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  • Caching Authentication Data

    - by PartlyCloudy
    Hi, I'm currently implementing a REST web service using CouchDB and RESTlet. The RESTlet layer is mainly for authentication and some minor filtering of the JSON data served by CouchDB: Clients <= HTTP = [ RESTlet <= HTTP = CouchDB ] I'm using CouchDB also to store user login data, because I don't want to add an additional database server for that purpose. Thus, each request to my service causes two CouchDB requests conducted by RESTlet (auth data + "real" request). In order to keep the service as efficent as possible, I want to reduce the number of requests, in this case redundant requests for login data. My idea now is to provide a cache (i.e.LRU-Cache via LinkedHashMap) within my RESTlet application that caches login data, because HTTP caching will probabily not be enough. But how do I invalidate the cache data, once a user changes the password, for instance. Thanks to REST, the application might run on several servers in parallel, and I don't want to create a central instance just to cache login data. Currently, I save requested auth data in the cache and try to auth new requests by using them. If a authentication fails or there is now entry available, I'll dispatch a GET request to my CouchDB storage in order to obtain the actual auth data. So in a worst case, users that have changed their data will perhaps still be able to login with their old credentials. How can I deal with that? Or what is a good strategy to keep the cache(s) up-to-date in general? Thanks in advance.

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  • JUnit Test method with randomized nature

    - by Peter
    Hey, I'm working on a small project for myself at the moment and I'm using it as an opportunity to get acquainted with unit testing and maintaining proper documentation. I have a Deck class with represents a deck of cards (it's very simple and, to be honest, I can be sure that it works without a unit test, but like I said I'm getting used to using unit tests) and it has a shuffle() method which changes the order of the cards in the deck. The implementation is very simple and will certainly work: public void shuffle() { Collections.shuffle(this.cards); } But, how could I implement a unit test for this method. My first thought was to check if the top card of the deck was different after calling shuffle() but there is of course the possibility that it would be the same. My second thought was to check if the entire order of cards has changed, but again they could possibly be in the same order. So, how could I write a test that ensures this method works in all cases? And, in general, how can you unit test methods for which the outcome depends on some randomness? Cheers, Pete

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  • Unable to create a breakpoint in Eclipse and Tomcat

    - by Traroth
    Since yesterday, I get a strange error message when I start my Tomcat (6.0.35) under Eclipse Juno (build 20120614-1722): Among the things I tried in order to get rid of the error: Check in Preferences - Java - Compiler if all "Classfile Generation" checkboxes where checked. I did that for both general preferences and project preference Uncheck them, build, check them build again (found on another question) Add org.eclipse.jdt.core.compiler.debug.lineNumber=generate to my .settings/org.eclipse.jdt.core.prefs file Use a new CVS checkout (same symptoms) And now, I don't know what to do anymore. The problem is really stopping me from get anything done. I can't work anymore. Crazy is: the problem doesn't happen on every class, only on some of them. Neither does it happen on my other Eclipse projects. And it didn't happen before yesterday, even if I can't remeber having done anything weird. Actually, I have never seen a problem like this in almost 10 years I'm using Eclipse... If you have any idea, I would be really grateful... Edit: I also tried to ignore the message and go on with my tests: If I create another breakpoint upstream from my problematic class, when I enter this problematic class, it tries to open a $Proxy132 class, which means it actually opens an empty page, with a source not found message

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  • Put together tiles in android sdk and use as background

    - by Jon
    In a feeble attempt to learn some Android development am I stuck at graphics. My aim here is pretty simple: Take n small images and build a random image, larger than the screen with possibility to scroll around. Have an animated object move around on it I have looked at the SDK examples, Lunar Lander especially but there are a few things I utterly fail to wrap my head around. I've got a birds view plan (which in my head seems reasonably sane): How do I merge the tiles into one large image? The background is static so I figure I should do like this: Make a 2d array with refs to the tiles Make a large Drawable and draw the tiles on it At init draw this big image as the background At each onDraw redraw the background of the previous spot of the moving object, and the moving object at its new location The problem is the hands on things. I load the small images with "Bitmap img1 = BitmapFactory.decodeResource (res, R.drawable.img1)", but then what? Should I make a canvas and draw the images on it with "canvas.drawBitmap (img1, x, y, null);"? If so how to get a Drawable/Bitmap from that? I'm totally lost here, and would really appreciate some hands on help (I would of course be grateful for general hints as well, but I'm primarily trying to understand the Graphics objects). To make you, dear reader, see my level of confusion will I add my last desperate try: Drawable drawable; Canvas canvas = new Canvas (); Bitmap img1 = BitmapFactory.decodeResource (res, R.drawable.img1); // 50 x 100 px image Bitmap img2 = BitmapFactory.decodeResource (res, R.drawable.img2); // 50 x 100 px image canvas.drawBitmap (img1, 0, 0, null); canvas.drawBitmap (img2, 50, 0, null); drawable.draw (canvas); // obviously wrong as draw == null this.setBackground (drawable); Thanks in advance

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  • how to filter files from the root "classes" and "test-classes" folders in Eclipse?

    - by Kidburla
    I am using ClearCase in my application which generates a whole load of ".copyarea.db" files (one in every folder). These cause conflicts when publishing to Tomcat as Eclipse will bundle the "classes" and "test-classes" folders into one JAR (not sure why it does this - as there is no need to have test classes available on the application server). Any folders with the same names will have a separate .copyarea.db in the classes and test-classes branches. I managed to get around this problem in general by adding ".copyarea.db" to the Filtered resources on the Java->Compiler->Building->Output Folder preference page. This stops the file appearing in source output (package/class folders), the vast majority of cases. However there remains the problem of the root folder, i.e. "target/classes/.copyarea.db" and "target/test-classes/.copyarea.db". These files are not filtered as they are not part of the compile task. Just deleting the files manually doesn't help either, as Eclipse expects to find them and doesn't. How can I exclude these ".copyarea.db" files from the root "classes" and "test-classes" folders?

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  • How can one convince a team to use a new technology (LinQ, MVC, etc )?

    - by Atomiton
    Obviously, it's easier to do with some developers, but I'm sure many of us are on teams that prefer the status quo. You know the type. You see some benefit in a piece of new technology and they prefer the tried and true methods. Try, for example, DBA/C# programmer the advantages of using LinQ ( not necessarily LinQ to SQL, just LinQ in general ). For example, When a project requirement is to be cross-platform... instead of thinking about how one can run Windows on a Mac through a VM Machine, introducing the idea of using relatively new Silverlight or creating it in Java ( as an option to look into ). I know most people don't like to be out of their comfort level, so it takes a bit of convincing, and not ALL new technology makes business sense... but how have you convinced your team to look at a new technology? What technologies have you successfully introduced to your workplace? What technologies do you think are hardest to introduce? ( I'm thinking paradigm-shifting ones, like MVC from WebForms... or new languages ) What strategies do you employ to make these new technologies appealing?

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  • How to implement a network protocol?

    - by gotch4
    Here is a generic question. I'm not in search of the best answer, I'd just like you to express your favourite practices. I want to implement a network protocol in Java (but this is a rather general question, I faced the same issues in C++), this is not the first time, as I have done this before. But I think I am missing a good way to implement it. In fact usually it's all about exchanging text messages and some byte buffers between hosts, storing the status and wait until the next message comes. The problem is that I usually end up with a bunch of switch and more or less complex if statements that react to different statuses / messages. The whole thing usually gets complicated and hard to mantain. Not to mention that sometimes what comes out has some "blind spot", I mean statuses of the protocol that have not been covered and that behave in a unpredictable way. I tried to write down some state machine classes, that take care of checking start and end statuses for each action in more or less smart ways. This makes programming the protocol very complicated as I have to write lines and lines of code to cover every possible situation. What I'd like is something like a good pattern, or a best practice that is used in programming complex protocols, easy to mantain and to extend and very readable. What are your suggestions?

