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  • Quick guide to Oracle IRM 11g: Classification design

    - by Simon Thorpe
    Quick guide to Oracle IRM 11g indexThis is the final article in the quick guide to Oracle IRM. If you've followed everything prior you will now have a fully functional and tested Information Rights Management service. It doesn't matter if you've been following the 10g or 11g guide as this next article is common to both. ContentsWhy this is the most important part... Understanding the classification and standard rights model Identifying business use cases Creating an effective IRM classification modelOne single classification across the entire businessA context for each and every possible granular use caseWhat makes a good context? Deciding on the use of roles in the context Reviewing the features and security for context roles Summary Why this is the most important part...Now the real work begins, installing and getting an IRM system running is as simple as following instructions. However to actually have an IRM technology easily protecting your most sensitive information without interfering with your users existing daily work flows and be able to scale IRM across the entire business, requires thought into how confidential documents are created, used and distributed. This article is going to give you the information you need to ask the business the right questions so that you can deploy your IRM service successfully. The IRM team here at Oracle have over 10 years of experience in helping customers and it is important you understand the following to be successful in securing access to your most confidential information. Whatever you are trying to secure, be it mergers and acquisitions information, engineering intellectual property, health care documentation or financial reports. No matter what type of user is going to access the information, be they employees, contractors or customers, there are common goals you are always trying to achieve.Securing the content at the earliest point possible and do it automatically. Removing the dependency on the user to decide to secure the content reduces the risk of mistakes significantly and therefore results a more secure deployment. K.I.S.S. (Keep It Simple Stupid) Reduce complexity in the rights/classification model. Oracle IRM lets you make changes to access to documents even after they are secured which allows you to start with a simple model and then introduce complexity once you've understood how the technology is going to be used in the business. After an initial learning period you can review your implementation and start to make informed decisions based on user feedback and administration experience. Clearly communicate to the user, when appropriate, any changes to their existing work practice. You must make every effort to make the transition to sealed content as simple as possible. For external users you must help them understand why you are securing the documents and inform them the value of the technology to both your business and them. Before getting into the detail, I must pay homage to Martin White, Vice President of client services in SealedMedia, the company Oracle acquired and who created Oracle IRM. In the SealedMedia years Martin was involved with every single customer and was key to the design of certain aspects of the IRM technology, specifically the context model we will be discussing here. Listening carefully to customers and understanding the flexibility of the IRM technology, Martin taught me all the skills of helping customers build scalable, effective and simple to use IRM deployments. No matter how well the engineering department designed the software, badly designed and poorly executed projects can result in difficult to use and manage, and ultimately insecure solutions. The advice and information that follows was born with Martin and he's still delivering IRM consulting with customers and can be found at www.thinkers.co.uk. It is from Martin and others that Oracle not only has the most advanced, scalable and usable document security solution on the market, but Oracle and their partners have the most experience in delivering successful document security solutions. Understanding the classification and standard rights model The goal of any successful IRM deployment is to balance the increase in security the technology brings without over complicating the way people use secured content and avoid a significant increase in administration and maintenance. With Oracle it is possible to automate the protection of content, deploy the desktop software transparently and use authentication methods such that users can open newly secured content initially unaware the document is any different to an insecure one. That is until of course they attempt to do something for which they don't have any rights, such as copy and paste to an insecure application or try and print. Central to achieving this objective is creating a classification model that is simple to understand and use but also provides the right level of complexity to meet the business needs. In Oracle IRM the term used for each classification is a "context". A context defines the relationship between.A group of related documents The people that use the documents The roles that these people perform The rights that these people need to perform their role The context is the key to the success of Oracle IRM. It provides the separation of the role and rights of a user from the content itself. Documents are sealed to contexts but none of the rights, user or group information is stored within the content itself. Sealing only places information about the location of the IRM server that sealed it, the context applied to the document and a few other pieces of metadata that pertain only to the document. This important separation of rights from content means that millions of documents can be secured against a single classification and a user needs only one right assigned to be able to access all documents. If you have followed all the previous articles in this guide, you will be ready to start defining contexts to which your sensitive information will be protected. But before you even start with IRM, you need to understand how your own business uses and creates sensitive documents and emails. Identifying business use cases Oracle is able to support multiple classification systems, but usually there is one single initial need for the technology which drives a deployment. This need might be to protect sensitive mergers and acquisitions information, engineering intellectual property, financial documents. For this and every subsequent use case you must understand how users create and work with documents, to who they are distributed and how the recipients should interact with them. A successful IRM deployment should start with one well identified use case (we go through some examples towards the end of this article) and then after letting this use case play out in the business, you learn how your users work with content, how well your communication to the business worked and if the classification system you deployed delivered the right balance. It is at this point you can start rolling the technology out further. Creating an effective IRM classification model Once you have selected the initial use case you will address with IRM, you need to design a classification model that defines the access to secured documents within the use case. In Oracle IRM there is an inbuilt classification system called the "context" model. In Oracle IRM 11g it is possible to extend the server to support any rights classification model, but the majority of users who are not using an application integration (such as Oracle IRM within Oracle Beehive) are likely to be starting out with the built in context model. Before looking at creating a classification system with IRM, it is worth reviewing some recognized standards and methods for creating and implementing security policy. A very useful set of documents are the ISO 17799 guidelines and the SANS security policy templates. First task is to create a context against which documents are to be secured. A context consists of a group of related documents (all top secret engineering research), a list of roles (contributors and readers) which define how users can access documents and a list of users (research engineers) who have been given a role allowing them to interact with sealed content. Before even creating the first context it is wise to decide on a philosophy which will dictate the level of granularity, the question is, where do you start? At a department level? By project? By technology? First consider the two ends of the spectrum... One single classification across the entire business Imagine that instead of having separate contexts, one for engineering intellectual property, one for your financial data, one for human resources personally identifiable information, you create one context for all documents across the entire business. Whilst you may have immediate objections, there are some significant benefits in thinking about considering this. Document security classification decisions are simple. You only have one context to chose from! User provisioning is simple, just make sure everyone has a role in the only context in the business. Administration is very low, if you assign rights to groups from the business user repository you probably never have to touch IRM administration again. There are however some obvious downsides to this model.All users in have access to all IRM secured content. So potentially a sales person could access sensitive mergers and acquisition documents, if they can get their hands on a copy that is. You cannot delegate control of different documents to different parts of the business, this may not satisfy your regulatory requirements for the separation and delegation of duties. Changing a users role affects every single document ever secured. Even though it is very unlikely a business would ever use one single context to secure all their sensitive information, thinking about this scenario raises one very important point. Just having one single context and securing all confidential documents to it, whilst incurring some of the problems detailed above, has one huge value. Once secured, IRM protected content can ONLY be accessed by authorized users. Just think of all the sensitive documents in your business today, imagine if you could ensure that only everyone you trust could open them. Even if an employee lost a laptop or someone accidentally sent an email to the wrong recipient, only the right people could open that file. A context for each and every possible granular use case Now let's think about the total opposite of a single context design. What if you created a context for each and every single defined business need and created multiple contexts within this for each level of granularity? Let's take a use case where we need to protect engineering intellectual property. Imagine we have 6 different engineering groups, and in each we have a research department, a design department and manufacturing. The company information security policy defines 3 levels of information sensitivity... restricted, confidential and top secret. Then let's say that each group and department needs to define access to information from both internal and external users. Finally add into the mix that they want to review the rights model for each context every financial quarter. This would result in a huge amount of contexts. For example, lets just look at the resulting contexts for one engineering group. Q1FY2010 Restricted Internal - Engineering Group 1 - Research Q1FY2010 Restricted Internal - Engineering Group 1 - Design Q1FY2010 Restricted Internal - Engineering Group 1 - Manufacturing Q1FY2010 Restricted External- Engineering Group 1 - Research Q1FY2010 Restricted External - Engineering Group 1 - Design Q1FY2010 Restricted External - Engineering Group 1 - Manufacturing Q1FY2010 Confidential Internal - Engineering Group 1 - Research Q1FY2010 Confidential Internal - Engineering Group 1 - Design Q1FY2010 Confidential Internal - Engineering Group 1 - Manufacturing Q1FY2010 Confidential External - Engineering Group 1 - Research Q1FY2010 Confidential External - Engineering Group 1 - Design Q1FY2010 Confidential External - Engineering Group 1 - Manufacturing Q1FY2010 Top Secret Internal - Engineering Group 1 - Research Q1FY2010 Top Secret Internal - Engineering Group 1 - Design Q1FY2010 Top Secret Internal - Engineering Group 1 - Manufacturing Q1FY2010 Top Secret External - Engineering Group 1 - Research Q1FY2010 Top Secret External - Engineering Group 1 - Design Q1FY2010 Top Secret External - Engineering Group 1 - Manufacturing Now multiply the above by 6 for each engineering group, 18 contexts. You are then creating/reviewing another 18 every 3 months. After a year you've got 72 contexts. What would be the advantages of such a complex classification model? You can satisfy very granular rights requirements, for example only an authorized engineering group 1 researcher can create a top secret report for access internally, and his role will be reviewed on a very frequent basis. Your business may have very complex rights requirements and mapping this directly to IRM may be an obvious exercise. The disadvantages of such a classification model are significant...Huge administrative overhead. Someone in the business must manage, review and administrate each of these contexts. If the engineering group had a single administrator, they would have 72 classifications to reside over each year. From an end users perspective life will be very confusing. Imagine if a user has rights in just 6 of these contexts. They may be able to print content from one but not another, be able to edit content in 2 contexts but not the other 4. Such confusion at the end user level causes frustration and resistance to the use of the technology. Increased synchronization complexity. Imagine a user who after 3 years in the company ends up with over 300 rights in many different contexts across the business. This would result in long synchronization times as the client software updates all your offline rights. Hard to understand who can do what with what. Imagine being the VP of engineering and as part of an internal security audit you are asked the question, "What rights to researchers have to our top secret information?". In this complex model the answer is not simple, it would depend on many roles in many contexts. Of course this example is extreme, but it highlights that trying to build many barriers in your business can result in a nightmare of administration and confusion amongst users. In the real world what we need is a balance of the two. We need to seek an optimum number of contexts. Too many contexts are unmanageable and too few contexts does not give fine enough granularity. What makes a good context? Good context design derives mainly from how well you understand your business requirements to secure access to confidential information. Some customers I have worked with can tell me exactly the documents they wish to secure and know exactly who should be opening them. However there are some customers who know only of the government regulation that requires them to control access to certain types of information, they don't actually know where the documents are, how they are created or understand exactly who should have access. Therefore you need to know how to ask the business the right questions that lead to information which help you define a context. First ask these questions about a set of documentsWhat is the topic? Who are legitimate contributors on this topic? Who are the authorized readership? If the answer to any one of these is significantly different, then it probably merits a separate context. Remember that sealed documents are inherently secure and as such they cannot leak to your competitors, therefore it is better sealed to a broad context than not sealed at all. Simplicity is key here. Always revert to the first extreme example of a single classification, then work towards essential complexity. If there is any doubt, always prefer fewer contexts. Remember, Oracle IRM allows you to change your mind later on. You can implement a design now and continue to change and refine as you learn how the technology is used. It is easy to go from a simple model to a more complex one, it is much harder to take a complex model that is already embedded in the work practice of users and try to simplify it. It is also wise to take a single use case and address this first with the business. Don't try and tackle many different problems from the outset. Do one, learn from the process, refine it and then take what you have learned into the next use case, refine and continue. Once you have a good grasp of the technology and understand how your business will use it, you can then start rolling out the technology wider across the business. Deciding on the use of roles in the context Once you have decided on that first initial use case and a context to create let's look at the details you need to decide upon. For each context, identify; Administrative rolesBusiness owner, the person who makes decisions about who may or may not see content in this context. This is often the person who wanted to use IRM and drove the business purchase. They are the usually the person with the most at risk when sensitive information is lost. Point of contact, the person who will handle requests for access to content. Sometimes the same as the business owner, sometimes a trusted secretary or administrator. Context administrator, the person who will enact the decisions of the Business Owner. Sometimes the point of contact, sometimes a trusted IT person. Document related rolesContributors, the people who create and edit documents in this context. Reviewers, the people who are involved in reviewing documents but are not trusted to secure information to this classification. This role is not always necessary. (See later discussion on Published-work and Work-in-Progress) Readers, the people who read documents from this context. Some people may have several of the roles above, which is fine. What you are trying to do is understand and define how the business interacts with your sensitive information. These roles obviously map directly to roles available in Oracle IRM. Reviewing the features and security for context roles At this point we have decided on a classification of information, understand what roles people in the business will play when administrating this classification and how they will interact with content. The final piece of the puzzle in getting the information for our first context is to look at the permissions people will have to sealed documents. First think why are you protecting the documents in the first place? It is to prevent the loss of leaking of information to the wrong people. To control the information, making sure that people only access the latest versions of documents. You are not using Oracle IRM to prevent unauthorized people from doing legitimate work. This is an important point, with IRM you can erect many barriers to prevent access to content yet too many restrictions and authorized users will often find ways to circumvent using the technology and end up distributing unprotected originals. Because IRM is a security technology, it is easy to get carried away restricting different groups. However I would highly recommend starting with a simple solution with few restrictions. Ensure that everyone who reasonably needs to read documents can do so from the outset. Remember that with Oracle IRM you can change rights to content whenever you wish and tighten security. Always return to the fact that the greatest value IRM brings is that ONLY authorized users can access secured content, remember that simple "one context for the entire business" model. At the start of the deployment you really need to aim for user acceptance and therefore a simple model is more likely to succeed. As time passes and users understand how IRM works you can start to introduce more restrictions and complexity. Another key aspect to focus on is handling exceptions. If you decide on a context model where engineering can only access engineering information, and sales can only access sales data. Act quickly when a sales manager needs legitimate access to a set of engineering documents. Having a quick and effective process for permitting other people with legitimate needs to obtain appropriate access will be rewarded with acceptance from the user community. These use cases can often be satisfied by integrating IRM with a good Identity & Access Management technology which simplifies the process of assigning users the correct business roles. The big print issue... Printing is often an issue of contention, users love to print but the business wants to ensure sensitive information remains in the controlled digital world. There are many cases of physical document loss causing a business pain, it is often overlooked that IRM can help with this issue by limiting the ability to generate physical copies of digital content. However it can be hard to maintain a balance between security and usability when it comes to printing. Consider the following points when deciding about whether to give print rights. Oracle IRM sealed documents can contain watermarks that expose information about the user, time and location of access and the classification of the document. This information would reside in the printed copy making it easier to trace who printed it. Printed documents are slower to distribute in comparison to their digital counterparts, so time sensitive information in printed format may present a lower risk. Print activity is audited, therefore you can monitor and react to users abusing print rights. Summary In summary it is important to think carefully about the way you create your context model. As you ask the business these questions you may get a variety of different requirements. There may be special projects that require a context just for sensitive information created during the lifetime of the project. There may be a department that requires all information in the group is secured and you might have a few senior executives who wish to use IRM to exchange a small number of highly sensitive documents with a very small number of people. Oracle IRM, with its very flexible context classification system, can support all of these use cases. The trick is to introducing the complexity to deliver them at the right level. In another article i'm working on I will go through some examples of how Oracle IRM might map to existing business use cases. But for now, this article covers all the important questions you need to get your IRM service deployed and successfully protecting your most sensitive information.

