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• Incoming connections from 2 different Internet connections

  - by RJClinton

  I am hosting a Gameserver on my Windows 2003 Server 32 Bit Server. Due to some limitations of my ISP, I have to take 2 Internet connections in order to satisfy my bandwidth requirement. I am facing serious problems here. The Internet is supplied using Wimax. I am given a POE and the RJ45 from both the POE (2 connections) are plugged into a Netgear 100mbps Switch and another RJ45 connects the server to the switch. I have tried to configure the IP addresses and gateway of both connections to the single NIC in the server. The IP series and the gateway of each Internet connection are very much different. I know that this is not the proper approach, because alternate gateways are meant to be only for backup in case of main gateway failure and the usage of the gateways depends upon the metric (correct me if I am wrong). I am planning to get a second PCI NIC so that I can connect each of the Internet connections into its respective NIC. If I use this approach, will I be able to accept connections on both NICs? Also, please suggest any other alternatives that I might use.

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• Is an LSA MSV1_0 subauthentication package needed for some impersonation use cases?

  - by Chris Sears

  Greetings, I'm working with a vendor who has implemented some code that uses a Windows LSA MSV1_0 subauthentication package (MSDN info if you're interested: http://msdn.microsoft.com/en-us/library/aa374786(VS.85).aspx ) and I'm trying to figure out if it's necessary. As far as I can tell, the subauthentication routine and filter allow for hooking or customizing the standard LSA MSV1_0 logon event processing. The issue is that I don't understand why the vendor's product would need these capabilities. I've asked them and they said they use it to perform impersonation. The product definitely does need to do impersonation, but based on my limited win32 knowledge, they could get the functionality they need using the normal auth APIs (LsaLogonUser, ImpersonateLoggedOnUser, etc) without the subauthentication package. Furthermore, I've worked with a number of similar products that all do impersonation, and this is the only one that's used a subauthentication package. If you're wondering why I would care, a previous version of the product had a bug in the subauthentication package dll that would cause lockups or bluescreens. That makes me rather nervous and has me questioning the use of such a low-level, kernel sensitive interface. I'd like to go back to the vendor and say "There's no way you could need an LSA subauth package for impersonation - take it out", but I'm not sure I understand the use cases and possible limitations of the standard win32 authentication/impersonation APIs well enough to make that claim definitively. So, to the win32 security gurus out there, is there any reason you would need an LSA MSV1_0 subauthentication package if all you were doing is impersonation? Thanks in advance for any thoughts!

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• Is there an "embedded DBMS" to support multiple writer applications (processes) on the same db files

  - by Amir Moghimi

  I need to know if there is any embedded DBMS (preferably in Java and not necessarily relational) which supports multiple writer applications (processes) on the same set of db files. BerkeleyDB supports multiple readers but just one writer. I need multiple writers and multiple readers. UPDATE: It is not a multiple connection issue. I mean I do not need multiple connections to a running DBMS application (process) to write data. I need multiple DBMS applications (processes) to commit on the same storage files. HSQLDB, H2, JavaDB (Derby) and MongoDB do not support this feature. I think that there may be some File System limitations that prohibit this. If so, is there a File System that allows multiple writers on a single file? Use Case: The use case is a high-throughput clustered system that intends to store its high-volume business log entries into a SAN storage. Storing business logs in separate files for each server does not fit because query and indexing capabilities are needed on the whole biz logs. Because "a SAN typically is its own network of storage devices that are generally not accessible through the regular network by regular devices", I want to use SAN network bandwidth for logging while cluster LAN bandwidth is being used for other server to server and client to server communications.

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• Rails apps blew up on mediatemple's (dv) server

  - by BandsOnABudget

  i managed to fix this issue but i wanted to document it here for any others whom might have similar problems. I'm running a mediatemple (dv) rage server. monit started sending me alerts that i was having resource limitations on the server. logged into plesk and the CPU was pinned at 99.9%. Rebooted the server, catastrophe avoided... Not quite - all my rails apps were not loading My Setup ruby 1.8.6 Rails 2.3.5 w/ passenger installed as an apache module. I noticed a defunct ruby process so i killed and rebooted the server but runby continued to come back as defunct. Started trolling thru the apache log and i saw errors irt updating rubygems. i updated to the latest but then continued to get gem errors. Basically, I had to go thru all my apps and update any gems manually, reboot apache, and all was restored. Not really sure the cause of the issue but wanted to note it for posterity. Anybody else in the community ever have similar issues???

