes words and produces words. But it does not pass along every word flowing in. Some words are swallowed. Think of a spell checker. It probably should not check acronyms for correctness. There are too many of them. Or words with no more than two letters. Such words are called “stop words”. In the above picture the optionality of the output is signified by the astrisk outside the brackets. It means: Any number of (word) data items can flow from the functional unit for each input data item. It might be none or one or even more. This I call a stream of data. Such behavior cannot be translated into a function where output is generated with return. Because a function always needs to return a value. So the output port is translated into a function pointer or continuation which gets passed to the subroutine when called:[3]void filter_stop_words( string word, Action<string> onNoStopWord) { if (...check if not a stop word...) onNoStopWord(word); } If you want to be nitpicky you might call such a function pointer parameter an injection. And technically you´re right. Conceptually, though, it´s not an injection. Because the subroutine is not functionally dependent on the continuation. Firstly continuations are procedures, i.e. subroutines without a return type. Remember: Flow Design is about unidirectional data flow. Secondly the name of the formal parameter is chosen in a way as to not assume anything about downstream processing steps. onNoStopWord describes a situation (or event) within the functional unit only. Translating output ports into function pointers helps keeping functional units mutually oblivious in cases where output is optional or produced asynchronically. Either pass the function pointer to the function upon call. Or make it global by putting it on the encompassing class. Then it´s called an event. In C# that´s even an explicit feature.class Filter { public void filter_stop_words( string word) { if (...check if not a stop word...) onNoStopWord(word); } public event Action<string> onNoStopWord; } When to use a continuation and when to use an event dependens on how a functional unit is used in flows and how it´s packed together with others into classes. You´ll see examples further down the Flow Design road. Another example of 1D functional design Let´s see Flow Design once more in action using the visual notation. How about the famous word wrap kata? Robert C. Martin has posted a much cited solution including an extensive reasoning behind his TDD approach. So maybe you want to compare it to Flow Design. The function signature given is:string WordWrap(string text, int maxLineLength) {...} That´s not an Entry Point since we don´t see an application with an environment and users. Nevertheless it´s a function which is supposed to provide a certain functionality. The text passed in has to be reformatted. The input is a single line of arbitrary length consisting of words separated by spaces. The output should consist of one or more lines of a maximum length specified. If a word is longer than a the maximum line length it can be split in multiple parts each fitting in a line. Flow Design Let´s start by brainstorming the process to accomplish the feat of reformatting the text. What´s needed? Words need to be assembled into lines Words need to be extracted from the input text The resulting lines need to be assembled into the output text Words too long to fit in a line need to be split Does sound about right? I guess so. And it shows a kind of priority. Long words are a special case. So maybe there is a hint for an incremental design here. First let´s tackle “average words” (words not longer than a line). Here´s the Flow Design for this increment: The the first three bullet points turned into functional units with explicit data added. As the signature requires a text is transformed into another text. See the input of the first functional unit and the output of the last functional unit. In between no text flows, but words and lines. That´s good to see because thereby the domain is clearly represented in the design. The requirements are talking about words and lines and here they are. But note the asterisk! It´s not outside the brackets but inside. That means it´s not a stream of words or lines, but lists or sequences. For each text a sequence of words is output. For each sequence of words a sequence of lines is produced. The asterisk is used to abstract from the concrete implementation. Like with streams. Whether the list of words gets implemented as an array or an IEnumerable is not important during design. It´s an implementation detail. Does any processing step require further refinement? I don´t think so. They all look pretty “atomic” to me. And if not… I can always backtrack and refine a process step using functional design later once I´ve gained more insight into a sub-problem. Implementation The implementation is straightforward as you can imagine. The processing steps can all be translated into functions. Each can be tested easily and separately. Each has a focused responsibility. And the process flow becomes just a sequence of function calls: Easy to understand. It clearly states how word wrapping works - on a high level of abstraction. And it´s easy to evolve as you´ll see. Flow Design - Increment 2 So far only texts consisting of “average words” are wrapped correctly. Words