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  • using Generics in C# [closed]

    - by Uphaar Goyal
    I have started looking into using generics in C#. As an example what i have done is that I have an abstract class which implements generic methods. these generic methods take a sql query, a connection string and the Type T as parameters and then construct the data set, populate the object and return it back. This way each business object does not need to have a method to populate it with data or construct its data set. All we need to do is pass the type, the sql query and the connection string and these methods do the rest.I am providing the code sample here. I am just looking to discuss with people who might have a better solution to what i have done. using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Data; using System.Data.SqlClient; using MWTWorkUnitMgmtLib.Business; using System.Collections.ObjectModel; using System.Reflection; namespace MWTWorkUnitMgmtLib.TableGateway { public abstract class TableGateway { public TableGateway() { } protected abstract string GetConnection(); protected abstract string GetTableName(); public DataSet GetDataSetFromSql(string connectionString, string sql) { DataSet ds = null; using (SqlConnection connection = new SqlConnection(connectionString)) using (SqlCommand command = connection.CreateCommand()) { command.CommandText = sql; connection.Open(); using (ds = new DataSet()) using (SqlDataAdapter adapter = new SqlDataAdapter(command)) { adapter.Fill(ds); } } return ds; } public static bool ContainsColumnName(DataRow dr, string columnName) { return dr.Table.Columns.Contains(columnName); } public DataTable GetDataTable(string connString, string sql) { DataSet ds = GetDataSetFromSql(connString, sql); DataTable dt = null; if (ds != null) { if (ds.Tables.Count 0) { dt = ds.Tables[0]; } } return dt; } public T Construct(DataRow dr, T t) where T : class, new() { Type t1 = t.GetType(); PropertyInfo[] properties = t1.GetProperties(); foreach (PropertyInfo property in properties) { if (ContainsColumnName(dr, property.Name) && (dr[property.Name] != null)) property.SetValue(t, dr[property.Name], null); } return t; } public T GetByID(string connString, string sql, T t) where T : class, new() { DataTable dt = GetDataTable(connString, sql); DataRow dr = dt.Rows[0]; return Construct(dr, t); } public List GetAll(string connString, string sql, T t) where T : class, new() { List collection = new List(); DataTable dt = GetDataTable(connString, sql); foreach (DataRow dr in dt.Rows) collection.Add(Construct(dr, t)); return collection; } } }

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  • Learn about MySQL with the Authentic MySQL for Beginners course

    - by Antoinette O'Sullivan
    Learn about the MySQL Server and other MySQL products by taking the authentic MySQL for Beginners course. This course covers all the basics from MySQL download and installation, to relational database concepts and database design. This course is your first step to becoming a MySQL administrator. You can take this course through one of the following delivery types: Training-on-Demand: Start the class from your desk, at your base and within 24 hrs of registering. Read Ben Krug on Day 3 of his experience taking the MySQL for Beginners course Training-on-Demand option. Live-Virtual Class: Attend this live class from your own office - no travel required. Choose from a selection of events on the schedule to suit different timezones. Delivery languages include English and German. In-Class event: Attend this class in an education center. Events already on the schedule include:  Location  Date  Delivery Language  Mechelen, Belgium  14 January 2013  English  London, England  5 March 2013  English  Hamburg, Germany  25 March 2013  German  Munich, Germany  3 June 2013  German  Budapest, Hungary  5 February 2013  Hungary  Milan, Italy  11 February 2013  Italian  Rome, Italy  4 March 2013  Italian  Riga, Latvia  18 February 2013  Latvian  Amsterdam, Netherlands  21 May 2013  Dutch  Nieuwegein, Netherlands  18 February 2013  Dutch  Warsaw, Poland  18 February 2013  Polish  Lisbon, Portugal  25 March 2013  European Portugese  Porto, Portugal  25 March 2013  European Portugese  Barcelona, Spain  11 February 2013  Spanish  Madrid, Spain  22 April 2013  Spanish  Nairobi, Kenya  14 January 2013  English  Capetown, South Africa  22 July 2013  English  Pretoria, South Africa  22 April 2013  English  Petaling Jaya, Malaysia  28 January 2013  English  Ottawa, Canada  25 March 2013  English  Toronto, Canada  25 March 2013  English  Montreal, Canada 25 March 2013   English Mexico City, Mexico  14 January 2013   Spanish  San Pedro Garza Garcia, Mexico  5 February 2013  Spanish  Sao Paolo, Brazil  29 January 2013  Brazilian Portugese For more information on this or other courses on the authentic MySQL Curriculum, go to http://oracle.com/education/mysql. Note, many organizations deploy both Oracle Database and MySQL side by side to serve different needs, and as a database professional you can find training courses on both topics at Oracle University! Check out the upcoming Oracle Database training courses and MySQL training courses. Even if you're only managing Oracle Databases at this point of time, getting familiar with MySQL will broaden your career path with growing job demand.

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  • SQL SERVER – Challenge – Puzzle – Usage of FAST Hint

    - by pinaldave
    I was recently working with various SQL Server Hints. After working for a day on various hints, I realize that for one hint, I am not able to come up with good example. The hint is FAST. Let us look at the definition of the FAST hint from the Book On-Line. FAST number_rows Specifies that the query is optimized for fast retrieval of the first number_rows. This is a nonnegative integer. After the first number_rows are returned, the query continues execution and produces its full result set. Now the question is in what condition this hint can be useful. I have tried so many different combination, I have found this hint does not make much performance difference, infect I did not notice any change in time taken to load the resultset. I noticed that this hint does not change number of the page read to return result. Now when there is difference in performance is expected because if you read the what FAST hint does is that it only returns first few results FAST – which does not mean there will be difference in performance. I also understand that this hint gives the guidance/suggestions/hint to query optimizer that there are only 100 rows are in expected resultset. This tricking the optimizer to think there are only 100 rows and which (may) lead to render different execution plan than the one which it would have taken in normal case (without hint). Again, not necessarily, this will happen always. Now if you read above discussion, you will find that basic understanding of the hint is very clear to me but I still feel that I am missing something. Here are my questions: 1) In what condition this hint can be useful? What is the case, when someone want to see first few rows early because my experience suggests that when first few rows are rendered remaining rows are rendered as well. 2) Is there any way application can retrieve the fast fetched rows from SQL Server? 3) Do you use this hint in your application? Why? When? and How? Here are few examples I have attempted during the my experiment and found there is no difference in execution plan except its estimated number of rows are different leading optimizer think that the cost is less but in reality that is not the case. USE AdventureWorks GO SET STATISTICS IO ON SET STATISTICS TIME ON GO --------------------------------------------- -- Table Scan with Fast Hint SELECT * FROM Sales.SalesOrderDetail GO SELECT * FROM Sales.SalesOrderDetail OPTION (FAST 100) GO --------------------------------------------- -- Table Scan with Where on Index Key SELECT * FROM Sales.SalesOrderDetail WHERE OrderQty = 14 GO SELECT * FROM Sales.SalesOrderDetail WHERE OrderQty = 14 OPTION (FAST 100) GO --------------------------------------------- -- Table Scan with Where on Index Key SELECT * FROM Sales.SalesOrderDetail WHERE SalesOrderDetailID < 1000 GO SELECT * FROM Sales.SalesOrderDetail WHERE SalesOrderDetailID < 1000 OPTION (FAST 100) GO Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Syncing Data with a Server using Silverlight and HTTP Polling Duplex

