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  • Top 10 Reasons SQL Developer is Perfect for Oracle Beginners

    - by thatjeffsmith
    Learning new technologies can be daunting. If you’ve never used a Mac before, you’ll probably be a bit baffled at first. But, you’re probably at least coming from a desktop computing background (Windows), so you common frame of reference. But what if you’re just now learning to use a relational database? Yes, you’ve played with Access a bit, but now your employer or college instructor has charged you with becoming proficient with Oracle database. Here’s 10 reasons why I think Oracle SQL Developer is the perfect vehicle to help get you started. 1. It’s free No need to break into one of these… No start-up costs, no need to wrangle budget dollars from your company. Students don’t have any money after books and lab fees anyway. And most employees don’t like having to ask for ‘special’ software anyway. So avoid all of that and make sure the free stuff doesn’t suit your needs first. Upgrades are available on a regular base, also at no cost, and support is freely available via our public forums. 2. It will run pretty much anywhere Windows – check. OSX (Apple) – check. Unix – check. Linux – check. No need to start up a windows VM to run your Windows-only software in your lab machine. 3. Anyone can install it There’s no installer, no registry to be updated, no admin privs to be obtained. If you can download and extract files to your machine or USB storage device, you can run it. You can be up and running with SQL Developer in under 5 minutes. Here’s a video tutorial to see how to get started. 4. It’s ubiquitous I admit it, I learned a new word yesterday and I wanted an excuse to use it. SQL Developer’s everywhere. It’s had over 2,500,000 downloads in the past year, and is the one of the most downloaded items from OTN. This means if you need help, there’s someone sitting nearby you that can assist, and since they’re in the same tool as you, they’ll be speaking the same language. 5. Simple User Interface Up-up-down-down-Left-right-left-right-A-B-A-B-START will get you 30 lives, but you already knew that, right? You connect, you see your objects, you click on your objects. Or, you can use the worksheet to write your queries and programs in. There’s only one toolbar, and just a few buttons. If you’re like me, video games became less fun when each button had 6 action items mapped to it. I just want the good ole ‘A’, ‘B’, ‘SELECT’, and ‘START’ controls. If you’re new to Oracle, you shouldn’t have the double-workload of learning a new complicated tool as well. 6. It’s not a ‘black box’ Click through your objects, but also get the SQL that drives the GUI As you use the wizards to accomplish tasks for you, you can view the SQL statement being generated on your behalf. Just because you have a GUI, doesn’t mean you’re ceding your responsibility to learn the underlying code that makes the database work. 7. It’s four tools in one It’s not just a query tool. Maybe you need to design a data model first? Or maybe you need to migrate your Sybase ASE database to Oracle for a new project? Or maybe you need to create some reports? SQL Developer does all of that. So once you get comfortable with one part of the tool, the others will be much easier to pick up as your needs change. 8. Great learning resources available Videos, blogs, hands-on learning labs – you name it, we got it. Why wait for someone to train you, when you can train yourself at your own pace? 9. You can use it to teach yourself SQL Instead of being faced with the white-screen-of-panic, you can visually build your queries by dragging and dropping tables and views into the Query Builder. Yes, ‘just like Access’ – only better. And as you build your query, toggle to the Worksheet panel and see the SQL statement. Again, SQL Developer is not a black box. If you prefer to learn by trial and error, the worksheet will attempt to suggest the next bit of your SQL statement with it’s completion insight feature. And if you have syntax errors, those will be highlighted – just like your misspelled words in your favorite word processor. 10. It scales to match your experience level You won’t be a n00b forever. In 6-8 months, when you’re ready to tackle something a bit more complicated, like XML DB or Oracle Spatial, the tool is already there waiting on you. No need to go out and find the ‘advanced’ tool. 11. Wait, you said this was a ‘Top 10′ list? Yes. Yes, I did. I’m using this ‘trick’ to get you to continue reading because I’m going to say something you might not want to hear. Are you ready? Tools won’t replace experience, failure, hard work, and training. Just because you have the keys to the car, doesn’t mean you’re ready to head out on the race track. While SQL Developer reduces the barriers to entry, it does not completely remove them. Many experienced folks simply do not like tools. Rather, they don’t like the people that pick up tools without the know-how to properly use them. If you don’t understand what ‘TRUNCATE’ means, don’t try it out. Try picking up a book first. Of course, it’s very nice to have your own sandbox to play in, so you don’t upset the other children. That’s why I really like our Dev Days Database Virtual Box image. It’s your own database to learn and experiment with.

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  • Bye Bye Year of the Dragon, Hello BPM

    - by Ajay Khanna
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} As 2012 fades and we usher in a New Year, let’s look back at some of the hottest BPM trends and those we’ll be seeing more of in the coming months. BPM is as much about people as it is about technology. As people adopt new ways of engagement, new channels of communications and new devices to interact , the changes are reflected in BPM practices. As Social and Mobile have become an integral part of our personal and professional lives, we’ll see tighter integration of social and mobile with BPM, and more use cases emerging for smarter process management in 2013. And with products and services becoming less differentiated, organizations will strive to differentiate on Customer Experience. Concepts like Pace Layered Architecture and Dynamic Case Management will provide more flexibility and agility to IT groups and knowledge workers. Take a look at some of these capabilities we showcased (see video) at Oracle OpenWorld 2012. Some of these trends that will continue to gain momentum in 2013: Social networks and social media have provided a new way for businesses to engage with customers. A prospect is likely to reach out to their social network before making any purchase. Companies are increasingly engaging with customers in social networks to influence their purchasing decisions, as well as listening to customers via tools like sentiment analysis to see what customers think about a particular product or process. These insights are valuable as companies look to improve their processes. Inside organizations, workers are using social tools to engage with each other to design new products and processes. Social collaboration tools are being used to resolve issues where an employee needs consultation to reach a decision. Oracle BPM Suite includes social interaction as an integral part of its process design and work management to empower today’s business users. Ubiquitous smart mobile devices are trending as a tool of choice for many workers. Many companies are adopting the policy of “Bring Your Own Device,” and the device of choice is a tablet. Devices like smart phones and tablets not only provide mobility to workers and customers, but they also provide additional important information – the context. By integrating the mobile context (location, photos, and preferences) into your processes, organizations can make much more informed decisions, as well as offer more personalized service to customers. Using Oracle ADF Mobile, you can easily create user interfaces for mobile devices and also capture location data for process execution. Customer experience was at the forefront of trending topics in 2012. Organizations are trying to understand their customers better and offer them more personalized and differentiated services. Customer experience is paramount when companies design sales and support processes. Companies are looking to BPM to consistently and efficiently orchestrate customer facing processes across disparate systems, departments and channels of communication. Oracle BPM Suite provides just the right capabilities for organizations to design and deliver an excellent customer experience. Pace Layered Architecture strategy is gaining traction as a way to maximize agility and minimize disruption in organizations. It provides a framework to manage the evolution of your information system when different pieces of it are changing at different rates and need to be updated independent of one another. Oracle Fusion Middleware and Oracle BPM Suite are designed with this in mind. The database layer, integration layer, application layer, and process layer should not be required to change at the same time. Most of the business changes to policy or process can be done at the process layer without disrupting the whole infrastructure. By understanding the type of change needed at a particular level, organizations can become much more agile and efficient. Adaptive Case Management proposes more flexibility to manage processes or cases that do not follow a structured process flow. In such situations, the knowledge worker managing the case needs to evaluate what step should occur next because the sequence of steps can’t be predetermined. Another characteristic is that it requires much more collaboration than straight-through process. As simple processes become automated, and customers adopt more and more self-service, cases that reach the case workers are much more complex and need more investigation. Oracle BPM suite includes comprehensive adaptive case management capability to manage such unstructured and complex processes. Smart BPM or making your BPM intelligent has been the holy grail for BPM practitioners who imagined that one day BPM would become one with Business Intelligence, Business Activity Monitoring and Complex Event Processing, making it much more responsive and helpful in organizational decision making. In 2013, organizations will begin to deploy these intelligent BPM solutions. Oracle offers an integrated solution that brings together the powerful functionality of BI, BAM, event processing, and Real Time Decisions to help organizations create smart process based solutions. In order to help customers reach their BPM goals faster and remove risks associated with BPM initiatives, Oracle has introduced Oracle Process Accelerators, pre-built best practices applications built on Oracle BPM Suite that are fully production grade and ready to deploy. These are exiting times for BPM practitioners and there is so much to look forward to in 2013. We wish you a very happy and prosperous New Year 2013. Happy BPMing!

