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• Session serialization in JavaEE environment

  - by Ionut

  Please consider the following scenario: We are working on a JavaEE project for which the scalability starts to become an issue. Up until now, we were able to scale up but this is no longer an option. Therefore we need to consider scaling out and preparing the App for a clustered environment. Our main concern right now is serializing the user sessions. Sadly, we did not consider from the beginning the issue and we are encountering the following excetion: java.io.WriteAbortedException: writing aborted; java.io.NotSerializableException: org.apache.catalina.session.StandardSessionFacade I did some research and this exception is thrown because there are objects stored on the session which does not implement the Serializable interface. Considering that all over the app there are quite a few custom objects which are stored on the session without implementing this interface, it would require a lot of tedious work and dedication to fix all these classes declaration. We will fix all this declarations but the main concern is that, in the future, there may be a developer which will add a non Serializable object on the session and break the session serialization & replication over multiple nodes. As a quick overview of the project, we are developing using a home grown framework based on Struts 1 with the Servlet 3.0 API. This means that at this point, we are using the standard session.getAttribute() and session.setAttribute() to work with the session and the session handling is scattered all over the code base. Besides updating the classes of the objects stored on session and making sure that they implement the Serializable interface, what other measures of precaution should we take in order to ensure a reliable Session replication capability on the Application layer? I know it is a little bit late to consider this but what would be the best practice in this case? Furthermore, are there any other issues we should consider regarding this transition? Thank you in advance!

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• Producer-consumer pattern with consumer restrictions

  - by Dan

  I have a processing problem that I am thinking is a classic producer-consumer problem with the two added wrinkles that there may be a variable number of producers and there is the restriction that no more than one item per producer may be consumed at any one time. I will generally have 50-100 producers and as many consumers as CPU cores on the server. I want to maximize the throughput of the consumers while ensuring that there are never more than one work item in process from any single producer. This is more complicated than the classic producer-consumer problem which I think assumes a single producer and no restriction on which work items may be in progress at any one time. I think the problem of multiple producers is relatively easily solved by enqueuing all work items on a single work queue protected by a critical section. I think the restriction on simultaneously processing work items from any single producer is harder because I cannot think of any solution that does not require each consumer to notify some kind of work dispatcher that a particular work item has been completed so as to lift the restriction on work items from that producer. In other words, if Consumer2 has just completed WorkItem42 from Producer53, there needs to be some kind of callback or notification from Consumer2 to a work dispatcher to allow the work dispatcher to release the next work item from Producer53 to the next available consumer (whether Consumer2 or otherwise). Am I overlooking something simple here? Is there a known pattern for this problem? I would appreciate any pointers.

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• What can be done to decrease the number of live issues with applications?

  - by User Smith

  First off I have seen this post which is slightly similar to my question. : What can you do to decrease the number of deployment bugs of a live website? Let me layout the situation for you. The team of programmers that I belong to have metrics associated with our code. Over the last several months our errors in our live system have increased by a large amount. We require that our updates to applications be tested by at least one other programmer prior to going live. I personally am completely against this as I think that applications should be tested by end users as end users are much better testers than programmers, I am not against programmers testing, obviously programmers need to test code, but they are most of the times too close to the code. The reason I specify that I think end users should test in our scenario is due to the fact that we don't have business analysts, we just have programmers. I come from a background where BAs took care of all the testing once programmers checked off it was ready to go live. We do have a staging environment in place that is a clone of the live environment that we use to ensure that we don't have issues between development and live environments this does catch some bugs. We don't do end user testing really at all, I should say we don't really have anyone testing our code except programmers, which I think gets us into this mess (Ideally, we would have BAs or QA or professional testers test). We don't have a QA team or anything of that nature. We don't have test cases for our projects that are fully laid out. Ok, I am just a peon programmer at the bottom of the rung, but I am probably more tired of these issues than the managers complaining about them. So, I don't have the ability to tell them you are doing it all wrong.....I have tried gentle pushes in the correct direction. Any advice or suggestions on how to alleviate this issue ?