    - by dwahlin
    Many applications have the need to stay in-sync with data provided by a service. Although web applications typically rely on standard polling techniques to check if data has changed, Silverlight provides several interesting options for keeping an application in-sync that rely on server “push” technologies. A few years back I wrote several blog posts covering different “push” technologies available in Silverlight that rely on sockets or HTTP Polling Duplex. We recently had a project that looked like it could benefit from pushing data from a server to one or more clients so I thought I’d revisit the subject and provide some updates to the original code posted. If you’ve worked with AJAX before in Web applications then you know that until browsers fully support web sockets or other duplex (bi-directional communication) technologies that it’s difficult to keep applications in-sync with a server without relying on polling. The problem with polling is that you have to check for changes on the server on a timed-basis which can often be wasteful and take up unnecessary resources. With server “push” technologies, data can be pushed from the server to the client as it changes. Once the data is received, the client can update the user interface as appropriate. Using “push” technologies allows the client to listen for changes from the data but stay 100% focused on client activities as opposed to worrying about polling and asking the server if anything has changed. Silverlight provides several options for pushing data from a server to a client including sockets, TCP bindings and HTTP Polling Duplex.  Each has its own strengths and weaknesses as far as performance and setup work with HTTP Polling Duplex arguably being the easiest to setup and get going.  In this article I’ll demonstrate how HTTP Polling Duplex can be used in Silverlight 4 applications to push data and show how you can create a WCF server that provides an HTTP Polling Duplex binding that a Silverlight client can consume.   What is HTTP Polling Duplex? Technologies that allow data to be pushed from a server to a client rely on duplex functionality. Duplex (or bi-directional) communication allows data to be passed in both directions.  A client can call a service and the server can call the client. HTTP Polling Duplex (as its name implies) allows a server to communicate with a client without forcing the client to constantly poll the server. It has the benefit of being able to run on port 80 making setup a breeze compared to the other options which require specific ports to be used and cross-domain policy files to be exposed on port 943 (as with sockets and TCP bindings). Having said that, if you’re looking for the best speed possible then sockets and TCP bindings are the way to go. But, they’re not the only game in town when it comes to duplex communication. The first time I heard about HTTP Polling Duplex (initially available in Silverlight 2) I wasn’t exactly sure how it was any better than standard polling used in AJAX applications. I read the Silverlight SDK, looked at various resources and generally found the following definition unhelpful as far as understanding the actual benefits that HTTP Polling Duplex provided: "The Silverlight client periodically polls the service on the network layer, and checks for any new messages that the service wants to send on the callback channel. The service queues all messages sent on the client callback channel and delivers them to the client when the client polls the service." Although the previous definition explained the overall process, it sounded as if standard polling was used. Fortunately, Microsoft’s Scott Guthrie provided me with a more clear definition several years back that explains the benefits provided by HTTP Polling Duplex quite well (used with his permission): "The [HTTP Polling Duplex] duplex support does use polling in the background to implement notifications – although the way it does it is different than manual polling. It initiates a network request, and then the request is effectively “put to sleep” waiting for the server to respond (it doesn’t come back immediately). The server then keeps the connection open but not active until it has something to send back (or the connection times out after 90 seconds – at which point the duplex client will connect again and wait). This way you are avoiding hitting the server repeatedly – but still get an immediate response when there is data to send." After hearing Scott’s definition the light bulb went on and it all made sense. A client makes a request to a server to check for changes, but instead of the request returning immediately, it parks itself on the server and waits for data. It’s kind of like waiting to pick up a pizza at the store. Instead of calling the store over and over to check the status, you sit in the store and wait until the pizza (the request data) is ready. Once it’s ready you take it back home (to the client). This technique provides a lot of efficiency gains over standard polling techniques even though it does use some polling of its own as a request is initially made from a client to a server. So how do you implement HTTP Polling Duplex in your Silverlight applications? Let’s take a look at the process by starting with the server. Creating an HTTP Polling Duplex WCF Service Creating a WCF service that exposes an HTTP Polling Duplex binding is straightforward as far as coding goes. Add some one way operations into an interface, create a client callback interface and you’re ready to go. The most challenging part comes into play when configuring the service to properly support the necessary binding and that’s more of a cut and paste operation once you know the configuration code to use. To create an HTTP Polling Duplex service you’ll need to expose server-side and client-side interfaces and reference the System.ServiceModel.PollingDuplex assembly (located at C:\Program Files (x86)\Microsoft SDKs\Silverlight\v4.0\Libraries\Server on my machine) in the server project. For the demo application I upgraded a basketball simulation service to support the latest polling duplex assemblies. The service simulates a simple basketball game using a Game class and pushes information about the game such as score, fouls, shots and more to the client as the game changes over time. Before jumping too far into the game push service, it’s important to discuss two interfaces used by the service to communicate in a bi-directional manner. The first is called IGameStreamService and defines the methods/operations that the client can call on the server (see Listing 1). The second is IGameStreamClient which defines the callback methods that a server can use to communicate with a client (see Listing 2).   [ServiceContract(Namespace = "Silverlight", CallbackContract = typeof(IGameStreamClient))] public interface IGameStreamService { [OperationContract(IsOneWay = true)] void GetTeamData(); } Listing 1. The IGameStreamService interface defines server operations that can be called on the server.   [ServiceContract] public interface IGameStreamClient { [OperationContract(IsOneWay = true)] void ReceiveTeamData(List<Team> teamData); [OperationContract(IsOneWay = true, AsyncPattern=true)] IAsyncResult BeginReceiveGameData(GameData gameData, AsyncCallback callback, object state); void EndReceiveGameData(IAsyncResult result); } Listing 2. The IGameStreamClient interfaces defines client operations that a server can call.   The IGameStreamService interface is decorated with the standard ServiceContract attribute but also contains a value for the CallbackContract property.  This property is used to define the interface that the client will expose (IGameStreamClient in this example) and use to receive data pushed from the service. Notice that each OperationContract attribute in both interfaces sets the IsOneWay property to true. This means that the operation can be called and passed data as appropriate, however, no data will be passed back. Instead, data will be pushed back to the client as it’s available.  Looking through the IGameStreamService interface you can see that the client can request team data whereas the IGameStreamClient interface allows team and game data to be received by the client. One interesting point about the IGameStreamClient interface is the inclusion of the AsyncPattern property on the BeginReceiveGameData operation. I initially created this operation as a standard one way operation and it worked most of the time. However, as I disconnected clients and reconnected new ones game data wasn’t being passed properly. After researching the problem more I realized that because the service could take up to 7 seconds to return game data, things were getting hung up. By setting the AsyncPattern property to true on the BeginReceivedGameData operation and providing a corresponding EndReceiveGameData operation I was able to get around this problem and get everything running properly. I’ll provide more details on the implementation of these two methods later in this post. Once the interfaces were created I moved on to the game service class. The first order of business was to create a class that implemented the IGameStreamService interface. Since the service can be used by multiple clients wanting game data I added the ServiceBehavior attribute to the class definition so that I could set its InstanceContextMode to InstanceContextMode.Single (in effect creating a Singleton service object). Listing 3 shows the game service class as well as its fields and constructor.   [ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Multiple, InstanceContextMode = InstanceContextMode.Single)] public class GameStreamService : IGameStreamService { object _Key = new object(); Game _Game = null; Timer _Timer = null; Random _Random = null; Dictionary<string, IGameStreamClient> _ClientCallbacks = new Dictionary<string, IGameStreamClient>(); static AsyncCallback _ReceiveGameDataCompleted = new AsyncCallback(ReceiveGameDataCompleted); public GameStreamService() { _Game = new Game(); _Timer = new Timer { Enabled = false, Interval = 2000, AutoReset = true }; _Timer.Elapsed += new ElapsedEventHandler(_Timer_Elapsed); _Timer.Start(); _Random = new Random(); }} Listing 3. The GameStreamService implements the IGameStreamService interface which defines a callback contract that allows the service class to push data back to the client. By implementing the IGameStreamService interface, GameStreamService must supply a GetTeamData() method which is responsible for supplying information about the teams that are playing as well as individual players.  GetTeamData() also acts as a client subscription method that tracks clients wanting to receive game data.  Listing 4 shows the GetTeamData() method. public void GetTeamData() { //Get client callback channel var context = OperationContext.Current; var sessionID = context.SessionId; var currClient = context.GetCallbackChannel<IGameStreamClient>(); context.Channel.Faulted += Disconnect; context.Channel.Closed += Disconnect; IGameStreamClient client; if (!_ClientCallbacks.TryGetValue(sessionID, out client)) { lock (_Key) { _ClientCallbacks[sessionID] = currClient; } } currClient.ReceiveTeamData(_Game.GetTeamData()); //Start timer which when fired sends updated score information to client if (!_Timer.Enabled) { _Timer.Enabled = true; } } Listing 4. The GetTeamData() method subscribes a given client to the game service and returns. The key the line of code in the GetTeamData() method is the call to GetCallbackChannel<IGameStreamClient>().  This method is responsible for accessing the calling client’s callback channel. The callback channel is defined by the IGameStreamClient interface shown earlier in Listing 2 and used by the server to communicate with the client. Before passing team data back to the client, GetTeamData() grabs the client’s session ID and checks if it already exists in the _ClientCallbacks dictionary object used to track clients wanting callbacks from the server. If the client doesn’t exist it adds it into the collection. It then pushes team data from the Game class back to the client by calling ReceiveTeamData().  Since the service simulates a basketball game, a timer is then started if it’s not already enabled which is then used to randomly send data to the client. When the timer fires, game data is pushed down to the client. Listing 5 shows the _Timer_Elapsed() method that is called when the timer fires as well as the SendGameData() method used to send data to the client. void _Timer_Elapsed(object sender, ElapsedEventArgs e) { int interval = _Random.Next(3000, 7000); lock (_Key) { _Timer.Interval = interval; _Timer.Enabled = false; } SendGameData(_Game.GetGameData()); } private void SendGameData(GameData gameData) { var cbs = _ClientCallbacks.Where(cb => ((IContextChannel)cb.Value).State == CommunicationState.Opened); for (int i = 0; i < cbs.Count(); i++) { var cb = cbs.ElementAt(i).Value; try { cb.BeginReceiveGameData(gameData, _ReceiveGameDataCompleted, cb); } catch (TimeoutException texp) { //Log timeout error } catch (CommunicationException cexp) { //Log communication error } } lock (_Key) _Timer.Enabled = true; } private static void ReceiveGameDataCompleted(IAsyncResult result) { try { ((IGameStreamClient)(result.AsyncState)).EndReceiveGameData(result); } catch (CommunicationException) { // empty } catch (TimeoutException) { // empty } } LIsting 5. _Timer_Elapsed is used to simulate time in a basketball game. When _Timer_Elapsed() fires the SendGameData() method is called which iterates through the clients wanting to be notified of changes. As each client is identified, their respective BeginReceiveGameData() method is called which ultimately pushes game data down to the client. Recall that this method was defined in the client callback interface named IGameStreamClient shown earlier in Listing 2. Notice that BeginReceiveGameData() accepts _ReceiveGameDataCompleted as its second parameter (an AsyncCallback delegate defined in the service class) and passes the client callback as the third parameter. The initial version of the sample application had a standard ReceiveGameData() method in the client callback interface. However, sometimes the client callbacks would work properly and sometimes they wouldn’t which was a little baffling at first glance. After some investigation I realized that I needed to implement an asynchronous pattern for client callbacks to work properly since 3 – 7 second delays are occurring as a result of the timer. Once I added the BeginReceiveGameData() and ReceiveGameDataCompleted() methods everything worked properly since each call was handled in an asynchronous manner. The final task that had to be completed to get the server working properly with HTTP Polling Duplex was adding configuration code into web.config. In the interest of brevity I won’t post all of the code here since the sample application includes everything you need. However, Listing 6 shows the key configuration code to handle creating a custom binding named pollingDuplexBinding and associate it with the service’s endpoint.   <bindings> <customBinding> <binding name="pollingDuplexBinding"> <binaryMessageEncoding /> <pollingDuplex maxPendingSessions="2147483647" maxPendingMessagesPerSession="2147483647" inactivityTimeout="02:00:00" serverPollTimeout="00:05:00"/> <httpTransport /> </binding> </customBinding> </bindings> <services> <service name="GameService.GameStreamService" behaviorConfiguration="GameStreamServiceBehavior"> <endpoint address="" binding="customBinding" bindingConfiguration="pollingDuplexBinding" contract="GameService.IGameStreamService"/> <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" /> </service> </services>   Listing 6. Configuring an HTTP Polling Duplex binding in web.config and associating an endpoint with it. Calling the Service and Receiving “Pushed” Data Calling the service and handling data that is pushed from the server is a simple and straightforward process in Silverlight. Since the service is configured with a MEX endpoint and exposes a WSDL file, you can right-click on the Silverlight project and select the standard Add Service Reference item. After the web service proxy is created you may notice that the ServiceReferences.ClientConfig file only contains an empty configuration element instead of the normal configuration elements created when creating a standard WCF proxy. You can certainly update the file if you want to read from it at runtime but for the sample application I fed the service URI directly to the service proxy as shown next: var address = new EndpointAddress("http://localhost.:5661/GameStreamService.svc"); var binding = new PollingDuplexHttpBinding(); _Proxy = new GameStreamServiceClient(binding, address); _Proxy.ReceiveTeamDataReceived += _Proxy_ReceiveTeamDataReceived; _Proxy.ReceiveGameDataReceived += _Proxy_ReceiveGameDataReceived; _Proxy.GetTeamDataAsync(); This code creates the proxy and passes the endpoint address and binding to use to its constructor. It then wires the different receive events to callback methods and calls GetTeamDataAsync().  Calling GetTeamDataAsync() causes the server to store the client in the server-side dictionary collection mentioned earlier so that it can receive data that is pushed.  As the server-side timer fires and game data is pushed to the client, the user interface is updated as shown in Listing 7. Listing 8 shows the _Proxy_ReceiveGameDataReceived() method responsible for handling the data and calling UpdateGameData() to process it.   Listing 7. The Silverlight interface. Game data is pushed from the server to the client using HTTP Polling Duplex. void _Proxy_ReceiveGameDataReceived(object sender, ReceiveGameDataReceivedEventArgs e) { UpdateGameData(e.gameData); } private void UpdateGameData(GameData gameData) { //Update Score this.tbTeam1Score.Text = gameData.Team1Score.ToString(); this.tbTeam2Score.Text = gameData.Team2Score.ToString(); //Update ball visibility if (gameData.Action != ActionsEnum.Foul) { if (tbTeam1.Text == gameData.TeamOnOffense) { AnimateBall(this.BB1, this.BB2); } else //Team 2 { AnimateBall(this.BB2, this.BB1); } } if (this.lbActions.Items.Count > 9) this.lbActions.Items.Clear(); this.lbActions.Items.Add(gameData.LastAction); if (this.lbActions.Visibility == Visibility.Collapsed) this.lbActions.Visibility = Visibility.Visible; } private void AnimateBall(Image onBall, Image offBall) { this.FadeIn.Stop(); Storyboard.SetTarget(this.FadeInAnimation, onBall); Storyboard.SetTarget(this.FadeOutAnimation, offBall); this.FadeIn.Begin(); } Listing 8. As the server pushes game data, the client’s _Proxy_ReceiveGameDataReceived() method is called to process the data. In a real-life application I’d go with a ViewModel class to handle retrieving team data, setup data bindings and handle data that is pushed from the server. However, for the sample application I wanted to focus on HTTP Polling Duplex and keep things as simple as possible.   Summary Silverlight supports three options when duplex communication is required in an application including TCP bindins, sockets and HTTP Polling Duplex. In this post you’ve seen how HTTP Polling Duplex interfaces can be created and implemented on the server as well as how they can be consumed by a Silverlight client. HTTP Polling Duplex provides a nice way to “push” data from a server while still allowing the data to flow over port 80 or another port of your choice.   Sample Application Download

