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  • What is the best approach for creating a Common Information Model?

    - by Kaiser Advisor
    Hi, I would like to know the best approach to create a Common Information Model. Just to be clear, I've also heard it referred to as a canonical information model, semantic information model, and master data model - As far as I can tell, they are all referring to the same concept. I've heard in the past that a combined "top-down" and "bottom-up" approach is best. This has the advantage of incorporating "Ivory tower" architects and developers - The work will meet somewhere in the middle and usually be both logical and practical. However, this involves bringing in a lot of people with different skill sets. I've also seen a couple of references to the Distributed Management Task Force, but I can't glean much on best practices in terms of CIM development. This is something I'm quite interested in getting some feedback on since having a strong CIM is a prerequisite to SOA. Thanks for your help! KA Update I've heard another strategy goes along with overall SOA implementation: Get the business involved, and seek executive sponsorship. This would be part of the "Top-down" effort.

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  • InstallExecuteSequence cache interferes with custom action operation

    - by Dima G
    I need to upgrade a product that could be installed in per-user context to a new version that is always in per-machine context. The requirements are: Whether the old version was installed in a Per-User (no matter who) or Per-Machine context should be completely seamless to an administrator user that performs the upgrade. The MSI upgrade should succeed without the need to know the password of the user that originally installed the previous version of the product in a Per-User context. The installation should be performed from a single .msi file (no setup.exe is allowed). The installation should be able to run in a silent (non-UI) mode. No reboots are allowed during installation. My strategy is to find in the beginning of the installation whether the product is already installed in per-user context, and if so, to transform the registry keys manually to Per-Machine context (I checked: no additional changes such as file system changes etc. are needed except this transform). I figured out how to move all appropriate keys in the registry from the user settings to the machine settings (pre-loaded appropriate user hive in case it didn't appear in HKEY_USERS) and created custom action that does it - and it does work when I run it as a stand-alone executable before running the MSI. The problem, however, is that when Windows Installer runs InstallExecuteSequence it first creates a 'cached product context' for all products. So when my custom action runs in the course of InstallExecuteSequence, this cache has already been created. Thus FindRelatedProducts action that determines if older product with same upgrade code exists looks on that cache and ignores the changes that my custom action applied. If before running the MSI the previous product was in per-user context, FindRelatedProducts will look at the cache and not apply the upgrade and remove the previous version, because the new product is in per-machine context, even though the previous product version is already configured to per-machine context in the registry by that time by my custom action. What can be done to solve this problem without violating the requirements stated above?

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  • Is there a way to easily convert a series of tarballs of a source tree into a git repository?

    - by Hotei
    I'm new to git and I have a moderately large number of weekly tarballs from a long running project. Each tarball has on average a few hundred files in it. I'm looking for a git strategy that will allow me to add the expanded contents of each tarball to a new git repository, starting from version 1.001 and going through version 1.650. As of this stage of the project 99.5% of tarball(n) is just a copy of version(n-1) - in other words, a perfect candidate for git. The desired end result is to have only the master branch remaining at the end of the process. I think I know git well enough to do this "by hand". As I understand it there is no possibility of a merge conflict since there will be no opportunity to change the master before the next version is added and committed. A shell script is my first guess, but I'm not sure how well bash will like it when git checkout branch_n gets processed while bash is executing in branch_n-1. For the purposes of this project the host environment is Ubuntu 10.4, resources available are 8 Gig RAM, 500 Gig Disk space free and 4 CPU processor at 3.ghz . I don't need someone else to solve the problem but I could use a nudge in the right direction as to how a git expert would approach it. Any advice from someone who's "been there done that" would be appreciated. Hotei PS: I have looked at site's suggested "related questions" and found nothing relevant.