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  • JPA/Hibernate Parent/Child relationship

    - by NubieJ
    Hi I am quite new to JPA/Hibernate (Java in general) so my question is as follows (note, I have searched far and wide and have not come across an answer to this): I have two entities: Parent and Child (naming changed). Parent contains a list of Children and Children refers back to parent. e.g. @Entity public class Parent { @Id @Basic @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "PARENT_ID", insertable = false, updatable = false) private int id; /* ..... */ @OneToMany(cascade = { CascadeType.ALL }, fetch = FetchType.LAZY) @JoinColumn(name = "PARENT_ID", referencedColumnName = "PARENT_ID", nullable = true) private Set<child> children; /* ..... */ } @Entity public class Child { @Id @Basic @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "CHILD_ID", insertable = false, updatable = false) private int id; /* ..... */ @ManyToOne(cascade = { CascadeType.REFRESH }, fetch = FetchType.EAGER, optional = false) @JoinColumn(name = "PARENT_ID", referencedColumnName = "PARENT_ID") private Parent parent; /* ..... */ } I want to be able to do the following: Retrieve a Parent entity which would contain a list of all its children (List), however, when listing Parent (getting List, it of course should omit the children from the results, therefore setting FetchType.LAZY. Retrieve a Child entity which would contain an instance of the Parent entity. Using the code above (or similar) results in two exceptions: Retrieving Parent: A cycle is detected in the object graph. This will cause infinitely deep XML... Retrieving Child: org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: xxxxxxxxxxx, no session or session was closed When retrieving the Parent entity, I am using a named query (i.e. calling it specifically) @NamedQuery(name = "Parent.findByParentId", query = "SELECT p FROM Parent AS p LEFT JOIN FETCH p.children where p.id = :id") Code to get Parent (i.e. service layer): public Parent findByParentId(int parentId) { Query query = em.createNamedQuery("Parent.findByParentId"); query.setParameter("id", parentId); return (Parent) query.getSingleResult(); } Why am I getting a LazyInitializationException event though the List property on the Parent entity is set as Lazy (when retrieving the Child entity)?

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  • How to design authentication in a thick client, to be fail safe?

    - by Jay
    Here's a use case: I have a desktop application (built using Eclipse RCP) which on start, pops open a dialog box with 'UserName' and 'Password' fields in it. Once the end user, inputs his UserName and Password, a server is contacted (a spring remote-servlet, with the client side being a spring httpclient: similar to the approaches here.), and authentication is performed on the server side. A few questions related to the above mentioned scenario: If said this authentication service were to go down, what would be the best way to handle further proceedings? Authentication is something that I cannot do away with. Would running the desktop client in a "limited" mode be a good idea? For instance, important features/menus/views will be disabled, rest of the application will be accessible? Should I have a back up authentication service running on a different machine, working as a backup? What are the general best-practices in this scenario? I remember reading about google gears and how it would let you edit and do stuff offline - should something like this be designed? Please let me know your design/architectural comments/suggestions. Appreciate your help.

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  • Implemeting web-based autocomplete for structured input

    - by ravigad
    I am looking to implement web-based autocomplete for structured commands. So, for example, suppose I was trying to implement a web-based Windows command line with autocomplete, in such a case I would want to suggest all the available commands, then, once a user selects a command, all the options for that command, then if a user enters a switch (say '-' dash or '/' slash) then offer all the switches for that command and all the relevant values that can follow, and so on. All from the same text input box. If you have used version 4.0 of JIRA, I am thinking of something similar to the JQL search input box that they have implemented. I have not managed to find any tutorials that look at this scenario end-to-end (which is a shame, because it would be great to see more applications that do this). What I am looking for is some guidance on the steps needed to implement this solution: Do you have any experience implementing such a solution and if so what components did you use? Would you use a framework such as ANTLR to provide the available options to the end user? If not what would do? Sorry for raising such a general question, but my main problem is working out how the pieces fit together as opposed to, say, how to do autocomplete or how to parse/tokenize an input command...

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  • How can I solve the Log Pile wooden puzzle with a computer program?

    - by craig1410
    Can anyone suggest how to solve the Log Pile wooden puzzle using a computer program? See here to visualise the puzzle: http://www.puzzlethis.co.uk/products/madcow/the_log_pile.htm The picture only shows some of the pieces. The full set of 10 pieces are configured as follows with 1 representing a peg, -1 representing a hole and 0 representing neither a peg nor a hole. -1,1,0,-1,0 1,0,1,0,0 1,-1,1,0,0 -1,-1,0,0,-1 -1,1,0,1,0 0,1,0,0,1 1,0,-1,0,-1 0,-1,0,1,0 0,0,-1,1,-1 1,0,-1,0,0 The pieces can be interlocked in two layers of 5 pieces each with the top layer at 90 degrees to the bottom layer as shown in the above link. I have already created a solution to this problem myself using Java but I feel that it was a clumsy solution and I am interested to see some more sophisticated solutions. Feel free to either suggest a general approach or to provide a working program in the language of your choice. My approach was to use the numeric notation above to create an array of "Logs". I then used a combination/permutation generator to try all possible arrangements of the Logs until a solution was found where all the intersections equated to zero (ie. Peg to Hole, Hole to Peg or Blank to Blank). I used some speed-ups to detect the first failed intersection for a given permutation and move on to the next permutation. I hope you find this as interesting as I have. Thanks, Craig.

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  • Validating parameters according to a fixed reference

    - by James P.
    The following method is for setting the transfer type of an FTP connection. Basically, I'd like to validate the character input (see comments). Is this going overboard? Is there a more elegant approach? How do you approach parameter validation in general? Any comments are welcome. public void setTransferType(Character typeCharacter, Character optionalSecondCharacter) throws NumberFormatException, IOException { // http://www.nsftools.com/tips/RawFTP.htm#TYPE // Syntax: TYPE type-character [second-type-character] // // Sets the type of file to be transferred. type-character can be any // of: // // * A - ASCII text // * E - EBCDIC text // * I - image (binary data) // * L - local format // // For A and E, the second-type-character specifies how the text should // be interpreted. It can be: // // * N - Non-print (not destined for printing). This is the default if // second-type-character is omitted. // * T - Telnet format control (<CR>, <FF>, etc.) // * C - ASA Carriage Control // // For L, the second-type-character specifies the number of bits per // byte on the local system, and may not be omitted. final Set<Character> acceptedTypeCharacters = new HashSet<Character>(Arrays.asList( new Character[] {'A','E','I','L'} )); final Set<Character> acceptedOptionalSecondCharacters = new HashSet<Character>(Arrays.asList( new Character[] {'N','T','C'} )); if( acceptedTypeCharacters.contains(typeCharacter) ) { if( new Character('A').equals( typeCharacter ) || new Character('E').equals( typeCharacter ) ){ if( acceptedOptionalSecondCharacters.contains(optionalSecondCharacter) ) { executeCommand("TYPE " + typeCharacter + " " + optionalSecondCharacter ); } } else { executeCommand("TYPE " + typeCharacter ); } } }

