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  • One-to-one Mapping issue with NHibernate/Fluent: Foreign Key not updateing

    - by Trevor
    Summary: Parent and Child class. One to one relationship between the Parent and Child. Parent has a FK property which references the primary key of the Child. Code as follows: public class NHTestParent { public virtual Guid NHTestParentId { get; set; } public virtual Guid ChildId { get { return ChildRef.NHTestChildId; } set { } } public virtual string ParentName { get; set; } protected NHTestChild _childRef; public virtual NHTestChild ChildRef { get { if (_childRef == null) _childRef = new NHTestChild(); return _childRef; } set { _childRef = value; } } } public class NHTestChild { public virtual Guid NHTestChildId { get; set; } public virtual string ChildName { get; set; } } With the following Fluent mappings: Parent Mapping Id(x => x.NHTestParentId); Map(x => x.ParentName); Map(x => x.ChildId); References(x => x.ChildRef, "ChildId").Cascade.All(); Child Mapping: Id(x => x.NHTestChildId); Map(x => x.ChildName); If I do something like (pseudo code) ... HTestParent parent = new NHTestParent(); parent.ParentName = "Parent 1"; parent.ChildRef.ChildName = "Child 1"; nhibernateSession.SaveOrUpdate(aParent); Commit; ... I get an error: "Invalid index 3 for this SqlParameterCollection with Count=3" If I change the parent 'References' line as follows (i.e. provide the name of the child property I'm pointing at): References(x => x.ChildRef, "ChildId").PropertyRef("NHTestChildId").Cascade.All(); I get the error: "Unable to resolve property: NHTestChildId" So, I tried the 'HasOne()' reference setting, as follows: HasOne<NHTestChild>(x => x.ChildRef).ForeignKey("ChildId").Cascade.All().Fetch.Join(); This results in the save working, but the load fails to find the child. If I inspect the SQL Nhibernate produces I can see that NHibernate is assuming the Primary key of the parent is the link to the child (i.e. load join condition is "parent.NHTestParentId = child.NHTestChildId). The 'ForeignKey' specified appears to be ignored. I can set any value and no error occurs - the join just always fails and no child is returned. I've tried a number of slight variations on the above. It seems like it should be a simple thing to achieve. Any ideas?

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  • Storing Preferences/One-to-One Relationships in Database

    - by LnDCobra
    What is the best way to store settings for certain objects in my database? Method one: Using a single table Table: Company {CompanyID, CompanyName, AutoEmail, AutoEmailAddress, AutoPrint, AutoPrintPrinter} Method two: Using two tables Table Company {CompanyID, COmpanyName} Table2 CompanySettings{CompanyID, utoEmail, AutoEmailAddress, AutoPrint, AutoPrintPrinter}

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  • Ruby on Rails: create records for multiple models with one form and one submit

    - by notblakeshelton
    I have a 3 models: quote, customer, and item. Each quote has one customer and one item. I would like to create a new quote, a new customer, and a new item in their respective tables when I press the submit button. I have looked at other questions and railscasts and either they don't work for my situation or I don't know how to implement them. I also want my index page to be the page where I can create everything. quote.rb class Quote < ActiveRecord::Base attr_accessible :quote_number has_one :customer has_one :item end customer.rb class Customer < ActiveRecord::Base #unsure of what to put here #a customer can have multiple quotes, so would i use: has_many :quotes #<----? end item.rb class Item < ActiveRecord::Base #also unsure about this #each item can also be in multiple quotes quotes_controller.rb class QuotesController < ApplicationController def index @quote = Quote.new @customer = Customer.new @item = item.new end def create @quote = Quote.new(params[:quote]) @quote.save @customer = Customer.new(params[:customer]) @customer.save @item = Item.new(params[:item]) @item.save end end items_controller.rb class ItemsController < ApplicationController def index end def new @item = Item.new end def create @item = Item.new(params[:item]) @item.save end end customers_controller.rb class CustomersController < ApplicationController def index end def new @customer = Customer.new end def create @customer = Customer.new(params[:customer]) @customer.save end end quotes/index.html.erb <%= form_for @quote do |f| %> <%= f.fields_for @customer do |builder| %> <%= label_tag :firstname %> <%= builder.text_field :firstname %> <%= label_tag :lastname %> <%= builder.text_field :lastname %> <% end %> <%= f.fields_for @item do |builder| %> <%= label_tag :name %> <%= builder.text_field :name %> <%= label_tag :description %> <%= builder.text_field :description %> <% end %> <%= label_tag :quote_number %> <%= f.text_field :quote_number %> <%= f.submit %> <% end %> When I try submitting that I get an error: Can't mass-assign protected attributes: item, customer So to try and fix it I updated the attr_accessible in quote.rb to include :item, :customer but then I get this error: Item(#) expected, got ActiveSupport::HashWithIndifferentAccess(#) Any help would be greatly appreciated.