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  • Hibernate design to speed up querying of large dataset

    - by paddydub
    I currently have the below tables representing a bus network mapped in hibernate, accessed from a Spring MVC based bus route planner I'm trying to make my route planner application perform faster, I load all the above tables into Lists to perform the route planner logic. I would appreciate if anyone has any ideas of how to speed my performace Or any suggestions of another method to approach this problem of handling a large set of data Coordinate Connections Table (INT,INT,INT, DOUBLE)( Containing 50,000 Coordinate Connections) ID, FROMCOORDID, TOCOORDID, DISTANCE 1 1 2 0.383657 2 1 17 0.173201 3 1 63 0.258781 4 1 64 0.013726 5 1 65 0.459829 6 1 95 0.458769 Coordinate Table (INT,DECIMAL, DECIMAL) (Containing 4700 Coordinates) ID , LAT, LNG 0 59.352669 -7.264341 1 59.352669 -7.264341 2 59.350012 -7.260653 3 59.337585 -7.189798 4 59.339221 -7.193582 5 59.341408 -7.205888 Bus Stop Table (INT, INT, INT)(Containing 15000 Stops) StopID RouteID COORDINATEID 1000100001 100 17 1000100002 100 18 1000100003 100 19 1000100004 100 20 1000100005 100 21 1000100006 100 22 1000100007 100 23 This is how long it takes to load all the data from each table: stop.findAll = 148ms, stops.size: 15670 Hibernate: select coordinate0_.COORDINATEID as COORDINA1_2_, coordinate0_.LAT as LAT2_, coordinate0_.LNG as LNG2_ from COORDINATES coordinate0_ coord.findAll = 51ms , coordinates.size: 4704 Hibernate: select coordconne0_.COORDCONNECTIONID as COORDCON1_3_, coordconne0_.DISTANCE as DISTANCE3_, coordconne0_.FROMCOORDID as FROMCOOR3_3_, coordconne0_.TOCOORDID as TOCOORDID3_ from COORDCONNECTIONS coordconne0_ coordinateConnectionDao.findAll = 238ms ; coordConnectioninates.size:48132 Hibernate Annotations @Entity @Table(name = "STOPS") public class Stop implements Serializable { @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "STOPID") private int stopID; @Column(name = "ROUTEID", nullable = false) private int routeID; @ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "COORDINATEID", nullable = false) private Coordinate coordinate; } @Table(name = "COORDINATES") public class Coordinate { @Id @GeneratedValue @Column(name = "COORDINATEID") private int CoordinateID; @Column(name = "LAT") private double latitude; @Column(name = "LNG") private double longitude; } @Entity @Table(name = "COORDCONNECTIONS") public class CoordConnection { @Id @GeneratedValue @Column(name = "COORDCONNECTIONID") private int CoordinateID; @ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "FROMCOORDID", nullable = false) private Coordinate fromCoordID; @ManyToOne(fetch = FetchType.LAZY) @JoinColumn(name = "TOCOORDID", nullable = false) private Coordinate toCoordID; @Column(name = "DISTANCE", nullable = false) private double distance; }

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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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  • Truncate portions of a string to limit the whole string's length in Ruby

    - by Horace Loeb
    Suppose you want to generate dynamic page titles that look like this: "It was all a dream, I used to read word up magazine" from "Juicy" by The Notorious B.I.G I.e., "LYRICS" from "SONG_NAME" by ARTIST However, your title can only be 69 characters total and this template will sometimes generate titles that are longer. One strategy for solving this problem is to truncate the entire string to 69 characters. However, a better approach is to truncate the less important parts of the string first. I.e., your algorithm might look something like this: Truncate the lyrics until the entire string is <= 69 characters If you still need to truncate, truncate the artist name until the entire string is <= 69 characters If you still need to truncate, truncate the song name until the entire string is <= 69 characters If all else fails, truncate the entire string to 69 characters Ideally the algorithm would also limit the amount each part of the string could be truncated. E.g., step 1 would really be "Truncate the lyrics to a minimum of 10 characters until the entire string is <= 69 characters" Since this is such a common situation, I was wondering if someone has a library or code snippet that can take care of it.

