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• How to distinguish between new and returning anonymous Drupal users?

  - by Matt V.

  Is there an easy way (or a module) in Drupal to distinguish between anonymous users who have never created an account versus those who are returning but are not currently logged in? For non-returning (ie, completely new) users, I'd like to have a front page that is very streamlined and focused on registration as the call-to-action. However, if someone is a returning user but not currently logged in, I'd like to present a lot more information on the front page and have login as the main call-to-action. I realize both pages would still need to have both login and register options available, I just want to make the focus significantly different between the two.

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• An Introduction to Meteor

  - by Stephen.Walther

  The goal of this blog post is to give you a brief introduction to Meteor which is a framework for building Single Page Apps. In this blog entry, I provide a walkthrough of building a simple Movie database app. What is special about Meteor? Meteor has two jaw-dropping features: Live HTML – If you make any changes to the HTML, CSS, JavaScript, or data on the server then every client shows the changes automatically without a browser refresh. For example, if you change the background color of a page to yellow then every open browser will show the new yellow background color without a refresh. Or, if you add a new movie to a collection of movies, then every open browser will display the new movie automatically. With Live HTML, users no longer need a refresh button. Changes to an application happen everywhere automatically without any effort. The Meteor framework handles all of the messy details of keeping all of the clients in sync with the server for you. Latency Compensation – When you modify data on the client, these modifications appear as if they happened on the server without any delay. For example, if you create a new movie then the movie appears instantly. However, that is all an illusion. In the background, Meteor updates the database with the new movie. If, for whatever reason, the movie cannot be added to the database then Meteor removes the movie from the client automatically. Latency compensation is extremely important for creating a responsive web application. You want the user to be able to make instant modifications in the browser and the framework to handle the details of updating the database without slowing down the user. Installing Meteor Meteor is licensed under the open-source MIT license and you can start building production apps with the framework right now. Be warned that Meteor is still in the “early preview” stage. It has not reached a 1.0 release. According to the Meteor FAQ, Meteor will reach version 1.0 in “More than a month, less than a year.” Don’t be scared away by that. You should be aware that, unlike most open source projects, Meteor has financial backing. The Meteor project received an $11.2 million round of financing from Andreessen Horowitz. So, it would be a good bet that this project will reach the 1.0 mark. And, if it doesn’t, the framework as it exists right now is still very powerful. Meteor runs on top of Node.js. You write Meteor apps by writing JavaScript which runs both on the client and on the server. You can build Meteor apps on Windows, Mac, or Linux (Although the support for Windows is still officially unofficial). If you want to install Meteor on Windows then download the MSI from the following URL: http://win.meteor.com/ If you want to install Meteor on Mac/Linux then run the following CURL command from your terminal: curl https://install.meteor.com | /bin/sh Meteor will install all of its dependencies automatically including Node.js. However, I recommend that you install Node.js before installing Meteor by installing Node.js from the following address: http://nodejs.org/ If you let Meteor install Node.js then Meteor won’t install NPM which is the standard package manager for Node.js. If you install Node.js and then you install Meteor then you get NPM automatically. Creating a New Meteor App To get a sense of how Meteor works, I am going to walk through the steps required to create a simple Movie database app. Our app will display a list of movies and contain a form for creating a new movie. The first thing that we need to do is create our new Meteor app. Open a command prompt/terminal window and execute the following command: Meteor create MovieApp After you execute this command, you should see something like the following: Follow the instructions: execute cd MovieApp to change to your MovieApp directory, and run the meteor command. Executing the meteor command starts Meteor on port 3000. Open up your favorite web browser and navigate to http://localhost:3000 and you should see the default Meteor Hello World page: Open up your favorite development environment to see what the Meteor app looks like. Open the MovieApp folder which we just created. Here’s what the MovieApp looks like in Visual Studio 2012: Notice that our MovieApp contains three files named MovieApp.css, MovieApp.html, and MovieApp.js. In other words, it contains a Cascading Style Sheet file, an HTML file, and a JavaScript file. Just for fun, let’s see how the Live HTML feature works. Open up multiple browsers and point each browser at http://localhost:3000. Now, open the MovieApp.html page and modify the text “Hello World!” to “Hello Cruel World!” and save the change. The text in all of the browsers should update automatically without a browser refresh. Pretty amazing, right? Controlling Where JavaScript Executes You write a Meteor app using JavaScript. Some of the JavaScript executes on the client (the browser) and some of the JavaScript executes on the server and some of the JavaScript executes in both places. For a super simple app, you can use the Meteor.isServer and Meteor.isClient properties to control where your JavaScript code executes. For example, the following JavaScript contains a section of code which executes on the server and a section of code which executes in the browser: if (Meteor.isClient) { console.log("Hello Browser!"); } if (Meteor.isServer) { console.log("Hello Server!"); } console.log("Hello Browser and Server!"); When you run the app, the message “Hello Browser!” is written to the browser JavaScript console. The message “Hello Server!” is written to the command/terminal window where you ran Meteor. Finally, the message “Hello Browser and Server!” is execute on both the browser and server and the message appears in both places. For simple apps, using Meteor.isClient and Meteor.isServer to control where JavaScript executes is fine. For more complex apps, you should create separate folders for your server and client code. Here are the folders which you can use in a Meteor app: · client – This folder contains any JavaScript which executes only on the client. · server – This folder contains any JavaScript which executes only on the server. · common – This folder contains any JavaScript code which executes on both the client and server. · lib – This folder contains any JavaScript files which you want to execute before any other JavaScript files. · public – This folder contains static application assets such as images. For the Movie App, we need the client, server, and common folders. Delete the existing MovieApp.js, MovieApp.html, and MovieApp.css files. We will create new files in the right locations later in this walkthrough. Combining HTML, CSS, and JavaScript Files Meteor combines all of your JavaScript files, and all of your Cascading Style Sheet files, and all of your HTML files automatically. If you want to create one humongous JavaScript file which contains all of the code for your app then that is your business. However, if you want to build a more maintainable application, then you should break your JavaScript files into many separate JavaScript files and let Meteor combine them for you. Meteor also combines all of your HTML files into a single file. HTML files are allowed to have the following top-level elements: <head> — All <head> files are combined into a single <head> and served with the initial page load. <body> — All <body> files are combined into a single <body> and served with the initial page load. <template> — All <template> files are compiled into JavaScript templates. Because you are creating a single page app, a Meteor app typically will contain a single HTML file for the <head> and <body> content. However, a Meteor app typically will contain several template files. In other words, all of the interesting stuff happens within the <template> files. Displaying a List of Movies Let me start building the Movie App by displaying a list of movies. In order to display a list of movies, we need to create the following four files: · client\movies.html – Contains the HTML for the <head> and <body> of the page for the Movie app. · client\moviesTemplate.html – Contains the HTML template for displaying the list of movies. · client\movies.js – Contains the JavaScript for supplying data to the moviesTemplate. · server\movies.js – Contains the JavaScript for seeding the database with movies. After you create these files, your folder structure should looks like this: Here’s what the client\movies.html file looks like: <head> <title>My Movie App</title> </head> <body> <h1>Movies</h1> {{> moviesTemplate }} </body>   Notice that it contains <head> and <body> top-level elements. The <body> element includes the moviesTemplate with the syntax {{> moviesTemplate }}. The moviesTemplate is defined in the client/moviesTemplate.html file: <template name="moviesTemplate"> <ul> {{#each movies}} <li> {{title}} </li> {{/each}} </ul> </template> By default, Meteor uses the Handlebars templating library. In the moviesTemplate above, Handlebars is used to loop through each of the movies using {{#each}}…{{/each}} and display the title for each movie using {{title}}. The client\movies.js JavaScript file is used to bind the moviesTemplate to the Movies collection on the client. Here’s what this JavaScript file looks like: // Declare client Movies collection Movies = new Meteor.Collection("movies"); // Bind moviesTemplate to Movies collection Template.moviesTemplate.movies = function () { return Movies.find(); }; The Movies collection is a client-side proxy for the server-side Movies database collection. Whenever you want to interact with the collection of Movies stored in the database, you use the Movies collection instead of communicating back to the server. The moviesTemplate is bound to the Movies collection by assigning a function to the Template.moviesTemplate.movies property. The function simply returns all of the movies from the Movies collection. The final file which we need is the server-side server\movies.js file: // Declare server Movies collection Movies = new Meteor.Collection("movies"); // Seed the movie database with a few movies Meteor.startup(function () { if (Movies.find().count() == 0) { Movies.insert({ title: "Star Wars", director: "Lucas" }); Movies.insert({ title: "Memento", director: "Nolan" }); Movies.insert({ title: "King Kong", director: "Jackson" }); } }); The server\movies.js file does two things. First, it declares the server-side Meteor Movies collection. When you declare a server-side Meteor collection, a collection is created in the MongoDB database associated with your Meteor app automatically (Meteor uses MongoDB as its database automatically). Second, the server\movies.js file seeds the Movies collection (MongoDB collection) with three movies. Seeding the database gives us some movies to look at when we open the Movies app in a browser. Creating New Movies Let me modify the Movies Database App so that we can add new movies to the database of movies. First, I need to create a new template file – named client\movieForm.html – which contains an HTML form for creating a new movie: <template name="movieForm"> <fieldset> <legend>Add New Movie</legend> <form> <div> <label> Title: <input id="title" /> </label> </div> <div> <label> Director: <input id="director" /> </label> </div> <div> <input type="submit" value="Add Movie" /> </div> </form> </fieldset> </template> In order for the new form to show up, I need to modify the client\movies.html file to include the movieForm.html template. Notice that I added {{> movieForm }} to the client\movies.html file: <head> <title>My Movie App</title> </head> <body> <h1>Movies</h1> {{> moviesTemplate }} {{> movieForm }} </body> After I make these modifications, our Movie app will display the form: The next step is to handle the submit event for the movie form. Below, I’ve modified the client\movies.js file so that it contains a handler for the submit event raised when you submit the form contained in the movieForm.html template: // Declare client Movies collection Movies = new Meteor.Collection("movies"); // Bind moviesTemplate to Movies collection Template.moviesTemplate.movies = function () { return Movies.find(); }; // Handle movieForm events Template.movieForm.events = { 'submit': function (e, tmpl) { // Don't postback e.preventDefault(); // create the new movie var newMovie = { title: tmpl.find("#title").value, director: tmpl.find("#director").value }; // add the movie to the db Movies.insert(newMovie); } }; The Template.movieForm.events property contains an event map which maps event names to handlers. In this case, I am mapping the form submit event to an anonymous function which handles the event. In the event handler, I am first preventing a postback by calling e.preventDefault(). This is a single page app, no postbacks are allowed! Next, I am grabbing the new movie from the HTML form. I’m taking advantage of the template find() method to retrieve the form field values. Finally, I am calling Movies.insert() to insert the new movie into the Movies collection. Here, I am explicitly inserting the new movie into the client-side Movies collection. Meteor inserts the new movie into the server-side Movies collection behind the scenes. When Meteor inserts the movie into the server-side collection, the new movie is added to the MongoDB database associated with the Movies app automatically. If server-side insertion fails for whatever reasons – for example, your internet connection is lost – then Meteor will remove the movie from the client-side Movies collection automatically. In other words, Meteor takes care of keeping the client Movies collection and the server Movies collection in sync. If you open multiple browsers, and add movies, then you should notice that all of the movies appear on all of the open browser automatically. You don’t need to refresh individual browsers to update the client-side Movies collection. Meteor keeps everything synchronized between the browsers and server for you. Removing the Insecure Module To make it easier to develop and debug a new Meteor app, by default, you can modify the database directly from the client. For example, you can delete all of the data in the database by opening up your browser console window and executing multiple Movies.remove() commands. Obviously, enabling anyone to modify your database from the browser is not a good idea in a production application. Before you make a Meteor app public, you should first run the meteor remove insecure command from a command/terminal window: Running meteor remove insecure removes the insecure package from the Movie app. Unfortunately, it also breaks our Movie app. We’ll get an “Access denied” error in our browser console whenever we try to insert a new movie. No worries. I’ll fix this issue in the next section. Creating Meteor Methods By taking advantage of Meteor Methods, you can create methods which can be invoked on both the client and the server. By taking advantage of Meteor Methods you can: 1. Perform form validation on both the client and the server. For example, even if an evil hacker bypasses your client code, you can still prevent the hacker from submitting an invalid value for a form field by enforcing validation on the server. 2. Simulate database operations on the client but actually perform the operations on the server. Let me show you how we can modify our Movie app so it uses Meteor Methods to insert a new movie. First, we need to create a new file named common\methods.js which contains the definition of our Meteor Methods: Meteor.methods({ addMovie: function (newMovie) { // Perform form validation if (newMovie.title == "") { throw new Meteor.Error(413, "Missing title!"); } if (newMovie.director == "") { throw new Meteor.Error(413, "Missing director!"); } // Insert movie (simulate on client, do it on server) return Movies.insert(newMovie); } }); The addMovie() method is called from both the client and the server. This method does two things. First, it performs some basic validation. If you don’t enter a title or you don’t enter a director then an error is thrown. Second, the addMovie() method inserts the new movie into the Movies collection. When called on the client, inserting the new movie into the Movies collection just updates the collection. When called on the server, inserting the new movie into the Movies collection causes the database (MongoDB) to be updated with the new movie. You must add the common\methods.js file to the common folder so it will get executed on both the client and the server. Our folder structure now looks like this: We actually call the addMovie() method within our client code in the client\movies.js file. Here’s what the updated file looks like: // Declare client Movies collection Movies = new Meteor.Collection("movies"); // Bind moviesTemplate to Movies collection Template.moviesTemplate.movies = function () { return Movies.find(); }; // Handle movieForm events Template.movieForm.events = { 'submit': function (e, tmpl) { // Don't postback e.preventDefault(); // create the new movie var newMovie = { title: tmpl.find("#title").value, director: tmpl.find("#director").value }; // add the movie to the db Meteor.call( "addMovie", newMovie, function (err, result) { if (err) { alert("Could not add movie " + err.reason); } } ); } }; The addMovie() method is called – on both the client and the server – by calling the Meteor.call() method. This method accepts the following parameters: · The string name of the method to call. · The data to pass to the method (You can actually pass multiple params for the data if you like). · A callback function to invoke after the method completes. In the JavaScript code above, the addMovie() method is called with the new movie retrieved from the HTML form. The callback checks for an error. If there is an error then the error reason is displayed in an alert (please don’t use alerts for validation errors in a production app because they are ugly!). Summary The goal of this blog post was to provide you with a brief walk through of a simple Meteor app. I showed you how you can create a simple Movie Database app which enables you to display a list of movies and create new movies. I also explained why it is important to remove the Meteor insecure package from a production app. I showed you how to use Meteor Methods to insert data into the database instead of doing it directly from the client. I’m very impressed with the Meteor framework. The support for Live HTML and Latency Compensation are required features for many real world Single Page Apps but implementing these features by hand is not easy. Meteor makes it easy.

