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• How can I set a Windows user environment variable that takes effect for the current session?

  - by Graham Powell

  I am trying to set a Windows user environment variable and then launch an application via either batch file or a script. However, the environment variable is not set to the appropriate value until after the user logs off and logs back on. (I think a more accurate description would be that the new value is not available to the app until after the next logon.) Is there any way to set a variable in the user's environment so that it's immediately available? I'm doing this because this program's functionality can be controlled by environment variables, and users will need different functionality at different times. Because of license constraints I need to set this dynamically, if possible. Thanks, Graham

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• Best CMS to handle short snippets of text?

  - by Federico Poloni

  I have to install a CMS to manage a set of mathematical problems, i.e., our main content will be short (~3 lines) snippets of text. We need the ability to add comments and categories/tags, possibly with a powerful search function combining different constraints on the categories. A crucial ability is the possibility to combine the results of a search in the same page to produce a (printable) problem sheet: not many CMS's seem to be able to do so, and it is difficult for me to test every one for this specific function. Do you guys know of a CMS that is capable to return formatted search result in this fashion? Thanks in advance!

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• Corporate Wiki Organization - Technical Documentation

  - by Dave Jarvis

  Corporations have documents describing various aspects of their technical systems, including: Custom Applications Custom Development Frameworks Third Party Applications Accounting Bug Tracking Network Management How To Guides User Manuals Software Tools Web Browsers Development IDEs Graphics GIMP xv Text Editing File Transfer ncFTP WinSCP Hardware Servers Web Database Exchange File Network Devices Printers If you had to use a Wiki to manage the documentation, what other items would you add to the list, and how would you organize it? (For example, would Software Tools make more sense under Third Party Applications?) A few constraints: The structure should not go beyond three levels deep. Avoid the word "and" in favour of two different categories. Keep the structure general: it should appy as broadly as possible. Target audience is primarily technical, but could be visible by anyone.

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• Is it easy to update ubuntu beta to ubuntu final release?

  - by Peter Smit

  At this moment I am preparing a virtual server to host a web application which needs php5.3 The virtual server base image is always Hardy (8.04 LTS). There is no php5.3 until the upcoming release in a few days: Lucid (9.04 LTS). I am seeing to options: - waiting until the final version is released and then start preparing this server - Now upgrading to the beta (do-release-upgrade --devel-release) and when the final release has come upgrading to that For time constraints I would prefer the second option. I only can't find whether it will be easy to upgrade from a beta to the 'clean' final release. Is this possible in an easy way. Will it have any drawback for security or will there be any traces left of it being ever a beta release? Note: the server will not go into production before the LTS is really installed.

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• multiple file systems for mysql

  - by RainDoctor

  Does mysql support multiple file systems for a single database with most of the tables being on MyISAM? Context: we have a 1.5TB mysql database, which is increasing at the rate of 200GB per month. The storage is directly attached, whose slots are almost full. I can add another DAS, and increase the file system. But resizing volume, resizing file system, etc are getting messy. Is there a concept of "tablespace, datafile" (like in oracle) in MySql world? Or how you guys manage mysql db with these kind of constraints?

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• sudoer scheme for a web developer that retains future control of a server?

  - by Tchalvak

  Background I have a server that I'm looking to set up, and provide access to another web developer. I don't want to put many constraints on him, though I wouldn't mind isolating the site that he'll be developing from others on the server that I will develop. The problem Mainly what I want is to make sure that I retain control over the server in the future. I want to reserve the ability to create/promote/demote and other administrative functions that don't deal with web software. If I make him an admin, he can sudo su - and become root and remove root control from me, for example. What is a good setup for the sudoers file so that he can do things like: *install software (through apt-get) restart apache access mysql configure mysql/apache reboot edit web development configuration type files in /etc * And can't do things like: take away other admin permissions change the root password have control over other security/administrative functions Example sudoer files that accomplish something like that could be useful, I'm sure that people have needed to do this before.

