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• Stumbling Through: Visual Studio 2010 (Part II)

  I would now like to expand a little on what I stumbled through in part I of my Visual Studio 2010 post and touch on a few other features of VS 2010.  Specifically, I want to generate some code based off of an Entity Framework model and tie it up to an actual data source.  Im not going to take the easy way and tie to a SQL Server data source, though, I will tie it to an XML data file instead.  Why?  Well, why not?  This is purely for learning, there are probably much better ways to get strongly-typed classes around XML but it will force us to go down a path less travelled and maybe learn a few things along the way.  Once we get this XML data and the means to interact with it, I will revisit data binding to this data in a WPF form and see if I cant get reading, adding, deleting, and updating working smoothly with minimal code.  To begin, I will use what was learned in the first part of this blog topic and draw out a data model for the MFL (My Football League) - I dont want the NFL to come down and sue me for using their name in this totally football-related article.  The data model looks as follows, with Teams having Players, and Players having a position and statistics for each season they played: Note that when making the associations between these entities, I was given the option to create the foreign key but I only chose to select this option for the association between Player and Position.  The reason for this is that I am picturing the XML that will contain this data to look somewhat like this: <MFL> <Position/> <Position/> <Position/> <Team>     <Player>         <Statistic/>     </Player> </Team> </MFL> Statistic will be under its associated Player node, and Player will be under its associated Team node no need to have an Id to reference it if we know it will always fall under its parent.  Position, however, is more of a lookup value that will not have any hierarchical relationship to the player.  In fact, the Position data itself may be in a completely different xml file (something Id like to play around with), so in any case, a player will need to reference the position by its Id. So now that we have a simple data model laid out, I would like to generate two things based on it:  A class for each entity with properties corresponding to each entity property An IO class with methods to get data for each entity, either all instances, by Id or by parent. Now my experience with code generation in the past has consisted of writing up little apps that use the code dom directly to regenerate code on demand (or using tools like CodeSmith).  Surely, there has got to be a more fun way to do this given that we are using the Entity Framework which already has built-in code generation for SQL Server support.  Lets start with that built-in stuff to give us a base to work off of.  Right click anywhere in the canvas of our model and select Add Code Generation Item: So just adding that code item seemed to do quite a bit towards what I was intending: It apparently generated a class for each entity, but also a whole ton more.  I mean a TON more.  Way too much complicated code was generated now that code is likely to be a black box anyway so it shouldnt matter, but we need to understand how to make this work the way we want it to work, so lets get ready to do some stumbling through that text template (tt) file. When I open the .tt file that was generated, right off the bat I realize there is going to be trouble there is no color coding, no intellisense no nothing!  That is going to make stumbling through more like groping blindly in the dark while handcuffed and hopping on one foot, which was one of the alternate titles I was considering for this blog.  Thankfully, the community comes to my rescue and I wont have to cast my mind back to the glory days of coding in VI (look it up, kids).  Using the Extension Manager (Available under the Tools menu), I did a quick search for tt editor in the Online Gallery and quickly found the Tangible T4 Editor: Downloading and installing this was a breeze, and after doing so I got some color coding and intellisense while editing the tt files.  If you will be doing any customizing of tt files, I highly recommend installing this extension.  Next, well see if that is enough help for us to tweak that tt file to do the kind of code generation that we wantDid you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Stumbling Through: Visual Studio 2010 (Part II)

  I would now like to expand a little on what I stumbled through in part I of my Visual Studio 2010 post and touch on a few other features of VS 2010.  Specifically, I want to generate some code based off of an Entity Framework model and tie it up to an actual data source.  Im not going to take the easy way and tie to a SQL Server data source, though, I will tie it to an XML data file instead.  Why?  Well, why not?  This is purely for learning, there are probably much better ways to get strongly-typed classes around XML but it will force us to go down a path less travelled and maybe learn a few things along the way.  Once we get this XML data and the means to interact with it, I will revisit data binding to this data in a WPF form and see if I cant get reading, adding, deleting, and updating working smoothly with minimal code.  To begin, I will use what was learned in the first part of this blog topic and draw out a data model for the MFL (My Football League) - I dont want the NFL to come down and sue me for using their name in this totally football-related article.  The data model looks as follows, with Teams having Players, and Players having a position and statistics for each season they played: Note that when making the associations between these entities, I was given the option to create the foreign key but I only chose to select this option for the association between Player and Position.  The reason for this is that I am picturing the XML that will contain this data to look somewhat like this: <MFL> <Position/> <Position/> <Position/> <Team>     <Player>         <Statistic/>     </Player> </Team> </MFL> Statistic will be under its associated Player node, and Player will be under its associated Team node no need to have an Id to reference it if we know it will always fall under its parent.  Position, however, is more of a lookup value that will not have any hierarchical relationship to the player.  In fact, the Position data itself may be in a completely different xml file (something Id like to play around with), so in any case, a player will need to reference the position by its Id. So now that we have a simple data model laid out, I would like to generate two things based on it:  A class for each entity with properties corresponding to each entity property An IO class with methods to get data for each entity, either all instances, by Id or by parent. Now my experience with code generation in the past has consisted of writing up little apps that use the code dom directly to regenerate code on demand (or using tools like CodeSmith).  Surely, there has got to be a more fun way to do this given that we are using the Entity Framework which already has built-in code generation for SQL Server support.  Lets start with that built-in stuff to give us a base to work off of.  Right click anywhere in the canvas of our model and select Add Code Generation Item: So just adding that code item seemed to do quite a bit towards what I was intending: It apparently generated a class for each entity, but also a whole ton more.  I mean a TON more.  Way too much complicated code was generated now that code is likely to be a black box anyway so it shouldnt matter, but we need to understand how to make this work the way we want it to work, so lets get ready to do some stumbling through that text template (tt) file. When I open the .tt file that was generated, right off the bat I realize there is going to be trouble there is no color coding, no intellisense no nothing!  That is going to make stumbling through more like groping blindly in the dark while handcuffed and hopping on one foot, which was one of the alternate titles I was considering for this blog.  Thankfully, the community comes to my rescue and I wont have to cast my mind back to the glory days of coding in VI (look it up, kids).  Using the Extension Manager (Available under the Tools menu), I did a quick search for tt editor in the Online Gallery and quickly found the Tangible T4 Editor: Downloading and installing this was a breeze, and after doing so I got some color coding and intellisense while editing the tt files.  If you will be doing any customizing of tt files, I highly recommend installing this extension.  Next, well see if that is enough help for us to tweak that tt file to do the kind of code generation that we wantDid you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Stumbling Through: Visual Studio 2010 (Part III)