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  • Using a "white list" for extracting terms for Text Mining

    - by [email protected]
    In Part 1 of my post on "Generating cluster names from a document clustering model" (part 1, part 2, part 3), I showed how to build a clustering model from text documents using Oracle Data Miner, which automates preparing data for text mining. In this process we specified a custom stoplist and lexer and relied on Oracle Text to identify important terms.  However, there is an alternative approach, the white list, which uses a thesaurus object with the Oracle Text CTXRULE index to allow you to specify the important terms. INTRODUCTIONA stoplist is used to exclude, i.e., black list, specific words in your documents from being indexed. For example, words like a, if, and, or, and but normally add no value when text mining. Other words can also be excluded if they do not help to differentiate documents, e.g., the word Oracle is ubiquitous in the Oracle product literature. One problem with stoplists is determining which words to specify. This usually requires inspecting the terms that are extracted, manually identifying which ones you don't want, and then re-indexing the documents to determine if you missed any. Since a corpus of documents could contain thousands of words, this could be a tedious exercise. Moreover, since every word is considered as an individual token, a term excluded in one context may be needed to help identify a term in another context. For example, in our Oracle product literature example, the words "Oracle Data Mining" taken individually are not particular helpful. The term "Oracle" may be found in nearly all documents, as with the term "Data." The term "Mining" is more unique, but could also refer to the Mining industry. If we exclude "Oracle" and "Data" by specifying them in the stoplist, we lose valuable information. But it we include them, they may introduce too much noise. Still, when you have a broad vocabulary or don't have a list of specific terms of interest, you rely on the text engine to identify important terms, often by computing the term frequency - inverse document frequency metric. (This is effectively a weight associated with each term indicating its relative importance in a document within a collection of documents. We'll revisit this later.) The results using this technique is often quite valuable. As noted above, an alternative to the subtractive nature of the stoplist is to specify a white list, or a list of terms--perhaps multi-word--that we want to extract and use for data mining. The obvious downside to this approach is the need to specify the set of terms of interest. However, this may not be as daunting a task as it seems. For example, in a given domain (Oracle product literature), there is often a recognized glossary, or a list of keywords and phrases (Oracle product names, industry names, product categories, etc.). Being able to identify multi-word terms, e.g., "Oracle Data Mining" or "Customer Relationship Management" as a single token can greatly increase the quality of the data mining results. The remainder of this post and subsequent posts will focus on how to produce a dataset that contains white list terms, suitable for mining. CREATING A WHITE LIST We'll leverage the thesaurus capability of Oracle Text. Using a thesaurus, we create a set of rules that are in effect our mapping from single and multi-word terms to the tokens used to represent those terms. For example, "Oracle Data Mining" becomes "ORACLEDATAMINING." First, we'll create and populate a mapping table called my_term_token_map. All text has been converted to upper case and values in the TERM column are intended to be mapped to the token in the TOKEN column. TERM                                TOKEN DATA MINING                         DATAMINING ORACLE DATA MINING                  ORACLEDATAMINING 11G                                 ORACLE11G JAVA                                JAVA CRM                                 CRM CUSTOMER RELATIONSHIP MANAGEMENT    CRM ... Next, we'll create a thesaurus object my_thesaurus and a rules table my_thesaurus_rules: CTX_THES.CREATE_THESAURUS('my_thesaurus', FALSE); CREATE TABLE my_thesaurus_rules (main_term     VARCHAR2(100),                                  query_string  VARCHAR2(400)); We next populate the thesaurus object and rules table using the term token map. A cursor is defined over my_term_token_map. As we iterate over  the rows, we insert a synonym relationship 'SYN' into the thesaurus. We also insert into the table my_thesaurus_rules the main term, and the corresponding query string, which specifies synonyms for the token in the thesaurus. DECLARE   cursor c2 is     select token, term     from my_term_token_map; BEGIN   for r_c2 in c2 loop     CTX_THES.CREATE_RELATION('my_thesaurus',r_c2.token,'SYN',r_c2.term);     EXECUTE IMMEDIATE 'insert into my_thesaurus_rules values                        (:1,''SYN(' || r_c2.token || ', my_thesaurus)'')'     using r_c2.token;   end loop; END; We are effectively inserting the token to return and the corresponding query that will look up synonyms in our thesaurus into the my_thesaurus_rules table, for example:     'ORACLEDATAMINING'        SYN ('ORACLEDATAMINING', my_thesaurus)At this point, we create a CTXRULE index on the my_thesaurus_rules table: create index my_thesaurus_rules_idx on        my_thesaurus_rules(query_string)        indextype is ctxsys.ctxrule; In my next post, this index will be used to extract the tokens that match each of the rules specified. We'll then compute the tf-idf weights for each of the terms and create a nested table suitable for mining.

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  • Refactoring Part 1 : Intuitive Investments

    - by Wes McClure
    Fear, it’s what turns maintaining applications into a nightmare.  Technology moves on, teams move on, someone is left to operate the application, what was green is now perceived brown.  Eventually the business will evolve and changes will need to be made.  The approach to those changes often dictates the long term viability of the application.  Fear of change, lack of passion and a lack of interest in understanding the domain often leads to a paranoia to do anything that doesn’t involve duct tape and bailing twine.  Don’t get me wrong, those have a place in the short term viability of a project but they don’t have a place in the long term.  Add to it “us versus them” in regards to the original team and those that maintain it, internal politics and other factors and you have a recipe for disaster.  This results in code that quickly becomes unmanageable.  Even the most clever of designs will eventually become sub optimal and debt will amount that exponentially makes changes difficult.  This is where refactoring comes in, and it’s something I’m very passionate about.  Refactoring is about improving the process whereby we make change, it’s an exponential investment in the process of change. Without it we will incur exponential complexity that halts productivity. Investments, especially in the long term, require intuition and reflection.  How can we tackle new development effectively via evolving the original design and paying off debt that has been incurred? The longer we wait to ask and answer this question, the more it will cost us.  Small requests don’t warrant big changes, but realizing when changes now will pay off in the long term, and especially in the short term, is valuable. I have done my fair share of maintaining applications and continuously refactoring as needed, but recently I’ve begun work on a project that hasn’t had much debt, if any, paid down in years.  This is the first in a series of blog posts to try to capture the process which is largely driven by intuition of smaller refactorings from other projects. Signs that refactoring could help: Testability How can decreasing test time not pay dividends? One of the first things I found was that a very important piece often takes 30+ minutes to test.  I can only imagine how much time this has cost historically, but more importantly the time it might cost in the coming weeks: I estimate at least 10-20 hours per person!  This is simply unacceptable for almost any situation.  As it turns out, about 6 hours of working with this part of the application and I was able to cut the time down to under 30 seconds!  In less than the lost time of one week, I was able to fix the problem for all future weeks! If we can’t test fast then we can’t change fast, nor with confidence. Code is used by end users and it’s also used by developers, consider your own needs in terms of the code base.  Adding logic to enable/disable features during testing can help decouple parts of an application and lead to massive improvements.  What exactly is so wrong about test code in real code?  Often, these become features for operators and sometimes end users.  If you cannot run an integration test within a test runner in your IDE, it’s time to refactor. Readability Are variables named meaningfully via a ubiquitous language? Is the code segmented functionally or behaviorally so as to minimize the complexity of any one area? Are aspects properly segmented to avoid confusion (security, logging, transactions, translations, dependency management etc) Is the code declarative (what) or imperative (how)?  What matters, not how.  LINQ is a great abstraction of the what, not how, of collection manipulation.  The Reactive framework is a great example of the what, not how, of managing streams of data. Are constants abstracted and named, or are they just inline? Do people constantly bitch about the code/design? If the code is hard to understand, it will be hard to change with confidence.  It’s a large undertaking if the original designers didn’t pay much attention to readability and as such will never be done to “completion.”  Make sure not to go over board, instead use this as you change an application, not in lieu of changes (like with testability). Complexity Simplicity will never be achieved, it’s highly subjective.  That said, a lot of code can be significantly simplified, tidy it up as you go.  Refactoring will often converge upon a simplification step after enough time, keep an eye out for this. Understandability In the process of changing code, one often gains a better understanding of it.  Refactoring code is a good way to learn how it works.  However, it’s usually best in combination with other reasons, in effect killing two birds with one stone.  Often this is done when readability is poor, in which case understandability is usually poor as well.  In the large undertaking we are making with this legacy application, we will be replacing it.  Therefore, understanding all of its features is important and this refactoring technique will come in very handy. Unused code How can deleting things not help? This is a freebie in refactoring, it’s very easy to detect with modern tools, especially in statically typed languages.  We have VCS for a reason, if in doubt, delete it out (ok that was cheesy)! If you don’t know where to start when refactoring, this is an excellent starting point! Duplication Do not pray and sacrifice to the anti-duplication gods, there are excellent examples where consolidated code is a horrible idea, usually with divergent domains.  That said, mediocre developers live by copy/paste.  Other times features converge and aren’t combined.  Tools for finding similar code are great in the example of copy/paste problems.  Knowledge of the domain helps identify convergent concepts that often lead to convergent solutions and will give intuition for where to look for conceptual repetition. 80/20 and the Boy Scouts It’s often said that 80% of the time 20% of the application is used most.  These tend to be the parts that are changed.  There are also parts of the code where 80% of the time is spent changing 20% (probably for all the refactoring smells above).  I focus on these areas any time I make a change and follow the philosophy of the Boy Scout in cleaning up more than I messed up.  If I spend 2 hours changing an application, in the 20%, I’ll always spend at least 15 minutes cleaning it or nearby areas. This gives a huge productivity edge on developers that don’t. Ironically after a short period of time the 20% shrinks enough that we don’t have to spend 80% of our time there and can move on to other areas.   Refactoring is highly subjective, never attempt to refactor to completion!  Learn to be comfortable with leaving one part of the application in a better state than others.  It’s an evolution, not a revolution.  These are some simple areas to look into when making changes and can help get one started in the process.  I’ve often found that refactoring is a convergent process towards simplicity that sometimes spans a few hours but often can lead to massive simplifications over the timespan of weeks and months of regular development.

