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  • Copywriting For SEO - Should You Outsource?

    Copywriting for SEO is an often overlooked part of web design projects. This occurs for various reasons; time constraints, undervaluing of it's importance, a lack of understanding of what to look for when copywriting for SEO, budget constraints and much more.

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  • Duck checker in Python: does one exist?

    - by elliot42
    Python uses duck-typing, rather than static type checking. But many of the same concerns ultimately apply: does an object have the desired methods and attributes? Do those attributes have valid, in-range values? Whether you're writing constraints in code, or writing test cases, or validating user input, or just debugging, inevitably somewhere you'll need to verify that an object is still in a proper state--that it still "looks like a duck" and "quacks like a duck." In statically typed languages you can simply declare "int x", and anytime you create or mutate x, it will always be a valid int. It seems feasible to decorate a Python object to ensure that it is valid under certain constraints, and that every time that object is mutated it is still valid under those constraints. Ideally there would be a simple declarative syntax to express "hasattr length and length is non-negative" (not in those words. Not unlike Rails validators, but less human-language and more programming-language). You could think of this as ad-hoc interface/type system, or you could think of it as an ever-present object-level unit test. Does such a library exist to declare and validate constraint/duck-checking on Python-objects? Is this an unreasonable tool to want? :) (Thanks!) Contrived example: rectangle = {'length': 5, 'width': 10} # We live in a fictional universe where multiplication is super expensive. # Therefore any time we multiply, we need to cache the results. def area(rect): if 'area' in rect: return rect['area'] rect['area'] = rect['length'] * rect['width'] return rect['area'] print area(rectangle) rectangle['length'] = 15 print area(rectangle) # compare expected vs. actual output! # imagine the same thing with object attributes rather than dictionary keys.

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  • What the Hekaton?

    - by Tony Davis
    Hekaton, the power behind SQL Server 2014′s In-Memory OLTP technology, is intended to make data operations run orders of magnitude faster on SQL Server. This works its magic partly by serving database workloads entirely from main memory, using memory-optimized table structures. It replaces the relational engine’s standard locking model with an optimistic concurrency model based on time-stamped row versions. Deeper down the Hekaton engine uses new, ‘latch free’ data structures. So far, so good, but performance improvements on this scale require a compromise, and the compromise is that these aren’t tables as we understand them. For the database developer, these differences are painful because they involve sacrificing some very important bits of the relational model. Most importantly, Hekaton tables don’t currently support FOREIGN KEY constraints or CHECK constraints, and you can’t put the checks in triggers because there aren’t any DML triggers either. Constraints allow a relational designer to enforce relational integrity and data integrity. Without them, of course, ‘bad data’ can get into our Hekaton tables. There is no easy way of preventing it. For several classes of database and data, this is a show-stopper. One may regard all these restrictions regretfully, seeing limited opportunity to try out Hekaton with current databases, but perhaps there is also a sudden glow of recognition. Isn’t this how we all originally imagined table variables were going to be, back in SQL 2005? And they have much the same restrictions. Maybe, instead of pretending that a currently-designed database can be ‘Hekatonized’ with a few mouse clicks, we should redesign databases for SQL 2014 to replace table variables with Hekaton tables, exploiting this technology for fast intermediate processing, and for the most part forget, for now, the idea of trying to convert our base relational tables into Hekaton tables. Few database developers would be averse to having their working tables running an order of magnitude faster, as long as it didn’t compromise the integrity of the data in the base tables.

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  • MySQL Cluster 7.3: On-Demand Webinar and Q&A Available