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  • Saving Abstract and Sub classes to database

    - by bretddog
    Hi, I have an abstract class "StrategyBase", and a set of sub classes, StrategyA/B/C etc. The sub classes use some of the properties of the base class, and have some individual properties. My question is how to save this to a database. I'm currently using SqlCE, and Linq-To-Sql by creating entity classes automatically with SqlMetal.exe. I've seen there are three solutions shown in this question, but I'm not able to see how these solutions will work or not with SqlMetal/entity classes. Though it seems to me the "concrete table inheritance" would probably work without any manual modifying. What about the other two, would they be problematic? For "Single Table Inheritance" wouldn't all classes get all variables, even though they don't need them? And for the "Class table inheritance" solution I can't really see at all how that will map into the entity-classes for a useful purpose. I may note that I extend these partial entity classes for making the classes of my business objects. I may also consider moving to EntityFramework instead of SqlMetal/Linq2Sql, so would be nice also to know if that makes any difference to what schema is easy to implement. One likely important thing to note is that I will constantly be develop new strategies, which makes me have to modify the program code, and probably the database shcema; when adding a new strategy. Sorry the question is a bit "all over the place", but hopefully it's some clear advantages/disadvantages here that you may be able to advice. ? Cheers!

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  • Image drawing library for Haskell?

    - by absz
    I'm working on a Haskell program for playing spatial games: I have a graph of a bunch of "individuals" playing the Prisoner's Dilemma, but only with their immediate neighbors, and copying the strategies of the people who do best. I've reached a point where I need to draw an image of the world, and this is where I've hit problems. Two of the possible geometries are easy: if people have four or eight neighbors each, then I represent each one as a filled square (with color corresponding to strategy) and tile the plane with these. However, I also have a situation where people have six neighbors (hexagons) or three neighbors (triangles). My question, then, is: what's a good Haskell library for creating images and drawing shapes on them? I'd prefer that it create PNGs, but I'm not incredibly picky. I was originally using Graphics.GD, but it only exports bindings to functions for drawing points, lines, arcs, ellipses, and non-rotated rectangles, which is not sufficient for my purposes (unless I want to draw hexagons pixel by pixel*). I looked into using foreign import, but it's proving a bit of a hassle (partly because the polygon-drawing function requires an array of gdPoint structs), and given that my requirements may grow, it would be nice to use an in-Haskell solution and not have to muck about with the FFI (though if push comes to shove, I'm willing to do that). Any suggestions? * That is also an option, actually; any tips on how to do that would also be appreciated, though I think a library would be easier.

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  • Java application design question

    - by ring bearer
    I have a hobby project, which is basically to maintain 'todo' tasks in the way I like. One task can be described as: public class TodoItem { private String subject; private Date dueBy; private Date startBy; private Priority priority; private String category; private Status status; private String notes; } As you can imagine I would have 1000s of todo items at a given time. What is the best strategy to store a todo item? (currently on an XML file) such that all the items are loaded quickly up on app start up(the application shows kind of a dashboard of all the items at start up)? What is the best way to design its back-end so that it can be ported to Android/or a J2ME based phone? Currently this is done using Java Swing. What should I concentrate on so that it works efficiently on a device where memory is limited? The application throws open a form to enter new todo task. For now, I would like to save the newly added task to my-todos.xml once the user presses "save" button. What are the common ways to append such a change to an existing XML file?(note that I don't want to read the whole file again and then persist)

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  • Javascript function to add class to a list element based on # in url.

    - by Jason
    I am trying to create a javascript function to add and remove a class to a list element based on the #tag at the end of the url on a page. The page has several different states, each with a different # in the url. I am currently using this script to change the style of a given element based on the # in the url when the user first loads the page, however if the user navigates to a different section of the page the style added on the page load stays, I would like it to change. <script type="text/javascript"> var hash=location.hash.substring(1); if (hash == 'strategy'){ document.getElementById('strategy_link').style.backgroundPosition ="-50px"; } if (hash == 'branding'){ document.getElementById('branding_link').style.backgroundPosition ="-50px"; } if (hash == 'marketing'){ document.getElementById('marketing_link').style.backgroundPosition ="-50px"; } if (hash == 'media'){ document.getElementById('media_link').style.backgroundPosition ="-50px"; } if (hash == 'management'){ document.getElementById('mangement_link').style.backgroundPosition ="-50px"; } if (hash == ''){ document.getElementById('shop1').style.display ="block"; } </script> Additionally, I am using a function to change the class of the element onClick, but when a user comes to a specific # on the page directly from another page and then clicks to a different location, two elements appear active. <script type="text/javascript"> function selectInList(obj) { $("#circularMenu").children("li").removeClass("highlight"); $(obj).addClass("highlight"); } </script> You can see this here: http://www.perksconsulting.com/dev/capabilities.php#branding Thanks.