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• Ubuntu Software Center starts, then crashes before fully loaded [closed]

  - by Nathan Weisser

  Possible Duplicate: Software center not opening I am brand new to Linux and Ubuntu, and I couldn't install GIMP without the software center. I looked up earlier how to fix it, and it said to fix my sources list, and I did, but now i get a new error in the terminal. 2012-08-14 15:29:08,941 - softwarecenter.ui.gtk3.app - INFO - setting up proxy 'None' 2012-08-14 15:29:08,954 - softwarecenter.db.database - INFO - open() database: path=None use_axi=True use_agent=True 2012-08-14 15:29:09,407 - softwarecenter.ui.gtk3.app - INFO - building local database 2012-08-14 15:29:09,408 - softwarecenter.db.pkginfo_impl.aptcache - INFO - aptcache.open() 2012-08-14 15:29:17,308 - softwarecenter.db.update - WARNING - Problem creating rebuild path '/var/cache/software-center/xapian_rb'. 2012-08-14 15:29:17,309 - softwarecenter.db.update - WARNING - Please check you have the relevant permissions. 2012-08-14 15:29:17,309 - softwarecenter.db.database - INFO - open() database: path=None use_axi=True use_agent=True 2012-08-14 15:29:18,039 - softwarecenter.backend.reviews - WARNING - Could not get usefulness from server, no username in config file 2012-08-14 15:29:18,431 - softwarecenter.ui.gtk3.app - INFO - show_available_packages: search_text is '', app is None. 2012-08-14 15:29:19,153 - softwarecenter.db.pkginfo_impl.aptcache - INFO - aptcache.open() Traceback (most recent call last): File "/usr/bin/software-center", line 176, in <module> app.run(args) File "/usr/share/software-center/softwarecenter/ui/gtk3/app.py", line 1422, in run self.show_available_packages(args) File "/usr/share/software-center/softwarecenter/ui/gtk3/app.py", line 1352, in show_available_packages self.view_manager.set_active_view(ViewPages.AVAILABLE) File "/usr/share/software-center/softwarecenter/ui/gtk3/session/viewmanager.py", line 154, in set_active_view view_widget.init_view() File "/usr/share/software-center/softwarecenter/ui/gtk3/panes/availablepane.py", line 136, in init_view SoftwarePane.init_view(self) File "/usr/share/software-center/softwarecenter/ui/gtk3/panes/softwarepane.py", line 215, in init_view self.icons, self.show_ratings) File "/usr/share/software-center/softwarecenter/ui/gtk3/views/appview.py", line 69, in __init__ self.helper = AppPropertiesHelper(db, cache, icons) File "/usr/share/software-center/softwarecenter/ui/gtk3/models/appstore2.py", line 109, in __init__ softwarecenter.paths.APP_INSTALL_PATH) File "/usr/share/software-center/softwarecenter/db/categories.py", line 255, in parse_applications_menu category = self._parse_menu_tag(child) File "/usr/share/software-center/softwarecenter/db/categories.py", line 444, in _parse_menu_tag query = self._parse_include_tag(element) File "/usr/share/software-center/softwarecenter/db/categories.py", line 402, in _parse_include_tag xapian.Query.OP_AND) File "/usr/share/software-center/softwarecenter/db/categories.py", line 341, in _parse_and_or_not_tag operator_elem, xapian.Query(), xapian.Query.OP_OR) File "/usr/share/software-center/softwarecenter/db/categories.py", line 385, in _parse_and_or_not_tag q = self.db.xapian_parser.parse_query(s, File "/usr/share/software-center/softwarecenter/db/database.py", line 174, in xapian_parser xapian_parser = self._get_new_xapian_parser() File "/usr/share/software-center/softwarecenter/db/database.py", line 200, in _get_new_xapian_parser xapian_parser.set_database(self.xapiandb) File "/usr/share/software-center/softwarecenter/db/database.py", line 166, in xapiandb self._db_per_thread[thread_name] = self._get_new_xapiandb() File "/usr/share/software-center/softwarecenter/db/database.py", line 179, in _get_new_xapiandb xapiandb = xapian.Database(self._db_pathname) File "/usr/lib/python2.7/dist-packages/xapian/__init__.py", line 3666, in __init__ _xapian.Database_swiginit(self,_xapian.new_Database(*args)) xapian.DatabaseOpeningError: Couldn't detect type of database I'm not sure how to fix the errors, and I couldn't find a topic on them anywhere. Be nice, because I am a two-day old Linux user :/ Tell me if you need my Sources list

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• Big Data – Buzz Words: What is NoSQL – Day 5 of 21

  - by Pinal Dave

  In yesterday’s blog post we explored the basic architecture of Big Data . In this article we will take a quick look at one of the four most important buzz words which goes around Big Data – NoSQL. What is NoSQL? NoSQL stands for Not Relational SQL or Not Only SQL. Lots of people think that NoSQL means there is No SQL, which is not true – they both sound same but the meaning is totally different. NoSQL does use SQL but it uses more than SQL to achieve its goal. As per Wikipedia’s NoSQL Database Definition – “A NoSQL database provides a mechanism for storage and retrieval of data that uses looser consistency models than traditional relational databases.“ Why use NoSQL? A traditional relation database usually deals with predictable structured data. Whereas as the world has moved forward with unstructured data we often see the limitations of the traditional relational database in dealing with them. For example, nowadays we have data in format of SMS, wave files, photos and video format. It is a bit difficult to manage them by using a traditional relational database. I often see people using BLOB filed to store such a data. BLOB can store the data but when we have to retrieve them or even process them the same BLOB is extremely slow in processing the unstructured data. A NoSQL database is the type of database that can handle unstructured, unorganized and unpredictable data that our business needs it. Along with the support to unstructured data, the other advantage of NoSQL Database is high performance and high availability. Eventual Consistency Additionally to note that NoSQL Database may not provided 100% ACID (Atomicity, Consistency, Isolation, Durability) compliance.  Though, NoSQL Database does not support ACID they provide eventual consistency. That means over the long period of time all updates can be expected to propagate eventually through the system and data will be consistent. Taxonomy Taxonomy is the practice of classification of things or concepts and the principles. The NoSQL taxonomy supports column store, document store, key-value stores, and graph databases. We will discuss the taxonomy in detail in later blog posts. Here are few of the examples of the each of the No SQL Category. Column: Hbase, Cassandra, Accumulo Document: MongoDB, Couchbase, Raven Key-value : Dynamo, Riak, Azure, Redis, Cache, GT.m Graph: Neo4J, Allegro, Virtuoso, Bigdata As of now there are over 150 NoSQL Database and you can read everything about them in this single link. Tomorrow In tomorrow’s blog post we will discuss Buzz Word – Hadoop. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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• Using a SQL Prompt snippet with template parameters

  - by SQLDev

  As part of my product management role I regularly attend trade shows and man the Red Gate booth in the vendor exhibition hall. Amongst other things this involves giving product demos to customers. Our latest demo involves SQL Source Control and SQL Test in a continuous integration environment. In order to demonstrate quite how easy it is to set up our tools from scratch we start the demo by creating an entirely new database to link to source control, using an individual database name for each conference attendee. In SQL Server Management Studio this can be done either by selecting New Database from the Object Explorer or by executing “CREATE DATABASE DemoDB_John” in a query window. We recently extended the demo to include SQL Test. This uses an open source SQL Server unit testing framework called tSQLt (www.tsqlt.org), which has a CLR object that requires EXTERNAL_ACCESS to be set as follows: ALTER DATABASE DemoDB_John SET TRUSTWORTHY ON This isn’t hard to do, but if you’re giving demo after demo, this two-step process soon becomes tedious. This is where SQL Prompt snippets come into their own. I can create a snippet named create_demo_db for this following: CREATE DATABASE DemoDB_John GO USE DemoDB_John GO ALTER DATABASE DemoDB_John SET TRUSTWORTHY ON Now I just have to type the first few characters of the snippet name, select the snippet from SQL Prompt’s candidate list, and execute the code. Simple! The problem is that this can only work once due to the hard-coded database name. Luckily I can leverage a nice feature in SQL Server Management Studio called Template Parameters. If I modify my snippet to be: CREATE DATABASE <DBName,, DemoDB_> GO USE <DBName,, DemoDB_> GO ALTER DATABASE <DBName,, DemoDB_> SET TRUSTWORTHY ON Once I’ve invoked the snippet, I can press Ctrl-Shift-M, which calls up the Specify Values for Template Parameters dialog, where I can type in my database name just once. Now you can click OK and run the query. Easy. Ideally I’d like for SQL Prompt to auto-invoke the Template Parameter dialog for all snippets where it detects the angled bracket syntax, but typing in the keyboard shortcut is a small price to pay for the time savings.

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• 11g ???:Active Data Guard

  - by JaneZhang(???)

  ?Oracle 11g??,????(physical Standby)???redo???,???????,???mount??11g??,???redo???,????????read-only??,????Active Data Guard ???Active Data Guard,?????????????????,??????????????   Active Data Guard???????????,??,????????????,????????,????redo??,????????????,??????????? Oracle Active Data Guard ?Oracle Database Enterprise Edition?????,??????????????   ????Active Data Guard, ??????? read-only ????,???? ALTER DATABASE RECOVER MANAGED STANDBY DATABASE????????????:??????COMPATIBLE ????????11.0.0?  ???????Active Data Guard,???V$DATABASE????"READ ONLY WITH APPLY':      SQL> SELECT open_mode FROM V$DATABASE;      OPEN_MODE      --------------------      READ ONLY WITH APPLY   ????????????,???????real-time apply:   SQL>ALTER DATABASE RECOVER MANAGED STANDBY DATABASE USING CURRENT LOGFILE; ?????????read-only????????:    • Issue SELECT statements, including queries that require multiple sorts that leverage TEMP segments    • Use ALTER SESSION and ALTER SYSTEM statements    • Use SET ROLE    • Call stored procedures    • Use database links (dblinks) to write to remote databases    • Use stored procedures to call remote procedures via dblinks    • Use SET TRANSACTION READ ONLY for transaction level read consistency    • Issue complex queries (such as grouping SET queries and WITH CLAUSE queries) ??????????read-only????????:    • Any DMLs (excluding simple SELECT statements) or DDLs    • Query accessing local sequences    • DMLs to local temporary tables    ?????Active Data Guard ??: • ????????????????? • ???Oracle Real Application Clusters (Oracle RAC) ,?????? • RAC???RAC??    Oracle Data Guard ?????,,????????:    * ?????????????????:     http://docs.oracle.com/cd/B28359_01/server.111/b28294/create_ps.htm   * ???Oracle Real Application Clusters (Oracle RAC) ,??????:     http://www.oracle.com/technetwork/database/features/availability/maa-wp-10g-racprimarysingleinstance-131970.pdf   * RAC ???RAC ??:     http://www.oracle.com/technetwork/database/features/availability/maa-wp-10g-racprimaryracphysicalsta-131940.pdf  ??Active Data Guard???????,?????:    http://www.oracle.com/technetwork/database/features/availability/maa-wp-11gr1-activedataguard-1-128199.pdf     ??Oracle Maximum Availability Architecture Best Practices?????,???:   http://www.oracle.com/goto/maa

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• Authenticate by libpam-mysql and libnss-mysql (CentOS)

  - by Chris

  I'm trying to get MySQL to function as a backend for authenticating users on CentOS 6.3. So far I have successfully installed and configured libnss-mysql. I can test this by doing: # groups testuser testuser : sftp Testuser is a member of the sftp group in fact, all MySQL based useraccounts will be hardcoded to it. The sftp group is chrooted and forced to use internal-sftp so they cannot do anything but access their home directory. Then I configured pam-mysql and PAM to allow mysql logins. This also works.. When SELinux is not enforcing. When I do setenforce 1 users can no longer login. Error: Permission denied, please try again. This is my pam_mysql.conf file: users.host=localhost users.db_user=nss-pam-user users.db_passwd=*********** users.database=sftpusers users.table=users users.user_column=username users.password_column=password users.password_crypt=6 verbose=1 My /etc/pam.d/sshd: #%PAM-1.0 auth sufficient pam_sepermit.so auth include password-auth auth required pam_mysql.so config_file=/etc/pam_mysql.conf account sufficient pam_nologin.so account include password-auth account required pam_mysql.so config_file=/etc/pam_mysql.conf password include password-auth # pam_selinux.so close should be the first session rule session required pam_selinux.so close session required pam_loginuid.so # pam_selinux.so open should only be followed by sessions to be executed in the user context session required pam_selinux.so open env_params session optional pam_keyinit.so force revoke session include password-auth And to be complete the contents of some log files.. /var/logs/secure Nov 20 14:52:20 hostname unix_chkpwd[4891]: check pass; user unknown Nov 20 14:52:20 hostname unix_chkpwd[4891]: password check failed for user (testuser) Nov 20 14:52:20 hostname sshd[4880]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=192.168.10.107 user=testuser Nov 20 14:52:22 sftpusers sshd[4880]: Failed password for testuser from 192.168.10.107 port 51849 ssh2 /var/logs/audit/audit.log type=USER_AUTH msg=audit(1353420107.070:812): user pid=5285 uid=0 auid=500 ses=24 subj=unconfined_u:system_r:sshd_t:s0-s0:c0.c1023 msg='op=pubkey acct="testuser" exe="/usr/sbin/sshd" hostname=? addr=192.168.10.107 terminal=ssh res=failed' type=USER_AUTH msg=audit(1353420112.312:813): user pid=5285 uid=0 auid=500 ses=24 subj=unconfined_u:system_r:sshd_t:s0-s0:c0.c1023 msg='op=PAM:authentication acct="testuser" exe="/usr/sbin/sshd" hostname=192.168.10.107 addr=192.168.10.107 terminal=ssh res=failed' type=USER_AUTH msg=audit(1353420112.456:814): user pid=5285 uid=0 auid=500 ses=24 subj=unconfined_u:system_r:sshd_t:s0-s0:c0.c1023 msg='op=password acct="testuser" exe="/usr/sbin/sshd" hostname=? addr=192.168.10.107 terminal=ssh res=failed' I tried to let audit2why explain the problem but it remains silent even though there are some errors. Does anyone see the problem? Thanks! EDIT: Turns out it's almost working with setenforce 0 I can mkdir foobar but if I do a single ls I get an error: Received message too long 16777216