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• Change dynamic web reference from web./app.config

  - by Snæbjørn

  I have a problem changing a dynamic web reference in the config file. Changing the url in the config file doesn't have any effect. I have to change the url in .settings and compile for it to change. I added the web reference using the wizard. Set the URL behavior to dynamic, which added the relevant XML tags in config file. In my solution I have the web API (web reference) in a separate project (class lib), so I referenced the project and copied the <applicationSettings> over. <applicationSettings> <StartupProject.Properties.Settings> <setting name="WebReference" serializeAs="String"> <value>http://someurl/somefile.asmx</value> </setting> </StartupProject.Properties.Settings> </applicationSettings> Note that it's <StartupProject.Properties.Settings> and not <WebRefProject.Properties.Settings>. Are there some limitations I'm not aware of or am I doing something wrong?

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• Managing Cisco programatically; Telnet vs SNMP?

  - by MikeHerrera

  I was recently approached by a network-engineer, co-worker who would like to offload his minor network admin duties to a junior-level helpdesk tech. The specific location in need of management acts as an ISP for tenants on its single-site property, so there's a lot of small adjustments being made on a daily basis. I am thinking it would be helpful to write him a winform app to manage the 32 Cisco devices, on-site. I'd like to initially provide functionality which could modify access control lists, port VLAN assignments, and bandwidth limitations per VLAN... adding more to the list as its deemed valuable. My initial thought was to emulate a telnet session with the network device; utilizing my network-engineer's familiarity with the command-line / IOS interaction. Minimal time would be required to learn Cisco IOS conventions, myself. Though while searching for solutions, it appears that most people favor SNMP. That, or, their specific circumstances pushed them in the direction of SNMP. I wanted to know if I've overlooked an obvious benefit of SNMP. Should I be using SNMP? Why or why not?

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• Unit testing JSON output module, best practices

  - by Banang

  I am currently working on a module that takes one of our business objects and returns a json representation of that object to the caller. Due to limitations in our environment I am unable to use any existing json writer, so I have written my own, which is then used by the business object writer to serialize my objects. The json writer is tested in a way similar to this @Test public void writeEmptyArrayTest() { String expected = "[ ]"; writer.array().endArray(); assertEquals(expected, writer.toString()); } which is only manageable because of the small output each instruction produces, even though I keep feeling there must be a better way. The problem I am now facing is writing tests for the object writer module, where the output is much larger and much less manageable. The risk of spelling mistakes in the expected strings mucking up my tests seem too great, and writing code in this fashion seems both silly and unmanageable in a long term perspective. I keep feeling like I want to write tests to ensure that my tests are behaving correctly, and this feeling worries me. Therefore, is there a better way of doing this? Surely there must be? Does anyone know of any good literature in regard to this specific case (doesn't have to be json, but you know what I mean)? Grateful for all help.

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• Mathematical annotations in a PDF file

  - by kvaruni

  I like to annotate papers I read in a digital way. Numerous programs exist to help in this process. For example, on OS X one can use programs such as Skim or even Preview. However, making annotations is dreadful when one wishes to add mathematical annotations, such as formulas or greek letters. A cumbersome "solution" is to select the desired symbol one by one using the Special Characters palette, though this considerably slows down the annotation process. Is there any way to add mathematical annotations to a PDF? The only two limitations that I would impose on a solution is that 1) the mathematical text needs to be selectable, i.e. it must be text and 2) I want to limit the number of programs I need to make the process as painless as possible. Some of the more promising solutions I have tried include generating LaTeX with LaTeXiT, but it seems to be impossible to add a PDF on top of another PDF. Another attempt was to use jsMath to generate the symbols and copy-paste these as annotation using one of the jsMath fonts. This results in unreadable, incorrect characters.

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• How do I best display CheckBoxes in SQL Server Reporting Services?