  The last post ended with us just getting started on stumbling into text template file customization, a task that required a Visual Studio extension (Tangible T4 Editor) to even have a chance at completing.  Despite the benefits of the Tangible T4 Editor, I still had a hard time putting together a solid text template that would be easy to explain.  This is mostly due to the way the files allow you to mix code (encapsulated in <# #>) with straight-up text to generate.  It is effective to be sure, but not very readable.  Nevertheless, I will try and explain what was accomplished in my custom tt file, though the details of which are not really the point of this article (my way of saying dont criticize my crappy code, and certainly dont use it in any somewhat real application.  You may become dumber just by looking at this code.  You have been warned really the footnote I should put at the end of all of my blog posts). To begin with, there were two basic requirements that I needed the code generator to satisfy:  Reading one to many entity framework files, and using the entities that were found to write one to many class files.  Thankfully, using the Entity Object Generator as a starting point gave us an example on how to do exactly that by using the MetadataLoader and EntityFrameworkTemplateFileManager you include references to these items and use them like so: // Instantiate an entity framework file reader and file writer MetadataLoader loader = new MetadataLoader(this); EntityFrameworkTemplateFileManager fileManager = EntityFrameworkTemplateFileManager.Create(this); // Load the entity model metadata workspace MetadataWorkspace metadataWorkspace = null; bool allMetadataLoaded =loader.TryLoadAllMetadata("MFL.tt", out metadataWorkspace); EdmItemCollection ItemCollection = (EdmItemCollection)metadataWorkspace.GetItemCollection(DataSpace.CSpace); // Create an IO class to contain the 'get' methods for all entities in the model fileManager.StartNewFile("MFL.IO.gen.cs"); Next, we want to be able to loop through all of the entities found in the model, and then each property for each entity so we can generate classes and methods for each.  The code for that is blissfully simple: // Iterate through each entity in the model foreach (EntityType entity in ItemCollection.GetItems<EntityType>().OrderBy(e => e.Name)) {     // Iterate through each primitive property of the entity     foreach (EdmProperty edmProperty in entity.Properties.Where(p => p.TypeUsage.EdmType is PrimitiveType && p.DeclaringType == entity))     {         // TODO:  Create properties     }     // Iterate through each relationship of the entity     foreach (NavigationProperty navProperty in entity.NavigationProperties.Where(np => np.DeclaringType == entity))     {         // TODO:  Create associations     } } There really isnt anything more advanced than that going on in the text template the only thing I had to blunder through was realizing that if you want the generator to interpret a line of code (such as our iterations above), you need to enclose the code in <# and #> while if you want the generator to interpret the VALUE of code, such as putting the entity name into the class name, you need to enclose the code in <#= and #> like so: public partial class <#=entity.Name#> To make a long story short, I did a lot of repetition of the above to come up with a text template that generates a class for each entity based on its properties, and a set of IO methods for each entity based on its relationships.  The two work together to provide lazy-loading for hierarchical data (such getting Team.Players) so it should be pretty intuitive to use on a front-end.  This text template is available here you can tweak the inputFiles array to load one or many different edmx models and generate the basic xml IO and class files, though it will probably only work correctly in the simplest of cases, like our MFL model described in the previous post.  Additionally, there is no validation, logging or error handling which is something I want to handle later by stumbling through the enterprise library 5.0. The code that gets generated isnt anything special, though using the LINQ to XML feature was something very new and exciting for me I had only worked with XML in the past using the DOM or XML Reader objects along with XPath, and the LINQ to XML model is just so much more elegant and supposedly efficient (something to test later).  For example, the following code was generated to create a Player object for each Player node in the XML:         return from element in GetXmlData(_PlayerDataFile).Descendants("Player")             select new Player             {                 Id = int.Parse(element.Attribute("Id").Value)                 ,ParentName = element.Parent.Name.LocalName                 ,ParentId = long.Parse(element.Parent.Attribute("Id").Value)                 ,Name = element.Attribute("Name").Value                 ,PositionId = int.Parse(element.Attribute("PositionId").Value)             }; It is all done in one line of code, no looping needed.  Even though GetXmlData loads the entire xml file just like the old XML DOM approach would have, it is supposed to be much less resource intensive.  I will definitely put that to the test after we develop a user interface for getting at this data.  Speaking of the data where IS the data?  Weve put together a pretty model and a bunch of code around it, but we dont have any data to speak of.  We can certainly drop to our favorite XML editor and crank out some data, but if it doesnt totally match our model, it will not load correctly.  To help with this, Ive built in a method to generate xml at any given layer in the hierarchy.  So for us to get the closest possible thing to real data, wed need to invoke MFL.IO.GenerateTeamXML and save the results to file.  Doing so should get us something that looks like this: <Team Id="0" Name="0">   <Player Id="0" Name="0" PositionId="0">     <Statistic Id="0" PassYards="0" RushYards="0" Year="0" />   </Player> </Team> Sadly, it is missing the Positions node (havent thought of a way to generate lookup xml yet) and the data itself isnt quite realistic (well, as realistic as MFL data can be anyway).  Lets manually remedy that for now to give us a decent starter set of data.  Note that this is TWO xml files Lookups.xml and Teams.xml: <Lookups Id=0>   <Position Id="0" Name="Quarterback"/>   <Position Id="1" Name="Runningback"/> </Lookups> <Teams Id=0>   <Team Id="0" Name="Chicago">     <Player Id="0" Name="QB Bears" PositionId="0">       <Statistic Id="0" PassYards="4000" RushYards="120" Year="2008" />       <Statistic Id="1" PassYards="4200" RushYards="180" Year="2009" />     </Player>     <Player Id="1" Name="RB Bears" PositionId="1">       <Statistic Id="2" PassYards="0" RushYards="800" Year="2007" />       <Statistic Id="3" PassYards="0" RushYards="1200" Year="2008" />       <Statistic Id="4" PassYards="3" RushYards="1450" Year="2009" />     </Player>   </Team> </Teams> Ok, so we have some data, we have a way to read/write that data and we have a friendly way of representing that data.  Now, what remains is the part that I have been looking forward to the most: present the data to the user and give them the ability to add/update/delete, and doing so in a way that is very intuitive (easy) from a development standpoint.Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

