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  • searching for a programming platform with hot code swap

    - by Andreas
    I'm currently brainstorming over the idea how to upgrade a program while it is running. (Not while debugging, a "production" system.) But one thing that is required for it, is to actually submit the changed source code or compiled byte code into the running process. Pseudo Code var method = typeof(MyClass).GetMethod("Method1"); var content = //get it from a database (bytecode or source code) SELECT content FROM methods WHERE id=? AND version=? method.SetContent(content); At first, I want to achieve the system to work without the complexity of object-orientation. That leads to the following requirements: change source code or byte code of function drop functions add new functions change the signature of a function With .NET (and others) I could inject a class via an IoC and could thus change the source code. But the loading would be cumbersome, because everything has to be in an Assembly or created via Emit. Maybe with Java this would be easier? The whole ClassLoader is replacable, I think. With JavaScript I could achieve many of the goals. Simply eval a new function (MyMethod_V25) and assign it to MyClass.prototype.MyMethod. I think one can also drop functions somehow with "del" Which general-purpose platform can handle such things?

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  • Strange File Upload issue with asp.net site on a web farm

    - by Coov
    I have a basic asp.net file upload page. When I test file uploads from my local machine, it works fine. When I test file uploads from our dev machine, it works fine. When I deploy the site to our production webfarm, it behaves strangely. If I access the site from off the network, I can load file-after-file without issue. If I access the site from within our network, I can load the first file just fine but any subsequent files result it a bad sequence of commands error. I'm not sure if this is web farm issue, a network issue, or something else. It feels like a connection is not being disposed of properly but it doesn't make sense why everything works fine remotely. Markup: <asp:FileUpload ID="FileUpload1" runat="server" Width="350px" /> <asp:Button ID="btnSubmit" runat="server" Text="Upload" onclick="btnSubmit_Click" /> Code: if (FileUpload1.HasFile) { FtpWebRequest ftpRequest; FtpWebResponse ftpResponse; ftpRequest = (FtpWebRequest)FtpWebRequest.Create(new Uri("ftp://ftp.myftpsite.com/" + FileUpload1.FileName)); ftpRequest.Method = WebRequestMethods.Ftp.UploadFile; ftpRequest.Proxy = null; ftpRequest.UseBinary = true; ftpRequest.Credentials = new NetworkCredential("username", "password"); ftpRequest.KeepAlive = false; byte[] fileContents = new byte[FileUpload1.PostedFile.ContentLength]; using (Stream fr = FileUpload1.PostedFile.InputStream) { fr.Read(fileContents, 0, FileUpload1.PostedFile.ContentLength); } using (Stream writer = ftpRequest.GetRequestStream()) { writer.Write(fileContents, 0, fileContents.Length); } ftpResponse = (FtpWebResponse)ftpRequest.GetResponse(); Response.Write(ftpResponse.StatusDescription); }

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  • Looking for a good dev environment for OSGi bundles

    - by Riduidel
    Hi, I'm currently investigating in the field of dev environment for OSGi bundles. My goal is to find a way to develop, test and debug with ease the bundles I'll be coding. Besides, I have some "cultural" requirements. I want to be able to use java continuous integration servers (typically, Hudson) As a consequence of that first requirement, I want to have a repeatable, one-click build process. My typical tool for that is maven. And finally, being long-term Eclipse user, and having the m2eclipse at hand to merge my eclipse env with my maven one, I obviously want to be able to test and debug with that IDE. So far, here are the infos I know I can use (and have already tested) maven-bundle-plugin, maven-ipojo-plugin which both offer clean packaging facilities I have tested maven pax (and eclipse pax) and am not really satisfied with both : maven pax generates a very heavy project, where adding dependencies is very error-prone (the maven pax:import-bundle command line, with all its arguments, is a hell per se) I have taken a look at Karaf, which seems to have some nice direct maven provisionning, but I don't know how to integrate it with my Eclipse, besides using the traditionnal JPDA bridge. However, it seems to be more production-oriented than dev-oriented, and as such may require heavy configuration to fit my need (although the reading of its user manual doesn't revedal that). Have you got any ideas ? Some maven/eclipse plugins ?

