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• Best suited tool to document message processing done in C written program

  - by user3494614

  I am relatively new to UML and it's seems to be very vast I have a small program which basically receives messages on socket and then depending upon message ID embedded as first byte of message it processes the buffer. There are around 5 different message ID which it processes and communicates on another socket and has around 8 major functions. So program in short is like this. I am not pasting entire .c file or main function but just giving some bits and pieces of it so that to get idea of program flow. int main(int argc, char** argv) { register_shared_mem(); listen(); while(get_next_message(buffer)) { switch((msg)(buffer)->id) { case TYPE1: process1(); answer(); ..... } } } I want to document this is pictorial way like for Message type 1 it calls this function which calls another and which calls another. Please let me know any open source tool which will allow me to quickly draw such kind of UML or sequence diagram and will also allow me to write brief description of what each function does? Thanks In Advance

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• Applying powershell outside IT Management.

  - by Tormod

  Hi. We have a flexible process control system by which automation engineers configure up large application comprising thousands of small logical units that are parameterized and integrated into the control flow. There are many tasks that are repetitive on the granular level, and there are a multitude of proprietary productivity tools that have been made to meet this demand. We have different business segments, and the automation engineers vary across the board in skill sets and interests. Fancy GUI and usability versus flexibility is a common discussion. At first glance, powershell seems to be a sensible platform to implement such tooling and which also would be a advantageous cross-over skill to manage the IT aspects of the system setup and deployment as a whole. This should allow the script savvy their desired flexibility (they are already a scripting crowd) and the GUI dependant could still get their desired GUI underpinned by powershell. But I can't seem to find many people/groups who have tried to use the scriptability and object passing of powershell extensively to accommodate a heterogeneous user community outside the realm of IT management. Do anybody have any tips or word of caution? Am I missing something obvious as to why this shouldn't be done? Shouldn't powershell be taking over the world? ;-)

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• how can i make sure to get the server response correctly when i invoke the server with QNetworkReque

  - by noname

  I wrote the server site call in Qt, but i haven't get the server response for every server invoking. I have to use the server reply to continue the program flow. The request is correctly reached to server and server do reply.The server is also on my machine. Here is the code how i make the server site call; QNetworkAccessManager nam1 = new QNetworkAccessManager(this); qnetmg=nam1; QObject::connect(nam1, SIGNAL(finished(QNetworkReply*)),this,SLOT(finishedGettingMarker(QNetworkReply*))); QString strurl="http://localhost:8080/ServerWeb"; QUrl url(strurl); QNetworkRequest preq(url); QNetworkReply* reply = nam1->get(preq); qreply=reply; Inside finisedGettingMarker slot, i have already eliminate for QNetworkReply-error case and i used one global variable for QNetworkAccessManager;"qnetmg" and one global variable for QNetworkReply;"qreply". And also i make qnetmg.disconnect(this,0); and qreply.abort(); inside that slot method. But the problem is i haven't got the response for every server invoking time. If anyone who know the way to solve it , please reply me. This situation happened only in Opera. Thanks in advance.

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• Should I learn two (or more) programming languages in parallel?

  - by c_maker

  I found entries on this site about learning a new programming language, however, I have not come across anything that talks about the advantages and disadvantages of learning two languages at the same time. Let's say my goal is to learn two new languages in a year. I understand that the definition of learning a new language is different for everyone and you can probably never know everything about a language. I believe in most cases the following things are enough to include the language in your resume and say that you are proficient in it (list is not in any particular order): Know its syntax so you can write a simple program in it Compare its underlying concepts with concepts of other languages Know best practices Know what libraries are available Know in what situations to use it Understand the flow of a more complex program At least know most of what you do not know I would probably look for a good book and pick an open source project for both of these languages to start with. My questions: Is it best to spend 5 months learning language#1 then 5 months learning language#2, or should you mix the two. Mixing them I mean you work on them in parallel. Should you pick two languages that are similar or different? Are there any advantages/disadvantages of let's say learning Lisp in tandem with Ruby? Is it a good idea to pick two languages with similar syntax or would it be too confusing? Please tell me what your experiences are regarding this. Does it make a difference if you are a beginner or a senior programmer?

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• switch statemt functioning improperly and giving error when i put break;

  - by nav

  The following is the code i used in a program - over here the month variable is an integer switch(month) { case 1: case 3: case 5: case 7: case 8: case 10: case 12: return 31; break; case 2: return 28; break; case 4: case 6: case 9: case 11: return 30; break; default: System.out.println("Invalid month."); return 0; } surprisingly, when i use the above switch construct.. it gives an error saying.. code unreachable for statements after each break statement Then i removed all the break statements, and the new code looks like this --- switch(month) { case 1: case 3: case 5: case 7: case 8: case 10: case 12: return 31; case 2: return 28; case 4: case 6: case 9: case 11: return 30; default: System.out.println("Invalid month."); return 0; } Now.. after removing the break statements .. the code worked perfectly well.. My question is... in the switch construct.. it is mandatory to use break.. or else the control flow continued.. and all the conditions are tested and executed!! right??? So why in the world is the previous ** syntactically Right** version giving an error.. and the modified syntactically incorrect version running perfectly well.. Any explanation.. anyone!!

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• What is the correct way to open and close window/dialog?

  - by mree

  I'm trying to develop a new program. The work flow looks like this: Login --> Dashboard (Window with menus) --> Module 1 --> Module 2 --> Module 3 --> Module XXX So, to open Dashboard from Login (a Dialog), I use Dashboard *d = new Dashboard(); d->show(); close(); In Dashboard, I use these codes to reopen the Login if the user closes the Window (by clicking the 'X') closeEvent(QCloseEvent *) { Login *login = new Login(); login->show(); } With a Task Manager opened, I ran the program and monitor the memory usage. After clicking open Dashboard from Login and closing Dashboard to return to Login, I noticed that the memory keeps increasing about 500 KB. It can goes up to 20 MB from 12 MB of memory usage by just opening and closing the window/dialog. So, what did I do wrong here ? I need to know it before I continue developing those modules which will definitely eat more memory with my programming. Thanks in advance.

