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• JPA Entity Manager resource handling

  - by chiragshahkapadia

  Every time I call JPA method its creating entity and binding query. My persistence properties are: <property name="hibernate.dialect" value="org.hibernate.dialect.Oracle10gDialect"/> <property name="hibernate.cache.provider_class" value="net.sf.ehcache.hibernate.SingletonEhCacheProvider"/> <property name="hibernate.cache.use_second_level_cache" value="true"/> <property name="hibernate.cache.use_query_cache" value="true"/> And I am creating entity manager the way shown below: emf = Persistence.createEntityManagerFactory("pu"); em = emf.createEntityManager(); em = Persistence.createEntityManagerFactory("pu").createEntityManager(); Is there any nice way to manage entity manager resource instead create new every time or any property can set in persistence. Remember it's JPA. See below binding log every time : 15:35:15,527 INFO [AnnotationBinder] Binding entity from annotated class: * 15:35:15,527 INFO [QueryBinder] Binding Named query: * = * 15:35:15,527 INFO [QueryBinder] Binding Named query: * = * 15:35:15,527 INFO [QueryBinder] Binding Named query: 15:35:15,527 INFO [QueryBinder] Binding Named query: 15:35:15,527 INFO [QueryBinder] Binding Named query: 15:35:15,527 INFO [QueryBinder] Binding Named query: 15:35:15,527 INFO [QueryBinder] Binding Named query: 15:35:15,527 INFO [QueryBinder] Binding Named query: 15:35:15,527 INFO [QueryBinder] Binding Named query: 15:35:15,527 INFO [EntityBinder] Bind entity com.* on table * 15:35:15,542 INFO [HibernateSearchEventListenerRegister] Unable to find org.hibernate.search.event.FullTextIndexEventListener on the classpath. Hibernate Search is not enabled. 15:35:15,542 INFO [NamingHelper] JNDI InitialContext properties:{} 15:35:15,542 INFO [DatasourceConnectionProvider] Using datasource: 15:35:15,542 INFO [SettingsFactory] RDBMS: and Real Application Testing options 15:35:15,542 INFO [SettingsFactory] JDBC driver: Oracle JDBC driver, version: 9.2.0.1.0 15:35:15,542 INFO [Dialect] Using dialect: org.hibernate.dialect.Oracle10gDialect 15:35:15,542 INFO [TransactionFactoryFactory] Transaction strategy: org.hibernate.transaction.JDBCTransactionFactory 15:35:15,542 INFO [TransactionManagerLookupFactory] No TransactionManagerLookup configured (in JTA environment, use of read-write or transactional second-level cache is not recomm ended) 15:35:15,542 INFO [SettingsFactory] Automatic flush during beforeCompletion(): disabled 15:35:15,542 INFO [SettingsFactory] Automatic session close at end of transaction: disabled 15:35:15,542 INFO [SettingsFactory] JDBC batch size: 15 15:35:15,542 INFO [SettingsFactory] JDBC batch updates for versioned data: disabled 15:35:15,542 INFO [SettingsFactory] Scrollable result sets: enabled 15:35:15,542 INFO [SettingsFactory] JDBC3 getGeneratedKeys(): disabled 15:35:15,542 INFO [SettingsFactory] Connection release mode: auto 15:35:15,542 INFO [SettingsFactory] Default batch fetch size: 1 15:35:15,542 INFO [SettingsFactory] Generate SQL with comments: disabled 15:35:15,542 INFO [SettingsFactory] Order SQL updates by primary key: disabled 15:35:15,542 INFO [SettingsFactory] Order SQL inserts for batching: disabled 15:35:15,542 INFO [SettingsFactory] Query translator: org.hibernate.hql.ast.ASTQueryTranslatorFactory 15:35:15,542 INFO [ASTQueryTranslatorFactory] Using ASTQueryTranslatorFactory 15:35:15,542 INFO [SettingsFactory] Query language substitutions: {} 15:35:15,542 INFO [SettingsFactory] JPA-QL strict compliance: enabled 15:35:15,542 INFO [SettingsFactory] Second-level cache: enabled 15:35:15,542 INFO [SettingsFactory] Query cache: enabled 15:35:15,542 INFO [SettingsFactory] Cache region factory : org.hibernate.cache.impl.bridge.RegionFactoryCacheProviderBridge 15:35:15,542 INFO [RegionFactoryCacheProviderBridge] Cache provider: net.sf.ehcache.hibernate.SingletonEhCacheProvider 15:35:15,542 INFO [SettingsFactory] Optimize cache for minimal puts: disabled 15:35:15,542 INFO [SettingsFactory] Structured second-level cache entries: disabled 15:35:15,542 INFO [SettingsFactory] Query cache factory: org.hibernate.cache.StandardQueryCacheFactory 15:35:15,542 INFO [SettingsFactory] Statistics: disabled 15:35:15,542 INFO [SettingsFactory] Deleted entity synthetic identifier rollback: disabled 15:35:15,542 INFO [SettingsFactory] Default entity-mode: pojo 15:35:15,542 INFO [SettingsFactory] Named query checking : enabled 15:35:15,542 INFO [SessionFactoryImpl] building session factory 15:35:15,542 INFO [SessionFactoryObjectFactory] Not binding factory to JNDI, no JNDI name configured 15:35:15,542 INFO [UpdateTimestampsCache] starting update timestamps cache at region: org.hibernate.cache.UpdateTimestampsCache 15:35:15,542 INFO [StandardQueryCache] starting query cache at region: org.hibernate.cache.StandardQueryCache

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• When should I use indexed arrays of OpenGL vertices?