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• Launch Sublime Text 2 from command line

  - by Erick

  I am trying to launch Sublime Text 2 via command line. I know it has already been done before here but I am having different constraints. I use the portable version of ST and store it into my Dropbox account. I guess you can see me coming here. I need to launch subtext on a relative path. So far it "kinda works" if I type in the command line subl file.txt it works I see the file content but if I type subl "file 2.txt" I do not have nothing it opens ST with something like c:\mydir\"file 2.txt". I guess the problem lies on the "%WORKINGDIR%\%1" of the script bellow. @ECHO OFF SET WORKINGDIR=%CD% cd /d %0\.. SET EXECDIR=%CD% cd %WORKINGDIR% START "Sublime text editor" "%EXECDIR%\sublimetext\sublime_text.exe" "%WORKINGDIR%\%1"

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• Replicating/Synchronizng multiple tables across diffrent Databases on the same instance

  - by Idan

  I have few tables that needed to be replicated/synchronized across several databases in our SQL Server 2008 cluster. I know it's possible to replicate between multiple instances, but I'm looking for replication or synchronization in the same instance between specific tables of databases. The replicaiton/synchronization should happen every half-hour or so, but I don't mind it happening constantly. I can't use DROP the target table and INSERT (copy) the source table since there are many constraints. Reason for this is to not manage in the application layer and write to 2 different databases at the same time. Example: DB1 has T1, T2 and T3 - these are constantly being updated by the application, APP1 running on DB1. DB2 needs to have an updated copy of T1 at all times, also, there is a different application, APP2 runs only on DB2. Both DB1 and DB2 are located on the same instance, INST1. Would it be possible to replicate T1, T2 and T3 from DB1 to DB2 ? Thanks, Idan.

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• ASP.NET MVC hosting recommendations

  - by chris

  I'm looking for recommendations for hosting an asp.net MVC application. Obviously, we need to be able to have access to configure IIS directly - I'd prefer not to have to go thru a control panel. The web server needs to have a dedicated IP, since some clients will be accessing it via IP. We need at least a SQLServer 2005 database, ideally on the same box. Load and usage will be pretty low, so a virtual machine will probably be fine. Does any one have any recommendations that meet the above constraints?

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• Does LDAP fit the role of a user database for an application?

  - by Spredzy

  I (my company) run a webservice that integrates pieces of few entreprisey-level software. Most of them offer different type of authentication but all offers at least LDAP. I was wondering if storing my application users directly in an LDAP directory would be a good idea. This way all the application I am using could rely on it for authentication purpose. I am aware that LDAP is not a database per se, but it is a datastore. I am also aware that there is no kind of constraints thus deleting a user on the LDAP directory won't do anything on my actual data, but this case would be taken care of with an extra process. My main question here is : is there any reason why I shouldn't use LDAP as my users database ?

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• Ways to do simple failover with one server and two IPs

  - by CrassHoppr

  The setup is one server (Windows 2008) at one location with two incoming connections. As the server has to interface with various on-site devices, and will have a small number of incoming connections, a data center is not an option, and instead cable/dsl connections must be used. The goal is that users visit https://service.site.com and are sent to either the primary IP address or a secondary IP if the primary is down. I've seen advice to use round robin DNS for this, but caching an IP for a downed interface is something I'd like to avoid. Is something like this possible with these constraints?

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• Scheduled task giving last run result 0x80041324

  - by SteveC

  I've got a scheduled task set up in my Windows 7 machine which is meant to run a BAT file when I'm not around, i.e. the machine has been idle for 15 minutes. Does anyone know how to track down the cause of the error code ? Checked on MSDN and it says ... SCHED_E_TASK_ATTEMPTED 0x80041324 The Task Scheduler service attempted to run the task, but the task did not run due to one of the constraints in the task definition. And to confuse me even further, I've just noticed it has run while I'm at the machine with last result (0x0)

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• How do I swap audio output of the left and right speakers?

  - by Manga Lee

  I have two speakers stereo speakers but when I use the sound control panel applet to test my audio configuration I get sound in the right speaker when the user interface indicates the right speaker and vice versa. Is there a way to swap the audio output from left to right and right to left? UPDATE: The reason for this question is that I've recently rearranged my workspace and because of physical constraints the left speaker has to go on the right side and vice versa. I could of course solve this problem with a hardware solution but I'd rather use a software solution if one is available.

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• How to start a service at boot time in ubuntu 12.04, run as a different user?

  - by Alex

  I have a server ClueReleaseManager which I have installed on a Ubuntu 12.04 system from a separate user (named pypi), and I want to be able to start this server at startup. I already have tried to create a simple bash script with some commands (login as user pypi, use a virtual python environment, start the server), but this does not work properly. Either the terminal crashes or when I try to ask the status of the service it is started and I am logged in as user pypi ...? So, here the question: What are the steps to take to make sure the ClueReleaseManager service properly starts up on boot time, and which I can control (start/stop/..) during runtime, while the service is running from a user pypi? Additional information and constraints: I want to do this as simple as possible Without any other packages/programs to be installed I am not familiar with the Ubuntu 12.04 init structure All the information I found on the web is very sparse, confusing, incorrect or does not apply to my case of running a service as a different user from root.