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  • Using LINQ Distinct: With an Example on ASP.NET MVC SelectListItem

    - by Joe Mayo
    One of the things that might be surprising in the LINQ Distinct standard query operator is that it doesn’t automatically work properly on custom classes. There are reasons for this, which I’ll explain shortly. The example I’ll use in this post focuses on pulling a unique list of names to load into a drop-down list. I’ll explain the sample application, show you typical first shot at Distinct, explain why it won’t work as you expect, and then demonstrate a solution to make Distinct work with any custom class. The technologies I’m using are  LINQ to Twitter, LINQ to Objects, Telerik Extensions for ASP.NET MVC, ASP.NET MVC 2, and Visual Studio 2010. The function of the example program is to show a list of people that I follow.  In Twitter API vernacular, these people are called “Friends”; though I’ve never met most of them in real life. This is part of the ubiquitous language of social networking, and Twitter in particular, so you’ll see my objects named accordingly. Where Distinct comes into play is because I want to have a drop-down list with the names of the friends appearing in the list. Some friends are quite verbose, which means I can’t just extract names from each tweet and populate the drop-down; otherwise, I would end up with many duplicate names. Therefore, Distinct is the appropriate operator to eliminate the extra entries from my friends who tend to be enthusiastic tweeters. The sample doesn’t do anything with the drop-down list and I leave that up to imagination for what it’s practical purpose could be; perhaps a filter for the list if I only want to see a certain person’s tweets or maybe a quick list that I plan to combine with a TextBox and Button to reply to a friend. When the program runs, you’ll need to authenticate with Twitter, because I’m using OAuth (DotNetOpenAuth), for authentication, and then you’ll see the drop-down list of names above the grid with the most recent tweets from friends. Here’s what the application looks like when it runs: As you can see, there is a drop-down list above the grid. The drop-down list is where most of the focus of this article will be. There is some description of the code before we talk about the Distinct operator, but we’ll get there soon. This is an ASP.NET MVC2 application, written with VS 2010. Here’s the View that produces this screen: <%@ Page Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<TwitterFriendsViewModel>" %> <%@ Import Namespace="DistinctSelectList.Models" %> <asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server">     Home Page </asp:Content><asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">     <fieldset>         <legend>Twitter Friends</legend>         <div>             <%= Html.DropDownListFor(                     twendVM => twendVM.FriendNames,                     Model.FriendNames,                     "<All Friends>") %>         </div>         <div>             <% Html.Telerik().Grid<TweetViewModel>(Model.Tweets)                    .Name("TwitterFriendsGrid")                    .Columns(cols =>                     {                         cols.Template(col =>                             { %>                                 <img src="<%= col.ImageUrl %>"                                      alt="<%= col.ScreenName %>" />                         <% });                         cols.Bound(col => col.ScreenName);                         cols.Bound(col => col.Tweet);                     })                    .Render(); %>         </div>     </fieldset> </asp:Content> As shown above, the Grid is from Telerik’s Extensions for ASP.NET MVC. The first column is a template that renders the user’s Avatar from a URL provided by the Twitter query. Both the Grid and DropDownListFor display properties that are collections from a TwitterFriendsViewModel class, shown below: using System.Collections.Generic; using System.Web.Mvc; namespace DistinctSelectList.Models { /// /// For finding friend info on screen /// public class TwitterFriendsViewModel { /// /// Display names of friends in drop-down list /// public List FriendNames { get; set; } /// /// Display tweets in grid /// public List Tweets { get; set; } } } I created the TwitterFreindsViewModel. The two Lists are what the View consumes to populate the DropDownListFor and Grid. Notice that FriendNames is a List of SelectListItem, which is an MVC class. Another custom class I created is the TweetViewModel (the type of the Tweets List), shown below: namespace DistinctSelectList.Models { /// /// Info on friend tweets /// public class TweetViewModel { /// /// User's avatar /// public string ImageUrl { get; set; } /// /// User's Twitter name /// public string ScreenName { get; set; } /// /// Text containing user's tweet /// public string Tweet { get; set; } } } The initial Twitter query returns much more information than we need for our purposes and this a special class for displaying info in the View.  Now you know about the View and how it’s constructed. Let’s look at the controller next. The controller for this demo performs authentication, data retrieval, data manipulation, and view selection. I’ll skip the description of the authentication because it’s a normal part of using OAuth with LINQ to Twitter. Instead, we’ll drill down and focus on the Distinct operator. However, I’ll show you the entire controller, below,  so that you can see how it all fits together: using System.Linq; using System.Web.Mvc; using DistinctSelectList.Models; using LinqToTwitter; namespace DistinctSelectList.Controllers { [HandleError] public class HomeController : Controller { private MvcOAuthAuthorization auth; private TwitterContext twitterCtx; /// /// Display a list of friends current tweets /// /// public ActionResult Index() { auth = new MvcOAuthAuthorization(InMemoryTokenManager.Instance, InMemoryTokenManager.AccessToken); string accessToken = auth.CompleteAuthorize(); if (accessToken != null) { InMemoryTokenManager.AccessToken = accessToken; } if (auth.CachedCredentialsAvailable) { auth.SignOn(); } else { return auth.BeginAuthorize(); } twitterCtx = new TwitterContext(auth); var friendTweets = (from tweet in twitterCtx.Status where tweet.Type == StatusType.Friends select new TweetViewModel { ImageUrl = tweet.User.ProfileImageUrl, ScreenName = tweet.User.Identifier.ScreenName, Tweet = tweet.Text }) .ToList(); var friendNames = (from tweet in friendTweets select new SelectListItem { Text = tweet.ScreenName, Value = tweet.ScreenName }) .Distinct() .ToList(); var twendsVM = new TwitterFriendsViewModel { Tweets = friendTweets, FriendNames = friendNames }; return View(twendsVM); } public ActionResult About() { return View(); } } } The important part of the listing above are the LINQ to Twitter queries for friendTweets and friendNames. Both of these results are used in the subsequent population of the twendsVM instance that is passed to the view. Let’s dissect these two statements for clarification and focus on what is happening with Distinct. The query for friendTweets gets a list of the 20 most recent tweets (as specified by the Twitter API for friend queries) and performs a projection into the custom TweetViewModel class, repeated below for your convenience: var friendTweets = (from tweet in twitterCtx.Status where tweet.Type == StatusType.Friends select new TweetViewModel { ImageUrl = tweet.User.ProfileImageUrl, ScreenName = tweet.User.Identifier.ScreenName, Tweet = tweet.Text }) .ToList(); The LINQ to Twitter query above simplifies what we need to work with in the View and the reduces the amount of information we have to look at in subsequent queries. Given the friendTweets above, the next query performs another projection into an MVC SelectListItem, which is required for binding to the DropDownList.  This brings us to the focus of this blog post, writing a correct query that uses the Distinct operator. The query below uses LINQ to Objects, querying the friendTweets collection to get friendNames: var friendNames = (from tweet in friendTweets select new SelectListItem { Text = tweet.ScreenName, Value = tweet.ScreenName }) .Distinct() .ToList(); The above implementation of Distinct seems normal, but it is deceptively incorrect. After running the query above, by executing the application, you’ll notice that the drop-down list contains many duplicates.  This will send you back to the code scratching your head, but there’s a reason why this happens. To understand the problem, we must examine how Distinct works in LINQ to Objects. Distinct has two overloads: one without parameters, as shown above, and another that takes a parameter of type IEqualityComparer<T>.  In the case above, no parameters, Distinct will call EqualityComparer<T>.Default behind the scenes to make comparisons as it iterates through the list. You don’t have problems with the built-in types, such as string, int, DateTime, etc, because they all implement IEquatable<T>. However, many .NET Framework classes, such as SelectListItem, don’t implement IEquatable<T>. So, what happens is that EqualityComparer<T>.Default results in a call to Object.Equals, which performs reference equality on reference type objects.  You don’t have this problem with value types because the default implementation of Object.Equals is bitwise equality. However, most of your projections that use Distinct are on classes, just like the SelectListItem used in this demo application. So, the reason why Distinct didn’t produce the results we wanted was because we used a type that doesn’t define its own equality and Distinct used the default reference equality. This resulted in all objects being included in the results because they are all separate instances in memory with unique references. As you might have guessed, the solution to the problem is to use the second overload of Distinct that accepts an IEqualityComparer<T> instance. If you were projecting into your own custom type, you could make that type implement IEqualityComparer<T>, but SelectListItem belongs to the .NET Framework Class Library.  Therefore, the solution is to create a custom type to implement IEqualityComparer<T>, as in the SelectListItemComparer class, shown below: using System.Collections.Generic; using System.Web.Mvc; namespace DistinctSelectList.Models { public class SelectListItemComparer : EqualityComparer { public override bool Equals(SelectListItem x, SelectListItem y) { return x.Value.Equals(y.Value); } public override int GetHashCode(SelectListItem obj) { return obj.Value.GetHashCode(); } } } The SelectListItemComparer class above doesn’t implement IEqualityComparer<SelectListItem>, but rather derives from EqualityComparer<SelectListItem>. Microsoft recommends this approach for consistency with the behavior of generic collection classes. However, if your custom type already derives from a base class, go ahead and implement IEqualityComparer<T>, which will still work. EqualityComparer is an abstract class, that implements IEqualityComparer<T> with Equals and GetHashCode abstract methods. For the purposes of this application, the SelectListItem.Value property is sufficient to determine if two items are equal.   Since SelectListItem.Value is type string, the code delegates equality to the string class. The code also delegates the GetHashCode operation to the string class.You might have other criteria in your own object and would need to define what it means for your object to be equal. Now that we have an IEqualityComparer<SelectListItem>, let’s fix the problem. The code below modifies the query where we want distinct values: var friendNames = (from tweet in friendTweets select new SelectListItem { Text = tweet.ScreenName, Value = tweet.ScreenName }) .Distinct(new SelectListItemComparer()) .ToList(); Notice how the code above passes a new instance of SelectListItemComparer as the parameter to the Distinct operator. Now, when you run the application, the drop-down list will behave as you expect, showing only a unique set of names. In addition to Distinct, other LINQ Standard Query Operators have overloads that accept IEqualityComparer<T>’s, You can use the same techniques as shown here, with SelectListItemComparer, with those other operators as well. Now you know how to resolve problems with getting Distinct to work properly and also have a way to fix problems with other operators that require equality comparisons. @JoeMayo