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  • ROOT_MISMATCH error after following FAQ directions

    - by Adko
    While using Ubuntu One in 11.04 I am unable to change my account info. When I made the switch to 11.04 I forgot that I already had an Ubuntu One account so, I made a new one. However, upon going through one of my email accounts I found my old Ubuntu One login information. I then attempted to switch the account associated with my desktop to my first email. Now, despite following the directions found at https://wiki.ubuntu.com/UbuntuOne/FAQ/WhatToDoWhenSyncdaemonSaysRootMismatch I continue to get the error "File sync error. (local and server roots are different (ROOT_MISMATCH))". Any help would be appreciated.

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  • Does a mini PCIe SSD fit into a Acer Aspire One?

    - by Narcolapser
    Question: What, if any, mini PCIe SSDs fit into the mini PCIe slot of the Acer Aspire one AOD250? Info: I have an Aspire One and I've been considering loading it with an SSD. The mini PCIe drives fascinate me and so I want to try that approach. Also they tend to be cheaper and not much slower. (at least not on Read time which matters more for a netbook) But I've heard that some times computers don't support certain mini PCIe cards. And I was wondering if anyone knew about the Aspire One? I tried asking Acer tech support, but they didn't know jack and spent the whole time informing that I would have to support my Ubuntu install on my own, which I was. Anyway. Rant Aside, I'm looking at this drive: http://www.newegg.com/Product/Product.aspx?Item=N82E16820183252 It states it is exclusively for the Eee PC. now does that mean It was designed for the Eee PC but will work in my netbook. or is something going to go wrong? (like right now my concern is it physically not fitting.) Any information would be appreciated. o7

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  • Two UIViews, one UIViewController (in one UINavigationController)

    - by jdandrea
    Given an iPhone app with a UITableViewController pushed onto a UINavigationController, I would like to add a right bar button item to toggle between the table view and an "alternate" view of the same data. Let's also say that this other view uses the same data but is not a UITableView. Now, I know variations on this question already exist on Stack Overflow. However, in this case, that alternate view would not be pushed onto the UINavigationController. It would be visually akin to flipping the current UIViewController's table view over and revealing the other view, then being able to flip back. In other words, it's intended to take up a single spot in the UINavigationController hierarchy. Moreover, whatever selection you ultimately make from within either view will push a common UIViewController onto the UINavigationController stack. Still more info: We don't want to use a separate UINavigationController just to handle this pair of views, and we don't want to split these apart via a UITabBarController either. Visually and contextually, the UX is meant to show two sides of the same coin. It's just that those two sides happen to involve their own View Controllers in normal practice. Now … it turns out I have already gone and quickly set this up to see how it might work! However, upon stepping back to examine it, I get the distinct impression that I went about it in a rather non-MVC way, which of course concerns me a bit. Here's what I did at a high level. Right now, I have a UIViewController (not a UITableViewController) that handles all commonalities between the two views, such as fetching the raw data. I also have two NIBs, one for each view, and two UIView objects to go along with them. (One of them is a UITableView, which is a kind of UIView.) I switch between the views using animation (easy enough). Also, in an effort to keep things encapsulated, the now-split-apart UITableView (not the UIViewController!) acts as its own delegate and data source, fetching data from the VC. The VC is set up as a weak, non-retained object in the table view. In parallel, the alternate view gets at the raw data from the VC in the exact same way. So, there are a few things that smell funny here. The weak linking from child to parent, while polite, seems like it might be wrong. Making a UITableView the table's data source and delegate also seems odd to me, thinking that a view controller is where you want to put that per Apple's MVC diagrams. As it stands now, it would appear as if the view knows about the model, which isn't good. Loading up both views in advance also seems odd, because lazy loading is no longer in effect. Losing the benefits of a UITableViewController (like auto-scrolling to cells with text fields) is also a bit frustrating, and I'd rather not reinvent the wheel to work around that as well. Given all of the above, and given we want that "flip effect" in the context of a single spot on a single UINavigationController, and given that both views are two sides of the same coin, is there a better, more obvious way to design this that I'm just happening to miss completely? Clues appreciated!