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  • Contacts & Autocomplete

    - by Vince
    First post. I'm new to android and programming in general. What I'm attempting to is to have an autocomplete text box pop up with auto complete names from the contact list. IE, if they type in "john" it will say "John Smith" or any john in their contacts. The code is basic, I pulled it from a few tutorials. private void autoCompleteBox() { ContentResolver cr = getContentResolver(); Uri contacts = Uri.parse("content://contacts/people"); Cursor managedCursor1 = cr.query(contacts, null, null, null, null); if (managedCursor1.moveToFirst()) { String contactname; String cphoneNumber; int nameColumn = managedCursor1.getColumnIndex("name"); int phoneColumn = managedCursor1.getColumnIndex("number"); Log.d("int Name", Integer.toString(nameColumn)); Log.d("int Number", Integer.toString(phoneColumn)); do { // Get the field values contactname = managedCursor1.getString(nameColumn); cphoneNumber = managedCursor1.getString(phoneColumn); if ((contactname != " " || contactname != null) && (cphoneNumber != " " || cphoneNumber != null)) { c_Name.add(contactname); c_Number.add(cphoneNumber); Toast.makeText(this, contactname, Toast.LENGTH_SHORT) .show(); } } while (managedCursor1.moveToNext()); } name_Val = (String[]) c_Name.toArray(new String[c_Name.size()]); phone_Val = (String[]) c_Number.toArray(new String[c_Name.size()]); ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_dropdown_item_1line, name_Val); personName.setAdapter(adapter); } personName is my autocompletetextbox. So it actually works when I use it in the emulator (4.2) with manually entered contacts through the people app, but when I use it on my device, it will not pop up with any names. I'm sure it's something ridiculous but I've tried to find the answer and I'm getting nowhere. Can't learn if I don't ask.

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  • How to collect and inject all beans of a given type in Spring XML configuration

    - by GrzegorzOledzki
    One of the strongest accents of the Spring framework is the Dependency Injection concept. I understand one of the advices behind that is to separate general high-level mechanism from low-level details (as announced by Dependency Inversion Principle). Technically, that boils down to having a bean implementation to know as little as possible about a bean being injected as a dependency, e.g. public class PrintOutBean { private LogicBean logicBean; public void action() { System.out.println(logicBean.humanReadableDetails()); } //... } <bean class="PrintOutBean"> <property name="loginBean" ref="ShoppingCartBean"/> </bean> But what if I wanted to a have a high-level mechanism operating on multiple dependent beans? public class MenuManagementBean { private Collection<Option> options; public void printOut() { for (Option option:options) { // do something for option } //... } } I know one solution would be to use @Autowired annotation in the singleton bean, that is... @Autowired private Collection<Option> options; But doesn't it violate the separation principle? Why do I have to specify what dependents to take in the very same place I use them (i.e. MenuManagementBean class in my example)? Is there a way to inject collections of beans in the XML configuration like this (without any annotation in the MMB class)? <bean class="MenuManagementBean"> <property name="options"> <xxx:autowire by-type="MyOptionImpl"/> </property> </bean>

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  • BufferedImage.getGraphics() resulting in memory leak, is there a fix?

    - by user359202
    Hi friends, I'm having problem with some framework API calling BufferedImage.getGraphics() method and thus causing memory leak. What this method does is that it always calls BufferedImage.createGraphics(). On a windows machine, createGraphics() is handled by Win32GraphicsEnvironment which keeps a listeners list inside its field displayChanger. When I call getGraphics on my BufferedImage someChart, someChart's SurfaceManager(which retains a reference to someChart) is added to the listeners map in Win32GraphicsEnvironment, preventing someChart to be garbage collected. Nothing afterwards removes someChart's SurfaceManager from the listeners map. In general, the summarized path stopping a BufferedImage from being garbage collected, once getGraphics is called, is as follows: GC Root - localGraphicsEnvironment(Win32GraphicsEnvironment) - displayChanger(SunDisplayChanger) - listeners(Map) - key(D3DChachingSurfaceManager) - bImg(BufferedImage) I could have changed the framework's code so that after every called to BufferedImage.getGraphics(), I keep a reference to the BufferedImage's SurfaceManager. Then, I get hold of localGraphicsEnvironment, cast it to Win32GraphicsEnvironment, then call removeDisplayChangedListener() using the reference to the BufferedImage's SurfaceManager. But I don't think this is a proper way to solve the problem. Could someone please help me with this issue? Thanks a lot!

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  • Expose webservice directly to webclients or keep a thin server-side script layer in between?

    - by max
    Hi, I'm developing a REST webservice (Java, Jersey). The people I'm doing this for want to directly access the webservice via Javascript. Some instinct tells me this is not a good idea, but I cannot really explain that instinct. My natural approach would have been to have the webservice do the real logic and database access, but also have some (relatively thin) server-side script layer (e.g. in PHP). Clients would talk to the PHP layer which in turn would talk to the webservice. (The webservice would be pretty local to the apache/PHP server and implicitly trust calls from the script layer. The script layer would take care of session management.) (Btw, I am not talking about just hiding the webservice behind an Apache which simply redirects calls.) But as I find myself at a lack of words/arguments to explain my instinct, I wonder whether my instinct is right - note that while I have been developing all kinds of software in all kinds of languages and frameworks for like 17 years, this is the first time I develop a webservice. So my question is basically: what are your opinions? Are there any standard setups? Is my instinct totally wrong? Or partially? ;P Many thanks, Max PS: I might add a few bits of information about the planned usage of the whole application: will be accessed by different kinds of users, partly general public, partly privileged thus, all major OS/browser combinations can be expected as clients however, writing the client is not my responsibility will potentially have very high load/traffic logic of webservice will later be massively expanded for another product which is basically a superset of the functionality of the current project there is a significant likelihood that at some point an API should be exposed which can be used by 3rd party developers - obviously, with some restrictions at some point, the public view of the product should become accessible via smartphones, too (in other words, maybe a customized version of the site to adapt to the smaller display and different input methods)

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  • Does Socket open another thread? Does it return something?

    - by Roman
    In the client application I call new Socket(serverIP,serverPort). As a result the client application sends a request to the server application to open a socket. Does it start a new thread? I mean which of the following is true? Client application sends a request and immediately starts to execute following commands (not weighting for the answer). Client sends the request and weights for the answer. As soon as the answer is obtained, the client application continues to execute following commands. The second case seems to be more realistic and logical for me. However, I do not understand what happens if the server does not open a socket and it does not say that it does not "want" to open the second (it can happen if the server does not exist or network is broken). What will happen in this case? Will server weight forever? In general it would be nice for the client to know what is the result of its request for the socket. For example I can imagine the following situations: The socket is opened by the server. The server refuses to open a socket. So, server exists, it got the request from the client but it says "no". There is no response from the server. I know that new Socket(serverIP,serverPort) does not "return" this kind of information. But it throws exceptions. One of them is "UnkownHostException". When it is thrown? When the server is not responding for a while (for how long)? ADDED: I just found out that UnknownHostException is thrown to indicate that the IP address of a host could not be determined. So, it is unrelated with the above described situations (server is not responding, server refuses to open a socket).

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  • Which one gives you more advantages: Microsoft or SUN/Oracle certification?