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  • Oracle Fusion Applications: Changing the Game

    - by kellsey.ruppel(at)oracle.com
    Originally posted in the Oracle Profit Magazine, November 2010 Edition. When the order processing system red-flags a customer's credit status, the IT department doesn't get the customer's call. When a supplier misses a delivery date for a key automotive assembly, it's not the CIO who has to answer for the error. Knowledge workers (known in IT circles as "users") are on the front lines when an exception occurs in an established business process. They're also the ones who study sales trends to decide when to open a new store in an up-and-coming neighborhood, which products are most profitable, how employee skill sets are evolving, and which suppliers are most efficient. In short, knowledge workers are masters of business as unusual. Traditional enterprise resource planning (ERP) systems and other familiar enterprise applications excel at automating, managing, and executing standard business processes. These programs shine when everything goes as planned. Life gets even trickier when a traditional application needs to be extended with a new service or an extra step is added to a business process when new products are brought to market, divisions are merged, or companies are acquired. Monolithic applications often need the IT department to step in and make the necessary adjustments--incurring additional costs and delays. Until now. When Oracle unveiled the much-anticipated family of Oracle Fusion Applications at Oracle OpenWorld in September 2010, knowledge workers in particular had a lot to cheer about. Business users will soon have ready access to analytical information and collaboration tools in the context of what they are working on, so they can make better decisions when problems or opportunities arise. Additionally, the Oracle Fusion Applications platform will make it easy for business users to tweak processes, create new capabilities, and find information, often without the need for IT department assistance and while still following company guidelines. And IT leaders will be happy to hear about new deployment options, guided implementation and setup tools, and cost-saving management capabilities. Just as important, the underlying technologies in Oracle Fusion Applications will allow organizations to choose among their existing investments and next-generation enterprise applications so they can introduce innovations at a pace that makes the most business and financial sense. "Oracle Fusion Applications are architected so you don't have to do rip and replace," says Jim Hayes, managing director of the consulting firm Accenture. "That's very important for creating a business case that will get through the steering committee and be approved by the board. It shows you can drive value and make a difference in the near term." For these and other reasons, analysts and early adopters are calling Oracle Fusion Applications a game changer for enterprise customers. The differences become apparent in three key areas: the way we innovate, work, and adopt technology. Game Changer #1: New Standard for InnovationChange is a constant challenge for most businesses, whether the catalysts are market dynamics, new competition, or the ever-expanding regulatory environment. And, in an ongoing effort to differentiate, business leaders are constantly looking for new ways to do business, serve constituents, and bring new products and services to market. In addition, companies face significant costs to keep their applications up-to-date. For example, when a company adds new suppliers to a procurement system, the IT shop typically has to invest time, effort, and even consulting fees for custom integrations that allow various ERP systems to communicate with each other. Oracle Fusion Applications were built on Web services and a modular SOA foundation to ease customizations and integration activities among all applications--whether from Oracle or another vendor. Interfaces and updates written in ubiquitous Java, rather than a proprietary coding language, allow organizations to tap into existing in-house technical skills rather than seek expensive outside specialists. And with SOA, organizations can extend a feature set or integrate with other SOA environments by combining Web services such as "look up customer" into a new business process managed by the BPEL orchestration engine. Flexibility like this has long-term implications. "Because users capture these changes at a higher metadata layer, not in the application's code, changes and additions are protected even as new versions of Oracle Fusion Applications are released," says Steve Miranda, senior vice president of applications development at Oracle. "This is a much more sustainable approach because you don't incur costly customizations that prevent upgrades and other innovations." And changes are easier to make: if one change is made in the metadata, that change is automatically reflected throughout the application interface, business intelligence, business process, and business logic. Game Changer #2: New Standard for WorkBoosting productivity comes down to doing the basics right: running business processes more efficiently and managing exceptions more effectively, so users can accomplish more in the course of a day or spend more quality time with the most profitable customers. The fastest way to improve process efficiency is to reduce the number of steps it takes to execute common tasks, such as ordering office equipment from an internal procurement system. Oracle Fusion Applications will deliver a complete role-based user experience with business intelligence and collaboration capabilities provided in the context of the work at hand. "We created every Oracle Fusion Applications screen by asking 'What does the user need to know?' 'What does he or she need to do?' and 'Who do they need to work with to get the job done?'" Miranda explains. So when the sales department heads need new laptops, the self-service procurement screen will not only display a list of approved vendors and configurations, but also a running list of reviews by coworkers who recently purchased the various models. Embedded intelligence may also display prevailing delivery lead times based on actual order histories, not the generic shipping dates vendors may quote. The pervasive business intelligence serves many other business activities across all areas of the enterprise. For example, a manager considering whether to promote a direct report can see the person's employee profile, with a salary history, appraisal summaries, and a rundown of skills and training. This approach to business intelligence also has implications for supply chain management. "One of the challenges at Ingersoll Rand is lack of visibility in our supply chain," says Mike Macrie, global director of enterprise applications for global industrial firm Ingersoll Rand. "Oracle Fusion Applications are going to provide the embedded intelligence to give us that visibility and give us the ability to analyze those orders at any point in our supply chain." Oracle Fusion Applications will also create a "role-based user experience" that displays a work list of events that need attention, based on user job function. Role awareness guides users with daily lists of action items and exceptions. So a credit manager may see seven invoices with discounts that are about to expire or 12 suppliers that have been put on hold because credit memos are awaiting approval. Individualization extends to the search capabilities of Oracle Fusion Applications. The platform uses Web-style search screens powered by an Oracle enterprise search engine, with a security framework that filters search results so individuals will only see the internal information they're authorized to access. A further aid to productivity is Oracle Fusion Applications' integration with Web 2.0 collaboration and social networking resources for business environments. Hover-over text will reveal relevant contact information whenever the name of a person appears in an Oracle Fusion Application. Users can connect via an online chat, phone call, or instant message without leaving the main application, reducing the time required for an accounts payable staffer to resolve a mismatch between an invoiced charge and the service record, for example. Addresses of suppliers, customers, or partners will also initiate hover-over text to show contact details and Web-based maps. Finally, Oracle Fusion Applications will promote a new way of working with purpose-driven communities that can bring new efficiencies to everything from cultivating sales leads to managing new projects. As soon as a lead or project materializes, the applications will automatically gather relevant participants into an online community that shares member contact information, schedules, discussion forums, and Wiki pages. "Oracle Fusion Applications will allow us to take it to the next level with embedded Web 2.0 tools and the embedded analytics," says Steve Printz, CIO and vice president, supply chain management, at window-and-door manufacturer Pella. "[This] allows those employees today who are processing transactions to really contribute to the success of the company and become decision-makers." Game Changer #3: New Standard for Technology AdoptionAs IT becomes a dominant component of how businesses run and compete, organizations need to lower the cost of implementing applications and introducing new application features. In the past, rolling out new code often required creating a test bed system, moving beta code to a separate system for user feedback, and--once all the revisions were made--moving version one of the software onto production systems, where business users could finally get the needed new features. Oracle Fusion Applications will use a dedicated setup manager application to streamline this process. First, the setup manager will help scope out the project, querying users about their requirements. "From those questions and answers we determine the steps and the order of those steps that will enable that task," Miranda says. Next, system utilities will assign tasks to owners, track completion status, and monitor the overall status of a programming effort. Oracle Fusion Applications can then recommend Web services that allow users to migrate setup choices and steps across all the various deployments of the application. Those setup capabilities automate the migration from test systems to production systems, as well as between different business units that may be using the same application. "The self-service ability of the setup manager helps business users change setups with very little intervention from the IT team," says Ravi Kumar, vice president at IT services company Infosys. "That to me is a big difference from how we've viewed enterprise applications before." For additional flexibility, organizations will be able to adopt Oracle Fusion Applications modules in either of two modes: a single-instance alternative uses one database for all Oracle Fusion Applications, while a "pillar mode" creates separate databases to underpin each application. This means IT departments running any one of Oracle's applications or even third-party applications can plug Oracle Fusion Applications modules into their environment and see additional business value created on top of their existing systems. And Oracle Fusion Applications offer a hybrid approach to deployment. The applications are all software-as-a-service-ready, so customers can choose on-premises, public or private cloud, or a combination of these to suit their business needs. It's that combination of flexibility and a roadmap for the future that may be the biggest game changer of all. "The Oracle Fusion Applications architecture allows us to migrate our company at a pace that's consistent with our business strategy, whereas before we might have had to do it with a massive upgrade," says Macrie of Ingersoll Rand. "We're looking forward to that architecture to really give us more flexibility in how we migrate over time." For More InformationUser Input Key to the Success of Oracle Fusion ApplicationsTransforming Coexistence into Strategic ValueUnder the HoodOracle Fusion ApplicationsOracle Service-Oriented Architecture  