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  • Testing a patch to the Rails mysql adapter

    - by Sleepycat
    I wrote a little monkeypatch to the Rails MySQLAdapter and want to package it up to use it in my other projects. I am trying to write some tests for it but I am still new to testing and I am not sure how to test this. Can someone help get me started? Here is the code I want to test: unless RAILS_ENV == 'production' module ActiveRecord module ConnectionAdapters class MysqlAdapter < AbstractAdapter def select_with_explain(sql, name = nil) explanation = execute_with_disable_logging('EXPLAIN ' + sql) e = explanation.all_hashes.first exp = e.collect{|k,v| " | #{k}: #{v} "}.join log(exp, 'Explain') select_without_explain(sql, name) end def execute_with_disable_logging(sql, name = nil) #:nodoc: #Run a query without logging @connection.query(sql) rescue ActiveRecord::StatementInvalid => exception if exception.message.split(":").first =~ /Packets out of order/ raise ActiveRecord::StatementInvalid, "'Packets out of order' error was received from the database. Please update your mysql bindings (gem install mysql) and read http://dev.mysql.com/doc/mysql/en/password-hashing.html for more information. If you're on Windows, use the Instant Rails installer to get the updated mysql bindings." else raise end end alias_method_chain :select, :explain end end end end Thanks.

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  • mySQL Efficiency Issue - How to find the right balance of normalization...?

    - by Foo
    I'm fairly new to working with relational databases, but have read a few books and know the basics of good design. I'm facing a design decision, and I'm not sure how to continue. Here's a very over simplified version of what I'm building: People can rate photos 1-5, and I need to display the average votes on the picture while keeping track of the individual votes. For example, 12 people voted 1, 7 people voted 2, etc. etc. The normalization freak of me initially designed the table structure like this: Table pictures id* | picture | userID | Table ratings id* | pictureID | userID | rating With all the foreign key constraints and everything set as they shoudl be. Every time someone rates a picture, I just insert a new record into ratings and be done with it. To find the average rating of a picture, I'd just run something like this: SELECT AVG(rating) FROM ratings WHERE pictureID = '5' GROUP by pictureID Having it setup this way lets me run my fancy statistics to. I can easily find who rated a certain picture a 3, and what not. Now I'm thinking if there's a crapload of ratings (which is very possible in what I'm really designing), finding the average will became very expensive and painful. Using a non-normalized version would seem to be more efficient. e.g.: Table picture id | picture | userID | ratingOne | ratingTwo | ratingThree | ratingFour | ratingFive To calculate the average, I'd just have to select a single row. It seems so much more efficient, but so much more uglier. Can someone point me in the right direction of what to do? My initial research shows that I have to "find the right balance", but how do I go about finding that balance? Any articles or additional reading information would be appreciated as well. Thanks.

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  • Sinatra application running on Dreamhost suddenly not working

    - by jbrennan
    My Sinatra application was running fine on Dreamhost until a few days ago (I'm not sure precisely when it went bad). Now when I visit my app I get this error: can't activate rack (~> 1.1, runtime) for ["sinatra-1.1.2"], already activated rack-1.2.1 for [] I have no idea how to fix this. I've tried updating all my gems, then touching the app/tmp/restart.txt file, but still no fix. I hadn't touched any files of my app, nor my Dreamhost account. It just busted on its own (my guess is DH changed something on their server which caused the bust). When I originally deployed my app, I had to go through some hoops to get it working, and I seem to think I was using gems in a custom location, but I can't remember exactly where or how. I don't know my way around Rack/Passenger very well. Here's my config.ru: (mostly grafted from around the web, I don't fully understand it) ENV['RACK_ENV'] = 'development' if ENV['RACK_ENV'].empty? #### Make sure my own gem path is included first ENV['GEM_HOME'] = "#{ENV['HOME']}/.gems" ENV['GEM_PATH'] = "#{ENV['HOME']}/.gems:" require 'rubygems' Gem.clear_paths ## NB! key part require 'sinatra' set :env, :production disable :run require 'MY_APP_NAME.rb' run Sinatra::Application