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  • How do I dispatch to a method based on a parameter's runtime type in C# < 4?

    - by Evan Barkley
    I have an object o which guaranteed at runtime to be one of three types A, B, or C, all of which implement a common interface I. I can control I, but not A, B, or C. (Thus I could use an empty marker interface, or somehow take advantage of the similarities in the types by using the interface, but I can't add new methods or change existing ones in the types.) I also have a series of methods MethodA, MethodB, and MethodC. The runtime type of o is looked up and is then used as a parameter to these methods. public void MethodA(A a) { ... } public void MethodB(B b) { ... } public void MethodC(C c) { ... } Using this strategy, right now a check has to be performed on the type of o to determine which method should be invoked. Instead, I would like to simply have three overloaded methods: public void Method(A a) { ... } // these are all overloads of each other public void Method(B b) { ... } public void Method(C c) { ... } Now I'm letting C# do the dispatch instead of doing it manually myself. Can this be done? The naive straightforward approach doesn't work, of course: Cannot resolve method 'Method(object)'. Candidates are: void Method(A) void Method(B) void Method(C)

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  • Consecutive Tables in Latex

    - by Tim
    Hi, I wonder how to place several tables consecutively in Latex? The page with the text right before the first table has a little space but not enough for the first table, so the first table is to be placed on the top of the next page, although I use "\begin{table}[!h]" for it. The second table does not fit into the place in the rest of the page of the first table, so I think I might use longtable for it to span the rest of the page and the top of the next page. Similarly, I use longtable for the third table. The latex code is as follows: ... % some text \begin{table}[!h] \caption{Table 1. \label{tab:1}} \begin{center} \begin{tabular}{c c} ... \end{tabular} \end{center} \end{table} \begin{center} \begin{longtable}{ c c } \caption{Table 2. \label{tab:2}}\\ ... \end{longtable} \end{center} \begin{center} \begin{longtable}{ c c } \caption{Table 3. \label{tab:3}}\\ ... \end{longtable} \end{center} ... % some text In the compiled pdf file it turns out that the order of the tables is messed up. The first table is placed behind the second and third one, and the second one spans the page with text before the tables and the next page with the third one following it. I would like to know how I can make the three tables appear consecutively in order, and there are no space left blank between them and between the text and the tables? Or if what I hope is not possible, what is the best strategy then? Thanks and regards! EDIT: Removing [!h] does not make improvement, the first table is still behind the second and the third.

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  • How can I SETF an element in a tree by an accessor?

    - by Willi Ballenthin
    We've been using Lisp in my AI course. The assignments I've received have involved searching and generating tree-like structures. For each assignment, I've ended up writing something like: (defun initial-state () (list 0 ; score nil ; children 0 ; value 0)) ; something else and building my functions around these "states", which are really just nested lists with some loosely defined structure. To make the structure more rigid, I've tried to write accessors, such as: (defun state-score ( state ) (nth 2 state)) This works for reading the value (which should be all I need to do in a nicely functional world. However, as time crunches, and I start to madly hack, sometimes I want a mutable structure). I don't seem to be able to SETF the returned ...thing (place? value? pointer?). I get an error with something like: (setf (state-score *state*) 10) Sometimes I seem to have a little more luck writing the accessor/mutator as a macro: (defmacro state-score ( state ) `(nth 2 ,state)) However I don't know why this should be a macro, so I certainly shouldn't write it as a macro (except that sometimes it works. Programming by coincidence is bad). What is an appropriate strategy to build up such structures? More importantly, where can I learn about whats going on here (what operations affect the memory in what way)?

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  • How to implement Horner's scheme for multivariate polynomials?

