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  • problem in extracting the data from text file

    - by parijat24
    hello , i am new to python , and I want to extract the data from this format FBpp0143497 5 151 5 157 PF00339.22 Arrestin_N Domain 1 135 149 83.4 1.1e-23 1 CL0135 FBpp0143497 183 323 183 324 PF02752.15 Arrestin_C Domain 1 137 138 58.5 6e-16 1 CL0135 FBpp0131987 60 280 51 280 PF00089.19 Trypsin Domain 14 219 219 127.7 3.7e-37 1 CL0124 to this format FBpp0143497 5 151 Arrestin_N 1.1e-23 FBpp0143497 183 323 Arrestin_C 6e-16 I have written code in hope that it works but it does not work , please help! file = open('/ddfs/user/data/k/ktrip_01/hmm.txt','r') rec = file.read() for line in rec : field = line.split("\t") print field print field[:] print '>',field[0] print field[1], field[2], field[6], field[12] the hmmtext file is FBpp0143497 5 151 5 157 PF00339.22 Arrestin_N Domain 1 135 149 83.4 1.1e-23 1 CL0135 FBpp0143497 183 323 183 324 PF02752.15 Arrestin_C Domain 1 137 138 58.5 6e-16 1 CL0135 FBpp0131987 60 280 51 280 PF00089.19 Trypsin Domain 14 219 219 127.7 3.7e-37 1 CL0124

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  • data loading - app launching on tableview

    - by wallou
    hi, i encounter an issue with my application. On one hand when my app launches, the first view displayed is a tableview within a tableviewcontroller. On the other hand my app calls a web service to collect data. These methods are in MyAppDelegate\applicationDidFinishLaunching. The thing is that my tableview is made of custom cells that need data from the web service. I noticed that the view (with the tableview) is launched first and then MyAppDelegate\applicationDidFinishLaunchin is executed. As a result the labels of my custom cells are all equal to null as my arrays aren't filled yet by the web service. I would like to know the proper way to make it. If anyone has an idea please tell me. Wallou

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  • What machine learning algorithms can be used in this scenario?

    - by ExceptionHandler
    My data consists of objects as follows. Obj1 - Color - shape - size - price - ranking So I want to be able to predict what combination of color/shape/size/price is a good combination to get high ranking. Or even a combination could work like for eg: in order to get good ranking, the alg predicts best performance for this color and this shape. Something like that. What are the advisable algorithms for such a prediction? Also may be if you can briefly explain how I can approach towards the model building I would really appreciate it. Say for eg: my data looks like Blue pentagon small $50.00 #5 Red Squre large $30.00 #3 So what is a useful prediction model that I should look at? What algorithm should I try to predict like say highest weightage is for price followed by color and then size. What if I wanted to predict in combinations like a Red small shape is less likely to higher rank compared to pink small shape . (In essence trying to combine more than one nominal values column to make the prediction)

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  • .net: How do you feed a winform after clicking on a row of a datagridview of search form?

    - by odiseh
    I have a winform which is responsible for doing a search by some conditions that users enters and then selects the records from a Database. The search form has a data grid view which shows the result. After searching, user clikcs on a row of the datagridview and then another form (for example frmShowDetails) will be displayed. My question is when displaying frmShowDetails, what are your suggestions to send the id of selected row to frmShowDetails in order to feed it to show data in .net? Do you use form property or a private mariable which sets by only form constructor? Thank you

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  • Changing populated DataTable column data types

    - by TonE
    Hi, I have a System.Data.DataTable which is populated by reading a CSV file which sets the datatype of each column to string. I want to append the contents of the DataTable to an existing database table - currently this is done using SqlBulkCopy with the DataTable as the source. However, the column data types of the DataTable need to be changed to match the schema of the target database table, handling null values. I am not very familiar with ADO.NET so have been search for a clean way of doing this? Thanks.

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  • Javascript - use to load xml data from URL

    - by spenf
    I have this url with some xml data in it: http://64.182.231.116/~spencerf/union_college/Upperclass_Sample_Menu.xml And I would like to load this xml data into my javascript script so I can parse it. I am using parse.com Javascript SDK, in there cloud code. Here is the code I have tried: Parse.Cloud.define("next", function(request, response) { response.success("Hello world!"); $.ajax({ url: 'http://64.182.231.116/~spencerf/union_college/Upperclass_Sample_Menu.xml', // name of file you want to parse dataType: "xml", // type of file you are trying to read success: parse, // name of the function to call upon success error: function(){alert("Error: Something went wrong");} }); }); But when I run this I get an error: $ is not defined at main.js:

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  • Passing Large amount of data in PHP.