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  • Updating nullability of columns in SQL 2008

    - by Shaul
    I have a very wide table, containing lots and lots of bit fields. These bit fields were originally set up as nullable. Now we've just made a decision that it doesn't make sense to have them nullable; the value is either Yes or No, default No. In other words, the schema should change from: create table MyTable( ID bigint not null, Name varchar(100) not null, BitField1 bit null, BitField2 bit null, ... BitFieldN bit null ) to create table MyTable( ID bigint not null, Name varchar(100) not null, BitField1 bit not null, BitField2 bit not null, ... BitFieldN bit not null ) alter table MyTable add constraint DF_BitField1 default 0 for BitField1 alter table MyTable add constraint DF_BitField2 default 0 for BitField2 alter table MyTable add constraint DF_BitField3 default 0 for BitField3 So I've just gone in through the SQL Management Studio, updating all these fields to non-nullable, default value 0. And guess what - when I try to update it, SQL Mgmt studio internally recreates the table and then tries to reinsert all the data into the new table... including the null values! Which of course generates an error, because it's explicitly trying to insert a null value into a non-nullable column. Aaargh! Obviously I could run N update statements of the form: update MyTable set BitField1 = 0 where BitField1 is null update MyTable set BitField2 = 0 where BitField2 is null but as I said before, there are n fields out there, and what's more, this change has to propagate out to several identical databases. Very painful to implement manually. Is there any way to make the table modification just ignore the null values and allow the default rule to kick in when you attempt to insert a null value?

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  • Rails named_scope across multiple tables

    - by wakiki
    I'm trying to tidy up my code by using named_scopes in Rails 2.3.x but where I'm struggling with the has_many :through associations. I'm wondering if I'm putting the scopes in the wrong place... Here's some pseudo code below. The problem is that the :accepted named scope is replicated twice... I could of course call :accepted something different but these are the statuses on the table and it seems wrong to call them something different. Can anyone shed light on whether I'm doing the following correctly or not? I know Rails 3 is out but it's still in beta and it's a big project I'm doing so I can't use it in production yet. class Person < ActiveRecord::Base has_many :connections has_many :contacts, :through => :connections named_scope :accepted, :conditions => ["connections.status = ?", Connection::ACCEPTED] # the :accepted named_scope is duplicated named_scope :accepted, :conditions => ["memberships.status = ?", Membership::ACCEPTED] end class Group < ActiveRecord::Base has_many :memberships has_many :members, :through => :memberships end class Connection < ActiveRecord::Base belongs_to :person belongs_to :contact, :class_name => "Person", :foreign_key => "contact_id" end class Membership < ActiveRecord::Base belongs_to :person belongs_to :group end I'm trying to run something like person.contacts.accepted and group.members.accepted which are two different things. Shouldn't the named_scopes be in the Membership and Connection classes? One solution is to just call the two different named scope something different in the Person class or even to create separate associations (ie. has_many :accepted_members and has_many :accepted_contacts) but it seems hackish and in reality I have many more than just accepted (ie. banned members, ignored connections, pending, requested etc etc)

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  • How can I display an ASP.NET MVC html part from one application in another

