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• Why does Ruby have Rails while Python has no central framework?

  - by yar

  This is a(n) historical question, not a comparison-between-languages question: This article from 2005 talks about the lack of a single, central framework for Python. For Ruby, this framework is clearly Rails. Why, historically speaking, did this happen for Ruby but not for Python? (or did it happen, and that framework is Django?) Also, the hypothetical questions: would Python be more popular if it had one, good framework? Would Ruby be less popular if it had no central framework? [Please avoid discussions of whether Ruby or Python is better, which is just too open-ended to answer.] Edit: Though I thought this is obvious, I'm not saying that other frameworks do not exist for Ruby, but rather that the big one in terms of popularity is Rails. Also, I should mention that I'm not saying that frameworks for Python are not as good (or better than) Rails. Every framework has its pros and cons, but Rails seems to, as Ben Blank says in the one of the comments below, have surpassed Ruby in terms of popularity. There are no examples of that on the Python side. WHY? That's the question.

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• Stop Visual Studio from appending numbers to the end of new controls

  - by techturtle

  I am wondering if there is any way to stop Visual Studio 2010 from appending a number to the end of the ID on new controls I create. For example, when I add a new TextBox, I would prefer that it do this: <asp:TextBox ID="TextBox" runat="server"> <asp:TextBox ID="TextBox" runat="server"> <asp:TextBox ID="TextBox" runat="server"> Instead of this: <asp:TextBox ID="TextBox1" runat="server"> <asp:TextBox ID="TextBox2" runat="server"> <asp:TextBox ID="TextBox3" runat="server"> It would make it easier to rename them appropriately, so I don't have to arrow/mouse over and delete the number each time. As I was writing this, the "Questions that may already have your answer" suggested this: How do I prevent Visual Studio from renaming my controls? which admittedly was the biggest part of my annoyance, but that appears to turn off putting in an ID="" field altogether, not just for pasted controls. It would still be helpful to turn off the numbering for new, non-pasted controls and have it not rename pasted ones as well. At the moment I'm working with ASP.NET, but it would be nice if it there was a way to do it for WinForms as well. Before anyone suggests it, I do know that allowing it to append the numbers prevents name conflicts should I not rename them appropriately. However, I would much rather have it fail to compile so I know to fix the issue now (if I forget to name something properly) rather than find random "TextBox1" items lying around in the code later on.

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• C++ polymorphism, function calls

  - by moai

  Okay, I'm pretty inexperienced as a programmer, let alone in C++, so bear with me here. What I wanted to do was to have a container class hold a parent class pointer and then use polymorphism to store a child class object. The thing is that I want to call one of the child class's functions through the parent class pointer. Here's a sort of example of what I mean in code: class SuperClass { public: int x; } class SubClass : public SuperClass { public: void function1() { x += 1; } } class Container { public: SuperClass * alpha; Container(SuperClass& beta) { alpha = beta; } } int main() { Container cont = new Container(new SubClass); } (I'm not sure that's right, I'm still really shaky on pointers. I hope it gets the point across, at least.) So, I'm not entirely sure whether I can do this or not. I have a sneaking suspicion the answer is no, but I want to be sure. If someone has another way to accomplish this sort of thing, I'd be glad to hear it.

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• Using Maven for maintaining product documentation

  - by Waldheinz

  We are using Maven for building a Java server-style application. It consists of several modules (in a single Maven "reactor") which can be plugged together to generate a final product (essentially a .jar) with the features enabled that the customer needs. All the internals are documented using JavaDoc and all, but that's not what you can give to the customer to find out how to get the thing running. Currently we have an OpenOffice document which serves as end-user documentation. I'd like to integrate this documentation into the Maven build process where each module's documentation is maintained (hand-edited) together with the Module's sources and the final document can reference the required Module documentation sections, add some friendly foreword and, if possible at all, can reference into the JavaDocs. Ultimately, the document should be output as a PDF. Is there any experience on Maven plugins can help with this? Is DocBook the right tool? Maybe Latex? Or something completely different? A sound "stick with OpenOffice and some text blocks" could be an answer, too.