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• How to handle editing a large file for a non-technical user

  - by Luke

  I have a client who is given a tab delimited .txt file containing hundreds of thousands of rows. I have a user story as follows: As a user I want to take the text file and add a new value at the end of each line which contains the concatenated value of two of the columns. for example if the file read text_one text_two I need to output the following (preferably to a .txt file) text_one text_two text_onetext_two My first approach was to ask the vendor supplying the file to do the concatenation before providing the file, the easiest way to solve a problem is to eliminate it right? however they are very uncooperative and have point blank refused. I've looked at building a simple javascript application that does this client side so a non-technical user could select the file using a file selector. This approach has a few problems The file could be over a GB in size and so can't be loaded straight into memory, I've tried and the browser crashes There is no means to write a file in javascript so I'd need to output the content to the screen and have the user save it (somehow) I was thinking if I could get around the filesize limitations I could just output the edited content to the page and have the user save the page as a .txt file, however I think there is a better way than using javascript that will still accommodate the users lack of technical know-how. Please consider this question to be stack agnostic, but bear in mind that a nice little shell script or python script would be deemed unsuitable for a non technical user unless there is a way of "packaging" it nicely for a non-technical user. Updates The file is too large to open in excel. The process needs to be run weekly, but it doesn't require scheduling or automation...(yet)

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• Custom field names in Rails error messages

  - by Madhan ayyasamy

  The defaults in Rails with ActiveRecord is beautiful when you are just getting started and are created everything for the first time. But once you get into it and your database schema becomes a little more solidified, the things that would have been easy to do by relying on the conventions of Rails require a little bit more work.In my case, I had a form where there was a database column named “num_guests”, representing the number of guests. When the field fails to pass validation, the error messages is something likeNum guests is not a numberNot quite the text that we want. It would be better if it saidNumber of guests is not a numberAfter doing a little bit of digging, I found the human_attribute_name method. You can override this method in your model class to provide alternative names for fields. To change our error message, I did the followingclass Reservation ... validates_presence_of :num_guests ... HUMAN_ATTRIBUTES = { :num_guests = "Number of guests" } def self.human_attribute_name(attr) HUMAN_ATTRIBUTES[attr.to_sym] || super endendSince Rails 2.2, this method is used to support internationalization (i18n). Looking at it, it reminds me of Java’s Resource Bundles and Spring MVC’s error messages. Messages are defined based off a key and there’s a chain of look ups that get applied to resolve an error’s message.Although, I don’t see myself doing any i18n work in the near-term, it is cool that we have that option now in Rails.

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• Does immutability entirely eliminate the need for locks in multi-processor programming?

  - by GlenPeterson

  Part 1 Clearly Immutability minimizes the need for locks in multi-processor programming, but does it eliminate that need, or are there instances where immutability alone is not enough? It seems to me that you can only defer processing and encapsulate state so long before most programs have to actually DO something. If a program performs actions on multiple processors, something needs to collect and aggregate the results. All this involves multi-process communication before, after, and possibly during some transformations. The start and end state of the machines are different. Can this always be done with no locks just by throwing out each object and creating a new one instead of changing the original (a crude view of immutability)? What cases still require locking? I'm interested in both the theoretical/academic answer and the practical/real-world answer. I know a lot of functional programmers like to talk about "no side effect" but in the "real world" everything has a side effect. Every processor click takes time and electricity and machine resources away from other processes. So I understand that there may be more than one perspective to answer this question from. If immutability is safe, given certain bounds or assumptions, I want to know what the borders of the "safety zone" are exactly. Some examples of possible boundaries: I/O Exceptions/errors Interfaces with programs written in other languages Interfaces with other machines (physical, virtual, or theoretical) Special thanks to @JimmaHoffa for his comment which started this question! Part 2 Multi-processor programming is often used as an optimization technique - to make some code run faster. When is it faster to use locks vs. immutable objects? Given the limits set out in Amdahl's Law, when can you achieve better over-all performance (with or without the garbage collector taken into account) with immutable objects vs. locking mutable ones? Summary I'm combining these two questions into one to try to get at where the bounding box is for Immutability as a solution to threading problems.