    - by Mat Keep
    The on-demand webinar for the MySQL Cluster 7.3 Development Release is now available. You can learn more about the design, implementation and getting started with all of the new MySQL Cluster 7.3 features from the comfort and convenience of your own device, including: - Foreign Key constraints in MySQL Cluster - Node.js NoSQL API  - Auto-installation of higher performance distributed, clusters We received some great questions over the course of the webinar, and I wanted to share those for the benefit of a broader audience. Q. What Foreign Key actions are supported: A. The core referential actions defined in the SQL:2003 standard are implemented: CASCADE RESTRICT NO ACTION SET NULL Q. Where are Foreign Keys implemented, ie data nodes or SQL nodes? A. They are implemented in the data nodes, therefore can be enforced for both the SQL and NoSQL APIs Q. Are they compatible with the InnoDB Foreign Key implementation? A. Yes, with the following exceptions: - InnoDB doesn’t support “No Action” constraints, MySQL Cluster does - You can choose to suspend FK constraint enforcement with InnoDB using the FOREIGN_KEY_CHECKS parameter; at the moment, MySQL Cluster ignores that parameter. - You cannot set up FKs between 2 tables where one is stored using MySQL Cluster and the other InnoDB. - You cannot change primary keys through the NDB API which means that the MySQL Server actually has to simulate such operations by deleting and re-adding the row. If the PK in the parent table has a FK constraint on it then this causes non-ideal behaviour. With Restrict or No Action constraints, the change will result in an error. With Cascaded constraints, you’d want the rows in the child table to be updated with the new FK value but, the implicit delete of the row from the parent table would remove the associated rows from the child table and the subsequent implicit insert into the parent wouldn’t reinstate the child rows. For this reason, an attempt to add an ON UPDATE CASCADE where the parent column is a primary key will be rejected. Q. Does adding or dropping Foreign Keys cause downtime due to a schema change? A. Nope, this is an online operation. MySQL Cluster supports a number of on-line schema changes, ie adding and dropping indexes, adding columns, etc. Q. Where can I see an example of node.js with MySQL Cluster? A. Check out the tutorial and download the code from GitHub Q. Can I use the auto-installer to support remote deployments? How about setting up MySQL Cluster 7.2? A. Yes to both! Q. Can I get a demo Check out the tutorial. You can download the code from http://labs.mysql.com/ Go to Select Build drop-down box Q. What is be minimum internet speen required for Geo distributed cluster with synchronous replication? A. if you're splitting you cluster between sites then we recommend a network latency of 20ms or less. Alternatively, use MySQL asynchronous replication where the latency of your WAN doesn't impact the latency of your reads/writes. Q. Where you can one learn more about the PayPal project with MySQL Cluster? A. Take a look at the following - you'll find press coverage, a video and slides from their keynote presentation  So, if you want to learn more, listen to the new MySQL Cluster 7.3 on-demand webinar  MySQL Cluster 7.3 is still in the development phase, so it would be great to get your feedback on these new features, and things you want to see!

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  • T-SQL Tuesday #025 &ndash; CHECK Constraint Tricks

    - by Most Valuable Yak (Rob Volk)
    Allen White (blog | twitter), marathoner, SQL Server MVP and presenter, and all-around awesome author is hosting this month's T-SQL Tuesday on sharing SQL Server Tips and Tricks.  And for those of you who have attended my Revenge: The SQL presentation, you know that I have 1 or 2 of them.  You'll also know that I don't recommend using anything I talk about in a production system, and will continue that advice here…although you might be sorely tempted.  Suffice it to say I'm not using these examples myself, but I think they're worth sharing anyway. Some of you have seen or read about SQL Server constraints and have applied them to your table designs…unless you're a vendor ;)…and may even use CHECK constraints to limit numeric values, or length of strings, allowable characters and such.  CHECK constraints can, however, do more than that, and can even provide enhanced security and other restrictions. One tip or trick that I didn't cover very well in the presentation is using constraints to do unusual things; specifically, limiting or preventing inserts into tables.  The idea was to use a CHECK constraint in a way that didn't depend on the actual data: -- create a table that cannot accept data CREATE TABLE dbo.JustTryIt(a BIT NOT NULL PRIMARY KEY, CONSTRAINT chk_no_insert CHECK (GETDATE()=GETDATE()+1)) INSERT dbo.JustTryIt VALUES(1)   I'll let you run that yourself, but I'm sure you'll see that this is a pretty stupid table to have, since the CHECK condition will always be false, and therefore will prevent any data from ever being inserted.  I can't remember why I used this example but it was for some vague and esoteric purpose that applies to about, maybe, zero people.  I come up with a lot of examples like that. However, if you realize that these CHECKs are not limited to column references, and if you explore the SQL Server function list, you could come up with a few that might be useful.  I'll let the names describe what they do instead of explaining them all: CREATE TABLE NoSA(a int not null, CONSTRAINT CHK_No_sa CHECK (SUSER_SNAME()<>'sa')) CREATE TABLE NoSysAdmin(a int not null, CONSTRAINT CHK_No_sysadmin CHECK (IS_SRVROLEMEMBER('sysadmin')=0)) CREATE TABLE NoAdHoc(a int not null, CONSTRAINT CHK_No_AdHoc CHECK (OBJECT_NAME(@@PROCID) IS NOT NULL)) CREATE TABLE NoAdHoc2(a int not null, CONSTRAINT CHK_No_AdHoc2 CHECK (@@NESTLEVEL>0)) CREATE TABLE NoCursors(a int not null, CONSTRAINT CHK_No_Cursors CHECK (@@CURSOR_ROWS=0)) CREATE TABLE ANSI_PADDING_ON(a int not null, CONSTRAINT CHK_ANSI_PADDING_ON CHECK (@@OPTIONS & 16=16)) CREATE TABLE TimeOfDay(a int not null, CONSTRAINT CHK_TimeOfDay CHECK (DATEPART(hour,GETDATE()) BETWEEN 0 AND 1)) GO -- log in as sa or a sysadmin server role member, and try this: INSERT NoSA VALUES(1) INSERT NoSysAdmin VALUES(1) -- note the difference when using sa vs. non-sa -- then try it again with a non-sysadmin login -- see if this works: INSERT NoAdHoc VALUES(1) INSERT NoAdHoc2 VALUES(1) GO -- then try this: CREATE PROCEDURE NotAdHoc @val1 int, @val2 int AS SET NOCOUNT ON; INSERT NoAdHoc VALUES(@val1) INSERT NoAdHoc2 VALUES(@val2) GO EXEC NotAdHoc 2,2 -- which values got inserted? SELECT * FROM NoAdHoc SELECT * FROM NoAdHoc2   -- and this one just makes me happy :) INSERT NoCursors VALUES(1) DECLARE curs CURSOR FOR SELECT 1 OPEN curs INSERT NoCursors VALUES(2) CLOSE curs DEALLOCATE curs INSERT NoCursors VALUES(3) SELECT * FROM NoCursors   I'll leave the ANSI_PADDING_ON and TimeOfDay tables for you to test on your own, I think you get the idea.  (Also take a look at the NoCursors example, notice anything interesting?)  The real eye-opener, for me anyway, is the ability to limit bad coding practices like cursors, ad-hoc SQL, and sa use/abuse by using declarative SQL objects.  I'm sure you can see how and why this would come up when discussing Revenge: The SQL.;) And the best part IMHO is that these work on pretty much any version of SQL Server, without needing Policy Based Management, DDL/login triggers, or similar tools to enforce best practices. All seriousness aside, I highly recommend that you spend some time letting your mind go wild with the possibilities and see how far you can take things.  There are no rules! (Hmmmm, what can I do with rules?) #TSQL2sDay