    - by Frank Sessions
    We have several asp.net MVC apps in the following setup SecurityApp (root application - handles forms auth for SSO and has a profile edit page) Application1 (virtual directory) Application2 (virtual directory) Application3 (virtual directory) so that domain.com points to SecurityApp and domain.com/Application1 etc point to their associated virtual directories. All of our Single Sign On (SSO) is working properly using forms authentication. Based on the users permissions when logging in a menu that lists their available applications and a logout link will be generated and saved in the cache - this menu displays fine whenever the user is in the SecurityApp (editing their profile) but we cannot figure out how to get the Applications in the virtual directories to display the same application menu. We have tried: 1) Using JSONP to do an request that will return the html for the menu. The ajax call returns the HTML with the html; however, because User.IsAuthenticated is false the menu comes back empty. 2) We created a user control and include it along with the dll's for the SecurityApp project and this works; however, we dont want to have to include all the dlls for the SecurityApp project in every application that we create (along with all the app settings in the web.config) We would like this to be as simple as possible to implement so that anyone creating a new app can add the menu to their application in as few steps as possible... Any ideas? To Clarify - we are using ASP.NET MVC 1.0 since these apps are in production and we do not have the okay to go to ASP.NET MVC 2.0 (unfortunately)

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  • Child sProc cannot reference a Local temp table created in parent sProc

    - by John Galt
    On our production SQL2000 instance, we have a database with hundreds of stored procedures, many of which use a technique of creating a #TEMP table "early" on in the code and then various inner stored procedures get EXECUTEd by this parent sProc. In SQL2000, the inner or "child" sProc have no problem INSERTing into #TEMP or SELECTing data from #TEMP. In short, I assume they can all refer to this #TEMP because they use the same connection. In testing with SQL2008, I find 2 manifestations of different behavior. First, at design time, the new "intellisense" feature is complaining in Management Studio EDIT of the child sProc that #TEMP is an "invalid object name". But worse is that at execution time, the invoked parent sProc fails inside the nested child sProc. Someone suggested that the solution is to change to ##TEMP which is apparently a global temporary table which can be referenced from different connections. That seems too drastic a proposal both from the amount of work to chase down all the problem spots as well as possible/probable nasty effects when these sProcs are invoked from web applications (i.e. multiuser issues). Is this indeed a change in behavior in SQL2005 or SQL2008 regarding #TEMP (local temp tables)? We skipped 2005 but I'd like to learn more precisely why this is occuring before I go off and try to hack out the needed fixes. Thanks.

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  • ColdFusion blank page in IE7 on refresh?

    - by richardtallent
    I'm new to ColdFusion, have a very basic problem that's really slowing me down. I'm making edits in a text editor and refreshing the page in web browsers for testing. Standard web dev stuff, no browser-sniffing, redirection, or other weirdness, and no proxies involved. When I refresh the page in Chrome or Firefox, everything works fine, but when I refresh in IE7, I get a blank page. View Source shows me: <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=Content-Type content="text/html; charset=utf-8"></HEAD> <BODY></BODY></HTML> That's it. While I am rendering to the transitional DTD, the real head contains a title, etc. My development server is CF 9, production is 8. This problem has been happening in both. Seems it may only be happening on pages that are the the result of a POST action. I've never experienced this in ASP.NET (my usual development environment) using the same browsers.

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  • Finding usage of jQuery UI in a big ugly codebase

    - by Daniel Magliola
    I've recently inherited the maintenance of a big, ugly codebase for a production website. Poke your eyes out ugly. And though it's big, it's mostly PHP code, it doesn't have much JS, besides a few "ajaxy" things in the UI. Our main current problem is that the site is just too heavy. Homepage weighs in at 1.6 Mb currently, so I'm trying to clean some stuff out. One of the main wasters is that every single page includes the jQuery UI library, but I don't think it's used at all. It's definitely not being used in the homepage and in most pages, so I want to only include the where necessary. I'm not really experienced with jQuery, i'm more of a Prototype guy, so I'm wondering. Is there anything I could search for that'd let me know where jQuery UI is being used? What i'm looking for is "common strings", component names, etc For example, if this was scriptaculous, i'd look for things like "Draggable", "Effect", etc. Any suggestions for jQuery UI? (Of course, if you can think of a more robust way of removing the tag from pages that don't use it without breaking everything, I'd love to hear about it) Thanks!! Daniel

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  • Can Haskell's Parsec library be used to implement a recursive descent parser with backup?