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  • how to get the result query one by one in jsp and mysql

    - by user261002
    I am trying to implement as Online Mock exam in JSP, but I have a problem to get the questions one by one, it get connceted for the first time, and show me the first question and answers, but when I click on "next" again, it still show me the first question, I think by clicking on "next" it start querying again. please help me. this is my bean : database.SQLSelectStatement sqlselect; database.SQLSelectStatement sqlselect2; static ResultSet questions; static ResultSetMetaData rsm; static ResultSet answers; public void setConnection() throws SQLException { if (database.DatabaseManager.getInstance().connectionOK()) { sqlselect = new database.SQLSelectStatement("question", "question", "0"); sqlselect2 = new database.SQLSelectStatement("answers", "question_id", "0"); questions = sqlselect.executeWithNoCondition(); } } public int i=0; public String getQuestions() throws SQLException { String result = ""; rsm = questions.getMetaData(); for (int i = 0; i < rsm.getColumnCount(); i++) { result += "<th>" + rsm.getColumnName(i + 1) + "</th>"; } if (!questions.isLast()) { questions.next(); System.out.println(i+1); result += "<tr>"; result += "<td>" + questions.getInt(1) + "</td>"; result += "<td>" + questions.getString(2) + "</td>"; result += "</tr>"; result += "<tr>"; sqlselect2.setValue(String.valueOf(questions.getInt(1))); answers = sqlselect2.Execute(); while (answers.next()) { result += "<tr> <td colspan='2'><input type='radio' name='answer' value='" + answers.getString(2) + "'> " + answers.getString(2) + "</td></tr>"; } result += "</tr>"; answers.close(); } return result; } this is the HTML: <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>JSP Page</title> </head> <body> <h1>JSP Page</h1> <jsp:useBean id="exam" class="exam.ExamQuestions"></jsp:useBean> <% exam.setConnection(); %> <form method="post"> <table > <%=exam.getQuestions()%> </table> <input type="submit" name="action" value="next"/> </form> <% String action = request.getParameter("action"); if ("next".equals(action)) { out.println(request.getParameter("answer")); } %> </body> </html>

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  • Does HashMap provide a one to one correspondence?

    - by Roman
    I found the following statement: Map is an object that stores key/volume pairs. Given a key, you can find its value. Keys must be unique, but values may be duplicated. For example I have just one key/value pair (3,4). And now I put a new pair (3,5). It will remove the old pair. Right? But if I put (2,4) instead of (3,4) I will add a new pair of key/value to the HashMap. Right?

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  • C++: Most common way to talk to one application from the other one

    - by MInner
    In bare outlines, I've got an application which looks through the directories at startup and creates special files' index - after that it works like daemon. The other application creates such 'special' files and places them in some directory. What way of informing the first application about a new file (to index it) is the most common, simple (the first one is run-time, so it shouldn't slow it too much), and cross-platform if it is possible? I've looked through RPC and IPC but they are too heavy (also non-cross-platform and slow (need a lot of features to work - I need a simple light well-working way), probably).