    - by gsreynolds
    Background I need to solve polynomials in multiple variables using Horner's scheme in Fortran90/95. The main reason for doing this is the increased efficiency and accuracy that occurs when using Horner's scheme to evaluate polynomials. I currently have an implementation of Horner's scheme for univariate/single variable polynomials. However, developing a function to evaluate multivariate polynomials using Horner's scheme is proving to be beyond me. An example bivariate polynomial would be: 12x^2y^2+8x^2y+6xy^2+4xy+2x+2y which would factorised to x(x(y(12y+8))+y(6y+4)+2)+2y and then evaluated for particular values of x & y. Research I've done my research and found a number of papers such as: staff.ustc.edu.cn/~xinmao/ISSAC05/pages/bulletins/articles/147/hornercorrected.pdf citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.40.8637&rep=rep1&type=pdf www.is.titech.ac.jp/~kojima/articles/B-433.pdf Problem However, I'm not a mathematician or computer scientist, so I'm having trouble with the mathematics used to convey the algorithms and ideas. As far as I can tell the basic strategy is to turn a multivariate polynomial into separate univariate polynomials and compute it that way. Can anyone help me? If anyone could help me turn the algorithms into pseudo-code that I can implement into Fortran myself, I would be very grateful.

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  • Fluently setting C# properties and chaining methods

    - by John Feminella
    I'm using .NET 3.5. We have some complex third-party classes which are automatically generated and out of my control, but which we must work with for testing purposes. I see my team doing a lot of deeply-nested property getting/setting in our test code, and it's getting pretty cumbersome. To remedy the problem, I'd like to make a fluent interface for setting properties on the various objects in the hierarchical tree. There are a large number of properties and classes in this third-party library, and it would be too tedious to map everything manually. My initial thought was to just use object initializers. Red, Blue, and Green are properties, and Mix() is a method that sets a fourth property Color to the closest RGB-safe color with that mixed color. Paints must be homogenized with Stir() before they can be used. Bucket b = new Bucket() { Paint = new Paint() { Red = 0.4; Blue = 0.2; Green = 0.1; } }; That works to initialize the Paint, but I need to chain Mix() and other methods to it. Next attempt: Create<Bucket>(Create<Paint>() .SetRed(0.4) .SetBlue(0.2) .SetGreen(0.1) .Mix().Stir() ) But that doesn't scale well, because I'd have to define a method for each property I want to set, and there are hundreds of different properties in all the classes. Also, C# doesn't have a way to dynamically define methods prior to C# 4, so I don't think I can hook into things to do this automatically in some way. Third attempt: Create<Bucket>(Create<Paint>().Set(p => { p.Red = 0.4; p.Blue = 0.2; p.Green = 0.1; }).Mix().Stir() ) That doesn't look too bad, and seems like it'd be feasible. Is this an advisable approach? Is it possible to write a Set method that works this way? Or should I be pursuing an alternate strategy?

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  • Lost with hibernate - OneToMany resulting in the one being pulled back many times..

    - by Andy
    I have this DB design: CREATE TABLE report ( ID MEDIUMINT PRIMARY KEY NOT NULL AUTO_INCREMENT, user MEDIUMINT NOT NULL, created TIMESTAMP NOT NULL, state INT NOT NULL, FOREIGN KEY (user) REFERENCES user(ID) ON UPDATE CASCADE ON DELETE CASCADE ); CREATE TABLE reportProperties ( ID MEDIUMINT NOT NULL, k VARCHAR(128) NOT NULL, v TEXT NOT NULL, PRIMARY KEY( ID, k ), FOREIGN KEY (ID) REFERENCES report(ID) ON UPDATE CASCADE ON DELETE CASCADE ); and this Hibernate Markup: @Table(name="report") @Entity(name="ReportEntity") public class ReportEntity extends Report{ @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name="ID") private Integer ID; @Column(name="user") private Integer user; @Column(name="created") private Timestamp created; @Column(name="state") private Integer state = ReportState.RUNNING.getLevel(); @OneToMany(mappedBy="pk.ID", fetch=FetchType.EAGER) @JoinColumns( @JoinColumn(name="ID", referencedColumnName="ID") ) @MapKey(name="pk.key") private Map<String, ReportPropertyEntity> reportProperties = new HashMap<String, ReportPropertyEntity>(); } and @Table(name="reportProperties") @Entity(name="ReportPropertyEntity") public class ReportPropertyEntity extends ReportProperty{ @Embeddable public static class ReportPropertyEntityPk implements Serializable{ /** * long#serialVersionUID */ private static final long serialVersionUID = 2545373078182672152L; @Column(name="ID") protected int ID; @Column(name="k") protected String key; } @EmbeddedId protected ReportPropertyEntityPk pk = new ReportPropertyEntityPk(); @Column(name="v") protected String value; } And i have inserted on Report and 4 Properties for that report. Now when i execute this: this.findByCriteria( Order.asc("created"), Restrictions.eq("user", user.getObject(UserField.ID)) ) ); I get back the report 4 times, instead of just the once with a Map with the 4 properties in. I'm not great at Hibernate to be honest, prefer straight SQL but I must learn, but i can't see what it is that is wrong.....? Any suggestions?