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• Identify an instance of Google Chrome by PID

  - by Laramie

  While working I generally need around 40 windows open at a time and run 100-200 processes. When memory constraints become an issue, I start picking off the processes that are the most resource intensive and disposable. Often these are chrome.exe. It would be helpful to be able to match a particularly memory-hungry instance of chrome to it's PID so I can selectively close it. That is, if I knew what the page title it is currently open to, I could choose whether it lives or dies. I've tried Process Explorer to no avail. Any ideas?

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• How to setup wireless radio to network using 2 nics?

  - by CptanPanic

  I am having problems setting up this network, hopefully someone can help me. Laptop <- Wireless Radio <- ... - Wireless Radio <- CPU1( NIC1,NIC2) <- SWITCH <- CPU2 I have a computer with 2 NICs (CPU1). One goes to a wireless radio that connects to a wireless laptop, the other NIC goes to network switch. I can't connect Wireless Radio to switch due to space constraints. All the machines and radios are on same network addresses. I tried using Window's Bridge network which did allow Laptop to reach CPU2, but not CPU1. What is the way to get this to work so all the computers can talk to each other?

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• Home router for higher network loads

  - by Zizzencs

  I'm trying to find a replacement for my ASUS WL500GP router. Some constraints: my ISP now provides 120 Mbit bandwidth - the router must be able to handle it I have 3 computers and a laptop at home - the router must have at least 4 LAN ports and the WAN port I need to be able to do the following in parallel: use bittorrent with ~1000 connections transfer files from one home computer to another at high speed access one home computer from my workplace I don't really need wireless I don't really want two boxes to serve all these purposes. So I was searching for a router with 1 Gbit ports, jumbo frame support and good reviews, but haven't really found a promising candidate so far. Any suggestions?

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• Using LDAP/Active Directory with PIN based authentication

  - by nishantjr

  We'd like to integrate our service with LDAP, but because of hardware constraints, we're only allow 4 digit user ids and passwords. What would be the best practice for performing such an authetication? We've considered adding User ID and PIN attributes to the LDAP user schema, but we're not sure how happy people would be with modifying their schema to interact with our service. The PIN attribute would have to have the same support that native user passwords have. (hashing and salting etc.) UPDATE Another consideration is how ldap_bind works with this scenario. How do we get it to use an alternate authentication method? Can this even be done without affecting other services that use the same LDAP server?

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• vSphere 4 - how can I cancel a file copy in progress?

  - by DrStalker

  VMware vSphere 4 SAN storage with multiple data-stores No vCenter I shut-down a virtual machine and using the data-store browser did a copy/paste to copy the VM to a new datastore with additional space. The file copy performance was very poor, and due to time constraints I decided to cancel the copy task. However the copy task showing in the vsphere client can not be cancelled; the cancel option is disabled. Currently I am not able to start the machine in it's original location as the disk files are locked for the copy. How can I abort the copy? I tried deleting the target directory but this did not abort the copy task.

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• SQL Server 2008 (64-bit)

  - by Grace09

  I have transaction log backup failures randomly. SQL Server Log says 'Memory constraints resulted reduced backup/restore buffer sizes. Proceding with 6 buffers of size 64KB.', and the SQL Server Agent Error Log has quite a few errors like 'Unable to start Job Manager thread for job xxx', '[298] SQLServer Error: 768, Client unable to establish connection [SQLSTATE 08001]', [298] SQLServer Error: 768, SSL Provider: Not enough memory is available to complete this request [SQLSTATE 08001]'. I am really low on the memory? It has total of 32 GB, but I set maximum to 20. Task manager shows it is using 99% of physical memory. Memoryclerk-sqlbufferpool has 32GB for the Virtual Memory Reserved, and 20 GB for the Virtual Memory Committed. From the perfmon, SQLServer:Memory Manager/Total ServerMemory shows 21GB of memory in use, that's what I set the maximum to. I don't where the rest of memory go. Can anyone advice? Thanks in advance.