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• cant get connexion using MongoTor

  - by Abdelouahab Pp

  i was trying to change my code to make it asynchronous using MongoTor here is my simple code: class BaseHandler(tornado.web.RequestHandler): @property def db(self): if not hasattr(self,"_db"): _db = Database.connect('localhost:27017', 'essog') return _db @property def fs(self): if not hasattr(BaseHandler,"_fs"): _fs = gridfs.GridFS(self.db) return _fs class LoginHandler(BaseHandler): @tornado.web.asynchronous @tornado.gen.engine def post(self): email = self.get_argument("email") password = self.get_argument("pass1") try: search = yield tornado.gen.Task(self.db.users.find, {"prs.mail":email}) .... i got this error: Traceback (most recent call last): File "C:\Python27\lib\site-packages\tornado-2.4.post1-py2.7.egg\tornado\web.py", line 1043, in _stack_context_handle_exception raise_exc_info((type, value, traceback)) File "C:\Python27\lib\site-packages\tornado-2.4.post1-py2.7.egg\tornado\web.py", line 1162, in wrapper return method(self, *args, **kwargs) File "C:\Python27\lib\site-packages\tornado-2.4.post1-py2.7.egg\tornado\gen.py", line 122, in wrapper runner.run() File "C:\Python27\lib\site-packages\tornado-2.4.post1-py2.7.egg\tornado\gen.py", line 365, in run yielded = self.gen.send(next) File "G:\Mon projet\essog\handlers.py", line 92, in post search = yield tornado.gen.Task(self.db.users.find, {"prs.mail":email}) File "G:\Mon projet\essog\handlers.py", line 62, in db _db = Database.connect('localhost:27017', 'essog') File "build\bdist.win-amd64\egg\mongotor\database.py", line 131, in connect database.init(addresses, dbname, read_preference, **kwargs) File "build\bdist.win-amd64\egg\mongotor\database.py", line 62, in init ioloop_is_running = IOLoop.instance().running() AttributeError: 'SelectIOLoop' object has no attribute 'running' ERROR:tornado.access:500 POST /login (::1) 3.00ms and, excuse me for this other question, but how do i make distinct in this case? here is what worked in blocking mode: search = self.db.users.find({"prs.mail":email}).distinct("prs.mail")[0] Update: it seems that this error happenes when there is no Tornado running! it's the same error raised when using only the module in console. test = Database.connect("localhost:27017", "essog") --------------------------------------------------------------------------- AttributeError Traceback (most recent call last) in () ---- 1 test = Database.connect("localhost:27017", "essog") C:\Python27\lib\site-packages\mongotor-0.0.10-py2.7.egg\mongotor\database.pyc in connect(cls, addresses, dbname, read_preference, **kwargs) 131 132 database = Database() -- 133 database.init(addresses, dbname, read_preference, **kwargs) 134 135 return database C:\Python27\lib\site-packages\mongotor-0.0.10-py2.7.egg\mongotor\database.pyc in init(self, addresses, dbname, read_preference, **kwargs) 60 self._nodes.append(node) 61 --- 62 ioloop_is_running = IOLoop.instance().running() 63 self._config_nodes(callback=partial(self._on_config_node, ioloop_is_running)) 64 AttributeError: 'SelectIOLoop' object has no attribute 'running'

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• SQL SERVER – Securing TRUNCATE Permissions in SQL Server

  - by pinaldave

  Download the Script of this article from here. On December 11, 2010, Vinod Kumar, a Databases & BI technology evangelist from Microsoft Corporation, graced Ahmedabad by spending some time with the Community during the Community Tech Days (CTD) event. As he was running through a few demos, Vinod asked the audience one of the most fundamental and common interview questions – “What is the difference between a DELETE and TRUNCATE?“ Ahmedabad SQL Server User Group Expert Nakul Vachhrajani has come up with excellent solutions of the same. I must congratulate Nakul for this excellent solution and as a encouragement to User Group member, I am publishing the same article over here. Nakul Vachhrajani is a Software Specialist and systems development professional with Patni Computer Systems Limited. He has functional experience spanning legacy code deprecation, system design, documentation, development, implementation, testing, maintenance and support of complex systems, providing business intelligence solutions, database administration, performance tuning, optimization, product management, release engineering, process definition and implementation. He has comprehensive grasp on Database Administration, Development and Implementation with MS SQL Server and C, C++, Visual C++/C#. He has about 6 years of total experience in information technology. Nakul is an member of the Ahmedabad and Gandhinagar SQL Server User Groups, and actively contributes to the community by actively participating in multiple forums and websites like SQLAuthority.com, BeyondRelational.com, SQLServerCentral.com and many others. Please note: The opinions expressed herein are Nakul own personal opinions and do not represent his employer’s view in anyway. All data from everywhere here on Earth go through a series of  four distinct operations, identified by the words: CREATE, READ, UPDATE and DELETE, or simply, CRUD. Putting in Microsoft SQL Server terms, is the process goes like this: INSERT, SELECT, UPDATE and DELETE/TRUNCATE. Quite a few interesting responses were received and evaluated live during the session. To summarize them, the most important similarity that came out was that both DELETE and TRUNCATE participate in transactions. The major differences (not all) that came out of the exercise were: DELETE: DELETE supports a WHERE clause DELETE removes rows from a table, row-by-row Because DELETE moves row-by-row, it acquires a row-level lock Depending upon the recovery model of the database, DELETE is a fully-logged operation. Because DELETE moves row-by-row, it can fire off triggers TRUNCATE: TRUNCATE does not support a WHERE clause TRUNCATE works by directly removing the individual data pages of a table TRUNCATE directly occupies a table-level lock. (Because a lock is acquired, and because TRUNCATE can also participate in a transaction, it has to be a logged operation) TRUNCATE is, therefore, a minimally-logged operation; again, this depends upon the recovery model of the database Triggers are not fired when TRUNCATE is used (because individual row deletions are not logged) Finally, Vinod popped the big homework question that must be critically analyzed: “We know that we can restrict a DELETE operation to a particular user, but how can we restrict the TRUNCATE operation to a particular user?” After returning home and having a nice cup of coffee, I noticed that my gray cells immediately started to work. Below was the result of my research. As what is always said, the devil is in the details. Upon looking at the Permissions section for the TRUNCATE statement in Books On Line, the following jumps right out: “The minimum permission required is ALTER on table_name. TRUNCATE TABLE permissions default to the table owner, members of the sysadmin fixed server role, and the db_owner and db_ddladmin fixed database roles, and are not transferable. However, you can incorporate the TRUNCATE TABLE statement within a module, such as a stored procedure, and grant appropriate permissions to the module using the EXECUTE AS clause.“ Now, what does this mean? Unlike DELETE, one cannot directly assign permissions to a user/set of users allowing or revoking TRUNCATE rights. However, there is a way to circumvent this. It is important to recall that in Microsoft SQL Server, database engine security surrounds the concept of a “securable”, which is any object like a table, stored procedure, trigger, etc. Rights are assigned to a principal on a securable. Refer to the image below (taken from the SQL Server Books On Line). urable”, which is any object like a table, stored procedure, trigger, etc. Rights are assigned to a principal on a securable. Refer to the image below (taken from the SQL Server Books On Line). SETTING UP THE ENVIRONMENT – (01A_Truncate Table Permissions.sql) Script Provided at the end of the article. By the end of this demo, one will be able to do all the CRUD operations, except the TRUNCATE, and the other will only be able to execute the TRUNCATE. All you will need for this test is any edition of SQL Server 2008. (With minor changes, these scripts can be made to work with SQL 2005.) We begin by creating the following: 1.       A test database 2.        Two database roles: associated logins and users 3.       Switch over to the test database and create a test table. Then, add some data into it. I am using row constructors, which is new to SQL 2008. Creating the modules that will be used to enforce permissions 1.       We have already created one of the modules that we will be assigning permissions to. That module is the table: TruncatePermissionsTest 2.       We will now create two stored procedures; one is for the DELETE operation and the other for the TRUNCATE operation. Please note that for all practical purposes, the end result is the same – all data from the table TruncatePermissionsTest is removed Assigning the permissions Now comes the most important part of the demonstration – assigning permissions. A permissions matrix can be worked out as under: To apply the security rights, we use the GRANT and DENY clauses, as under: That’s it! We are now ready for our big test! THE TEST (01B_Truncate Table Test Queries.sql) Script Provided at the end of the article. I will now need two separate SSMS connections, one with the login AllowedTruncate and the other with the login RestrictedTruncate. Running the test is simple; all that’s required is to run through the script – 01B_Truncate Table Test Queries.sql. What I will demonstrate here via screen-shots is the behavior of SQL Server when logged in as the AllowedTruncate user. There are a few other combinations than what are highlighted here. I will leave the reader the right to explore the behavior of the RestrictedTruncate user and these additional scenarios, as a form of self-study. 1.       Testing SELECT permissions 2.       Testing TRUNCATE permissions (Remember, “deny by default”?) 3.       Trying to circumvent security by trying to TRUNCATE the table using the stored procedure Hence, we have now proved that a user can indeed be assigned permissions to specifically assign TRUNCATE permissions. I also hope that the above has sparked curiosity towards putting some security around the probably “destructive” operations of DELETE and TRUNCATE. I would like to wish each and every one of the readers a very happy and secure time with Microsoft SQL Server. (Please find the scripts – 01A_Truncate Table Permissions.sql and 01B_Truncate Table Test Queries.sql that have been used in this demonstration. Please note that these scripts contain purely test-level code only. These scripts must not, at any cost, be used in the reader’s production environments). 01A_Truncate Table Permissions.sql /* ***************************************************************************************************************** Developed By          : Nakul Vachhrajani Functionality         : This demo is focused on how to allow only TRUNCATE permissions to a particular user How to Use            : 1. Run through, step-by-step through the sequence till Step 08 to create a test database 2. Switch over to the "Truncate Table Test Queries.sql" and execute it step-by-step in two different SSMS windows, one where you have logged in as 'RestrictedTruncate', and the other as 'AllowedTruncate' 3. Come back to "Truncate Table Permissions.sql" 4. Execute Step 10 to cleanup! Modifications         : December 13, 2010 - NAV - Updated to add a security matrix and improve code readability when applying security December 12, 2010 - NAV - Created ***************************************************************************************************************** */ -- Step 01: Create a new test database CREATE DATABASE TruncateTestDB GO USE TruncateTestDB GO -- Step 02: Add roles and users to demonstrate the security of the Truncate operation -- 2a. Create the new roles CREATE ROLE AllowedTruncateRole; GO CREATE ROLE RestrictedTruncateRole; GO -- 2b. Create new logins CREATE LOGIN AllowedTruncate WITH PASSWORD = 'truncate@2010', CHECK_POLICY = ON GO CREATE LOGIN RestrictedTruncate WITH PASSWORD = 'truncate@2010', CHECK_POLICY = ON GO -- 2c. Create new Users using the roles and logins created aboave CREATE USER TruncateUser FOR LOGIN AllowedTruncate WITH DEFAULT_SCHEMA = dbo GO CREATE USER NoTruncateUser FOR LOGIN RestrictedTruncate WITH DEFAULT_SCHEMA = dbo GO -- 2d. Add the newly created login to the newly created role sp_addrolemember 'AllowedTruncateRole','TruncateUser' GO sp_addrolemember 'RestrictedTruncateRole','NoTruncateUser' GO -- Step 03: Change over to the test database USE TruncateTestDB GO -- Step 04: Create a test table within the test databse CREATE TABLE TruncatePermissionsTest (Id INT IDENTITY(1,1), Name NVARCHAR(50)) GO -- Step 05: Populate the required data INSERT INTO TruncatePermissionsTest VALUES (N'Delhi'), (N'Mumbai'), (N'Ahmedabad') GO -- Step 06: Encapsulate the DELETE within another module CREATE PROCEDURE proc_DeleteMyTable WITH EXECUTE AS SELF AS DELETE FROM TruncateTestDB..TruncatePermissionsTest GO -- Step 07: Encapsulate the TRUNCATE within another module CREATE PROCEDURE proc_TruncateMyTable WITH EXECUTE AS SELF AS TRUNCATE TABLE TruncateTestDB..TruncatePermissionsTest GO -- Step 08: Apply Security /* *****************************SECURITY MATRIX*************************************** =================================================================================== Object                   | Permissions |                 Login |             | AllowedTruncate   |   RestrictedTruncate |             |User:NoTruncateUser|   User:TruncateUser =================================================================================== TruncatePermissionsTest  | SELECT,     |      GRANT        |      (Default) | INSERT,     |                   | | UPDATE,     |                   | | DELETE      |                   | -------------------------+-------------+-------------------+----------------------- TruncatePermissionsTest  | ALTER       |      DENY         |      (Default) -------------------------+-------------+----*/----------------+----------------------- proc_DeleteMyTable | EXECUTE | GRANT | DENY -------------------------+-------------+-------------------+----------------------- proc_TruncateMyTable | EXECUTE | DENY | GRANT -------------------------+-------------+-------------------+----------------------- *****************************SECURITY MATRIX*************************************** */ /* Table: TruncatePermissionsTest*/ GRANT SELECT, INSERT, UPDATE, DELETE ON TruncateTestDB..TruncatePermissionsTest TO NoTruncateUser GO DENY ALTER ON TruncateTestDB..TruncatePermissionsTest TO NoTruncateUser GO /* Procedure: proc_DeleteMyTable*/ GRANT EXECUTE ON TruncateTestDB..proc_DeleteMyTable TO NoTruncateUser GO DENY EXECUTE ON TruncateTestDB..proc_DeleteMyTable TO TruncateUser GO /* Procedure: proc_TruncateMyTable*/ DENY EXECUTE ON TruncateTestDB..proc_TruncateMyTable TO NoTruncateUser GO GRANT EXECUTE ON TruncateTestDB..proc_TruncateMyTable TO TruncateUser GO -- Step 09: Test --Switch over to the "Truncate Table Test Queries.sql" and execute it step-by-step in two different SSMS windows: --    1. one where you have logged in as 'RestrictedTruncate', and --    2. the other as 'AllowedTruncate' -- Step 10: Cleanup sp_droprolemember 'AllowedTruncateRole','TruncateUser' GO sp_droprolemember 'RestrictedTruncateRole','NoTruncateUser' GO DROP USER TruncateUser GO DROP USER NoTruncateUser GO DROP LOGIN AllowedTruncate GO DROP LOGIN RestrictedTruncate GO DROP ROLE AllowedTruncateRole GO DROP ROLE RestrictedTruncateRole GO USE MASTER GO DROP DATABASE TruncateTestDB GO 01B_Truncate Table Test Queries.sql /* ***************************************************************************************************************** Developed By          : Nakul Vachhrajani Functionality         : This demo is focused on how to allow only TRUNCATE permissions to a particular user How to Use            : 1. Switch over to this from "Truncate Table Permissions.sql", Step #09 2. Execute this step-by-step in two different SSMS windows a. One where you have logged in as 'RestrictedTruncate', and b. The other as 'AllowedTruncate' 3. Return back to "Truncate Table Permissions.sql" 4. Execute Step 10 to cleanup! Modifications         : December 12, 2010 - NAV - Created ***************************************************************************************************************** */ -- Step 09A: Switch to the test database USE TruncateTestDB GO -- Step 09B: Ensure that we have valid data SELECT * FROM TruncatePermissionsTest GO -- (Expected: Following error will occur if logged in as "AllowedTruncate") -- Msg 229, Level 14, State 5, Line 1 -- The SELECT permission was denied on the object 'TruncatePermissionsTest', database 'TruncateTestDB', schema 'dbo'. --Step 09C: Attempt to Truncate Data from the table without using the stored procedure TRUNCATE TABLE TruncatePermissionsTest GO -- (Expected: Following error will occur) --  Msg 1088, Level 16, State 7, Line 2 --  Cannot find the object "TruncatePermissionsTest" because it does not exist or you do not have permissions. -- Step 09D:Regenerate Test Data INSERT INTO TruncatePermissionsTest VALUES (N'London'), (N'Paris'), (N'Berlin') GO -- (Expected: Following error will occur if logged in as "AllowedTruncate") -- Msg 229, Level 14, State 5, Line 1 -- The INSERT permission was denied on the object 'TruncatePermissionsTest', database 'TruncateTestDB', schema 'dbo'. --Step 09E: Attempt to Truncate Data from the table using the stored procedure EXEC proc_TruncateMyTable GO -- (Expected: Will execute successfully with 'AllowedTruncate' user, will error out as under with 'RestrictedTruncate') -- Msg 229, Level 14, State 5, Procedure proc_TruncateMyTable, Line 1 -- The EXECUTE permission was denied on the object 'proc_TruncateMyTable', database 'TruncateTestDB', schema 'dbo'. -- Step 09F:Regenerate Test Data INSERT INTO TruncatePermissionsTest VALUES (N'Madrid'), (N'Rome'), (N'Athens') GO --Step 09G: Attempt to Delete Data from the table without using the stored procedure DELETE FROM TruncatePermissionsTest GO -- (Expected: Following error will occur if logged in as "AllowedTruncate") -- Msg 229, Level 14, State 5, Line 2 -- The DELETE permission was denied on the object 'TruncatePermissionsTest', database 'TruncateTestDB', schema 'dbo'. -- Step 09H:Regenerate Test Data INSERT INTO TruncatePermissionsTest VALUES (N'Spain'), (N'Italy'), (N'Greece') GO --Step 09I: Attempt to Delete Data from the table using the stored procedure EXEC proc_DeleteMyTable GO -- (Expected: Following error will occur if logged in as "AllowedTruncate") -- Msg 229, Level 14, State 5, Procedure proc_DeleteMyTable, Line 1 -- The EXECUTE permission was denied on the object 'proc_DeleteMyTable', database 'TruncateTestDB', schema 'dbo'. --Step 09J: Close this SSMS window and return back to "Truncate Table Permissions.sql" Thank you Nakul to take up the challenge and prove that Ahmedabad and Gandhinagar SQL Server User Group has talent to solve difficult problems. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Best Practices, Pinal Dave, Readers Contribution, Readers Question, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Security, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• JMS Step 6 - How to Set Up an AQ JMS (Advanced Queueing JMS) for SOA Purposes