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  • Sending Parameters with the BizTalk HTTP Adapter

    - by Christopher House
    I've never had occaison to use the BizTalk HTTP adapter since I've always needed SOAP rather than just POX (plain old XML).  Yesterday we decided that we're going to expose some data via a Java servlet that will accept an HTTP post and respond with POX.  I knew BizTalk had an HTTP adapter but I had no idea what it's capabilities were. After a quick read through the BizTalk docs, it was apparent that the HTTP send adapter does in fact do posts.  The concern I had though was how we were going to supply parameters to the servlet.  The examples I had seen using the HTTP adapter all involved posting an XML message to some HTTP location.  Our Java guy, however didn't want to take that approach.  He wanted us to provide a query string via post, much like you'd expect to see on an HTTP get.  I decided to put together a little test scenario and see what I could come up with.  We didn't have a test servlet I could go against and my Java experience is virtually nill, so I decided to put together an ASP.Net project to act as the servlet.  It didn't need to be fancy, just one HttpHandler that accepts a post, reads a parameter and returns XML.  With the HttpHandler done, I put together a simple orchestration to send a message to the handler.  I started by having the orch send a message of type System.String to see what it would look like when the handler received it. I set a breakpoint in my handler and kicked off the orchestration.  Below is what I saw: As I suspected, because of BizTalk's XML serialization, System.String was not going to work.  I thought back to my BizTalk 2004 days and I project I worked on that required sending HTML formatted emails via the SMTP adapter.  To acomplish that, I had used a .Net class with a custom serialization formatter that I got from a Microsoft sample.  The code for the class, RawString can be found here. I created a new class library with the RawString class as well as a static factory class, referenced that in my orchestration project and changed my message type from System.String to RawString.  Below is what the code in my message construction looks like: After deploying the updated orchestration, I fired it off again and checked the breakpoint in my HttpHandler.  This is what I saw: And there you have it.  The RawString message type allowed me to pass a query string in the HTTP post without wrapping it in XML.

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  • 2D Barcode Addendum

    - by Tim Dexter
    Having finally got my external drive back(long story) today from Oklahoma (thank you so much Sammy) Im back with a full compliment of Oracle and blogging tools at my disposal. I have missed JDeveloper this past week, which I have found, I immensely prefer over Eclipse (let the flaming commence :0) I use Zoundry Raven for writing articles and its not installed locally but on my external drove, so I have been soldiering on with the blog server's pain in the backside UI for writing. Now I have my favority editor back and things are calming down workwise, I will start to get the Excel template posts out. Today thou, a note about 2D barcode support or more specifically any barcode that needs some data manipulation before the barcode font is applied. I wrote about these fonts a long time back and laid out the java class you would need to write if you had an algorithm from the font manufacturer to use. I missed out a valuable point and James at Luminex fell into the trap. He was wanting to use the datamatrix font from IDAutomation but and had built the java class to be called from the RTF template but it was not encoding or at least did not appear to be. New debugging feature to the rescue. Kan over at the bipconsultng blog documented the feature a while back. Just adding <?xdo-debug-level:'STATEMENT'?> to my test template generated all the debug files in my c:\temp directory. No messing with files, just a simple command ... at last! Kan has documented the feature here. With the log in hand I spotted a java error stack referencing a missing code128a method, huh? Looking at James' class he had the following snippet: ENCODERS.put("code128a",mUtility.getClass().getMethod("code128a",clazz)); ENCODERS.put("code128b",mUtility.getClass().getMethod("code128b", clazz)); ENCODERS.put("code128c",mUtility.getClass().getMethod("code128c", clazz)); ENCODERS.put("pdf417",mUtility.getClass().getMethod("pdf417", clazz)); ENCODERS.put("datamatrix",mUtility.getClass().getMethod("datamatrix", clazz)); His class did not include the other code128 and pdf147 methods and BIP was expecting them. An easy fix, just comment them out, rebuild and deploy and the encoding started working. If you are hitting similar problems, check that class and ensure all of the referenced methods are available, if not, delete or get commenting. James now has purdy labels popping out that his hard ware can read, sweet!

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  • Control Sysinternals Suite & NirSoft Utilities with a Single Interface

    - by Asian Angel
    Sysinternals and NirSoft both provide helpful utilities for your Windows system but may not be very convenient to access. Using the Windows System Control Center you can easily access everything through a single UI front end. Setup The first thing to do is set up three new folders in Program Files (or Program Files (x86) if you are using a 64bit system) with the following names (the first two need to exactly match what is shown here): Sysinternals Suite NirSoft Utilities (create this folder only if you have any of these apps downloaded) Windows System Control Center (or WSCC depending on your preferences) Unzip the contents of the Sysinternals Suite into its’ folder. Then unzip any individual NirSoft Utilities programs that you have downloaded into the NirSoft folder. All that is left to do is to unzip the WSCC software into its’ folder and create a shortcut. WSCC in Action When you start WSCC up for the first time you will see the following message with a brief explanation about the software. Next the options window will appear providing you an opportunity to look around and make any desired changes. WSCC can access utilities for both suites using a live connection if needed (utilities accessed live are not downloaded). Note: This occurs on the first run only. This is the main WSCC window…you can choose the utility that you want to use by sorting through an all items list or based on category. Note: WSCC may occasionally experience a problem downloading a particular utility if using the live service. We conducted a quick test by accessing two Sysinternals apps. First PsInfo… Followed by DiskView. Both opened quickly and were ready to go. There were no NirSoft Utilities installed on our test system in order to provide a live access example. Within moments WSCC accessed the CurrProcess utility and had it running on our system. Our recommendation is to download your favorite utilities from both suites (in order to always have easy access to them). Conclusion WSCC provides an easy way to access all of the apps in the Sysinternals Suite and NirSoft Utilities in one place. Note: A PortableApps version is also available. Links Download Windows System Control Center (WSCC) Download Windows Sysinternals Suite Download individual NirSoft Utilities programs Similar Articles Productive Geek Tips How To Get Detailed Information About Your PCAccess and Launch Windows Utilities the Easy WayWhat is svchost.exe And Why Is It Running?How to Clean Up Your Messy Windows Context MenuRemove NVIDIA Control Panel from Desktop Right-Click Menu TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips CloudBerry Online Backup 1.5 for Windows Home Server Snagit 10 VMware Workstation 7 Acronis Online Backup Ultimate Boot CD can help when disaster strikes Windows Firewall with Advanced Security – How To Guides Sculptris 1.0, 3D Drawing app AceStock, a Tiny Desktop Quote Monitor Gmail Button Addon (Firefox) Hyperwords addon (Firefox)

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  • Looking into ASP.Net MVC 4.0 Mobile Development - part 2

    - by nikolaosk
    In this post I will be continuing my discussion on ASP.Net MVC 4.0 mobile development. You can have a look at my first post on the subject here . Make sure you read it and understand it well before you move one reading the remaining of this post. I will not be writing any code in this post. I will try to explain a few concepts related to the MVC 4.0 mobile functionality. In this post I will be looking into the Browser Overriding feature in ASP.Net MVC 4.0. By that I mean that we override the user agent for a given user session. This is very useful feature for people who visit a site through a device and they experience the mobile version of the site, but what they really want is the option to be able to switch to the desktop view. "Why they might want to do that?", you might wonder.Well first of all the users of our ASP.Net MVC 4.0 application will appreciate that they have the option to switch views while some others will think that they will enjoy more the contents of our website with the "desktop view" since the mobile device they view our site has a quite large display.  Obviously this is only one site. These are just different views that are rendered.To put it simply, browser overriding lets our application treat requests as if they were coming from a different browser rather than the one they are actually from. In order to do that programmatically we must have a look at the System.Web.WebPages namespace and the classes in it. Most specifically the class BrowserHelpers. Have a look at the picture below   In this class we see some extension methods for HttpContext class.These methods are called extensions-helpers methods and we use them to switch to one browser from another thus overriding the current/actual browser. These APIs have effect on layout,views and partial views and will not affect any other ASP.Net Request.Browser related functionality.The overridden browser is stored in a cookie. Let me explain what some of these methods do. SetOverriddenBrowser() -  let us set the user agent string to specific value GetOverriddenBrowser() -  let us get the overridden value ClearOverriddenBrowser() -  let us remove any overridden user agent for the current request   To recap, in our ASP.Net MVC 4.0 applications when our application is viewed in our mobile devices, we can have a link like "Desktop View" for all those who desperately want to see the site with in full desktop-browser version.We then can specify a browser type override. My controller class (snippet of code) that is responsible for handling the switching could be something like that. public class SwitchViewController : Controller{ public RedirectResult SwitchView(bool mobile, string returnUrl){if (Request.Browser.IsMobileDevice == mobile)HttpContext.ClearOverriddenBrowser();elseHttpContext.SetOverriddenBrowser(mobile ? BrowserOverride.Mobile : BrowserOverride.Desktop);return Redirect(returnUrl);}} Hope it helps!!!!

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  • Graphics module: Am I going the right way?