  Read the article

• Stumbling Through: Visual Studio 2010 (Part III)

  The last post ended with us just getting started on stumbling into text template file customization, a task that required a Visual Studio extension (Tangible T4 Editor) to even have a chance at completing.  Despite the benefits of the Tangible T4 Editor, I still had a hard time putting together a solid text template that would be easy to explain.  This is mostly due to the way the files allow you to mix code (encapsulated in <# #>) with straight-up text to generate.  It is effective to be sure, but not very readable.  Nevertheless, I will try and explain what was accomplished in my custom tt file, though the details of which are not really the point of this article (my way of saying dont criticize my crappy code, and certainly dont use it in any somewhat real application.  You may become dumber just by looking at this code.  You have been warned really the footnote I should put at the end of all of my blog posts). To begin with, there were two basic requirements that I needed the code generator to satisfy:  Reading one to many entity framework files, and using the entities that were found to write one to many class files.  Thankfully, using the Entity Object Generator as a starting point gave us an example on how to do exactly that by using the MetadataLoader and EntityFrameworkTemplateFileManager you include references to these items and use them like so: // Instantiate an entity framework file reader and file writer MetadataLoader loader = new MetadataLoader(this); EntityFrameworkTemplateFileManager fileManager = EntityFrameworkTemplateFileManager.Create(this); // Load the entity model metadata workspace MetadataWorkspace metadataWorkspace = null; bool allMetadataLoaded =loader.TryLoadAllMetadata("MFL.tt", out metadataWorkspace); EdmItemCollection ItemCollection = (EdmItemCollection)metadataWorkspace.GetItemCollection(DataSpace.CSpace); // Create an IO class to contain the 'get' methods for all entities in the model fileManager.StartNewFile("MFL.IO.gen.cs"); Next, we want to be able to loop through all of the entities found in the model, and then each property for each entity so we can generate classes and methods for each.  The code for that is blissfully simple: // Iterate through each entity in the model foreach (EntityType entity in ItemCollection.GetItems<EntityType>().OrderBy(e => e.Name)) {     // Iterate through each primitive property of the entity     foreach (EdmProperty edmProperty in entity.Properties.Where(p => p.TypeUsage.EdmType is PrimitiveType && p.DeclaringType == entity))     {         // TODO:  Create properties     }     // Iterate through each relationship of the entity     foreach (NavigationProperty navProperty in entity.NavigationProperties.Where(np => np.DeclaringType == entity))     {         // TODO:  Create associations     } } There really isnt anything more advanced than that going on in the text template the only thing I had to blunder through was realizing that if you want the generator to interpret a line of code (such as our iterations above), you need to enclose the code in <# and #> while if you want the generator to interpret the VALUE of code, such as putting the entity name into the class name, you need to enclose the code in <#= and #> like so: public partial class <#=entity.Name#> To make a long story short, I did a lot of repetition of the above to come up with a text template that generates a class for each entity based on its properties, and a set of IO methods for each entity based on its relationships.  The two work together to provide lazy-loading for hierarchical data (such getting Team.Players) so it should be pretty intuitive to use on a front-end.  This text template is available here you can tweak the inputFiles array to load one or many different edmx models and generate the basic xml IO and class files, though it will probably only work correctly in the simplest of cases, like our MFL model described in the previous post.  Additionally, there is no validation, logging or error handling which is something I want to handle later by stumbling through the enterprise library 5.0. The code that gets generated isnt anything special, though using the LINQ to XML feature was something very new and exciting for me I had only worked with XML in the past using the DOM or XML Reader objects along with XPath, and the LINQ to XML model is just so much more elegant and supposedly efficient (something to test later).  For example, the following code was generated to create a Player object for each Player node in the XML:         return from element in GetXmlData(_PlayerDataFile).Descendants("Player")             select new Player             {                 Id = int.Parse(element.Attribute("Id").Value)                 ,ParentName = element.Parent.Name.LocalName                 ,ParentId = long.Parse(element.Parent.Attribute("Id").Value)                 ,Name = element.Attribute("Name").Value                 ,PositionId = int.Parse(element.Attribute("PositionId").Value)             }; It is all done in one line of code, no looping needed.  Even though GetXmlData loads the entire xml file just like the old XML DOM approach would have, it is supposed to be much less resource intensive.  I will definitely put that to the test after we develop a user interface for getting at this data.  Speaking of the data where IS the data?  Weve put together a pretty model and a bunch of code around it, but we dont have any data to speak of.  We can certainly drop to our favorite XML editor and crank out some data, but if it doesnt totally match our model, it will not load correctly.  To help with this, Ive built in a method to generate xml at any given layer in the hierarchy.  So for us to get the closest possible thing to real data, wed need to invoke MFL.IO.GenerateTeamXML and save the results to file.  Doing so should get us something that looks like this: <Team Id="0" Name="0">   <Player Id="0" Name="0" PositionId="0">     <Statistic Id="0" PassYards="0" RushYards="0" Year="0" />   </Player> </Team> Sadly, it is missing the Positions node (havent thought of a way to generate lookup xml yet) and the data itself isnt quite realistic (well, as realistic as MFL data can be anyway).  Lets manually remedy that for now to give us a decent starter set of data.  Note that this is TWO xml files Lookups.xml and Teams.xml: <Lookups Id=0>   <Position Id="0" Name="Quarterback"/>   <Position Id="1" Name="Runningback"/> </Lookups> <Teams Id=0>   <Team Id="0" Name="Chicago">     <Player Id="0" Name="QB Bears" PositionId="0">       <Statistic Id="0" PassYards="4000" RushYards="120" Year="2008" />       <Statistic Id="1" PassYards="4200" RushYards="180" Year="2009" />     </Player>     <Player Id="1" Name="RB Bears" PositionId="1">       <Statistic Id="2" PassYards="0" RushYards="800" Year="2007" />       <Statistic Id="3" PassYards="0" RushYards="1200" Year="2008" />       <Statistic Id="4" PassYards="3" RushYards="1450" Year="2009" />     </Player>   </Team> </Teams> Ok, so we have some data, we have a way to read/write that data and we have a friendly way of representing that data.  Now, what remains is the part that I have been looking forward to the most: present the data to the user and give them the ability to add/update/delete, and doing so in a way that is very intuitive (easy) from a development standpoint.Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