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  • Grails - Language prefix in url mappings

    - by Art79
    Hi there im having problem with language mappings. The way i want it to work is that language is encoded in the url like /appname/de/mycontroller/whatever If you go to /appname/mycontroller/action it should check your session and if there is no session pick language based on browser preference and redirect to the language prefixed site. If you have session then it will display english. English does not have en prefix (to make it harder). So i created mappings like this: class UrlMappings { static mappings = { "/$lang/$controller/$action?/$id?"{ constraints { lang(matches:/pl|en/) } } "/$lang/store/$category" { controller = "storeItem" action = "index" constraints { lang(matches:/pl|en/) } } "/$lang/store" { controller = "storeItem" action = "index" constraints { lang(matches:/pl|en/) } } "/$controller/$action?/$id?"{ lang="en" constraints { } } "/store/$category" { lang="en" controller = "storeItem" action = "index" } "/store" { lang="en" controller = "storeItem" action = "index" } "/"(view:"/index") "500"(view:'/error') } } Its not fully working and langs are hardcoded just for now. I think i did something wrong. Some of the reverse mappings work but some dont add language. If i use link tag and pass params:[lang:'pl'] then it works but if i add params:[lang:'pl', page:2] then it does not. In the second case both lang and page number become parameters in the query string. What is worse they dont affect the locale so page shows in english. Can anyone please point me to the documentation what are the rules of reverse mappings or even better how to implement such language prefix in a good way ? THANKS

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  • Moving from a non-clustered PK to a clustered PK in SQL 2005

    - by adaptr
    HI all, I recently asked this question in another thread, and thought I would reproduce it here with my solution: What if I have an auto-increment INT as my non-clustered primary key, and there are about 15 foreign keys defined to it ? (snide comment about original designer being braindead in the original :) ) This is a 15M row table, on a live database, SQL Standard, so dropping indexes is out of the question. Even temporarily dropping the foreign key constraints will be difficult. I'm curious if anybody has a solution that causes minimal downtime. I tested this in our testing environment and finally found that the downtime wasn't as severe as I had originally feared. I ended up writing a script that drops all FK constraints, then drops the non-clustered key, re-creates the PK as a clustered index, and finally re-created all FKs WITH NOCHECK to avoid trawling through all FKs to check constraint compliance. Then I just enable the CHECK constraints to enable constraint checking from that point onwards, and all is dandy :) The most important thing to realize is that during the time the FKs are absent, there MUST NOT be any INSERTs or DELETEs on the parent table, as this may break the constraints and cause issues in the future. The total time taken for clustering a 15M row, 800MB index was ~4 minutes :)

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  • Diagnosing and debugging LAN congestion / connection issues

    - by John Weldon
    What are the top N tools / methodologies used to diagnose and repair network issues? Given a LAN, for example, where users are able to consistently ping an outside server, but any data intensive connections are flaky; how would you begin solving the network issues? I imagine issues like congestion, bandwidth constraints, throughput constraints, etc. are all factors, but I don't know how to diagnose those issues. I'm especially interested in LAN environments (rather than WAN)

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  • Grails: Querying Associations causes groovy.lang.MissingMethodException

    - by Paul
    Hi, I've got an issue with Grails where I have a test app with: class Artist { static constraints = { name() } static hasMany = [albums:Album] String name } class Album { static constraints = { name() } static hasMany = [ tracks : Track ] static belongsTo = [artist: Artist] String name } class Track { static constraints = { name() lyrics(nullable: true) } Lyrics lyrics static belongsTo = [album: Album] String name } The following query (and a more advanced, nested association query) works in the Grails Console but fails with a groovy.lang.MissingMethodException when running the app with 'run-app': def albumCriteria = tunehub.Album.createCriteria() def albumResults = albumCriteria.list { like("name", receivedAlbum) artist { like("name", receivedArtist) } // Fails here maxResults(1) } Stacktrace: groovy.lang.MissingMethodException: No signature of method: java.lang.String.call() is applicable for argument types: (tunehub.LyricsService$_getLyrics_closure1_closure2) values: [tunehub.LyricsService$_getLyrics_closure1_closure2@604106] Possible solutions: wait(), any(), wait(long), each(groovy.lang.Closure), any(groovy.lang.Closure), trim() at tunehub.LyricsService$_getLyrics_closure1.doCall(LyricsService.groovy:61) at tunehub.LyricsService$_getLyrics_closure1.doCall(LyricsService.groovy) (...truncated...) Any pointers?