    - by Paul
    I'm trying to write the graphics module of my engine. That is, this part of the code only provides an interface through which to load images, fonts, etc and draw them on the screen. It is also a wrapper for the library I'm using (SDL in this case). Here are the interfaces for my Image, Font and GraphicsRenderer classes. Please tell me if I'm going the right way. Image class Image { public: Image(); Image(const Image& other); Image(const char* file); ~Image(); bool load(const char* file); void free(); bool isLoaded() const; Image& operator=(const Image& other); private: friend class GraphicsRenderer; void* data_; }; Font class Font { public: Font(); Font(const Font& other); Font(const char* file, int ptsize); ~Font(); void load(const char* file, int ptsize); void free(); bool isLoaded() const; Font& operator=(const Font& other); private: friend class GraphicsRenderer; void* data_; }; GrapphicsRenderer class GraphicsRenderer { public: static GraphicsRenderer* Instance(); void blitImage(const Image& img, int x, int y); void blitText(const char* string, const Font& font, int x, int y); void render(); protected: GraphicsRenderer(); GraphicsRenderer(const GraphicsRenderer& other); GraphicsRenderer& operator=(const GraphicsRenderer& other); ~GraphicsRenderer(); private: void* screen_; bool initialize(); void finalize(); };

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  • A Generic, IDisposable WCF Service Client

    - by Steve Wilkes
    WCF clients need to be cleaned up properly, but as they're usually auto-generated they don't implement IDisposable. I've been doing a fair bit of WCF work recently, so I wrote a generic WCF client wrapper which effectively gives me a disposable service client. The ServiceClientWrapper is constructed using a WebServiceConfig instance, which contains a Binding, an EndPointAddress, and whether the client should ignore SSL certificate errors - pretty useful during testing! The Binding can be created based on configuration data or entirely programmatically - that's not the client's concern. Here's the service client code: using System; using System.Net; using System.Net.Security; using System.ServiceModel; public class ServiceClientWrapper<TService, TChannel> : IDisposable     where TService : ClientBase<TChannel>     where TChannel : class {     private readonly WebServiceConfig _config;     private TService _serviceClient;     public ServiceClientWrapper(WebServiceConfig config)     {         this._config = config;     }     public TService CreateServiceClient()     {         this.DisposeExistingServiceClientIfRequired();         if (this._config.IgnoreSslErrors)         {             ServicePointManager.ServerCertificateValidationCallback =                 (obj, certificate, chain, errors) => true;         }         else         {             ServicePointManager.ServerCertificateValidationCallback =                 (obj, certificate, chain, errors) => errors == SslPolicyErrors.None;         }         this._serviceClient = (TService)Activator.CreateInstance(             typeof(TService),             this._config.Binding,             this._config.Endpoint);         if (this._config.ClientCertificate != null)         {             this._serviceClient.ClientCredentials.ClientCertificate.Certificate =                 this._config.ClientCertificate;         }         return this._serviceClient;     }     public void Dispose()     {         this.DisposeExistingServiceClientIfRequired();     }     private void DisposeExistingServiceClientIfRequired()     {         if (this._serviceClient != null)         {             try             {                 if (this._serviceClient.State == CommunicationState.Faulted)                 {                     this._serviceClient.Abort();                 }                 else                 {                     this._serviceClient.Close();                 }             }             catch             {                 this._serviceClient.Abort();             }             this._serviceClient = null;         }     } } A client for a particular service can then be created something like this: public class ManagementServiceClientWrapper :     ServiceClientWrapper<ManagementServiceClient, IManagementService> {     public ManagementServiceClientWrapper(WebServiceConfig config)         : base(config)     {     } } ...where ManagementServiceClient is the auto-generated client class, and the IManagementService is the auto-generated WCF channel class - and used like this: using(var serviceClientWrapper = new ManagementServiceClientWrapper(config)) {     serviceClientWrapper.CreateServiceClient().CallService(); } The underlying WCF client created by the CreateServiceClient() will be disposed after the using, and hey presto - a disposable WCF service client.

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  • SQL SERVER – Weekly Series – Memory Lane – #050

    - by Pinal Dave
    Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Executing Remote Stored Procedure – Calling Stored Procedure on Linked Server In this example we see two different methods of how to call Stored Procedures remotely.  Connection Property of SQL Server Management Studio SSMS A very simple example of the how to build connection properties for SQL Server with the help of SSMS. Sample Example of RANKING Functions – ROW_NUMBER, RANK, DENSE_RANK, NTILE SQL Server has a total of 4 ranking functions. Ranking functions return a ranking value for each row in a partition. All the ranking functions are non-deterministic. T-SQL Script to Add Clustered Primary Key Jr. DBA asked me three times in a day, how to create Clustered Primary Key. I gave him following sample example. That was the last time he asked “How to create Clustered Primary Key to table?” 2008 2008 – TRIM() Function – User Defined Function SQL Server does not have functions which can trim leading or trailing spaces of any string at the same time. SQL does have LTRIM() and RTRIM() which can trim leading and trailing spaces respectively. SQL Server 2008 also does not have TRIM() function. User can easily use LTRIM() and RTRIM() together and simulate TRIM() functionality. http://www.youtube.com/watch?v=1-hhApy6MHM 2009 Earlier I have written two different articles on the subject Remove Bookmark Lookup. This article is as part 3 of original article. Please read the first two articles here before continuing reading this article. Query Optimization – Remove Bookmark Lookup – Remove RID Lookup – Remove Key Lookup Query Optimization – Remove Bookmark Lookup – Remove RID Lookup – Remove Key Lookup – Part 2 Query Optimization – Remove Bookmark Lookup – Remove RID Lookup – Remove Key Lookup – Part 3 Interesting Observation – Query Hint – FORCE ORDER SQL Server never stops to amaze me. As regular readers of this blog already know that besides conducting corporate training, I work on large-scale projects on query optimizations and server tuning projects. In one of the recent projects, I have noticed that a Junior Database Developer used the query hint Force Order; when I asked for details, I found out that the basic concept was not properly understood by him. Queries Waiting for Memory Allocation to Execute In one of the recent projects, I was asked to create a report of queries that are waiting for memory allocation. The reason was that we were doubtful regarding whether the memory was sufficient for the application. The following query can be useful in similar cases. Queries that do not have to wait on a memory grant will not appear in the result set of following query. 2010 Quickest Way to Identify Blocking Query and Resolution – Dirty Solution As the title suggests, this is quite a dirty solution; it’s not as elegant as you expect. However, it works totally fine. Simple Explanation of Data Type Precedence While I was working on creating a question for SQL SERVER – SQL Quiz – The View, The Table and The Clustered Index Confusion, I had actually created yet another question along with this question. However, I felt that the one which is posted on the SQL Quiz is much better than this one because what makes that more challenging question is that it has a multiple answer. Encrypted Stored Procedure and Activity Monitor I recently had received questionable if any stored procedure is encrypted can we see its definition in Activity Monitor.Answer is - No. Let us do a quick test. Let us create following Stored Procedure and then launch the Activity Monitor and check the text. Indexed View always Use Index on Table A single table can have maximum 249 non clustered indexes and 1 clustered index. In SQL Server 2008, a single table can have maximum 999 non clustered indexes and 1 clustered index. It is widely believed that a table can have only 1 clustered index, and this belief is true. I have some questions for all of you. Let us assume that I am creating view from the table itself and then create a clustered index on it. In my view, I am selecting the complete table itself. 2011 Detecting Database Case Sensitive Property using fn_helpcollations() I received a question on how to determine the case sensitivity of the database. The quick answer to this is to identify the collation of the database and check the properties of the collation. I have previously written how one can identify database collation. Once you have figured out the collation of the database, you can put that in the WHERE condition of the following T-SQL and then check the case sensitivity from the description. Server Side Paging in SQL Server CE (Compact Edition) SQL Server Denali is coming up with new T-SQL of Paging. I have written about the same earlier.SQL SERVER – Server Side Paging in SQL Server Denali – A Better Alternative,  SQL SERVER – Server Side Paging in SQL Server Denali Performance Comparison, SQL SERVER – Server Side Paging in SQL Server Denali – Part2 What is very interesting is that SQL Server CE 4.0 have the same feature introduced. Here is the quick example of the same. To run the script in the example, you will have to do installWebmatrix 4.0 and download sample database. Once done you can run following script. Why I am Going to Attend PASS Summit Unite 2011 The four-day event will be marked by a lot of learning, sharing, and networking, which will help me increase both my knowledge and contacts. Every year, PASS Summit provides me a golden opportunity to build my network as well as to identify and meet potential customers or employees. 2012 Manage Help Settings – CTRL + ALT + F1 This is very interesting read as my daughter once accidently came across a screen in SQL Server Management Studio. It took me 2-3 minutes to figure out how she has created the same screen. Recover the Accidentally Renamed Table “I accidentally renamed table in my SSMS. I was scrolling very fast and I made mistakes. It was either because I double clicked or clicked on F2 (shortcut key for renaming). However, I have made the mistake and now I have no idea how to fix this. If you have renamed the table, I think you pretty much is out of luck. Here are few things which you can do which can give you an idea about what your table name can be if you are lucky. Identify Numbers of Non Clustered Index on Tables for Entire Database Here is the script which will give you numbers of non clustered indexes on any table in entire database. Identify Most Resource Intensive Queries – SQL in Sixty Seconds #029 – Video Here is the complete complete script which I have used in the SQL in Sixty Seconds Video. Thanks Harsh for important Tip in the comment. http://www.youtube.com/watch?v=3kDHC_Tjrns Advanced Data Quality Services with Melissa Data – Azure Data Market For the purposes of the review, I used a database I had in an Excel spreadsheet with name and address information. Upon a cursory inspection, there are miscellaneous problems with these records; some addresses are missing ZIP codes, others missing a city, and some records are slightly misspelled or have unparsed suites. With DQS, I can easily add a knowledge base to help standardize my values, such as for state abbreviations. But how do I know that my address is correct? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Extending the ADF Controller exception handler

    - by frank.nimphius
    The Oracle ADF controller provides a declarative option for developers to define a view activity, method activity or router activity to handle exceptions in bounded or unbounded task flows. Exception handling however is for exceptions only and not handling all types of Throwable. Furthermore, exceptions that occur during the JSF RENDER RESPONSE phase are not looked at either as it is considered too late in the cycle. For developers to try themselves to handle unhandled exceptions in ADF Controller, it is possible to extend the default exception handling, while still leveraging the declarative configuration. To add your own exception handler: · Create a Java class that extends ExceptionHandler · Create a textfile with the name “oracle.adf.view.rich.context.Exceptionhandler” (without the quotes) and store it in .adf\META-INF\services (you need to create the “services” folder) · In the file, add the absolute name of your custom exception handler class (package name and class name without the “.class” extension) For any exception you don't handle in your custom exception handler, just re-throw it for the default handler to give it a try … import oracle.adf.view.rich.context.ExceptionHandler; public class MyCustomExceptionHandler extends ExceptionHandler { public MyCustomExceptionHandler() {      super(); } public void handleException(FacesContext facesContext,                              Throwable throwable, PhaseId phaseId)                              throws Throwable {    String error_message;    error_message = throwable.getMessage();    //check error message and handle it if you can    if( … ){          //handle exception        …    }    else{       //delegate to the default ADFc exception handler        throw throwable;}    } } Note however, that it is recommended to first try and handle exceptions with the ADF Controller default exception handling mechanism. In the past, I've seen attempts on OTN to handle regular application use cases with custom exception handlers for where there was no need to override the exception handler. So don't go for this solution to quickly and always think of alternative solutions. Sometimes a try-catch-final block does it better than sophisticated web exception handling.

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  • Hierarchy flattening of interfaces in WCF

    - by nmarun
    Alright, so say I have my service contract interface as below: 1: [ServiceContract] 2: public interface ILearnWcfService 3: { 4: [OperationContract(Name = "AddInt")] 5: int Add(int arg1, int arg2); 6: } Say I decided to add another interface with a similar add “feature”. 1: [ServiceContract] 2: public interface ILearnWcfServiceExtend : ILearnWcfService 3: { 4: [OperationContract(Name = "AddDouble")] 5: double Add(double arg1, double arg2); 6: } My class implementing the ILearnWcfServiceExtend ends up as: 1: public class LearnWcfService : ILearnWcfServiceExtend 2: { 3: public int Add(int arg1, int arg2) 4: { 5: return arg1 + arg2; 6: } 7:  8: public double Add(double arg1, double arg2) 9: { 10: return arg1 + arg2; 11: } 12: } Now when I consume this service and look at the proxy that gets generated, here’s what I see: 1: public interface ILearnWcfServiceExtend 2: { 3: [System.ServiceModel.OperationContractAttribute(Action="http://tempuri.org/ILearnWcfService/AddInt", ReplyAction="http://tempuri.org/ILearnWcfService/AddIntResponse")] 4: int AddInt(int arg1, int arg2); 5: 6: [System.ServiceModel.OperationContractAttribute(Action="http://tempuri.org/ILearnWcfServiceExtend/AddDouble", ReplyAction="http://tempuri.org/ILearnWcfServiceExtend/AddDoubleResponse")] 7: double AddDouble(double arg1, double arg2); 8: } Only the ILearnWcfServiceExtend gets ‘listed’ in the proxy class and not the (base interface) ILearnWcfService interface. But then to uniquely identify the operations that the service exposes, the Action and ReplyAction properties are set. So in the above example, the AddInt operation has the Action property set to ‘http://tempuri.org/ILearnWcfService/AddInt’ and the AddDouble operation has the Action property of ‘http://tempuri.org/ILearnWcfServiceExtend/AddDouble’. Similarly the ReplyAction properties are set corresponding to the namespace that they’re declared in. The ‘http://tempuri.org’ is chosen as the default namespace, since the Namespace property on the ServiceContract is not defined. The other thing is the service contract itself – the Add() method. You’ll see that in both interfaces, the method names are the same. As you might know, this is not allowed in WSDL-based environments, even though the arguments are of different types. This is allowed only if the Name attribute of the ServiceContract is set (as done above). This causes a change in the name of the service contract itself in the proxy class. See that their names are changed to AddInt / AddDouble respectively. Lesson learned: The interface hierarchy gets ‘flattened’ when the WCF service proxy class gets generated.