  Read the article

• Stumbling Through: Visual Studio 2010 (Part I)

  Ive spent the better part of the last two years doing nothing but K2 workflow development, which until very recently could only be done in Visual Studio 2005 so I am a bit behind the times. I seem to have skipped over using Visual Studio 2008 entirely, and I am now ready to stumble through all that Ive missed. Not that I will abandon my K2 ramblings, but I need to get back to some of the other technologies I am passionate about but havent had the option of working with them on a day-to-day basis as I have with K2 blackpearl. Specifically, I am going to be focusing my efforts on what is new in the Entity Framework and WPF in Visual Studio 2010, though you have to keep in mind that since I have skipped VS 2008, I may be giving VS 2010 credit for things that really have been around for a while (hey, if I havent seen it, it is new to me!). I have the following simple goals in mind for this exercise: Entity Framework Model an inherited class Entity Framework Model a lookup entity WPF Bind a list of entities WPF - on selection of an entity in the bound list, display values of the selected entity WPF For the lookup field, provide a dropdown of potential values to lookup All of these goals must be accomplished using as little code as possible, relying on the features we get out of the box in Visual Studio 2010. This isnt going to be rocket science here, Im not even looking to get or save this data from/to a data source, but I gotta start somewhere and hopefully it will grow into something more interesting. For this exercise, I am going to try to model some fictional data about football players and personnel (maybe turning this into some sort of NFL simulation game if I lose my job and can play with this all day), so Ill start with a Person class that has a name property, and extend that with a Player class to include a Position lookup property. The idea is that a Person can be a Player, Coach or whatever other personnel type may be associated with a football team but well only flesh out the Player aspect of a person for this. So to get started, I fired up Visual Studio 2010 and created a new WPF Application: To this project, I added a new ADO.NET Entity Data Model named PlayerModel (for now, not sure what will be an appropriate name so this may be revisited): I chose for it to be an empty model, as I dont have a database designed for this yet: Using the toolbox, I dragged out an entity for each of the items we identified earlier: Person, Player and Position, and gave them some simple properties (note that I kept the default Id property for each of them): Now to figure out how to link these things together the way I want to first, lets try to tell it that Player extends Person. I see that Inheritance is one of the items in the toolbox, but I cant seem to drag it out anywhere onto the canvas. However, when I right-click an element, I get the option to Add Inheritance to it, which gives us exactly what we want: Ok, now that we have that, how do we tell it that each player has a position? Well, despite association being in the toolbox, I have learned that you cant just drag and drop those elements so I right click Player and select Add -> Association to get the following dialog: I see the option here to Add foreign key properties to my entities Ive read somewhere this this is a new and highly-sought after feature so Ill see what it does. Selecting it includes a PositionId on the Player element for me, which seems pretty database-centric and I would like to see if I can live without it for now given that we also got the Position property out of this association. Ill bring it back into the fold if it ends up being useful later. Here is what we end up with now: Trying to compile this resulted in an error stating that the Player entity cannot have an Id, because the Person element it extends already has a property named Id. Makes sense, so I remove it and compile again. Success, but with a warning but success is a good thing so Ill pretend I didnt see that warning for now. It probably has to do with the fact that my Player entity is now pretty useless as it doesnt have any non-navigation properties. So things seem to match what we are going for, great now what the heck do we do with this? Lets switch gears and see what we get for free dealing with this model from the UI. Lets open up the MainWindow.xaml and see if we can connect to our entities as a data source. Hey, whats this? Have you read my mind, Visual Studio? Our entities are already listed in the Data Sources panel: I do notice, however, that our Player entity is missing. Is this due to that compilation warning? Ill add a bogus property to our player entity just to see if that is the case no, still no love. The warning reads: Error 2062: No mapping specified for instances of the EntitySet and AssociationSet in the EntityContainer PlayerModelContainer. Well if everything worked without any issues, then I wouldnt be stumbling through at all, so lets get to the bottom of this. My good friend google indicates that the warning is due to the model not being tied up to a database. Hmmm, so why dont Players show up in my data sources? A little bit of drill-down shows that they are, in fact, exposed under Positions: Well now that isnt quite what I want. While you could get to players through a position, it shouldnt be that way exclusively. Oh well, I can ignore that for now lets drag Players out onto the canvas after selecting List from the dropdown: Hey, what the heck? I wanted a list not a listview. Get rid of that list view that was just dropped, drop in a listbox and then drop the Players entity into it. That will bind it for us. Of course, there isnt any data to show, which brings us to the really hacky part of all this and that is to stuff some test data into our view source without actually getting it from any data source. To do this through code, we need to grab a reference to the positionsPlayersViewSource resource that was created for us when we dragged out our Players entity. We then set the source of that reference equal to a populated list of Players.  Well add a couple of players that way as well as a few positions via the positionsViewSource resource, and Ill ensure that each player has a position specified.  Ultimately, the code looks like this: System.Windows.Data.CollectionViewSource positionViewSource = ((System.Windows.Data.CollectionViewSource)(this.FindResource("positionsViewSource")));             List<Position> positions = new List<Position>();             Position newPosition = new Position();             newPosition.Id = 0;             newPosition.Name = "WR";             positions.Add(newPosition);             newPosition = new Position();             newPosition.Id = 1;             newPosition.Name = "RB";             positions.Add(newPosition);             newPosition = new Position();             newPosition.Id = 2;             newPosition.Name = "QB";             positions.Add(newPosition);             positionViewSource.Source = positions;             System.Windows.Data.CollectionViewSource playerViewSource = ((System.Windows.Data.CollectionViewSource)(this.FindResource("positionsPlayersViewSource")));             List<Player> players = new List<Player>();             Player newPlayer = new Player();             newPlayer.Id = 0;             newPlayer.Name = "Test Dude";             newPlayer.Position = positions[0];             players.Add(newPlayer);             newPlayer = new Player();             newPlayer.Id = 1;             newPlayer.Name = "Test Dude II";             newPlayer.Position = positions[1];             players.Add(newPlayer);             newPlayer = new Player();             newPlayer.Id = 2;             newPlayer.Name = "Test Dude III";             newPlayer.Position = positions[2];             players.Add(newPlayer);             playerViewSource.Source = players; Now that our views are being loaded with data, we can go about tying things together visually. Drop a text box (to show the selected players name) and a combo box (to show the selected players position). Drag the Positions entity from the data sources panel to the combo box to wire it up to the positions view source. Click the text box that was dragged, and find its Text property in the properties pane. There is a little glyph next to it that displays Advanced Properties when hovered over click this and then select Apply Data Binding. In the dialog that appears, we can select the current players name as the value to bind to: Similarly, we can wire up the combo boxs SelectedItem value to the current players position: When the application is executed and we navigate through the various players, we automatically get their name and position bound to the appropriate fields: All of this was accomplished with no code save for loading the test data, and I might add, it was pretty intuitive to do so via the drag and drop of entities straight from the data sources panel. So maybe all of this was old hat to you, but I was very impressed with this experience and I look forward to stumbling through the caveats of doing more complex data modeling and binding in this fashion. Next up, I suppose, will be figuring out how to get the entities to get real data from a data source instead of stuffing it with test data as well as trying to figure out why Players ended up being under Positions in the data sources panel.Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Stumbling Through: Making a case for the K2 Case Management Framework