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  • mocking command object in grails controller results in hasErrors() return false no matter what! Plea

    - by egervari
    I have a controller that uses a command object in a controller action. When mocking this command object in a grails' controller unit test, the hasErrors() method always returns false, even when I am purposefully violating its constraints. def save = { RegistrationForm form -> if(form.hasErrors()) { // code block never gets executed } else { // code block always gets executed } } In the test itself, I do this: mockCommandObject(RegistrationForm) def form = new RegistrationForm(emailAddress: "ken.bad@gmail", password: "secret", confirmPassword: "wrong") controller.save(form) I am purposefully giving it a bad email address, and I am making sure the password and the confirmPassword properties are different. In this case, hasErrors() should return true... but it doesn't. I don't know how my testing can be any where reliable if such a basic thing does not work :/ Here is the RegistrationForm class, so you can see the constraints I am using: class RegistrationForm { def springSecurityService String emailAddress String password String confirmPassword String getEncryptedPassword() { springSecurityService.encodePassword(password) } static constraints = { emailAddress(blank: false, email: true) password(blank: false, minSize:4, maxSize: 10) confirmPassword(blank: false, validator: { confirmPassword, form -> confirmPassword == form.password }) } }

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  • Which of the following relational database management systems would a company adopt (for migration), if any, MS Access, MS SQL Server or MySQL?

    - by Hassan Hagi
    Dear programmers, as part of my final year university project, I am conducting research into relational database management systems such as Microsoft Office Access 2007, Microsoft SQL Server 2008 and MySQL 5.1. The description does not need to be detailed however; I am trying to find empirical evidence and professional opinion/fact to determine which of the three databases are best suited for the required size of company (stated or unstated). OS: Microsoft windows (XP or newer) Please consider the following, but full details are not necessary: Memory management Migration Design constraints Integrity (data and others) Triggers User constraints Ease of use Performance Crash Recovery (not the operating system) Total Cost of Ownership (TCO) Also any info on Open source (to do with the three RDBMS) Thank you for your time and help. Hassan Hagi

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  • Oracle GoldenGate: Knowledge Document Series Post #1

    - by Doug Reid
    0 false 18 pt 18 pt 0 0 false false false /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin;} Over the course of the next several weeks, the Oracle GoldenGate team will be posting highlights from the knowledge base on My Oracle Support. The intent is to bring greater awareness to our user community of some fantastic best practices documents that are available to anyone with a valid CSI.   These documents were originally created for our internal teams, but the content was so good and useful that we have made them available externally for our user community.  The first in our series is the Oracle GoldenGate database Schema Profile check script (Doc ID 1296168.1). “This script is intended to query the database by schema to identify current configuration and identify any unsupported data types or types that may need special considerations for Oracle GoldenGate in an Oracle environment. This is the Oracle database profile script.  Added check for deferred constraints. Deferred constraints may cause ADD TRANDATA to select the wrong column for logging. Use KEYCOLS for tables with deferred constraints.” Click here to view the document  Check back weekly for additional new postings.

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  • How to handle updated configuration when it's already been cloned for editing