    - by Simple
    I would like to know what is the best way to pass a large amount of XML data from one PHP script to another. I have a script that reads in an XML feed of jobs. I would like to have the script display a list of the job titles as links. When the user clicks a link they would be taken to another page displaying the details for that job. The job details are too large to send in the query string, and it seems poor style to start a session for data that isn't specific to that user. Any ideas?

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  • Data-binding taking too long to update

    - by Justin
    In my application I have this code in my view model: hiddenTextContainer.PreHideVerticalOffset = VerticalOffset; hiddenTextContainer.HiddenText = Text.Remove(SelectionStart, SelectionLength); hiddenTextContainer.HasHiddenText = true; hiddenTextContainer.NonHiddenTextStart = SelectionStart; Text = Text.Substring(SelectionStart, SelectionLength); SelectionStart = Text.Length; hiddenTextContainer.ImmediatePostHideVerticalOffset = VerticalOffset; This code is used to hide selected text in a textbox. Text is a string property data bound to the text property of a textbox and VerticalOffset is a double property data bound to the VerticalOffset property of that same textbox. I need to save the VerticalOffset before and after the hiding of selected text takes place, but with my code below both hiddenTextContainer.PreHideVerticalOffset and hiddenTextContainer.ImmediatePostHideVerticalOffset are always set to the same value no matter what. I have figured out that this is because the text of the textbox has not been updated by the time the code reaches: hiddenTextContainer.ImmediatePostHideVerticalOffset = VerticalOffset; Is there any way I can fix this?

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  • memcpy does not copy the data

    - by user437777
    I am caught up with a weird problem. I have one build that copies data using memcpy, while another build does not. I don't understand why, because the relevant file is still the same. I am using following code: memcpy(pxCurrentInfo, &pxInfoBuffer->axgInfoBuffer[0], sizeof(tInfo)); Data in pxInfoBuffer is fine. When I check pxCurrentInfo they are all 0s. tInfo is a structure. To give a pointer, when I put the break point and change the value pxCurrentInfo->xDL.eMethod=0 it automatically updates/copies all the correct info from pxInfoBuffer->axgInfoBuffer[0], afterwards. I don't know why.

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  • Django model data consistency

    - by Mark
    When creating a form, you can define a bunch of methods, clean_xyz, to make sure the data gets forced into the correct format. Is there any way to do this on a model level? Perhaps I can override the field setters somehow? I want it so that if I write something like my_address.postal_code = 'a1b2c3' It will automatically get formatted into A1B 2C3. Perhaps throw an exception if it can't be converted. That way I know I'll never have any malformed data in the database.

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  • Codeigniter: Using data in a controller

    - by Kevin Brown
    I'm new to php and CI, and I'm having some trouble in my controller. I feel that I'm doing this the wrong way, and it could be easier, I just don't know the syntax: $data['members'] = $this->home_model->getUser($id); $credit = $this->home_model->getCredit($id); if ($credit == '0'){stuff...} So I'm getting the user's data that has their the same information as "getCredit" does, but I don't know how to get the single variable that I need for my if statement... How can I just use the "getUser" function so that I'm not pulling redundant information?

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  • jQuery.post not working when using data type json