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• Handling nulls in Datawarehouse

  - by rrydman

  I'd like to ask your input on what the best practice is for handling null or empty data values when it pertains to data warehousing and SSIS/SSAS. I have several fact and dimension tables that contain null values in different rows. Specifics: 1) What is the best way to handle null date/times values? Should I make a 'default' row in my time or date dimensions and point SSIS to the default row when there is a null found? 2) What is the best way to handle nulls/empty values inside of dimension data. Ex: I have some rows in an 'Accounts' dimensions that have empty (not NULL) values in the Account Name column. Should I convert these empty or null values inside the column to a specific default value? 3) Similar to point 1 above - What should I do if I end up with a Facttable row that has no record in one of the dimension columns? Do I need default dimension records for each dimension in case this happens? 4) Any suggestion or tips in regards to how to handle these operation in Sql server integration services (SSIS)? Best data flow configurations or best transformation objects to use would be helpful. Thanks :-)

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• how do I use an enum value on a switch statement in C++

  - by BotBotPgm

  I would like to use an enum value for my switch statment in C++. Is it possible to use the enum values enclosed in the "{}" as choices for the "switch()"? I know that switch() needs an integer value in order to direct the flow of programming to the appropriate case number. If this is the case, do I just make a variable for each constant in the 'enum' statment? I also want the user to be able to pick the choice and pass that choice to the switch() statement. for example: cout<< "1 - Easy"; cout<<"2 - Medium"; cout<< "3 -Hard"; enum myChoice {EASY =1 ,MEDIUM = 2, HARD = 3} cin ???? switch(????) case 1/EASY: (can I just type case EAST?) cout << "You picked easy!"; break; case 2/MEDIUM: cout << "You picked medium!"; case 3..... (same thing as case 2 except on hard.) default: return 0; Thanks

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• Slow loading of UITableView. How know why?

  - by mamcx

  I have a UITableView that show a long list of data. Use sections and follow the sugestion of http://stackoverflow.com/questions/695814/how-solve-slow-scrolling-in-uitableview . The flow is load a main UITableView & push a second selecting a row from there. However, with 3000 items take 11 seconds to show. I suspect first from the load of the records from sqlite (I preload the first 200). So I cut it to only 50. However, no matter if I preload only 1 or 500, the time is the same. The view is made from IB and all is opaque. I run out of ideas in how detect the problem. I run the Instruments tool but not know what to look. Also, when the user select a cell from the previous UITable, no visual feedback is show (ie: the cell not turn selected) for a while so he thinks he not select it and try several times. Is related to this problem. What to do? NOTE: The problem is only in the actual device: iPod Touch 2d generation Using fmdb as sqlite api Doing the caching in viewDidLoad Using NSDictionary for the caching Using a NSAutoreleasePool for the caching part. Only caching the row ID & mac 4 fields necesary to show the cell data UIView made with interface builder, SDK 2.2.1 Instruments say I use 2.5 MB in the device

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• Coloring Default Buttons - color filter only on unfocused state

  - by rlo

  I want to buttons of different colors, but I want to do so while using the default button background resource in order to preserve the onfocus and onclick states. This is because I want to use the default highlight color of the OS for my app, which is NOT always orange (HTC Sense makes it green). I found that adding a color filter to the button's background drawable works great (in this case, blue): myButton.getBackground().setColorFilter(Color.parseColor(this.getString (R.color.button_blue)), Mode.MULTIPLY); BUT, when the button is focused or clicked, it turns a nasty orange_blue because it mixes the color filter with the orange of the background drawable. I want to ONLY set this color filter for the unfocused/unclicked nine- patch drawable within the default button's statelistdrawable. I'm not sure how else to do this. I see a similar solution here: http://stackoverflow.com/questions/2065430/fixed-android-detecting-fo... but I have some concerns with that solution, mainly what if the OS changes the graphic of the default button? Since the normal unfocused/ unpressed graphic is now hardcoded into the app, it would break the flow. Maybe can someone comment on whether it would be good or bad practice to hardcode the default graphic into the app? What are the chances of the OS completely changing the graphic? Any help please? Thanks very much!!

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• JPA Problems mapping relationships

  - by Rosen Martev

  Hello. I have a problem when I try to persist my model. An exception is thrown when creating the EntityManagerFactory: Blockquote javax.persistence.PersistenceException: [PersistenceUnit: NIF] Unable to build EntityManagerFactory at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:677) at org.hibernate.ejb.HibernatePersistence.createEntityManagerFactory(HibernatePersistence.java:126) at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:52) at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:34) at project.serealization.util.PersistentManager.createSession(PersistentManager.java:24) at project.serealization.SerializationTest.testProject(SerializationTest.java:25) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at junit.framework.TestCase.runTest(TestCase.java:168) at junit.framework.TestCase.runBare(TestCase.java:134) at junit.framework.TestResult$1.protect(TestResult.java:110) at junit.framework.TestResult.runProtected(TestResult.java:128) at junit.framework.TestResult.run(TestResult.java:113) at junit.framework.TestCase.run(TestCase.java:124) at junit.framework.TestSuite.runTest(TestSuite.java:232) at junit.framework.TestSuite.run(TestSuite.java:227) at org.junit.internal.runners.JUnit38ClassRunner.run(JUnit38ClassRunner.java:79) at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:46) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197) Caused by: org.hibernate.HibernateException: Wrong column type in nif.action_element for column FLOW_ID. Found: double, expected: bigint at org.hibernate.mapping.Table.validateColumns(Table.java:284) at org.hibernate.cfg.Configuration.validateSchema(Configuration.java:1116) at org.hibernate.tool.hbm2ddl.SchemaValidator.validate(SchemaValidator.java:139) at org.hibernate.impl.SessionFactoryImpl.(SessionFactoryImpl.java:349) at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1327) at org.hibernate.cfg.AnnotationConfiguration.buildSessionFactory(AnnotationConfiguration.java:867) at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:669) ... 24 more The code for SimpleActionElement and SimpleFlow is as follows: @Entity public class SimpleActionElement { @OneToOne(cascade = CascadeType.ALL, targetEntity = SimpleFlow.class) @JoinColumn(name = "FLOW_ID") private SimpleFlow<T> flow; ... } @Entity public class SimpleFlow<T> { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "ELEMENT_ID") private Long element_id; ... }