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• Grails - Simple hasMany Problem - Using CheckBoxes rather than HTML Select in create.gsp

  - by gav

  My problem is this: I want to create a grails domain instance, defining the 'Many' instances of another domain that it has. I have the actual source in a Google Code Project but the following should illustrate the problem. class Person { String name static hasMany[skills:Skill] static constraints = { id (visible:false) skills (nullable:false, blank:false) } } class Skill { String name String description static constraints = { id (visible:false) name (nullable:false, blank:false) description (nullable:false, blank:false) } } If you use this model and def scaffold for the two Controllers then you end up with a form like this that doesn't work; My own attempt to get this to work enumerates the Skills as checkboxes and looks like this; But when I save the Volunteer the skills are null! This is the code for my save method; def save = { log.info "Saving: " + params.toString() def skills = params.skills log.info "Skills: " + skills def volunteerInstance = new Volunteer(params) log.info volunteerInstance if (volunteerInstance.save(flush: true)) { flash.message = "${message(code: 'default.created.message', args: [message(code: 'volunteer.label', default: 'Volunteer'), volunteerInstance.id])}" redirect(action: "show", id: volunteerInstance.id) log.info volunteerInstance } else { render(view: "create", model: [volunteerInstance: volunteerInstance]) } } This is my log output (I have custom toString() methods); 2010-05-10 21:06:41,494 [http-8080-3] INFO bumbumtrain.VolunteerController - Saving: ["skills":["1", "2"], "name":"Ian", "_skills":["", ""], "create":"Create", "action":"save", "controller":"volunteer"] 2010-05-10 21:06:41,495 [http-8080-3] INFO bumbumtrain.VolunteerController - Skills: [1, 2] 2010-05-10 21:06:41,508 [http-8080-3] INFO bumbumtrain.VolunteerController - Volunteer[ id: null | Name: Ian | Skills [Skill[ id: 1 | Name: Carpenter ] , Skill[ id: 2 | Name: Sound Engineer ] ]] Note that in the final log line the right Skills have been picked up and are part of the object instance. When the volunteer is saved the 'Skills' are ignored and not commited to the database despite the in memory version created clearly does have the items. Is it not possible to pass the Skills at construction time? There must be a way round this? I need a single form to allow a person to register but I want to normalise the data so that I can add more skills at a later time. If you think this should 'just work' then a link to a working example would be great. If I use the HTML Select then it works fine! Such as the following to make the Create page; <tr class="prop"> <td valign="top" class="name"> <label for="skills"><g:message code="volunteer.skills.label" default="Skills" /></label> </td> <td valign="top" class="value ${hasErrors(bean: volunteerInstance, field: 'skills', 'errors')}"> <g:select name="skills" from="${uk.co.bumbumtrain.Skill.list()}" multiple="yes" optionKey="id" size="5" value="${volunteerInstance?.skills}" /> </td> </tr> But I need it to work with checkboxes like this; <tr class="prop"> <td valign="top" class="name"> <label for="skills"><g:message code="volunteer.skills.label" default="Skills" /></label> </td> <td valign="top" class="value ${hasErrors(bean: volunteerInstance, field: 'skills', 'errors')}"> <g:each in="${skillInstanceList}" status="i" var="skillInstance"> <label for="${skillInstance?.name}"><g:message code="${skillInstance?.name}.label" default="${skillInstance?.name}" /></label> <g:checkBox name="skills" value="${skillInstance?.id.toString()}"/> </g:each> </td> </tr> The log output is exactly the same! With both style of form the Volunteer instance is created with the Skills correctly referenced in the 'Skills' variable. When saving, the latter fails with a null reference exception as shown at the top of this question. Hope this makes sense, thanks in advance! Gav

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• Grails validation problems with sets of data: only getting one error message for all errors in a set