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  • Selecting one object from a one-to-many relationship in Hibernate

    - by Nick Thomson
    I have two tables: Job job_id, <other data> Job_Link job_link_id, job_id, start_timestamp, end_timestamp, <other data> There may be multiple records in Job_Link specifying the same job_id with the start_timestamp and end_timestamps to indicate when those records are considered "current", it is guaranteed that start_timestamp and end_timestamp will not overlap. We have entities for both the Job and Job_Link tables and defining a one-to-many relationship to load all the job_links wouldn't be a problem. However we'd like to avoid that and have a single job_link item in the Job entity that will contain only the "current" Job_Link object. Is there any way to achive that?

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  • Are Motherboards for the Acer Aspire One AOA150 Netbook Compatible with the AOA110?

    - by Mindstormscreator
    I have an Acer Aspire One ZG5 AOA110-1588 netbook, and the motherboard doesn't have a port for a SATA 2.5 inch hard drive; it only supports this slow 8GB SSD type drive. Through research I've discovered that the AOA150 motherboards do have a SATA slot, and the bottom plate of these laptops have an appropriate protrusion for the drive to fit in (for example, compare this to this). The AOA110 and AOA150 models are very similar in appearance and specs. I've even seen tutorials that involve soldering a SATA connector onto the AOA110's motherboard, essentially creating an AOA150 motherboard (right?) So, could I just swap out the motherboard in my netbook with the MBS0506001? (I'd post another link to the actual board but can't because of the spam prevention...) I assume I would also need to purchase and replace the bottom cover with a larger one and possibly get a hard drive caddy as well...? Thanks!

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  • How to connect to a PEAP GTC wifi network with Android 2.2 on a nexus one?

    - by Glen
    Hi, I recently updated my nexus one to 2.2. Now I can't connect to my uni's wifi. They use PEAP with GTC. I had it working fine on 2.1. Also it works fine on my Ubuntu laptop. I have entered my uni number (user name) in the identity box. I have entered my password in the password box. I have emailed the certificated that works on Ubuntu to my self and installed it on the nexus one. I have enabled secure credentials. What am I doing wrong? Thanks, Glen.

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  • Cloud storage services offering one-time download links? [closed]

    - by TARehman
    Is anyone aware of consumer-targeted cloud storage services that allow users to generate a one-time download link for hosted files? Case in point: I have an encrypted container with some documents I need to send to a vendor. I would prefer to give them a one-time download link, so that I know when they have accessed the file, and then inform them of the passphrase by phone. I have heard that MediaFire offers 1-time links, but that they are buried in tons of advertising. At the moment, I'm not sure that I consider MediaFire fully legitimate; I'm more interested in solutions with Google Drive, Box.net, DropBox, etc.

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  • Entity Framework: insert with one-to-one reference

    - by bomortensen
    Hi 'overflow! I'm having a bit trouble inserting into a mssql database using Entity Framework. There's two tables that I want to insert into, where one of table 1s fields is a foreign key in table2. This is the code I have so far: Media media = null; foreach(POI p in poiList) { media = new Media() { Path = p.ImagePath, Title = p.Title }; if (media != null && !context.Media.Any(me => me.Title == p.ImageTitle)) { context.AddToMedia(media); context.SaveChanges(); } PointOfInterest poi = new PointOfInterest() { Altitude = 2000.0, ID = p.ID, Latitude = p.Latitude, Longitude = p.Longitude, LatitudeRoute = p.LatitudeRoute, LongitudeRoute = p.LongitudeRoute, Description = p.Description, Title = p.Title, DefaultImageID = media.ID, }; context.AddToPointOfInterest(poi); } context.SaveChanges(); The following gives me this error: An object with the same key already exists in the ObjectStateManagerAn object with the same key already exists in the ObjectStateManager I'm still learning how to use the entity framework, so I don't even know if this would be the right approach to insert into two referenced tables. Can anyone enlighten me on this? :) Any help would be greatly appreciated! Thanks!