    - by alexrussell
    Really sorry about the title that probably doesn't make much sense. Hopefully I can explain myself better here as it's something that's kinda bugged me for ages, and is now becoming a pressing concern as I write a bit of software with configuration. Most software comes with default configuration options stored in the app itself, and then there's a configuration file (let's say) that a user can edit. Once created/edited for the first time, subsequent updates to the application can not (easily) modify this configuration file for fear of clobbering the user's own changes to the default configuration. So my question is, if my application adds a new configurable parameter, what's the best way to aid discoverability of the setting and allow the user (developer) to override it as nicely as possible given the following constraints: I actually don't have a canonical default config in the application per se, it's more of a 'cascading filesystem'-like affair - the config template is stored in default/config.json and when the user wishes to edit the configuration, it's copied to user/config.json. If a user config is found it is used - there is no automatic overriding of a subset of keys, the whole new file is used and that's that. If there's no user config the default config is used. When a user wishes to edit the config they run a command to 'generate' it for them (which simply copies the config.json file from the default to the user directory). There is no UI for the configuration options as it's not appropriate to the userbase (think of my software as a library or something, the users are developers, the config is done in the user/config.json file). Due to my software being library-like there's no simple way to, on updating of the software, run some tasks automatically (so any ideas of look at the current config, compare to template config, add ing missing keys) aren't appropriate. The only solution I can think of right now is to say "there's a new config setting X" in release notes, but this doesn't seem ideal to me. If you want any more information let me know. The above specifics are not actually 100% true to my situation, but they represent the problem equally well with lower complexity. If you do want specifics, however, I can explain the exact setup. Further clarification of the type of configuration I mean: think of the Atom code editor. There appears to be a default 'template' config file somewhere, but as soon as a configuration option is edited ~/.atom/config.cson is generated and the setting goes in there. From now on is Atom is updated and gets a new configuration key, this file cannot be overwritten by Atom without a lot of effort to ensure that the addition/modification of the key does not clobber. In Atom's case, because there is a GUI for editing settings, they can get away with just adding the UI for the new setting into the UI to aid 'discoverability' of the new setting. I don't have that luxury. Clarification of my constraints and what I'm actually looking for: The software I'm writing is actually a package for a larger system. This larger system is what provides the configuration, and the way it works is kinda fixed - I just do a config('some.key') kinda call and it knows to look to see if the user has a config clone and if so use it, otherwise use the default config which is part of my package. Now, while I could make my application edit the user's configuration files (there is a convention about where they're stored), it's generally not done, so I'd like to live with the constraints of the system I'm using if possible. And it's not just about discoverability either, one large concern is that the addition of a configuration key won't actually work as soon as the user has their own copy of the original template. Adding the key to the template won't make a difference as that file is never read. As such, I think this is actually quite a big flaw in the design of the configuration cascading system and thus needs to be taken up with my upstream. So, thinking about it, based on my constraints, I don't think there's going to be a good solution save for either editing the user's configuration or using a new config file every time there are updates to the default configuration. Even the release notes idea from above isn't doable as, if the user does not follow the advice, suddenly I have a config key with no value (user-defined or default). So the new question is this: what is the general way to solve the problem of having a default configuration in template config files and allowing a user to make user-specific version of these in order to override the defaults? A per-key cascade (rather than per-file cascade) where the user only specifies their overrides? In this case, what happens if a configuration value is an array - do we replace or append to the default (or, more realistically, how does the user specify whether they wish to replace or append to)? It seems like configuration is kinda hard, so how is it solved in the wild?

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  • Are there any examples of a temporal field/object updater?

    - by Bryan Agee
    The system in question has numerous examples of temporal objects and fields--ones which are a certain variable at a certain point in time. An example of this would be someone's rate of pay--there are different answers depending on when you ask and what the constraints might be; eg, can there ever be more than one of a certain temporal object concurrently, etc. Ideally, there would be an object that handles those constraints when a new state/stateful object is introduced; when a new value is set, it would prevent creating negative ranges and overlaps. Martin Fowler has written some great material on this (such as this description of Temporal Objects) , but what I've found of it tends to be entirely theoretic, with no concrete implementations. PHP is the target language, but examples in any language would be most helpful.

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  • Is ROA a specific form of doing SOA?

    - by JohnDoDo
    I have read somewhere that ROA (Resource Oriented Architecture) is SOA (Service Oriented Architecture) with specific constraints added. SOA is the abstract concept of combining discrete pieces of software and ROA is an implementation of SOA with all of the constraints of RESTful services applied to it: SOA = the concept ROA = the concept + specific implementation details I also had my share of posts saying that ROA is different than SOA, then simply fallback to statements like "ROA is REST" and "SOA is SOAP" and presenting the same more or less pertinent comparisons and differences between SOAP and REST. So just to clear up my confusion: Is ROA a specific form of doing SOA?

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  • Is it feasible and useful to auto-generate some code of unit tests?