  - by Yadyn

  One of the many quirks of Reporting Services we've run across is the complete and utter lack of a CheckBox control or even something remotely similar. We have a form that should appear automatically filled out based on information pulled from a database. We have several bit datatype fields. Printing out "True" or "False" just looks silly, as this is supposed to look like a form that has been auto-filled out, so we want to have a series of checkboxes and labels that are either checked or unchecked. We are running SSRS 2005 but I'm not aware of SSRS 2008 having added a CheckBox control. Even if it did, we'd need to have an alternative for the time being. The best we've found so far is: use Wingdings use images use text boxes with borders and print a blank/space or a capital X All three approaches require IIF expression shenanigans. The Wingdings approach seemed to work acceptably, and was the most aesthetically pleasing except that for whatever reason it didn't always print correctly. More importantly, PDF exports, also for whatever reason, converted all fonts (generally) to Arial and so we got funky letters instead of the Windings dingbats. Images, being a pixel-based raster, don't do so well when printed along side vector stuff like text. Unless handled carefully, they tend to stretch, pixelate, and do other unprofessional looking things. While these methods do work (some with limitations as mentioned above) none of them are particularly elegant. Are we missing something obvious? Not so obvious? Does someone at Microsoft have a good reason why such a control was not provided in SSRS 2000, let alone 2 versions and 8 years later? This can't be the first time this issue has come up...

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• Understanding floating point problems

  - by Maxim Gershkovich

  Could someone here please help me understand how to determine when floating point limitations will cause errors in your calculations. For example the following code. CalculateTotalTax = function (TaxRate, TaxFreePrice) { return ((parseFloat(TaxFreePrice) / 100) * parseFloat(TaxRate)).toFixed(4); }; I have been unable to input any two values that have caused for me an incorrect result for this method. If I remove the toFixed(4) I can infact see where the calculations start to lose accuracy (somewhere around the 6th decimal place). Having said that though, my understanding of floats is that even small numbers can sometimes fail to be represented or have I misunderstood and can 4 decimal places (for example) always be represented accurately. MSDN explains floats as such... This means they cannot hold an exact representation of any quantity that is not a binary fraction (of the form k / (2 ^ n) where k and n are integers) Now I assume this applies to all floats (inlcuding those used in javascript). Fundamentally my question boils down to this. How can one determine if any specific method will be vulnerable to errors in floating point operations, at what precision will those errors materialize and what inputs will be required to produce those errors? Hopefully what I am asking makes sense.

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• SQLDeveloper using over 100MB of PGA

  - by Leigh Riffel

  Perhaps this is normal, but in my Oracle 11g database I am seeing programmers using Oracle's SQL Developer regularly consume more than 100MB of combined UGA and PGA memory. I'd like to know if this is normal and what can be done about it. Our database is on the 32 bit version of Windows 2008, so memory limitations are becoming an increasing concern. I am using the following query to show the memory usage: SELECT e.SID, e.username, e.status, b.PGA_MEMORY FROM v$session e LEFT JOIN (select y.SID, y.value pga, TO_CHAR(ROUND(y.value/1024/1024),99999999) || ' MB' PGA_MEMORY from v$sesstat y, v$statname z where y.STATISTIC# = z.STATISTIC# and NAME = 'session pga memory') b ON e.sid=b.sid WHERE (PGA)/1024/1024 > 20 ORDER BY 4 DESC; It seems that the resource usage goes up any time a table is opened in SQLDeveloper, but even when it is closed the memory does not go away. The problem is worse if the table is sorted while it was open as that seems to use even more memory. I understand how this would use memory while it is sorting, and perhaps even while it is still open, but to use memory after it is closed seems wrong to me. Can anyone confirm this? Update: I discovered that my numbers were off due to not understanding that the UGA is stored in the PGA under dedicated server mode. This makes the numbers lower than they were, but the problem still remains that SQL Developer seems to use excessive PGA.

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• Asynchronous background processes in Python?