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  • PHP/MySQL - Working with two databases, one shared and one local to an instance of application

    - by Extrakun
    The situation: Using a off-the-shelf PHP application, I have to add in a new module for extra functionality. Today, it is made known that eventually four different instances of the application are to be deployed, but the data from the new functionality is to be shared among those 4 instances. Each instance should still have their own database for users, content and etc. So the data for the new functionality goes into a 'shared' database. The data for the application (user login, content, uploads) go into a 'local' database To make things more complex, the new module I am writing will fetch data from the local DB and the shared DB at the same time. A re-write of the base application will take too long. I only have control over the new module which I am writing. The ideal solution: Is there a way to encapsulate 2 databases into one name using MySQL? I do not wish to switch DB connections or specifically name the DB to query from inside my SQL statements. The application uses a DB wrapper, so I am able to change it somehow so I can invisibly attempt to read/write to two different DB. What is the best way to handle this problem?

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  • Entity Framework one-to-one relationship mapping flattened in code

    - by Josh Close
    I have a table structure like so. Address: AddressId int not null primary key identity ...more columns AddressContinental: AddressId int not null primary key identity foreign key to pk of Address County State AddressInternational: AddressId int not null primary key identity foreign key to pk of Address ProvinceRegion I don't have control over schema, this is just the way it is. Now, what I want to do is have a single Address object. public class Address { public int AddressId { get; set; } public County County { get; set; } public State State { get; set } public ProvinceRegion { get; set; } } I want to have EF pull it out of the database as a single entity. When saving, I want to save the single entity and have EF know to split it into the three tables. How would I map this in EF 4.1 Code First? I've been searching around and haven't found anything that meets my case yet. UPDATE An address record will have a record in Address and one in either AddressContinental or AddressInternational, but not both.

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  • When destroying one record, another one gets destroyed

    - by normalocity
    Products (like an iPod Classic) :has_many = :listings, :dependent = :destroy Listings (like "My name is Joe, and I have an iPod for sale) :belongs_to = :product So, if I delete a given Product, all the listings that point to it get deleted. That makes sense, and is by design. However, I am writing a "merge" function, where you merge two Products into one, and combine their Listings. So, let's say my two products are "iPod Color" and "iPod Classic", and I want to merge the two. What I want to do is say, "iPod Color, merge into iPod Classic", and result should be that: All the iPod Color Listings are re-pointed to the iPod Classic product After the product_id change, the Listing(s) are saved I then delete the "iPod Color" product Well, that should all work fine, without deleting any Listings. However, I've got this controller, and for whatever reason when I destroy the "iPod Color" Product, even after confirming that the Listings have been moved to "iPod Classic" and saved to the database, the Listings that were previously pointed to "iPod Color" get destroyed as well, and I can't figure out why. It's as if they are retaining some kind of link to the destroyed product, and therefore begin destroyed themselves. What painfully obvious thing am I missing? def merge merging_from = Product.find(params[:id]) merging_to = Product.find_by_model(params[:merging_to]) unless merging_to.nil? unless merging_from.nil? unless merging_from == merging_to # you don't want to merge something with itself merging_from.listings.each do |l| l.product = merging_to l.save end # through some debugging, I've confirmed that my missing Listings are disappearing as a result of the following destroy call merging_from.destroy end end end

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  • XSLT, process elements one by one

    - by qui
    Hi I am quite weak at XSLT so this might seem obvious. Here is some sample XML <term> <name>cholecystocolonic fistula</name> <definition>blah blah</definition> <reference>cholecystocolostomy</reference> </term> And here is the XSLT I wrote a while ago to process it <xsl:template name="term"> { "dictitle": "<xsl:value-of select="name" disable-output-escaping="yes" />", "html": "<xsl:value-of select="definition" disable-output-escaping="yes"/>", "referece": "<xsl:value-of select="reference" disable-output-escaping="yes"/> } </xsl:template> Basically I am creating JSON from the XML. The requirements have now changed so that now the XML can have more than one definition tag and reference tag. They can appear in any order, i.e definition, reference, reference, definition, reference. How can I update the XSLT to accommodate this? Probably worth mentioning that because my XSLT processor is using .NET I can only use XSLT 1.0 commands. Many thanks!