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• Avoiding repetition with libraries that use a setup + execute model

  - by lijie

  Some libraries offer the ability to separate setup and execution, esp if the setup portion has undesirable characteristics such as unbounded latency. If the program needs to have this reflected in its structure, then it is natural to have: void setupXXX(...); // which calls the setup stuff void doXXX(...); // which calls the execute stuff The problem with this is that the structure of setupXXX and doXXX is going to be quite similar (at least textually -- control flow will prob be more complex in doXXX). Wondering if there are any ways to avoid this. Example: Let's say we're doing signal processing: filtering with a known kernel in the frequency domain. so, setupXXX and doXXX would probably be something like... void doFilter(FilterStuff *c) { for (int i = 0; i < c->N; ++i) { doFFT(c->x[i], c->fft_forward_setup, c->tmp); doMultiplyVector(c->tmp, c->filter); doFFT(c->tmp, c->fft_inverse_setup, c->x[i]); } } void setupFilter(FilterStuff *c) { setupFFT(..., &(c->fft_forward_setup)); // assign the kernel to c->filter ... setupFFT(..., &(c->fft_inverse_setup)); }

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• What is the best way to properly test object equality against an array of objects?

  - by radesix

  My objective is to abort the NSXMLParser when I parse an item that already exists in cache. The basic flow of the program works like this: 1) Program starts and downloads an XML feed. Each item in the feed is represented by a custom object (FeedItem). Each FeedItem gets added to an array. 2) When the parsing is complete the contents of the array (all FeedItem objects) are archived to the disk. The next time the program is executed or the feed is refreshed by the user I begin parsing again; however, since a cache (array) now exists as each item is parsed I want to see if the object exists in the cache. If it does then I know I have downloaded all the new items and no longer need to continue parsing. What I am learning, I think, is that I can't use indexOfObject or indexOfObjectIDenticalTo: because these really seem to be checking to see that the objects are using the same memory address (thus identical). What I want to do is see if the contents of the object are equal (or at least some of the contents). I've done some research and found that I can override the IsEqual method; however, I really don't want to iterate/enumerate through the entire cache contents table for every newly parsed XML FeedItem. Is iterating through the collection and testing each one for equality the only way to do this or is there a better technique I am not aware of? Currently I am using the following code though I know it needs to change: NSUInteger index = [self.feedListCache.feedList indexOfObject:self.currentFeedItem]; if (index == NSNotFound) { }

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• Strategies for testing reactive, asynchronous code

  - by Arne

  I am developing a data-flow oriented domain-specific language. To simplify, let's just look at Operations. Operations have a number of named parameters and can be asked to compute their result using their current state. To decide when an Operation should produce a result, it gets a Decision that is sensitive to which parameter got a value from who. When this Decision decides that it is fulfilled, it emits a Signal using an Observer. An Accessor listens for this Signal and in turn calls the Result method of the Operation in order to multiplex it to the parameters of other Operations. So far, so good, nicely decoupled design, composable and reusable and, depending on the specific Observer used, as asynchronous as you want it to be. Now here's my problem: I would love to start coding actual Tests against this design. But with an asynchronous Observer... how should I know that the whole signal-and-parameters-plumbing worked? Do I need to use time outs while waiting for a Signal in order to say that it was emitted successfully or not? How can I be, formally, sure that the Signal will not be emitted if I just wait a little longer (halting problem? ;-)) And, how can I be sure that the Signal was emitted because it was me who set a parameter, and not another Operation? It might well be that my test comes to early and sees a Signal that was emitted way before my setting a parameter caused a Decision to emit it. Currently, I guess the trivial cases are easy to test, but as soon as I want to test complex many-to-many - situations between operations I must resort to hoping that the design Just Works (tm)...

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• Patterns to deal with with functions that can have different kinds of results.

  - by KaptajnKold

  Suppose you have an method on an object that given the some input alters the objects state if the input validates according to some complex logic. Now suppose that when the input doesn't validate, it can be due to several different things, each of which we would like to be able to deal with in different ways. I'm sure many of you are thinking: That's what exceptions are for! I've thought of this also. But my reservation against using exceptions is that in some cases there is nothing exceptional about the input not validating and I really would like to avoid using exceptions to control what is really just in the expected flow of the program. If there were only one interpretation possible, I could simply choose to return a boolean value indicating whether or not the operation resulted in a state change or not and the respond appropriately when it did not. There is of course also the option to return a status code which the client can then choose to interpret or not. I don't like this much either because there is nothing semantic about status codes. The solution I have so far is to always check for each possible situation which I am able to handle before I call the method which then returns a boolean to inform the client if the object changed state. This leaves me the flexibility to handle as few or as many as the possible situations as I wish depending on the context I am in. It also has the benefit of making the method I am calling simpler to write. The drawback is that there is quite a lot of duplication in the client code wherever I call the method. Which of these solutions do you prefer and why? What other patterns do people use for providing meaningful feedback from functions? I know that some languages support multiple return values, and I if I had that option I would surely prefer it.