    - by Thor Thurn
    I've been considering using Haskell's Parsec parsing library to parse a subset of Java as a recursive descent parser as an alternative to more traditional parser-generator solutions like Happy. Parsec seems very easy to use, and parse speed is definitely not a factor for me. I'm wondering, though, if it's possible to implement "backup" with Parsec, a technique which finds the correct production to use by trying each one in turn. For a simple example, consider the very start of the JLS Java grammar: Literal: IntegerLiteral FloatingPointLiteral I'd like a way to not have to figure out how I should order these two rules to get the parse to succeed. As it stands, a naive implementation like this: literal = do { x <- try (do { v <- integer; return (IntLiteral v)}) <|> (do { v <- float; return (FPLiteral v)}); return(Literal x) } Will not work... inputs like "15.2" will cause the integer parser to succeed first, and then the whole thing will choke on the "." symbol. In this case, of course, it's obvious that you can solve the problem by re-ordering the two productions. In the general case, though, finding things like this is going to be a nightmare, and it's very likely that I'll miss some cases. Ideally, I'd like a way to have Parsec figure out stuff like this for me. Is this possible, or am I simply trying to do too much with the library? The Parsec documentation claims that it can "parse context-sensitive, infinite look-ahead grammars", so it seems like something like I should be able to do something here.

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  • Minimum privileges to read SQL Jobs using SQL SMO

    - by Gustavo Cavalcanti
    I wrote an application to use SQL SMO to find all SQL Servers, databases, jobs and job outcomes. This application is executed through a scheduled task using a local service account. This service account is local to the application server only and is not present in any SQL Server to be inspected. I am having problems getting information on job and job outcomes when connecting to the servers using a user with dbReader rights on system tables. If we set the user to be sysadmin on the server it all works fine. My question to you is: What are the minimum privileges a local SQL Server user needs to have in order to connect to the server and inspect jobs/job outcomes using the SQL SMO API? I connect to each SQL Server by doing the following: var conn = new ServerConnection { LoginSecure = false, ApplicationName = "SQL Inspector", ServerInstance = serverInstanceName, ConnectAsUser = false, Login = user, Password = password }; var smoServer = new Server (conn); I read the jobs by reading smoServer.JobServer.Jobs and read the JobSteps property on each of these jobs. The variable server is of type Microsoft.SqlServer.Management.Smo.Server. user/password are of the user found in each SQL Server to be inspected. If "user" is SysAdmin on the SQL Server to be inspected all works ok, as well as if we set ConnectAsUser to true and execute the scheduled task using my own credentials, which grants me SysAdmin privileges on SQL Server per my Active Directory membership. Thanks!

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  • Sql Serve - Cascade delete has multiple paths

    - by Anders Juul
    Hi all, I have two tables, Results and ComparedResults. ComparedResults has two columns which reference the primary key of the Results table. My problem is that if a record in Results is deleted, I wish to delete all records in ComparedResults which reference the deleted record, regardless of whether it's one column or the other (and the columns may reference the same Results row). A row in Results may deleted directly or through cascade delete caused by deleting in a third table. Googling this could indicate that I need to disable cascade delete and rewrite all cascade deletes to use triggers instead. Is that REALLY nessesary? I'd be prepared to do much restructuring of the database to avoid this, as my main area is OO programming, and databases should 'just work'. It is hard to see, however, how a restructuring could help as I would just move the problem around... Or am I missing something? I am also a bit at a loss as to why my initial construct should even be a problem for the Sql Server?! Any comments welcome and much appreciated! Anders, Denmark