  - by Tartley

  I'm trying to get a clear idea of when I should be using indexed arrays of OpenGL vertices, drawn with gl[Multi]DrawElements and the like, versus when I should simply use contiguous arrays of vertices, drawn with gl[Multi]DrawArrays. (Update: The consensus in the replies I got is that one should always be using indexed vertices.) I have gone back and forth on this issue several times, so I'm going to outline my current understanding, in the hopes someone can either tell me I'm now finally more or less correct, or else point out where my remaining misunderstandings are. Specifically, I have three conclusions, in bold. Please correct them if they are wrong. One simple case is if my geometry consists of meshes to form curved surfaces. In this case, the vertices in the middle of the mesh will have identical attributes (position, normal, color, texture coord, etc) for every triangle which uses the vertex. This leads me to conclude that: 1. For geometry with few seams, indexed arrays are a big win. Follow rule 1 always, except: For geometry that is very 'blocky', in which every edge represents a seam, the benefit of indexed arrays is less obvious. To take a simple cube as an example, although each vertex is used in three different faces, we can't share vertices between them, because for a single vertex, the surface normals (and possible other things, like color and texture co-ord) will differ on each face. Hence we need to explicitly introduce redundant vertex positions into our array, so that the same position can be used several times with different normals, etc. This means that indexed arrays are of less use. e.g. When rendering a single face of a cube: 0 1 o---o |\ | | \ | | \| o---o 3 2 (this can be considered in isolation, because the seams between this face and all adjacent faces mean than none of these vertices can be shared between faces) if rendering using GL_TRIANGLE_FAN (or _STRIP), then each face of the cube can be rendered thus: verts = [v0, v1, v2, v3] colors = [c0, c0, c0, c0] normal = [n0, n0, n0, n0] Adding indices does not allow us to simplify this. From this I conclude that: 2. When rendering geometry which is all seams or mostly seams, when using GL_TRIANGLE_STRIP or _FAN, then I should never use indexed arrays, and should instead always use gl[Multi]DrawArrays. (Update: Replies indicate that this conclusion is wrong. Even though indices don't allow us to reduce the size of the arrays here, they should still be used because of other performance benefits, as discussed in the comments) The only exception to rule 2 is: When using GL_TRIANGLES (instead of strips or fans), then half of the vertices can still be re-used twice, with identical normals and colors, etc, because each cube face is rendered as two separate triangles. Again, for the same single cube face: 0 1 o---o |\ | | \ | | \| o---o 3 2 Without indices, using GL_TRIANGLES, the arrays would be something like: verts = [v0, v1, v2, v2, v3, v0] normals = [n0, n0, n0, n0, n0, n0] colors = [c0, c0, c0, c0, c0, c0] Since a vertex and a normal are often 3 floats each, and a color is often 3 bytes, that gives, for each cube face, about: verts = 6 * 3 floats = 18 floats normals = 6 * 3 floats = 18 floats colors = 6 * 3 bytes = 18 bytes = 36 floats and 18 bytes per cube face. (I understand the number of bytes might change if different types are used, the exact figures are just for illustration.) With indices, we can simplify this a little, giving: verts = [v0, v1, v2, v3] (4 * 3 = 12 floats) normals = [n0, n0, n0, n0] (4 * 3 = 12 floats) colors = [c0, c0, c0, c0] (4 * 3 = 12 bytes) indices = [0, 1, 2, 2, 3, 0] (6 shorts) = 24 floats + 12 bytes, and maybe 6 shorts, per cube face. See how in the latter case, vertices 0 and 2 are used twice, but only represented once in each of the verts, normals and colors arrays. This sounds like a small win for using indices, even in the extreme case of every single geometry edge being a seam. This leads me to conclude that: 3. When using GL_TRIANGLES, one should always use indexed arrays, even for geometry which is all seams. Please correct my conclusions in bold if they are wrong.

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• How do you control the playback levels (decibles?) using the iPhone AVAudioPlayer? Or do I need to u

  - by Joshua

  My audio clips sound perfect when I upload them to the iPhone via iTunes. And I am pretty sure it is because the iPod has a maximum playback level, so the audio doesn't sound overdriven. In my app, I include the same audio files, and when I play them [myAudio play]; the levels are so high that the audio becomes indiscernible. I found in the library http://developer.apple.com/iphone/library/documentation/AVFoundation/Reference/AVAudioPlayerClassReference/Reference/Reference.html#//apple_ref/doc/uid/TP40008067-CH1-SW2 that it says that you can "Control relative playback level for each sound you are playing" but I've been searching this issue out for hours and I haven't gotten anywhere. Any help would be wonderful!