  I have recently attended a three-day training session on K2s Case Management Framework (CMF), a free framework built on top of K2s blackpearl workflow product, and I have come away with several different impressions for some of the different aspects of the framework.  Before we get into the details, what is the Case Management Framework?  It is essentially a suite of tools that, when used together, solve many common workflow scenarios.  The tool has been developed over time by K2 consultants that have realized they tend to solve the same problems over and over for various clients, so they attempted to package all of those common solutions into one framework.  Most of these common problems involve workflow process that arent necessarily direct and would tend to be difficult to model.  Such solutions could be achieved in blackpearl alone, but the workflows would be complex and difficult to follow and maintain over time.  CMF attempts to simplify such scenarios not so much by black-boxing the workflow processes, but by providing different points of entry to the processes allowing them to be simpler, moving the complexity to a middle layer.  It is not a solution in and of itself, development is still required to tie the pieces together. CMF is under continuous development, both a plus and a minus in that bugs are fixed quickly and features added regularly, but it may be difficult to know which versions are the most stable.  CMF is not an officially supported K2 product, which means you will not get technical support but you will get access to the source code. The example given of a business process that would fit well into CMF is that of a file cabinet, where each folder in said file cabinet is a case that contains all of the data associated with one complaint/customer/incident/etc. and various users can access that case at any time and take one of a set of pre-determined actions on it.  When I was given that example, my first thought was that any workflow I have ever developed in the past could be made to fit this model there must be more than just this model to help decide if CMF is the right solution.  As the training went on, we learned that one of the key features of CMF is SharePoint integration as each case gets a SharePoint site created for it, and there are a number of excellent web parts that can be used to design a portal for users to get at all the information on their cases.  While CMF does not require SharePoint, without it you will be missing out on a huge portion of functionality that CMF offers.  My opinion is that without SharePoint integration, you may as well write your workflows and other components the old fashioned way. When I heard that each case gets its own SharePoint site created for it, warning bells immediately went off in my head as I felt that depending on the data load, a CMF enabled solution could quickly overwhelm SharePoint with thousands of sites so we have yet another deciding factor for CMF:  Just how many cases will your solution be creating?  While it is not necessary to use the site-per-case model, it is one of the more useful parts of the framework.  Without it, you are losing a big chunk of what CMF has to offer. When it comes to developing on top of the Case Management Framework, it becomes a matter of configuring what makes up a case, what can be done to a case, where each action on a case should take the user, and then typing up actions to case statuses.  This last step is one that I immediately warmed up to, as just about every workflow Ive designed in the past needed some sort of mapping table to set the status of a work item based on the action being taken definitely one of those common solutions that it is good to see rolled up into a re-useable entity (and it gets a nice configuration UI to boot!).  This concept is a little different than traditional workflow design, in that you dont have to think of an end-to-end process around passing a case along a path, rather, you must envision the case as central object with workflow threads branching off of it and doing their own thing with the case data.  Certainly there can be certain workflow threads that get rather complex, but the idea is that they RELATE to the case, they dont BECOME the case (though it is still possible with action->status mappings to prevent certain actions in certain cases, so it isnt always a wide-open free for all of actions on a case). I realize that this description of the Case Management Framework merely scratches the surface on what the product actually can do, and I dont think Ive conclusively defined for what sort of business scenario you can make a case for Case Management Framework.  What I do hope to have accomplished with this post is to raise awareness of CMF there is a (free!) product out there that could potentially simplify a tangled workflow process and give (for free!) a very useful set of SharePoint web parts and a nice set of (free!) reports.  The best way to see if it will truly fit your needs is to give it a try did I mention it is FREE?  Er, ok, so it is free, but only obtainable at this time for K2 partnersDid you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Stumbling Through: Visual Studio 2010 (Part IV)