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  • Simple Branching and Merging with SVN

    Its a good idea not to do too much work without checking something into source control.  By too much work I mean typically on the order of a couple of hours at most, and certainly its a good practice to check in anything you have before you leave the office for the day.  But what if your changes break the build (on the build server you do have a build server dont you?) or would cause problems for others on your team if they get the latest code?  The solution with Subversion is branching and merging (incidentally, if youre using Microsoft Visual Studio Team System, you can shelve your changes and share shelvesets with others, which accomplishes many of the same things as branching and merging, but is a bit simpler to do). Getting Started Im going to assume you have Subversion installed along with the nearly ubiquitous client, TortoiseSVN.  See my previous post on installing SVN server if you want to get it set up real quick (you can put it on your workstation/laptop just to learn how it works easily enough). Overview When you know you are going to be working on something that you wont be able to check in quickly, its a good idea to start a branch.  Its also perfectly fine to create the branch after-the-fact (have you ever started something thinking it would be an hour and 4 hours later realized you were nowhere near done?).  In any event, the first thing you need to do is create a branch.  A branch is simply a copy of the current trunk (a typical subversion setup has root directories called trunk, tags, and branches its a good idea to keep this and to put your branches in the branches folder).  Once you have a new branch, you need to switch your working copy so that it is bound to your branch.  As you work,  you may want to merge in changes that are happening in the trunk to your branch, and ultimately when you are done youll want to merge your branch back into the trunk.  When done, you can delete your branch (or not, but it may add clutter).  To sum up: Create a new branch Switch your local working copy to the new branch Develop in the branch (commit changes, etc.) Merge changes from trunk into your branch Merge changes from branch into trunk Delete the branch Create a new branch From the root of your repository, right-click and select TortoiseSVN > Branch/tag as shown at right (click to enlarge).  This will bring up the Copy (Branch / Tag) interface.  By default the From WC at URL: should be pointing at the trunk of your repository.  I recommend (after ensuring that you have the latest version) that you choose to make the copy from the HEAD revision in the repository (the first radio button).  In the To URL: textbox, you should change the URL from /trunk to /branches/NAME_OF_BRANCH.  You can name the branch anything you like, but its often useful to give it your name (if its just for your use) or some useful information (such as a datestamp or a bug/issue ID from that it relates to, or perhaps just the name of the feature you are adding. When youre done with that, enter in a log message for your new branch.  If you want to immediately switch your local working copy to the new branch/tag, check the box at the bottom of the dialog (Switch working copy to new branch/tag).  You can see an example at right. Assuming everything works, you should very quickly see a window telling you the Copy finished, like the one shown below: Switch Local Working Copy to New Branch If you followed the instructions above and checked the box when you created your branch, you dont need to do this step.  However, if you have a branch that already exists and you would like to switch over to working on it, you can do so by using the Switch command.  Youll find it in the explorer context menu under TortoiseSVN > Switch: This brings up a dialog that shows you your current binding, and lets you enter in a new URL to switch to: In the screenshot above, you can see that Im currently bound to a branch, and so I could switch back to the trunk or to another branch.  If youre not sure what to enter here, you can click the [] next to the URL textbox to explore your repository and find the appropriate root URL to use.  Also, the dropdown will show you URLs that might be a good fit (such as the trunk of the current repository). Develop in the Branch Once you have created a branch and switched your working copy to use it,  you can make changes and Commit them as usual.  Your commits are now going into the branch, so they wont impact other users or the build server that are working off of the trunk (or their own branches).  In theory you can keep on doing this forever, but practically its a good idea to periodically merge the trunk into your branch, and/or keep your branches short-lived and merge them back into the trunk before they get too far out of sync. Merge Changes from Trunk into your Branch Once you have been working in a branch for a little while, change to the trunk will have occurred that youll want to merge into your branch.  Its much safer and easier to integrate changes in small increments than to wait for weeks or months and then try to merge in two very different codebases.  To perform the merge, simply go to the root of your branch working copy and right click, select TortoiseSVN->Merge.  Youll be presented with this dialog: In this case you want to leave the default setting, Merge a range of revisions.  Click Next.  Now choose the URL to merge from.  You should select the trunk of your current repository (which should be in the dropdownlist, or you can click the [] to browse your repository for the correct URL).  You can leave everything else blank since you want to merge everything: Click Next.  Again you can leave the default settings.  If you want to do something more granular than everything in the trunk, you can select a different Merge depth, to include merging just one item in the tree.  You can also perform a Test merge to see what changes will take place before you click Merge (which is often a good idea).  Heres what the dialog should look like before you click Merge: After clicking Merge (or Test merge) you should see a confirmation like this (it will say Test Only in the title if you click Test merge): Now you should build your solution, run all of your tests, and verify that your branch still works the way it should, given the updates that youve just integrated from the trunk.  Once everything works, Commit your changes, and then continue with your work on the branch.  Note that until you commit, nothing has actually changed in your branch on the server.  Other team members who may also be working in this branch wont be impacted, etc.  The Merge is purely a client-side operation until you perform a Commit. In a more real-world scenario, you may have conflicts.  When you do, youll be presented with a dialog like this one: Its up to you which option you want to go with.  The more frequently you Merge, the fewer of these youll have to deal with.  Also, be very sure that youre merging the right folders together.  If you try and merge your trunk with some subfolder in your branchs structure, youll end up with all kinds of conflicts and problems.  Fortunately, theyre only on your working copy (unless you commit them!) but if you see something like that, be sure to doublecheck your URL and your local file location. Merge Your Branch Back Into Trunk When youre done working in your branch, its time to pull it back into the trunk.  The first thing you should do is follow the previous steps instructions for merging the latest from the trunk into your branch.  This lets you ensure that what you have in your branch works correctly with the current trunk.  Once youve done that and committed your changes to your branch, youre ready to proceed with this step. Once youre confident your branch is good to go, you should go to its root folder and select TortoiseSVN->Merge (as above) from the explorer right-click menu.  This time, select Reintegrate a branch as shown below: Click Next.  Youll want it to merge with the trunk, which should be the default: Click Next. Leave the default settings: Click Test merge to see a test, and then if all looks good, click Merge.  Note that if you havent checked in your working copy changes, youll see something like this: If on the other hand things are successful: After this step, its likely you are finished working in your branch.  Dont forget to use the ToroiseSVN->Switch command to change your working copy back to the trunk. Delete the Branch You dont have to delete the branch, but over time your branches area of your repository will get cluttered, and in any event if theyre not actively being worked on the branches are just taking up space and adding to later confusion.  Keeping your branches limited to things youre actively working on is simply a good habit to get into, just like making sure your codebase itself remains tidy and not filled with old commented out bits of code. To delete the branch after youre finished with it, the simplest thing to do is choose TortoiseSVN->Repo Browser.  From there, assuming you did this from your branch, it should already be highlighted.  In any event, navigate to your branch in the treeview on the left, and then right-click and select Delete.  Enter a log message if youd like: Click OK, and its gone.  Dont be too afraid of this, though.  You can still get to the files by viewing the log for branches, and selecting a previous revision (anything before the delete action): If for some reason you needed something that was previously in this branch, you could easily get back to any changeset you checked in, so you should have absolutely no fear when it comes to deleting branches youre done with.   Resources If youre using Eclipse, theres a nice write-up of the steps required by Zach Cox that I found helpful here. 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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  • protobuf-net: Issues deserializing DataMember fields in lieu of read-only property