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• Monorail - Form submission using GET instead of POST

  - by Septih

  Hello, I'm writing some additions to a Castle MonoRail based site involving an Add and an Edit form. The add form works fine and uses POST but the edit form uses GET. The only major difference I can see is that the edit method is called with the Id of the object being edited in the query string. When the submit button is pressed on the edit form, the only argument passed is this object Id again. Here is the code for the edit form: <form action="edit.ashx" method="post"> <h3>Coupon Description</h3> <textarea name="comments" width="200">$comments</textarea> <br/><br/> <h3>Coupon Actions</h3> <br/> <div>Give Stories</div> <ul class="checklist" style="overflow:auto;height:144px;width:100%"> #foreach ($story in $stories.Values) <li> <label> #set ($associated = "") #foreach($storyId in $storyIds) #if($story.Id == $storyId) #set($associated = " checked='true'") #end #end <input type="checkbox" name="chk_${story.Id}" id="chk_${story.Id}" value="true" class="checkbox" $associated/> $story.Name </label> </li> #end </ul> <br/><br/> <div>Give Credit Amount</div> <input type="text" name="credit" value="$credit" /> <br/><br/> <h3>Coupon Uses</h3> <input type="checkbox" name="multi" #if($multi) checked="true" #end /> Multi-Use Coupon?<br/><br/> <b>OR</b> <br/> <br/> Number of Uses per Coupon: <input type="text" name="uses" value="$uses" /> <br/> <input type="submit" name="Save" /> </form> The differences between this and the add form is the velocity stuff to do with association and the values of the inputs being from the PropertyBag. The Method dealing with this on the controller starts like this: public void Edit(int id) { Coupon coupon = Coupon.GetRepository(User.Site.Id).FindById(id).Value; if(coupon == null) { RedirectToReferrer(); return; } IFutureQueryOfList<Story> stories = Story.GetRepository(User.Site.Id).OnlyReturnEnabled().FindAll("Name", true); if (Params["Save"] == null) { ... } } It reliably gets called but a breakpoint on the Params["Save"] lets me see that the HttpMethod is "GET" and the only arguments passed (In the Form and the Request) are the object Id and additional HTTP headers. At the end of the day I'm not that familiar with MonoRail and this may be a stupid mistake on my behalf, but I would very much appreciate being made a fool out of if it fixes the problem! :) Thanks

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• How would I go about building a calendar UI control for the iPhone/iPad?

  - by BeachRunnerJoe

  Hello. There are a few different 3rd party code frameworks that include calendar controls, but most of them have a lot of functionality I don't need, plus most of them lack sufficient documentation on how to use them and I'm not a proficient enough iPhone developer figure it out using just the code. So I'm going to attempt to build my own and I was hoping you could provide me with some high-level direction to get started. At a high level, how could I build a simple, calendar control that doesn't do much more than display a calendar (month view, with the current date highlighted) and allows the user to selected a date? Something that looks like the calendar in the upper right corner of this image... Thanks so much in advance for your help!

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• Markers in Google Maps Application

  - by Samuh

  I am supposed to display a certain location using Google Maps application. I have lat/long values and tried Intent.ACTION_VIEW with "geo:lat,long?z=15" uri. The Google Maps application loads centered on the supplied lat-long value but obviously does not display any marker(overlays) pin-pointing the location. Is it possible to request the Google Maps App to display markers? Also, the zoom level paramater doesnt seem to work. Maps load at the default zoom level of 10. I can easily achieve this using MapActivity but Google Map App is what is desired. Thanks

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• Mixed Table Type with other types as parameters to Stored Procedured c#

  - by amemak

  Hi, I am asking about how could i pass multi parameters to a stored procedure, one of these parameters is user defined table. When I tried to do it it shows this error: INSERT INTO BD (ID, VALUE, BID) values( (SELECT t1.ID, t1.Value FROM @Table AS t1),someintvalue) here @Table is the user defined table parameter. Msg 116, Level 16, State 1, Procedure UpdateBD, Line 12 Only one expression can be specified in the select list when the subquery is not introduced with EXISTS. Msg 109, Level 15, State 1, Procedure UpdateBD, Line 11 There are more columns in the INSERT statement than values specified in the VALUES clause. The number of values in the VALUES clause must match the number of columns specified in the INSERT statement. Thank you

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• VS2010's "Public Property <PropertyName> As <DataType> vs. Public var

  - by Velika2

  In VS2008, I used to type Public Property <PropName> As <dataType> and hit the Enter key and the IDE editor would automatically expand it out to a full blown property block. Now, from what I understand, a new feature of 2010 is that the compiler automatically "expands" the short syntax above into the same IL code that you would get with the full property GET AND SET sub methods that were are accustomed to seeing before in the editor. But functionality, how the heck is this any different than just having a Public class level variable? If the only diff is what it compiles to and if otehrwise there is no functional difference, isn't the new way less efficient than the old since it involves more code than just having a class level memory variable? Public as I thought that if you weren't going to have code behind your properties that they were essentially the same. I guess the diffrenece is that they just added the keyword "Property" but functionality, their is no diff, eh?

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• Watin File Download Problem

  - by EmrahIlker

  When I clicked button with mouse, File Download Dialog opens directly. But when Watin Button Click methods click the vert same button on same ie window this message appears and wait my confirm To help protect your security, Internet Explorer blocked this site from downloading files to your computer. Click here for options. I turned off the Information bar for file downloads,(Internet Options-Security-Custom Level-Downloads-Automatic prompting for file downloads--Enable),allow active x content, lower security level for internet etc.. but didn't work. I'm using Win 7, IE8.