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• MySql Check if NOW() falls within a weekday/time range

  - by Niall

  I have a table as follows: CREATE TABLE `zonetimes` ( `id` int(11) unsigned NOT NULL AUTO_INCREMENT, `zone_id` int(10) unsigned NOT NULL, `active_from_day` tinyint(1) unsigned NOT NULL DEFAULT '2', `active_to_day` tinyint(1) unsigned NOT NULL DEFAULT '2', `active_from` time NOT NULL, `active_to` time NOT NULL PRIMARY KEY (`id`) ) ENGINE=MyISAM ; So, a user could add a time entry starting on a particular day and time and ending on a particular day and time, eg: Between Monday 08:00 and Friday 18:00 or Between Thursday 15:00 and Tuesday 15:00 (Note the crossover at the end of the week). I need to query this data and determine if a zone is currently active (NOW(), DAYOFWEEK() etc)... This is turning out to be quite tricky. If I didn't have overlaps, eg: from 'Wednesday 8pm to Tuesday 4am' or from 'Thursday 4pm to Tuesday 4pm' this would be easy with BETWEEN. Also, need to allow a user to add for the entire week, eg: Monday 8am - Monday 8am (This should be easy enough, eg: where (active_from_day=active_to_day AND active_from=active_to) OR .. Any ideas? Note: I found a similar question here Timespan - Check for weekday and time of day in mysql but it didn't get an answer. One of the suggestions was to store each day as a separate row. I would much rather store one time span for multiple days though.

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• Can anyone get app-engine plugin working with Grails on mac os x?

  - by tim

  I have been trying for 4 days to get app-engine and grails working together on my mac to no avail. I am using latest groovy/grails and appengine sdk versions. Im following the app-engine plugin step by step on the grails site.. http://grails.org/plugin/app-engine Groovy Version: 1.7.1 JVM: 1.5.0_22 Grails 1.3.0.RC1 echo $APPENGINE_HOME reveals /Users/markstim/appengine-java-sdk-1.3.2 I perform the following steps 1. grails create-app myapp 2. cd myapp; grails list-plugins reveals hibernate 1.3.0.RC1 -- Hibernate for Grails tomcat 1.3.0.RC1 -- Apache Tomcat plugin for Grails add the following line to Config.groovy google.appengine.application="myapp" install the plugin for app-engine grails install-plugin app-engine and answer 'jpa' when asked (no errors yet) installed plugins list now looks like app-engine 0.8.9 -- Grails AppEngine plugin gorm-jpa 0.7.1 -- GORM-JPA Plugin then grails run-app and get this error as the server is coming up... [java] WARNING: Nested in org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'pluginManager' defined in ServletContext resource [/WEB-INF/applicationContext.xml]: Invocation of init method failed; nested exception is org.codehaus.groovy.grails.exceptions.NewInstanceCreationException: Could not create a new instance of class [GormJpaGrailsPlugin]!: [java] java.lang.NoClassDefFoundError: org.grails.jpa.JpaPluginSupport then if i navigate to localhost:8080 I get HTTP ERROR: 503 Problem accessing /myapp. Reason: SERVICE_UNAVAILABLE Powered by Jetty://

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• Database cache that I'm not aware of?

  - by Martin

  I'm using asp.net mvc, linq2sql, iis7 and sqlserver express 2008. I get these intermittent server errors, primary key conflicts on insertion. I'm using a different setup on my development computer so I can't debug. After a while they go away. Restarting iis helps. I'm getting the feeling there is cache somewhere that I'm not aware of. Can somebody help me sort out these errors? Cannot insert duplicate key row in object 'dbo.EnquiryType' with unique index 'IX_EnquiryType'. Edits regarding Venemos answer Is it possible that another application is also accessing the same database simultaneously? Yes there is, but not this particular table and no inserts or updates. There is one other table with which I experience the same problem but it has to do with a different part of the model. How often an in what context do you create a new DataContext instance? Only once, using the singleton pattern. Are the primary keys generated by the database or by the application? Database. Which version of ASP.NET MVC and which version of .NET are you using? RC2 and 3.5.