  - by John-Brown.Evans

  JMS Step 6 - How to Set Up an AQ JMS (Advanced Queueing JMS) for SOA Purposes .jblist{list-style-type:disc;margin:0;padding:0;padding-left:0pt;margin-left:36pt} ol{margin:0;padding:0} .c17_6{vertical-align:top;width:468pt;border-style:solid;border-color:#000000;border-width:1pt;padding:5pt 5pt 5pt 5pt} .c5_6{vertical-align:top;border-style:solid;border-color:#000000;border-width:1pt;padding:0pt 5pt 0pt 5pt} .c6_6{vertical-align:top;width:156pt;border-style:solid;border-color:#000000;border-width:1pt;padding:5pt 5pt 5pt 5pt} .c15_6{background-color:#ffffff} .c10_6{color:#1155cc;text-decoration:underline} .c1_6{text-align:center;direction:ltr} .c0_6{line-height:1.0;direction:ltr} .c16_6{color:#666666;font-size:12pt} .c18_6{color:inherit;text-decoration:inherit} .c8_6{background-color:#f3f3f3} .c2_6{direction:ltr} .c14_6{font-size:8pt} .c11_6{font-size:10pt} .c7_6{font-weight:bold} .c12_6{height:0pt} .c3_6{height:11pt} .c13_6{border-collapse:collapse} .c4_6{font-family:"Courier New"} .c9_6{font-style:italic} .title{padding-top:24pt;line-height:1.15;text-align:left;color:#000000;font-size:36pt;font-family:"Arial";font-weight:bold;padding-bottom:6pt} .subtitle{padding-top:18pt;line-height:1.15;text-align:left;color:#666666;font-style:italic;font-size:24pt;font-family:"Georgia";padding-bottom:4pt} li{color:#000000;font-size:10pt;font-family:"Arial"} p{color:#000000;font-size:10pt;margin:0;font-family:"Arial"} h1{padding-top:0pt;line-height:1.15;text-align:left;color:#888;font-size:24pt;font-family:"Arial";font-weight:normal} h2{padding-top:0pt;line-height:1.15;text-align:left;color:#888;font-size:18pt;font-family:"Arial";font-weight:normal} h3{padding-top:0pt;line-height:1.15;text-align:left;color:#888;font-size:14pt;font-family:"Arial";font-weight:normal} h4{padding-top:0pt;line-height:1.15;text-align:left;color:#888;font-size:12pt;font-family:"Arial";font-weight:normal} h5{padding-top:0pt;line-height:1.15;text-align:left;color:#888;font-size:11pt;font-family:"Arial";font-weight:normal} h6{padding-top:0pt;line-height:1.15;text-align:left;color:#888;font-size:10pt;font-family:"Arial";font-weight:normal} This post continues the series of JMS articles which demonstrate how to use JMS queues in a SOA context. The previous posts were: JMS Step 1 - How to Create a Simple JMS Queue in Weblogic Server 11g JMS Step 2 - Using the QueueSend.java Sample Program to Send a Message to a JMS Queue JMS Step 3 - Using the QueueReceive.java Sample Program to Read a Message from a JMS Queue JMS Step 4 - How to Create an 11g BPEL Process Which Writes a Message Based on an XML Schema to a JMS Queue JMS Step 5 - How to Create an 11g BPEL Process Which Reads a Message Based on an XML Schema from a JMS Queue This example leads you through the creation of an Oracle database Advanced Queue and the related WebLogic server objects in order to use AQ JMS in connection with a SOA composite. If you have not already done so, I recommend you look at the previous posts in this series, as they include steps which this example builds upon. The following examples will demonstrate how to write and read from the queue from a SOA process. 1. Recap and Prerequisites In the previous examples, we created a JMS Queue, a Connection Factory and a Connection Pool in the WebLogic Server Console. Then we wrote and deployed BPEL composites, which enqueued and dequeued a simple XML payload. AQ JMS allows you to interoperate with database Advanced Queueing via JMS in WebLogic server and therefore take advantage of database features, while maintaining compliance with the JMS architecture. AQ JMS uses the WebLogic JMS Foreign Server framework. A full description of this functionality can be found in the following Oracle documentation Oracle® Fusion Middleware Configuring and Managing JMS for Oracle WebLogic Server 11g Release 1 (10.3.6) Part Number E13738-06 7. Interoperating with Oracle AQ JMS http://docs.oracle.com/cd/E23943_01/web.1111/e13738/aq_jms.htm#CJACBCEJ For easier reference, this sample will use the same names for the objects as in the above document, except for the name of the database user, as it is possible that this user already exists in your database. We will create the following objects Database Objects Name Type AQJMSUSER Database User MyQueueTable Advanced Queue (AQ) Table UserQueue Advanced Queue WebLogic Server Objects Object Name Type JNDI Name aqjmsuserDataSource Data Source jdbc/aqjmsuserDataSource AqJmsModule JMS System Module AqJmsForeignServer JMS Foreign Server AqJmsForeignServerConnectionFactory JMS Foreign Server Connection Factory AqJmsForeignServerConnectionFactory AqJmsForeignDestination AQ JMS Foreign Destination queue/USERQUEUE eis/aqjms/UserQueue Connection Pool eis/aqjms/UserQueue 2. Create a Database User and Advanced Queue The following steps can be executed in the database client of your choice, e.g. JDeveloper or SQL Developer. The examples below use SQL*Plus. Log in to the database as a DBA user, for example SYSTEM or SYS. Create the AQJMSUSER user and grant privileges to enable the user to create AQ objects. Create Database User and Grant AQ Privileges sqlplus system/password as SYSDBA GRANT connect, resource TO aqjmsuser IDENTIFIED BY aqjmsuser; GRANT aq_user_role TO aqjmsuser; GRANT execute ON sys.dbms_aqadm TO aqjmsuser; GRANT execute ON sys.dbms_aq TO aqjmsuser; GRANT execute ON sys.dbms_aqin TO aqjmsuser; GRANT execute ON sys.dbms_aqjms TO aqjmsuser; Create the Queue Table and Advanced Queue and Start the AQ The following commands are executed as the aqjmsuser database user. Create the Queue Table connect aqjmsuser/aqjmsuser; BEGIN dbms_aqadm.create_queue_table ( queue_table = 'myQueueTable', queue_payload_type = 'sys.aq$_jms_text_message', multiple_consumers = false ); END; / Create the AQ BEGIN dbms_aqadm.create_queue ( queue_name = 'userQueue', queue_table = 'myQueueTable' ); END; / Start the AQ BEGIN dbms_aqadm.start_queue ( queue_name = 'userQueue'); END; / The above commands can be executed in a single PL/SQL block, but are shown as separate blocks in this example for ease of reference. You can verify the queue by executing the SQL command SELECT object_name, object_type FROM user_objects; which should display the following objects: OBJECT_NAME OBJECT_TYPE ------------------------------ ------------------- SYS_C0056513 INDEX SYS_LOB0000170822C00041$$ LOB SYS_LOB0000170822C00040$$ LOB SYS_LOB0000170822C00037$$ LOB AQ$_MYQUEUETABLE_T INDEX AQ$_MYQUEUETABLE_I INDEX AQ$_MYQUEUETABLE_E QUEUE AQ$_MYQUEUETABLE_F VIEW AQ$MYQUEUETABLE VIEW MYQUEUETABLE TABLE USERQUEUE QUEUE Similarly, you can view the objects in JDeveloper via a Database Connection to the AQJMSUSER. 3. Configure WebLogic Server and Add JMS Objects All these steps are executed from the WebLogic Server Administration Console. Log in as the webLogic user. Configure a WebLogic Data Source The data source is required for the database connection to the AQ created above. Navigate to domain > Services > Data Sources and press New then Generic Data Source. Use the values:Name: aqjmsuserDataSource JNDI Name: jdbc/aqjmsuserDataSource Database type: Oracle Database Driver: *Oracle’ Driver (Thin XA) for Instance connections; Versions:9.0.1 and later Connection Properties: Enter the connection information to the database containing the AQ created above and enter aqjmsuser for the User Name and Password. Press Test Configuration to verify the connection details and press Next. Target the data source to the soa server. The data source will be displayed in the list. It is a good idea to test the data source at this stage. Click on aqjmsuserDataSource, select Monitoring > Testing > soa_server1 and press Test Data Source. The result is displayed at the top of the page. Configure a JMS System Module The JMS system module is required to host the JMS foreign server for AQ resources. Navigate to Services > Messaging > JMS Modules and select New. Use the values: Name: AqJmsModule (Leave Descriptor File Name and Location in Domain empty.) Target: soa_server1 Click Finish. The other resources will be created in separate steps. The module will be displayed in the list.   Configure a JMS Foreign Server A foreign server is required in order to reference a 3rd-party JMS provider, in this case the database AQ, within a local WebLogic server JNDI tree. Navigate to Services > Messaging > JMS Modules and select (click on) AqJmsModule to configure it. Under Summary of Resources, select New then Foreign Server. Name: AqJmsForeignServer Targets: The foreign server is targeted automatically to soa_server1, based on the JMS module’s target. Press Finish to create the foreign server. The foreign server resource will be listed in the Summary of Resources for the AqJmsModule, but needs additional configuration steps. Click on AqJmsForeignServer and select Configuration > General to complete the configuration: JNDI Initial Context Factory: oracle.jms.AQjmsInitialContextFactory JNDI Connection URL: <empty> JNDI Properties Credential:<empty> Confirm JNDI Properties Credential: <empty> JNDI Properties: datasource=jdbc/aqjmsuserDataSource This is an important property. It is the JNDI name of the data source created above, which points to the AQ schema in the database and must be entered as a name=value pair, as in this example, e.g. datasource=jdbc/aqjmsuserDataSource, including the “datasource=” property name. Default Targeting Enabled: Leave this value checked. Press Save to save the configuration. At this point it is a good idea to verify that the data source was written correctly to the config file. In a terminal window, navigate to $MIDDLEWARE_HOME/user_projects/domains/soa_domain/config/jms  and open the file aqjmsmodule-jms.xml . The foreign server configuration should contain the datasource name-value pair, as follows:   <foreign-server name="AqJmsForeignServer">         <default-targeting-enabled>true</default-targeting-enabled>         <initial-context-factory>oracle.jms.AQjmsInitialContextFactory</initial-context-factory>         <jndi-property>           <key> datasource </key>           <value> jdbc/aqjmsuserDataSource </value>         </jndi-property>   </foreign-server> </weblogic-jms> Configure a JMS Foreign Server Connection Factory When creating the foreign server connection factory, you enter local and remote JNDI names. The name of the connection factory itself and the local JNDI name are arbitrary, but the remote JNDI name must match a specific format, depending on the type of queue or topic to be accessed in the database. This is very important and if the incorrect value is used, the connection to the queue will not be established and the error messages you get will not immediately reflect the cause of the error. The formats required (Remote JNDI names for AQ JMS Connection Factories) are described in the section Configure AQ Destinations  of the Oracle® Fusion Middleware Configuring and Managing JMS for Oracle WebLogic Server document mentioned earlier. In this example, the remote JNDI name used is   XAQueueConnectionFactory  because it matches the AQ and data source created earlier, i.e. thin with AQ. Navigate to JMS Modules > AqJmsModule > AqJmsForeignServer > Connection Factories then New.Name: AqJmsForeignServerConnectionFactory Local JNDI Name: AqJmsForeignServerConnectionFactory Note: this local JNDI name is the JNDI name which your client application, e.g. a later BPEL process, will use to access this connection factory. Remote JNDI Name: XAQueueConnectionFactory Press OK to save the configuration. Configure an AQ JMS Foreign Server Destination A foreign server destination maps the JNDI name on the foreign JNDI provider to the respective local JNDI name, allowing the foreign JNDI name to be accessed via the local server. As with the foreign server connection factory, the local JNDI name is arbitrary (but must be unique), but the remote JNDI name must conform to a specific format defined in the section Configure AQ Destinations  of the Oracle® Fusion Middleware Configuring and Managing JMS for Oracle WebLogic Server document mentioned earlier. In our example, the remote JNDI name is Queues/USERQUEUE , because it references a queue (as opposed to a topic) with the name USERQUEUE. We will name the local JNDI name queue/USERQUEUE, which is a little confusing (note the missing “s” in “queue), but conforms better to the JNDI nomenclature in our SOA server and also allows us to differentiate between the local and remote names for demonstration purposes. Navigate to JMS Modules > AqJmsModule > AqJmsForeignServer > Destinations and select New.Name: AqJmsForeignDestination Local JNDI Name: queue/USERQUEUE Remote JNDI Name:Queues/USERQUEUE After saving the foreign destination configuration, this completes the JMS part of the configuration. We still need to configure the JMS adapter in order to be able to access the queue from a BPEL processt. 4. Create a JMS Adapter Connection Pool in Weblogic Server Create the Connection Pool Access to the AQ JMS queue from a BPEL or other SOA process in our example is done via a JMS adapter. To enable this, the JmsAdapter in WebLogic server needs to be configured to have a connection pool which points to the local connection factory JNDI name which was created earlier. Navigate to Deployments > Next and select (click on) the JmsAdapter. Select Configuration > Outbound Connection Pools and New. Check the radio button for oracle.tip.adapter.jms.IJmsConnectionFactory and press Next. JNDI Name: eis/aqjms/UserQueue Press Finish Expand oracle.tip.adapter.jms.IJmsConnectionFactory and click on eis/aqjms/UserQueue to configure it. The ConnectionFactoryLocation must point to the foreign server’s local connection factory name created earlier. In our example, this is AqJmsForeignServerConnectionFactory . As a reminder, this connection factory is located under JMS Modules > AqJmsModule > AqJmsForeignServer > Connection Factories and the value needed here is under Local JNDI Name. Enter AqJmsForeignServerConnectionFactory  into the Property Value field for ConnectionFactoryLocation. You must then press Return/Enter then Save for the value to be accepted. If your WebLogic server is running in Development mode, you should see the message that the changes have been activated and the deployment plan successfully updated. If not, then you will manually need to activate the changes in the WebLogic server console.Although the changes have been activated, the JmsAdapter needs to be redeployed in order for the changes to become effective. This should be confirmed by the message Remember to update your deployment to reflect the new plan when you are finished with your changes. Redeploy the JmsAdapter Navigate back to the Deployments screen, either by selecting it in the left-hand navigation tree or by selecting the “Summary of Deployments” link in the breadcrumbs list at the top of the screen. Then select the checkbox next to JmsAdapter and press the Update button. On the Update Application Assistant page, select “Redeploy this application using the following deployment files” and press Finish. After a few seconds you should get the message that the selected deployments were updated. The JMS adapter configuration is complete and it can now be used to access the AQ JMS queue. You can verify that the JNDI name was created correctly, by navigating to Environment > Servers > soa_server1 and View JNDI Tree. Then scroll down in the JNDI Tree Structure to eis and select aqjms. This concludes the sample. In the following post, I will show you how to create a BPEL process which sends a message to this advanced queue via JMS. Best regards John-Brown Evans Oracle Technology Proactive Support Delivery