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• Objective C : UIButton image with NSArray in a random order

  - by Sarah

  Brief Idea about the flow : I have say minimum 1 and maximum 18 records in my database with a text and an image from which I have to fetch images and place any 3 of the same randomly to 3 UIButtons among which one image should match with my question. i.e. 1 is the answer and other 2 are the distractors. For Example : Question is : where is Apple? Now among the bunch of images, I want to place any 3 images on the 3 UIButtons(1 answer i.e. An Apple and 2 distractors) in a random order and on selecting the UIButton it should prompt me if it's a right answer or not. I am implementing below code for placing the UIImages in a random order : -(void) placeImages { NSMutableArray *images = [NSMutableArray arrayWithArray:arrImg]; NSArray *buttons = [NSArray arrayWithObjects:btn1,btn2,btn3, nil]; for (UIButton *btn in buttons) { int randomIndex= random() % images.count; UIImage *img = [images objectAtIndex:randomIndex]; [btn setImage:img forState:UIControlStateNormal]; [images removeObjectAtIndex:randomIndex]; } } But I am stuck at a point that how should I get 1 UIButton image with an answer and other as distractors also that how should i maintain the index of the image from the NSArray? Kindly guide me. Thank you.

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• BlackBerry Field class extension will not paint.

  - by jlindenbaum

  Using JRE 5.0.0, simulator device is an 8520. On a screen I am using a FlowFieldManager(Manager.VERTICAL_SCROLL) and adding Fields to it to show data. When I do this.flowManager = new FlowFieldManager(Manager.VERTICAL_SCROLL); Field field = new Field() { protected void paint(Graphics graphics) { graphics.drawTest("Test", 0, 0); } protected void layout(int width, int height) { this.setExtend(300, 300); // just testing } } this.flowManager.add(field); The screen renders correctly and 'Test' appears on the screen. If, on the other hand, I try and abstract this into a class called CustomField with the same properties and add it to the flow manager the render will not happen. Debugging shows that the device enters into the Object, into the layout function, but not the paint function. I can't figure out why the paint function is not called when I extend Field. The 4.5 API says that layout and paint are the only functions that I really need to extend. (getPreferredWidth and getPreferredHeight will be used to calculate screen sizes etc.) Thanks in advance.

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• What is the best practice when using UIStoryboards?

  - by Scott Sherwood

  Having used storyboards for a while now I have found them extremely useful however, they do have some limitations or at least unnatural ways of doing things. While it seems like a single storyboard should be used for your app, when you get to even a moderately sized application this presents several problems. Working within teams is made more difficult as conflicts in Storyboards can be problematic to resolve (any tips with this would also be welcome) The storyboard itself can become quite cluttered and unmanageable. So my question is what are the best practices of use? I have considered using a hybrid approach having logical tasks being split into separate storyboards, however this results in the UX flow being split between the code and the storyboard. To me this feels like the best way to create reusable actions such as login actions etc. Also should I still consider a place for Xibs? This article has quite a good overview of many of the issues and it proposes that for scenes that only have one screen, xibs should be used in this case. Again this feels unusual to me with Apples support for instantiating unconnected scenes from a storyboard it would suggest that xibs won't have a place in the future but I could be wrong.

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• recvfrom() return values in Stop-and-Wait UDP?

  - by mavErick

  I am trying to implement a Stop-and-Wait UDP client-server socket program in C. As known, there are basically three possible scenarios for Stop-and-Wait flow control. i.e., After transmitting a packet, the sender receives a correct ACK and thus starts transmitting the next packet; the sender receives an incorrect ACK and thus retransmits this packet; the sender receives no ACK within a TIMEOUT and thus retransmits this packet. My idea is to differentiate these three scenarios with the return value of recvfrom() on the sender side. For scenario 1&2: recvfrom() just returns the length of the received ACK. Since in my implementation the incorrect ACK is of the same length of the correct one, so I will have to go deeper and check the contents of the ACK. It's not a big deal. I know how to do. Problems come when I am trying to recognize scenario 3 where no ACK is received. What confuses me is that my recvfrom() is within a while loop, so the recvfrom() will be called constantly. What will it return when the receiver is not actually sending the sender ACK? Is it 0 or 1?

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• Dont understand the concept of extends in URL.openConnection() in JAVA

  - by user1722361

  Hi I am trying to learn JAVA deeply and so I am digging into the JDK source code in the following lines: URL url = new URL("http://www.google.com"); URLConnection tmpConn = url.openConnection(); I attached the source code and set the breakpoint at the second line and stepped into the code. I can see the code flow is: URL.openConnection() - sun.net.www.protocol.http.Handler.openConnection() I have two questions about this First In URL.openConnection() the code is: public URLConnection openConnection() throws java.io.IOException { return handler.openConnection(this); } handler is an object of URLStreamHandler, define as blow transient URLStreamHandler handler; But URLStreamHandler is a abstract class and method openConnection() is not implement in it so when handler calls this method, it should go to find a subclass who implement this method, right? But there are a lot classes who implement this methods in sun.net.www.protocol (like http.Hanlder, ftp.Handler ) How should the code know which "openConnection" method it should call? In this example, this handler.openConnection() will go into http.Handler and it is correct. (if I set the url as ftp://www.google.com, it will go into ftp.Handler) I cannot understand the mechanism. second. I have attached the source code so I can step into the JDK and see the variables but for many classes like sun.net.www.protocol.http.Handler, there are not source code in src.zip. I googled this class and there is source code online I can get but why they did not put it (and many other classes) in the src.zip? Where can I find a comprehensive version of source code? Thanks!