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  • What are the alternatives to "overriding a method" when using composition instead of inheritance?

    - by Sebastien Diot
    If we should favor composition over inheritance, the data part of it is clear, at least for me. What I don't have a clear solution to is how overwriting methods, or simply implementing them if they are defined in a pure virtual form, should be implemented. An obvious way is to wrap the instance representing the base-class into the instance representing the sub-class. But the major downsides of this are that if you have say 10 methods, and you want to override a single one, you still have to delegate every other methods anyway. And if there were several layers of inheritance, you have now several layers of wrapping, which becomes less and less efficient. Also, this only solve the problem of the object "client"; when another object calls the top wrapper, things happen like in inheritance. But when a method of the deepest instance, the base class, calls it's own methods that have been wrapped and modified, the wrapping has no effect: the call is performed by it's own method, instead of by the highest wrapper. One extreme alternative that would solve those problems would be to have one instance per method. You only wrap methods that you want to overwrite, so there is no pointless delegation. But now you end up with an incredible amount of classes and object instance, which will have a negative effect on memory usage, and this will require a lot more coding too. So, are there alternatives (preferably alternatives that can be used in Java), that: Do not result in many levels of pointless delegation without any changes. Make sure that not only the client of an object, but also all the code of the object itself, is aware of which implementation of method should be called. Does not result in an explosion of classes and instances. Ideally puts the extra memory overhead that is required at the "class"/"particular composition" level (static if you will), rather than having every object pay the memory overhead of composition. My feeling tells me that the instance representing the base class should be at the "top" of the stack/layers so it receives calls directly, and can process them directly too if they are not overwritten. But I don't know how to do it that way.

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  • ASP.NET MVC 3 Hosting :: Deploying ASP.NET MVC 3 web application to server where ASP.NET MVC 3 is not installed

    - by mbridge
    You can built sample application on ASP.NET MVC 3 for deploying it to your hosting first. To try it out first put it to web server where ASP.NET MVC 3 installed. In this posting I will tell you what files you need and where you can find them. Here are the files you need to upload to get application running on server where ASP.NET MVC 3 is not installed. Also you can deploying ASP.NET MVC 3 web application to server where ASP.NET MVC 3 is not installed like this example: you can change reference to System.Web.Helpers.dll to be the local one so it is copied to bin folder of your application. First file in this list is my web application dll and you don’t need it to get ASP.NET MVC 3 running. All other files are located at the following folder: C:\Program Files\Microsoft ASP.NET\ASP.NET Web Pages\v1.0\Assemblies\ If there are more files needed in some other scenarios then please leave me a comment here. And… don’t forget to convert the folder in IIS to application. While developing an application locally, this isn’t a problem. But when you are ready to deploy your application to a hosting provider, this might well be a problem if the hoster does not have the ASP.NET MVC assemblies installed in the GAC. Fortunately, ASP.NET MVC is still bin-deployable. If your hosting provider has ASP.NET 3.5 SP1 installed, then you’ll only need to include the MVC DLL. If your hosting provider is still on ASP.NET 3.5, then you’ll need to deploy all three. It turns out that it’s really easy to do so. Also, ASP.NET MVC runs in Medium Trust, so it should work with most hosting providers’ Medium Trust policies. It’s always possible that a hosting provider customizes their Medium Trust policy to be draconian. Deployment is easy when you know what to copy in archive for publishing your web site on ASP.NET MVC 3 or later versions. What I like to do is use the Publish feature of Visual Studio to publish to a local directory and then upload the files to my hosting provider. If your hosting provider supports FTP, you can often skip this intermediate step and publish directly to the FTP site. The first thing I do in preparation is to go to my MVC web application project and expand the References node in the project tree. Select the aforementioned three assemblies and in the Properties dialog, set Copy Local to True. Now just right click on your application and select Publish. This brings up the following Publish wizard Notice that in this example, I selected a local directory. When I hit Publish, all the files needed to deploy my app are available in the directory I chose, including the assemblies that were in the GAC. Another ASP.NET MVC 3 article: - New Features in ASP.NET MVC 3 - ASP.NET MVC 3 First Look

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  • C#/.NET Little Wonders: The Generic Func Delegates