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• Tips for achieving "continual" delivery

  - by Ben

  A team is experiencing difficulty releasing software on a frequent basis (once every week). What follows is a typical release timeline: During the iteration: Developers work on stories on the backlog on short-lived (this is enthusiastically enforced) feature branches based on the master branch. Developers frequently pull their feature branches into the integration branch, which is continually built and tested (as far as the test coverage goes) automatically. The testers have the ability to auto-deploy integration to a staging environment and this occurs multiple times per week, enabling continual running of their test suites. Every Monday: there is a release planning meeting to determine which stories are "known good" (based on the testers' work), and hence will be in the release. If there is a known issue with a story, the source branch is pulled out of integration. no new code (only bug fixes requested by the testers) may be pulled into integration on this Monday to ensure the testers have a stable codebase to cut a release from. Every Tuesday: The testers have tested the integration branch as much as they possibly can have given the time available and there are no known bugs so a release is cut and pushed out to the production nodes slowly. This sounds OK in practise, but we have found that it is incredibly difficult to achieve. The team sees the following symptoms "subtle" bugs are found on production that were not identified on the staging environment. last minute hot-fixes continue into the Tuesday. problems on the production environment require roll-backs which blocks continued development until a successful live deployment is achieved and the master branch can be updated (and hence branched from). I think test coverage, code quality, ability to regression test quickly, last minute changes and environmental differences are at play here. Can anyone offer any advice regarding how best to achieve "continual" delivery?

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• Is it common for a development position to be extremely mundane and not challenging at all? [closed]

  - by Kim Jong Woo

  Hi guys so I am working at this company as a web developer but after 1 week of working here, I realize the stuff I am doing seem to be very easy stuff compared to what my peers who have been around for longer are doing. I am way ahead of my schedule and finish my projects early but it's because the work is not at all hard or problem solving involved. So I am puzzled why I would be thanked over doing such menial tasks. Is this normal? This is driving me nuts, I ask to be given more work and I do get it and still finish it quickly and accurately. Now I am having this paranoia that they are just conspiring to use me for a short period of time and terminate me. Am I going too far with this? I keep losing sleep over this. On days when I have a full load of work to complete, this uneasiness goes away but so far I feel like I am not being allowed to pursue what I thought I would do like solving and designing solutions. A lot of it doesn't require any thinking, just cleaning up other people's code and closing bug tickets.

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• Most effective work habit for coding? [on hold]

  - by Cris

  Working on a big solo project (~15,000 LOC), I am encountering the following phenomenon: I seem to work best when I program in short bursts of 10-15 minutes. Right now I am working on a section which is a complete first time for me architecturally and if I have any architectural issues that emerge when doing the implementation, I seem to be able to best serve these by taking a total break. Then, later, sketching out the ideas on some paper. And when I feel I have sufficient clarity, then going back to code. This iterates until that architectural issue for that section is resolved. This seems quite counter intuitive: that I can progress more quickly by coding less, and taking more breaks. I am nearing the end of the sections which are "first times" for me, and about to dive into stuff which I am much more familiar and am wondering if this counter intuitive efficiency will continue. So my question is: even for regular coding of sections one is familiar with, which don't require constant re-clarification of the best architecture, is more progress to be attained by taking more breaks and coding in bursts?

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• Intelligent Conflict Detection and Resolution

  - 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;} Conflict Detection and Resolution in Oracle GoldenGate11gR2 has gone through a significant overhaul. The improvements that have been made to this area are substantial and will make it easier for customers to implement complex, heterogeneous GoldenGate configurations. GoldenGate has provided methods for conflict detection and resolution for a number of past releases, but at Oracle we have the opportunity to take advantage of some of the great ideas in this area. Oracle has had feature rich conflict detection and resolution framework in other products, which has been implemented in Oracle GoldenGate 11gR2. These improvements are geared toward helping customers more easily implement advanced configurations that require conflict detection and resolution by providing a robust framework for conflict detection for all DML statements and resolution via pre-built methods, all with less code and simpler syntax than in prior releases. Conflict Detection and Resolution in Oracle GoldenGate 11gR2 is available for our supported heterogeneous platforms, which includes Oracle Database, MySQL, Sybase ASE, SQL Server, and DB2 Linux, Unix, Windows, z/OS, plus DB2 on i Series, which is newly supported in this release. Additional information on the Conflict Detection and Resolution capabilities can be found in our documentation. 