  So finally we get to the fun part the fruits of all of our middle-tier/back end labors of generating classes to interface with an XML data source that the previous posts were about can now be presented quickly and easily to an end user.  I think.  Well see.  Well be using a WPF window to display all of our various MFL information that weve collected in the two XML files, and well provide a means of adding, updating and deleting each of these entities using as little code as possible.  Additionally, I would like to dig into the performance of this solution as well as the flexibility of it if were were to modify the underlying XML schema.  So first things first, lets create a WPF project and include our xml data in a data folder within.  On the main window, well drag out the following controls: A combo box to contain all of the teams A list box to show the players of the selected team, along with add/delete player buttons A text box tied to the selected players name, with a save button to save any changes made to the player name A combo box of all the available positions, tied to the currently selected players position A data grid tied to the statistics of the currently selected player, with add/delete statistic buttons This monstrosity of a form and its associated project will look like this (dont forget to reference the DataFoundation project from the Presentation project): To get to the visual data binding, as we learned in a previous post, you have to first make sure the project containing your bindable classes is compiled.  Do so, and then open the Data Sources pane to add a reference to the Teams and Positions classes in the DataFoundation project: Why only Team and Position?  Well, we will get to Players from Teams, and Statistics from Players so no need to make an interface for them as well see in a second.  As for Positions, well need a way to bind the dropdown to ALL positions they dont appear underneath any of the other classes so we need to reference it directly.  After adding these guys, expand every node in your Data Sources pane and see how the Team node allows you to drill into Players and then Statistics.  This is why there was no need to bring in a reference to those classes for the UI we are designing: Now for the seriously hard work of binding all of our controls to the correct data sources.  Drag the following items from the Data Sources pane to the specified control on the window design canvas: Team.Name > Teams combo box Team.Players.Name > Players list box Team.Players.Name > Player name text box Team.Players.Statistics > Statistics data grid Position.Name > Positions combo box That is it!  Really?  Well, no, not really there is one caveat here in that the Positions combo box is not bound the selected players position.  To do so, we will apply a binding to the position combo boxs SelectedValue to point to the current players PositionId value: That should do the trick now, all we need to worry about is loading the actual data.  Sadly, it appears as if we will need to drop to code in order to invoke our IO methods to load all teams and positions.  At least Visual Studio kindly created the stubs for us to do so, ultimately the code should look like this: Note the weirdness with the InitializeDataFiles call that is my current means of telling an IO where to load the data for each of the entities.  I havent thought of a more intuitive way than that yet, but do note that all data is loaded from Teams.xml besides for positions, which is loaded from Lookups.xml.   I think that may be all we need to do to at least load all of the data, lets run it and see: Yay!  All of our glorious data is being displayed!  Er, wait, whats up with the position dropdown?  Why is it red?  Lets select the RB and see if everything updates: Crap, the position didnt update to reflect the selected player, but everything else did.  Where did we go wrong in binding the position to the selected player?  Thinking about it a bit and comparing it to how traditional data binding works, I realize that we never set the value member (or some similar property) to tell the control to join the Id of the source (positions) to the position Id of the player.  I dont see a similar property to that on the combo box control, but I do see a property named SelectedValuePath that might be it, so I set it to Id and run the app again: Hey, all right!  No red box around the positions combo box.  Unfortunately, selecting the RB does not update the dropdown to point to Runningback.  Hmmm.  Now what could it be?  Maybe the problem is that we are loading teams before we are loading positions, so when it binds position Id, all of the positions arent loaded yet.  I went to the code behind and switched things so position loads first and no dice.  Same result when I run.  Why?  WHY?  Ok, ok, calm down, take a deep breath.  Get something with caffeine or sugar (preferably both) and think rationally. Ok, gigantic chocolate chip cookie and a mountain dew chaser have never let me down in the past, so dont fail me now!  Ah ha!  of course!  I didnt even have to finish the mountain dew and I think Ive got it:  Data Context.  By default, when setting on the selected value binding for the dropdown, the data context was list_team.  I dont even know what the heck list_team is, we want it to be bound to our team players view source resource instead, like this: Running it now and selecting the various players: Done and done.  Everything read and bound, thank you caffeine and sugar!  Oh, and thank you Visual Studio 2010.  Lets wire up some of those buttons now There has got to be a better way to do this, but it works for now.  What the add player button does is add a new player object to the currently selected team.  Unfortunately, I couldnt get the new object to automatically show up in the players list (something about not using an observable collection gotta look into this) so I just save the change immediately and reload the screen.  Terrible, but it works: Lets go after something easier:  The save button.  By default, as we type in new text for the players name, it is showing up in the list box as updated.  Cool!  Why couldnt my add new player logic do that?  Anyway, the save button should be as simple as invoking MFL.IO.Save for the selected player, like this: MFL.IO.Save((MFL.Player)lbTeamPlayers.SelectedItem, true); Surprisingly, that worked on the first try.  Lets see if we get as lucky with the Delete player button: MFL.IO.Delete((MFL.Player)lbTeamPlayers.SelectedItem); Refresh(); Note the use of the Refresh method again I cant seem to figure out why updates to the underlying data source are immediately reflected, but adds and deletes are not.  That is a problem for another day, and again my hunch is that I should be binding to something more complex than IEnumerable (like observable collection). Now that an example of the basic CRUD methods are wired up, I want to quickly investigate the performance of this beast.  Im going to make a special button to add 30 teams, each with 50 players and 10 seasons worth of stats.  If my math is right, that will end up with 15000 rows of data, a pretty hefty amount for an XML file.  The save of all this new data took a little over a minute, but that is acceptable because we wouldnt typically be saving batches of 15k records, and the resulting XML file size is a little over a megabyte.  Not huge, but big enough to see some read performance numbers or so I thought.  It reads this file and renders the first team in under a second.  That is unbelievable, but we are lazy loading and the file really wasnt that big.  I will increase it to 50 teams with 100 players and 20 seasons each - 100,000 rows.  It took a year and a half to save all of that data, and resulted in an 8 megabyte file.  Seriously, if you are loading XML files this large, get a freaking database!  Despite this, it STILL takes under a second to load and render the first team, which is interesting mostly because I thought that it was loading that entire 8 MB XML file behind the scenes.  I have to say that I am quite impressed with the performance of the LINQ to XML approach, particularly since I took no efforts to optimize any of this code and was fairly new to the concept from the start.  There might be some merit to this little project after all Look out SQL Server and Oracle, use XML files instead!  Next up, I am going to completely pull the rug out from under the UI and change a number of entities in our model.  How well will the code be regenerated?  How much effort will be required to tie things back together in the UI?Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• TDD - beginner problems and stumbling blocks