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. Back in one of my three original “Little Wonders” Trilogy of posts, I had listed generic delegates as one of the Little Wonders of .NET.  Later, someone posted a comment saying said that they would love more detail on the generic delegates and their uses, since my original entry just scratched the surface of them. Last week, I began our look at some of the handy generic delegates built into .NET with a description of delegates in general, and the Action family of delegates.  For this week, I’ll launch into a look at the Func family of generic delegates and how they can be used to support generic, reusable algorithms and classes. Quick Delegate Recap Delegates are similar to function pointers in C++ in that they allow you to store a reference to a method.  They can store references to either static or instance methods, and can actually be used to chain several methods together in one delegate. Delegates are very type-safe and can be satisfied with any standard method, anonymous method, or a lambda expression.  They can also be null as well (refers to no method), so care should be taken to make sure that the delegate is not null before you invoke it. Delegates are defined using the keyword delegate, where the delegate’s type name is placed where you would typically place the method name: 1: // This delegate matches any method that takes string, returns nothing 2: public delegate void Log(string message); This delegate defines a delegate type named Log that can be used to store references to any method(s) that satisfies its signature (whether instance, static, lambda expression, etc.). Delegate instances then can be assigned zero (null) or more methods using the operator = which replaces the existing delegate chain, or by using the operator += which adds a method to the end of a delegate chain: 1: // creates a delegate instance named currentLogger defaulted to Console.WriteLine (static method) 2: Log currentLogger = Console.Out.WriteLine; 3:  4: // invokes the delegate, which writes to the console out 5: currentLogger("Hi Standard Out!"); 6:  7: // append a delegate to Console.Error.WriteLine to go to std error 8: currentLogger += Console.Error.WriteLine; 9:  10: // invokes the delegate chain and writes message to std out and std err 11: currentLogger("Hi Standard Out and Error!"); While delegates give us a lot of power, it can be cumbersome to re-create fairly standard delegate definitions repeatedly, for this purpose the generic delegates were introduced in various stages in .NET.  These support various method types with particular signatures. Note: a caveat with generic delegates is that while they can support multiple parameters, they do not match methods that contains ref or out parameters. If you want to a delegate to represent methods that takes ref or out parameters, you will need to create a custom delegate. We’ve got the Func… delegates Just like it’s cousin, the Action delegate family, the Func delegate family gives us a lot of power to use generic delegates to make classes and algorithms more generic.  Using them keeps us from having to define a new delegate type when need to make a class or algorithm generic. Remember that the point of the Action delegate family was to be able to perform an “action” on an item, with no return results.  Thus Action delegates can be used to represent most methods that take 0 to 16 arguments but return void.  You can assign a method The Func delegate family was introduced in .NET 3.5 with the advent of LINQ, and gives us the power to define a function that can be called on 0 to 16 arguments and returns a result.  Thus, the main difference between Action and Func, from a delegate perspective, is that Actions return nothing, but Funcs return a result. The Func family of delegates have signatures as follows: Func<TResult> – matches a method that takes no arguments, and returns value of type TResult. Func<T, TResult> – matches a method that takes an argument of type T, and returns value of type TResult. Func<T1, T2, TResult> – matches a method that takes arguments of type T1 and T2, and returns value of type TResult. Func<T1, T2, …, TResult> – and so on up to 16 arguments, and returns value of type TResult. These are handy because they quickly allow you to be able to specify that a method or class you design will perform a function to produce a result as long as the method you specify meets the signature. For example, let’s say you were designing a generic aggregator, and you wanted to allow the user to define how the values will be aggregated into the result (i.e. Sum, Min, Max, etc…).  To do this, we would ask the user of our class to pass in a method that would take the current total, the next value, and produce a new total.  A class like this could look like: 1: public sealed class Aggregator<TValue, TResult> 2: { 3: // holds method that takes previous result, combines with next value, creates new result 4: private Func<TResult, TValue, TResult> _aggregationMethod; 5:  6: // gets or sets the current result of aggregation 7: public TResult Result { get; private set; } 8:  9: // construct the aggregator given the method to use to aggregate values 10: public Aggregator(Func<TResult, TValue, TResult> aggregationMethod = null) 11: { 12: if (aggregationMethod == null) throw new ArgumentNullException("aggregationMethod"); 13:  14: _aggregationMethod = aggregationMethod; 15: } 16:  17: // method to add next value 18: public void Aggregate(TValue nextValue) 19: { 20: // performs the aggregation method function on the current result and next and sets to current result 21: Result = _aggregationMethod(Result, nextValue); 22: } 23: } Of course, LINQ already has an Aggregate extension method, but that works on a sequence of IEnumerable<T>, whereas this is designed to work more with aggregating single results over time (such as keeping track of a max response time for a service). We could then use this generic aggregator to find the sum of a series of values over time, or the max of a series of values over time (among other things): 1: // creates an aggregator that adds the next to the total to sum the values 2: var sumAggregator = new Aggregator<int, int>((total, next) => total + next); 3:  4: // creates an aggregator (using static method) that returns the max of previous result and next 5: var maxAggregator = new Aggregator<int, int>(Math.Max); So, if we were timing the response time of a web method every time it was called, we could pass that response time to both of these aggregators to get an idea of the total time spent in that web method, and the max time spent in any one call to the web method: 1: // total will be 13 and max 13 2: int responseTime = 13; 3: sumAggregator.Aggregate(responseTime); 4: maxAggregator.Aggregate(responseTime); 5:  6: // total will be 20 and max still 13 7: responseTime = 7; 8: sumAggregator.Aggregate(responseTime); 9: maxAggregator.Aggregate(responseTime); 10:  11: // total will be 40 and max now 20 12: responseTime = 20; 13: sumAggregator.Aggregate(responseTime); 14: maxAggregator.Aggregate(responseTime); The Func delegate family is useful for making generic algorithms and classes, and in particular allows the caller of the method or user of the class to specify a function to be performed in order to generate a result. What is the result of a Func delegate chain? If you remember, we said earlier that you can assign multiple methods to a delegate by using the += operator to chain them.  So how does this affect delegates such as Func that return a value, when applied to something like the code below? 1: Func<int, int, int> combo = null; 2:  3: // What if we wanted to aggregate the sum and max together? 4: combo += (total, next) => total + next; 5: combo += Math.Max; 6:  7: // what is the result? 8: var comboAggregator = new Aggregator<int, int>(combo); Well, in .NET if you chain multiple methods in a delegate, they will all get invoked, but the result of the delegate is the result of the last method invoked in the chain.  Thus, this aggregator would always result in the Math.Max() result.  The other chained method (the sum) gets executed first, but it’s result is thrown away: 1: // result is 13 2: int responseTime = 13; 3: comboAggregator.Aggregate(responseTime); 4:  5: // result is still 13 6: responseTime = 7; 7: comboAggregator.Aggregate(responseTime); 8:  9: // result is now 20 10: responseTime = 20; 11: comboAggregator.Aggregate(responseTime); So remember, you can chain multiple Func (or other delegates that return values) together, but if you do so you will only get the last executed result. Func delegates and co-variance/contra-variance in .NET 4.0 Just like the Action delegate, as of .NET 4.0, the Func delegate family is contra-variant on its arguments.  In addition, it is co-variant on its return type.  To support this, in .NET 4.0 the signatures of the Func delegates changed to: Func<out TResult> – matches a method that takes no arguments, and returns value of type TResult (or a more derived type). Func<in T, out TResult> – matches a method that takes an argument of type T (or a less derived type), and returns value of type TResult(or a more derived type). Func<in T1, in T2, out TResult> – matches a method that takes arguments of type T1 and T2 (or less derived types), and returns value of type TResult (or a more derived type). Func<in T1, in T2, …, out TResult> – and so on up to 16 arguments, and returns value of type TResult (or a more derived type). Notice the addition of the in and out keywords before each of the generic type placeholders.  As we saw last week, the in keyword is used to specify that a generic type can be contra-variant -- it can match the given type or a type that is less derived.  However, the out keyword, is used to specify that a generic type can be co-variant -- it can match the given type or a type that is more derived. On contra-variance, if you are saying you need an function that will accept a string, you can just as easily give it an function that accepts an object.  In other words, if you say “give me an function that will process dogs”, I could pass you a method that will process any animal, because all dogs are animals.  On the co-variance side, if you are saying you need a function that returns an object, you can just as easily pass it a function that returns a string because any string returned from the given method can be accepted by a delegate expecting an object result, since string is more derived.  Once again, in other words, if you say “give me a method that creates an animal”, I can pass you a method that will create a dog, because all dogs are animals. It really all makes sense, you can pass a more specific thing to a less specific parameter, and you can return a more specific thing as a less specific result.  In other words, pay attention to the direction the item travels (parameters go in, results come out).  Keeping that in mind, you can always pass more specific things in and return more specific things out. For example, in the code below, we have a method that takes a Func<object> to generate an object, but we can pass it a Func<string> because the return type of object can obviously accept a return value of string as well: 1: // since Func<object> is co-variant, this will access Func<string>, etc... 2: public static string Sequence(int count, Func<object> generator) 3: { 4: var builder = new StringBuilder(); 5:  6: for (int i=0; i<count; i++) 7: { 8: object value = generator(); 9: builder.Append(value); 10: } 11:  12: return builder.ToString(); 13: } Even though the method above takes a Func<object>, we can pass a Func<string> because the TResult type placeholder is co-variant and accepts types that are more derived as well: 1: // delegate that's typed to return string. 2: Func<string> stringGenerator = () => DateTime.Now.ToString(); 3:  4: // This will work in .NET 4.0, but not in previous versions 5: Sequence(100, stringGenerator); Previous versions of .NET implemented some forms of co-variance and contra-variance before, but .NET 4.0 goes one step further and allows you to pass or assign an Func<A, BResult> to a Func<Y, ZResult> as long as A is less derived (or same) as Y, and BResult is more derived (or same) as ZResult. Sidebar: The Func and the Predicate A method that takes one argument and returns a bool is generally thought of as a predicate.  Predicates are used to examine an item and determine whether that item satisfies a particular condition.  Predicates are typically unary, but you may also have binary and other predicates as well. Predicates are often used to filter results, such as in the LINQ Where() extension method: 1: var numbers = new[] { 1, 2, 4, 13, 8, 10, 27 }; 2:  3: // call Where() using a predicate which determines if the number is even 4: var evens = numbers.Where(num => num % 2 == 0); As of .NET 3.5, predicates are typically represented as Func<T, bool> where T is the type of the item to examine.  Previous to .NET 3.5, there was a Predicate<T> type that tended to be used (which we’ll discuss next week) and is still supported, but most developers recommend using Func<T, bool> now, as it prevents confusion with overloads that accept unary predicates and binary predicates, etc.: 1: // this seems more confusing as an overload set, because of Predicate vs Func 2: public static SomeMethod(Predicate<int> unaryPredicate) { } 3: public static SomeMethod(Func<int, int, bool> binaryPredicate) { } 4:  5: // this seems more consistent as an overload set, since just uses Func 6: public static SomeMethod(Func<int, bool> unaryPredicate) { } 7: public static SomeMethod(Func<int, int, bool> binaryPredicate) { } Also, even though Predicate<T> and Func<T, bool> match the same signatures, they are separate types!  Thus you cannot assign a Predicate<T> instance to a Func<T, bool> instance and vice versa: 1: // the same method, lambda expression, etc can be assigned to both 2: Predicate<int> isEven = i => (i % 2) == 0; 3: Func<int, bool> alsoIsEven = i => (i % 2) == 0; 4:  5: // but the delegate instances cannot be directly assigned, strongly typed! 6: // ERROR: cannot convert type... 7: isEven = alsoIsEven; 8:  9: // however, you can assign by wrapping in a new instance: 10: isEven = new Predicate<int>(alsoIsEven); 11: alsoIsEven = new Func<int, bool>(isEven); So, the general advice that seems to come from most developers is that Predicate<T> is still supported, but we should use Func<T, bool> for consistency in .NET 3.5 and above. Sidebar: Func as a Generator for Unit Testing One area of difficulty in unit testing can be unit testing code that is based on time of day.  We’d still want to unit test our code to make sure the logic is accurate, but we don’t want the results of our unit tests to be dependent on the time they are run. One way (of many) around this is to create an internal generator that will produce the “current” time of day.  This would default to returning result from DateTime.Now (or some other method), but we could inject specific times for our unit testing.  Generators are typically methods that return (generate) a value for use in a class/method. For example, say we are creating a CacheItem<T> class that represents an item in the cache, and we want to make sure the item shows as expired if the age is more than 30 seconds.  Such a class could look like: 1: // responsible for maintaining an item of type T in the cache 2: public sealed class CacheItem<T> 3: { 4: // helper method that returns the current time 5: private static Func<DateTime> _timeGenerator = () => DateTime.Now; 6:  7: // allows internal access to the time generator 8: internal static Func<DateTime> TimeGenerator 9: { 10: get { return _timeGenerator; } 11: set { _timeGenerator = value; } 12: } 13:  14: // time the item was cached 15: public DateTime CachedTime { get; private set; } 16:  17: // the item cached 18: public T Value { get; private set; } 19:  20: // item is expired if older than 30 seconds 21: public bool IsExpired 22: { 23: get { return _timeGenerator() - CachedTime > TimeSpan.FromSeconds(30.0); } 24: } 25:  26: // creates the new cached item, setting cached time to "current" time 27: public CacheItem(T value) 28: { 29: Value = value; 30: CachedTime = _timeGenerator(); 31: } 32: } Then, we can use this construct to unit test our CacheItem<T> without any time dependencies: 1: var baseTime = DateTime.Now; 2:  3: // start with current time stored above (so doesn't drift) 4: CacheItem<int>.TimeGenerator = () => baseTime; 5:  6: var target = new CacheItem<int>(13); 7:  8: // now add 15 seconds, should still be non-expired 9: CacheItem<int>.TimeGenerator = () => baseTime.AddSeconds(15); 10:  11: Assert.IsFalse(target.IsExpired); 12:  13: // now add 31 seconds, should now be expired 14: CacheItem<int>.TimeGenerator = () => baseTime.AddSeconds(31); 15:  16: Assert.IsTrue(target.IsExpired); Now we can unit test for 1 second before, 1 second after, 1 millisecond before, 1 day after, etc.  Func delegates can be a handy tool for this type of value generation to support more testable code.  Summary Generic delegates give us a lot of power to make truly generic algorithms and classes.  The Func family of delegates is a great way to be able to specify functions to calculate a result based on 0-16 arguments.  Stay tuned in the weeks that follow for other generic delegates in the .NET Framework!   Tweet Technorati Tags: .NET, C#, CSharp, Little Wonders, Generics, Func, Delegates

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  • Tap into MySQL's Amazing Performance Results with the Performance Tuning Course

    - by Antoinette O'Sullivan
    Want to leverage the high-speed load utilities, distinctive memory caches, full text indexes, and other performance-enhancing mechanisms that MySQL offers to fuel today's critical business systems. The authentic MySQL Performance Tuning course, in 4 days, teaches you to evaluate the MySQL architecture, learn to use the tools, configure the database for performance, tune application and SQL code, tune the server, examine the storage engines, assess the application architecture, and learn general tuning concepts. You can take this course in one the following three ways: Training-on-Demand: Access the streaming video, instructor delivery of this course from your own desk, at your own pace. Book time for hands-on practice when it suits you. Live-Virtual Class: Take this instructor-led class live from your own desk. With 700 events on the schedule you are sure to find a time and date to suit you! In-Class: Travel to a classroom to take this class. A sample of events on the schedule are as follows.  Location  Date  Delivery Language  Hamburg, Germany  22 October 2012  German  Prague, Czech Republic  1 October 2012  Czech  Warsaw, Poland  3 December 2012  Polish  London, England  19 November 2012  English  Rome, Italy  23 October 2012  Italian Lisbon, Portugal  6 November 2012  European Portugese  Aix en Provence, France  4 September 2012   French  Strasbourg, France 16 October 2012   French  Nieuwegein, Netherlands 26 November 2012   Dutch  Madrid, Spain 17 December 2012   Spanish  Mechelen, Belgium  1 October 2012  English  Riga, Latvia  10 December 2012  Latvian  Petaling Jaya, Malaysia  10 September 2012 English   Edmonton, Canada 10 December 2012   English  Vancouver, Canada 10 December 2012   English  Ottawa, Canada 26 November 2012   English  Toronto, Canada 26 November 2012   English  Montreal, Canada 26 November 2012   English  Mexico City, Mexico 10 September 2012   Spanish  Sao Paolo, Brazil 26 November 2012  Brazilian Portugese   Tokyo, Japan 19 November 2012   Japanese  Tokyo, Japan  19 November 2012  Japanese For further information on this class, or to register your interest in additional events, go to the Oracle University Portal: http://oracle.com/education/mysql

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  • The Dispose Pattern (and FxCop warnings)

    - by Scott Dorman
    [This is actually a response to Bill’s blog post, but since it isn’t possible to leave this as a comment on his blog it’s a post here.] There are many different ways to implement the Dispose pattern correctly. Some are (in my opinion) better than others. In Bill’s blog post he presents a particular pattern, which is an excerpt from his book (Effective C#). The issue centers around the fact that a reader took the code sample presented in the book and ran FxCop (Code Analysis) on it, which generated a warning: “Ensure that base.Dispose() is always called.” The “lesson learned” that Bill presents is that “tools are there to help us, not control us.” While I completely agree with the belief that tools are there to help us, I think it’s important to understand why FxCop is raising this particular warning. The code presented in Bill’s book looks like: // Have its own disposed flag.private bool disposed = false;protected override void Dispose(bool isDisposing){ // Don't dispose more than once. if (disposed) return; if (isDisposing) { // TODO: free managed resources here. } // TODO: free unmanaged resources here. // Let the base class free its resources. // Base class is responsible for calling // GC.SuppressFinalize( ) base.Dispose(isDisposing); // Set derived class disposed flag: disposed = true;} This code does follow all of the guidelines for implementing the Dispose pattern. In this case, it’s presumably part of a larger example showing how to implement the pattern as part of a base class. The reason FxCop is warning you about this code is the first if statement in the Dispose method, which will cause the method to exit if disposed is true. The problem here is that there is the possibility that if the disposed flag is true, the call to base.Dispose() will never be executed. As Bill points out, it is possible for some other code elsewhere in the class to set this flag. He states that this is an “unlikely occurrence.” While that is probably true, it can be a potentially dangerous assumption to make and is one that can be easily corrected. By changing the code slightly you can remove this assumption and correct the FxCop violation. private bool disposed = false;protected override void Dispose(bool disposing){ if (!disposed) { if (disposing) { // Dispose managed resources. } // Dispose unmanaged resources. disposed = true; } base.Dispose(disposing);} Using this implementation allows the call to base.Dispose() to always occur, which ensures that the the disposal chain is always properly followed. Technorati Tags: .NET,C#,Dispose Pattern

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  • Configure Jenkins and Tomcat using Puppet on Vagrant