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• GLSL billboard move center of rotation

  - by Jacob Kofoed

  I have successfully set up a billboard shader that works, it can take in a quad and rotate it so it always points toward the screen. I am using this vertex-shader: void main(){ vec4 tmpPos = (MVP * bufferMatrix * vec4(0.0, 0.0, 0.0, 1.0)) + (MV * vec4( vertexPosition.x * 1.0 * bufferMatrix[0][0], vertexPosition.y * 1.0 * bufferMatrix[1][1], vertexPosition.z * 1.0 * bufferMatrix[2][2], 0.0) ); UV = UVOffset + vertexUV * UVScale; gl_Position = tmpPos; BufferMatrix is the model-matrix, it is an attribute to support Instance-drawing. The problem is best explained through pictures: This is the start position of the camera: And this is the position, looking in from 45 degree to the right: Obviously, as each character is it's own quad, the shader rotates each one around their own center towards the camera. What I in fact want is for them to rotate around a shared center, how would I do this? What I have been trying to do this far is: mat4 translation = mat4(1.0); translation = glm::translate(translation, vec3(pos)*1.f * 2.f); translation = glm::scale(translation, vec3(scale, 1.f)); translation = glm::translate(translation, vec3(anchorPoint - pos) / vec3(scale, 1.f)); Where the translation is the bufferMatrix sent to the shader. What I am trying to do is offset the center, but this might not be possible with a single matrix..? I am interested in a solution that doesn't require CPU calculations each frame, but rather set it up once and then let the shader do the billboard rotation. I realize there's many different solutions, like merging all the quads together, but I would first like to know if the approach with offsetting the center is possible. If it all seems a bit confusing, it's because I'm a little confused myself.

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• Does TDD's "Obvious Implementation" mean code first, test after?

  - by natasky

  My friend and I are relatively new TDD and have a dispute about the "Obvious Implementation" technique (from "TDD By Example" by Kent Beck). My friend says it means that if the implementation is obvious, you should go ahead and write it - before any test for that new behavior. And indeed the book says: How do you implement simple operations? Just implement them. Also: Sometimes you are sure you know how to implement an operation. Go ahead. I think what the author means is you should test first, and then "just implement" it - as opposed to the "Fake It ('Till You Make It)" and other techniques, which require smaller steps in the implementation stage. Also after these quotes the author talks about getting "red bars" (failing tests) when doing "Obvious Implementation" - how can you get a red bar without a test?. Yet I couldn't find any quote from the book saying "obvious" still means test first. What do you think? Should we test first or after when the implementation is "obvious" (according to TDD, of course)? Do you know a book or blog post saying just that?

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• PHP/MySQL Database application development tool

  - by RCH

  I am an amateur PHP coder, and have built a couple of dozen projects from scratch (including fairly simple e-commerce systems with user authentication, PayPal integration etc - all coded by hand from a clean page. Have also done a price comparison engine that takes data from multiple sites etc.). But I am no expert with OO and other such advanced techniques - I just have a fairly decent grasp of the basics of data processing, logic, functions and trying to optimize code as much as possible. I just want to make this clear so you have some idea of where I'm coming from. I have a couple of fairly large new projects on my plate for corporate clients - both require bespoke database-driven applications with complex relationships, many tables and lots of different front-end functions to manipulate that data for the internal staff in these companies. I figured building these systems from scratch would probably be a huge waste of time. Instead, there must be tools out there that will allow me to construct MySQL databases and build the pages with things like pagination, action buttons, table construction etc. Some kind of database abstraction layer, or system generator, if you will. What tool do you recommend for such a purpose for someone at my level? Open source would be great, but I don't mind paying for something decent as well. Thanks for any advice.