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  • Is their a definitive list for the differences between the current version of SQL Azure and SQL Serv

    - by Aim Kai
    I am a relative newbie when it comes to SQL Azure!! I was wondering if there was a definitive list somewhere regarding what is and is not supported by SQL Azure in regards to SQL Server 2008? I have had a look through google but I've noticed some of the blog posts are missing things which I have found through my own testing: For example, quite a lot is summarised in this blog entry http://www.keepitsimpleandfast.com/2009/12/main-differences-between-sql-azure-and.html Common Language Runtime (CLR) Database file placement Database mirroring Distributed queries Distributed transactions Filegroup management Global temporary tables Spatial data and indexes SQL Server configuration options SQL Server Service Broker System tables Trace Flags which is a repeat of the MSDN page http://msdn.microsoft.com/en-us/library/ff394115.aspx I've noticed from my own testing that the following seem to have issues when migrating from SQL Server 2008 to the Azure: XML Types (the msdn does mention large custom types - I guess it may include this?? even if the data schema is really small?) Multi-part views I've been using SQL Azure Migration Wizard v3.1.8 to migrate local databases into the cloud. I was wondering if anyone could point to a list or give me any information till when these features are likely to be included in SQL Azure.

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  • How should a one-man development shop document their code?

    - by CKoenig
    Hi, please let me first describe my situation. I work in an IT department for a small-to-medium sized industrial-company and basically I'm the only real developer (sometimes a second guy joins in for his own projects). I programm mostly in C#/.net. Of course I only programm for internal need (Intranet, reporting, data-driven apps, some mobile apps, ...). My question is how should I document my work? It's a highly dynamic environment (the features and bug fixes I implement are tested by me during production, and go live, often within a day. If I technical documentation like MSDN or even overview diagramms those would take me more time to sync than the whole programming process. Also I feel it's a waste of time because I would be the only one who ever read it. I do understand that if I get sick, leave, or forget this documentation would be valuable. PS:well of course you are right - the quesion is how much and how/where. I try using the XML-docu comments for the public exposed parts but as I'm a believer in self-documenting code the comments mostly restates in plain text what you can read from the method-head itself :(Maybe using the remarks section is the key but if you have 30 lines of code with a 15 line xml-comment in front it just looks dirty (sorry for posting it here but our firewall rejects JSON :( )

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  • protecting grails melody with grails filter

    - by batmannavneet
    I have an application where I am using spring security along with grails melody. I am planning to run grails melody in production environment, but don't want visitors to have access to it. How should I achieve that ? I tried creating a filter in grails (just showing the sample of what I am trying, not the actual code)- def filters = { allURIs(uri:'/**') { before = { //... if(request.forwardURI.indexOf("admin") != -1 || request.forwardURI.indexOf("monitoring") != -1) { response.sendError 404 return false } } } } But this doesnt work as the request for "monitoring" doesnt hit this filter. I dont even want the user to know that such a URL exists, so I want to check in the filter that if "monitoring" is the URL, I show the 404 error page. Thats also the reason why I dont want to protect this URL with spring security as it will show "access denied" page. Basically I want the URL to exist but they should be invisible to users. I want the access to be open to only certain IP addresses for these special URLs. On another note, Is it possible to write a grails filter that "acts" before the spring security filter is hit ? I want to be able to do some filtering before I forward requests to spring security. Writing a grails filter like above doesnt help. Spring security filter gets hit first if I access a protected resource and this filter doesn't get called. Thanks

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  • Why put a DAO layer over a persistence layer (like JDO or Hibernate)