  - by Geuis

  I have been using this as a reference, but not able to accomplish exactly what I need: http://stackoverflow.com/questions/89228/how-to-call-external-command-in-python/92395#92395 I also was reading this: http://www.python.org/dev/peps/pep-3145/ For our project, we have 5 svn checkouts that need to update before we can deploy our application. In my dev environment, where speedy deployments are a bit more important for productivity than a production deployment, I have been working on speeding up the process. I have a bash script that has been working decently but has some limitations. I fire up multiple 'svn updates' with the following bash command: (svn update /repo1) & (svn update /repo2) & (svn update /repo3) & These all run in parallel and it works pretty well. I also use this pattern in the rest of the build script for firing off each ant build, then moving the wars to Tomcat. However, I have no control over stopping deployment if one of the updates or a build fails. I'm re-writing my bash script with Python so I have more control over branches and the deployment process. I am using subprocess.call() to fire off the 'svn update /repo' commands, but each one is acting sequentially. I try '(svn update /repo) &' and those all fire off, but the result code returns immediately. So I have no way to determine if a particular command fails or not in the asynchronous mode. import subprocess subprocess.call( 'svn update /repo1', shell=True ) subprocess.call( 'svn update /repo2', shell=True ) subprocess.call( 'svn update /repo3', shell=True ) I'd love to find a way to have Python fire off each Unix command, and if any of the calls fails at any time the entire script stops.

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• WF performance with new 20,000 persisted workflow instances each month

  - by Nikola Stjelja

  Windows Workflow Foundation has a problem that is slow when doing WF instances persistace. I'm planning to do a project whose bussiness layer will be based on WF exposed WCF services. The project will have 20,000 new workflow instances created each month, each instance could take up to 2 months to finish. What I was lead to belive that given WF slownes when doing peristance my given problem would be unattainable given performance reasons. I have the following questions: Is this true? Will my performance be crap with that load(given WF persitance speed limitations) How can I solve the problem? We currently have two possible solutions: 1. Each new buisiness process request(e.g. Give me a new drivers license) will be a new WF instance, and the number of persistance operations will be limited by forwarding all status request operations to saved state values in a separate database. 2. Have only a small amount of Workflow Instances up at any give time, without any persistance ofso ever(only in case of system crashes etc.), by breaking each workflow stap in to a separate worklof and that workflow handling each business process request instance in the system that is at that current step(e.g. I'm submitting my driver license reques form, which is step one... we have 100 cases of that, and my step one workflow will handle every case simultaneusly). I'm very insterested in solution for that problem. If you want to discuss that problem pleas be free to mail me at [email protected]

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• Where to find algorithms for standard math functions?

  - by dsimcha

  I'm looking to submit a patch to the D programming language standard library that will allow much of std.math to be evaluated at compile time using the compile-time function evaluation facilities of the language. Compile-time function evaluation has several limitations, the most important ones being: You can't use assembly language. You can't call C code or code for which the source is otherwise unavailable. Several std.math functions violate these and compile-time versions need to be written. Where can I get information on good algorithms for computing things such as logarithms, exponents, powers, and trig functions? I prefer just high level descriptions of algorithms to actual code, for two reasons: To avoid legal ambiguity and the need to make my code look "different enough" from the source to make sure I own the copyright. I want simple, portable algorithms. I don't care about micro-optimization as long as they're at least asymptotically efficient. Edit: D's compile time function evaluation model allows floating point results computed at compile time to differ from those computed at runtime anyhow, so I don't care if my compile-time algorithms don't give exactly the same result as the runtime version as long as they aren't less accurate to a practically significant extent.

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• Anything speaking against the bitnami.org Ruby/Rails/Redmine Stack?

  - by Pekka

  I am looking to set up a Redmine server on a Windows virtual machine on my local workstation. (Background in this related question.) I have zero knowledge of Ruby nor Rails, and while Redmine may be the opportunity to dip into those platforms somewhat, my first goal is to get it running as quickly and easily as possible. For that, I am eyeing the Bitnami Redmine Package. It promises point-and-click install, and a self-contained environment with everything you need. Apart from the learning factor, are there any serious limitations this method implies? Any serious cutdowns in customizability? I will be wanting to customize the template right away, for example, and install plugins. The package looks o.k. to me but before I install it, I was curious to know whether anybody would advise against it and why. Edit: The first impression is great. From 0 to a working Redmine installation in twelve minutes! Wow.