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• Technology Choice for a Client Application [on hold]

  - by AK_

  Not sure this is the right place to ask... I'm involved in the development of a new system, and now we are passing the demos stage. We need to build a proper client application. The platform we care most about is Windows, for now at least, but we would love to support other platforms, as long as it's free :-). Or at least very cheap. We anticipate two kinds of users: Occasional, coming mostly from the web. Professional, who would probably require more features, and better performance, and probably would prefer to see a native client. Our server exposes two APIs: A SOAP API, WCF behind the scenes, that supports 100% of the functionality. A small and very fast UDP + Binary API, that duplicates some of the functionality and is intended for the sake of performance for certain real-time scenarios. Our team is mostly proficient in .Net, C#, C++ development, and rather familiar with Web development (HTML, JavaScript). We are probably intending to develop two clients (for both user profiles), a web app, and a native app. Architecturally, we would like to have as many common components as possible. We would like to have several layers: Communication, Client Model, Client Logic, shared by both of the clients. We would also like to be able to add features to both clients when only the actual UI is a dual cost, and the rest is shared. We are looking at several technologies: WPF + Silverlight, Pure HTML, Flash / Flex (AIR?), Java (JavaFx?), and we are considering poking at WinRT(or whatever the proper name is). The question is which technology would you recommend and why? And which advantages or disadvantages will it have regarding our requirements?

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• Restrictive routing best practices for Google App Engine with python?

  - by Aleksandr Makov

  Say I have a simple structure: app = webapp2.WSGIApplication([ (r'/', 'pages.login'), (r'/profile', 'pages.profile'), (r'/dashboard', 'pages.dash'), ], debug=True) Basically all pages require authentication except for the login. If visitor tries to reach a restrictive page and he isn't authorized (or lacks privileges) then he gets redirected to the login view. The question is about the routing design. Should I check the auth and ACL privs in each of the modules (pages.profile and pages.dash from example above), or just pass all requests through the single routing mechanism: app = webapp2.WSGIApplication([ (r'/', 'pages.login'), (r'/.+', 'router') ], debug=True) I'm still quite new to the GAE, but my app requires authentication as well as ACL. I'm aware that there's login directive on the server config level, but I don't know how it works and how I can tight it with my ACL logic and what's worse I cannot estimate time needed to get it running. Besides, it looks only to provide only 2 user groups: admin and user. In any case, that's the configuration I use: handlers: - url: /favicon.ico static_files: static/favicon.ico upload: static/favicon.ico - url: /static/* static_dir: static - url: .* script: main.app secure: always Or I miss something here and ACL can be set in the config file? Thanks.

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• Topeka Dot Net User Group (DNUG) Meeting &ndash; April 6, 2010

  - by Robz / Fervent Coder

  Topeka DNUG is free for anyone to attend! Mark your calendars now! SPEAKER: Troy Tuttle is a self-described pragmatic agilist, and Kanban practitioner, with more than a decade of experience in delivering software in the finance and health industries and as a consultant. He advocates teams improve their performance through pursuit of better practices like continuous integration and automated testing. Troy is the founder of the Kansas City Limited WIP Society and is a speaker at local area groups on team related topics. He currently works as a Project Lead Consultant with AdventureTech Group of Kansas City, KS. TOPIC: Why Kanban? Kanban is receiving a large amount of attention recently. What does it offer compared to other approaches? Answering that question may require you to hit the “reset” button on previously held biases and assumptions. Kanban blends Lean thought with ideas from first generation agile methodologies. To get started with Kanban, we will examine what steps are necessary to establish a transparent, work-limited, pull system. We will highlight the perils of allowing too much work-in-progress and how it affects development performance. Once established, Kanban teams need only a few metrics and tools to monitor their performance and improvement. WHERE: Federal Home Loan Bank Topeka on the Security Benefit Campus – Directions? WHEN: 11:30 AM - 1:00 PM on April 6th, 2010 REGISTER: http://topekadotnet.wufoo.com/forms/topeka-dnug-meeting-attendance/ ADDITIONAL INFO: As always, please sign in and out of FHLBank to help them with their accountability. Please park in the visitors section at the front of the building when you arrive. If  there are no spots in visitors you may park in the overflow lot at the far east end of the facility.  Lunch will be provided and we will have some great door prizes!