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  • how to pass one variable value frm one class to the oder

    - by Arunabha
    i hav two packages one is com.firstBooks.series.db.parser which hav a java file XMLParser.java,i hav another package com.firstBooks.series79 which hav a class called AppMain.NW i want to send the value of a variable called _xmlFileName frm AppMain class to the xmlFile variable in XMLParser class,i am posting the codes for both the class,kindly help me. package com.firstBooks.series.db.parser; import java.io.IOException; import java.io.InputStream; import java.util.Vector; import net.rim.device.api.xml.parsers.DocumentBuilder; import net.rim.device.api.xml.parsers.DocumentBuilderFactory; import net.rim.device.api.xml.parsers.ParserConfigurationException; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.NodeList; import org.xml.sax.SAXException; import com.firstBooks.series.db.Question; public class XMLParser { private Document document; public static Vector questionList; public static String xmlFile; public XMLParser() { questionList = new Vector(); } public void parseXMl() throws SAXException, IOException, ParserConfigurationException { // Build a document based on the XML file. DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); DocumentBuilder builder = factory.newDocumentBuilder(); InputStream inputStream = getClass().getResourceAsStream(xmlFile); document = builder.parse(inputStream); } public void parseDocument() { Element element = document.getDocumentElement(); NodeList nl = element.getElementsByTagName("question"); if (nl != null && nl.getLength() > 0) { for (int i = 0; i < nl.getLength(); i++) { Element ele = (Element) nl.item(i); Question question = getQuestions(ele); questionList.addElement(question); } } } private Question getQuestions(Element element) { String title = getTextValue(element, "title"); String choice1 = getTextValue(element, "choice1"); String choice2 = getTextValue(element, "choice2"); String choice3 = getTextValue(element, "choice3"); String choice4 = getTextValue(element, "choice4"); String answer = getTextValue(element, "answer"); String rationale = getTextValue(element, "rationale"); Question Questions = new Question(title, choice1, choice2, choice3, choice4, answer, rationale); return Questions; } private String getTextValue(Element ele, String tagName) { String textVal = null; NodeList nl = ele.getElementsByTagName(tagName); if (nl != null && nl.getLength() > 0) { Element el = (Element) nl.item(0); textVal = el.getFirstChild().getNodeValue(); } return textVal; } } Nw the code for AppMain class //#preprocess package com.firstBooks.series79; import net.rim.device.api.ui.UiApplication; import com.firstBooks.series.ui.screens.HomeScreen; public class AppMain extends UiApplication { public static String _xmlFileName; public static boolean _Lite; public static int _totalNumofQuestions; public static void initialize(){ //#ifndef FULL /* //#endif _xmlFileName = "/res/Series79_FULL.xml"; _totalNumofQuestions = 50; _Lite = false; //#ifndef FULL */ //#endif //#ifndef LITE /* //#endif _xmlFileName = "/res/Series79_LITE.xml"; _totalNumofQuestions = 10; _Lite = true; //#ifndef LITE */ //#endif } private AppMain() { initialize(); pushScreen(new HomeScreen()); } public static void main(String args[]) { new AppMain().enterEventDispatcher(); } }

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  • BizTalk: History of one project architecture