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• Best (in your opinion) GIT workflow for case when releases are done on demand (in most cases 1-2 tickets at once)

  - by Robert

  I'm rather a Git newbie and I'm looking for your advice. In the company I work for we have a "workflow" where we have a single Git repo for our project with 2 branches: master and prod. All devs work on the master branch. If a ticket is done (from the dev perspective), we push to the repo. If all tests are passed, we make a release. The issue is that in most cases, the request from business guys sounds like: "please release ticket A or A && B". In most cases, I end up doing something like git checkout prod git cherry-pick --no-commit commit_hash git commit -m "blah blah to prod" -a As you can see this is not a perfect solution, and I'm under a huge impression this is a perfect way to nowhere especially when change A depends on changes B and C. Do you have any suggestions how to handle releases on demand if more devs works on the same branch and the flow looks like I described above? All suggestions are welcome. I cannot change business processes and it will have to stay as it is - unfortunately.

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• From Binary to Data Structures

  - by Cédric Menzi

  Table of Contents Introduction PE file format and COFF header COFF file header BaseCoffReader Byte4ByteCoffReader UnsafeCoffReader ManagedCoffReader Conclusion History This article is also available on CodeProject Introduction Sometimes, you want to parse well-formed binary data and bring it into your objects to do some dirty stuff with it. In the Windows world most data structures are stored in special binary format. Either we call a WinApi function or we want to read from special files like images, spool files, executables or may be the previously announced Outlook Personal Folders File. Most specifications for these files can be found on the MSDN Libarary: Open Specification In my example, we are going to get the COFF (Common Object File Format) file header from a PE (Portable Executable). The exact specification can be found here: PECOFF PE file format and COFF header Before we start we need to know how this file is formatted. The following figure shows an overview of the Microsoft PE executable format. Source: Microsoft Our goal is to get the PE header. As we can see, the image starts with a MS-DOS 2.0 header with is not important for us. From the documentation we can read "...After the MS DOS stub, at the file offset specified at offset 0x3c, is a 4-byte...". With this information we know our reader has to jump to location 0x3c and read the offset to the signature. The signature is always 4 bytes that ensures that the image is a PE file. The signature is: PE\0\0. To prove this we first seek to the offset 0x3c, read if the file consist the signature. So we need to declare some constants, because we do not want magic numbers.   private const int PeSignatureOffsetLocation = 0x3c; private const int PeSignatureSize = 4; private const string PeSignatureContent = "PE";   Then a method for moving the reader to the correct location to read the offset of signature. With this method we always move the underlining Stream of the BinaryReader to the start location of the PE signature.   private void SeekToPeSignature(BinaryReader br) { // seek to the offset for the PE signagure br.BaseStream.Seek(PeSignatureOffsetLocation, SeekOrigin.Begin); // read the offset int offsetToPeSig = br.ReadInt32(); // seek to the start of the PE signature br.BaseStream.Seek(offsetToPeSig, SeekOrigin.Begin); }   Now, we can check if it is a valid PE image by reading of the next 4 byte contains the content PE.   private bool IsValidPeSignature(BinaryReader br) { // read 4 bytes to get the PE signature byte[] peSigBytes = br.ReadBytes(PeSignatureSize); // convert it to a string and trim \0 at the end of the content string peContent = Encoding.Default.GetString(peSigBytes).TrimEnd('\0'); // check if PE is in the content return peContent.Equals(PeSignatureContent); }   With this basic functionality we have a good base reader class to try the different methods of parsing the COFF file header. COFF file header The COFF header has the following structure: Offset Size Field 0 2 Machine 2 2 NumberOfSections 4 4 TimeDateStamp 8 4 PointerToSymbolTable 12 4 NumberOfSymbols 16 2 SizeOfOptionalHeader 18 2 Characteristics If we translate this table to code, we get something like this:   [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)] public struct CoffHeader { public MachineType Machine; public ushort NumberOfSections; public uint TimeDateStamp; public uint PointerToSymbolTable; public uint NumberOfSymbols; public ushort SizeOfOptionalHeader; public Characteristic Characteristics; } BaseCoffReader All readers do the same thing, so we go to the patterns library in our head and see that Strategy pattern or Template method pattern is sticked out in the bookshelf. I have decided to take the template method pattern in this case, because the Parse() should handle the IO for all implementations and the concrete parsing should done in its derived classes.   public CoffHeader Parse() { using (var br = new BinaryReader(File.Open(_fileName, FileMode.Open, FileAccess.Read, FileShare.Read))) { SeekToPeSignature(br); if (!IsValidPeSignature(br)) { throw new BadImageFormatException(); } return ParseInternal(br); } } protected abstract CoffHeader ParseInternal(BinaryReader br);   First we open the BinaryReader, seek to the PE signature then we check if it contains a valid PE signature and rest is done by the derived implementations. Byte4ByteCoffReader The first solution is using the BinaryReader. It is the general way to get the data. We only need to know which order, which data-type and its size. If we read byte for byte we could comment out the first line in the CoffHeader structure, because we have control about the order of the member assignment.   protected override CoffHeader ParseInternal(BinaryReader br) { CoffHeader coff = new CoffHeader(); coff.Machine = (MachineType)br.ReadInt16(); coff.NumberOfSections = (ushort)br.ReadInt16(); coff.TimeDateStamp = br.ReadUInt32(); coff.PointerToSymbolTable = br.ReadUInt32(); coff.NumberOfSymbols = br.ReadUInt32(); coff.SizeOfOptionalHeader = (ushort)br.ReadInt16(); coff.Characteristics = (Characteristic)br.ReadInt16(); return coff; }   If the structure is as short as the COFF header here and the specification will never changed, there is probably no reason to change the strategy. But if a data-type will be changed, a new member will be added or ordering of member will be changed the maintenance costs of this method are very high. UnsafeCoffReader Another way to bring the data into this structure is using a "magically" unsafe trick. As above, we know the layout and order of the data structure. Now, we need the StructLayout attribute, because we have to ensure that the .NET Runtime allocates the structure in the same order as it is specified in the source code. We also need to enable "Allow unsafe code (/unsafe)" in the project's build properties. Then we need to add the following constructor to the CoffHeader structure.   [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)] public struct CoffHeader { public CoffHeader(byte[] data) { unsafe { fixed (byte* packet = &data[0]) { this = *(CoffHeader*)packet; } } } }   The "magic" trick is in the statement: this = *(CoffHeader*)packet;. What happens here? We have a fixed size of data somewhere in the memory and because a struct in C# is a value-type, the assignment operator = copies the whole data of the structure and not only the reference. To fill the structure with data, we need to pass the data as bytes into the CoffHeader structure. This can be achieved by reading the exact size of the structure from the PE file.   protected override CoffHeader ParseInternal(BinaryReader br) { return new CoffHeader(br.ReadBytes(Marshal.SizeOf(typeof(CoffHeader)))); }   This solution is the fastest way to parse the data and bring it into the structure, but it is unsafe and it could introduce some security and stability risks. ManagedCoffReader In this solution we are using the same approach of the structure assignment as above. But we need to replace the unsafe part in the constructor with the following managed part:   [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)] public struct CoffHeader { public CoffHeader(byte[] data) { IntPtr coffPtr = IntPtr.Zero; try { int size = Marshal.SizeOf(typeof(CoffHeader)); coffPtr = Marshal.AllocHGlobal(size); Marshal.Copy(data, 0, coffPtr, size); this = (CoffHeader)Marshal.PtrToStructure(coffPtr, typeof(CoffHeader)); } finally { Marshal.FreeHGlobal(coffPtr); } } }     Conclusion We saw that we can parse well-formed binary data to our data structures using different approaches. The first is probably the clearest way, because we know each member and its size and ordering and we have control about the reading the data for each member. But if add member or the structure is going change by some reason, we need to change the reader. The two other solutions use the approach of the structure assignment. In the unsafe implementation we need to compile the project with the /unsafe option. We increase the performance, but we get some security risks.