    - by swift
    I have been trying to utilize json in this jQuery.post because I need to return two values from my executed php. The code was working when I was not implementing json. I need to see if a promo code entered is valid for a particular broker. The two variables I need back are the instant message whether or not it's valid (this is displayed to the user) and I need to update a hidden field that will be used later while updating the database. The jQuery.post does not seem to be firing at all, but the code directly above it (the ajax-loader.gif) is working. I did re-write the whole thing at one point using jQuery.ajax, and had issues there too. Granted, I have probably been looking at this too long and have tried to re-write too many times, but any help is greatly appreciated!! Here's the jQuery.post <!-- Below Script is for Checking Promo Code Against Database--> <script type="text/javascript"> jQuery(document).ready(function() { jQuery("#promocode").keyup(function (e) { //removes spaces from PromoCode jQuery(this).val(jQuery(this).val().replace(/\s/g, '')); var promocode = jQuery(this).val(); var brokerdealerid = document.getElementById("BrokerDealerId").value; if(promocode.length > 0 ){ jQuery("#promo-result").html('<img src="../imgs/ajax-loader.gif" />'); jQuery.post( '../check_promocode.php', {promocode:promocode, brokerdealerid:brokerdealerid}, function(data) { $("#promo-result").html(data.promoresult); $("#promo-result-valid").html(data.promovalid); }, "json"); } }); }); </script> <!-- End Script is for Checking Promo Code Against Database--> Here's relevant code from check_promocode.php: //sanitize incoming parameters if (isset($_POST['brokerdealerid'])) $brokerdealerid = sanitizeMySQL($_POST['brokerdealerid']); $promocode = sanitizeMySQL($promocode); //check promocode in db $results = mysql_query("SELECT PromotionCodeIdentifier FROM PromotionCode WHERE PromotionCodeIdentifier='$promocode' AND BrokerDealerId='$brokerdealerid' AND PromotionCodStrtDte <= CURDATE() AND PromotionCodExpDte >= CURDATE()"); //return total count $PromoCode_exist = mysql_num_rows($results); //total records //if value is more than 0, promocode is valid if($PromoCode_exist) { echo json_encode(array("promoresult"=>"Promotion Code Valid", "promovalid"=>"Y")); exit(); }else{ echo json_encode(array("promoresult"=>"Invalid Promotion Code", "promovalid"=>"N")); exit(); }

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  • Pass database data to multiples views-Laravel

    - by user3696018
    I have a database with details of daily sales. To query a database, I have a form in a view with parameters that will query as date of admission, client and others. The result is shown in another view with the daily details of income, and below is a summary of the article do all entered. The summary I wish to transfer to another view, try to view :: composer but only transfer the empty query (I saw it with debug bar). Just appeared an empty view. How I can transfer data from the database without the latter view is empty? The second html view is totaly diferent , only the data is the same.

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  • Pass data to another page

    - by user2331416
    I am trying to pass some data from one page to another page by using jquery but it dose not working, below is the code which I want to click the text in source page and the destination page will hide the current text. Source page: <html> <head> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script> <script type="text/javascript"> $(function () { $("a.pass").bind("click", function () { var url = "Destination.html?name=" + encodeURIComponent($("a.pass").text()); window.location.href = url; }); }); </script> </head> <body> <a class="pass">a</a><br /> <a class="pass">b</a><br /> <a class="pass">c</a><br /> <a class="pass">d</a> </body> </html> Destination page: <html> <head> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script> <script type="text/javascript"> var queryString = new Array(); $(function () { if (queryString.length == 0) { if (window.location.search.split('?').length > 1) { var params = window.location.search.split('?')[1].split('&'); for (var i = 0; i < params.length; i++) { var key = params[i].split('=')[0]; var value = decodeURIComponent(params[i].split('=')[1]); queryString[key] = value; } } } if (queryString["name"] != null) { var data = queryString["name"] $("p.+'data'").hide(); } }); </script> </head> <body> <p class="a">a</p> <p class="b">b</p> <p class="c">c</p> <p class="d">d</p> </body> </html> Please Help.

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  • PHP Passing Data to a Specific Class? (Data Encapsulation)

    - by Adam184
    I've learned that OOP is all about data encapsulation, but what about passing data between classes that have nothing to do with each other (would the below example be worthy of using extends)? class Dog { private $secretVar; public function getSecretVar() { $this->secretVar = 'psst... only for rainbow!'; return $this->secretVar; } } class Rainbow { public function __construct(Dog $Dog) { print_r($Dog->getSecretVar()); } } $Dog = new Dog(); $Rainbow = new Rainbow($Dog); // ... classes that don't need the $secretVar How would you encapsulate $secretVar for only classes Dog and Rainbow? As of now, anyone can call getSecretVar(), and I'm having a hard time allowing that to happen as it seems to defeat the whole point of encapsulation.

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  • how to visualize (value, count) dataset with thousands data points

    - by user510040
    I have a file with 2 numeric columns: value and count. File may have 5000 rows. I do plot(value, count) to find the shape of distribution. But because there are too many data points the picture is not very clear. Do you know better visualization approach? Probably histograms or barplot with grouping close values on x axis will be the better way to look on data? I cannot figure out the syntax of using histogram or barplot for my case.