    - by edwin.nathaniel
    Which one gives you more advantages: Microsoft or SUN/Oracle certification? If you don't mind, please relate your answer to your career (dev, sys-admin, dba), industry (finance, general consulting, business apps, software house), and location (where you live, does it influence your decision?) as well. One reason I asked this because I heard that having MCP (in C#, MCSAD or whatever the cert is called these days) could give you extra point from the employer perspective if they're a Microsoft Partner. I don't quite understand why and am also wondering if SUN/Oracle certificate holder have similar edge/benefit. I'm also interested to know if Certification plays role where you live. For example: certification could be a big negative sign in Silicon Valley, but might be helpful if you're in other US/Canada cities or outside USA/Canada. If you are an independent software consultant, do these certification helps you win bids? I totally understand that this question might be subjective and could be "closed". But it doesn't hurt to ask I suppose. I also understand that there are people who dislike/disagree (or have negative perspective on technology certification). While there are people who have the opinion that "these are not the kind of employers you would want to work with", I respect you guys, but sometime a pure software product company might not exist in certain cities in the world. And if certification can help one's career somewhere else, I guess that means more opportunities right? I've had experienced in both platforms: (short) .NET and (not too long) Java (minus Oracle DB stuff), but I think it's about time I have to pick one of them and be good at. Where I live right now might also dictates my career albeit insignificant. Anyhow, this last paragraph is just tiny blurb. Thanks!

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  • DDNS Not Creating Journal (Dhcpd and Named)

    - by user130094
    * EDIT 1 * After monkeying with additional debug logging I see some log entries of interest. 27-Jul-2012 23:45:26.537 general: error: zone example.lan/IN/internal: journal rollforward failed: no more 27-Jul-2012 23:45:26.537 general: error: zone example.lan/IN/internal: not loaded due to errors. ^^^ If I can remedy the above messages I think I'll be good to go ^^^ * EDIT 2 * Grasping at straws I touched a forward and a reverse zone journal file and restarted named. Boom! Works. Despite documentation stating the files are created automatically and what I have seen before... dunno why but that did the trick. Also re-checked perms on the dir the files live in. As certain as I was, they were correct with named having rw. CentOS 6 (final) dhcpd 4.1.1-P1 named BIND 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6 Basic DHCP and DNS functionality are in place on 192.168.111.2. Clients are assigned addresses as intended and can resolve local DNS names as well as Internet names. My problem is that named's zone journal files are not created. chroot: /var/named/chroot I tried placing the zone files in various directories (/var/named/data, /var/named, /var/named/dynamic - no matter which dir with named owning and wide open perms I now get nowhere). Along the way I, at one point, got a permission denied when named tried to create the journal. Resolved the issue by: chown --recursive named:named /var/named chmod --recursive 777 /var/named The journal was then created and here's where things fell apart. I attempted to tame permissions to something more sane and broke it. Once changed and having restarted named it threw an error indicating the journal was out of sync (or something to that affect)... didn't matter since this is a new setup so I deleted it and now it is not recreated. Now though I see no errors in /var/log/messages, my chrooted /var/log/named.log, or chrooted /var/log/named.debug. I increased the debug level with 'rndc trace' - no love. Increased trace to 10, still nothing. SELinux is disabled... [root@server temp]# sestatus SELinux status: disabled dhcpd.conf... allow client-updates; ddns-update-style interim; subnet 192.168.111.0 netmask 255.255.255.224 { ... key dhcpudpate { algorithm hmac-md5; secret LDJMdPdEZED+/nN/AGO9ZA==; } zone example.lan. { primary 192.168.111.2; key dhcpudpate; } } named.conf... key dhcpudpate { algorithm hmac-md5; secret "LDJMdPdEZED+/nN/AGO9ZA=="; }; zone "example.lan" { type master; file "/var/named/dynamic/example.lan.db"; allow-transfer { none; }; allow-update { key dhcpudpate; }; notify false; check-names ignore; }; The following shows /var/log/named.log output of named starting up - no errors. 27-Jul-2012 21:33:39.349 general: info: zone 111.168.192.in-addr.arpa/IN/internal: loaded serial 2012072601 27-Jul-2012 21:33:39.349 general: info: zone example.lan/IN/internal: loaded serial 2012072501 27-Jul-2012 21:33:39.350 general: info: zone example2.lan/IN/internal: loaded serial 2012072501 27-Jul-2012 21:33:39.350 general: info: zone example3.lan/IN/internal: loaded serial 2012072601 27-Jul-2012 21:33:39.350 general: info: zone example4.lan/IN/internal: loaded serial 2012072501 27-Jul-2012 21:33:39.351 general: info: zone example5.lan/IN/internal: loaded serial 2012072501 27-Jul-2012 21:33:39.351 general: info: managed-keys-zone ./IN/internal: loaded serial 0 27-Jul-2012 21:33:39.351 general: info: zone example.lan/IN/external: loaded serial 2012072501 27-Jul-2012 21:33:39.352 general: info: zone example1.lan/IN/external: loaded serial 2012072501 27-Jul-2012 21:33:39.352 general: info: zone example2.lan/IN/external: loaded serial 2012072501 27-Jul-2012 21:33:39.352 general: info: zone example3.lan/IN/external: loaded serial 2012072501 27-Jul-2012 21:33:39.353 general: info: managed-keys-zone ./IN/external: loaded serial 0 27-Jul-2012 21:33:39.353 general: notice: running 27-Jul-2012 21:34:03.825 general: info: received control channel command 'trace 10' 27-Jul-2012 21:34:03.825 general: info: debug level is now 10 ...and /var/log/messages for a named start... Jul 27 23:02:04 server named[9124]: ---------------------------------------------------- Jul 27 23:02:04 server named[9124]: BIND 9 is maintained by Internet Systems Consortium, Jul 27 23:02:04 server named[9124]: Inc. (ISC), a non-profit 501(c)(3) public-benefit Jul 27 23:02:04 server named[9124]: corporation. Support and training for BIND 9 are Jul 27 23:02:04 server named[9124]: available at https://www.isc.org/support Jul 27 23:02:04 server named[9124]: ---------------------------------------------------- Jul 27 23:02:04 server named[9124]: adjusted limit on open files from 4096 to 1048576 Jul 27 23:02:04 server named[9124]: found 2 CPUs, using 2 worker threads Jul 27 23:02:04 server named[9124]: using up to 4096 sockets Jul 27 23:02:04 server named[9124]: loading configuration from '/etc/named.conf' Jul 27 23:02:04 server named[9124]: using default UDP/IPv4 port range: [1024, 65535] Jul 27 23:02:04 server named[9124]: using default UDP/IPv6 port range: [1024, 65535] Jul 27 23:02:04 server named[9124]: listening on IPv4 interface eth0, 192.168.111.2#53 Jul 27 23:02:04 server named[9124]: generating session key for dynamic DNS Jul 27 23:02:04 server named[9124]: sizing zone task pool based on 12 zones Jul 27 23:02:04 server named[9124]: set up managed keys zone for view internal, file 'dynamic/3bed2cb3a3acf7b6a8ef408420cc682d5520e26976d354254f528c965612054f.mkeys' Jul 27 23:02:04 server named[9124]: set up managed keys zone for view external, file 'dynamic/3c4623849a49a53911c4a3e48d8cead8a1858960bccdea7a1b978d73ec2f06d7.mkeys' Jul 27 23:02:04 server named[9124]: command channel listening on 127.0.0.1#953 What can I do to troubleshoot this further? It almost seems as though dhcpd is not triggering the update. Maybe I should troubleshoot here and, if so, how? Many thanks.