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• .NET XML serialization

  - by ShdNx

  I would like to serialize and deserialize mixed data into XML. After some searches I found out that there were two ways of doing it: System.Runtime.Serialization.Formatters.Soap.SoapFormatter and System.Xml.Serialization.XmlSerializer. However, neither turned out to match my requirements, since: SoapFormatter doesn't support serialization of generic types XmlSerializer refuses to serialize types that implement IDictionary, not to mention that it's far less easy-to-use than "normal" serialization (e.g. see this SO question) I'm wondering if there exists an implementation that doesn't have these limitations? I have found attempts (for example CustomXmlSerializer and YAXLib as suggested in a related SO question), but they don't seem to work either. I was thinking about writing such serializer myself (though it certainly doesn't seem to be a very easy task), but then I find myself limited by the CLR, as I cannot create object instances of types that won't have a paramaterless constructor, even if I'm using reflection. I recall having read somewhere that implementations in System.Runtime.Serialization somehow bypass the normal object creation mechanism when deserializing objects, though I'm not sure. Any hints of how could this be done? Could somebody please point me to the right direction with this?

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• GRAPH PROBLEM: find an algorithm to determine the shortest path from one point to another in a recta

  - by newba

  I'm getting such an headache trying to elaborate an appropriate algorithm to go from a START position to a EXIT position in a maze. For what is worth, the maze is rectangular, maxsize 500x500 and, in theory, is resolvable by DFS with some branch and bound techniques ... 10 3 4 7 6 3 3 1 2 2 1 0 2 2 2 4 2 2 5 2 2 1 3 0 2 2 2 2 1 3 3 4 2 3 4 4 3 1 1 3 1 2 2 4 2 2 1 Output: 5 1 4 2 Explanation: Our agent looses energy every time he gives a step and he can only move UP, DOWN, LEFT and RIGHT. Also, if the agent arrives with a remaining energy of zero or less, he dies, so we print something like "Impossible". So, in the input 10 is the initial agent's energy, 3 4 is the START position (i.e. column 3, line 4) and we have a maze 7x6. Think this as a kind of labyrinth, in which I want to find the exit that gives the agent a better remaining energy (shortest path). In case there are paths which lead to the same remaining energy, we choose the one which has the small number of steps, of course. I need to know if a DFS to a maze 500x500 in the worst case is feasible with these limitations and how to do it, storing the remaining energy in each step and the number of steps taken so far. The output means the agent arrived with remaining energy= 5 to the exit pos 1 4 in 2 steps. If we look carefully, in this maze it's also possible to exit at pos 3 1 (column 3, row 1) with the same energy but with 3 steps, so we choose the better one. With these in mind, can someone help me some code or pseudo-code? I have troubles working this around with a 2D array and how to store the remaining energy, the path (or number of steps taken)....

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• Explaining verity index and document search limits

  - by Ahmad

  As present, we currently have a CF8 standard edition server which have some limitations around verity indexing. According to Adobe Verity Server has the following document search limits (limits are for all collections registered to Verity Server): - 10,000 documents for ColdFusion Developer Edition - 125,000 documents for ColdFusion Standard Edition - 250,000 documents for ColdFusion Enterprise Edition We have now reached a stage where the server wide number of documents indexed exceed 125k. However, the largest verity collection consists of about 25k documents(and this is expected to grow). Only one collection is ever searched at a time. In my understanding, this means that I can still search an entire collection with no restrictions. Is this correct? Or does it mean that only documents that were indexed across all collection prior to reaching the limit are actually searchable? We are considering moving to CF9 standard as a solution to this and to use the Solr solution which has no restrictions. The coldfusionjedi highlights some differences between Verity and Solr. However, before we upgrade I am trying to gain a clearer understanding of this before we commit to an upgrade. Can someone provide me a clear explanation as to what this means and how it actually affects verity searching and indexing?

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• JLabel not greyed out when disabled, when HTML text displayed

  - by bguiz

  How do I get a JLabel displaying a HTML string to appear greyed out (which is the behaviour of JLabels that don't display HTML text)? Is there another way than actually changing the colour myself by modifying the foreground property? JLabel label1 = new JLabel("Normal text"); JLabel label2 = new JLabel("<html>HTML <b>text</b>"); // Both labels are now black in colour label1.setEnabled(false); label2.setEnabled(false); // label1 is greyed out, label2 is still black in colour Thank you very much for all of your responses. From what I gather, it seems that Java doesn't support automatic greying out of JLabels when they use HTML text. Suraj's solution has come closest to the fix considering the limitations. I have however, tried a different out-of-the box approach, where I have put the HTML text JLabels inside of an inner JPanel and did this: mInnerPanel.setEnabled(shouldShow); //shouldShow is a boolean value Which hasn't worked. Any suggestions for this way? EDIT: Added implemented solution.