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• Using std::ifstream to load in an array of struct data type into a std::vector

  - by Sent1nel

  I am working on a bitmap loader in C++ and when moving from the C style array to the std::vector I have run into an usual problem of which Google does not seem to have the answer. 8 Bit and 4 bit, bitmaps contain a colour palette. The colour palette has blue, green, red and reserved components each 1 byte in size. // Colour palette struct BGRQuad { UInt8 blue; UInt8 green; UInt8 red; UInt8 reserved; }; The problem I am having is when I create a vector of the BGRQuad structure I can no longer use the ifstream read function to load data from the file directly into the BGRQuad vector. // This code throws an assert failure! std::vecotr quads; if (coloursUsed) // colour table available { // read in the colours quads.reserve(coloursUsed); inFile.read( reinterpret_cast(&quads[0]), coloursUsed * sizeof(BGRQuad) ); } Does anyone know how to read directly into the vector without having to create a C array and copy data into the BGRQuad vector?

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• Linking Apache to Tomcat with multiple domains.

  - by Royce Thigpen

  Okay, so I've been working for a while on this, and have been searching, but so far I have not found any answers that actually answer what I want to know. I'm a little bit at the end of my rope with this one, but I'm hoping I can figure this out sometime soon. So I have Apache 2 installed and serving up standard webpages, but I also have that linked to a Tomcat instance for one of my domains currently supported. However, I want to add another domain to the server via Apache that points to a separate code base from the one I already have. I have been coming at this from several different angles, and I have determined that I just don't know enough about setting up these servers to really do what I want to do. Little information on my server: Currently running a single Tomcat5.5 instance with Apache 2, using mod_jk to connect them together. I have a worker in workers.properties that points it's "host" field to "localhost" with the correct port my Tomcat instance, so that all works. In my Tomcat server.xml file, I have a host defined as "localhost" that points at my webapp that I am currently serving up, with that host set as the defaultHost as well. One thought I had was that I could add a new worker with a different host than "localhost" (i.e. host2) and then define a new host in my server.xml file called "host2" to match it, but after reading around some on the internet, It seems the "host" of the worker must point to a server, and not a hostname in the Tomcat instance, is this correct? Again, a simple rundown of what I want: Setup in apache/tomcat combo such that www.domain1.com points at "webapp1" and www.domain2.com points at "webapp2".

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• How to copy files without slowing down my app?

  - by Kevin Gebhardt

  I have a bunch of little files in my assets which need to be copied to the SD-card on the first start of my App. The copy code i got from here placed in an IntentService works like a charm. However, when I start to copy many litte files, the whole app gets increddible slow (I'm not really sure why by the way), which is a really bad experience for the user on first start. As I realised other apps running normal in that time, I tried to start a child process for the service, which didn't work, as I can't acess my assets from another process as far as I understood. Has anybody out there an idea how a) to copy the files without blocking my app b) to get through to my assets from a private process (process=":myOtherProcess" in Manifest) or c) solve the problem in a complete different way Edit: To make this clearer: The copying allready takes place in a seperate thread (started automaticaly by IntentService). The problem is not to separate the task of copying but that the copying in a dedicated thread somehow affects the rest of the app (e.g. blocking to many app-specific resources?) but not other apps (so it's not blocking the whole CPU or someting) Edit2: Problem solved, it turns out, there wasn't really a problem. See my answer below.

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• "Finding" an object instance of a known class?

  - by Sean C

  My first post here (anywhere for that matter!), re. Cocoa/Obj-C (I'm NOT up to speed on either, please be patient!). I hope I haven't missed the answer already, I did try to find it. I'm an old-school procedural dog (haven't done any programming since the mid 80's, so I probably just can't even learn new tricks), but OOP has my head spinning! My question is: is there any means at all to "discover/find/identify" an instance of an object of a known class, given that some OTHER unknown process instantiated it? eg. somthing that would accomplish this scenario: (id) anObj = [someTarget getMostRecentInstanceOf:[aKnownClass class]]; for that matter, "getAnyInstance" or "getAllInstances" might do the trick too. Background: I'm trying to write a plugin for a commercial application, so much of the heavy lifting is being done by the app, behind the scenes. I have the SDK & header files, I know what class the object is, and what method I need to call (it has only instance methods), I just can't identify the object for targetting. I've spent untold hours and days going over Apples documentation, tutorials and lots of example/sample code on the web (including here at Stack Overflow), and come up empty. Seems that everything requires a known target object to work, and I just don't have one. Since I may not be expressing my problem as clearly as needed, I've put up a web page, with diagram & working sample pages to illustrate: http://www.nulltime.com/svtest/index.html Any help or guidance will be appreciated! Thanks.