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  • How to insert scraping data to mysql

    - by user1887288
    i am fetching data from other websites can any one tell me how to insert fetch data to mysql database Below code i am using to fetch results coming $urls = $_POST["urls"]; require_once('simple_html_dom.php'); $useragent = 'Googlebot/2.1 (http://www.googlebot.com/bot.html)'; foreach ($urls as $url) { $curl = curl_init(); curl_setopt($curl, CURLOPT_URL, $url); curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1); curl_setopt($curl, CURLOPT_CONNECTTIMEOUT, 20); curl_setopt($curl, CURLOPT_USERAGENT, $useragent); $str = curl_exec($curl); curl_close($curl); $html= str_get_html($str); foreach($html->find('span.price') as $e) echo $e->innertext . '<br>'; }

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  • Securing an ADF Application using OES11g: Part 2

    - by user12587121
    To validate the integration with OES we need a sample ADF Application that is rich enough to allow us to test securing the various ADF elements.  To achieve this we can add some items including bounded task flows to the application developed in this tutorial. A sample JDeveloper 11.1.1.6 project is available here. It depends on the Fusion Order Demo (FOD) database schema which is easily created using the FOD build scripts.In the deployment we have chosen to enable only ADF Authentication as we will delegate Authorization, mostly, to OES.The welcome page of the application with all the links exposed looks as follows: The Welcome, Browse Products, Browse Stock and System Administration links go to pages while the Supplier Registration and Update Stock are bounded task flows.  The Login link goes to a basic login page and once logged in a link is presented that goes to a logout page.  Only the Browse Products and Browse Stock pages are really connected to the database--the other pages and task flows do not really perform any operations on the database. Required Security Policies We make use of a set of test users and roles as decscribed on the welcome page of the application.  In order to exercise the different authorization possibilities we would like to enforce the following sample policies: Anonymous users can see the Login, Welcome and Supplier Registration links. They can also see the Welcome page, the Login page and follow the Supplier Registration task flow.  They can see the icon adjacent to the Login link indicating whether they have logged in or not. Authenticated users can see the Browse Product page. Only staff granted the right can see the Browse Product page cost price value returned from the database and then only if the value is below a configurable limit. Suppliers and staff can see the Browse Stock links and pages.  Customers cannot. Suppliers can see the Update Stock link but only those with the update permission are allowed to follow the task flow that it launches.  We could hide the link but leave it exposed here so we can easily demonstrate the method call activity protecting the task flow. Only staff granted the right can see the System Administration link and the System Administration page it accesses. Implementing the required policies In order to secure the application we will make use of the following techniques: EL Expressions and Java backing beans: JSF has the notion of EL expressions to reference data from backing Java classes.  We use these to control the presentation of links on the navigation page which respect the security contraints.  So a user will not see links that he is not allowed to click on into. These Java backing beans can call on to OES for an authorization decision.  Important Note: naturally we would configure the WLS domain where our ADF application is running as an OES WLS SM, which would allow us to efficiently query OES over the PEP API.  However versioning conflicts between OES 11.1.1.5 and ADF 11.1.1.6 mean that this is not possible.  Nevertheless, we can make use of the OES RESTful gateway technique from this posting in order to call into OES. You can easily create and manage backing beans in Jdeveloper as follows: Custom ADF Phase Listener: ADF extends the JSF page lifecycle flow and allows one to hook into the flow to intercept page rendering.  We use this to put a check prior to rendering any protected pages, again calling on to OES via the backing bean.  Phase listeners are configured in the adf-settings.xml file.  See the MyPageListener.java class in the project.  Here, for example,  is the code we use in the listener to check for allowed access to the sysadmin page, navigating back to the welcome page if authorization is not granted:                         if (page != null && (page.equals("/system.jspx") || page.equals("/system"))){                             System.out.println("MyPageListener: Checking Authorization for /system");                             if (getValue("#{oesBackingBean.UIAccessSysAdmin}").toString().equals("false") ){                                   System.out.println("MyPageListener: Forcing navigation away from system" +                                       "to welcome");                                 NavigationHandler nh = fc.getApplication().getNavigationHandler();                                   nh.handleNavigation(fc, null, "welcome");                               } else {                                 System.out.println("MyPageListener: access allowed");                              }                         } Method call activity: our app makes use of bounded task flows to implement the sequence of pages that update the stock or allow suppliers to self register.  ADF takes care of ensuring that a bounded task flow can be entered by only one page.  So a way to protect all those pages is to make a call to OES in the first activity and then either exit the task flow or continue depending on the authorization decision.  The method call returns a String which contains the name of the transition to effect. This is where we configure the method call activity in JDeveloper: We implement each of the policies using the above techniques as follows: Policies 1 and 2: as these policies concern the coarse grained notions of controlling access to anonymous and authenticated users we can make use of the container’s security constraints which can be defined in the web.xml file.  The allPages constraint is added automatically when we configure Authentication for the ADF application.  