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• Design by Contract with Microsoft .Net Code Contract

  - by Fredrik N

  I have done some talks on different events and summits about Defensive Programming and Design by Contract, last time was at Cornerstone’s Developer Summit 2010. Next time will be at SweNug (Sweden .Net User Group). I decided to write a blog post about of some stuffs I was talking about. Users are a terrible thing! Protect your self from them ”Human users have a gift for doing the worst possible thing at the worst possible time.” – Michael T. Nygard, Release It! The kind of users Michael T. Nygard are talking about is the users of a system. We also have users that uses our code, the users I’m going to focus on is the users of our code. Me and you and another developers. “Any fool can write code that a computer can understand. Good programmers write code that humans can understand.” – Martin Fowler Good programmers also writes code that humans know how to use, good programmers also make sure software behave in a predictable manner despise inputs or user actions. Design by Contract   Design by Contract (DbC) is a way for us to make a contract between us (the code writer) and the users of our code. It’s about “If you give me this, I promise to give you this”. It’s not about business validations, that is something completely different that should be part of the domain model. DbC is to make sure the users of our code uses it in a correct way, and that we can rely on the contract and write code in a way where we know that the users will follow the contract. It will make it much easier for us to write code with a contract specified. Something like the following code is something we may see often: public void DoSomething(Object value) { value.DoIKnowThatICanDoThis(); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Where “value” can be uses directly or passed to other methods and later be used. What some of us can easily forget here is that the “value” can be “null”. We will probably not passing a null value, but someone else that uses our code maybe will do it. I think most of you (including me) have passed “null” into a method because you don’t know if the argument need to be specified to a valid value etc. I bet most of you also have got the “Null reference exception”. Sometimes this “Null reference exception” can be hard and take time to fix, because we need to search among our code to see where the “null” value was passed in etc. Wouldn’t it be much better if we can as early as possible specify that the value can’t not be null, so the users of our code also know it when the users starts to use our code, and before run time execution of the code? This is where DbC comes into the picture. We can use DbC to specify what we need, and by doing so we can rely on the contract when we write our code. So the code above can actually use the DoIKnowThatICanDoThis() method on the value object without being worried that the “value” can be null. The contract between the users of the code and us writing the code, says that the “value” can’t be null.   Pre- and Postconditions   When working with DbC we are specifying pre- and postconditions.  Precondition is a condition that should be met before a query or command is executed. An example of a precondition is: “The Value argument of the method can’t be null”, and we make sure the “value” isn’t null before the method is called. Postcondition is a condition that should be met when a command or query is completed, a postcondition will make sure the result is correct. An example of a postconditon is “The method will return a list with at least 1 item”. Commands an Quires When using DbC, we need to know what a Command and a Query is, because some principles that can be good to follow are based on commands and queries. A Command is something that will not return anything, like the SQL’s CREATE, UPDATE and DELETE. There are two kinds of Commands when using DbC, the Creation commands (for example a Constructor), and Others. Others can for example be a Command to add a value to a list, remove or update a value etc. //Creation commands public Stack(int size) //Other commands public void Push(object value); public void Remove(); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   A Query, is something that will return something, for example an Attribute, Property or a Function, like the SQL’s SELECT.   There are two kinds of Queries, the Basic Queries  (Quires that aren’t based on another queries), and the Derived Queries, queries that is based on another queries. Here is an example of queries of a Stack: //Basic Queries public int Count; public object this[int index] { get; } //Derived Queries //Is related to Count Query public bool IsEmpty() { return Count == 0; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } To understand about some principles that are good to follow when using DbC, we need to know about the Commands and different Queries. The 6 Principles When working with DbC, it’s advisable to follow some principles to make it easier to define and use contracts. The following DbC principles are: Separate commands and queries. Separate basic queries from derived queries. For each derived query, write a postcondition that specifies what result will be returned, in terms of one or more basic queries. For each command, write a postcondition that specifies the value of every basic query. For every query and command, decide on a suitable precondition. Write invariants to define unchanging properties of objects. Before I will write about each of them I want you to now that I’m going to use .Net 4.0 Code Contract. I will in the rest of the post uses a simple Stack (Yes I know, .Net already have a Stack class) to give you the basic understanding about using DbC. A Stack is a data structure where the first item in, will be the first item out. Here is a basic implementation of a Stack where not contract is specified yet: public class Stack { private object[] _array; //Basic Queries public uint Count; public object this[uint index] { get { return _array[index]; } set { _array[index] = value; } } //Derived Queries //Is related to Count Query public bool IsEmpty() { return Count == 0; } //Is related to Count and this[] Query public object Top() { return this[Count]; } //Creation commands public Stack(uint size) { Count = 0; _array = new object[size]; } //Other commands public void Push(object value) { this[++Count] = value; } public void Remove() { this[Count] = null; Count--; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Note: The Stack is implemented in a way to demonstrate the use of Code Contract in a simple way, the implementation may not look like how you would implement it, so don’t think this is the perfect Stack implementation, only used for demonstration.   Before I will go deeper into the principles I will simply mention how we can use the .Net Code Contract. I mention before about pre- and postcondition, is about “Require” something and to “Ensure” something. When using Code Contract, we will use a static class called “Contract” and is located in he “System.Diagnostics.Contracts” namespace. The contract must be specified at the top or our member statement block. To specify a precondition with Code Contract we uses the Contract.Requires method, and to specify a postcondition, we uses the Contract.Ensure method. Here is an example where both a pre- and postcondition are used: public object Top() { Contract.Requires(Count > 0, "Stack is empty"); Contract.Ensures(Contract.Result<object>() == this[Count]); return this[Count]; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The contract above requires that the Count is greater than 0, if not we can’t get the item at the Top of a Stack. We also Ensures that the results (By using the Contract.Result method, we can specify a postcondition that will check if the value returned from a method is correct) of the Top query is equal to this[Count].   1. Separate Commands and Queries   When working with DbC, it’s important to separate Command and Quires. A method should either be a command that performs an Action, or returning information to the caller, not both. By asking a question the answer shouldn’t be changed. The following is an example of a Command and a Query of a Stack: public void Push(object value) public object Top() .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The Push is a command and will not return anything, just add a value to the Stack, the Top is a query to get the item at the top of the stack.   2. Separate basic queries from derived queries There are two different kinds of queries,  the basic queries that doesn’t rely on another queries, and derived queries that uses a basic query. The “Separate basic queries from derived queries” principle is about about that derived queries can be specified in terms of basic queries. So this principles is more about recognizing that a query is a derived query or a basic query. It will then make is much easier to follow the other principles. The following code shows a basic query and a derived query: //Basic Queries public uint Count; //Derived Queries //Is related to Count Query public bool IsEmpty() { return Count == 0; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   We can see that IsEmpty will use the Count query, and that makes the IsEmpty a Derived query.   3. For each derived query, write a postcondition that specifies what result will be returned, in terms of one or more basic queries.   When the derived query is recognize we can follow the 3ed principle. For each derived query, we can create a postcondition that specifies what result our derived query will return in terms of one or more basic queries. Remember that DbC is about contracts between the users of the code and us writing the code. So we can’t use demand that the users will pass in a valid value, we must also ensure that we will give the users what the users wants, when the user is following our contract. The IsEmpty query of the Stack will use a Count query and that will make the IsEmpty a Derived query, so we should now write a postcondition that specified what results will be returned, in terms of using a basic query and in this case the Count query, //Basic Queries public uint Count; //Derived Queries public bool IsEmpty() { Contract.Ensures(Contract.Result<bool>() == (Count == 0)); return Count == 0; } The Contract.Ensures is used to create a postcondition. The above code will make sure that the results of the IsEmpty (by using the Contract.Result to get the result of the IsEmpty method) is correct, that will say that the IsEmpty will be either true or false based on Count is equal to 0 or not. The postcondition are using a basic query, so the IsEmpty is now following the 3ed principle. We also have another Derived Query, the Top query, it will also need a postcondition and it uses all basic queries. The Result of the Top method must be the same value as the this[] query returns. //Basic Queries public uint Count; public object this[uint index] { get { return _array[index]; } set { _array[index] = value; } } //Derived Queries //Is related to Count and this[] Query public object Top() { Contract.Ensures(Contract.Result<object>() == this[Count]); return this[Count]; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   4. For each command, write a postcondition that specifies the value of every basic query.   For each command we will create a postconditon that specifies the value of basic queries. If we look at the Stack implementation we will have three Commands, one Creation command, the Constructor, and two others commands, Push and Remove. Those commands need a postcondition and they should include basic query to follow the 4th principle. //Creation commands public Stack(uint size) { Contract.Ensures(Count == 0); Count = 0; _array = new object[size]; } //Other commands public void Push(object value) { Contract.Ensures(Count == Contract.OldValue<uint>(Count) + 1); Contract.Ensures(this[Count] == value); this[++Count] = value; } public void Remove() { Contract.Ensures(Count == Contract.OldValue<uint>(Count) - 1); this[Count] = null; Count--; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   As you can see the Create command will Ensures that Count will be 0 when the Stack is created, when a Stack is created there shouldn’t be any items in the stack. The Push command will take a value and put it into the Stack, when an item is pushed into the Stack, the Count need to be increased to know the number of items added to the Stack, and we must also make sure the item is really added to the Stack. The postconditon of the Push method will make sure the that old value of the Count (by using the Contract.OldValue we can get the value a Query has before the method is called)  plus 1 will be equal to the Count query, this is the way we can ensure that the Push will increase the Count with one. We also make sure the this[] query will now contain the item we pushed into the Stack. The Remove method must make sure the Count is decreased by one when the top item is removed from the Stack. The Commands is now following the 4th principle, where each command now have a postcondition that used the value of basic queries. Note: The principle says every basic Query, the Remove only used one Query the Count, it’s because this command can’t use the this[] query because an item is removed, so the only way to make sure an item is removed is to just use the Count query, so the Remove will still follow the principle.   5. For every query and command, decide on a suitable precondition.   We have now focused only on postcondition, now time for some preconditons. The 5th principle is about deciding a suitable preconditon for every query and command. If we starts to look at one of our basic queries (will not go through all Queries and commands here, just some of them) the this[] query, we can’t pass an index that is lower then 1 (.Net arrays and list are zero based, but not the stack in this blog post ;)) and the index can’t be lesser than the number of items in the stack. So here we will need a preconditon. public object this[uint index] { get { Contract.Requires(index >= 1); Contract.Requires(index <= Count); return _array[index]; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Think about the Contract as an documentation about how to use the code in a correct way, so if the contract could be specified elsewhere (not part of the method body), we could simply write “return _array[index]” and there is no need to check if index is greater or lesser than Count, because that is specified in a “contract”. The implementation of Code Contract, requires that the contract is specified in the code. As a developer I would rather have this contract elsewhere (Like Spec#) or implemented in a way Eiffel uses it as part of the language. Now when we have looked at one Query, we can also look at one command, the Remove command (You can see the whole implementation of the Stack at the end of this blog post, where precondition is added to more queries and commands then what I’m going to show in this section). We can only Remove an item if the Count is greater than 0. So we can write a precondition that will require that Count must be greater than 0. public void Remove() { Contract.Requires(Count > 0); Contract.Ensures(Count == Contract.OldValue<uint>(Count) - 1); this[Count] = null; Count--; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   6. Write invariants to define unchanging properties of objects.   The last principle is about making sure the object are feeling great! This is done by using invariants. When using Code Contract we can specify invariants by adding a method with the attribute ContractInvariantMethod, the method must be private or public and can only contains calls to Contract.Invariant. To make sure the Stack feels great, the Stack must have 0 or more items, the Count can’t never be a negative value to make sure each command and queries can be used of the Stack. Here is our invariant for the Stack object: [ContractInvariantMethod] private void ObjectInvariant() { Contract.Invariant(Count >= 0); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Note: The ObjectInvariant method will be called every time after a Query or Commands is called. Here is the full example using Code Contract:   public class Stack { private object[] _array; //Basic Queries public uint Count; public object this[uint index] { get { Contract.Requires(index >= 1); Contract.Requires(index <= Count); return _array[index]; } set { Contract.Requires(index >= 1); Contract.Requires(index <= Count); _array[index] = value; } } //Derived Queries //Is related to Count Query public bool IsEmpty() { Contract.Ensures(Contract.Result<bool>() == (Count == 0)); return Count == 0; } //Is related to Count and this[] Query public object Top() { Contract.Requires(Count > 0, "Stack is empty"); Contract.Ensures(Contract.Result<object>() == this[Count]); return this[Count]; } //Creation commands public Stack(uint size) { Contract.Requires(size > 0); Contract.Ensures(Count == 0); Count = 0; _array = new object[size]; } //Other commands public void Push(object value) { Contract.Requires(value != null); Contract.Ensures(Count == Contract.OldValue<uint>(Count) + 1); Contract.Ensures(this[Count] == value); this[++Count] = value; } public void Remove() { Contract.Requires(Count > 0); Contract.Ensures(Count == Contract.OldValue<uint>(Count) - 1); this[Count] = null; Count--; } [ContractInvariantMethod] private void ObjectInvariant() { Contract.Invariant(Count >= 0); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Summary By using Design By Contract we can make sure the users are using our code in a correct way, and we must also make sure the users will get the expected results when they uses our code. This can be done by specifying contracts. To make it easy to use Design By Contract, some principles may be good to follow like the separation of commands an queries. With .Net 4.0 we can use the Code Contract feature to specify contracts.