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• How do I make a HTTP POST request to an url from within a c++ dll?

  - by tjorriemorrie

  Hi, there's an open-source application I need to use. It allows you to use a custom dll. Unfortunately, I can't code c++; i don't like it; it don't want to learn it. I do know PHP very well however, thus you can see that I'll rather do my logic within a PHP application. Thus I'm thinking about posting the data from c++/dll to a url on my localhost. (i have my local server set up, that's not the problem). I need to post a large amount of variables (thus a POST and not GET request required). The return value will only be one (int)variable, either 0, 1 or 2. So I need a c++ function that: 1) will post variables to an url. 2) Wait for, and receive the answer. The data type can be in xml, soap, json, whatever, doesn't matter. Is there anyone that can write a little c++ http function for me? pretty please? ;)

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• Convert long/lat to pixel x/y on a given picure.

  - by Kalinin

  I have a city "map" (for example - Moscow). She in accuracy repeats the contours the given city in google maps (that is it is copied from google maps and it is a little processed, but the sense remained the same). Also I have object co-ordinates in a city (in co-ordinates of google). Problem: how to convert google co-ordinates to the co-ordinates of my picture (that is in pixels on OX and OY on a picture). That is I receive google-co-ordinates and it is necessary for me to draw this point on my picture. The most desired variant of the answer - is based on javascript, but it is possible and on php. I know that on small scales (for example on city scales) it to make simply enough (it is necessary to learn what google-co-ordinates has one of picture corners, then to learn "price" of one pixel in google-co-ordinates on a picture on axes OX and OY separately). But on the big scales (country scale) "price" of one pixel will be not a constant, and will vary strongly enough and the method described above cannot be applied. How to solve a problem on country scales?

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• Type errors when using same name

  - by lykimq

  I have 3 files: 1) cpf0.ml type string = char list type url = string type var = string type name = string type symbol = | Symbol_name of name 2) problem.ml: type symbol = | Ident of string 3) test.ml open Problem;; open Cpf0;; let symbol b = function | Symbol_name n -> Ident n When I combine test.ml: ocamlc -c test.ml. I received an error: This expression has type Cpf0.name = char list but an expression was expected of type string Could you please help me to correct it? Thank you very much EDIT: Thank you for your answer. I want to explain more about these 3 files: Because I am working with extraction in Coq to Ocaml type: cpf0.ml is generated from cpf.v : Require Import String. Definition string := string. Definition name := string. Inductive symbol := | Symbol_name : name -> symbol. The code extraction.v: Set Extraction Optimize. Extraction Language Ocaml. Require ExtrOcamlBasic ExtrOcamlString. Extraction Blacklist cpf list. where ExtrOcamlString I opened: open Cpf0;; in problem.ml, and I got a new problem because in problem.ml they have another definition for type string This expression has type Cpf0.string = char list but an expression was expected of type Util.StrSet.elt = string Here is a definition in util.ml defined type string: module Str = struct type t = string end;; module StrOrd = Ord.Make (Str);; module StrSet = Set.Make (StrOrd);; module StrMap = Map.Make (StrOrd);; let set_add_chk x s = if StrSet.mem x s then failwith (x ^ " already declared") else StrSet.add x s;; I was trying to change t = string to t = char list, but if I do that I have to change a lot of function it depend on (for example: set_add_chk above). Could you please give me a good idea? how I would do in this case.

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• How do I grep for entire, possibly wrapped, lines of code?