    - by Leonid Ganeline
    "In the beginning God made heaven and earth. Then he started to integrate." At the very start was the requirement: integrate two working systems. Small digging up: It was one system. It was good but IT guys want to change it to the new one, much better, chipper, more flexible, and more progressive in technologies, more suitable for the future, for the faster world and hungry competitors. One thing. One small, little thing. We cannot turn off the old system (call it A, because it was the first), turn on the new one (call it B, because it is second but not the last one). The A has a hundreds users all across a country, they must study B. A still has a lot nice custom features, home-made features that cannot disappear. These features have to be moved to the B and it is a long process, months and months of redevelopment. So, the decision was simple. Let’s move not jump, let’s both systems working side-by-side several months. In this time we could teach the users and move all custom A’s special functionality to B. That automatically means both systems should work side-by-side all these months and use the same data. Data in A and B must be in sync. That’s how the integration projects get birth. Moreover, the specific of the user tasks requires the both systems must be in sync in real-time. Nightly synchronization is not working, absolutely.   First draft The first draft seems simple. Both systems keep data in SQL databases. When data changes, the Create, Update, Delete operations performed on the data, and the sync process could be started. The obvious decision is to use triggers on tables. When we are talking about data, we are talking about several entities. For example, Orders and Items [in Orders]. We decided to use the BizTalk Server to synchronize systems. Why it was chosen is another story. Second draft   Let’s take an example how it works in more details. 1.       User creates a new entity in the A system. This fires an insert trigger on the entity table. Trigger has to pass the message “Entity created”. This message includes all attributes of the new entity, but I focused on the Id of this entity in the A system. Notation for this message is id.A. System A sends id.A to the BizTalk Server. 2.       BizTalk transforms id.A to the format of the system B. This is easiest part and I will not focus on this kind of transformations in the following text. The message on the picture is still id.A but it is in slightly different format, that’s why it is changing in color. BizTalk sends id.A to the system B. 3.       The system B creates the entity on its side. But it uses different id-s for entities, these id-s are id.B. System B saves id.A+id.B. System B sends the message id.A+id.B back to the BizTalk. 4.       BizTalk sends the message id.A+id.B to the system A. 5.       System A saves id.A+id.B. Why both id-s should be saved on both systems? It was one of the next requirements. Users of both systems have to know the systems are in sync or not in sync. Users working with the entity on the system A can see the id.B and use it to switch to the system B and work there with the copy of the same entity. The decision was to store the pairs of entity id-s on both sides. If there is only one id, the entities are not in sync yet (for the Create operation). Third draft Next problem was the reliability of the synchronization. The synchronizing process can be interrupted on each step, when message goes through the wires. It can be communication problem, timeout, temporary shutdown one of the systems, the second system cannot be synchronized by some internal reason. There were several potential problems that prevented from enclosing the whole synchronization process in one transaction. Decision was to restart the whole sync process if it was not finished (in case of the error). For this purpose was created an additional service. Let’s call it the Resync service. We still keep the id pairs in both systems, but only for the fast access not for the synchronization process. For the synchronizing these id-s now are kept in one main place, in the Resync service database. The Resync service keeps record as: ·       Id.A ·       Id.B ·       Entity.Type ·       Operation (Create, Update, Delete) ·       IsSyncStarted (true/false) ·       IsSyncFinished (true/false0 The example now looks like: 1.       System A creates id.A. id.A is saved on the A. Id.A is sent to the BizTalk. 2.       BizTalk sends id.A to the Resync and to the B. id.A is saved on the Resync. 3.       System B creates id.B. id.A+id.B are saved on the B. id.A+id.B are sent to the BizTalk. 4.       BizTalk sends id.A+id.B to the Resync and to the A. id.A+id.B are saved on the Resync. 5.       id.A+id.B are saved on the B. Resync changes the IsSyncStarted and IsSyncFinished flags accordingly. The Resync service implements three main methods: ·       Save (id.A, Entity.Type, Operation) ·       Save (id.A, id.B, Entity.Type, Operation) ·       Resync () Two Save() are used to save id-s to the service storage. See in the above example, in 2 and 4 steps. What about the Resync()? It is the method that finishes the interrupted synchronization processes. If Save() is started by the trigger event, the Resync() is working as an independent process. It periodically scans the Resync storage to find out “unfinished” records. Then it restarts the synchronization processes. It tries to synchronize them several times then gives up.     