    - by skiwi
    Earlier today I have come up with an idea, based upon a particular real use case, which I would want to have checked for feasability and usefulness. This question will feature a fair chunk of Java code, but can be applied to all languages running inside a VM, and maybe even outside. While there is real code, it uses nothing language-specific, so please read it mostly as pseudo code. The idea Make unit testing less cumbersome by adding in some ways to autogenerate code based on human interaction with the codebase. I understand this goes against the principle of TDD, but I don't think anyone ever proved that doing TDD is better over first creating code and then immediatly therafter the tests. This may even be adapted to be fit into TDD, but that is not my current goal. To show how it is intended to be used, I'll copy one of my classes here, for which I need to make unit tests. public class PutMonsterOnFieldAction implements PlayerAction { private final int handCardIndex; private final int fieldMonsterIndex; public PutMonsterOnFieldAction(final int handCardIndex, final int fieldMonsterIndex) { this.handCardIndex = Arguments.requirePositiveOrZero(handCardIndex, "handCardIndex"); this.fieldMonsterIndex = Arguments.requirePositiveOrZero(fieldMonsterIndex, "fieldCardIndex"); } @Override public boolean isActionAllowed(final Player player) { Objects.requireNonNull(player, "player"); Hand hand = player.getHand(); Field field = player.getField(); if (handCardIndex >= hand.getCapacity()) { return false; } if (fieldMonsterIndex >= field.getMonsterCapacity()) { return false; } if (field.hasMonster(fieldMonsterIndex)) { return false; } if (!(hand.get(handCardIndex) instanceof MonsterCard)) { return false; } return true; } @Override public void performAction(final Player player) { Objects.requireNonNull(player); if (!isActionAllowed(player)) { throw new PlayerActionNotAllowedException(); } Hand hand = player.getHand(); Field field = player.getField(); field.setMonster(fieldMonsterIndex, (MonsterCard)hand.play(handCardIndex)); } } We can observe the need for the following tests: Constructor test with valid input Constructor test with invalid inputs isActionAllowed test with valid input isActionAllowed test with invalid inputs performAction test with valid input performAction test with invalid inputs My idea mainly focuses on the isActionAllowed test with invalid inputs. Writing these tests is not fun, you need to ensure a number of conditions and you check whether it really returns false, this can be extended to performAction, where an exception needs to be thrown in that case. The goal of my idea is to generate those tests, by indicating (through GUI of IDE hopefully) that you want to generate tests based on a specific branch. The implementation by example User clicks on "Generate code for branch if (handCardIndex >= hand.getCapacity())". Now the tool needs to find a case where that holds. (I haven't added the relevant code as that may clutter the post ultimately) To invalidate the branch, the tool needs to find a handCardIndex and hand.getCapacity() such that the condition >= holds. It needs to construct a Player with a Hand that has a capacity of at least 1. It notices that the capacity private int of Hand needs to be at least 1. It searches for ways to set it to 1. Fortunately it finds a constructor that takes the capacity as an argument. It uses 1 for this. Some more work needs to be done to succesfully construct a Player instance, involving the creation of objects that have constraints that can be seen by inspecting the source code. It has found the hand with the least capacity possible and is able to construct it. Now to invalidate the test it will need to set handCardIndex = 1. It constructs the test and asserts it to be false (the returned value of the branch) What does the tool need to work? In order to function properly, it will need the ability to scan through all source code (including JDK code) to figure out all constraints. Optionally this could be done through the javadoc, but that is not always used to indicate all constraints. It could also do some trial and error, but it pretty much stops if you cannot attach source code to compiled classes. Then it needs some basic knowledge of what the primitive types are, including arrays. And it needs to be able to construct some form of "modification trees". The tool knows that it needs to change a certain variable to a different value in order to get the correct testcase. Hence it will need to list all possible ways to change it, without using reflection obviously. What this tool will not replace is the need to create tailored unit tests that tests all kinds of conditions when a certain method actually works. It is purely to be used to test methods when they invalidate constraints. My questions: Is creating such a tool feasible? Would it ever work, or are there some obvious problems? Would such a tool be useful? Is it even useful to automatically generate these testcases at all? Could it be extended to do even more useful things? Does, by chance, such a project already exist and would I be reinventing the wheel? If not proven useful, but still possible to make such thing, I will still consider it for fun. If it's considered useful, then I might make an open source project for it depending on the time. For people searching more background information about the used Player and Hand classes in my example, please refer to this repository. At the time of writing the PutMonsterOnFieldAction has not been uploaded to the repo yet, but this will be done once I'm done with the unit tests.

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  • Contiguous Time Periods

    It is always more efficient to maintain referential integrity by using constraints rather than triggers. Sometimes it isn't obvious how to do this. Until a recent idea by Alex Kuznetsov, the history table presented problems for checking data that were difficult to solve with constraints. Joe Celko explains. Free trial of SQL Backup™“SQL Backup was able to cut down my backup time significantly AND achieved a 90% compression at the same time!” Joe Cheng. Download a free trial now.

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  • Is there any complications or side effects for changing final field access/visibility modifier from private to protected?

    - by Software Engeneering Learner
    I have a private final field in one class and then I want to address that field in a subclass. I want to change field access/visibility modifier from private to protected, so I don't have to call getField() method from subclass and I can instead address that field directly (which is more clear and cohessive). Will there be any side effects or complications if I change private to protected for a final field? UPDATE: from logical point of view, it's obvious that descendant should be able to directly access all predecessor fields, right? But there are certain constraints that are imposed on private final fields by JVM, like 100% initialization guarantee after construction phase(useful for concurrency) and so on. So I would like to know, by changing from private to protected, won't that or any other constraints be compromised?