  - by NXT

  When searching code for strings, I constantly run into the problem that I get meaningless, context-less results. For example, if a function call is split across 3 lines, and I search for the name of a parameter, I get the parameter on a line by itself and not the name of the function. For example, in a file containing ... someFunctionCall ("test", MY_CONSTANT, (some *really) - long / expression); grepping for MY_CONSTANT would return a line that looked like this: MY_CONSTANT, Likewise, in a comment block: ///////////////////////////////////////// // FIXMESOON, do..while is the wrong choice here, because // it makes the wrong thing happen ///////////////////////////////////////// Grepping for FIXMESOON gives the very frustrating answer: // FIXMESOON, do..while is the wrong choice here, because When there are thousands of hits, single line results are a little meaningless. What I would like to do is have grep be aware of the start and stop points of source code lines, something as simple as having it consider ";" as the line separator would be a good start. Bonus points if you can make it return the entire comment block if the hit is inside a comment. I know you can't do this with grep alone. I also am aware of the option to have grep return a certain number of lines of content. Any suggestions on how to accomplish under Linux? FYI my preferred languages are C and Perl. I'm sure I could write something, but I know that somebody must have already done this. Thanks!

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• Strict pointer aliasing: is access through a 'volatile' pointer/reference a solution?

  - by doublep

  On the heels of a specific problem, a self-answer and comments to it, I'd like to understand if it is a proper solution, workaround/hack or just plain wrong. Specifically, I rewrote code: T x = ...; if (*reinterpret_cast <int*> (&x) == 0) ... As: T x = ...; if (*reinterpret_cast <volatile int*> (&x) == 0) ... with a volatile qualifier to the pointer. Let's just assume that treating T as int in my situation makes sense. Does this accessing through a volatile reference solve pointer aliasing problem? For a reference, from specification: [ Note: volatile is a hint to the implementation to avoid aggressive optimization involving the object because the value of the object might be changed by means undetectable by an implementation. See 1.9 for detailed semantics. In general, the semantics of volatile are intended to be the same in C++ as they are in C. — end note ] EDIT: The above code did solve my problem at least on GCC 4.5.

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• Jquery toggle event is messing with checkbox value

  - by John McCollum

  Hi all, I'm using Jquery's toggle event to do some stuff when a user clicks a checkbox, like this: $('input#myId').toggle( function(){ //do stuff }, function(){ //do other stuff } ); The problem is that the checkbox isn't being ticked when I click on the checkbox. (All the stuff I've put into the toggle event is working properly.) I've tried the following: $('input#myId').attr('checked', 'checked'); and $(this).attr('checked', 'checked'); and even simply return true; But nothing is working. Can anyone tell me where I'm going wrong? Edit - thanks to all who replied. Dreas' answer very nearly worked for me, except for the part that checked the attribute. This works perfectly (although it's a bit hacky) $('input#myInput').change(function () { if(!$(this).hasClass("checked")) { //do stuff if the checkbox isn't checked $(this).addClass("checked"); return; } //do stuff if the checkbox isn't checked $(this).removeClass('checked'); }); Thanks again to all who replied.

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• Help with SQL query (Calculate a ratio between two entitiess)

  - by Mestika

  Hi, I’m going to calculate a ratio between two entities but are having some trouble with the query. The principal is the same to, say a forum, where you say: A user gets points for every new thread. Then, calculate the ratio of points for the number of threads. Example: User A has 300 points. User A has started 6 thread. The point ratio is: 50:6 My schemas look as following: student(studentid, name, class, major) course(courseid, coursename, department) courseoffering(courseid, semester, year, instructor) faculty(name, office, salary) gradereport(studentid, courseid, semester, year, grade) The relations is a following: Faculity(name) = courseoffering(instructor) Student(studentid) = gradereport (studentid) Courseoffering(courseid) = course(courseid) Gradereport(courseid) = courseoffering(courseid) I have this query to select the faculty names there is teaching one or more students: SELECT COUNT(faculty.name) FROM faculty, courseoffering, gradereport, student WHERE faculty.name = courseoffering.instructor AND courseoffering.courseid = gradereport.courseid AND gradereport.studentid = student.studentid My problem is to find the ratio between the faculty members salary in regarding to the number of students they are teaching. Say, a teacher get 10.000 in salary and teaches 5 students, then his ratio should be 1:5. I hope that someone has an answer to my problem and understand what I'm having trouble with. Thanks Mestika