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• Ajax Control Toolkit and Superexpert

  - by Stephen Walther

  Microsoft has asked my company, Superexpert Consulting, to take ownership of the development and maintenance of the Ajax Control Toolkit moving forward. In this blog entry, I discuss our strategy for improving the Ajax Control Toolkit. Why the Ajax Control Toolkit? The Ajax Control Toolkit is one of the most popular projects on CodePlex. In fact, some have argued that it is among the most successful open-source projects of all time. It consistently receives over 3,500 downloads a day (not weekends -- workdays). A mind-boggling number of developers use the Ajax Control Toolkit in their ASP.NET Web Forms applications. Why does the Ajax Control Toolkit continue to be such a popular project? The Ajax Control Toolkit fills a strong need in the ASP.NET Web Forms world. The Toolkit enables Web Forms developers to build richly interactive JavaScript applications without writing any JavaScript. For example, by taking advantage of the Ajax Control Toolkit, a Web Forms developer can add modal dialogs, popup calendars, and client tabs to a web application simply by dragging web controls onto a page. The Ajax Control Toolkit is not for everyone. If you are comfortable writing JavaScript then I recommend that you investigate using jQuery plugins instead of the Ajax Control Toolkit. However, if you are a Web Forms developer and you don’t want to get your hands dirty writing JavaScript, then the Ajax Control Toolkit is a great solution. The Ajax Control Toolkit is Vast The Ajax Control Toolkit consists of 40 controls. That’s a lot of controls (For the sake of comparison, jQuery UI consists of only 8 controls – those slackers J). Furthermore, developers expect the Ajax Control Toolkit to work on browsers both old and new. For example, people expect the Ajax Control Toolkit to work with Internet Explorer 6 and Internet Explorer 9 and every version of Internet Explorer in between. People also expect the Ajax Control Toolkit to work on the latest versions of Mozilla Firefox, Apple Safari, and Google Chrome. And, people expect the Ajax Control Toolkit to work with different operating systems. Yikes, that is a lot of combinations. The biggest challenge which my company faces in supporting the Ajax Control Toolkit is ensuring that the Ajax Control Toolkit works across all of these different browsers and operating systems. Testing, Testing, Testing Because we wanted to ensure that we could easily test the Ajax Control Toolkit with different browsers, the very first thing that we did was to set up a dedicated testing server. The dedicated server -- named Schizo -- hosts 4 virtual machines so that we can run Internet Explorer 6, Internet Explorer 7, Internet Explorer 8, and Internet Explorer 9 at the same time (We also use the virtual machines to host the latest versions of Firefox, Chrome, Opera, and Safari). The five developers on our team (plus me) can each publish to a separate FTP website on the testing server. That way, we can quickly test how changes to the Ajax Control Toolkit affect different browsers. QUnit Tests for the Ajax Control Toolkit Introducing regressions – introducing new bugs when trying to fix existing bugs – is the concern which prevents me from sleeping well at night. There are so many people using the Ajax Control Toolkit in so many unique scenarios, that it is difficult to make improvements to the Ajax Control Toolkit without introducing regressions. In order to avoid regressions, we decided early on that it was extremely important to build good test coverage for the 40 controls in the Ajax Control Toolkit. We’ve been focusing a lot of energy on building automated JavaScript unit tests which we can use to help us discover regressions. We decided to write the unit tests with the QUnit test framework. We picked QUnit because it is quickly becoming the standard unit testing framework in the JavaScript world. For example, it is the unit testing framework used by the jQuery team, the jQuery UI team, and many jQuery UI plugin developers. We had to make several enhancements to the QUnit framework in order to test the Ajax Control Toolkit. For example, QUnit does not support tests which include postbacks. We modified the QUnit framework so that it works with IFrames so we could perform postbacks in our automated tests. At this point, we have written hundreds of QUnit tests. For example, we have written 135 QUnit tests for the Accordion control. The QUnit tests are included with the Ajax Control Toolkit source code in a project named AjaxControlToolkit.Tests. You can run all of the QUnit tests contained in the project by opening the Default.aspx page. Automating the QUnit Tests across Multiple Browsers Automated tests are useless if no one ever runs them. In order for the QUnit tests to be useful, we needed an easy way to run the tests automatically against a matrix of browsers. We wanted to run the unit tests against Internet Explorer 6, Internet Explorer 7, Internet Explorer 8, Internet Explorer 9, Firefox, Chrome, and Safari automatically. Expecting a developer to run QUnit tests against every browser after every check-in is just too much to expect. It takes 20 seconds to run the Accordion QUnit tests. We are testing against 8 browsers. That would require the developer to open 8 browsers and wait for the results after each change in code. Too much work. Therefore, we built a JavaScript Test Server. Our JavaScript Test Server project was inspired by John Resig’s TestSwarm project. The JavaScript Test Server runs our QUnit tests in a swarm of browsers (running on different operating systems) automatically. Here’s how the JavaScript Test Server works: 1. We created an ASP.NET page named RunTest.aspx that constantly polls the JavaScript Test Server for a new set of QUnit tests to run. After the RunTest.aspx page runs the QUnit tests, the RunTest.aspx records the test results back to the JavaScript Test Server. 2. We opened the RunTest.aspx page on instances of Internet Explorer 6, Internet Explorer 7, Internet Explorer 8, Internet Explorer 9, FireFox, Chrome, Opera, Google, and Safari. Now that we have the JavaScript Test Server setup, we can run all of our QUnit tests against all of the browsers which we need to support with a single click of a button. A New Release of the Ajax Control Toolkit Each Month The Ajax Control Toolkit Issue Tracker contains over one thousand five hundred open issues and feature requests. So we have plenty of work on our plates J At CodePlex, anyone can vote for an issue to be fixed. Originally, we planned to fix issues in order of their votes. However, we quickly discovered that this approach was inefficient. Constantly switching back and forth between different controls was too time-consuming. It takes time to re-familiarize yourself with a control. Instead, we decided to focus on two or three controls each month and really focus on fixing the issues with those controls. This way, we can fix sets of related issues and avoid the randomization caused by context switching. Our team works in monthly sprints. We plan to do another release of the Ajax Control Toolkit each and every month. So far, we have competed one release of the Ajax Control Toolkit which was released on April 1, 2011. We plan to release a new version in early May. Conclusion Fortunately, I work with a team of smart developers. We currently have 5 developers working on the Ajax Control Toolkit (not full-time, they are also building two very cool ASP.NET MVC applications). All the developers who work on our team are required to have strong JavaScript, jQuery, and ASP.NET MVC skills. In the interest of being as transparent as possible about our work on the Ajax Control Toolkit, I plan to blog frequently about our team’s ongoing work. In my next blog entry, I plan to write about the two Ajax Control Toolkit controls which are the focus of our work for next release.