We have added the “anonymousss” constraint to allow access to the the required pages, task flows and icons: <security-constraint>    <web-resource-collection>      <web-resource-name>anonymousss</web-resource-name>      <url-pattern>/faces/welcome</url-pattern>      <url-pattern>/afr/*</url-pattern>      <url-pattern>/adf/*</url-pattern>      <url-pattern>/key.png</url-pattern>      <url-pattern>/faces/supplier-reg-btf/*</url-pattern>      <url-pattern>/faces/supplier_register_complete</url-pattern>    </web-resource-collection>  </security-constraint> Policy 3: we can place an EL expression on the element representing the cost price on the products.jspx page: #{oesBackingBean.dataAccessCostPrice}. This EL Expression references a method in a Java backing bean that will call on to OES for an authorization decision.  In OES we model the authorization requirement by requiring the view permission on the resource /MyADFApp/data/costprice and granting it only to the staff application role.  We recover any obligations to determine the limit.  Policy 4: is implemented by putting an EL expression on the Browse Stock link #{oesBackingBean.UIAccessBrowseStock} which checks for the view permission on the /MyADFApp/ui/stock resource. The stock.jspx page is protected by checking for the same permission in a custom phase listener—if the required permission is not satisfied then we force navigation back to the welcome page. Policy 5: the Update Stock link is protected with the same EL expression as the Browse Link: #{oesBackingBean.UIAccessBrowseStock}.  However the Update Stock link launches a bounded task flow and to protect it the first activity in the flow is a method call activity which will execute an EL expression #{oesBackingBean.isUIAccessSupplierUpdateTransition}  to check for the update permission on the /MyADFApp/ui/stock resource and either transition to the next step in the flow or terminate the flow with an authorization error. Policy 6: the System Administration link is protected with an EL Expression #{oesBackingBean.UIAccessSysAdmin} that checks for view access on the /MyADF/ui/sysadmin resource.  The system page is protected in the same way at the stock page—the custom phase listener checks for the same permission that protects the link and if not satisfied we navigate back to the welcome page. Testing the Application To test the application: deploy the OES11g Admin to a WLS domain deploy the OES gateway in a another domain configured to be a WLS SM. You must ensure that the jps-config.xml file therein is configured to allow access to the identity store, otherwise the gateway will not b eable to resolve the principals for the requested users.  To do this ensure that the following elements appear in the jps-config.xml file: <serviceProvider type="IDENTITY_STORE" name="idstore.ldap.provider" class="oracle.security.jps.internal.idstore.ldap.LdapIdentityStoreProvider">             <description>LDAP-based IdentityStore Provider</description>  </serviceProvider> <serviceInstance name="idstore.ldap" provider="idstore.ldap.provider">             <property name="idstore.config.provider" value="oracle.security.jps.wls.internal.idstore.WlsLdapIdStoreConfigProvider"/>             <property name="CONNECTION_POOL_CLASS" value="oracle.security.idm.providers.stdldap.JNDIPool"/></serviceInstance> <serviceInstanceRef ref="idstore.ldap"/> download the sample application and change the URL to the gateway in the MyADFApp OESBackingBean code to point to the OES Gateway and deploy the application to an 11.1.1.6 WLS domain that has been extended with the ADF JRF files. You will need to configure the FOD database connection to point your database which contains the FOD schema. populate the OES Admin and OES Gateway WLS LDAP stores with the sample set of users and groups.  If  you have configured the WLS domains to point to the same LDAP then it would only have to be done once.  To help with this there is a directory called ldap_scripts in the sample project with ldif files for the test users and groups. start the OES Admin console and configure the required OES authorization policies for the MyADFApp application and push them to the WLS SM containing the OES Gateway. Login to the MyADFApp as each of the users described on the login page to test that the security policy is correct. You will see informative logging from the OES Gateway and the ADF application to their respective WLS consoles. Congratulations, you may now login to the OES Admin console and change policies that will control the behaviour of your ADF application--change the limit value in the obligation for the cost price for example, or define Role Mapping policies to determine staff access to the system administration page based on user profile attributes. ADF Development Notes Some notes on ADF development which are probably typical gotchas: May need this on WLS startup in order to allow us to overwrite credentials for the database, the signal here is that there is an error trying to access the data base: -Djps.app.credential.overwrite.allowed=true Best to call Bounded Task flows via a CommandLink (as opposed to a go link) as you cannot seem to start them again from a go link, even having completed the task flow correctly with a return activity. Once a bounded task flow (BTF) is initated it must complete correctly  via a return activity—attempting to click on any other link whilst in the context of a  BTF has no effect.  See here for example: When using the ADF Authentication only security approach it seems to be awkward to allow anonymous access to the welcome and registration pages.  We can achieve anonymous access using the web.xml security constraint shown above (where no auth-constraint is specified) however it is not clear what needs to be listed in there….for example the /afr/* and /adf/* are in there by trial and error as sometimes the welcome page will not render if we omit those items.  I was not able to use the default allPages constraint with for example the anonymous-role or the everyone WLS group in order to be able to allow anonymous access to pages. The ADF security best practice advises placing all pages under the public_html/WEB-INF folder as then ADF will not allow any direct access to the .jspx pages but will only allow acces via a link of the form /faces/welcome rather than /faces/welcome.jspx.  This seems like a very good practice to follow as having multiple entry points to data is a source of confusion in a web application (particulary from a security point of view). In Authentication+Authorization mode only pages with a Page definition file are protected.  In order to add an emty one right click on the page and choose Go to Page Definition.  This will create an empty page definition and now the page will require explicit permission to be seen. It is advisable to give a unique context root via the weblogic.xml for the application, as otherwise the application will clash with any other application with the same context root and it will not deploy