  - by Noufal Ibrahim

  While I've written unit tests for most of the code I've done, I only recently got my hands on a copy of TDD by example by Kent Beck. I have always regretted certain design decisions I made since they prevented the application from being 'testable'. I read through the book and while some of it looks alien, I felt that I could manage it and decided to try it out on my current project which is basically a client/server system where the two pieces communicate via. USB. One on the gadget and the other on the host. The application is in Python. I started off and very soon got entangled in a mess of rewrites and tiny tests which I later figured didn't really test anything. I threw away most of them and and now have a working application for which the tests have all coagulated into just 2. Based on my experiences, I have a few questions which I'd like to ask. I gained some information from http://stackoverflow.com/questions/1146218/new-to-tdd-are-there-sample-applications-with-tests-to-show-how-to-do-tdd but have some specific questions which I'd like answers to/discussion on. Kent Beck uses a list which he adds to and strikes out from to guide the development process. How do you make such a list? I initially had a few items like "server should start up", "server should abort if channel is not available" etc. but they got mixed and finally now, it's just something like "client should be able to connect to server" (which subsumed server startup etc.). How do you handle rewrites? I initially selected a half duplex system based on named pipes so that I could develop the application logic on my own machine and then later add the USB communication part. It them moved to become a socket based thing and then moved from using raw sockets to using the Python SocketServer module. Each time things changed, I found that I had to rewrite considerable parts of the tests which was annoying. I'd figured that the tests would be a somewhat invariable guide during my development. They just felt like more code to handle. I needed a client and a server to communicate through the channel to test either side. I could mock one of the sides to test the other but then the whole channel wouldn't be tested and I worry that I'd miss that. This detracted from the whole red/green/refactor rhythm. Is this just lack of experience or am I doing something wrong? The "Fake it till you make it" left me with a lot of messy code that I later spent a lot of time to refactor and clean up. Is this the way things work? At the end of the session, I now have my client and server running with around 3 or 4 unit tests. It took me around a week to do it. I think I could have done it in a day if I were using the unit tests after code way. I fail to see the gain. I'm looking for comments and advice from people who have implemented large non trivial projects completely (or almost completely) using this methodology. It makes sense to me to follow the way after I have something already running and want to add a new feature but doing it from scratch seems to tiresome and not worth the effort. P.S. : Please let me know if this should be community wiki and I'll mark it like that. Update 0 : All the answers were equally helpful. I picked the one I did because it resonated with my experiences the most. Update 1: Practice Practice Practice!

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• What are the most common stumbling blocks when it comes to learning programming, in order of difficulty?

  - by blueberryfields

  I seem to remember that linked lists, recursion, pointers, and memory management are all good examples of stumbling blocks - places where the aspiring programmer typically ends up spending significant time trying to understand a concept before moving on and improving, and many end up giving up and not improving. I'm looking for a complete/comprehensive list of these types of stumbling blocks, in rough estimated order of difficulty to learn, with the goal of making sure that an educational program for programmers is structured to properly guide students through them Is this information available somewhere? Ideally, the difficulty to learn will be measured in some sort of objective manner (ie, % of students which consistently fail to learn the concept) What sources are most appropriate for obtaining this information?

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• How to see list of html-tidy errors in VIM for Windows?

  - by stumbling

  I am using Vim 7.2 on WinXP. I've tired to run tidy like this: :compiler tidy :make :copen When I do :copen it shows me no errors to jump to. I've seen references that shellpipe might need to be set a specific way, but that refers to an earlier version of VIM. How should I be using HTML-tidy with VIM, and do I need to mess with shellpipe to get it to work with WinXP?

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• How to Identify and Avoid Search Engine Blocks

  Search engines can sometimes take the best designed sites and can completely ignore a lot of modern elements of a webpage. A search engine spider will come across a number of stumbling blocks that are in many ways not in agreement with what they are looking for even if the content is embedded in the so called blocks.

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• Are there any web-sites out there that block IE altogether?

  - by Šime Vidas

  Since IE8 is such a backward browser, I was wondering if there are any web-sites on the Internet that just don't support IE altogether (and block it via conditional comments, for instance)? I remember stumbling upon web-sites that block Firefox in the past (like ~2004). The justification of blocking IE is (obviously): You don't want to deal with IE bugs, and you don't want to have to maintain IE-specific hack and workarounds.

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• Can I extract a specific folder using tar to another folder?

  - by PeanutsMonkey

  I am new to the world of Linux and seem to have run into a stumbling block. I know I can extract a specifc archive using the command tar xvfz archivename.tar.gz sampledir/ however how can I extract sampledir/ to testdir/ rather than the path that the archive is in e.g.currently the archive is in the path /tmp/archivename.tar.gz and I would like to extract sampledir to testdir which is in the path /tmp/testdir.

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• How do I add a version number field to an office 2007 docx document?

  - by Jon Cage

  I've been having a crack at using fields in Word 2007 and have hit a slight stumbling block. I want to add a field which I can use in several parts of the document to represent the current version (something of the form v0.1 but I can't see an obvious way to do it). The only provision I've found for this is something called RevNum but that gets updated every time I save the document. Is there a field I've missed or a way of adding custom fields or something?

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• Is there a way to enable Windows CUA keys in Ubuntu?

  - by Alexey Romanov

  My years of habit in Windows have imprinted on me that Ctrl+X == Cut, Ctrl+C == Copy, and Ctrl+V == Paste everywhere (including Vim and Emacs). Now I've started using Ubuntu at work, and this has been the single biggest stumbling block so far. Can I somehow enable these shortcuts for all Ubuntu programs?

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• Find out how many memory my server would need ideally?

  - by Daniel

  I have a pretty busy GNU/Linux server that I think needs more RAM. I know that the free command doesn't show the amount of RAM that is used. So I was stumbling upon Commited_As in /proc/meminfo. It currently shows 57972 kB which isn't much. Is this the amount of RAM that the processes use "right now" or is this an estimate of how many additional RAM it would take to never run out of memory with this load?