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  • Tail recursion and memoization with C#

    - by Jay
    I'm writing a function that finds the full path of a directory based on a database table of entries. Each record contains a key, the directory's name, and the key of the parent directory (it's the Directory table in an MSI if you're familiar). I had an iterative solution, but it started looking a little nasty. I thought I could write an elegant tail recursive solution, but I'm not sure anymore. I'll show you my code and then explain the issues I'm facing. Dictionary<string, string> m_directoryKeyToFullPathDictionary = new Dictionary<string, string>(); ... private string ExpandDirectoryKey(Database database, string directoryKey) { // check for terminating condition string fullPath; if (m_directoryKeyToFullPathDictionary.TryGetValue(directoryKey, out fullPath)) { return fullPath; } // inductive step Record record = ExecuteQuery(database, "SELECT DefaultDir, Directory_Parent FROM Directory where Directory.Directory='{0}'", directoryKey); // null check string directoryName = record.GetString("DefaultDir"); string parentDirectoryKey = record.GetString("Directory_Parent"); return Path.Combine(ExpandDirectoryKey(database, parentDirectoryKey), directoryName); } This is how the code looked when I realized I had a problem (with some minor validation/massaging removed). I want to use memoization to short circuit whenever possible, but that requires me to make a function call to the dictionary to store the output of the recursive ExpandDirectoryKey call. I realize that I also have a Path.Combine call there, but I think that can be circumvented with a ... + Path.DirectorySeparatorChar + .... I thought about using a helper method that would memoize the directory and return the value so that I could call it like this at the end of the function above: return MemoizeHelper( m_directoryKeyToFullPathDictionary, Path.Combine(ExpandDirectoryKey(database, parentDirectoryKey)), directoryName); But I feel like that's cheating and not going to be optimized as tail recursion. Any ideas? Should I be using a completely different strategy? This doesn't need to be a super efficient algorithm at all, I'm just really curious. I'm using .NET 4.0, btw. Thanks!

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  • What is a NULL value

    - by Adi
    I am wondering , what exactly is stored in the memory when we say a particular variable pointer to be NULL. suppose I have a structure, say typdef struct MEM_LIST MEM_INSTANCE; struct MEM_LIST { char *start_addr; int size; MEM_INSTANCE *next; }; MEM_INSTANCE *front; front = (MEM_INSTANCE*)malloc(sizeof(MEM_INSTANCE*)); -1) If I make front=NULL. What will be the value which actually gets stored in the different fields of the front, say front-size ,front-start_addr. Is it 0 or something else. I have limited knowledge in this NULL thing. -2) If I do a free(front); It frees the memory which is pointed out by front. So what exactly free means here, does it make it NULL or make it all 0. -3) What can be a good strategy to deal with initialization of pointers and freeing them . Thanks in advance

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  • File based caching under PHP

    - by azatoth
    I've been using http://code.google.com/p/phpbrowscap/ for a project, and it usually works nice. But a few times it's cache, which is plain php-files (see http://code.google.com/p/phpbrowscap/source/browse/trunk/browscap/Browscap.php#372 et. al.), has been "zeroed", i.e. the whole cache file has become large blob of NULLs. Instead of trying to find out why the files become NULL, I though perhaps it might be better to change the caching strategy to something more resilient. So I do wonder if you has any good ideas what would be a good solution; I've been looking at http://www.jongales.com/blog/2009/02/18/simple-file-based-php-cache-class/ and http://www.phpclasses.org/package/313-PHP-Cache-arbitrary-data-in-files-.html and I also though of just saving an serialized array to the file instead of pure php as it's been doing now; But I'm uncertain what approach I should target here. I'm grateful for any insight into this area of technology, as I know it's complex from a performance point of view.