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• Trying to configure HWIC-3G-HSPA

  - by user1174838

  I'm trying to configure a couple of Cisco 1941 routes. The are both identical routers. Each as a HWIC-1T (Smart Serial interface) and a HWIC-3G-HSPA 3G interface. These routers are to be sent to remote sites. We have connectivity to one of the sites but if remote site A gors down we lose connectivity to remote site B. The HWIC-1T is the primary WAN interface using frame relay joining the two remote sites We want the HWIC-3G-HSPA to be usable for direct connectivity from head office to remote site B, and also the HWIC-3G-HSPA is do be used for comms between the remote sites when the frame relay is down (happens quite a bit). I initialy tried to do dynamic routing using EIGRP however in my lab setup of laptop - 1941 - 1941 - laptop, I was unable to get end to end connectivity. I later settled on static routing and have got end to end connectivity but only over frame relay, not the HWIC-3G-HSPA. The sanitized running config for remote site A: version 15.1 service tcp-keepalives-in service tcp-keepalives-out service timestamps debug datetime msec service timestamps log datetime msec service password-encryption service udp-small-servers service tcp-small-servers ! hostname remoteA ! boot-start-marker boot-end-marker ! ! logging buffered 51200 warnings enable secret 5 censored ! no aaa new-model clock timezone wst 8 0 ! no ipv6 cef ip source-route ip cef ! ip domain name yourdomain.com multilink bundle-name authenticated ! chat-script gsm "" "ATDT*98*1#" TIMEOUT 30 "CONNECT" ! username admin privilege 15 secret 5 censored ! controller Cellular 0/1 ! interface Embedded-Service-Engine0/0 no ip address shutdown ! interface GigabitEthernet0/0 ip address 192.168.2.5 255.255.255.0 duplex auto speed auto ! interface GigabitEthernet0/1 no ip address shutdown duplex auto speed auto ! interface Serial0/0/0 ip address 10.1.1.2 255.255.255.252 encapsulation frame-relay cdp enable frame-relay interface-dlci 16 frame-relay lmi-type ansi ! interface Cellular0/1/0 ip address negotiated encapsulation ppp dialer in-band dialer idle-timeout 2147483 dialer string gsm dialer-group 1 async mode interactive ppp chap hostname censored ppp chap password 7 censored cdp enable ! interface Cellular0/1/1 no ip address encapsulation ppp ! interface Dialer0 no ip address ! ip forward-protocol nd ! no ip http server no ip http secure-server ! ip route 0.0.0.0 0.0.0.0 Serial0/0/0 210 permanent ip route 0.0.0.0 0.0.0.0 Cellular0/1/0 220 permanent ip route 172.31.2.0 255.255.255.0 Cellular0/1/0 permanent ip route 192.168.3.0 255.255.255.0 10.1.1.1 permanent ip route 192.168.3.0 255.255.255.0 Cellular0/1/0 210 permanent ! access-list 1 permit any dialer-list 1 protocol ip list 1 ! control-plane ! line con 0 logging synchronous login local line aux 0 line 2 no activation-character no exec transport preferred none transport input all transport output pad telnet rlogin lapb-ta mop udptn v120 ssh stopbits 1 line 0/1/0 exec-timeout 0 0 script dialer gsm login modem InOut no exec transport input all rxspeed 7200000 txspeed 5760000 line 0/1/1 no exec rxspeed 7200000 txspeed 5760000 line vty 0 4 access-class 23 in privilege level 15 password 7 censored login local transport input all line vty 5 15 access-class 23 in privilege level 15 password 7 censored login local transport input all line vty 16 1370 password 7 censored login transport input all ! scheduler allocate 20000 1000 end The sanitized running config for remote site B: version 15.1 service tcp-keepalives-in service tcp-keepalives-out service timestamps debug datetime msec service timestamps log datetime msec service password-encryption service udp-small-servers service tcp-small-servers ! hostname remoteB ! boot-start-marker boot-end-marker ! logging buffered 51200 warnings enable secret 5 censored ! no aaa new-model clock timezone wst 8 0 ! no ipv6 cef ip source-route ip cef ! no ip domain lookup ip domain name yourdomain.com multilink bundle-name authenticated ! chat-script gsm "" "ATDT*98*1#" TIMEOUT 30 "CONNECT" username admin privilege 15 secret 5 censored ! controller Cellular 0/1 ! interface Embedded-Service-Engine0/0 no ip address shutdown ! interface GigabitEthernet0/0 ip address 192.168.3.1 255.255.255.0 duplex auto speed auto ! interface GigabitEthernet0/1 no ip address shutdown duplex auto speed auto ! interface Serial0/0/0 ip address 10.1.1.1 255.255.255.252 encapsulation frame-relay clock rate 2000000 cdp enable frame-relay interface-dlci 16 frame-relay lmi-type ansi frame-relay intf-type dce ! interface Cellular0/1/0 ip address negotiated encapsulation ppp dialer in-band dialer idle-timeout 2147483 dialer string gsm dialer-group 1 async mode interactive ppp chap hostname censored ppp chap password 7 censored ppp ipcp dns request cdp enable ! interface Cellular0/1/1 no ip address encapsulation ppp ! interface Dialer0 no ip address ! ip forward-protocol nd ! no ip http server no ip http secure-server ! ip route 0.0.0.0 0.0.0.0 Serial0/0/0 210 permanent ip route 0.0.0.0 0.0.0.0 Cellular0/1/0 220 permanent ip route 172.31.2.0 255.255.255.0 Cellular0/1/0 permanent ip route 192.168.2.0 255.255.255.0 10.1.1.2 permanent ip route 192.168.2.0 255.255.255.0 Cellular0/1/0 210 permanent ! kron occurrence PING in 1 recurring policy-list ICMP ! access-list 1 permit any dialer-list 1 protocol ip list 1 ! control-plane ! line con 0 logging synchronous login local line aux 0 line 2 no activation-character no exec transport preferred none transport input all transport output pad telnet rlogin lapb-ta mop udptn v120 ssh stopbits 1 line 0/1/0 exec-timeout 0 0 script dialer gsm login modem InOut no exec transport input all rxspeed 7200000 txspeed 5760000 line 0/1/1 no exec rxspeed 7200000 txspeed 5760000 line vty 0 4 access-class 23 in privilege level 15 password 7 censored login transport input all line vty 5 15 access-class 23 in privilege level 15 password 7 censored login transport input all line vty 16 1370 password 7 censored login transport input all ! scheduler allocate 20000 1000 end The last problem I'm having is the 3G interfaces go down after only a few minutes of inactivity. I've tried using kron to ping the local HWIC-3G-HSPA interface (cellular 0/1/0) every minute but that hasn't been successful. Manually pinging the IP assigned (by the telco) to ce0/1/0 does bring the interface up. Any ideas? Thanks