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• TFS, G.I. Joe and Under-doing

  If I were to rank the most consistently irritating parts of my work day, using TFS would come in first by a wide margin. Even repeated network outages this week seem like a pleasant reprieve from this monolithic beast. This is not a reflexive anti-Microsoft feeling, that attitude just wouldnt work for a consultant who does .NET development. It is also not an utter dismissal of TFS as worthless; Ive seen people use it effectively on several projects. So why? Ill start with a laundry list of shortcomings. An out of the box UI for work items that is insultingly bad, a source control system that is confoundingly fragile when handling merges, folder renames and long file names, the arcane XML wizardry necessary to customize a template and a build system that adds an extra layer of oddness on top of msbuild. Im sure my legion of readers will soon point out to me how I can work around all these issues, how this is fixed in TFS 2010 or with this add-in, and how once you have everything set up, youre fine. And theyd be right, any one of these problems could be worked around. If not dirty laundry, what else? I thought about it for a while, and came to the conclusion that TFS is so irritating to me because it represents a vision of software development that I find unappealing. To expand upon this, lets start with some wisdom from those great PSAs at the end of the G.I. Joe cartoons of the 80s: Now you know, and knowing is half the battle. In software development, Id go further and say knowing is more than half the battle. Understanding the dimensions of the problem you are trying to solve, the needs of the users, the value that your software can provide are more than half the battle. Implementation of this understanding is not easy, but it is not even possible without this knowledge. Assuming we have a fixed amount of time and mental energy for any project, why does this spell trouble for TFS? If you think about what TFS is doing, its offering you a huge array of options to track the day to day implementation of your project. From tasks, to code churn, to test coverage. All valuable metrics, but only in exchange for valuable time to get it all working. In addition, when you have a shiny toy like TFS, the temptation is to feel obligated to use it. So the push from TFS is to encourage a project manager and team to focus on process and metrics around process. You can get great visibility, and graphs to show your project stakeholders, but none of that is important if you are not implementing the right product. Not just unimportant, these activities can be harmful as they drain your time and sap your creativity away from the rest of the project. To be more concrete, lets suppose your organization has invested the time to create a template for your projects and trained people in how to use it, so there is no longer a big investment of time for each project to get up and running. First, Id challenge if that template could be specific enough to be full featured and still applicable for any project. Second, the very existence of this template would be a indication to a project manager that the success of their project was somehow directly related to fitting management of that project into this format. Again, while the capabilities are wonderful, the mirage is there; just get everything into TFS and your project will run smoothly. Ill close the loop on this first topic by proposing a thought experiment. Think of the projects youve worked on. How many times have you been chagrined to discover youve implemented the wrong feature, misunderstood how a feature should work or just plain spent too much time on a screen that nobody uses? That sounds like a really worthwhile area to invest time in improving. How about going back to these projects and thinking about how many times you wished you had optimized the state change flow of your tasks or been embarrassed to not have a code churn report linked back to the latest changeset? With thanks to the Real American Heroes, Ill move on to a more current influence, that of the developers at 37signals, and their philosophy towards software development. This philosophy, fully detailed in the books Getting Real and Rework, is a vision of software that under does the competition. This is software that is deliberately limited in functionality in order to concentrate fully on making sure ever feature that is there is awesome and needed. Why is this relevant? Well, in one of those fun seeming paradoxes in life, constraints can be a spark for creativity. Think Twitter, the small screen of an iPhone, the limitations of HTML for applications, the low memory limits of older or embedded system. As long as there is some freedom within those constraints, amazing things emerge. For project management, some of the most respected people in the industry recommend using just index cards, pens and tape. They argue that with change the constant in software development, your process should be as limited (yet rigorous) as possible. Looking at TFS, this is not a system designed to under do anybody. It is a big jumble of components and options, with every feature you could think of. Predictably this means many basic functions are hard to use. For task management, many people just use an Excel spreadsheet linked up to TFS. Not a stirring endorsement of the tooling there. TFS as a whole would be far more appealing to me if there was less of it, but better. Id cut 50% of the features to make the other half really amaze and inspire me. And thats really the heart of the matter. TFS has great promise and I want to believe it can work better. But ultimately it focuses your attention on a lot of stuff that doesnt really matter and then clamps down your creativity in a mess of forms and dialogs obscuring what does.   --- Relevant Links --- All those great G.I. Joe PSAs are on YouTube, including lots of mashed up versions. A simple Google search will get you on the right track.Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Hey, Google: It’s Time to Add Multi-Window Multitasking To Android