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  • Optimizing a lot of Scanner.findWithinHorizon(pattern, 0) calls

    - by darvids0n
    I'm building a process which extracts data from 6 csv-style files and two poorly laid out .txt reports and builds output CSVs, and I'm fully aware that there's going to be some overhead searching through all that whitespace thousands of times, but I never anticipated converting about about 50,000 records would take 12 hours. Excerpt of my manual matching code (I know it's horrible that I use lists of tokens like that, but it was the best thing I could think of): public static String lookup(List<String> tokensBefore, List<String> tokensAfter) { String result = null; while(_match(tokensBefore)) { // block until all input is read if(id.hasNext()) { result = id.next(); // capture the next token that matches if(_matchImmediate(tokensAfter)) // try to match tokensAfter to this result return result; } else return null; // end of file; no match } return null; // no matches } private static boolean _match(List<String> tokens) { return _match(tokens, true); } private static boolean _match(List<String> tokens, boolean block) { if(tokens != null && !tokens.isEmpty()) { if(id.findWithinHorizon(tokens.get(0), 0) == null) return false; for(int i = 1; i <= tokens.size(); i++) { if (i == tokens.size()) { // matches all tokens return true; } else if(id.hasNext() && !id.next().matches(tokens.get(i))) { break; // break to blocking behaviour } } } else { return true; // empty list always matches } if(block) return _match(tokens); // loop until we find something or nothing else return false; // return after just one attempted match } private static boolean _matchImmediate(List<String> tokens) { if(tokens != null) { for(int i = 0; i <= tokens.size(); i++) { if (i == tokens.size()) { // matches all tokens return true; } else if(!id.hasNext() || !id.next().matches(tokens.get(i))) { return false; // doesn't match, or end of file } } return false; // we have some serious problems if this ever gets called } else { return true; // empty list always matches } } Basically wondering how I would work in an efficient string search (Boyer-Moore or similar). My Scanner id is scanning a java.util.String, figured buffering it to memory would reduce I/O since the search here is being performed thousands of times on a relatively small file. The performance increase compared to scanning a BufferedReader(FileReader(File)) was probably less than 1%, the process still looks to be taking a LONG time. I've also traced execution and the slowness of my overall conversion process is definitely between the first and last like of the lookup method. In fact, so much so that I ran a shortcut process to count the number of occurrences of various identifiers in the .csv-style files (I use 2 lookup methods, this is just one of them) and the process completed indexing approx 4 different identifiers for 50,000 records in less than a minute. Compared to 12 hours, that's instant. Some notes (updated): I don't necessarily need the pattern-matching behaviour, I only get the first field of a line of text so I need to match line breaks or use Scanner.nextLine(). All ID numbers I need start at position 0 of a line and run through til the first block of whitespace, after which is the name of the corresponding object. I would ideally want to return a String, not an int locating the line number or start position of the result, but if it's faster then it will still work just fine. If an int is being returned, however, then I would now have to seek to that line again just to get the ID; storing the ID of every line that is searched sounds like a way around that. Anything to help me out, even if it saves 1ms per search, will help, so all input is appreciated. Thankyou! Usage scenario 1: I have a list of objects in file A, who in the old-style system have an id number which is not in file A. It is, however, POSSIBLY in another csv-style file (file B) or possibly still in a .txt report (file C) which each also contain a bunch of other information which is not useful here, and so file B needs to be searched through for the object's full name (1 token since it would reside within the second column of any given line), and then the first column should be the ID number. If that doesn't work, we then have to split the search token by whitespace into separate tokens before doing a search of file C for those tokens as well. Generalised code: String field; for (/* each record in file A */) { /* construct the rest of this object from file A info */ // now to find the ID, if we can List<String> objectName = new ArrayList<String>(1); objectName.add(Pattern.quote(thisObject.fullName)); field = lookup(objectSearchToken, objectName); // search file B if(field == null) // not found in file B { lookupReset(false); // initialise scanner to check file C objectName.clear(); // not using the full name String[] tokens = thisObject.fullName.split(id.delimiter().pattern()); for(String s : tokens) objectName.add(Pattern.quote(s)); field = lookup(objectSearchToken, objectName); // search file C lookupReset(true); // back to file B } else { /* found it, file B specific processing here */ } if(field != null) // found it in B or C thisObject.ID = field; } The objectName tokens are all uppercase words with possible hyphens or apostrophes in them, separated by spaces. Much like a person's name. As per a comment, I will pre-compile the regex for my objectSearchToken, which is just [\r\n]+. What's ending up happening in file C is, every single line is being checked, even the 95% of lines which don't contain an ID number and object name at the start. Would it be quicker to use ^[\r\n]+.*(objectname) instead of two separate regexes? It may reduce the number of _match executions. The more general case of that would be, concatenate all tokensBefore with all tokensAfter, and put a .* in the middle. It would need to be matching backwards through the file though, otherwise it would match the correct line but with a huge .* block in the middle with lots of lines. The above situation could be resolved if I could get java.util.Scanner to return the token previous to the current one after a call to findWithinHorizon. I have another usage scenario. Will put it up asap.

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  • .exe is not created when using launch4j and maven

    - by Ismail Sen
    I'm trying to create an exe file for my JAVA project using launch4j and Maven. Here is my pom.xml <build> <pluginManagement> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.0</version> <configuration> <source>1.7</source> <target>1.7</target> </configuration> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-jar-plugin</artifactId> <version>2.3.2</version> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-assembly-plugin</artifactId> <version>2.4</version> <configuration> <descriptorRefs> <descriptortRef>jar-with-dependencies</descriptortRef> </descriptorRefs> <archive> <manifest> <mainClass>dev.main.App</mainClass> </manifest> </archive> </configuration> <executions> <execution> <id>make-assembly</id> <phase>package</phase> <goals> <goal>single</goal> </goals> </execution> </executions> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-shade-plugin</artifactId> <version>1.7.1</version> <executions> <execution> <phase>package</phase> <goals> <goal>shade</goal> </goals> </execution> </executions> <configuration> <shadedArtifactAttached>true</shadedArtifactAttached> <shadedClassifierName>shaded</shadedClassifierName> <transformers> <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer"> <mainClass>dev.main.App</mainClass> </transformer> </transformers> </configuration> </plugin> <plugin> <groupId>com.akathist.maven.plugins.launch4j</groupId> <artifactId>launch4j-maven-plugin</artifactId> <version>1.5.1</version> <executions> <execution> <id>l4j-clui</id> <phase>package</phase> <goals> <goal>launch4j</goal> </goals> <configuration> <headerType>console</headerType> <jar>${project.build.directory}/target/App-jar-with-dependencies.jar</jar> <outfile>${project.build.directory}/target/App.exe</outfile> <downloadUrl>http://java.com/download</downloadUrl> <classPath> <mainClass>dev.main.App</mainClass> </classPath> <jre> <minVersion>1.6.0</minVersion> <jdkPreference>preferJre</jdkPreference> </jre> <versionInfo> <fileVersion>1.0.0.0</fileVersion> <txtFileVersion>${project.version}</txtFileVersion> <fileDescription>${project.name}</fileDescription> <copyright>C</copyright> <productVersion>1.0.0.0</productVersion> <txtProductVersion>1.0.0.0</txtProductVersion> <productName>${project.name}</productName> <internalName>AppName</internalName> <originalFilename>App.exe</originalFilename> </versionInfo> </configuration> </execution> </executions> </plugin> </plugins> </pluginManagement> </build> I run : mvn clean compile assembly:single to create my jar app with all Maven dependencies. To create the .exe I do : mvn package but nothing is created under target folder. Am I missing a goal or a configuration ? Ismail