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  • Cloud Computing Architecture Patterns: Don’t Focus on the Client

    - by BuckWoody
    Normally I try to put topics in the positive in other words "Do this" not "Don't do that". Sometimes its clearer to focus on what *not* to do. Popular development processes often start with screen mockups, or user input descriptions. In a scale-out pattern like Cloud Computing on Windows Azure, that's the wrong place to start. Start with the Data    Instead, I recommend that you start with the data that a process requires. That data might be temporary or persisted, but starting with the data and its requirements helps to define not only the storage engine you need but also drives everything from security to the integrity of the application. For instance, assume the requirements show that the user must enter their phone number, and that this datum is used in a contact management system further down the application chain. For that datum, you can determine what data type you need (U.S. only or International?) the security requirements, whether it needs ACID compliance, how it will be searched, indexed and so on. From one small data point you can extrapolate out your options for storing and processing the data. Here's the interesting part, which begins to break the patterns that we've used for decades: all of the data doesn't have the same requirements. The phone number might be best suited for a list, or an element, or a string, with either BASE or ACID requirements, based on how it is used. That means we don't have to dump everything into XML, an RDBMS, a NoSQL engine, or a flat file exclusively. In fact, one record might use all of those depending on the use-case requirements. Next Is Data Management  With the data defined, we can move on to how to store the data. Again, the requirements now dictate whether we need a full relational calculus or set-based operations, or we can choose another method based on the requirements for the data. And breaking another pattern its OK to store in more than once, in more than one location. We do this all the time for reporting systems and Business Intelligence systems, so this is a pattern we need to think about even for OLTP data. Move to Data Transport How does the data get around? We can use a connection-based method, sending the data along a transport to the storage engine, but in some cases we may want to use a cache, a queue, the Service Bus, or Complex Event Processing. Finally, Data Processing Most RDBMS engines, NoSQL, and certainly Big Data engines not only store data, but can process and manipulate it as well. Its doubtful that you'll calculate that phone number right? Well, if you're the phone company, you most certainly will. And so we see that even once we've chosen the data type, storage and engine, the same element can have different computing requirements based on how it is used. Sure, We Need A Front-End At Some Point Not all data is entered by human hands in fact most data isn't. We don't really need a Graphical User Interface (GUI) we need some way for a GUI to get data into and out of the systems listed earlier.   But when we do need to allow users to enter or examine data, that should be left to the GUI that best fits the device the user has. Ever tried to use an application designed for a web browser on a phone? Or one designed for a tablet on a phone? Its usually quite painful. The siren song of "We'll just write one interface for all devices" is strong, and has beguiled many an unsuspecting architect. But they just don't work out.   Instead, focus on the data, its transport and processing. Create API calls or a message system that allows for resilient transport to the device or interface, and let it do what it does best. References Microsoft Architecture Journal:   http://msdn.microsoft.com/en-us/architecture/bb410935.aspx Patterns and Practices:   http://msdn.microsoft.com/en-us/library/ff921345.aspx Windows Azure iOS, Android, Windows 8 Mobile Devices SDK: http://www.windowsazure.com/en-us/develop/mobile/tutorials/get-started-ios/ Windows Azure Facebook SDK: http://ntotten.com/2013/03/14/using-windows-azure-mobile-services-with-the-facebook-sdk-for-windows-phone/

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  • Oh no! My padding's invalid!