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• Apache mod_proxy dynamic filter

  - by jrhicks

  How can I configure Apache to ProxyBlock content based on something dynamic such as time-of-day or max-use. Basicly I'm curious about the scriptability of Apache. My web-stumbling leads me to believe I can combine mod-proxy and mod-perl in interesting ways to do dynamic filtering. But I'm pretty lost. What are some general instructions, tutorials, books, technologies to begin scripting Apache (or any suitable proxy).

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• Program that groups windows into tabs

  - by Arithmomaniac

  I recall once stumbling on a program that could take multiple application windows and wrap them inside a large window with a tabbed interface. One use of this, for example, would be to wrap multiple instances of Excel into one window, and thus icon on the taskbar. I couldn't find mention of this program via Google, because of the multiple meanings of the word "window". Does anyone remember, or know of, such a program?

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• Any career related single one-stop forum hub..

  - by learnerforever

  Hi, Stumbling into SO and then its sibling sites like programmers.stackexchange,superuser has been tremendously useful to me and is a single stop for my technical problems,long unanswered curiosities and it has been very useful to get perspective from mature professionals. I am an IT professional.I am looking for a similar one-stop career related forum, where I can understand job descriptions of different professions, career growth path, what a day looks like, salary,strengths needed with people having been there. I am confused about my career and particularly of interest are things like professors in academia,researchers in R&D lab, software developers,architectures,testers,business analyst,it analyst and related. Thanks,

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• How to update a game off a database

  - by James Clifton

  I am currently writing a sports strategy management game (cricket) in PHP, with a MYSQL database, and I have come across one stumbling block - how do I update games where neither player is online? Cricket is a game played between two players, and when they (or one of them) is online then everything is fine; but what if neither player is online? This occurs when championship games are played, and these games need to happen at certain times for game reasons. At the moment I have a private web page that updates every 5 seconds, and each time it loads all games are updated; but then I have the problem that when my private web page stops (for example my computer crashes or my web browser plays up) the game stops updating! Any suggestions?

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• BREAKING NEWS: Bunny Inc. becomes a Social Enterprise

  - by kellsey.ruppel(at)oracle.com

  Bunny what? Is your business adaptive, agile, innovative, productive… profitable? No? Wondering how to make it so?Social Enterprise is gaining ground as a global trend to accelerate business performance by better engaging employees, partners and customers.Starting with this post we are looking forward to stimulate an open conversation on the benefits, the stumbling blocks and the best practices of the Enterprise 2.0 journey… but with a bunny smile!Is Social Enterprise revolutionary or evolutionary? How does it impact traditional systems (such as ERP, CRM, BPM, Portals)? How do you measure it? How do you avoid major mistakes?We want to share our vision and to hear from you. Tell us what you did, what you are going to do and what you would never do with social and ... start looking for the invasion of the #e20bunnies at #webcenterJoin the discussion on LinkedIn! And follow the conversation on Twitter!

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• BREAKING NEWS: Bunny Inc. becomes a Social Enterprise

  - by kellsey.ruppel(at)oracle.com

  Bunny what? Is your business adaptive, agile, innovative, productive… profitable? No? Wondering how to make it so?Social Enterprise is gaining ground as a global trend to accelerate business performance by better engaging employees, partners and customers.Starting with this post we are looking forward to stimulate an open conversation on the benefits, the stumbling blocks and the best practices of the Enterprise 2.0 journey… but with a bunny smile!Is Social Enterprise revolutionary or evolutionary? How does it impact traditional systems (such as ERP, CRM, BPM, Portals)? How do you measure it? How do you avoid major mistakes?We want to share our vision and to hear from you. Tell us what you did, what you are going to do and what you would never do with social and ... start looking for the invasion of the #e20bunnies at #webcenterJoin the discussion on LinkedIn! And follow the conversation on Twitter!Technorati Tags: UXP, collaboration, enterprise 2.0, modern user experience, oracle, portals, webcenter, e20bunnies

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• BREAKING NEWS: Bunny Inc. becomes a Social Enterprise

  - by kellsey.ruppel(at)oracle.com

  Bunny what? Is your business adaptive, agile, innovative, productive… profitable? No? Wondering how to make it so?Social Enterprise is gaining ground as a global trend to accelerate business performance by better engaging employees, partners and customers.Starting with this post we are looking forward to stimulate an open conversation on the benefits, the stumbling blocks and the best practices of the Enterprise 2.0 journey… but with a bunny smile!Is Social Enterprise revolutionary or evolutionary? How does it impact traditional systems (such as ERP, CRM, BPM, Portals)? How do you measure it? How do you avoid major mistakes?We want to share our vision and to hear from you. Tell us what you did, what you are going to do and what you would never do with social and ... start looking for the invasion of the #e20bunnies at #webcenterJoin the discussion on LinkedIn! And follow the conversation on Twitter!

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• How did craigspro license Craigslist content? [closed]

  - by Joshua Frank

  There's an app called craigspro that provides a much better interface to Craigslist on mobile devices. They claim that the app is Officially Licensed by Craigslist, but I thought Craigslist never licensed their content, and the only thing I can find on the subject in the terms of use is this: Any copying, aggregation, display, distribution, performance or derivative use of craigslist or any content posted on craigslist whether done directly or through intermediaries (including but not limited to by means of spiders, robots, crawlers, scrapers, framing, iframes or RSS feeds) is prohibited. As a limited exception, general purpose Internet search engines and noncommercial public archives will be entitled to access craigslist without individual written agreements executed with CL that specifically authorize an exception to this prohibition if ... Does anyone know how do get a "written agreement" with Craigslist, and roughly what their terms would be? Do they charge a fee, or just check that you're not evil? I'll try next with Craigslist directly, but I'd like to get a sense of the landscape before stumbling in.

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• Graphic demonstrating emphasis of front end in web apps

  - by sohail

  I remember stumbling across an amusing graphic a year or so ago which demonstrated the tiers of web development. The back-end was shown as a tiny box, but the front end was shown as a huge box crammed with lots of front-end technologies like AJAX, DHTML. This is all a vague recollection. Does anyone know where on the Intraweb this graphic might be? It was probably on a programming cartoon site, but I only view XKCD on a regular basis, and I couldn't find it on there. Although tagged as fun, my request does have a productive edge to it - it would be quite useful in driving home to my colleagues how UI top-heavy web application development has become.

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