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• Loading child entities with JPA on Google App Engine

  - by Phil H

  I am not able to get child entities to load once they are persisted on Google App Engine. I am certain that they are saving because I can see them in the datastore. For example if I have the following two entities. public class Parent implements Serializable{ @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Extension(vendorName="datanucleus", key="gae.encoded-pk", value="true") private String key; @OneToMany(cascade=CascadeType.ALL) private List<Child> children = new ArrayList<Child>(); //getters and setters } public class Child implements Serializable{ @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Extension(vendorName="datanucleus", key="gae.encoded-pk", value="true") private String key; private String name; @ManyToOne private Parent parent; //getters and setters } I can save the parent and a child just fine using the following: Parent parent = new Parent(); Child child = new Child(); child.setName("Child Object"); parent.getChildren().add(child); em.persist(parent); However when I try to load the parent and then try to access the children (I know GAE lazy loads) I do not get the child records. //parent already successfully loaded parent.getChildren.size(); // this returns 0 I've looked at tutorial after tutorial and nothing has worked so far. I'm using version 1.3.3.1 of the SDK. I've seen the problem mentioned on various blogs and even the App Engine forums but the answer is always JDO related. Am I doing something wrong or has anyone else had this problem and solved it for JPA?

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• Testing When Correctness is Poorly Defined?

  - by dsimcha

  I generally try to use unit tests for any code that has easily defined correct behavior given some reasonably small, well-defined set of inputs. This works quite well for catching bugs, and I do it all the time in my personal library of generic functions. However, a lot of the code I write is data mining code that basically looks for significant patterns in large datasets. Correct behavior in this case is often not well defined and depends on a lot of different inputs in ways that are not easy for a human to predict (i.e. the math can't reasonably be done by hand, which is why I'm using a computer to solve the problem in the first place). These inputs can be very complex, to the point where coming up with a reasonable test case is near impossible. Identifying the edge cases that are worth testing is extremely difficult. Sometimes the algorithm isn't even deterministic. Usually, I do the best I can by using asserts for sanity checks and creating a small toy test case with a known pattern and informally seeing if the answer at least "looks reasonable", without it necessarily being objectively correct. Is there any better way to test these kinds of cases?

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• Forwarding HTTP Request with Direct Server Return

  - by Daniel Crabtree

  I have servers spread across several data centers, each storing different files. I want users to be able to access the files on all servers through a single domain and have the individual servers return the files directly to the users. The following shows a simple example: 1) The user's browser requests http://www.example.com/files/file1.zip 2) Request goes to server A, based on the DNS A record for example.com. 3) Server A analyzes the request and works out that /files/file1.zip is stored on server B. 4) Server A forwards the request to server B. 5) Server B returns file1.zip directly to the user without going through server A. Note: steps 4 and 5 must be transparent to the user and cannot involve sending a redirect to the user as that would violate the requirement of a single domain. From my research, what I want to achieve is called "Direct Server Return" and it is a common setup for load balancing. It is also sometimes called a half reverse proxy. For step 4, it sounds like I need to do MAC Address Translation and then pass the request back onto the network and for servers outside the network of server A tunneling will be required. For step 5, I simply need to configure server B, as per the real servers in a load balancing setup. Namely, server B should have server A's IP address on the loopback interface and it should not answer any ARP requests for that IP address. My problem is how to actually achieve step 4? I have found plenty of hardware and software that can do this for simple load balancing at layer 4, but these solutions fall short and cannot handle the kind of custom routing I require. It seems like I will need to roll my own solution. Ideally, I would like to do the routing / forwarding at the web server level, i.e. in PHP or C# / ASP.net. However, I am open to doing it at a lower level such as Apache or IIS, or at an even lower level, i.e. a custom proxy service in front of everything.