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• Testing Entity Framework applications, pt. 3: NDbUnit

  - by Thomas Weller

  This is the third of a three part series that deals with the issue of faking test data in the context of a legacy app that was built with Microsoft's Entity Framework (EF) on top of an MS SQL Server database – a scenario that can be found very often. Please read the first part for a description of the sample application, a discussion of some general aspects of unit testing in a database context, and of some more specific aspects of the here discussed EF/MSSQL combination. Lately, I wondered how you would ‘mock’ the data layer of a legacy application, when this data layer is made up of an MS Entity Framework (EF) model in combination with a MS SQL Server database. Originally, this question came up in the context of how you could enable higher-level integration tests (automated UI tests, to be exact) for a legacy application that uses this EF/MSSQL combo as its data store mechanism – a not so uncommon scenario. The question sparked my interest, and I decided to dive into it somewhat deeper. What I've found out is, in short, that it's not very easy and straightforward to do it – but it can be done. The two strategies that are best suited to fit the bill involve using either the (commercial) Typemock Isolator tool or the (free) NDbUnit framework. The use of Typemock was discussed in the previous post, this post now will present the NDbUnit approach... NDbUnit is an Apache 2.0-licensed open-source project, and like so many other Nxxx tools and frameworks, it is basically a C#/.NET port of the corresponding Java version (DbUnit namely). In short, it helps you in flexibly managing the state of a database in that it lets you easily perform basic operations (like e.g. Insert, Delete, Refresh, DeleteAll)  against your database and, most notably, lets you feed it with data from external xml files. Let's have a look at how things can be done with the help of this framework. Preparing the test data Compared to Typemock, using NDbUnit implies a totally different approach to meet our testing needs.  So the here described testing scenario requires an instance of an SQL Server database in operation, and it also means that the Entity Framework model that sits on top of this database is completely unaffected. First things first: For its interactions with the database, NDbUnit relies on a .NET Dataset xsd file. See Step 1 of their Quick Start Guide for a description of how to create one. With this prerequisite in place then, the test fixture's setup code could look something like this: [TestFixture, TestsOn(typeof(PersonRepository))] [Metadata("NDbUnit Quickstart URL",           "http://code.google.com/p/ndbunit/wiki/QuickStartGuide")] [Description("Uses the NDbUnit library to provide test data to a local database.")] public class PersonRepositoryFixture {     #region Constants     private const string XmlSchema = @"..\..\TestData\School.xsd";     #endregion // Constants     #region Fields     private SchoolEntities _schoolContext;     private PersonRepository _personRepository;     private INDbUnitTest _database;     #endregion // Fields     #region Setup/TearDown     [FixtureSetUp]     public void FixtureSetUp()     {         var connectionString = ConfigurationManager.ConnectionStrings["School_Test"].ConnectionString;         _database = new SqlDbUnitTest(connectionString);         _database.ReadXmlSchema(XmlSchema);         var entityConnectionStringBuilder = new EntityConnectionStringBuilder         {             Metadata = "res://*/School.csdl|res://*/School.ssdl|res://*/School.msl",             Provider = "System.Data.SqlClient",             ProviderConnectionString = connectionString         };         _schoolContext = new SchoolEntities(entityConnectionStringBuilder.ConnectionString);         _personRepository = new PersonRepository(this._schoolContext);     }     [FixtureTearDown]     public void FixtureTearDown()     {         _database.PerformDbOperation(DbOperationFlag.DeleteAll);         _schoolContext.Dispose();     }     ...  As you can see, there is slightly more fixture setup code involved if your tests are using NDbUnit to provide the test data: Because we're dealing with a physical database instance here, we first need to pick up the test-specific connection string from the test assemblies' App.config, then initialize an NDbUnit helper object with this connection along with the provided xsd file, and also set up the SchoolEntities and the PersonRepository instances accordingly. The _database field (an instance of the INdUnitTest interface) will be our single access point to the underlying database: We use it to perform all the required operations against the data store. To have a flexible mechanism to easily insert data into the database, we can write a helper method like this: private void InsertTestData(params string[] dataFileNames) {     _database.PerformDbOperation(DbOperationFlag.DeleteAll);     if (dataFileNames == null)     {         return;     }     try     {         foreach (string fileName in dataFileNames)         {             if (!File.Exists(fileName))             {                 throw new FileNotFoundException(Path.GetFullPath(fileName));             }             _database.ReadXml(fileName);             _database.PerformDbOperation(DbOperationFlag.InsertIdentity);         }     }     catch     {         _database.PerformDbOperation(DbOperationFlag.DeleteAll);         throw;     } } This lets us easily insert test data from xml files, in any number and in a  controlled order (which is important because we eventually must fulfill referential constraints, or we must account for some other stuff that imposes a specific ordering on data insertion). Again, as with Typemock, I won't go into API details here. - Unfortunately, there isn't too much documentation for NDbUnit anyway, other than the already mentioned Quick Start Guide (and the source code itself, of course) - a not so uncommon problem with smaller Open Source Projects. Last not least, we need to provide the required test data in xml form. A snippet for data from the People table might look like this, for example: <?xml version="1.0" encoding="utf-8" ?> <School xmlns="http://tempuri.org/School.xsd">   <Person>     <PersonID>1</PersonID>     <LastName>Abercrombie</LastName>     <FirstName>Kim</FirstName>     <HireDate>1995-03-11T00:00:00</HireDate>   </Person>   <Person>     <PersonID>2</PersonID>     <LastName>Barzdukas</LastName>     <FirstName>Gytis</FirstName>     <EnrollmentDate>2005-09-01T00:00:00</EnrollmentDate>   </Person>   <Person>     ... You can also have data from various tables in one single xml file, if that's appropriate for you (but beware of the already mentioned ordering issues). It's true that your test assembly may end up with dozens of such xml files, each containing quite a big amount of text data. But because the files are of very low complexity, and with the help of a little bit of Copy/Paste and Excel magic, this appears to be well manageable. Executing some basic tests Here are some of the possible tests that can be written with the above preparations in place: private const string People = @"..\..\TestData\School.People.xml"; ... [Test, MultipleAsserts, TestsOn("PersonRepository.GetNameList")] public void GetNameList_ListOrdering_ReturnsTheExpectedFullNames() {     InsertTestData(People);     List<string> names =         _personRepository.GetNameList(NameOrdering.List);     Assert.Count(34, names);     Assert.AreEqual("Abercrombie, Kim", names.First());     Assert.AreEqual("Zheng, Roger", names.Last()); } [Test, MultipleAsserts, TestsOn("PersonRepository.GetNameList")] [DependsOn("RemovePerson_CalledOnce_DecreasesCountByOne")] public void GetNameList_NormalOrdering_ReturnsTheExpectedFullNames() {     InsertTestData(People);     List<string> names =         _personRepository.GetNameList(NameOrdering.Normal);     Assert.Count(34, names);     Assert.AreEqual("Alexandra Walker", names.First());     Assert.AreEqual("Yan Li", names.Last()); } [Test, TestsOn("PersonRepository.AddPerson")] public void AddPerson_CalledOnce_IncreasesCountByOne() {     InsertTestData(People);     int count = _personRepository.Count;     _personRepository.AddPerson(new Person { FirstName = "Thomas", LastName = "Weller" });     Assert.AreEqual(count + 1, _personRepository.Count); } [Test, TestsOn("PersonRepository.RemovePerson")] public void RemovePerson_CalledOnce_DecreasesCountByOne() {     InsertTestData(People);     int count = _personRepository.Count;     _personRepository.RemovePerson(new Person { PersonID = 33 });     Assert.AreEqual(count - 1, _personRepository.Count); } Not much difference here compared to the corresponding Typemock versions, except that we had to do a bit more preparational work (and also it was harder to get the required knowledge). But this picture changes quite dramatically if we look at some more demanding test cases: Ok, and what if things are becoming somewhat more complex? Tests like the above ones represent the 'easy' scenarios. They may account for the biggest portion of real-world use cases of the application, and they are important to make sure that it is generally sound. But usually, all these nasty little bugs originate from the more complex parts of our code, or they occur when something goes wrong. So, for a testing strategy to be of real practical use, it is especially important to see how easy or difficult it is to mimick a scenario which represents a more complex or exceptional case. The following test, for example, deals with the case that there is some sort of invalid input from the caller: [Test, MultipleAsserts, TestsOn("PersonRepository.GetCourseMembers")] [Row(null, typeof(ArgumentNullException))] [Row("", typeof(ArgumentException))] [Row("NotExistingCourse", typeof(ArgumentException))] public void GetCourseMembers_WithGivenVariousInvalidValues_Throws(string courseTitle, Type expectedInnerExceptionType) {     var exception = Assert.Throws<RepositoryException>(() =>                                 _personRepository.GetCourseMembers(courseTitle));     Assert.IsInstanceOfType(expectedInnerExceptionType, exception.InnerException); } Apparently, this test doesn't need an 'Arrange' part at all (see here for the same test with the Typemock tool). It acts just like any other client code, and all the required business logic comes from the database itself. This doesn't always necessarily mean that there is less complexity, but only that the complexity happens in a different part of your test resources (in the xml files namely, where you sometimes have to spend a lot of effort for carefully preparing the required test data). Another example, which relies on an underlying 1-n relationship, might be this: [Test, MultipleAsserts, TestsOn("PersonRepository.GetCourseMembers")] public void GetCourseMembers_WhenGivenAnExistingCourse_ReturnsListOfStudents() {     InsertTestData(People, Course, Department, StudentGrade);     List<Person> persons = _personRepository.GetCourseMembers("Macroeconomics");     Assert.Count(4, persons);     Assert.ForAll(         persons,         @p => new[] { 10, 11, 12, 14 }.Contains(@p.PersonID),         "Person has none of the expected IDs."); } If you compare this test to its corresponding Typemock version, you immediately see that the test itself is much simpler, easier to read, and thus much more intention-revealing. The complexity here lies hidden behind the call to the InsertTestData() helper method and the content of the used xml files with the test data. And also note that you might have to provide additional data which are not even directly relevant to your test, but are required only to fulfill some integrity needs of the underlying database. Conclusion The first thing to notice when comparing the NDbUnit approach to its Typemock counterpart obviously deals with performance: Of course, NDbUnit is much slower than Typemock. Technically,  it doesn't even make sense to compare the two tools. But practically, it may well play a role and could or could not be an issue, depending on how much tests you have of this kind, how often you run them, and what role they play in your development cycle. Also, because the dataset from the required xsd file must fully match the database schema (even in parts that otherwise wouldn't be relevant to you), it can be quite cumbersome to be in a team where different people are working with the database in parallel. My personal experience is – as already said in the first part – that Typemock gives you a better development experience in a 'dynamic' scenario (when you're working in some kind of TDD-style, you're oftentimes executing the tests from your dev box, and your database schema changes frequently), whereas the NDbUnit approach is a good and solid solution in more 'static' development scenarios (when you need to execute the tests less frequently or only on a separate build server, and/or the underlying database schema can be kept relatively stable), for example some variations of higher-level integration or User-Acceptance tests. But in any case, opening Entity Framework based applications for testing requires a fair amount of resources, planning, and preparational work – it's definitely not the kind of stuff that you would call 'easy to test'. Hopefully, future versions of EF will take testing concerns into account. Otherwise, I don't see too much of a future for the framework in the long run, even though it's quite popular at the moment... The sample solution A sample solution (VS 2010) with the code from this article series is available via my Bitbucket account from here (Bitbucket is a hosting site for Mercurial repositories. The repositories may also be accessed with the Git and Subversion SCMs - consult the documentation for details. In addition, it is possible to download the solution simply as a zipped archive – via the 'get source' button on the very right.). The solution contains some more tests against the PersonRepository class, which are not shown here. Also, it contains database scripts to create and fill the School sample database. To compile and run, the solution expects the Gallio/MbUnit framework to be installed (which is free and can be downloaded from here), the NDbUnit framework (which is also free and can be downloaded from here), and the Typemock Isolator tool (a fully functional 30day-trial is available here). Moreover, you will need an instance of the Microsoft SQL Server DBMS, and you will have to adapt the connection strings in the test projects App.config files accordingly.