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  • Advice on how to build html5 basic tile game (multi player, cross device)

    - by Eric
    I just read http://buildnewgames.com/real-time-multiplayer/ which explains the fundamentals and bets practices to build a massive real time multiplayer html5 game. My question is however given the “simplicity” of the game I need to build (simple kind of scratch game where you find or not something behind a tile), do I really need complex tools (canvas or node.js for example) ? The game The gamestakes place with a picture of our office as a background (tilemap). For HR purpose, we wish to create the following game fore employees: each day they can come to the website and click on a certain number of tiles (3 max per day) and find behind it motivation advice and interesting facts about the company. The constraints and rules the screen is divided into isometric 2D square tiles. There are basically an image (photograph of our office) number of tiles on the screen game: about 10,000 to much more (with scroll , see below) the players can scroll in 4 directions there are only 2 types of tiles: already open and closed player can open tiles that have not been yet open by other players there is no path for players : any player can click on any tile on the screen at any moment (if it’s not already done by another player) 2 players can’t be on the same tile at the same moment (or if they can, I’ll have to manage to see which one clicked on it first) only one type of player (all with similar roles), no weapon, no internal score… very simple game. no complex physics (collision only occurs if 2 players are on the same tile) The target I need to achieve: cross device, cross browsers high performance reaction (subsecond reactions) average nb of players per hour: up to 10K players per hour (quite high indeed but it’s because we aim at proving our case for the game to our business unit) So what I would like to know: 2D Tiled map: Do I need tiledmapeditor or can I enable me split the screen like here ? should I use canvas or plain html/css could be sufficient for my need? do I need a game engine/framework such as melon.js or crafty./js ? (even if the game play is extremely basic, I do need mouse and touché device support, mouse emulations on touch devices…) or ca I easily/quickly do it without? for my constraints and targets, should I use CPU acceleration ? for my constraints and targets, should I use web workers ? for the database, for a massively real time game should I avoid to put the current locations of player in MySQL as i feel it might slow me down. What kind of DB should I implement ? Thanks for your help !

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  • Is ROA a specific form of SOA?

    - by JohnDoDo
    I have read somewhere that ROA (Resource Oriented Architecture) is SOA (Service Oriented Architecture) with specific constraints added. SOA is the abstract term and that ROA is an implementation of SOA with all of the constraints of RESTful services (SOA = concept, ROA = concept + implementation details). I also had my share of posts saying that ROA is REST and that SOA is SOAP and going into the same more or less pertinent comparisons between the two (SOAP and REST that is) etc etc. So just to clear up my confusion: Is ROA a specific form of doing SOA?

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  • Problem creating a database with PHP PDO

    - by Leandro Alonso
    Hello guys, I'm having a problem with a SQL query in my PHP Application. When the user access it for the first time, the app executes this query to create all the database: CREATE TABLE `databases` ( `id` bigint(20) NOT NULL auto_increment, `driver` varchar(45) NOT NULL, `server` text NOT NULL, `user` text NOT NULL, `password` text NOT NULL, `database` varchar(200) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=2 ; -- -------------------------------------------------------- -- -- Table structure for table `modules` -- CREATE TABLE `modules` ( `id` bigint(20) unsigned NOT NULL auto_increment, `title` varchar(100) NOT NULL, `type` varchar(150) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=29 ; -- -------------------------------------------------------- -- -- Table structure for table `modules_data` -- CREATE TABLE `modules_data` ( `id` bigint(20) NOT NULL auto_increment, `module_id` bigint(20) unsigned NOT NULL, `key` varchar(150) NOT NULL, `value` tinytext, PRIMARY KEY (`id`), KEY `fk_modules_data_modules` (`module_id`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=184 ; -- -------------------------------------------------------- -- -- Table structure for table `modules_position` -- CREATE TABLE `modules_position` ( `user_id` bigint(20) unsigned NOT NULL, `tab_id` bigint(20) unsigned NOT NULL, `module_id` bigint(20) unsigned NOT NULL, `column` smallint(1) default NULL, `line` smallint(1) default NULL, PRIMARY KEY (`user_id`,`tab_id`,`module_id`), KEY `fk_modules_order_users` (`user_id`), KEY `fk_modules_order_tabs` (`tab_id`), KEY `fk_modules_order_modules` (`module_id`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; -- -------------------------------------------------------- -- -- Table structure for table `tabs` -- CREATE TABLE `tabs` ( `id` bigint(20) unsigned NOT NULL auto_increment, `title` varchar(60) NOT NULL, `columns` smallint(1) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=12 ; -- -------------------------------------------------------- -- -- Table structure for table `tabs_has_modules` -- CREATE TABLE `tabs_has_modules` ( `tab_id` bigint(20) unsigned NOT NULL, `module_id` bigint(20) unsigned NOT NULL, PRIMARY KEY (`tab_id`,`module_id`), KEY `fk_tabs_has_modules_tabs` (`tab_id`), KEY `fk_tabs_has_modules_modules` (`module_id`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; -- -------------------------------------------------------- -- -- Table structure for table `users` -- CREATE TABLE `users` ( `id` bigint(20) unsigned NOT NULL auto_increment, `login` varchar(60) NOT NULL, `password` varchar(64) NOT NULL, `email` varchar(100) NOT NULL, `name` varchar(250) default NULL, `user_level` bigint(20) unsigned NOT NULL, PRIMARY KEY (`id`), KEY `fk_users_user_levels` (`user_level`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=4 ; -- -------------------------------------------------------- -- -- Table structure for table `users_has_tabs` -- CREATE TABLE `users_has_tabs` ( `user_id` bigint(20) unsigned NOT NULL, `tab_id` bigint(20) unsigned NOT NULL, `order` smallint(2) NOT NULL, `columns_width` varchar(255) default NULL, PRIMARY KEY (`user_id`,`tab_id`), KEY `fk_users_has_tabs_users` (`user_id`), KEY `fk_users_has_tabs_tabs` (`tab_id`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; -- -------------------------------------------------------- -- -- Table structure for table `user_levels` -- CREATE TABLE `user_levels` ( `id` bigint(20) unsigned NOT NULL auto_increment, `level` smallint(2) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=3 ; -- -------------------------------------------------------- -- -- Table structure for table `user_meta` -- CREATE TABLE `user_meta` ( `id` bigint(20) unsigned NOT NULL auto_increment, `user_id` bigint(20) unsigned default NULL, `key` varchar(150) NOT NULL, `value` longtext NOT NULL, PRIMARY KEY (`id`), KEY `fk_user_meta_users` (`user_id`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=4 ; -- -- Constraints for dumped tables -- -- -- Constraints for table `modules_data` -- ALTER TABLE `modules_data` ADD CONSTRAINT `fk_modules_data_modules` FOREIGN KEY (`module_id`) REFERENCES `modules` (`id`) ON DELETE CASCADE ON UPDATE NO ACTION; -- -- Constraints for table `modules_position` -- ALTER TABLE `modules_position` ADD CONSTRAINT `fk_modules_order_modules` FOREIGN KEY (`module_id`) REFERENCES `modules` (`id`) ON DELETE CASCADE ON UPDATE NO ACTION, ADD CONSTRAINT `fk_modules_order_tabs` FOREIGN KEY (`tab_id`) REFERENCES `tabs` (`id`) ON DELETE CASCADE ON UPDATE NO ACTION, ADD CONSTRAINT `fk_modules_order_users` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE CASCADE ON UPDATE NO ACTION; -- -- Constraints for table `users` -- ALTER TABLE `users` ADD CONSTRAINT `fk_users_user_levels` FOREIGN KEY (`user_level`) REFERENCES `user_levels` (`id`) ON DELETE NO ACTION ON UPDATE NO ACTION; -- -- Constraints for table `user_meta` -- ALTER TABLE `user_meta` ADD CONSTRAINT `fk_user_meta_users` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE CASCADE ON UPDATE NO ACTION; INSERT INTO `user_levels` VALUES(1, 10); INSERT INTO `user_levels` VALUES(2, 1); INSERT INTO `users` VALUES(1, 'admin', 'password', '[email protected]', NULL, 1); INSERT INTO `user_meta` VALUES (NULL, 1, 'last_tab', 1); In some environments i get this error: SQLSTATE[HY000]: General error: 1005 Can't create table 'dms.databases' (errno: 150) I tried everything that I could find on Google but nothing works. The strange part is that if I run this query in PhpMyAdmin he creates my database, without any error.