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• Create MSDB Folders Through Code

  You can create package folders through SSMS, but you may also wish to do this as part of a deployment process or installation. In this case you will want programmatic method for managing folders, so how can this be done? The short answer is, go and look at the table msdb.dbo. sysdtspackagefolders90. This where folder information is stored, using a simple parent and child hierarchy format. To add new folder directly we just insert into the table - INSERT INTO dbo.sysdtspackagefolders90 ( folderid ,parentfolderid ,foldername) VALUES ( NEWID() -- New GUID for our new folder ,<<Parent Folder GUID>> -- Lookup the parent folder GUID if a child or another folder, or use the root GUID 00000000-0000-0000-0000-000000000000 ,<<Folder Name>>) -- New folder name There are also some stored procedures - sp_dts_addfolder sp_dts_deletefolder sp_dts_getfolder sp_dts_listfolders sp_dts_renamefolder To add a new folder to the root we could call the sp_dts_addfolder to stored procedure - EXEC msdb.dbo.sp_dts_addfolder @parentfolderid = '00000000-0000-0000-0000-000000000000' -- Root GUID ,@name = 'New Folder Name The stored procedures wrap very simple SQL statements, but provide a level of security, as they check the role membership of the user, and do not require permissions to perform direct table modifications.

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• Data Management Business Continuity Planning

  Business Continuity Governance In order to ensure data continuity for an organization, they need to ensure they know how to handle a data or network emergency because all systems have the potential to fail. Data Continuity Checklist: Disaster Recovery Plan/Policy Backups Redundancy Trained Staff Business Continuity Policies In order to protect data in case of any emergency a company needs to put in place a Disaster recovery plan and policies that can be executed by IT staff to ensure the continuity of the existing data and/or limit the amount of data that is not contiguous.  A disaster recovery plan is a comprehensive statement of consistent actions to be taken before, during and after a disaster, according to Geoffrey H. Wold. He also states that the primary objective of disaster recovery planning is to protect the organization in the event that all or parts of its operations and/or computer services are rendered unusable. Furthermore, companies can mandate through policies that IT must maintain redundant hardware in case of any hardware failures and redundant network connectivity incase the primary internet service provider goes down.  Additionally, they can require that all staff be trained in regards to the Disaster recovery policy to ensure that all parties evolved are knowledgeable to execute the recovery plan. Business Continuity Procedures Business continuity procedure vary from organization to origination, however there are standard procedures that most originations should follow. Standard Business Continuity Procedures Backup and Test Backups to ensure that they work Hire knowledgeable and trainable staff  Offer training on new and existing systems Regularly monitor, test, maintain, and upgrade existing system hardware and applications Maintain redundancy regarding all data, and critical business functionality

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• Refactoring and Open / Closed principle

  - by Giorgio

  I have recently being reading a web site about clean code development (I do not put a link here because it is not in English). One of the principles advertised by this site is the Open Closed Principle: each software component should be open for extension and closed for modification. E.g., when we have implemented and tested a class, we should only modify it to fix bugs or to add new functionality (e.g. new methods that do not influence the existing ones). The existing functionality and implementation should not be changed. I normally apply this principle by defining an interface I and a corresponding implementation class A. When class A has become stable (implemented and tested), I normally do not modify it too much (possibly, not at all), i.e. If new requirements arrive (e.g. performance, or a totally new implementation of the interface) that require big changes to the code, I write a new implementation B, and keep using A as long as B is not mature. When B is mature, all that is needed is to change how I is instantiated. If the new requirements suggest a change to the interface as well, I define a new interface I' and a new implementation A'. So I, A are frozen and remain the implementation for the production system as long as I' and A' are not stable enough to replace them. So, in view of these observation, I was a bit surprised that the web page then suggested the use of complex refactorings, "... because it is not possible to write code directly in its final form." Isn't there a contradiction / conflict between enforcing the Open / Closed Principle and suggesting the use of complex refactorings as a best practice? Or the idea here is that one can use complex refactorings during the development of a class A, but when that class has been tested successfully it should be frozen?