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• Entity Framework 4.3.1 Code based Migrations and Connector/Net 6.6

  - by GABMARTINEZ

   Code-based migrations is a new feature as part of the Connector/Net support for Entity Framework 4.3.1. In this tutorial we'll see how we can use it so we can keep track of the changes done to our database creating a new application using the code first approach. If you don't have a clear idea about how code first works we highly recommend you to check this subject before going further with this tutorial. Creating our Model and Database with Code First  From VS 2010  1. Create a new console application 2.  Add the latest Entity Framework official package using Package Manager Console (Tools Menu, then Library Package Manager -> Package Manager Console). In the Package Manager Console we have to type  Install-Package EntityFramework This will add the latest version of this library.  We will also need to make some changes to your config file. A <configSections> was added which contains the version you have from EntityFramework.  An <entityFramework> section was also added where you can set up some initialization. This section is optional and by default is generated to use SQL Express. Since we don't need it for now (we'll see more about it below) let's leave this section empty as shown below. 3. Create a new Model with a simple entity. 4. Enable Migrations to generate the our Configuration class. In the Package Manager Console we have to type  Enable-Migrations; This will make some changes in our application. It will create a new folder called Migrations where all the migrations representing the changes we do to our model.  It will also create a Configuration class that we'll be using to initialize our SQL Generator and some other values like if we want to enable Automatic Migrations.  You can see that it already has the name of our DbContext. You can also create you Configuration class manually. 5. Specify our Model Provider. We need to specify in our Class Configuration that we'll be using MySQLClient since this is not part of the generated code. Also please make sure you have added the MySql.Data and the MySql.Data.Entity references to your project. using MySql.Data.Entity;   // Add the MySQL.Data.Entity namespace public Configuration() { this.AutomaticMigrationsEnabled = false; SetSqlGenerator("MySql.Data.MySqlClient", new MySql.Data.Entity.MySqlMigrationSqlGenerator());    // This will add our MySQLClient as SQL Generator } 6. Add our Data Provider and set up our connection string <connectionStrings> <add name="PersonalContext" connectionString="server=localhost;User Id=root;database=Personal;" providerName="MySql.Data.MySqlClient" /> </connectionStrings> <system.data> <DbProviderFactories> <remove invariant="MySql.Data.MySqlClient" /> <add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient" description=".Net Framework Data Provider for MySQL" type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data, Version=6.6.2.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d" /> </DbProviderFactories> </system.data> * The version recommended to use of Connector/Net is 6.6.2 or earlier. At this point we can create our database and then start working with Migrations. So let's do some data access so our database get's created. You can run your application and you'll get your database Personal as specified in our config file. Add our first migration Migrations are a great resource as we can have a record for all the changes done and will generate the MySQL statements required to apply these changes to the database. Let's add a new property to our Person class public string Email { get; set; } If you try to run your application it will throw an exception saying  The model backing the 'PersonelContext' context has changed since the database was created. Consider using Code First Migrations to update the database (http://go.microsoft.com/fwlink/?LinkId=238269). So as suggested let's add our first migration for this change. In the Package Manager Console let's type Add-Migration AddEmailColumn Now we have the corresponding class which generate the necessary operations to update our database. namespace MigrationsFromScratch.Migrations { using System.Data.Entity.Migrations; public partial class AddEmailColumn : DbMigration { public override void Up(){ AddColumn("People", "Email", c => c.String(unicode: false)); } public override void Down() { DropColumn("People", "Email"); } } } In the Package Manager Console let's type Update-Database Now you can check your database to see all changes were succesfully applied. Now let's add a second change and generate our second migration public class Person   {       [Key]       public int PersonId { get; set;}       public string Name { get; set; }       public string Address {get; set;}       public string Email { get; set; }       public List<Skill> Skills { get; set; }   }   public class Skill   {     [Key]     public int SkillId { get; set; }     public string Description { get; set; }   }   public class PersonelContext : DbContext   {     public DbSet<Person> Persons { get; set; }     public DbSet<Skill> Skills { get; set; }   } If you would like to customize any part of this code you can do that at this step. You can see there is the up method which can update your database and the down that can revert the changes done. If you customize any code you should make sure to customize in both methods. Now let's apply this change. Update-database -verbose I added the verbose flag so you can see all the SQL generated statements to be run. Downgrading changes So far we have always upgraded to the latest migration, but there may be times when you want downgrade to a specific migration. Let's say we want to return to the status we have before our last migration. We can use the -TargetMigration option to specify the migration we'd like to return. Also you can use the -verbose flag. If you like to go  back to the Initial state you can do: Update-Database -TargetMigration:$InitialDatabase  or equivalent: Update-Database -TargetMigration:0  Migrations doesn't allow by default a migration that would ocurr in a data loss. One case when you can got this message is for example in a DropColumn operation. You can override this configuration by setting AutomaticMigrationDataLossAllowed to true in the configuration class. Also you can set your Database Initializer in case you want that these Migrations can be applied automatically and you don't have to go all the way through creating a migration and updating later the changes. Let's see how. Database Initialization by Code We can specify an initialization strategy by using Database.SetInitializer (http://msdn.microsoft.com/en-us/library/gg679461(v=vs.103)). One of the strategies that I found very useful when you are at a development stage (I mean not for production) is the MigrateDatabaseToLatestVersion. This strategy will make all the necessary migrations each time there is a change in our model that needs a database replication, this also implies that we have to enable AutomaticMigrationsEnabled flag in our Configuration class. public Configuration()         {             AutomaticMigrationsEnabled = true;             AutomaticMigrationDataLossAllowed = true;             SetSqlGenerator("MySql.Data.MySqlClient", new MySql.Data.Entity.MySqlMigrationSqlGenerator());    // This will add our MySQLClient as SQL Generator          } In the new EntityFramework section of your Config file we can set this at a context level basis.  The syntax is as follows: <contexts> <context type="Custom DbContext name, Assembly name"> <databaseInitializer type="System.Data.Entity.MigrateDatabaseToLatestVersion`2[[ Custom DbContext name, Assembly name],  [Configuration class name, Assembly name]],  EntityFramework" /> </context> </contexts> In our example this would be: The syntax is kind of odd but very convenient. This way all changes will always be applied when we do any data access in our application. There are a lot of new things to explore in EF 4.3.1 and Migrations so we'll continue writing some more posts about it. Please let us know if you have any questions or comments, also please check our forums here where we keep answering questions in general for the community.  Hope you found this information useful. Happy MySQL/.Net Coding! 

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• Can a database function be called in the predicate of a llblgen query?

  - by Dan Appleyard

  I want to use a table-valued database function in the where clause of a query I am building using LLBLGen Pro 2.6 (self-servicing). SELECT * FROM [dbo].[Users] WHERE [dbo].[Users].[UserID] IN ( SELECT UserID FROM [dbo].[GetScopedUsers] (@ScopedUserID) ) I am looking into the FieldCompareSetPredicate class, but can't for the life of me figure out what the exact signature would be. Any help would be greatly appreciated.

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• Suggest an alternative way to organize/build a database solution.

  - by Hamish Grubijan

  We are using Visual Studio 2010, but this was first conceived with VS2003. I will forward the best suggestions to my team. The current setup almost makes me vomit. It is a C# solution with most projects containing .sql files. Because we support Microsoft, Oracle, and Sybase, and so home-brewed a pre-processor, much like C preprocessor, except that substitutions are performed by a home-brewed C# program without using yacc and tools like that. #ifdefs are used for conditional macro definitions, and yeah - macros are the way this is done. A macro can expand to another macro or two, but this should eventually terminate. Only macros have #ifdef in them - the rest of the SQL-like code just uses these macros. Now, the various configurations: Debug, MNDebug, MNRelease, Release, SQL_APPLY_ALL, SQL_APPLY_MSFT, SQL_APPLY_ORACLE, SQL_APPLY_SYBASE, SQL_BUILD_OUTPUT_ALL, SQL_COMPILE, as well as 2 more. Also: Any CPU, Mixed Platforms, Win32. What drives me nuts is having to configure it correctly as well as choosing the right one out of 12 x 3 = 36 configurations as well as having to substitute database name depending on the type of database: config, main, or gateway. I am thinking that configuration should be reduced to just Debug, Release, and SQL_APPLY. Also, using 0, 1, and 2 seems so 80s ... Finally, I think my intention to build or not to build 3 types of databases for 3 types of vendors should be configured with just a tic tac toe board like: XOX OOX XXX In this case it would mean build MSFT+CONFIG, all SYBASE, and all GATEWAY. Still, the overall thing which uses a text file and a pre-processor and many configurations seems incredibly clunky. It is year 2010 now and someone out there is bound to have a very clean and/or creative tool/solution. The only pro would be that the existing collection of macros has been well tested. Have you ever had to write SQL that would work for several vendors? How did you do it? SqlVars.txt (Every one of 30 users makes a copy of a template and modifies this to suit their needs): // This is the default parameters file and should not be changed. // You can overwrite any of these parameters by copying the appropriate // section to override into SqlVars.txt and providing your own information. //Build types are 0-Config, 1-Main, 2-Gateway BUILD_TYPE=1 REMOVE_COMMENTS=1 // Login information used when applying to a Microsoft SQL server database SQL_APPLY_MSFT_version=SQL2005 SQL_APPLY_MSFT_database=msftdb SQL_APPLY_MSFT_server=ABC SQL_APPLY_MSFT_user=msftusr SQL_APPLY_MSFT_password=msftpwd // Login information used when applying to an Oracle database SQL_APPLY_ORACLE_version=ORACLE10g SQL_APPLY_ORACLE_server=oradb SQL_APPLY_ORACLE_user=orausr SQL_APPLY_ORACLE_password=orapwd // Login information used when applying to a Sybase database SQL_APPLY_SYBASE_version=SYBASE125 SQL_APPLY_SYBASE_database=sybdb SQL_APPLY_SYBASE_server=sybdb SQL_APPLY_SYBASE_user=sybusr SQL_APPLY_SYBASE_password=sybpwd ... (THIS GOES ON)

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• Database advantages? Access, MySQL, msSQL, or any others?