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  • Handling selection and deselection of objects in a user interface

    - by Dennis
    I'm writing a small audio application (in Silverlight, but that's not really relevant I suppose), and I'm a struggling with a problem I've faced before and never solved properly. This time I want to get it right. In the application there is one Arrangement control, which contains several Track controls, and every Track can contain AudioObject controls (these are all custom user controls). The user needs to be able to select audio objects, and when these objects are selected they are rendered differently. I can make this happen by hooking into the MouseDown event of the AudioObject control and setting state accordingly. So far so good, but when an audio object is selected, all other audio objects need to be deselected (well, unless the user holds the shift key). Audio objects don't know about other audio objects though, so they have no way to tell the rest to deselect themselves. Now if I would approach this problem like I did the last time I would pass a reference to the Arrangement control in the constructor of the AudioObject control and give the Arrangement control a DeselectAll() method or something like that, which would tell all Track controls to deselect all their AudioObject controls. This feels wrong, and if I apply this strategy to similar issues I'm afraid I will soon end up with every object having a reference to every other object, creating one big tightly coupled mess. It feels like opening the floodgates for poorly designed code. Is there a better way to handle this?

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  • @PrePersist with entity inheritance

    - by gerry
    I'm having some problems with inheritance and the @PrePersist annotation. My source code looks like the following: _the 'base' class with the annotated updateDates() method: @javax.persistence.Entity @Inheritance(strategy = InheritanceType.TABLE_PER_CLASS) public class Base implements Serializable{ ... @Id @GeneratedValue protected Long id; ... @Column(nullable=false) @Temporal(TemporalType.TIMESTAMP) private Date creationDate; @Column(nullable=false) @Temporal(TemporalType.TIMESTAMP) private Date lastModificationDate; ... public Date getCreationDate() { return creationDate; } public void setCreationDate(Date creationDate) { this.creationDate = creationDate; } public Date getLastModificationDate() { return lastModificationDate; } public void setLastModificationDate(Date lastModificationDate) { this.lastModificationDate = lastModificationDate; } ... @PrePersist protected void updateDates() { if (creationDate == null) { creationDate = new Date(); } lastModificationDate = new Date(); } } _ now the 'Child' class that should inherit all methods "and annotations" from the base class: @javax.persistence.Entity @NamedQueries({ @NamedQuery(name=Sensor.QUERY_FIND_ALL, query="SELECT s FROM Sensor s") }) public class Sensor extends Entity { ... // additional attributes @Column(nullable=false) protected String value; ... // additional getters, setters ... } If I store/persist instances of the Base class to the database, everything works fine. The dates are getting updated. But now, if I want to persist a child instance, the database throws the following exception: MySQLIntegrityConstraintViolationException: Column 'CREATIONDATE' cannot be null So, in my opinion, this is caused because in Child the method "@PrePersist protected void updateDates()" is not called/invoked before persisting the instances to the database. What is wrong with my code?

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  • Advice Please: SQL Server Identity vs Unique Identifier keys when using Entity Framework

    - by c.batt
    I'm in the process of designing a fairly complex system. One of our primary concerns is supporting SQL Server peer-to-peer replication. The idea is to support several geographically separated nodes. A secondary concern has been using a modern ORM in the middle tier. Our first choice has always been Entity Framework, mainly because the developers like to work with it. (They love the LiNQ support.) So here's the problem: With peer-to-peer replication in mind, I settled on using uniqueidentifier with a default value of newsequentialid() for the primary key of every table. This seemed to provide a good balance between avoiding key collisions and reducing index fragmentation. However, it turns out that the current version of Entity Framework has a very strange limitation: if an entity's key column is a uniqueidentifier (GUID) then it cannot be configured to use the default value (newsequentialid()) provided by the database. The application layer must generate the GUID and populate the key value. So here's the debate: abandon Entity Framework and use another ORM: use NHibernate and give up LiNQ support use linq2sql and give up future support (not to mention get bound to SQL Server on DB) abandon GUIDs and go with another PK strategy devise a method to generate sequential GUIDs (COMBs?) at the application layer I'm leaning towards option 1 with linq2sql (my developers really like linq2[stuff]) and 3. That's mainly because I'm somewhat ignorant of alternate key strategies that support the replication scheme we're aiming for while also keeping things sane from a developer's perspective. Any insight or opinion would be greatly appreciated.