    - by Todd Owen
    Data Access Objects (DAOs) are a common design pattern, and recommended by Sun. But the earliest examples of Java DAOs interacted directly with relational databases -- they were, in essence, doing object-relational mapping (ORM). Nowadays, I see DAOs on top of mature ORM frameworks like JDO and Hibernate, and I wonder if that is really a good idea. I am developing a web service using JDO as the persistence layer, and am considering whether or not to introduce DAOs. I foresee a problem when dealing with a particular class which contains a map of other objects: public class Book { // Book description in various languages, indexed by ISO language codes private Map<String,BookDescription> descriptions; } JDO is clever enough to map this to a foreign key constraint between the "BOOKS" and "BOOKDESCRIPTIONS" tables. It transparently loads the BookDescription objects (using lazy loading, I believe), and persists them when the Book object is persisted. If I was to introduce a "data access layer" and write a class like BookDao, and encapsulate all the JDO code within this, then wouldn't this JDO's transparent loading of the child objects be circumventing the data access layer? For consistency, shouldn't all the BookDescription objects be loaded and persisted via some BookDescriptionDao object (or BookDao.loadDescription method)? Yet refactoring in that way would make manipulating the model needlessly complicated. So my question is, what's wrong with calling JDO (or Hibernate, or whatever ORM you fancy) directly in the business layer? Its syntax is already quite concise, and it is datastore-agnostic. What is the advantage, if any, of encapsulating it in Data Access Objects?

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  • Reasons for & against a Database

    - by dbemerlin
    Hi, i had a discussion with a coworker about the architecture of a program i'm writing and i'd like some more opinions. The Situation: The Program should update at near-realtime (+/- 1 Minute). It involves the movement of objects on a coordinate system. There are some events that occur at regular intervals (i.e. creation of the objects). Movements can change at any time through user input. My solution was: Build a server that runs continously and stores the data internally. The server dumps a state-of-the-program at regular intervals to protect against powerfailures and/or crashes. He argued that the program requires a Database and i should use cronjobs to update the data. I can store movement information by storing startpoint, endpoint and speed and update the position in the cronjob (and calculate collisions with other objects there) by calculating direction and speed. His reasons: Requires more CPU & Memory because it runs constantly. Powerfailures/Crashes might destroy data. Databases are faster. My reasons against this are mostly: Not very precise as events can only occur at full minutes (wouldn't be that bad though). Requires (possibly costly) transformation of data on every run from relational data to objects. RDBMS are a general solution for a specialized problem so a specialized solution should be more efficient. Powerfailures (or other crashes) can leave the Data in an undefined state with only partially updated data unless (possibly costly) precautions (like transactions) are taken. What are your opinions about that? Which arguments can you add for any side?

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  • MySQL GIS and Spatial Extensions - how to map regions and query against them

    - by chibineku
    I am trying to make a smartphone app which will return a list of users within a certain proximity, say 100m. It's easy to get the coordinates of my BlackBerry and write them to a database, but in order to return a list of other users within 100m, I need to pull every other record from the database and compare the distance between the two points, checking to see if it's within range, before outputting that user's information. This is going to be time consuming if there are many users involved. So I would like to map areas (countries, cities, I'm not yet sure of the resolution I'll need) so that I can first target a smaller subset of all users. This will save on processing time. I have read the basics of GIS and spatial querying on the mysql website but to be honest the query is over my head and I hate copying and pasting code without understanding it. Plus it only checks for proximity - I want to first check if a coordinate falls within a certain area. Does anyone have any experience of such matters and feel like giving me some pointers? Resources such as any preexisting databases of points describing countries as polygons would be really helpful too. Many thanks to anyone who takes the time :)

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  • How to organize integrity tests and code unit tests?

    - by karlthorwald
    I have several files with code testing code (which uses a "unittest" class). Later I found it would be nice to test database integrity also. I put this into a separate directory tree. (Things like the keys have correct format, parent and child nodes are pointing correctly and such.) I use the same unittest class for the integrity tests. Now I wonder if it makes really sense to keep this separate. To test the integrity of data I often duplicate parts of code that I use to test the code that handles the data. But it is not the same. The code tests use test databases (that get deleted after each test) and the integrity tests connect to the live data and analyze it. The integrity tests I want to call from cron and send an alarm if something happens in the live database. How would you handle that? Are there standards for such a setup? What is your experience? My tendency is to put everything in the same file, which would result in the code tests also being executed by the cron on the production environment.