    - by Paul Smith
    I'm having issues deserializing certain properties of ORM-generated entities using protobuf-net. I suspect something in the way the ORM manages serialization attributes on read-only properties (uses public backing fields with DataMember attributes & [de]serializes) those instead of the corresponding read-only property, which has an IgnoreDataMember attribute). Guid properties might have issues of their own, but the field vs. property thing is my working theory now. Here's a simplified example of the code. Say I have a class, Account with an AccountID read-only guid, and an AccountName read-write string. I serialize & immediately deserialize a clone. In this scenario I get one of two results (depending on the entity, haven't isolated the specific commonality yet). The deserialized clone either: ...has a different AccountID from the original, or ...throws an Incorrect wire-type deserializing Guid exception while deserializing. Here's example usage... Account acct = new Account() { AccountName = "Bob's Checking" }; Debug.WriteLine(acct.AccountID.ToString()); using (MemoryStream ms = new MemoryStream()) { ProtoBuf.Serializer.Serialize<Account>(ms, acct); Debug.WriteLine(Encoding.UTF8.GetString(ms.GetBuffer())); ms.Position = 0; Account clone = ProtoBuf.Serializer.Deserialize<Account>(ms); Debug.WriteLine(clone.AccountID.ToString()); } And here's an example ORM'd class (simplified; hopefully haven't removed the cause of the issue in the process). Uses a shell game to deserialize read-only properties by exposing the backing field ("can't write" essentially becomes "shouldn't write," but we can scan code for instances of assigning to these fields, so the hack works for our purposes): [DataContract()] [Serializable()] public partial class Account { public Account() { _accountID = Guid.NewGuid(); } [XmlAttribute("AccountID")] [DataMember(Name = "AccountID", Order = 0)] public Guid _accountID; /// <summary> /// A read-only property; XML, JSON and DataContract serializers all seem /// to correctly recognize the public backing field when deserializing: /// </summary> [IgnoreDataMember] [XmlIgnore] public Guid AccountID { get { return this._accountID; } } [IgnoreDataMember] protected string _accountName; [DataMember(Name = "AccountName", Order = 1)] [XmlAttribute] public string AccountName { get { return this._accountName; } set { this._accountName = value; } } } XML, JSON and DataContract serializers all seem to serialize / deserialize matching object graphs here, so this attribute arrangement apparently causes those serializers to correctly assign to the public backing field when deserializing. I've tried protobuf-net with lists vs. single instances, different prefix styles, etc., but always either get the 'incorrect wire type ... Guid' exception, or the Guid property (field) not deserializing correctly. So the specific questions are, is there a quick workaround for this, and/or is there an explanation for both of outcomes 1 & 2 above, and/or can protobuf-net somehow be corralled into behaving like WCF in cases like this (i.e. follow the same DataMember/IgnoreDataMember semantics)? We hope not to have to create a protobuf dependency directly in the entity layer; if that's the case, we'll probably create proxy DTO entities with all public properties having protobuf attributes. (This is a subjective issue I have with all declarative serialization models; it's a ubiquitous pattern, but IMO, "normal" should be to have objects and serialization contracts decoupled.) Thanks!

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  • protobuf-net: incorrect wire-type exception deserializing Guid properties

    - by Paul Smith
    I'm having issues deserializing certain Guid properties of ORM-generated entities using protobuf-net. Here's a simplified example of the code (reproduces most elements of the scenario, but doesn't reproduce the behavior; I can't expose our internal entities, so I'm looking for clues to account for the exception). Say I have a class, Account with an AccountID read-only guid, and an AccountName read-write string. I serialize & immediately deserialize a clone. Deserializing throws an Incorrect wire-type deserializing Guid exception while deserializing. Here's example usage... Account acct = new Account() { AccountName = "Bob's Checking" }; Debug.WriteLine(acct.AccountID.ToString()); using (MemoryStream ms = new MemoryStream()) { ProtoBuf.Serializer.Serialize<Account>(ms, acct); Debug.WriteLine(Encoding.UTF8.GetString(ms.GetBuffer())); ms.Position = 0; Account clone = ProtoBuf.Serializer.Deserialize<Account>(ms); Debug.WriteLine(clone.AccountID.ToString()); } And here's an example ORM'd class (simplified, but demonstrates the relevant semantics I can think of). Uses a shell game to deserialize read-only properties by exposing the backing field ("can't write" essentially becomes "shouldn't write," but we can scan code for instances of assigning to these fields, so the hack works for our purposes). Again, this does not reproduce the exception behavior; I'm looking for clues as to what could: [DataContract()] [Serializable()] public partial class Account { public Account() { _accountID = Guid.NewGuid(); } [XmlAttribute("AccountID")] [DataMember(Name = "AccountID", Order = 1)] public Guid _accountID; /// <summary> /// A read-only property; XML, JSON and DataContract serializers all seem /// to correctly recognize the public backing field when deserializing: /// </summary> [IgnoreDataMember] [XmlIgnore] public Guid AccountID { get { return this._accountID; } } [IgnoreDataMember] protected string _accountName; [DataMember(Name = "AccountName", Order = 2)] [XmlAttribute] public string AccountName { get { return this._accountName; } set { this._accountName = value; } } } XML, JSON and DataContract serializers all seem to serialize / deserialize these object graphs just fine, so the attribute arrangement basically works. I've tried protobuf-net with lists vs. single instances, different prefix styles, etc., but still always get the 'incorrect wire-type ... Guid' exception when deserializing. So the specific questions is, is there any known explanation / workaround for this? I'm at a loss trying to trace what circumstances (in the real code but not the example) could be causing it. We hope not to have to create a protobuf dependency directly in the entity layer; if that's the case, we'll probably create proxy DTO entities with all public properties having protobuf attributes. (This is a subjective issue I have with all declarative serialization models; it's a ubiquitous pattern & I understand why it arose, but IMO, if we can put a man on the moon, then "normal" should be to have objects and serialization contracts decoupled. ;-) ) Thanks!

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  • Domain Validation in a CQRS architecture

    - by Jupaol
    Basically I want to know if there is a better way to validate my domain entities. This is how I am planning to do it but I would like your opinion The first approach I considered was: class Customer : EntityBase<Customer> { public void ChangeEmail(string email) { if(string.IsNullOrWhitespace(email)) throw new DomainException(“...”); if(!email.IsEmail()) throw new DomainException(); if(email.Contains(“@mailinator.com”)) throw new DomainException(); } } I actually do not like this validation because even when I am encapsulating the validation logic in the correct entity, this is violating the Open/Close principle (Open for extension but Close for modification) and I have found that violating this principle, code maintenance becomes a real pain when the application grows up in complexity. Why? Because domain rules change more often than we would like to admit, and if the rules are hidden and embedded in an entity like this, they are hard to test, hard to read, hard to maintain but the real reason why I do not like this approach is: if the validation rules change, I have to come and edit my domain entity. This has been a really simple example but in RL the validation could be more complex So following the philosophy of Udi Dahan, making roles explicit, and the recommendation from Eric Evans in the blue book, the next try was to implement the specification pattern, something like this class EmailDomainIsAllowedSpecification : IDomainSpecification<Customer> { private INotAllowedEmailDomainsResolver invalidEmailDomainsResolver; public bool IsSatisfiedBy(Customer customer) { return !this.invalidEmailDomainsResolver.GetInvalidEmailDomains().Contains(customer.Email); } } But then I realize that in order to follow this approach I had to mutate my entities first in order to pass the value being valdiated, in this case the email, but mutating them would cause my domain events being fired which I wouldn’t like to happen until the new email is valid So after considering these approaches, I came out with this one, since I am going to implement a CQRS architecture: class EmailDomainIsAllowedValidator : IDomainInvariantValidator<Customer, ChangeEmailCommand> { public void IsValid(Customer entity, ChangeEmailCommand command) { if(!command.Email.HasValidDomain()) throw new DomainException(“...”); } } Well that’s the main idea, the entity is passed to the validator in case we need some value from the entity to perform the validation, the command contains the data coming from the user and since the validators are considered injectable objects they could have external dependencies injected if the validation requires it. Now the dilemma, I am happy with a design like this because my validation is encapsulated in individual objects which brings many advantages: easy unit test, easy to maintain, domain invariants are explicitly expressed using the Ubiquitous Language, easy to extend, validation logic is centralized and validators can be used together to enforce complex domain rules. And even when I know I am placing the validation of my entities outside of them (You could argue a code smell - Anemic Domain) but I think the trade-off is acceptable But there is one thing that I have not figured out how to implement it in a clean way. How should I use this components... Since they will be injected, they won’t fit naturally inside my domain entities, so basically I see two options: Pass the validators to each method of my entity Validate my objects externally (from the command handler) I am not happy with the option 1 so I would explain how I would do it with the option 2 class ChangeEmailCommandHandler : ICommandHandler<ChangeEmailCommand> { public void Execute(ChangeEmailCommand command) { private IEnumerable<IDomainInvariantValidator> validators; // here I would get the validators required for this command injected, and in here I would validate them, something like this using (var t = this.unitOfWork.BeginTransaction()) { var customer = this.unitOfWork.Get<Customer>(command.CustomerId); this.validators.ForEach(x =. x.IsValid(customer, command)); // here I know the command is valid // the call to ChangeEmail will fire domain events as needed customer.ChangeEmail(command.Email); t.Commit(); } } } Well this is it. Can you give me your thoughts about this or share your experiences with Domain entities validation EDIT I think it is not clear from my question, but the real problem is: Hiding the domain rules has serious implications in the future maintainability of the application, and also domain rules change often during the life-cycle of the app. Hence implementing them with this in mind would let us extend them easily. Now imagine in the future a rules engine is implemented, if the rules are encapsulated outside of the domain entities, this change would be easier to implement