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  • migrating Solaris to RH: network latency issue, tcp window size & other tcp parameters

    - by Bastien
    Hello I have a client/server app (Java) that I'm migrating from Solaris to RH Linux. since I started running it in RH, I noticed some issues related to latency. I managed to isolate the problem that looks like this: client sends 5 messages (32 bytes each) in a row (same application timestamp) to the server. server echos messages. client receives replies and prints round trip time for each msg. in Solaris, all is well: I get ALL 5 replies at the same time, roughly 80ms after having sent original messages (client & server are several thousands miles away from each other: my ping RTT is 80ms, all normal). in RH, first 3 messages are echoed normally (they arrive 80ms after they've been sent), however the following 2 arrive 80ms later (so total 160ms RTT). the pattern is always the same. clearly looked like a TCP problem. on my solaris box, I had previously configured the tcp stack with 2 specific options: disable nagle algorithm globally set tcp_deferred_acks_max to 0 on RH, it's not possible to disable nagle globally, but I disabled it on all of my apps' sockets (TCP_NODELAY). so I started playing with tcpdump (on the server machine), and compared both outputs: SOLARIS: 22 2.085645 client server TCP 56150 > 6006 [PSH, ACK] Seq=111 Ack=106 Win=66672 Len=22 "MSG_1 RCV" 23 2.085680 server client TCP 6006 > 56150 [ACK] Seq=106 Ack=133 Win=50400 Len=0 24 2.085908 client server TCP 56150 > 6006 [PSH, ACK] Seq=133 Ack=106 Win=66672 Len=22 "MSG_2 RCV" 25 2.085925 server client TCP 6006 > 56150 [ACK] Seq=106 Ack=155 Win=50400 Len=0 26 2.086175 client server TCP 56150 > 6006 [PSH, ACK] Seq=155 Ack=106 Win=66672 Len=22 "MSG_3 RCV" 27 2.086192 server client TCP 6006 > 56150 [ACK] Seq=106 Ack=177 Win=50400 Len=0 28 2.086243 server client TCP 6006 > 56150 [PSH, ACK] Seq=106 Ack=177 Win=50400 Len=21 "MSG_1 ECHO" 29 2.086440 client server TCP 56150 > 6006 [PSH, ACK] Seq=177 Ack=106 Win=66672 Len=22 "MSG_4 RCV" 30 2.086454 server client TCP 6006 > 56150 [ACK] Seq=127 Ack=199 Win=50400 Len=0 31 2.086659 server client TCP 6006 > 56150 [PSH, ACK] Seq=127 Ack=199 Win=50400 Len=21 "MSG_2 ECHO" 32 2.086708 client server TCP 56150 > 6006 [PSH, ACK] Seq=199 Ack=106 Win=66672 Len=22 "MSG_5 RCV" 33 2.086721 server client TCP 6006 > 56150 [ACK] Seq=148 Ack=221 Win=50400 Len=0 34 2.086947 server client TCP 6006 > 56150 [PSH, ACK] Seq=148 Ack=221 Win=50400 Len=21 "MSG_3 ECHO" 35 2.087196 server client TCP 6006 > 56150 [PSH, ACK] Seq=169 Ack=221 Win=50400 Len=21 "MSG_4 ECHO" 36 2.087500 server client TCP 6006 > 56150 [PSH, ACK] Seq=190 Ack=221 Win=50400 Len=21 "MSG_5 ECHO" 37 2.165390 client server TCP 56150 > 6006 [ACK] Seq=221 Ack=148 Win=66632 Len=0 38 2.166314 client server TCP 56150 > 6006 [ACK] Seq=221 Ack=190 Win=66588 Len=0 39 2.364135 client server TCP 56150 > 6006 [ACK] Seq=221 Ack=211 Win=66568 Len=0 REDHAT: 17 2.081163 client server TCP 55879 > 6006 [PSH, ACK] Seq=111 Ack=106 Win=66672 Len=22 "MSG_1 RCV" 18 2.081178 server client TCP 6006 > 55879 [ACK] Seq=106 Ack=133 Win=5888 Len=0 19 2.081297 server client TCP 6006 > 55879 [PSH, ACK] Seq=106 Ack=133 Win=5888 Len=21 "MSG_1 ECHO" 20 2.081711 client server TCP 55879 > 6006 [PSH, ACK] Seq=133 Ack=106 Win=66672 Len=22 "MSG_2 RCV" 21 2.081761 client server TCP 55879 > 6006 [PSH, ACK] Seq=155 Ack=106 Win=66672 Len=22 "MSG_3 RCV" 22 2.081846 server client TCP 6006 > 55879 [PSH, ACK] Seq=127 Ack=177 Win=5888 Len=21 "MSG_2 ECHO" 23 2.081995 server client TCP 6006 > 55879 [PSH, ACK] Seq=148 Ack=177 Win=5888 Len=21 "MSG_3 ECHO" 24 2.082011 client server TCP 55879 > 6006 [PSH, ACK] Seq=177 Ack=106 Win=66672 Len=22 "MSG_4 RCV" 25 2.082362 client server TCP 55879 > 6006 [PSH, ACK] Seq=199 Ack=106 Win=66672 Len=22 "MSG_5 RCV" 26 2.082377 server client TCP 6006 > 55879 [ACK] Seq=169 Ack=221 Win=5888 Len=0 27 2.171003 client server TCP 55879 > 6006 [ACK] Seq=221 Ack=148 Win=66632 Len=0 28 2.171019 server client TCP 6006 > 55879 [PSH, ACK] Seq=169 Ack=221 Win=5888 Len=42 "MSG_4 ECHO + MSG_5 ECHO" 29 2.257498 client server TCP 55879 > 6006 [ACK] Seq=221 Ack=211 Win=66568 Len=0 so, I got confirmation things are not working correctly for RH: packet 28 is sent TOO LATE, it looks like the server is waiting for packet 27's ACK before doing anything. seems to me it's the most likely reason... then I realized that the "Win" parameters are different on Solaris & RH dumps: 50400 on Solaris, only 5888 on RH. that's another hint... I read the doc about the slide window & buffer window, and played around with the rcvBuffer & sendBuffer in java on my sockets, but never managed to change this 5888 value to anything else (I checked each time directly with tcpdump). does anybody know how to do this ? I'm having a hard time getting definitive information, as in some cases there's "auto-negotiation" that I might need to bypass, etc... I eventually managed to get only partially rid of my initial problem by setting the "tcp_slow_start_after_idle" parameter to 0 on RH, but it did not change the "win" parameter at all. the same problem was there for the first 4 groups of 5 messages, with TCP retransmission & TCP Dup ACK in tcpdump, then the problem disappeared altogether for all following groups of 5 messages. It doesn't seem like a very clean and/or generic solution to me. I'd really like to reproduce the exact same conditions under both OSes. I'll keep researching, but any help from TCP gurus would be greatly appreciated ! thanks !

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  • How to connect to bluetoothbee device using j2me?