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• Using Google App Engine to Perform World Updates vs an Authoritative Server

  - by Error 454

  I am considering different game server architectures that use GAE. The types of games I am considering are turn-based where the world status would need to be updated about once per minute. I am looking for an answer that persuades me to either perform the world update on the google servers OR an authoritative server that syncs with the datastore. The main goal here would be to minimize GAE daily quotas. For some rough numbers, I am assuming 10,000 entities requiring updates. Each entity update would require: Reading 5 private entity variables (fetched from datastore) Fetching as many as 20 static variables (from datastore or persisted in server memory) Writing 5 entity variables Clients of the game would authenticate and set state directly against GAE as well as pull the latest world state from GAE. Running the update on GAE would consist of a cron job launched every minute. This would update all of the entities and save the results to the datastore. This would be more CPU intensive for GAE. Running the update on an authoritative server would consist of fetching entity data from the GAE datastore, calculating the new entity states and pushing the new state variables back to the datastore. This would be more bandwidth intensive for the datastore.

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• How can I discourage the use of Access?

  - by Greg Buehler

  Lets pretend that a very large company (revenue numbers with more than 8 figures) is looking to do a refresh on a software system, particularly the dashboard used by employees. This system was originally put together in the early 1990's to handle inventory tracking and storage across a variety of facilities (10+). Since this large company is now in the process of implementing some of these inventory processes with SAP they are in need of a major refresh. The existing system: Microsoft Access project performs dashboard duties Unique shipping/receiving configurations at different facilities require unique forms and queries within the Access project Uses 3rd party libraries referenced by Access to directly interface with at control system (read: motors, conveyors, and counters) Individual SQL Server 2000 instances (some traces of pre-update SQL Server 6.0 documents) at each facility The Issue: This system started as a home brewed inventory tracking scheme with a single internal sponsor who is still in charge of the technical direction. The original sponsor prescribing the desired deliverables that are being called for in the current RFP. The RFP describes a system based around a single Access project. Any suggestion that Access is ill suited for a project of this scope are shot down under the reasoning that "it works for the scope now". Are there any case studies, notices, or statements that can be used to disuade this potential customer from repeating their mistake? Does Microsoft make any statements directly about when it is highly recommended to ditch Access?

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• Initializing entities vs having a constructor parameter

  - by Vee

  I'm working on a turn-based tile-based puzzle game, and to create new entities, I use this code: Field.CreateEntity(10, 5, Factory.Player()); This creates a new Player at [10; 5]. I'm using a factory-like class to create entities via composition. This is what the CreateEntity method looks like: public void CreateEntity(int mX, int mY, Entity mEntity) { mEntity.Field = this; TileManager.AddEntity(mEntity, true); GetTile(mX, mY).AddEntity(mEntity); mEntity.Initialize(); InvokeOnEntityCreated(mEntity); } Since many of the components (and also logic) of the entities require to know what the tile they're in is, or what the field they belong to is, I need to have mEntity.Initialize(); to know when the entity knows its own field and tile. The Initialize(); method contains a call to an event handler, so that I can do stuff like this in the factory class: result.OnInitialize += () => result.AddTags(TDLibConstants.GroundWalkableTag, TDLibConstants.TrapdoorTag); result.OnInitialize += () => result.AddComponents(new RenderComponent(), new ElementComponent(), new DirectionComponent()); This works so far, but it is not elegant and it's very open to bugs. I'm also using the same idea with components: they have a parameterless constructor, and when you call the AddComponent(mComponent); method in an entity, it is the entity's job to set the component's entity to itself. The alternative would be having a Field, int, int parameters in the factory class, to do stuff like: new Entity(Field, 10, 5); But I also don't like the fact that I have to create new entities like this. I would prefer creating entities via the Field object itself. How can I make entity/component creation more elegant and less prone to bugs?