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• Bundle a Python app as a single file to support add-ons or extensions?

  - by Brandon Craig Rhodes

  There are several utilities — all with different procedures, limitations, and target operating systems — for getting a Python package and all of its dependencies and turning them into a single binary program that is easy to ship to customers: http://wiki.python.org/moin/Freeze http://www.pyinstaller.org/ http://www.py2exe.org/ http://svn.pythonmac.org/py2app/py2app/trunk/doc/index.html My situation goes one step further: third-party developers will be wanting to write plug-ins, extensions, or add-ons for my application. It is, of course, a daunting question how users on platforms like Windows would most easily install plugins or addons in such a way that my app can easily discover that they have been installed. But beyond that basic question is another: how can a third-party developer bundle their extension with whatever libraries the extension itself needs (which might be binary modules, like lxml) in such a way that the plugin's dependencies become available for import at the same time that the plugin becomes available. How can this be approached? Will my application need its own plug-in area on disk and its own plug-in registry to make this tractable? Or are there general mechanisms, that I could avoid writing myself, that would allow an app that is distributed as a single executable to look around and find plugins that are also installed as single files?

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• Customising Flex Datagrid or alternative solutions

  - by Martin

  I'm currently building an application that is presenting tabular (fetched from a webservice) data and have squirted it into a datagrid - seemed the most obvious way to present it on screen. I've now come across a few limitations in the datagrid and wonder how I might move forward. As a relative newcomer to flex development I'm a little lost. A few things I am wanting to do. The data is logically split into groups and I would like to be able to have subheadings in the grid whenever I move to a new group. I would like to be able to highligh individual cells based on their content relative to other values in the row - ie highlight the cell with the highest value in the row. Is this possible with the standard datagrid? I'm actually using the try-before-you-buy version of flex builder at the moment but I have ordered Flex Builder 3 Pro - which is on its way to me. I understand there is an 'advanced datagrid' control in this version - perhaps that will support some of what I wish to do? Alternatively - is there another way of building custom tabular data?

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• New to web development - backend questions

  - by James

  I'm new to web development although I'm confident in the roadmap for the front-end. I need direction on two things: Basic architecture Back-end technologies For architecture, what do I need to get started? From what I know, its: Get a domain name registered (godaddy?) Find a web host ??? anything else? or start developing the site? I don't think its that easy, there must be something I'm missing, right? For the back-end technologies, I have application development experience with Java and Python, but how likely is it to find a back-end hosting site that supports these languages over PHP? Is PHP a better choice? If I stick with what I know for the back-end, am I sabotaging myself later on? If I need help, how is the market for a python/java developer vs. a php developer? What do I need to know about databases? I have some basic SQL experience. Do hosting sites have limitations on the type of databases or bandwidth I need to worry about? I'm working through some of the common sites: StackOverflow, Sitepoint forums, Google, etc...are there other resources I should use?

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• PostgreSQL insert on primary key failing with contention, even at serializable level

  - by Steven Schlansker

  I'm trying to insert or update data in a PostgreSQL db. The simplest case is a key-value pairing (the actual data is more complicated, but this is the smallest clear example) When you set a value, I'd like it to insert if the key is not there, otherwise update. Sadly Postgres does not have an insert or update statement, so I have to emulate it myself. I've been working with the idea of basically SELECTing whether the key exists, and then running the appropriate INSERT or UPDATE. Now clearly this needs to be be in a transaction or all manner of bad things could happen. However, this is not working exactly how I'd like it to - I understand that there are limitations to serializable transactions, but I'm not sure how to work around this one. Here's the situation - ab: => set transaction isolation level serializable; a: => select count(1) from table where id=1; --> 0 b: => select count(1) from table where id=1; --> 0 a: => insert into table values(1); --> 1 b: => insert into table values(1); --> ERROR: duplicate key value violates unique constraint "serial_test_pkey" Now I would expect it to throw the usual "couldn't commit due to concurrent update" but I'm guessing since the inserts are different "rows" this does not happen. Is there an easy way to work around this?