    - by user1500412
    I developed a simple bluetooth connection application in j2me. I try it on emulator, both server and client can found each other, but when I deploy the application to blackberry mobile phone and connect to a bluetoothbee device it says service search no records. What could it be possibly wrong? is it j2me can not find a service in bluetoothbee? The j2me itself succeed to found the bluetoothbee device, but why it can not find the service? My code is below. What I don't understand is the UUID? how to set UUID for unknown source? since I didn't know the UUID for the bluetoothbee device. class SearchingDevice extends Canvas implements Runnable,CommandListener,DiscoveryListener{ //...... public SearchingDevice(MenuUtama midlet, Display display){ this.display = display; this.midlet = midlet; t = new Thread(this); t.start(); timer = new Timer(); task = new TestTimerTask(); /*--------------------Device List------------------------------*/ select = new Command("Pilih",Command.OK,0); back = new Command("Kembali",Command.BACK,0); btDevice = new List("Pilih Device",Choice.IMPLICIT); btDevice.addCommand(select); btDevice.addCommand(back); btDevice.setCommandListener(this); /*------------------Input Form---------------------------------*/ formInput = new Form("Form Input"); nama = new TextField("Nama","",50,TextField.ANY); umur = new TextField("Umur","",50,TextField.ANY); measure = new Command("Ukur",Command.SCREEN,0); gender = new ChoiceGroup("Jenis Kelamin",Choice.EXCLUSIVE); formInput.addCommand(back); formInput.addCommand(measure); gender.append("Pria", null); gender.append("Wanita", null); formInput.append(nama); formInput.append(umur); formInput.append(gender); formInput.setCommandListener(this); /*---------------------------------------------------------------*/ findDevice(); } /*----------------Gambar screen searching device---------------------------------*/ protected void paint(Graphics g) { g.setColor(0,0,0); g.fillRect(0, 0, getWidth(), getHeight()); g.setColor(255,255,255); g.drawString("Mencari Device", 20, 20, Graphics.TOP|Graphics.LEFT); if(this.counter == 1){ g.setColor(255,115,200); g.fillRect(20, 100, 20, 20); } if(this.counter == 2){ g.setColor(255,115,200); g.fillRect(20, 100, 20, 20); g.setColor(100,255,255); g.fillRect(60, 80, 20, 40); } if(this.counter == 3){ g.setColor(255,115,200); g.fillRect(20, 100, 20, 20); g.setColor(100,255,255); g.fillRect(60, 80, 20, 40); g.setColor(255,115,200); g.fillRect(100, 60, 20, 60); } if(this.counter == 4){ g.setColor(255,115,200); g.fillRect(20, 100, 20, 20); g.setColor(100,255,255); g.fillRect(60, 80, 20, 40); g.setColor(255,115,200); g.fillRect(100, 60, 20, 60); g.setColor(100,255,255); g.fillRect(140, 40, 20, 80); //display.callSerially(this); } } /*--------- Running Searching Screen ----------------------------------------------*/ public void run() { while(run){ this.counter++; if(counter > 4){ this.counter = 1; } try { Thread.sleep(1000); } catch (InterruptedException ex) { System.out.println("interrupt"+ex.getMessage()); } repaint(); } } /*-----------------------------cari device bluetooth yang -------------------*/ public void findDevice(){ try { devices = new java.util.Vector(); local = LocalDevice.getLocalDevice(); agent = local.getDiscoveryAgent(); local.setDiscoverable(DiscoveryAgent.GIAC); agent.startInquiry(DiscoveryAgent.GIAC, this); } catch (BluetoothStateException ex) { System.out.println("find device"+ex.getMessage()); } } /*-----------------------------jika device ditemukan--------------------------*/ public void deviceDiscovered(RemoteDevice rd, DeviceClass dc) { devices.addElement(rd); } /*--------------Selesai tes koneksi ke bluetooth server--------------------------*/ public void inquiryCompleted(int param) { switch(param){ case DiscoveryListener.INQUIRY_COMPLETED: //inquiry completed normally if(devices.size()>0){ //at least one device has been found services = new java.util.Vector(); this.findServices((RemoteDevice)devices.elementAt(0)); this.run = false; do_alert("Inquiry completed",4000); }else{ do_alert("No device found in range",4000); } break; case DiscoveryListener.INQUIRY_ERROR: do_alert("Inquiry error",4000); break; case DiscoveryListener.INQUIRY_TERMINATED: do_alert("Inquiry canceled",4000); break; } } /*-------------------------------Cari service bluetooth server----------------------------*/ public void findServices(RemoteDevice device){ try { // int[] attributes = {0x100,0x101,0x102}; UUID[] uuids = new UUID[1]; //alamat server uuids[0] = new UUID("F0E0D0C0B0A000908070605040302010",false); //uuids[0] = new UUID("8841",true); //menyiapkan device lokal local = LocalDevice.getLocalDevice(); agent = local.getDiscoveryAgent(); //mencari service dari server agent.searchServices(null, uuids, device, this); //server = (StreamConnectionNotifies)Connector.open(url.toString()); } catch (BluetoothStateException ex) { // ex.printStackTrace(); System.out.println("Errorx"+ex.getMessage()); } } /*---------------------------Pencarian service selesai------------------------*/ public void serviceSearchCompleted(int transID, int respCode) { switch(respCode){ case DiscoveryListener.SERVICE_SEARCH_COMPLETED: if(currentDevice == devices.size() - 1){ if(services.size() > 0){ this.run = false; display.setCurrent(btDevice); do_alert("Service found",4000); }else{ do_alert("The service was not found",4000); } }else{ currentDevice++; this.findServices((RemoteDevice)devices.elementAt(currentDevice)); } break; case DiscoveryListener.SERVICE_SEARCH_DEVICE_NOT_REACHABLE: do_alert("Device not Reachable",4000); break; case DiscoveryListener.SERVICE_SEARCH_ERROR: do_alert("Service search error",4000); break; case DiscoveryListener.SERVICE_SEARCH_NO_RECORDS: do_alert("No records return",4000); break; case DiscoveryListener.SERVICE_SEARCH_TERMINATED: do_alert("Inquiry canceled",4000); break; } } public void servicesDiscovered(int i, ServiceRecord[] srs) { for(int x=0; x<srs.length;x++) services.addElement(srs[x]); try { btDevice.append(((RemoteDevice)devices.elementAt(currentDevice)).getFriendlyName(false),null); } catch (IOException ex) { System.out.println("service discover"+ex.getMessage()); } } public void do_alert(String msg, int time_out){ if(display.getCurrent() instanceof Alert){ ((Alert)display.getCurrent()).setString(msg); ((Alert)display.getCurrent()).setTimeout(time_out); }else{ Alert alert = new Alert("Bluetooth"); alert.setString(msg); alert.setTimeout(time_out); display.setCurrent(alert); } } private String getData(){ System.out.println("getData"); String cmd=""; try { ServiceRecord service = (ServiceRecord)services.elementAt(btDevice.getSelectedIndex()); String url = service.getConnectionURL(ServiceRecord.NOAUTHENTICATE_NOENCRYPT, false); conn = (StreamConnection)Connector.open(url); DataInputStream in = conn.openDataInputStream(); int i=0; timer.schedule(task, 15000); char c1; while(time){ //while(((c1 = in.readChar())>0) && (c1 != '\n')){ //while(((c1 = in.readChar())>0) ){ c1 = in.readChar(); cmd = cmd + c1; //System.out.println(c1); // } } System.out.print("cmd"+cmd); if(time == false){ in.close(); conn.close(); } } catch (IOException ex) { System.err.println("Cant read data"+ex); } return cmd; } //timer task fungsinya ketika telah mencapai waktu yg dijadwalkan putus koneksi private static class TestTimerTask extends TimerTask{ public TestTimerTask() { } public void run() { time = false; } } }