    - by Simon Cooper
    Recently, I've been doing some work involving cryptography, and encountered the standard .NET CryptographicException: 'Padding is invalid and cannot be removed.' Searching on StackOverflow produces 57 questions concerning this exception; it's a very common problem encountered. So I decided to have a closer look. To test this, I created a simple project that decrypts and encrypts a byte array: // create some random data byte[] data = new byte[100]; new Random().NextBytes(data); // use the Rijndael symmetric algorithm RijndaelManaged rij = new RijndaelManaged(); byte[] encrypted; // encrypt the data using a CryptoStream using (var encryptor = rij.CreateEncryptor()) using (MemoryStream encryptedStream = new MemoryStream()) using (CryptoStream crypto = new CryptoStream( encryptedStream, encryptor, CryptoStreamMode.Write)) { crypto.Write(data, 0, data.Length); encrypted = encryptedStream.ToArray(); } byte[] decrypted; // and decrypt it again using (var decryptor = rij.CreateDecryptor()) using (CryptoStream crypto = new CryptoStream( new MemoryStream(encrypted), decryptor, CryptoStreamMode.Read)) { byte[] decrypted = new byte[data.Length]; crypto.Read(decrypted, 0, decrypted.Length); } Sure enough, I got exactly the same CryptographicException when trying to decrypt the data even in this simple example. Well, I'm obviously missing something, if I can't even get this single method right! What does the exception message actually mean? What am I missing? Well, after playing around a bit, I discovered the problem was fixed by changing the encryption step to this: // encrypt the data using a CryptoStream using (var encryptor = rij.CreateEncryptor()) using (MemoryStream encryptedStream = new MemoryStream()) { using (CryptoStream crypto = new CryptoStream( encryptedStream, encryptor, CryptoStreamMode.Write)) { crypto.Write(data, 0, data.Length); } encrypted = encryptedStream.ToArray(); } Aaaah, so that's what the problem was. The CryptoStream wasn't flushing all it's data to the MemoryStream before it was being read, and closing the stream causes it to flush everything to the backing stream. But why does this cause an error in padding? Cryptographic padding All symmetric encryption algorithms (of which Rijndael is one) operates on fixed block sizes. For Rijndael, the default block size is 16 bytes. This means the input needs to be a multiple of 16 bytes long. If it isn't, then the input is padded to 16 bytes using one of the padding modes. This is only done to the final block of data to be encrypted. CryptoStream has a special method to flush this final block of data - FlushFinalBlock. Calling Stream.Flush() does not flush the final block, as you might expect. Only by closing the stream or explicitly calling FlushFinalBlock is the final block, with any padding, encrypted and written to the backing stream. Without this call, the encrypted data is 16 bytes shorter than it should be. If this final block wasn't written, then the decryption gets to the final 16 bytes of the encrypted data and tries to decrypt it as the final block with padding. The end bytes don't match the padding scheme it's been told to use, therefore it throws an exception stating what is wrong - what the decryptor expects to be padding actually isn't, and so can't be removed from the stream. So, as well as closing the stream before reading the result, an alternative fix to my encryption code is the following: // encrypt the data using a CryptoStream using (var encryptor = rij.CreateEncryptor()) using (MemoryStream encryptedStream = new MemoryStream()) using (CryptoStream crypto = new CryptoStream( encryptedStream, encryptor, CryptoStreamMode.Write)) { crypto.Write(data, 0, data.Length); // explicitly flush the final block of data crypto.FlushFinalBlock(); encrypted = encryptedStream.ToArray(); } Conclusion So, if your padding is invalid, make sure that you close or call FlushFinalBlock on any CryptoStream performing encryption before you access the encrypted data. Flush isn't enough. Only then will the final block be present in the encrypted data, allowing it to be decrypted successfully.

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