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  • What does the `forall` keyword in Haskell/GHC do?

    - by JUST MY correct OPINION
    I've been banging my head on this one for (quite literally) years now. I'm beginning to kinda/sorta understand how the foreach keyword is used in so-called "existential types" like this: data ShowBox = forall s. Show s => SB s (This despite the confusingly-worded explanations of it in the fragments found all around the web.) This is only a subset, however, of how foreach is used and I simply cannot wrap my mind around its use in things like this: runST :: forall a. (forall s. ST s a) -> a Or explaining why these are different: foo :: (forall a. a -> a) -> (Char,Bool) bar :: forall a. ((a -> a) -> (Char, Bool)) Or the whole RankNTypes stuff that breaks my brain when "explained" in a way that makes me want to do that Samuel L. Jackson thing from Pulp Fiction. (Don't follow that link if you're easily offended by strong language.) The problem, really, is that I'm a dullard. I can't fathom the chicken scratchings (some call them "formulae") of the elite mathematicians that created this language seeing as my university years are over two decades behind me and I never actually had to put what I learnt into use in practice. I also tend to prefer clear, jargon-free English rather than the kinds of language which are normal in academic environments. Most of the explanations I attempt to read on this (the ones I can find through search engines) have these problems: They're incomplete. They explain one part of the use of this keyword (like "existential types") which makes me feel happy until I read code that uses it in a completely different way (like runST, foo and bar above). They're densely packed with assumptions that I've read the latest in whatever branch of discrete math, category theory or abstract algebra is popular this week. (If I never read the words "consult the paper whatever for details of implementation" again, it will be too soon.) They're written in ways that frequently turn even simple concepts into tortuously twisted and fractured grammar and semantics. (I suspect that the last two items are the biggest problem. I wouldn't know, though, since I'm too much a dullard to comprehend them.) It's been asked why Haskell never really caught on in industry. I suspect, in my own humble, unintelligent way, that my experience in figuring out one stupid little keyword -- a keyword that is increasingly ubiquitous in the libraries being written these days -- are also part of the answer to that question. It's hard for a language to catch on when even its individual keywords cause years-long quests to comprehend. Years-long quests which end in failure. So... On to the actual question. Can anybody completely explain the foreach keyword in clear, plain English (or, if it exists somewhere, point to such a clear explanation which I've missed) that doesn't assume I'm a mathematician steeped in the jargon?

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  • Var null and not an object when using document.getElementById

    - by Dean
    Hi, I'm doing some work in HTML and JQuery. I have a problem of my textarea and submit button not appearing after the radio button is selected. My HTML looks like this: <html> <head><title>Publications Database | Which spotlight for Publications</title> <script type="text/javascript" src="./jquery.js"></script> <script src="./addSpotlight.js" type="text/javascript" charset="utf-8"></script> </head> <body> <div class="wrapper"> <div class="header"> <div class="headerText">Which spotlight for Publications</div> </div> <div class="mainContent"> <p>Please select the publication that you would like to make the spotlight of this month:</p> <form action="addSpotlight" method="POST" id="form" name="form"> <div class="div29" id="div29"><input type="radio" value="29" name="publicationIDs" >A System For Dynamic Server Allocation in Application Server Clusters, IEEE International Symposium on Parallel and Distributed Processsing with Applications, 2008 </div> <div class="div30" id="div30"><input type="radio" value="30" name="publicationIDs" >Analysing BitTorrent's Seeding Strategies, 7th IEEE/IFIP International Conference on Embedded and Ubiquitous Computing (EUC-09), 2009 </div> <div class="div31" id="div31"><input type="radio" value="31" name="publicationIDs" >The Effect of Server Reallocation Time in Dynamic Resource Allocation, UK Performance Engineering Workshop 2009, 2009 </div> <div class="div32" id="div32"><input type="radio" value="32" name="publicationIDs" >idk, hello, 1992 </div> <div class="div33" id="div33"><input type="radio" value="33" name="publicationIDs" >sad, safg, 1992 </div> <div class="abstractWriteup" id="abstractWriteup"><textarea name="abstract"></textarea> <input type="submit" value="Add Spotlight"></div> </form> </div> </div> </body> </html> My javascript looks like this: $(document).ready( function() { $('.abstractWriteup').hide(); addAbstract(); }); function addAbstract() { var abstractWU = document.getElementById('.abstractWriteup'); $("input[name='publicationIDs']").change(function() { var abstractWU = document.getElementById('.abstractWriteup'); var classNameOfSelected = $("input[name='publicationIDs']").val(); var radioSelected = document.getElementById("div"+classNameOfSelected); var parentDiv = radioSelected.parentNode; parentDiv.insertBefore(radioSelected, abstractWU.nextSibling); $('.abstractWriteup').show(); });}; I have developed this by using Node#insertBefore. When I have had it working it has been rearranging the radio buttons. Thanks in Advance Dean

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  • Office 2010: It&rsquo;s not just DOC(X) and XLS(X)