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• Working with mongodb from Java

  - by demas

  I have launch mongodb server: [[email protected]][~]% mongod --dbpatmongod --dbpath /home/demas/temp/ Mon Apr 19 09:44:18 Mongo DB : starting : pid = 4538 port = 27017 dbpath = /home/demas/temp/ master = 0 slave = 0 32-bit ** NOTE: when using MongoDB 32 bit, you are limited to about 2 gigabytes of data ** see http://blog.mongodb.org/post/137788967/32-bit-limitations for more Mon Apr 19 09:44:18 db version v1.4.0, pdfile version 4.5 Mon Apr 19 09:44:18 git version: nogitversion Mon Apr 19 09:44:18 sys info: Linux arch.local.net 2.6.33-ARCH #1 SMP PREEMPT Mon Apr 5 05:57:38 UTC 2010 i686 BOOST_LIB_VERSION=1_41 Mon Apr 19 09:44:18 waiting for connections on port 27017 Mon Apr 19 09:44:18 web admin interface listening on port 28017 I have created documents by console client: [[email protected]][~]% mongo MongoDB shell version: 1.4.0 url: test connecting to: test type "help" for help > db.some.find(); { "_id" : ObjectId("4bcbef3c3be43e9b7e04ef3d"), "name" : "mongo" } { "_id" : ObjectId("4bcbef423be43e9b7e04ef3e"), "x" : 3 } Now I am trying to work with MongoDb from Java: import com.mongodb.*; import java.net.UnknownHostException; public class test1 { public static void main(String[] args) { System.out.println("Start"); try { Mongo m = new Mongo("localhost", 27017); DB db = m.getDB("test"); DBCollection coll = db.getCollection("some"); coll.insert(makeDocument(10, "James", "male")); System.out.println("Finish"); } catch (UnknownHostException ex) { ex.printStackTrace(); } catch (MongoException ex) { ex.printStackTrace(); } } public static BasicDBObject makeDocument(int id, String name, String gender) { BasicDBObject doc = new BasicDBObject(); doc.put("id", id); doc.put("name", name); doc.put("gender", gender); return doc; } } But execution stops on line coll.insert(): [[email protected]][~/dev/study/java/mongodb]% javac test1.java [[email protected]][~/dev/study/java/mongodb]% java test1 Start There are not messages from mogodb server regarding accepted connection. Why?

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• Hybrid EAV/CR model via WCF (and statically-typed language)?

  - by Pat

  Background I'm working on the architecture for a cloud-based LOB application, using Silverlight for the client, WCF, ASP.NET/C# for server and SQL Server for storage. The data model requires some flexibility per user (ability to add custom properties and define validation rules for them, for example), and a hybrid EAV/CR persistence model on the server side will suit nicely. Problem I need an efficient and maintainable technology and approach to handle the transformation from the persisted EAV model to/from WCF (and similarly allow the client to bind to the resulting data - DataGrid is a key UI element)? Admission: I don't yet know enough about WCF to understand if it supports ExpandoObject directly, but I suspect it will. Options I started off looking at WCF RIA services, but quickly discovered they're heavily dependent upon both static type data and compile-time code generation. Neither of these appeal. The options I'm considering include: Using WCF RIA services and pass the data over the network directly in EAV form (i.e. Dictionary), and handle the binding issue purely on the client side (like this) Using a dynamic language (probably IronPython) to handle both ends of the communication, with plumbing to generate the necessary CLR type data on the client to allow binding, and transform to/from EAV form on the server (spam preventer stopped me from posting a URL here, I'll try it in a comment). Dynamic LINQ (CreateClass() and friends), although I'm way out of my depth there and don't know what the limitations on that approach might be yet. I'm interested in comments on these approaches as well as alternative approaches that might solve the problem. Other Notes The Silverlight client will not be the only consumer of the service, making me slightly uncomfortable with option #1 above. While the data model is flexible, it's not expected to be modified heavily. For argument's sake, we could assume that we might have 25 distinct data models active at a given time, with something like 10-20 unique data fields/rules each. Modifications to the data model will happen infrequently (typically when a new user is initially configured).

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