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• feature extraction from acoustic signals

  - by Dolphin

  Hi everyone, It's been a while. I found APIs in Java for extracting features from acoustic audio files and symbolic files separately. But now I have a problem in mapping from low level wav audio features to high level midi features. i.e. I need to write the extracted wav audio features on to midi format. But I cannot think of anything even close to it. Can someone pls provide me some insight as in how I can approach this. Greatly appreciate your responses. Advance thanks

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• Does mod_rewrite in subdirectories' .htaccess override higher levels?

  - by Ryan

  I'm using mod_rewrite to map my old directory structure to a new one. I have the following rule in my top-level .htaccess file, and it works: RewriteEngine On RewriteCond %{REQUEST_URI} /blog/archives/(.*) RewriteRule ^.*$ /archives/%1 [L,R=301] As you can guess, this takes http://example.com/blog/archives/00001.php and redirects it to http://example.com/archives/00001.php. But when I add these rewrite rules to the .htaccess file in the /blog directory RewriteEngine on RewriteRule atom.xml$ /atom.xml [L,R=301] the top-level redirect no longer works. If I move the rule in the /blog .htaccess file to the top-levle file both rules work. Can someone explain what is happening here?

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• Why isn't Hadoop implemented using MPI?

  - by artif

  Correct me if I'm wrong, but my understanding is that Hadoop does not use MPI for communication between different nodes. What are the technical reasons for this? I could hazard a few guesses, but I do not know enough of how MPI is implemented "under the hood" to know whether or not I'm right. Come to think of it, I'm not entirely familiar with Hadoop's internals either. I understand the framework at a conceptual level (map/combine/shuffle/reduce and how that works at a high level) but I don't know the nitty gritty implementation details. I've always assumed Hadoop was transmitting serialized data structures (perhaps GPBs) over a TCP connection, eg during the shuffle phase. Let me know if that's not true.

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• Are frameworks using byte-code generation creating leaky abstractions?

  - by Gabriel Šcerbák

  My point is, if you don't understand the abstraction of a framework, you can still decompile it and understand it, because you know the language e.g. Java. However, when byte-code generation happens, you have to understand even a lower level - JVM level byte-codes. I am really affraid of using any of such frameworks, which are many. Most of the time I think the reason for byte-code generation is simply lack of language features such as metaprogramming. Do you agree? What is your opinion and argument? How do you take over the problem with leaky abstractions in those frameworks?

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• Languages and VMs: Features that are hard to optimize and why