    - by andrewbrust
    Office 2010 has released to manufacturing.  The bits have left the (product team’s) building.  Will you upgrade? This version of Office is officially numbered 14, a designation that correlates with the various releases, through the years, of Microsoft Word.  There were six major versions of Word for DOS, during whose release cycles came three 16-bit Windows versions.  Then, starting with Word 95 and counting through Word 2007, there have been six more versions – all for the 32-bit Windows platform.  Skip version 13 to ward off folksy bad luck (and, perhaps, the bugs that could come with it) and that brings us to version 14, which includes implementations for both 32- and 64-bit Windows platforms.  We’ve come a long way baby.  Or have we? As it does every three years or so, debate will now start to rage on over whether we need a “14th” version the PC platform’s standard word processor, or a “13th” version of the spreadsheet.  If you accept the premise of that question, then you may be on a slippery slope toward answering it in the negative.  Thing is, that premise is valid for certain customers and not others. The Microsoft Office product has morphed from one that offered core word processing, spreadsheet, presentation and email functionality to a suite of applications that provides unique, new value-added features, and even whole applications, in the context of those core services.  The core apps thus grow in mission: Excel is a BI tool.  Word is a collaborative editorial system for the production of publications.  PowerPoint is a media production platform for for live presentations and, increasingly, for delivering more effective presentations online.  Outlook is a time and task management system.  Access is a rich client front-end for data-driven self-service SharePoint applications.  OneNote helps you capture ideas, corral random thoughts in a semi-structured way, and then tie them back to other, more rigidly structured, Office documents. Google Docs and other cloud productivity platforms like Zoho don’t really do these things.  And there is a growing chorus of voices who say that they shouldn’t, because those ancillary capabilities are over-engineered, over-produced and “under-necessary.”  They might say Microsoft is layering on superfluous capabilities to avoid admitting that Office’s core capabilities, the ones people really need, have become commoditized. It’s hard to take sides in that argument, because different people, and the different companies that employ them, have different needs.  For my own needs, it all comes down to three basic questions: will the new version of Office save me time, will it make the mundane parts of my job easier, and will it augment my services to customers?  I need my time back.  I need to spend more of it with my family, and more of it focusing on my own core capabilities rather than the administrative tasks around them.  And I also need my customers to be able to get more value out of the services I provide. Help me triage my inbox, help me get proposals done more quickly and make them easier to read.  Let me get my presentations done faster, make them more effective and make it easier for me to reuse materials from other presentations.  And, since I’m in the BI and data business, help me and my customers manage data and analytics more easily, both on the desktop and online. Those are my criteria.  And, with those in mind, Office 2010 is looking like a worthwhile upgrade.  Perhaps it’s not earth-shattering, but it offers a combination of incremental improvements and a few new major capabilities that I think are quite compelling.  I provide a brief roundup of them here.  It’s admittedly arbitrary and not comprehensive, but I think it tells the Office 2010 story effectively. Across the Suite More than any other, this release of Office aims to give collaboration a real workout.  In certain apps, for the first time, documents can be opened simultaneously by multiple users, with colleagues’ changes appearing in near real-time.  Web-browser-based versions of Word, Excel, PowerPoint and OneNote will be available to extend collaboration to contributors who are off the corporate network. The ribbon user interface is now more pervasive (for example, it appears in OneNote and in Outlook’s main window).  It’s also customizable, allowing users to add, easily, buttons and options of their choosing, into new tabs, or into new groups within existing tabs. Microsoft has also taken the File menu (which was the “Office Button” menu in the 2007 release) and made it into a full-screen “Backstage” view where document-wide operations, like saving, printing and online publishing are performed. And because, more and more, heavily formatted content is cut and pasted between documents and applications, Office 2010 makes it easier to manage the retention or jettisoning of that formatting right as the paste operation is performed.  That’s much nicer than stripping it off, or adding it back, afterwards. And, speaking of pasting, a number of Office apps now make it especially easy to insert screenshots within their documents.  I know that’s useful to me, because I often document or critique applications and need to show them in action.  For the vast majority of users, I expect that this feature will be more useful for capturing snapshots of Web pages, but we’ll have to see whether this feature becomes popular.   Excel At first glance, Excel 2010 looks and acts nearly identically to the 2007 version.  But additional glances are necessary.  It’s important to understand that lots of people in the working world use Excel as more of a database, analytics and mathematical modeling tool than merely as a spreadsheet.  And it’s also important to understand that Excel wasn’t designed to handle such workloads past a certain scale.  That all changes with this release. The first reason things change is that Excel has been tuned for performance.  It’s been optimized for multi-threaded operation; previously lengthy processes have been shortened, especially for large data sets; more rows and columns are allowed and, for the first time, Excel (and the rest of Office) is available in a 64-bit version.  For Excel, this means users can take advantage of more than the 2GB of memory that the 32-bit version is limited to. On the analysis side, Excel 2010 adds Sparklines (tiny charts that fit into a single cell and can therefore be presented down an entire column or across a row) and Slicers (a more user-friendly filter mechanism for PivotTables and charts, which visually indicates what the filtered state of a given data member is).  But most important, Excel 2010 supports the new PowerPIvot add-in which brings true self-service BI to Office.  PowerPivot allows users to import data from almost anywhere, model it, and then analyze it.  Rather than forcing users to build “spreadmarts” or use corporate-built data warehouses, PowerPivot models function as true columnar, in-memory OLAP cubes that can accommodate millions of rows of data and deliver fast drill-down performance. And speaking of OLAP, Excel 2010 now supports an important Analysis Services OLAP feature called write-back.  Write-back is especially useful in financial forecasting scenarios for which Excel is the natural home.  Support for write-back is long overdue, but I’m still glad it’s there, because I had almost given up on it.   PowerPoint This version of PowerPoint marks its progression from a presentation tool to a video and photo editing and production tool.  Whether or not it’s successful in this pursuit, and if offering this is even a sensible goal, is another question. Regardless, the new capabilities are kind of interesting.  A greatly enhanced set of slide transitions with 3D effects; in-product photo and video editing; accommodation of embedded videos from services such as YouTube; and the ability to save a presentation as a video each lay testimony to PowerPoint’s transformation into a media tool and away from a pure presentation tool. These capabilities also recognize the importance of the Web as both a source for materials and a channel for disseminating PowerPoint output. Congruent with that is PowerPoint’s new ability to broadcast a slide presentation, using a quickly-generated public URL, without involving the hassle or expense of a Web meeting service like GoToMeeting or Microsoft’s own LiveMeeting.  Slides presented through this broadcast feature retain full color fidelity and transitions and animations are preserved as well.   Outlook Microsoft’s ubiquitous email/calendar/contact/task management tool gains long overdue speed improvements, especially against POP3 email accounts.  Outlook 2010 also supports multiple Exchange accounts, rather than just one; tighter integration with OneNote; and a new Social Connector providing integration with, and presence information from, online social network services like LinkedIn and Facebook (not to mention Windows Live).  A revamped conversation view now includes messages that are part of a given thread regardless of which folder they may be stored in. I don’t know yet how well the Social Connector will work or whether it will keep Outlook relevant to those who live on Facebook and LinkedIn.  But among the other features, there’s very little not to like.   OneNote To me, OneNote is the part of Office that just keeps getting better.  There is one major caveat to this, which I’ll cover in a moment, but let’s first catalog what new stuff OneNote 2010 brings.  The best part of OneNote, is the way each of its versions have managed hierarchy: Notebooks have sections, sections have pages, pages have sub pages, multiple notes can be contained in either, and each note supports infinite levels of indentation.  None of that is new to 2010, but the new version does make creation of pages and subpages easier and also makes simple work out of promoting and demoting pages from sub page to full page status.  And relationships between pages are quite easy to create now: much like a Wiki, simply typing a page’s name in double-square-brackets (“[[…]]”) creates a link to it. OneNote is also great at integrating content outside of its notebooks.  With a new Dock to Desktop feature, OneNote becomes aware of what window is displayed in the rest of the screen and, if it’s an Office document or a Web page, links the notes you’re typing, at the time, to it.  A single click from your notes later on will bring that same document or Web page back on-screen.  Embedding content from Web pages and elsewhere is also easier.  Using OneNote’s Windows Key+S combination to grab part of the screen now allows you to specify the destination of that bitmap instead of automatically creating a new note in the Unfiled Notes area.  Using the Send to OneNote buttons in Internet Explorer and Outlook result in the same choice. Collaboration gets better too.  Real-time multi-author editing is better accommodated and determining author lineage of particular changes is easily carried out. My one pet peeve with OneNote is the difficulty using it when I’m not one a Windows PC.  OneNote’s main competitor, Evernote, while I believe inferior in terms of features, has client versions for PC, Mac, Windows Mobile, Android, iPhone, iPad and Web browsers.  Since I have an Android phone and an iPad, I am practically forced to use it.  However, the OneNote Web app should help here, as should a forthcoming version of OneNote for Windows Phone 7.  In the mean time, it turns out that using OneNote’s Email Page ribbon button lets you move a OneNote page easily into EverNote (since every EverNote account gets a unique email address for adding notes) and that Evernote’s Email function combined with Outlook’s Send to OneNote button (in the Move group of the ribbon’s Home tab) can achieve the reverse.   Access To me, the big change in Access 2007 was its tight integration with SharePoint lists.  Access 2010 and SharePoint 2010 continue this integration with the introduction of SharePoint’s Access Services.  Much as Excel Services provides a SharePoint-hosted experience for viewing (and now editing) Excel spreadsheet, PivotTable and chart content, Access Services allows for SharePoint browser-hosted editing of Access data within the forms that are built in the Access client itself. To me this makes all kinds of sense.  Although it does beg the question of where to draw the line between Access, InfoPath, SharePoint list maintenance and SharePoint 2010’s new Business Connectivity Services.  Each of these tools provide overlapping data entry and data maintenance functionality. But if you do prefer Access, then you’ll like  things like templates and application parts that make it easier to get off the blank page.  These features help you quickly get tables, forms and reports built out.  To make things look nice, Access even gets its own version of Excel’s Conditional Formatting feature, letting you add data bars and data-driven text formatting.   Word As I said at the beginning of this post, upgrades to Office are about much more than enhancing the suite’s flagship word processing application. So are there any enhancements in Word worth mentioning?  I think so.  The most important one has to be the collaboration features.  Essentially, when a user opens a Word document that is in a SharePoint document library (or Windows Live SkyDrive folder), rather than the whole document being locked, Word has the ability to observe more granular locks on the individual paragraphs being edited.  Word also shows you who’s editing what and its Save function morphs into a sync feature that both saves your changes and loads those made by anyone editing the document concurrently. There’s also a new navigation pane that lets you manage sections in your document in much the same way as you manage slides in a PowerPoint deck.  Using the navigation pane, you can reorder sections, insert new ones, or promote and demote sections in the outline hierarchy.  Not earth shattering, but nice.   Other Apps and Summarized Findings What about InfoPath, Publisher, Visio and Project?  I haven’t looked at them yet.  And for this post, I think that’s fine.  While those apps (and, arguably, Access) cater to specific tasks, I think the apps we’ve looked at in this post service the general purpose needs of most users.  And the theme in those 2010 apps is clear: collaboration is key, the Web and productivity are indivisible, and making data and analytics into a self-service amenity is the way to go.  But perhaps most of all, features are still important, as long as they get you through your day faster, rather than adding complexity for its own sake.  I would argue that this is true for just about every product Microsoft makes: users want utility, not complexity.

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