  - by Matt

  Hi, I'm trying to validate a domain class that has a number of subsets. class IebeUser { ... static hasMany = [openUserAnswers:OpenUserAnswer, closedUserAnswers:ClosedUserAnswer] } class OpenUserAnswer { OpenQuestion openQuestion String text static belongsTo = [user:IebeUser] static constraints = { openQuestion(nullable:false) text(blank:false) } } class ClosedUserAnswer { ClosedQuestion closedQuestion ClosedAnswer answer static belongsTo = [user:IebeUser] static constraints = { closedQuestion(nullable:false) answer(nullable:false) } } A closed question has a set of predefined answers and an open question lets the user enter a freeform answer. All is well until I come to validate the object after entry in a form: params: [closedUserAnswers[0].answer.id:, closedUserAnswers[0]:[answer:[id:], answer.id:], password:dfgdfgdf, openUserAnswers[0].text:gdfgdfgdfg, openUserAnswers[0]:[text:gdfgdfgdfg], _isOptedOut:, create:Continue, username:gdfgdfggdf, email:[email protected], closedUserAnswers[1].answer.id:, closedUserAnswers[1]:[answer:[id:], answer.id:], openUserAnswers[1].text:, openUserAnswers[1]:[text:], firstName:dfgdf, lastName:gdfgdfgd, action:save, controller:main] The key bits being: closedUserAnswers[0].answer.id:, closedUserAnswers[0]:[answer:[id:] closedUserAnswers[1].answer.id:, closedUserAnswers[1]:[answer:[id:] openUserAnswers[1].text:, openUserAnswers[1]:[text:] In my tests I have two objects of type closedUserAnswers and two of openUserAnswers. But when I call validation on IebeUser I only get validation errors for the closedUserAnswers or the openUserAnswers as a whole. I don't get validation errors for each object with a problem which is what I need. I really need an error per instance. Does anyone know what I'm doing wrong? Even when I call the validate method against each closedUserAnswer/openUserAnswer I still only get one per type. Here are my errors. Sorry for all the code, but thought I'd include as much of the code as possible so that it makes sense. Field error in object 'uk.co.cascaid.iebe.IebeUser' on field 'openUserAnswers.text': rejected value []; codes [uk.co.cascaid.iebe.OpenUserAnswer.text.blank.error.uk.co.cascaid.iebe.IebeUser.openUserAnswers.text,uk.co.cascaid.iebe.OpenUserAnswer.text.blank.error.openUserAnswers.text,uk.co.cascaid.iebe.OpenUserAnswer.text.blank.error.text,uk.co.cascaid.iebe.OpenUserAnswer.text.blank.error,openUserAnswer.text.blank.error.uk.co.cascaid.iebe.IebeUser.openUserAnswers.text,openUserAnswer.text.blank.error.openUserAnswers.text,openUserAnswer.text.blank.error.text,openUserAnswer.text.blank.error,uk.co.cascaid.iebe.OpenUserAnswer.text.blank.uk.co.cascaid.iebe.IebeUser.openUserAnswers.text,uk.co.cascaid.iebe.OpenUserAnswer.text.blank.openUserAnswers.text,uk.co.cascaid.iebe.OpenUserAnswer.text.blank.text,uk.co.cascaid.iebe.OpenUserAnswer.text.blank,openUserAnswer.text.blank.uk.co.cascaid.iebe.IebeUser.openUserAnswers.text,openUserAnswer.text.blank.openUserAnswers.text,openUserAnswer.text.blank.text,openUserAnswer.text.blank,blank.uk.co.cascaid.iebe.IebeUser.openUserAnswers.text,blank.openUserAnswers.text,blank.text,blank]; arguments [text,class uk.co.cascaid.iebe.OpenUserAnswer]; default message [Property [{0}] of class [{1}] cannot be blank] Field error in object 'uk.co.cascaid.iebe.IebeUser' on field 'closedUserAnswers.answer': rejected value [null]; codes [uk.co.cascaid.iebe.ClosedUserAnswer.answer.nullable.error.uk.co.cascaid.iebe.IebeUser.closedUserAnswers.answer,uk.co.cascaid.iebe.ClosedUserAnswer.answer.nullable.error.closedUserAnswers.answer,uk.co.cascaid.iebe.ClosedUserAnswer.answer.nullable.error.answer,uk.co.cascaid.iebe.ClosedUserAnswer.answer.nullable.error,closedUserAnswer.answer.nullable.error.uk.co.cascaid.iebe.IebeUser.closedUserAnswers.answer,closedUserAnswer.answer.nullable.error.closedUserAnswers.answer,closedUserAnswer.answer.nullable.error.answer,closedUserAnswer.answer.nullable.error,uk.co.cascaid.iebe.ClosedUserAnswer.answer.nullable.uk.co.cascaid.iebe.IebeUser.closedUserAnswers.answer,uk.co.cascaid.iebe.ClosedUserAnswer.answer.nullable.closedUserAnswers.answer,uk.co.cascaid.iebe.ClosedUserAnswer.answer.nullable.answer,uk.co.cascaid.iebe.ClosedUserAnswer.answer.nullable,closedUserAnswer.answer.nullable.uk.co.cascaid.iebe.IebeUser.closedUserAnswers.answer,closedUserAnswer.answer.nullable.closedUserAnswers.answer,closedUserAnswer.answer.nullable.answer,closedUserAnswer.answer.nullable,nullable.uk.co.cascaid.iebe.IebeUser.closedUserAnswers.answer,nullable.closedUserAnswers.answer,nullable.answer,nullable]; arguments [answer,class uk.co.cascaid.iebe.ClosedUserAnswer]; default message [Property [{0}] of class [{1}] cannot be null]