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  • Merging datasets with 2 different time variables in SAS

    - by John
    Hye Guys, for those regularly browsing this site sorry for already another question (however I did solve my last question myself!) I have another problem with merging datasets, it seems that accounting for time in datasets is a real pain in the ass. I succesfully managed to merge on months in my previous datasets, however it seems I have a final dataset which only has quarter as a time count variable. So where all my normal databases have month 1- xxx as an indicator of time, this database had quarter as an indicator of time. I still want to add the variables of this last database, let's call it TVOL, into my WORK database. Quick summary QUARTER: Quarter 0 = JAN1996-MAR1996 Month: Month 0 = JAN1996 Example: TVOL TVOL _ Ticker ____ Quarter 1500 _ AA ________ -1 52546 _ BB ________ 15 Example: WORK BETA _ Ticker ____ Month 1.52 _ AA ________ 2 1.54__ BB _______ 3 Example: Merged: BETA ______ TVOL __ Ticker ____ Month 1.52 _______ 500 ___ AA _______ 2 I now want to merge this 2 tables using following relationship if the month is in quarter 1, the data of quarter 0 has to be used, so if i have an observation i nWORK with date 2FEB1996 the TVOL of quarter -1 has to be put behind this observation. Something like IF month = quarter i use data quarter i-1. Also, as TVOL is measured quarterly and I have to put in monthly I have to take the average, so (TVOL/3) should be added as a variable. Thanks!

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  • How to use HSQLDB in Oracle query syntax mode?

    - by Jan Algermissen
    I am trying to use HSQLDB as an embedded database in a spring application (for testing). As the target production database is Oracle, I would like to use HSQLDBs Oracle syntax mode feature. In the Spring config I use <jdbc:embedded-database type="HSQL" id="dataSource"> </jdbc:embedded-database> <jdbc:initialize-database data-source="dataSource" enabled="true"> <jdbc:script location="classpath:schema.sql"/> </jdbc:initialize-database> And in schema.sql at the top I wrote: SET DATABASE SQL SYNTAX ORA TRUE; However, when running my test, I get the following error: java.sql.SQLException: Unexpected token: DATABASE in statement [SET DATABASE SQL SYNTAX ORA TRUE] Is this a syntax error or a permissions error or something entirely different? Thanks - also for any pointers that might lead to the answer. Given that HSQL is the Spring default for jdbc:embedded-database and given the target is Oracle, this scenario should actually be very common. However, I found nothing on the Web even touching the issue.

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  • Ruby and duck typing: design by contract impossible?

    - by davetron5000
    Method signature in Java: public List<String> getFilesIn(List<File> directories) similar one in ruby def get_files_in(directories) In the case of Java, the type system gives me information about what the method expects and delivers. In Ruby's case, I have no clue what I'm supposed to pass in, or what I'll expect to receive. In Java, the object must formally implement the interface. In Ruby, the object being passed in must respond to whatever methods are called in the method defined here. This seems highly problematic: Even with 100% accurate, up-to-date documentation, the Ruby code has to essentially expose its implementation, breaking encapsulation. "OO purity" aside, this would seem to be a maintenance nightmare. The Ruby code gives me no clue what's being returned; I would have to essentially experiment, or read the code to find out what methods the returned object would respond to. Not looking to debate static typing vs duck typing, but looking to understand how you maintain a production system where you have almost no ability to design by contract. Update No one has really addressed the exposure of a method's internal implementation via documentation that this approach requires. Since there are no interfaces, if I'm not expecting a particular type, don't I have to itemize every method I might call so that the caller knows what can be passed in? Or is this just an edge case that doesn't really come up?

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