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• How to analyze data

  - by Subhash Dike

  We are working on an application that allows user to search/read some content in a particular domain. We wanted to add some capability in the app which can suggest user some content based on the usage pattern (analyze data based on frequency and relevance). Currently every time user search or read something we do store that information in backend database. We would like to use this data to present some additional content to user. Could someone explain what kind of tools will be required for such a job and any example? And what this concept is called, data analysis? data mining? business intelligence? or something else? Update: Sorry for being too broad, here is an example SQL Database (Just to give an idea, actual db is little different with normalization and stuff) Table: UserArticles Fields: UserName | ArticleId | ArticleTitle | DateVisited | ArticleCategory Table: CategoryArticles Fields: Category | Article Title | Author etc. One Category may have one more articles. One user may have read the same article multiple times (in this case we place additional entry in the user article table. Task: Use the information availabel in UserArticle table and rank categories in order which would be presented to user automatically in other part of application. Factors to be considered are frequency and recency. This might be possible through simple queries or may require specialized tools. Either way, the task is what mention above. I am not too sure which route to take, hence the question. Thoughts??

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• Fun Upgrading to .Net 4.0

  - by Sam Abraham

  We are currently in the process of upgrading one of our applications to .Net 4.0. Aside from us geeks wanting to always use latest and greatest technologies, an immediate business need for Silverlight 4.0 features justified our upgrade endeavor. The following is a summary of some issues we ran into with our web project:   For security purposes, the IIS 7 .Net 4.0 ISAPI filter is disabled. “Allow” it from the ISAPI and CGI Restrictions screen as shown:   Figure 1 - Allowing ASP.Net 4.0 ISAPI Filter   By default the Web Setup Project only requires the .Net Framework 4 Client Profile to be installed on target system, which offers a lighter weight install for client machines consuming .Net 4.0 applications. However, using certain .Net 4.0 features requires the full .Net 4.0 Framework as outlined in this link: http://msdn.microsoft.com/en-us/library/cc656912.aspx. We hence needed to update the installer to require the complete .Net 4.0 Framework on the target machine and to prompt for its installation if needed.   To accomplish this goal, we updated the installer’s launch conditions to check for .Net 4.0 as well as the installer prerequisites as shown:     Figure 2- Ensure Web Setup Project runs on full .Net 4.0 version Figure 3 - Launch Conditions screen Figure 4 - Set launch condition to .Net 4.0. Figure 5 -Changing installer prerequisites Figure 6 -Changing installer prerequisites

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• Is my concept in open source license correct?

  - by tester

  I would like to justify whether my concept in the open source license is correct, as you know that, misunderstanding the terms may lead to a serious law sue. Thank you. The main difference among the open source license is whether the license is copyleft. Copyleft license means allow the others to reproduce, modify and distribute the products but the released product is bound by the same licensing restriction. That means they have to use the same license for the modified version. Also, the copyleft license require all the released modified version to be free software. On the other hand, if any others create derived work incorporating non-copyleft licensed code, they can choose any license for the code. The serveral kinds of license and comparsion GPL is a restrictive license. Software requires to released as GPL license if that integrate or is modified from the other GPL license software . The library used in developing GPL license software are also restricted to GPL and LGPL , proprietary software are not allowed to employ (or complied with) in any part of the GPL application. LGPL is similar to GPL , but was more permissive with regarding allow the using of other non-GPL software. BSD is relatively simple license, it allow developer to do anything on the original source code . The license holder do not hold any legal responsibilities for their released product. Apache license is evolved from the BSD license. The legal terms are improved and are written by legal professionals in a more modern way. It covers comprehensive intellectual property ownership and liability issues. Also, are there any popular license beside these? Thank you

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