not fitting in a line will result in lines too long. Wrapping long words is a feature of the requested functionality. Whether it´s there or not makes a difference to the user. To quickly get feedback I decided to first implement a solution without this feature. But now it´s time to add it to deliver the full scope. Fortunately Flow Design automatically leads to code following the Open Closed Principle (OCP). It´s easy to extend it - instead of changing well tested code. How´s that possible? Flow Design allows for extension of functionality by inserting functional units into the flow. That way existing functional units need not be changed. The data flow arrow between functional units is a natural extension point. No need to resort to the Strategy Pattern. No need to think ahead where extions might need to be made in the future. I just “phase in” the remaining processing step: Since neither Extract words nor Reformat know of their environment neither needs to be touched due to the “detour”. The new processing step accepts the output of the existing upstream step and produces data compatible with the existing downstream step. Implementation - Increment 2 A trivial implementation checking the assumption if this works does not do anything to split long words. The input is just passed on: Note how clean WordWrap() stays. The solution is easy to understand. A developer looking at this code sometime in the future, when a new feature needs to be build in, quickly sees how long words are dealt with. Compare this to Robert C. Martin´s solution:[4] How does this solution handle long words? Long words are not even part of the domain language present in the code. At least I need considerable time to understand the approach. Admittedly the Flow Design solution with the full implementation of long word splitting is longer than Robert C. Martin´s. At least it seems. Because his solution does not cover all the “word wrap situations” the Flow Design solution handles. Some lines would need to be added to be on par, I guess. But even then… Is a difference in LOC that important as long as it´s in the same ball park? I value understandability and openness for extension higher than saving on the last line of code. Simplicity is not just less code, it´s also clarity in design. But don´t take my word for it. Try Flow Design on larger problems and compare for yourself. What´s the easier, more straightforward way to clean code? And keep in mind: You ain´t seen all yet ;-) There´s more to Flow Design than described in this chapter. In closing I hope I was able to give you a impression of functional design that makes you hungry for more. To me it´s an inevitable step in software development. Jumping from requirements to code does not scale. And it leads to dirty code all to quickly. Some thought should be invested first. Where there is a clear Entry Point visible, it´s functionality should be designed using data flows. Because with data flows abstraction is possible. For more background on why that´s necessary read my blog article here. For now let me point out to you - if you haven´t already noticed - that Flow Design is a general purpose declarative language. It´s “programming by intention” (Shalloway et al.). Just write down how you think the solution should work on a high level of abstraction. This breaks down a large problem in smaller problems. And by following the PoMO the solutions to those smaller problems are independent of each other. So they are easy to test. Or you could even think about getting them implemented in parallel by different team members. Flow Design not only increases evolvability, but also helps becoming more productive. All team members can participate in functional design. This goes beyon collective code ownership. We´re talking collective design/architecture ownership. Because with Flow Design there is a common visual language to talk about functional design - which is the foundation for all other design activities.   PS: If you like what you read, consider getting my ebook “The Incremental Architekt´s Napkin”. It´s where I compile all the articles in this series for easier reading. I like the strictness of Function Programming - but I also find it quite hard to live by. And it certainly is not what millions of programmers are used to. Also to me it seems, the real world is full of state and side effects. So why give them such a bad image? That´s why functional design takes a more pragmatic approach. State and side effects are ok for processing steps - but be sure to follow the SRP. Don´t put too much of it into a single processing step. ? Image taken from www.physioweb.org ? My code samples are written in C#. C# sports typed function pointers called delegates. Action is such a function pointer type matching functions with signature void someName(T t). Other languages provide similar ways to work with functions as first class citizens - even Java now in version 8. I trust you find a way to map this detail of my translation to your favorite programming language. I know it works for Java, C++, Ruby, JavaScript, Python, Go. And if you´re using a Functional Programming language it´s of course a no brainer. ? Taken from his blog post “The Craftsman 62, The Dark Path”. ?

    Read the article

< Previous Page | 144 145 146 147 148 149 150 151 152 153 154 155  | Next Page >