  - by mrjoltcola

  I'm doing a survey of features in preparation for a research project. Name a mainstream language or language feature that is hard to optimize, and why the feature is or isn't worth the price paid, or instead, just debunk my theories below with anecdotal evidence. Before anyone flags this as subjective, I am asking for specific examples of languages or features, and ideas for optimization of these features, or important features that I haven't considered. Also, any references to implementations that prove my theories right or wrong. Top on my list of hard to optimize features and my theories (some of my theories are untested and are based on thought experiments): 1) Runtime method overloading (aka multi-method dispatch or signature based dispatch). Is it hard to optimize when combined with features that allow runtime recompilation or method addition. Or is it just hard, anyway? Call site caching is a common optimization for many runtime systems, but multi-methods add additional complexity as well as making it less practical to inline methods. 2) Type morphing / variants (aka value based typing as opposed to variable based) Traditional optimizations simply cannot be applied when you don't know if the type of someting can change in a basic block. Combined with multi-methods, inlining must be done carefully if at all, and probably only for a given threshold of size of the callee. ie. it is easy to consider inlining simple property fetches (getters / setters) but inlining complex methods may result in code bloat. The other issue is I cannot just assign a variant to a register and JIT it to the native instructions because I have to carry around the type info, or every variable needs 2 registers instead of 1. On IA-32 this is inconvenient, even if improved with x64's extra registers. This is probably my favorite feature of dynamic languages, as it simplifies so many things from the programmer's perspective. 3) First class continuations - There are multiple ways to implement them, and I have done so in both of the most common approaches, one being stack copying and the other as implementing the runtime to use continuation passing style, cactus stacks, copy-on-write stack frames, and garbage collection. First class continuations have resource management issues, ie. we must save everything, in case the continuation is resumed, and I'm not aware if any languages support leaving a continuation with "intent" (ie. "I am not coming back here, so you may discard this copy of the world"). Having programmed in the threading model and the contination model, I know both can accomplish the same thing, but continuations' elegance imposes considerable complexity on the runtime and also may affect cache efficienty (locality of stack changes more with use of continuations and co-routines). The other issue is they just don't map to hardware. Optimizing continuations is optimizing for the less-common case, and as we know, the common case should be fast, and the less-common cases should be correct. 4) Pointer arithmetic and ability to mask pointers (storing in integers, etc.) Had to throw this in, but I could actually live without this quite easily. My feelings are that many of the high-level features, particularly in dynamic languages just don't map to hardware. Microprocessor implementations have billions of dollars of research behind the optimizations on the chip, yet the choice of language feature(s) may marginalize many of these features (features like caching, aliasing top of stack to register, instruction parallelism, return address buffers, loop buffers and branch prediction). Macro-applications of micro-features don't necessarily pan out like some developers like to think, and implementing many languages in a VM ends up mapping native ops into function calls (ie. the more dynamic a language is the more we must lookup/cache at runtime, nothing can be assumed, so our instruction mix is made up of a higher percentage of non-local branching than traditional, statically compiled code) and the only thing we can really JIT well is expression evaluation of non-dynamic types and operations on constant or immediate types. It is my gut feeling that bytecode virtual machines and JIT cores are perhaps not always justified for certain languages because of this. I welcome your answers.

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• postgresql syntax while exists loop

  - by veilig

  I'm working at function from Joe Celkos book - Trees and Hierarchies in SQL for Smarties I'm trying to delete a subtree from an adjacency list but part my function is not working yet. WHILE EXISTS –– mark leaf nodes (SELECT * FROM OrgChart WHERE boss_emp_nbr = -99999 AND emp_nbr > -99999) LOOP –– get list of next level subordinates DELETE FROM WorkingTable; INSERT INTO WorkingTable SELECT emp_nbr FROM OrgChart WHERE boss_emp_nbr = -99999; –– mark next level of subordinates UPDATE OrgChart SET emp_nbr = -99999 WHERE boss_emp_nbr IN (SELECT emp_nbr FROM WorkingTable); END LOOP; my question: is the WHILE EXISTS correct for use w/ postgresql? I appear to be stumbling and getting caught in an infinite loop in this part. Perhaps there is a more correct syntax I am unaware of.

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• Javascript Input type

  - by Phoenix

  Hi All, In javascript we use input type = file .. to open up a file browser pop-up .. is there a way to limit access to folders .. I want to select a folder then ftp all the files in the folder .. so i need access upto only the folder level and not file level .. i guess it would be tedious to go an manually select every file from the folder and then ftp .. is there a way to do that.. Also, how can i set the file-browser pop-up window path to a default one ?

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• How do I prevent my form from freezing when it is loading an image from the web at the click of a button?