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• Podcast Show Notes: Evolving Enterprise Architecture

  - by Bob Rhubart

  The latest series of ArchBeat podcast programs grew out of another virtual meet-up, held on March 11. As with previous meet-ups, I sent out a general invitation to the roster of previous ArchBeat panelists to join me on Skype to talk about whatever topic comes up. For this event, Oracle ACE Directors Mike van Alst and Jordan Braunstein  showed up, along with Oracle product manager Jeff Davies.  The result was an impressive and wide-ranging discussion on the evolution of Enterprise Architecture, the role of technology in EA, the impact of social computing, and challenge of having three generations of IT people at work in the enterprise – each with different perspectives on technology. Mike, Jordan, and Jeff talked for more than an hour, and the conversation was so good that slicing and dicing it to meet the time constraints for these podcasts has been a challenge. The first two segments of the conversation are now available. Listen to Part 1 Listen to Part 2 Part 3 will go live next week, and an unprecedented fourth segment will follow. These guys have strong opinions, and while there is common ground, they don’t always agree. But isn’t that what a community is all about? I suspect that you’ll have questions and comments after listening, so I encourage you to reach out to Mike, Jordan, and Jeff  via the following links: Mike van Alst Blog | Twitter | LinkedIn | Business |Oracle Mix | Oracle ACE Profile Jordan Braunstein Blog | Twitter | LinkedIn | Business | Oracle Mix | Oracle ACE Profile Jeff Davies Homepage | Blog | LinkedIn | Oracle Mix (Also check out Jeff’s book: The Definitive Guide to SOA: Oracle Service Bus)   Coming Soon ArchBeat’s microphones were there for the panel discussions at the recent Oracle Technology Network Architect Days in Dallas and Anaheim. Excerpts from those conversations will be available soon. Stay tuned: RSS Technorati Tags: oracle,otn,enterprise architecture,podcast. arch2arch,archbeat del.icio.us Tags: oracle,otn,enterprise architecture,podcast. arch2arch,archbeat

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• Would you re-design completely under .Net?

  - by dboarman

  A very extensive application began as an Access-based system (for database storage). Forms were written in VB5 and/or VB6. As .Net became a fixture in the development community, certain modules have been rewritten. This seems very awkward and potentially costly just to maintain because of the cross-technologies and extra work to keep the two technologies happy with each other. Of course, the application uses a mix of ODBC OleDb and MySql. Would you think spending the time and resources to completely re-develop the application under .Net would be more cost effective? In an effort to develop a more stable application, wouldn't it make sense to use .Net? Or continue chasing Access bugs, adding new features in .Net (which may or may not create new bugs between .Net and Access), and rewriting old Access modules into .Net modules under time constraints that prevent proper design and development? Update The application uses OleDb and MySql - I corrected my previous statement. Also, to lend further support to rewriting: I have since found out that when the "porting" to .Net began, the VBA/VB6 code that existed was basically translated to the .Net equivalent. From my understanding, nothing was done to improve performance, or take advantage of new libraries or technologies. In my opinion, this creates a very fragile and unstable application. With every new update, this becomes more and more visible. As a help desk technician, I have noticed an increase in problems reported. The customers using the software have noticed an increase in problems and are commenting on it.

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• TOTD #166: Using NoSQL database in your Java EE 6 Applications on GlassFish - MongoDB for now!