  - by JimZ

  Dear all Stackoverflowers, I just started to learn programming and now I'm putting this question online based on a quote: no question is silly My work needs to develop a order system based on web, which wants a database system. Since using Excel for years as a general office user, I naturally turn this to Access. However, most people say Access is very limited comparing to MySQL or MSSQL, or any other more professional database system. But after developing some functions for my company's order system, I really find Access can fulfill my request. And I also tried MSSQL to develop, which I found it not quite convenient to use. I have searched in stackoverflow and find no general answer about my doubt. Now I am sincerely hoping some experienced and professional developers could clear my doubts. Now I'm listing some Access advantages, which I don't think other database system have. I hope you could help me also find these advantages in others. 1. Access is portable, I can just copy a xxx.accdb file to my company and continue with development. 2. Access is easy to generate helpful table, for example, it will automatically generate a field that can automatically count, could be used as primary key value. 3. it is more compatable with Excel, to display and filter data. 4. importantly, it nerely needs no environment to setup, just needs MS Office to be installed. ............others However, I also find some points that MSSQL is advantaged: 1. security reasons 2. easy to backup, ( just use BACKUP..... sql statement to do it) 3. can edit stored procedure to save some functions to database ...............others specifically, I wish some friends could tell me how to make other database portable? since I usually work both at home and in office. It's a headache to move MSSQL work to my office, since the version of MSSQL is not the same. Thank you all and best regards, :)

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• Apache 2.4 + PHP-FPM + ProxyPassMatch

  - by apfelbox

  I recently installed Apache 2.4 on my local machine, together with PHP 5.4.8 using PHP-FPM. Everything went quite smoothly (after a while...) but there is still a strange error: I configured Apache for PHP-FPM like this: <VirtualHost *:80> ServerName localhost DocumentRoot "/Users/apfelbox/WebServer" ProxyPassMatch ^/(.*\.php(/.*)?)$ fcgi://127.0.0.1:9000/Users/apfelbox/WebServer/$1 </VirtualHost> It works, for example if I call http://localhost/info.php I get the correct phpinfo() (it is just a test file). If I call a directory however, I get a 404 with body File not found. and in the error log: [Tue Nov 20 21:27:25.191625 2012] [proxy_fcgi:error] [pid 28997] [client ::1:57204] AH01071: Got error 'Primary script unknown\n' Update I now tried doing the proxying with mod_rewrite: <VirtualHost *:80> ServerName localhost DocumentRoot "/Users/apfelbox/WebServer" RewriteEngine on RewriteCond %{REQUEST_FILENAME} !-d RewriteRule ^/(.*\.php(/.*)?)$ fcgi://127.0.0.1:9000/Users/apfelbox/WebServer/$1 [L,P] </VirtualHost> But the problem is: it is always redirecting, because on http://localhost/ automatically http://localhost/index.php is requested, because of DirectoryIndex index.php index.html Update 2 Ok, so I think "maybe check whether there is a file to give to the proxy first: <VirtualHost *:80> ServerName localhost DocumentRoot "/Users/apfelbox/WebServer" RewriteEngine on RewriteCond %{REQUEST_FILENAME} !-d RewriteCond %{REQUEST_FILENAME} -f RewriteRule ^/(.*\.php(/.*)?)$ fcgi://127.0.0.1:9000/Users/apfelbox/WebServer/$1 [L,P] </VirtualHost> Now the complete rewriting does not work anymore... Update 3 Now I have this solution: ServerName localhost DocumentRoot "/Users/apfelbox/WebServer" RewriteEngine on RewriteCond /Users/apfelbox/WebServer/%{REQUEST_FILENAME} -f RewriteRule ^/(.*\.php(/.*)?)$ fcgi://127.0.0.1:9000/Users/apfelbox/WebServer/$1 [L,P] First check, that there is a file to pass to PHP-FPM (with the full and absolute path) and then do the rewriting. This does not work when using URL rewriting inside a subdirectory, also it fails for URLs like http://localhost/index.php/test/ So back to square one. Any ideas?

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• SSH public key authentication -- always require users to generate their own keypair?

  - by schinazi

  I was working with a partner today that I needed to upload files to my server using scp. I have passwords turned off in the server's SSH configuration, so I wanted them to use public key authentication. I generated the keypair for them on the server and gave them the private key and put the public key in the appropriate authorized_keys file. After a bunch of problems with them setting up their job, they finally got a more experienced sysadmin involved on their end, and he scolded me for handling the key generation this way. He said that by giving them a private key generated on my system, I had enabled them to do a brute-force attack against other keys generated on the same server. I even asked him "so if I have an account on a server, and I can log in with a password but I want to automate something and I generate a keypair on that system, does that then give me an attack vector for brute forcing other users' keys?" and he said yes. I've never heard of this, is it true? Can anyone point me to a discussion of this attack? Thanks in advance.

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• Windows Vista Nested Desktop Folders Problem

  - by Samuel Walker

  I have no idea how, nor when this happened, and it's started to really quite annoy me. When navigating through Explorer, by clicking on Icons I have C:\Users\Samuel\Desktop (Icon is the blue special Desktop icon), which contains the items I see on my Desktop. I then have the following folder: C:\Users\Samuel\Desktop (Icon is the standard yellow folder icon), which contains many program shortcuts, and is completely seperate from the other C:\Users\Samuel\Desktop Then in the Yellow Icon Desktop I have the sub-folder Desktop with the blue icon that is a direct mirror of the blue C:\Users\Samuel\Desktop folder (as in a new folder / file shows up in both). In explorer when I directly type C:\Users\Samuel\Desktop I am taken to the Yellow folder version. If I go to C:\Users\Samuel\Desktop\Desktop I am taken to the Blue folder version. Finally, from cmd cd'ing to C:\Users\Samuel\Desktop takes me to the Yellow folder version whilst C:\Users\Samuel\Desktop\Desktop takes me to the blue folder version. How on earth can I get rid of the yellow folder version leaving the blue C:\Users\Samuel\Desktop. I can't delete either as it says they're in use. UPDATE: Ok, so it looks like doing a dir from cmd lists only one Desktop folder - the Yellow one. In addition, it looks like I can't delete either of them (given that they both contain my 'Desktop'

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• How do you install .net4 on a Server 2008 r2 machine through psremoting in powershell?

  - by Jake

  I need to write a script that installs .net 4 remotely using powershell to a group of Server 2008 R2 machines. I based my script off of http://social.technet.microsoft.com/Forums/en-US/winserverpowershell/thread/3045eb24-7739-4695-ae94-5aa7052119fd/. enter-pssession -computername localhost $arglist = "/q /norestart /log C:\Users\tempuser\Desktop\dotnetfx4" $filepath = "C:\Users\tempuser\Desktop\dotNetFx40_Full_setup.exe" Start-Process -FilePath $filepath -ArgumentList $arglist -Wait -PassThru After running the command I would get the following log errors (running the same lines locally would install .net without error): Action: Downloading Item Failed to CreateJob : hr= 0x80200014 Action: Performing actions on all Items Action: Performing Action on Exe at C:\Users\tempuser\Desktop\dotnetfx4\SetupUtility.exe Exe (C:\Users\tempuser\Desktop\dotnetfx4\SetupUtility.exe) succeeded. Exe Log File: dd_SetupUtility.txt Action complete Action: ServiceControl - Stop clr_optimization_v2.0.50727_32 ServiceControl operation succeeded! Action complete Action: ServiceControl - Stop clr_optimization_v2.0.50727_64 ServiceControl operation succeeded! Action complete Action: Performing Action on Exe at C:\Users\tempuser\AppData\Local\Temp\Microsoft .NET Framework 4 Setup_4.0.30319\Windows6.1-KB958488-v6001-x64.msu Exe (C:\Users\tempuser\AppData\Local\Temp\Microsoft .NET Framework 4 Setup_4.0.30319\Windows6.1-KB958488-v6001-x64.msu) failed with 0x5 - Access is denied. . PerformOperation on exe returned exit code 5 (translates to HRESULT = 0x5) Action complete OnFailureBehavior for this item is to Rollback. Action: Performing actions on all Items Action complete Action complete Action: Downloading http://go.microsoft.com/fwlink/?LinkId=164184&clcid=0x409 using WinHttp WinHttpDetectAutoProxyConfigUrl failed with error: 12180 Unable to retrieve Proxy information although WinHttpGetIEProxyConfigForCurrentUser called succeeded Action complete C:\Users\tempuser\AppData\Local\Temp\Microsoft .NET Framework 4 Setup_4.0.30319\TMPF279.tmp.exe: Verifying signature for netfx_Core.mzz C:\Users\tempuser\AppData\Local\Temp\Microsoft .NET Framework 4 Setup_4.0.30319\TMPF279.tmp.exe Signature verified successfully for netfx_Core.mzz Action complete Decompression completed with code: 16389 Decompression of payload failed: C:\Users\tempuser\AppData\Local\Temp\Microsoft .NET Framework 4 Setup_4.0.30319\netfx_Core.mzz Action complete Final Result: Installation failed with error code: (0x80074005) (Elapsed time: 0 00:00:28). Is there some security setting or perhaps something else I've missed?

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• Does smartermail store the parsed email messages in a sql database I could access directly?

  - by Blankman

  Does smartermail store the parsed email messages in a sql database I could access directly?

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• Openldap, groups, admin groups, etc

  - by Juan Diego

  We have a samba server as PDC with OpenLDAP. So far everything is working, even windows 7 can log on to the Domain. Here is the tricky part. We have many departments, each department has it's own IT guys, and these IT guy should be able to create users in their department and change any info of the users in their department. My Idea was to create 2 groups for each department, For example: Department1 and Admins Department1. Admins Deparment1 has "write" priviledges for members of group Department dn: ou=People,dc=mydomain,dc=com,dc=ec objectClass: top objectClass: organizationalUnit ou: People dn: cn=Admins,ou=Group,dc=mydomain,dc=com,dc=ec objectClass: groupOfNames objectClass: top cn: Admins dn: cn=Admins Department1,cn=Admins,ou=Group,dc=mydomain,dc=com,dc=ec objectClass: groupOfNames objectClass: top cn: Admins Department1 member: uid=jdc,ou=People,dc=mydomain,dc=com,dc=ec structuralObjectClass: groupOfNames I dont know if you should make Department1 as part of Domain Users dn: cn=Deparment1,cn=Domain Users,ou=Group,dc=mydomain,dc=com,dc=ec objectClass: groupOfNames objectClass: top cn: Deparment1 member: uid=user1,ou=People,dc=mydomain,dc=com,dc=ec Or just create the deparments like this. dn: cn=Deparment1,ou=Group,dc=mydomain,dc=com,dc=ec objectClass: groupOfNames objectClass: top cn: Deparment1 member: uid=user1,ou=People,dc=mydomain,dc=com,dc=ec I seems that when you use smbldap tools bydefault the users are part of Domain Users even if you dont have them as part of Domain Users in the memberUid attribute, when I use finger they showup as part of the Domain Users group. I dont want the Departments Admins to be Domain Admins because they have power over all the users, unless I am mistaken. I also have trouble with the ACLs. I was trying to create an acl for members of this Admins group, I was trying with this search, but didnt work ldapsearch -x "(&(objectClass=organizationalPerson)(member=cn=Admins Department1,ou=Group,dc=mydomain,dc=com,dc=ec))" I am open to suggestions.

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• Are there any problems migrating users from OSX 10.4.11 server to 10.6.6. server using WGM?

  - by Geoff Hardman

  I have just set up a new Mac server running 10.6.6. Installation went smoothly and all appears ok. Can create a new user through WGM and logon to the server from one of our local client systems. Imported the old users from the 10.4 system using WGM but the new system will not create home directories for these users and will not let them log on. I have read that there are issues using this method but can not find any detail as to why. Not wishing to recreate over 350 users from scratch I am looking for an easier solution. Can anyone help? The new server is 10.6.6. We use Open Directory and AFP. The paths are the same as the old server.

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• Are there cloud network drives that let users lock files or mark them as "in use"?

  - by Brandon Craig Rhodes

  Having spent several hours reading about the features and limitations of services like DropBox and Jungle Disk and the hundreds of competitors they seem to have (as though everyone with an AWS account these days goes ahead and writes a file sharing application just for fun), I have yet to find one that would let a team of people at a small business collaborate without stepping all over each other's toes. At a small business there are often many small documents per project — estimates, contracts, project plans, budgets — and team members frequently have to open and edit them, with all sorts of problems happening if two people edit a file at once. Even if a sharing service is smart enough to keep both versions of the file created, most small-business software (like word processors, spreadsheets, estimating software, or billing systems) has no way to compare — much less to merge! — the changes in two rival versions of a file that two people edited at the same time without each other's knowledge. So, my question: are their cloud-based file sharing solutions that not only provide a virtual network drive that people can access, but that also let users lock files — even if it's not a real lock but just a flag or indicator — that could possibly prevent remote workers from both editing the same file at once? Having one person wait for another person to finish editing is a very, very small inconvenience compared to the hour or more than it can take to compare two estimates by hand until you find and resolve the rival changes. Given this fact, I am surprised that almost none of the popular file sharing solutions seem to recognize this problem and provide some solution! Does anyone know of a service that does?

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• tacacs+ integrated with LDAP or database. Which is better?

  - by chingupt

  We are setting up TACACS+ in our network which is a mix of Cisco AP's and other brands. However we have a centralized managemnet system which allows our customers to configure services. Hence we would like to setup a tacacs+ server integrated with some central system. We have two options: Integrate with a central Database server which stores the user configuration. OR Integrate with a LDAP Server. Which is a better solution? Can you please suggest the pros and cons of using LDAP or Database? TIA Sachin

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