  - by Vimal Basdeo

  I want to display an image from the web to a panel in another Jframe at the click of a button but whenever I click the button first the image loads and during this time the current form potentially freezes and once the image has loaded the form is displayed with the image.. How can I avoid the situation where my form freezes since it is very irritating My codes :: My current class private void btn_TrackbusActionPerformed(java.awt.event.ActionEvent evt) { try { sendMessage("Query,map,$,start,211,Arsenal,!"); System.out.println(receiveMessage()); } catch (UnknownHostException ex) { Logger.getLogger(client_Trackbus.class.getName()).log(Level.SEVERE, null, ex); } catch (IOException ex) { Logger.getLogger(client_Trackbus.class.getName()).log(Level.SEVERE, null, ex); } catch (Exception ex) { Logger.getLogger(client_Trackbus.class.getName()).log(Level.SEVERE, null, ex); } client_trackedbus nextform=new client_trackedbus(planform,connection,packet_receive,packet_send); this.setVisible(false); this.dispose(); nextform.setVisible(true); // TODO add your handling code here: } My next class that displays the image public class client_trackedbus extends javax.swing.JFrame { client_planform planform=null; DatagramSocket connection=null; DatagramPacket packet_receive=null; DatagramPacket packet_send=null; JLabel label=null; /** Creates new form client_trackedbus */ public client_trackedbus(client_planform planform,DatagramSocket connection,DatagramPacket packet_receive,DatagramPacket packet_send) { initComponents(); this.planform=planform; this.connection=connection; this.packet_receive=packet_receive; this.packet_send=packet_send; try { displayMap("http://www.huddletogether.com/projects/lightbox2/images/image-2.jpg", jPanel1, new JLabel()); } catch (MalformedURLException ex) { Logger.getLogger(client_trackedbus.class.getName()).log(Level.SEVERE, null, ex); } } private void displayMap(String url,JPanel panel,JLabel label) throws MalformedURLException{ URL imageurl=new URL(url); Image image=(Toolkit.getDefaultToolkit().createImage(imageurl)); ImageIcon icon = new ImageIcon(image); label.setIcon(icon); panel.add(label); // System.out.println(panel.getSize().width); this.getContentPane().add(panel); } /** This method is called from within the constructor to * initialize the form. * WARNING: Do NOT modify this code. The content of this method is * always regenerated by the Form Editor. */ @SuppressWarnings("unchecked") // <editor-fold defaultstate="collapsed" desc="Generated Code"> private void initComponents() { jPanel1 = new javax.swing.JPanel(); jLabel1 = new javax.swing.JLabel(); btn_Exit = new javax.swing.JButton(); btn_Plan = new javax.swing.JButton(); setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE); setTitle("Public Transport Journey Planner"); javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1); jPanel1.setLayout(jPanel1Layout); jPanel1Layout.setHorizontalGroup( jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGap(0, 368, Short.MAX_VALUE) ); jPanel1Layout.setVerticalGroup( jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGap(0, 172, Short.MAX_VALUE) ); jLabel1.setFont(new java.awt.Font("Arial", 1, 18)); jLabel1.setText("Your tracked bus"); btn_Exit.setText("Exit"); btn_Exit.addActionListener(new java.awt.event.ActionListener() { public void actionPerformed(java.awt.event.ActionEvent evt) { btn_ExitActionPerformed(evt); } }); btn_Plan.setText("Plan journey"); btn_Plan.addActionListener(new java.awt.event.ActionListener() { public void actionPerformed(java.awt.event.ActionEvent evt) { btn_PlanActionPerformed(evt); } }); javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane()); getContentPane().setLayout(layout); layout.setHorizontalGroup( layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGroup(layout.createSequentialGroup() .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGroup(layout.createSequentialGroup() .addGap(104, 104, 104) .addComponent(jLabel1)) .addGroup(layout.createSequentialGroup() .addContainerGap() .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)) .addGroup(layout.createSequentialGroup() .addGap(65, 65, 65) .addComponent(btn_Plan) .addGap(65, 65, 65) .addComponent(btn_Exit, javax.swing.GroupLayout.PREFERRED_SIZE, 87, javax.swing.GroupLayout.PREFERRED_SIZE))) .addContainerGap(20, Short.MAX_VALUE)) ); layout.setVerticalGroup( layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGroup(layout.createSequentialGroup() .addGap(35, 35, 35) .addComponent(jLabel1) .addGap(18, 18, 18) .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE) .addGap(18, 18, 18) .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE) .addComponent(btn_Exit) .addComponent(btn_Plan)) .addContainerGap(12, Short.MAX_VALUE)) ); pack(); }// </editor-fold> private void btn_ExitActionPerformed(java.awt.event.ActionEvent evt) { // TODO add your handling code here: Exitform(); } private void btn_PlanActionPerformed(java.awt.event.ActionEvent evt) { // TODO add your handling code here: this.setVisible(false); this.dispose(); this.planform.setVisible(true); } private void Exitform(){ this.setVisible(false); this.dispose(); } /** * @param args the command line arguments */ public static void main(String args[]) { java.awt.EventQueue.invokeLater(new Runnable() { public void run() { // new client_trackedbus().setVisible(true); } }); } // Variables declaration - do not modify private javax.swing.JButton btn_Exit; private javax.swing.JButton btn_Plan; private javax.swing.JLabel jLabel1; private javax.swing.JPanel jPanel1; // End of variables declaration }

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• deep injection - spring

  - by Bob

  What is the best way (or options) for accessing spring components at layers deep within the application that aren't managed by spring? For example, I have a low level utility POJO class into which I need to autowire/inject a spring component. I'll call it LowLevelHelper. There are multiple classes that use LowLevelHelper - most are layers away from anything that is hooked up with spring. One option would be to make all the layers in to spring components, but that seems like I'm hacking my design to force spring to help me. I have some complex things going on that won't be nearly as clean if I have to @Autowire all the pieces and don't new anything. Another option might be to manually inject the component in the low level class, but I'm not really sure if this is possible or the right solution.

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• Where to open sessions in a Spring/Hibernate stack?

  - by CaptainAwesomePants

  I'm trying to figure out a good design for a Spring/Hibernate app. When creating such an app, it appears like there are a handful of major decisions. The first major decision seems to be where to put the session/transaction boundary. It seems like I have 3 major choices: as a filter before controllers are even invoked, immediately below the controllers at the service call level, and stuffed way below the business level in repository calls. It seems to me like the right call is the middle path, but I'm not sure. I don't want my transactions open too long, but at the same time, I don't want to constantly worry about detached objects and lazy loading in the business logic. Still, there are some downsides. For instance, it makes it hard for the business logic to make a remote call without holding up a transaction for a few seconds. I wonder if there's a better way?