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• implementing a Intelligent File Transfer Software in java over TCP/IP

  - by whyjava

  Hello I am working on a proposal where we have to implement a software which can move files between one source to destination.The overall goal of this project is to create intelligent file transfer.This software will have three components :- 1) Broker : Broker is the module that communicates with other brokers, monitors files, moves files, retrieves configurations from the Configuration Manager, supplies process information for the monitor, archives files, writes all process data to log files and escalates issues if necessary 2) Configuration Manager :Configuration Manager is a web-based application used to configure and deploy the configuration to all brokers. 3) Monitor : Monitor is a web-based application used to monitor each Broker in the environment. This project has to be built up in java and protocol for file transfer in tcp/ip. Client does not want to use FTP. File Transfer seems very easy, until there are several processes who are waiting to pick the file up automatically. Several problems arise: How can we guarantee the file is received at the destination? If a file isn’t received the first time, we should try it again (even after a restart or power breakdown) ? How does the receiver knows the file that is received is complete? How can we transfer multiple files synchronously? How can we protect the bandwidth, so file transfer isn’t blocking other processes? How does one interoperate between multiple OS platforms? What about authentication? How can we monitor het workflow? Auditing / logging Archiving Can you please provide answer to some of these? Thanks

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• Should I use a binary or a text file for storing protobuf messages?

  - by nbolton

  Using Google protobuf, I am saving my serialized messaged data to a file - in each file there are several messages. We have both C++ and Python versions of the code, so I need to use protobuf functions that are available in both languages. I have experimented with using SerializeToArray and SerializeAsString and there seems to be the following unfortunate conditions: SerializeToArray: As suggested in one answer, the best way to use this is to prefix each message with it's data size. This would work great for C++, but in Python it doesn't look like this is possible - am I wrong? SerializeAsString: This generates a serialized string equivalent to it's binary counterpart - which I can save to a file, but what happens if one of the characters in the serialization result is \n - how do we find line endings, or the ending of messages for that matter? Update: Please allow me to rephrase slightly. As I understand it, I cannot write binary data in C++ because then our Python application cannot read the data, since it can only parse string serialized messages. Should I then instead use SerializeAsString in both C++ and Python? If yes, then is it best practice to store such data in a text file rather than a binary file? My gut feeling is binary, but as you can see this doesn't look like an option.

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• Converting Single dimensional vector or array to two dimension in Matlab

  - by pac

  Well I do not know if I used the exact term. I tried to find an answer on the net. Here is what i need: I have a vector a = 1 4 7 2 5 8 3 6 9 If I do a(4) the value is 4. So it is reading first column top to buttom then continuing to next .... I don't know why. However, What I need is to call it using two indices. As row and column: a(3,2)= 4 or even better if i can call it in the following way: a{3}(2)=4 What is this process really called (want to learn) and how to perform in matlab. I thought of a loop. Is there a built in function Thanks a lot Check this: a = 18 18 16 18 18 18 16 0 0 0 16 16 18 0 18 16 0 18 18 16 18 0 18 18 0 16 0 0 0 18 18 0 18 18 16 0 16 0 18 18 >> a(4) ans = 18 >> a(5) ans = 18 >> a(10) ans = 18 I tried reshape. it is reshaping not converting into 2 indeces

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• Accessing program information that gdb sees in C++

  - by anon

  I have a program written in C++, on Linux, compiled with -g. When I run it under gdb, I can 1) set breakpoints 2) at those breakpoints, print out variables 3) see the stackframe 4) given a variable that's a structure, print out parts of the structure (i.e. how ddd displays information). Now, given that my program is compiled with "-g" -- is there anyway that I can access this power within my program itself? I.e. given that my program is compiled with "-g", is there some std::vector<string> getStackFrame(); function I can call to get the current stackframe at the current point of execution? Given a pointer to an object and it's type ... can I do std::vector getClassMember(class_name); ? I realize the default answer is "no, C++ doesn't support that level of introspection" -- however, recall I'm on linux, my program is compiled with "-g", and gdb can do it, so clearly the inforamtion is there. Question is: is there some API for accessing it? EDIT: PS Naysers, I'd love to see a reason for closing this question.

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