    - by ex3v
    I'm playing with setting up my first Spring + jenkins + Tomcat CI dev environment. For now it's just a test/fun phase, but in the near future I'll be starting new project with my coworkers. That's the reason that I want development environment virtualized and exactly te same on every development machine, as well as on production server. I choosen to use Vagrant and to try to write puppet scripts that not only install everything, but also configure everything so each of us will have the same jenkins plugins, same jenkins and tomcat login and password, and literally after calling vagrant up we are ready to work. What I managed to do so far is installation of stuff needed and port forwarding. My vagrantfile looks like this (comments stripped): VAGRANTFILE_API_VERSION = "2" Vagrant.configure(VAGRANTFILE_API_VERSION) do |config| config.vm.box = "precise32" config.vm.box_url = "http://files.vagrantup.com/precise32.box" config.vm.network :forwarded_port, guest: 80, host: 8090 config.vm.network :forwarded_port, guest: 8080, host: 8091 config.vm.network :private_network, ip: "192.168.33.10" config.vm.provision :puppet do |puppet| puppet.manifests_path = "puppet/" puppet.manifest_file = "default.pp" puppet.options = ['--verbose'] end end And this is my puppet file: Exec { path => [ "/bin/", "/sbin/" , "/usr/bin/", "/usr/sbin/" ] } class system-update { exec { 'apt-get update': command => 'apt-get update', } $sysPackages = [ "build-essential" ] package { $sysPackages: ensure => "installed", require => Exec['apt-get update'], } } class tomcat { package { "tomcat": ensure => present, require => Class["system-update"], } service { "tomcat": ensure => "running", require => Package["tomcat"], } } class jenkins { package { "jenkins": ensure => present, require => Class["system-update"], } service { "jenkins": ensure => "running", require => Package["jenkins"], } } include system-update include tomcat include jenkins Now, when I hit vagrant provision and go to http://localhost:8091/ I can see jenkins running, so above script works good. Next step is configurating jenkins and tomcat by extending above puppet scripts. I'm pretty green when it comes to CI. After wandering around web I've found few tutorials about jenkins configuration (here's one of them). I really want to move configuration presented in this tutorial to puppet file, so when I spread my vagrantfile and puppet file between my coworkers, I will be sure that everyone has exactly te same setup. Unfortunately I'm also green about using puppet, I don't know how to do this. Any help will be apreciated.

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  • Certification Notes: 70-583 Designing and Developing Windows Azure Applications

    - by BuckWoody
    It’s time for another certification, and we’ve just release the 70-583 exam on Windows Azure. I’ve blogged my “study plans” here before on other certifications, so I thought I would do the same for this one. I’ll also need to take exam 70-513 and 70-516; but I’ll post my notes on those separately. None of these are “brain dumps” or any questions from the actual tests - just the books, links and notes I have from my studies. I’ll update these references as I’m studying, so bookmark this site and watch my Twitter and Facebook posts for when I’ll update them, or just subscribe to the RSS feed. A “Green” color on the check-block means I’ve done that part so far, red means I haven’t. First, I need to refresh my memory on some basic coding, so along with the Azure-specific information I’m reading the following general programming books: Introducing Microsoft .NET (Pro-Developer): http://www.amazon.com/Introducing-Microsoft-Pro-Developer-David-Platt/dp/0735619182/ref=sr_1_1?s=books&ie=UTF8&qid=1296339237&sr=1-1 Head First C#, 2E: A Learner's Guide to Real-World Programming with Visual C# and .NET: http://www.amazon.com/Head-First-2E-Real-World-Programming/dp/1449380344/ref=sr_1_1?ie=UTF8&qid=1296339176&sr=8-1 Microsoft Visual C# 2008 Step by Step : http://www.amazon.com/Microsoft-Visual-2008-Step/dp/0735624305/ref=sr_1_1?s=books&ie=UTF8&qid=1296339208&sr=1-1 c The first place to start is at the official site for the certification. That’s here: http://www.microsoft.com/learning/en/us/Exam.aspx?ID=70-583&Locale=en-us c On that page you’ll find several resources, and the first you should follow is the “Save to my learning” so you have a place to track everything. Then click the “Related Learning Plans” link and follow the videos and read the documentation in each of those bullets. There are six areas on the learning plan that you should focus on - make sure you open the learning plan to drill into the specifics. c Designing Data Storage Architecture (18%) Books I’m Reading: Links: My Notes: c Optimizing Data Access and Messaging (17%) Books I’m Reading: Links: My Notes: c Designing the Application Architecture (19%) Books I’m Reading: Links: My Notes: c Preparing for Application and Service Deployment (15%) Books I’m Reading: Links: My Notes: c Investigating and Analyzing Applications (16%) Books I’m Reading: Links: My Notes: c Designing Integrated Solutions (15%) Books I’m Reading: Links: My Notes:

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  • Patterns for Handling Changing Property Sets in C++

    - by Bhargav Bhat
    I have a bunch "Property Sets" (which are simple structs containing POD members). I'd like to modify these property sets (eg: add a new member) at run time so that the definition of the property sets can be externalized and the code itself can be re-used with multiple versions/types of property sets with minimal/no changes. For example, a property set could look like this: struct PropSetA { bool activeFlag; int processingCount; /* snip few other such fields*/ }; But instead of setting its definition in stone at compile time, I'd like to create it dynamically at run time. Something like: class PropSet propSetA; propSetA("activeFlag",true); //overloading the function call operator propSetA("processingCount",0); And the code dependent on the property sets (possibly in some other library) will use the data like so: bool actvFlag = propSet["activeFlag"]; if(actvFlag == true) { //Do Stuff } The current implementation behind all of this is as follows: class PropValue { public: // Variant like class for holding multiple data-types // overloaded Conversion operator. Eg: operator bool() { return (baseType == BOOLEAN) ? this->ToBoolean() : false; } // And a method to create PropValues various base datatypes static FromBool(bool baseValue); }; class PropSet { public: // overloaded[] operator for adding properties void operator()(std::string propName, bool propVal) { propMap.insert(std::make_pair(propName, PropVal::FromBool(propVal))); } protected: // the property map std::map<std::string, PropValue> propMap; }; This problem at hand is similar to this question on SO and the current approach (described above) is based on this answer. But as noted over at SO this is more of a hack than a proper solution. The fundamental issues that I have with this approach are as follows: Extending this for supporting new types will require significant code change. At the bare minimum overloaded operators need to be extended to support the new type. Supporting complex properties (eg: struct containing struct) is tricky. Supporting a reference mechanism (needed for an optimization of not duplicating identical property sets) is tricky. This also applies to supporting pointers and multi-dimensional arrays in general. Are there any known patterns for dealing with this scenario? Essentially, I'm looking for the equivalent of the visitor pattern, but for extending class properties rather than methods. Edit: Modified problem statement for clarity and added some more code from current implementation.

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  • How to TDD test that objects are being added to a collection if the collection is private?

    - by Joshua Harris
    Assume that I planned to write a class that worked something like this: public class GameCharacter { private Collection<CharacterEffect> _collection; public void Add(CharacterEffect e) { ... } public void Remove(CharacterEffect e) { ... } public void Contains(CharacterEffect e) { ... } } When added an effect does something to the character and is then added to the _collection. When it is removed the effect reverts the change to the character and is removed from the _collection. It's easy to test if the effect was applied to the character, but how do I test that the effect was added to _collection? What test could I write to start constructing this class. I could write a test where Contains would return true for a certain effect being in _collection, but I can't arrange a case where that function would return true because I haven't implemented the Add method that is needed to place things in _collection. Ok, so since Contains is dependent on having Add working, then why don't I try to create Add first. Well for my first test I need to try and figure out if the effect was added to the _collection. How would I do that? The only way to see if an effect is in _collection is with the Contains function. The only way that I could think to test this would be to use a FakeCollection that Mocks the Add, Remove, and Contains of a real collection, but I don't want _collection being affected by outside sources. I don't want to add a setEffects(Collection effects) function, because I do not want the class to have that functionality. The one thing that I am thinking could work is this: public class GameCharacter<C extends Collection> { private Collection<CharacterEffect> _collection; public GameCharacter() { _collection = new C<CharacterEffect>(); } } But, that is just silly making me declare what some private data structures type is on every declaration of the character. Is there a way for me to test this without breaking TDD principles while still allowing me to keep my collection private?

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  • A Generic Boolean Value Converter

    - by codingbloke
    On fairly regular intervals a question on Stackoverflow like this one:  Silverlight Bind to inverse of boolean property value appears.  The same answers also regularly appear.  They all involve an implementation of IValueConverter and basically include the same boilerplate code. The required output type sometimes varies, other examples that have passed by are Boolean to Brush and Boolean to String conversions.  Yet the code remains pretty much the same.  There is therefore a good case to create a generic Boolean to value converter to contain this common code and then just specialise it for use in Xaml. Here is the basic converter:- BoolToValueConverter using System; using System.Windows.Data; namespace SilverlightApplication1 {     public class BoolToValueConverter<T> : IValueConverter     {         public T FalseValue { get; set; }         public T TrueValue { get; set; }         public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)         {             if (value == null)                 return FalseValue;             else                 return (bool)value ? TrueValue : FalseValue;         }         public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)         {             return value.Equals(TrueValue);         }     } } With this generic converter in place it easy to create a set of converters for various types.  For example here are all the converters mentioned so far:- Value Converters using System; using System.Windows; using System.Windows.Media; namespace SilverlightApplication1 {     public class BoolToStringConverter : BoolToValueConverter<String> { }     public class BoolToBrushConverter : BoolToValueConverter<Brush> { }     public class BoolToVisibilityConverter : BoolToValueConverter<Visibility> { }     public class BoolToObjectConverter : BoolToValueConverter<Object> { } } With the specialised converters created they can be specified in a Resources property on a user control like this:- <local:BoolToBrushConverter x:Key="Highlighter" FalseValue="Transparent" TrueValue="Yellow" /> <local:BoolToStringConverter x:Key="CYesNo" FalseValue="No" TrueValue="Yes" /> <local:BoolToVisibilityConverter x:Key="InverseVisibility" TrueValue="Collapsed" FalseValue="Visible" />

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  • Maven Integrated View for NetBeans IDE

    - by Geertjan
    Started working on an oft-heard request from Kirk Pepperdine for an integrated view for multimodule builds for Maven projects in NetBeans IDE, as explained here. I suddenly had some kind of brainwave and solved all the remaining problems I had, by delegating to the LogicalViewProvider's node, instead of the project's node, which means I inherit all the icons, actions, package nodes, and anything else that was originally defined within the original project, in this case for the open source JAnnocessor project: Above, you can see that the Maven submodules can either be edited in-line, i.e., within the parent project, or separately, by opening them in the traditional NetBeans way. Get the module here: http://plugins.netbeans.org/plugin/45180/?show=true Some people out there might be interested in how this is achieved. First, hide the original ModulesNodeFactory in the layer. Then create the following class, which creates what you see in the screenshot above: import java.util.ArrayList; import java.util.List; import javax.swing.event.ChangeListener; import org.netbeans.api.project.Project; import org.netbeans.spi.project.SubprojectProvider; import org.netbeans.spi.project.ui.LogicalViewProvider; import org.netbeans.spi.project.ui.support.NodeFactory; import org.netbeans.spi.project.ui.support.NodeList; import org.openide.nodes.FilterNode; import org.openide.nodes.Node; @NodeFactory.Registration(projectType = "org-netbeans-modules-maven", position = 400) public class ModulesNodeFactory2 implements NodeFactory { @Override public NodeList<?> createNodes(Project prjct) { return new MavenModulesNodeList(prjct); } private class MavenModulesNodeList implements NodeList<Project> { private final Project project; public MavenModulesNodeList(Project prjct) { this.project = prjct; } @Override public List<Project> keys() { return new ArrayList<Project>( project.getLookup(). lookup(SubprojectProvider.class).getSubprojects()); } @Override public Node node(final Project project) { Node node = project.getLookup().lookup(LogicalViewProvider.class).createLogicalView(); return new FilterNode(node, new FilterNode.Children(node)); } @Override public void addChangeListener(ChangeListener cl) { } @Override public void removeChangeListener(ChangeListener cl) { } @Override public void addNotify() { } @Override public void removeNotify() { } } } Considering that there's only about 5 actual statements above, it's pretty amazing how much can be achieved with so little code. The NetBeans APIs really are very cool. Hope you like it, Kirk!

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