  - by Chris Hoffman

  In 2012, Google’s Dianne Hackborn threatened to revoke CyanogenMod’s access to the Android Market if they moved forward with adding “Cornerstone” multitasking to their custom ROM. Samsung has since created their own multi-window multitasking feature. Dianne Hackborn said this “is something that needs to be done at the mainline platform level” so apps wouldn’t break. She was right — Android needs this as a standard feature and it’s time for Google to provide it. Doesn’t Android Have Multitasking? Android originally stood out from Apple’s iOS with its powerful multitasking. Applications can continue running in the background while you’re using another application. This makes Android powerful — you can even have BitTorrent clients downloading files in the background while using another app. Android still kept the design of a single app on screen at a time. This made a lot of sense when Android only ran on smartphones with small screens. Today, Android runs on everything from smaller smartphones all the way up to huge “phablets” like the Galaxy Note. Android has gone beyond phones and runs on 12-inch tablets, convertibles with keyboard docks, laptops, and even Android desktops. Android isn’t just a phone operating system. Samsung’s Multi-Window Isn’t Good Enough Samsung has tried to add value to Android by adding a multi-window feature. When you’re using a high-end phone like the Galaxy Note or Galaxy S, or a Galaxy tablet, you have the ability to run certain apps side-by-side with each other. There are big problems here. This only works on Samsung devices, and only on specific Samsung devices. To add support for this feature in a way that doesn’t break other apps, Samsung’s multi-window feature also only works with specific apps. You can’t just run any app in multi-window view, only the apps on the Multi Window bar Samsung provides. This prevents third-party apps from breaking, which is what Google was worried about with CyanogenMod’s Cornerstone feature. A feature that only works with a handful of apps on specific devices from a single manufacturer isn’t good enough. This feature needs to work on every Android device — or at least ones with suitably large screens and powerful enough internals. It needs to be an Android platform feature so application developers can ensure their apps will work properly with it on every device. Android developers shouldn’t have to add support for each manufacturer’s own multi-window feature if other manufacturers decide to copy Samsung. Floating Apps Are a Dirty Hack Floating apps also enable real multitasking. Remember that Android allows apps to run in the background while you’re using an app in the foreground. These apps can present interfaces that appear floating above the current app — think of it like using “always on top” to make a window always appear over every other app on a desktop operating system. You can install floating apps to browse the web, take notes, chat, and watch videos while using any app. Only apps specifically designed to run as floating apps will work, so you have to seek them out. Floating apps are also awkward to use because they float over the app you’re using, blocking parts of its interface. Microsoft added floating-window support to Skype for Android. You can have a video conversation and the other person’s face will always appear on your screen, even when you leave the Skype app. Microsoft is using more of Android’s multi-window multitasking power than Google is. Custom ROMs and Root-Only Tweaks Aren’t Acceptable Some custom ROMs are adding this feature to Android. Google threatened to revoke CyanogenMod’s access to the Android Market (now known as Google Play) if they added this feature because it could potentially break third-party apps. Today, other custom ROMs are working on split-screen multitasking. Samsung added their own version to their own devices. You can also get this feature by using a root-only Xposed Framework tweak known as XMultiWindow. If you have root access, you can get multi-window multitasking or any app on your device. This shouldn’t require rooting your device or installing a custom ROM. These third-party solutions often have awkward interfaces and bugs. We need an integrated, supported solution that works the same on every device. Why Multi-Window is Important Microsoft’s Windows 8.1 stands out among tablet operating systems for its powerful multitasking support, allowing you to view several apps side-by-side at the same time. Apple is also reported to be working on adding side-by-side apps to the iPad with iOS 8. On every competitor’s operating system, you’ll be able to view a web page while you write an email, watch a video while you browse the web, or chat with someone while you do anything else. But Android’s still remained frozen in time. Despite all Android’s underlying power — and despite the way Android allows apps to adapt to different screen sizes — Google is resisting adding this feature. Large-screen Android tablets like the Nexus 10 (remember that tablet Google hasn’t updated in over 18 months?) need this feature. So do huge phones, convertibles, laptops, and Android desktops. If tablets are the future of personal computing, we should be able to do more than one thing at a time on our tablets’ big screens. Microsoft, Samsung, and even Apple are realizing this — now it’s Google’s turn. Image Credit: Sergey Galyonkin on Flickr, Karlis Dambrans on Flickr

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