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  • Implementing emailing (bulk & event based) features for my website.

    - by Kabeer
    Hello. For my upcoming social networking website, I am looking for suggestions on the best way to implement emailing. Here are some of my requirements and constraints: Requirements: - Should be able to send emails based on events (new registrations, change password, etc.), promotions (advertisements based on user consent), bulk mails (newsletters), reminders (profile updates), etc. I hope I got the point through. - Should be able to process faults (incorrect email address, mail-box full, etc) - User initiated invites (inviting friends to connect) Constraints: - As of now I am looking at Godaddy for hosting. Subsequently I shall move to, may be Amazon Cloud. Godaddy seems to be excruciatingly conservative (not bad always) when it comes to the ability to send email. - My tests on Godaddy so far have been discouraging. There is limit to no. of emails I can send and sometimes if emails carries special characters it throws strange exceptions like there was a virus affected attachment (even though I hadn't attached a thing). The replies from Godaddy support have been equally funny. My intent is not to portray Godaddy as wrong but I am looking for a work-around that frees me from said constraints. I am looking for a mechanism / service that is either free of very cost effective. I wonder how other sites address this. Mine is a .Net / Windows based application.

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  • ASP.NET Routing - load routes from database?

    - by ropstah
    Is it possible to load routes from the database with ASP.NET ? For each r as SomeRouteObject in RouteDataTable routes.MapRoute( _ r.Name, _ r.RouteUri, _ r.RouteValues, _ //?? r.Constraints _ //?? ) Next How should I store the routevalues / constraints? I understand that there are several 'default' routevalues like .Controller and .Action, however I also need entirely custom ones like .Id or .Page...

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  • Default Value or Binding in "Transfer SQL Server Object Task"

    - by Kronass
    Hi, I want to move 500 table from Database to other with their data and constraints all the tables have column who has default value, I used SSIS using "Transfer SQL Server Object Task" and I choose to copy all tables, copy data and primary keys, it copies the table except the default bindings I tried in SQL Server 2008 CopyAllDRIObjects Property but still the same result. How can I copy all tables from database to other with their data and maintaining their constraints.

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