  - by arungupta

  The Java EE 6 platform includes Java Persistence API to work with RDBMS. The JPA specification defines a comprehensive API that includes, but not restricted to, how a database table can be mapped to a POJO and vice versa, provides mechanisms how a PersistenceContext can be injected in a @Stateless bean and then be used for performing different operations on the database table and write typesafe queries. There are several well known advantages of RDBMS but the NoSQL movement has gained traction over past couple of years. The NoSQL databases are not intended to be a replacement for the mainstream RDBMS. As Philosophy of NoSQL explains, NoSQL database was designed for casual use where all the features typically provided by an RDBMS are not required. The name "NoSQL" is more of a category of databases that is more known for what it is not rather than what it is. The basic principles of NoSQL database are: No need to have a pre-defined schema and that makes them a schema-less database. Addition of new properties to existing objects is easy and does not require ALTER TABLE. The unstructured data gives flexibility to change the format of data any time without downtime or reduced service levels. Also there are no joins happening on the server because there is no structure and thus no relation between them. Scalability and performance is more important than the entire set of functionality typically provided by an RDBMS. This set of databases provide eventual consistency and/or transactions restricted to single items but more focus on CRUD. Not be restricted to SQL to access the information stored in the backing database. Designed to scale-out (horizontal) instead of scale-up (vertical). This is important knowing that databases, and everything else as well, is moving into the cloud. RBDMS can scale-out using sharding but requires complex management and not for the faint of heart. Unlike RBDMS which require a separate caching tier, most of the NoSQL databases comes with integrated caching. Designed for less management and simpler data models lead to lower administration as well. There are primarily three types of NoSQL databases: Key-Value stores (e.g. Cassandra and Riak) Document databases (MongoDB or CouchDB) Graph databases (Neo4J) You may think NoSQL is panacea but as I mentioned above they are not meant to replace the mainstream databases and here is why: RDBMS have been around for many years, very stable, and functionally rich. This is something CIOs and CTOs can bet their money on without much worry. There is a reason 98% of Fortune 100 companies run Oracle :-) NoSQL is cutting edge, brings excitement to developers, but enterprises are cautious about them. Commercial databases like Oracle are well supported by the backing enterprises in terms of providing support resources on a global scale. There is a full ecosystem built around these commercial databases providing training, performance tuning, architecture guidance, and everything else. NoSQL is fairly new and typically backed by a single company not able to meet the scale of these big enterprises. NoSQL databases are good for CRUDing operations but business intelligence is extremely important for enterprises to stay competitive. RDBMS provide extensive tooling to generate this data but that was not the original intention of NoSQL databases and is lacking in that area. Generating any meaningful information other than CRUDing require extensive programming. Not suited for complex transactions such as banking systems or other highly transactional applications requiring 2-phase commit. SQL cannot be used with NoSQL databases and writing simple queries can be involving. Enough talking, lets take a look at some code. This blog has published multiple blogs on how to access a RDBMS using JPA in a Java EE 6 application. This Tip Of The Day (TOTD) will show you can use MongoDB (a document-oriented database) with a typical 3-tier Java EE 6 application. Lets get started! The complete source code of this project can be downloaded here. Download MongoDB for your platform from here (1.8.2 as of this writing) and start the server as: arun@ArunUbuntu:~/tools/mongodb-linux-x86_64-1.8.2/bin$./mongod./mongod --help for help and startup optionsSun Jun 26 20:41:11 [initandlisten] MongoDB starting : pid=11210port=27017 dbpath=/data/db/ 64-bit Sun Jun 26 20:41:11 [initandlisten] db version v1.8.2, pdfile version4.5Sun Jun 26 20:41:11 [initandlisten] git version:433bbaa14aaba6860da15bd4de8edf600f56501bSun Jun 26 20:41:11 [initandlisten] build sys info: Linuxbs-linux64.10gen.cc 2.6.21.7-2.ec2.v1.2.fc8xen #1 SMP Fri Nov 2017:48:28 EST 2009 x86_64 BOOST_LIB_VERSION=1_41Sun Jun 26 20:41:11 [initandlisten] waiting for connections on port 27017Sun Jun 26 20:41:11 [websvr] web admin interface listening on port 28017 The default directory for the database is /data/db and needs to be created as: sudo mkdir -p /data/db/sudo chown `id -u` /data/db You can specify a different directory using "--dbpath" option. Refer to Quickstart for your specific platform. Using NetBeans, create a Java EE 6 project and make sure to enable CDI and add JavaServer Faces framework. Download MongoDB Java Driver (2.6.3 of this writing) and add it to the project library by selecting "Properties", "LIbraries", "Add Library...", creating a new