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  • Hibernate: Querying objects by attributes of inherited classes

    - by MichaelD
    Hi all, I ran into a problem with Hibernate concerning queries on classes which use inheritance. Basically I've the following class hierarchy: @Entity @Table( name = "recording" ) class Recording { ClassA attributeSet; ... } @Entity @Inheritance( strategy = InheritanceType.JOINED ) @Table( name = "classA" ) public class ClassA { String Id; ... } @Entity @Table( name = "ClassB1" ) @PrimaryKeyJoinColumn( name = "Id" ) public class ClassB1 extends ClassA { private Double P1300; private Double P2000; } @Entity @Table( name = "ClassB2" ) @PrimaryKeyJoinColumn( name = "Id" ) public class ClassB2 extends ClassA { private Double P1300; private Double P3000; } The hierarchy is already given like this and I cannot change it easily. As you can see ClassB1 and ClassB2 inherit from ClassA. Both classes contain a set of attributes which sometimes even have the same names (but I can't move them to ClassA since there are possible more sub-classes which do not use them). The Recording class references one instance of one of this classes. Now my question: What I want to do is selecting all Recording objects in my database which refer to an instance of either ClassB1 or ClassB2 with e.g. the field P1300 == 15.5 (so this could be ClassB1 or ClassB2 instances since the P1300 attribute is declared in both classes). What I tried is something like this: Criteria criteria = session.createCriteria(Recording.class); criteria.add( Restrictions.eq( "attributeSet.P1300", new Double(15.5) ) ); criteria.list(); But since P1300 is not an attribute of ClassA hibernate throws an exception telling me: could not resolve property: P1300 of: ClassA How can I tell hibernate that it should search in all subclasses to find the attribute I want to filter? Thanks MichaelD

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  • Parsing HTTP - Bytes.length != String.length

    - by hotzen
    Hello, I consume HTTP via nio.SocketChannel, so I get chunks of data as Array[Byte]. I want to put these chunks into a parser and continue parsing after each chunk has been put. HTTP itself seems to use an ISO8859-Charset but the Payload/Body itself may be arbitrarily encoded: If the HTTP Content-Length specifies X bytes, the UTF8-decoded Body may have much less Characters (1 Character may be represented in UTF8 by 2 bytes, etc). So what is a good parsing strategy to honor an explicitly specified Content-Length and/or a Transfer-Encoding: Chunked which specifies a chunk-length to be honored. append each data-chunk to an mutable.ArrayBuffer[Byte], search for CRLF in the bytes, decode everything from 0 until CRLF to String and match with Regular-Expressions like StatusRegex, HeaderRegex, etc? decode each data-chunk with the proper charset (e.g. iso8859, utf8, etc) and add to StringBuilder. With this solution I am not able to honor any Content-Length or Chunk-Size, but.. do I have to care for it? any other solution... ?

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  • Is there such a thing as IMAP for podcasts?

    - by Gerrit
    Is there such a thing as IMAP for podcasts? I own a desktop, laptop, iPod, smartphone and a web-client all downloading StackOverflow Podcasts. (among others) They all tell me which episodes are available and which are already played. Everything is a horrible mess, ofcourse. My iPod is somewhat in sync with my desktop, but everything else is a random jungle. The same problem with e-mail is solved by IMAP. Every device gets content and meta-information from one server, and stays in sync with it. Per device, I can set preferences (do or do not download the complete archive including junkmail). Can we implement the IMAP approach for podcasts? Or is there a better metaphore/standard to solve this problem? How will the adoption-strategy look like? (by the way: except for the Windows smartphone, I own a full Apple-stack of products. Even then, I run into this problem) UPDATE The RSS-to-Imap link to sourceforge looks promesting, but very alpha/experimental. UPDATE 2 The one thing RSS is missing is the command/method/parameter/attribute to delete/unread items. RSS can only add, not remove. If RSS(N+1) (3?) could add a value for unread="true|false", it would be solved. If I cache all my RSS-feeds on my own server, and add the attribute myself, I only would have to convince iTunes and every other client to respect that.

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