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  • Traditional IO vs memory-mapped

    - by Senne
    I'm trying to illustrate the difference in performance between traditional IO and memory mapped files in java to students. I found an example somewhere on internet but not everything is clear to me, I don't even think all steps are nececery. I read a lot about it here and there but I'm not convinced about a correct implementation of neither of them. The code I try to understand is: public class FileCopy{ public static void main(String args[]){ if (args.length < 1){ System.out.println(" Wrong usage!"); System.out.println(" Correct usage is : java FileCopy <large file with full path>"); System.exit(0); } String inFileName = args[0]; File inFile = new File(inFileName); if (inFile.exists() != true){ System.out.println(inFileName + " does not exist!"); System.exit(0); } try{ new FileCopy().memoryMappedCopy(inFileName, inFileName+".new" ); new FileCopy().customBufferedCopy(inFileName, inFileName+".new1"); }catch(FileNotFoundException fne){ fne.printStackTrace(); }catch(IOException ioe){ ioe.printStackTrace(); }catch (Exception e){ e.printStackTrace(); } } public void memoryMappedCopy(String fromFile, String toFile ) throws Exception{ long timeIn = new Date().getTime(); // read input file RandomAccessFile rafIn = new RandomAccessFile(fromFile, "rw"); FileChannel fcIn = rafIn.getChannel(); ByteBuffer byteBuffIn = fcIn.map(FileChannel.MapMode.READ_WRITE, 0,(int) fcIn.size()); fcIn.read(byteBuffIn); byteBuffIn.flip(); RandomAccessFile rafOut = new RandomAccessFile(toFile, "rw"); FileChannel fcOut = rafOut.getChannel(); ByteBuffer writeMap = fcOut.map(FileChannel.MapMode.READ_WRITE,0,(int) fcIn.size()); writeMap.put(byteBuffIn); long timeOut = new Date().getTime(); System.out.println("Memory mapped copy Time for a file of size :" + (int) fcIn.size() +" is "+(timeOut-timeIn)); fcOut.close(); fcIn.close(); } static final int CHUNK_SIZE = 100000; static final char[] inChars = new char[CHUNK_SIZE]; public static void customBufferedCopy(String fromFile, String toFile) throws IOException{ long timeIn = new Date().getTime(); Reader in = new FileReader(fromFile); Writer out = new FileWriter(toFile); while (true) { synchronized (inChars) { int amountRead = in.read(inChars); if (amountRead == -1) { break; } out.write(inChars, 0, amountRead); } } long timeOut = new Date().getTime(); System.out.println("Custom buffered copy Time for a file of size :" + (int) new File(fromFile).length() +" is "+(timeOut-timeIn)); in.close(); out.close(); } } When exactly is it nececary to use RandomAccessFile? Here it is used to read and write in the memoryMappedCopy, is it actually nececary just to copy a file at all? Or is it a part of memorry mapping? In customBufferedCopy, why is synchronized used here? I also found a different example that -should- test the performance between the 2: public class MappedIO { private static int numOfInts = 4000000; private static int numOfUbuffInts = 200000; private abstract static class Tester { private String name; public Tester(String name) { this.name = name; } public long runTest() { System.out.print(name + ": "); try { long startTime = System.currentTimeMillis(); test(); long endTime = System.currentTimeMillis(); return (endTime - startTime); } catch (IOException e) { throw new RuntimeException(e); } } public abstract void test() throws IOException; } private static Tester[] tests = { new Tester("Stream Write") { public void test() throws IOException { DataOutputStream dos = new DataOutputStream( new BufferedOutputStream( new FileOutputStream(new File("temp.tmp")))); for(int i = 0; i < numOfInts; i++) dos.writeInt(i); dos.close(); } }, new Tester("Mapped Write") { public void test() throws IOException { FileChannel fc = new RandomAccessFile("temp.tmp", "rw") .getChannel(); IntBuffer ib = fc.map( FileChannel.MapMode.READ_WRITE, 0, fc.size()) .asIntBuffer(); for(int i = 0; i < numOfInts; i++) ib.put(i); fc.close(); } }, new Tester("Stream Read") { public void test() throws IOException { DataInputStream dis = new DataInputStream( new BufferedInputStream( new FileInputStream("temp.tmp"))); for(int i = 0; i < numOfInts; i++) dis.readInt(); dis.close(); } }, new Tester("Mapped Read") { public void test() throws IOException { FileChannel fc = new FileInputStream( new File("temp.tmp")).getChannel(); IntBuffer ib = fc.map( FileChannel.MapMode.READ_ONLY, 0, fc.size()) .asIntBuffer(); while(ib.hasRemaining()) ib.get(); fc.close(); } }, new Tester("Stream Read/Write") { public void test() throws IOException { RandomAccessFile raf = new RandomAccessFile( new File("temp.tmp"), "rw"); raf.writeInt(1); for(int i = 0; i < numOfUbuffInts; i++) { raf.seek(raf.length() - 4); raf.writeInt(raf.readInt()); } raf.close(); } }, new Tester("Mapped Read/Write") { public void test() throws IOException { FileChannel fc = new RandomAccessFile( new File("temp.tmp"), "rw").getChannel(); IntBuffer ib = fc.map( FileChannel.MapMode.READ_WRITE, 0, fc.size()) .asIntBuffer(); ib.put(0); for(int i = 1; i < numOfUbuffInts; i++) ib.put(ib.get(i - 1)); fc.close(); } } }; public static void main(String[] args) { for(int i = 0; i < tests.length; i++) System.out.println(tests[i].runTest()); } } I more or less see whats going on, my output looks like this: Stream Write: 653 Mapped Write: 51 Stream Read: 651 Mapped Read: 40 Stream Read/Write: 14481 Mapped Read/Write: 6 What is makeing the Stream Read/Write so unbelievably long? And as a read/write test, to me it looks a bit pointless to read the same integer over and over (if I understand well what's going on in the Stream Read/Write) Wouldn't it be better to read int's from the previously written file and just read and write ints on the same place? Is there a better way to illustrate it? I've been breaking my head about a lot of these things for a while and I just can't get the whole picture..

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  • Where can a self-teacher learn general good programming habits and conventions?

    - by lucid
    A few mistakes and general childishness in early adulthood have left me in a situation where I work a menial job, with no possibility (in the near future) of attending school. I aspire to one day work in the programming field (gaming specifically), after proving myself on the indie end of things. I've gotten very confident in C++, java, and python, and I find I'm able to solve any problem I want either from previous experience, or from scouring the web for help. The solutions work, and with each attempt they become more readable, maintainable, and extensible. But this is because I'm learning from mistakes and bad programming and design habits I feel I might have avoided with actual schooling. General tips like: "if it's hard to read or getting long, or you're writing it twice, it should be in one or more functions." or "design all your classes before you start coding, so you don't have to rewrite classes later when you discover an unforeseen dependency" Is there a good book or website for learning general good programming practices and design habits? Also, naming and format conventions. I realize sometimes development houses have their own conventions, but things like "Classes in python usually have the first letter of each word capitalized". I'd like to be able to show some source code to a potential employer, and be prepared when for what's expected on a team. Is there some central database of naming and formatting conventions somewhere? Also, feel free to give any thoughts on whether or not the self-teach, garner some indie sales, use them as your resume' route is realistic

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