library by specifying the location of the JAR file, and adding the library to the created project. Edit the generated "index.xhtml" such that it looks like: <h1>Add a new movie</h1><h:form> Name: <h:inputText value="#{movie.name}" size="20"/><br/> Year: <h:inputText value="#{movie.year}" size="6"/><br/> Language: <h:inputText value="#{movie.language}" size="20"/><br/> <h:commandButton actionListener="#{movieSessionBean.createMovie}" action="show" title="Add" value="submit"/></h:form> This page has a simple HTML form with three text boxes and a submit button. The text boxes take name, year, and language of a movie and the submit button invokes the "createMovie" method of "movieSessionBean" and then render "show.xhtml". Create "show.xhtml" ("New" -> "Other..." -> "Other" -> "XHTML File") such that it looks like: <head> <title><h1>List of movies</h1></title> </head> <body> <h:form> <h:dataTable value="#{movieSessionBean.movies}" var="m" > <h:column><f:facet name="header">Name</f:facet>#{m.name}</h:column> <h:column><f:facet name="header">Year</f:facet>#{m.year}</h:column> <h:column><f:facet name="header">Language</f:facet>#{m.language}</h:column> </h:dataTable> </h:form> This page shows the name, year, and language of all movies stored in the database so far. The list of movies is returned by "movieSessionBean.movies" property. Now create the "Movie" class such that it looks like: import com.mongodb.BasicDBObject;import com.mongodb.BasicDBObject;import com.mongodb.DBObject;import javax.enterprise.inject.Model;import javax.validation.constraints.Size;/** * @author arun */@Modelpublic class Movie { @Size(min=1, max=20) private String name; @Size(min=1, max=20) private String language; private int year; // getters and setters for "name", "year", "language" public BasicDBObject toDBObject() { BasicDBObject doc = new BasicDBObject(); doc.put("name", name); doc.put("year", year); doc.put("language", language); return doc; } public static Movie fromDBObject(DBObject doc) { Movie m = new Movie(); m.name = (String)doc.get("name"); m.year = (int)doc.get("year"); m.language = (String)doc.get("language"); return m; } @Override public String toString() { return name + ", " + year + ", " + language; }} Other than the usual boilerplate code, the key methods here are "toDBObject" and "fromDBObject". These methods provide a conversion from "Movie" -> "DBObject" and vice versa. The "DBObject" is a MongoDB class that comes as part of the mongo-2.6.3.jar file and which we added to our project earlier.  The complete javadoc for 2.6.3 can be seen here. Notice, this class also uses Bean Validation constraints and will be honored by the JSF layer. Finally, create "MovieSessionBean" stateless EJB with all the business logic such that it looks like: package org.glassfish.samples;import com.mongodb.BasicDBObject;import com.mongodb.DB;import com.mongodb.DBCollection;import com.mongodb.DBCursor;import com.mongodb.DBObject;import com.mongodb.Mongo;import java.net.UnknownHostException;import java.util.ArrayList;import java.util.List;import javax.annotation.PostConstruct;import javax.ejb.Stateless;import javax.inject.Inject;import javax.inject.Named;/** * @author arun */@Stateless@Namedpublic class MovieSessionBean { @Inject Movie movie; DBCollection movieColl; @PostConstruct private void initDB() throws UnknownHostException { Mongo m = new Mongo(); DB db = m.getDB("movieDB"); movieColl = db.getCollection("movies"); if (movieColl == null) { movieColl = db.createCollection("movies", null); } } public void createMovie() { BasicDBObject doc = movie.toDBObject(); movieColl.insert(doc); } public List<Movie> getMovies() { List<Movie> movies = new ArrayList(); DBCursor cur = movieColl.find(); System.out.println("getMovies: Found " + cur.size() + " movie(s)"); for (DBObject dbo : cur.toArray()) { movies.add(Movie.fromDBObject(dbo)); } return movies; }} The database is initialized in @PostConstruct. Instead of a working with a database table, NoSQL databases work with a schema-less document. The "Movie" class is the document in our case and stored in the collection "movies". The collection allows us to perform query functions on all movies. The "getMovies" method invokes "find" method on the collection which is equivalent to the SQL query "select * from movies" and then returns a List<Movie>. Also notice that there is no "persistence.xml" in the project. Right-click and run the project to see the output as: Enter some values in the text box and click on enter to see the result as: If you reached here then you've successfully used MongoDB in your Java EE 6 application, congratulations! Some food for thought and further play ... SQL to MongoDB mapping shows mapping between traditional SQL -> Mongo query language. Tutorial shows fun things you can do with MongoDB. Try the interactive online shell  The cookbook provides common ways of using MongoDB In terms of this project, here are some tasks that can be tried: Encapsulate database management in a JPA persistence provider. Is it even worth it because the capabilities are going to be very different ? MongoDB uses "BSonObject" class for JSON representation, add @XmlRootElement on a POJO and how a compatible JSON representation can be generated. This will make the fromXXX and toXXX methods redundant.

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