One more thing, both systems A and B must tolerate duplicates of one synchronizing process. Say on the step 3 the system B was not able to send id.A+id.B back. The Resync service must restart the synchronization process that will send the id.A to B second time. In this case system B must just send back again also created id.A+id.B pair without errors. That means “tolerate duplicates”. Fourth draft Next draft was created only because of the aesthetics. As it always happens, aesthetics gave significant performance gain to the whole system. First was the stupid question. Why do we need this additional service with special database? Can we just master the BizTalk to do something like this Resync() does? So the Resync orchestration is doing the same thing as the Resync service. It is started by the Id.A and finished by the id.A+id.B message. The first works as a Start message, the second works as a Finish message.     Here is a diagram the whole process without errors. It is pretty straightforward. The Resync orchestration is waiting for the Finish message specific period of time then resubmits the Id.A message. It resubmits the Id.A message specific number of times then gives up and gets suspended. It can be resubmitted then it starts the whole process again: waiting [, resubmitting [, get suspended]], finishing. Tuning up The Resync orchestration resubmits the id.A message with special “Resubmitted” flag. The subscription filter on the Resync orchestration includes predicate as (Resubmit_Flag != “Resubmitted”). That means only the first Sync orchestration starts the Resync orchestration. Other Sync orchestration instantiated by the resubmitting can finish this Resync orchestration but cannot start another instance of the Resync   Here is a diagram where system B was inaccessible for some period of time. The Resync orchestration resubmitted the id.A two times. Then system B got the response the id.A+id.B and this finished the Resync service execution. What is interesting about this, there were submitted several identical id.A messages and only one id.A+id.B message. Because of this, the system B and the Resync must tolerate the duplicate messages. We also told about this requirement for the system B. Now the same requirement is for the Resunc. Let’s assume the system B was very slow in the first response and the Resync service had time to resubmit two id.A messages. System B responded not, as it was in previous case, with one id.A+id.B but with two id.A+id.B messages. First of them finished the Resync execution for the id.A. What about the second id.A+id.B? Where it goes? So, we have to add one more internal requirement. The whole solution must tolerate many identical id.A+id.B messages. It is easy task with the BizTalk. I added the “SinkExtraMessages” subscriber (orchestration with one receive shape), that just get these messages and do nothing. Real design Real architecture is much more complex and interesting. In reality each system can submit several id.A almost simultaneously and completely unordered. There are not only the “Create entity” operation but the Update and Delete operations. And these operations relate each other. Say the Update operation after Delete means not the same as Update after Create. In reality there are entities related each other. Say the Order and Order Items. Change on one of it could start the series of the operations on another. Moreover, the system internals are the “black boxes” and we cannot predict the exact content and order of the operation series. It worth to say, I had to spend a time to manage the zombie message problems. The zombies are still here, but this is not a problem now. And this is another story. What is interesting in the last design? One orchestration works to help another to be more reliable. Why two orchestration design is more reliable, isn’t it something strange? The Synch orchestration takes all the message exchange between systems, here is the area where most of the errors could happen. The Resync orchestration sends and receives messages only within the BizTalk server. Is there another design? Sure. All Resync functionality could be implemented inside the Sync orchestration. Hey guys, some other ideas?

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  • Regex one-to-one mapping pattern replace

    - by polygenelubricants
    How would you use regex to write a function that replaces all lowercase letters with uppercase and vice versa? Note: this is NOT a homework question. See also my previous explorations of regex: Regex split into overlapping strings (Alan Moore's answer is especially instructive) Can you use zero-width matching regex in String split? (my solution exploits a known Java regex bug with regards to non-obvious length lookbehind!)

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