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• Why won't this SQL CAST work?

  - by Kev

  I have a nvarchar(50) column in a SQL Server 2000 table defined as follows: TaskID nvarchar(50) NULL I need to fill this column with some random SQL Unique Identifiers (I am unable to change the column type to uniqueidentifier). I tried this: UPDATE TaskData SET TaskID = CAST(NEWID() AS nvarchar) but I got the following error: Msg 8115, Level 16, State 2, Line 1 Arithmetic overflow error converting expression to data type nvarchar. I also tried: UPDATE TaskData SET TaskID = CAST(NEWID() AS nvarchar(50)) but then got this error: Msg 8152, Level 16, State 6, Line 1 String or binary data would be truncated. I don't understand why this doesn't work but this does: DECLARE @TaskID nvarchar(50) SET @TaskID = CAST(NEW() AS nvarchar(50)) I also tried CONVERT(nvarchar, NEWID()) and CONVERT(nvarchar(50), NEWID()) but got the same errors.

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• Best approach to show big amount of "grid" data

  - by Jorge Ramírez

  Hello all. I am building an application for Android (1.5) that, after quering a webservice, shows to the user a big amount of data that should be displayed in a "grid" or "table" style. I must show a result of about 7 columns and 50 rows (for example a customer list with names, adresses, telephone number, sales amount last year and so). Obviously, the 7 columns will not fix in the screen and I would like the user would be able to scroll up/down and LEFT/RIGHT (important because of the number of columns) to explore the grid results. cell selection level is NOT necessary, as much I would need row selection level. What is the best approach to get this interface element? Listview / GridView / TableLayout? Thanks

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• How can I make this client as a multithread client?

  - by Johanna

  Hi, I have read a lot about multithread client but for this one,I can not make it multithread! would you please help me? public class MainClient implements Runnable{ private static InformationClass info = new InformationClass(); private static Socket c; private static String text; public static String getText() { return text; } public static void setText(String text) { MainClient.text = text; } private static PrintWriter os; private static BufferedReader is; static boolean closed = false; /** * @param args the command line arguments */ public static void main(String[] args) { MainFrame farme = new MainFrame(); farme.setVisible(true); try { c = new Socket("localhost", 5050); os = new PrintWriter(c.getOutputStream(), true); is = new BufferedReader(new InputStreamReader(c.getInputStream())); } catch (UnknownHostException ex) { Logger.getLogger(MainClient.class.getName()).log(Level.SEVERE, null, ex); } catch (IOException ex) { Logger.getLogger(MainClient.class.getName()).log(Level.SEVERE, null, ex); } } public static void active() { String teXt = MainClient.getText(); System.out.println(teXt); os.println(teXt); try { String line = is.readLine(); System.out.println("Text received: " + line); os.flush(); is.close(); is.close(); c.close(); } catch (IOException ex) { Logger.getLogger(MainClient.class.getName()).log(Level.SEVERE, null, ex); } } } also active method will be called when the client write something on the text area and then clicks on the send button. 2) also i have a question that: in the other class I have this action performed for my send button,does it mean that client is multithread?? private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) { new Thread(new Runnable() { @Override public void run() { // This gets run in a background thread String text = jTextArea1.getText(); jTextArea2.append(client.getCurrentName() + " : " + text + "\n"); MainClient.setText(client.getCurrentName() + " : " + text + "\n"); clear(); MainClient.active(); } }).start(); } Last EDIT: this is my active method: public static void active() { String teXt = MainClient.getText(); os.println(teXt); String line = is.readLine(); System.out.println("Text received: " + line); os.flush(); is.close(); is.close(); c.close(); }

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• Mimic property/list changes on an object on another object

  - by soundslike

  I need to mimic changes (property/list) changes on an object and then apply it to another object to keep the structure/property the same. In essence it's like cloning etc. the biz rules require certain properties to not be applied to the other object, so I can't just clone the object otherwise this would be easy. I've already walked the source object to get INotifyPropertyChanged and IListChanged events, so I have the "source" and the args (Property or List) changed event notifications. Given that I guess I could build a reflection "hierarchy path" starting from the top level of the source object to get to the Property or List changed "source" (which could be several levels deep). Ignoring for the moment that certain object properties should not propagate to the other object, what's a way to build this "path"? Is a brute force top level down to build the "path" (and discard on the way back up if we don't hit the original changed event "source") the only way to do it? Any clever ideas on how to mimic changes from one object to another object?

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• Accessing functions in a parent controller

  - by meridimus

  I have made a ViewController in XCode for an iPhone project I'm working on, but I have a question about nested ViewControllers and what the best way to access a parents ViewController functions? Essentially, at the moment I have a SwitchViewController with MenuViewController (nested) and GameViewController (nested, which renders OpenGL ES). At the moment, I have animated view switching controlled in the SwitchViewController which works. But I want to call it after a player has selected the level from the MenuViewController and run the appropriate level in GameViewController. Not rocket science, I know. What's the best way to call parent functions?

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