Given a pack:// URI, what's the best way to tell whether a compiled resource (e.g. a PNG image, compiled with a Build Action of "Resource") actually exists at that URI?
After some stumbling around, I came up with this code, which works but is clumsy:
private static bool CanLoadResource(Uri uri)
{
try
{
Application.GetResourceStream(uri);
return true;
}
catch (IOException)
{
return false;
}
}
(Note that the Application.GetResources documentation is wrong -- it throws an exception if the resource isn't found, rather than returning null like the docs incorrectly state.) (The docs have been corrected, see comments below)
I don't like catching exceptions to detect an expected (non-exceptional) result. And besides, I don't actually want to load the stream, I just want to know whether it exists.
Is there a better way to do this, perhaps with lower-level resource APIs -- ideally without actually loading the stream and without catching an exception?
I've found a solution that I'm using which doesn't work directly with a pack Uri but instead looks up a resource by it's resource path. That being said, this example could be modified pretty easily to support a pack URI instead by just tacking on the resource path to the end of a uri which uses the Assembly to formulate the base part of the URI.
public static bool ResourceExists(string resourcePath)
{
var assembly = Assembly.GetExecutingAssembly();
return ResourceExists(assembly, resourcePath);
}
public static bool ResourceExists(Assembly assembly, string resourcePath)
{
return GetResourcePaths(assembly)
.Contains(resourcePath.ToLowerInvariant());
}
public static IEnumerable<object> GetResourcePaths(Assembly assembly)
{
var culture = System.Threading.Thread.CurrentThread.CurrentCulture;
var resourceName = assembly.GetName().Name + ".g";
var resourceManager = new ResourceManager(resourceName, assembly);
try
{
var resourceSet = resourceManager.GetResourceSet(culture, true, true);
foreach(System.Collections.DictionaryEntry resource in resourceSet)
{
yield return resource.Key;
}
}
finally
{
resourceManager.ReleaseAllResources();
}
}
Related
I am trying to integrate Hystrix javanica into my existing java EJB web application and facing 2 issues with running it.
When I try to invoke following service it always returns response from fallback method and I see that the Throwable object in fallback method has "com.netflix.hystrix.exception.HystrixTimeoutException" exception.
Each time this service is triggered, HystrixCommad and fallback methods are called multiple times around 50 times.
Can anyone suggest me with any inputs? Am I missing any configuration?
I am including following libraries in my project.
project libraries
I have setup my aspect file as follows:
<aspectj>
<weaver options="-verbose -showWeaveInfo"></weaver>
<aspects>
<aspect name="com.netflix.hystrix.contrib.javanica.aop.aspectj.HystrixCommandAspect"/>
</aspects>
</aspectj>
Here is my config.properties file in META-INF/config.properties
hystrix.command.default.execution.timeout.enabled=false
Here is my rest service file
#Path("/hystrix")
public class HystrixService {
#GET
#Path("clusterName")
#Produces({ MediaType.APPLICATION_JSON })
public Response getClusterName(#QueryParam("id") int id) {
ClusterCmdBean clusterCmdBean = new ClusterCmdBean();
String result = clusterCmdBean.getClusterNameForId(id);
return Response.ok(result).build();
}
}
Here is my bean class
public class ClusterCmdBean {
#HystrixCommand(groupKey = "ClusterCmdBeanGroup", commandKey = "getClusterNameForId", fallbackMethod = "defaultClusterName")
public String getClusterNameForId(int id) {
if (id > 0) {
return "cluster"+id;
} else {
throw new RuntimeException("command failed");
}
}
public String defaultClusterName(int id, Throwable e) {
return "No cluster - returned from fallback:" + e.getMessage();
}
}
Thanks for the help.
If you want to ensure you are setting the property, you can do that explicitly in the circuit annotation itself:
#HystrixCommand(commandProperties = {
#HystrixProperty(name = "execution.timeout.enabled", value = "false")
})
I would only recommend this for debugging purposes though.
Something that jumps out to me is that Javanica uses AspectJ AOP, which I have never seen work with new MyBean() before. I've always have to use #Autowired with Spring or similar to allow proxying. This could well just be something that is new to me though.
If you set a breakpoint inside the getClusterNameForId can you see in the stack trace that its being called via reflection (which it should be AFAIK)?
Note you can remove commandKey as this will default to the method name. Personally I would also remove groupKey and let it default to the class name.
I'm not able to figure out how to run a whole scenario before an other scenario, so that my test are not dependant on eachother.
I have this imaginary scenarios.
Scenario A
Given I have something
When I sumbit some data
I should see it on my webpage
Scenario B
Given SCENARIO A
When I delete the data
I should not see it on my webpage
When I run this scenario case, the software does not recognize Scenario A in scenario B, and ask me to create the step, like this...
You can implement missing steps with the snippets below:
#Given("^Registrere formue og inntekt$")
public void registrere_formue_og_inntekt() throws Throwable {
// Write code here that turns the phrase above into concrete actions
throw new PendingException();
}
You could either:
Use a Background to group all the steps that need to be executed before the different scenarii:
Background:
Given I have something
When I submit some data
Then I should see it on my webpage
Scenario: B
When I delete the data
Then I should not see it on my webpage
Group them as part of a step definition:
#Given("^Scenario A")
public void scenario_A() {
I_have_something();
I_submit_some_data();
I_should_see_it_on_my_page();
}
which you can then use like this:
Given Scenario A
When I delete the data
Then I should not see it on my webpage
Using this technique, you usually observe that some actions are constantly reused, and you may want to factor them out so that they can be reused across different step definitions; at that point, the Page Object pattern comes very handy.
Cucumber scenarios are supposed to be independent. A lot of work is done assuming and ensuring that independence. Trying to go against will be an obstacle course.
Having said that, you could create your custom implementation of the Cucumber JUnit runner. Having this custom implementation, and by looking at the source of the original runner, you can expose / wrap / change the internals to allow what you want. For example with the following runner:
public class MyCucumber extends Cucumber {
private static Runtime runtime;
private static JUnitReporter reporter;
private static List<CucumberFeature> features;
public MyCucumber(Class<?> clazz) throws InitializationError, IOException {
super(clazz);
}
#Override
#SuppressWarnings("static-access")
protected Runtime createRuntime(ResourceLoader resourceLoader,
ClassLoader classLoader, RuntimeOptions runtimeOptions)
throws InitializationError, IOException {
this.runtime = super.createRuntime(resourceLoader, classLoader, runtimeOptions);
this.reporter = new JUnitReporter(runtimeOptions.reporter(classLoader), runtimeOptions.formatter(classLoader), runtimeOptions.isStrict());
this.features = runtimeOptions.cucumberFeatures(resourceLoader);
return this.runtime;
}
public static void runScenario(String name) throws Exception {
new ExecutionUnitRunner(runtime, getScenario(name), reporter).run(new RunNotifier());
}
private static CucumberScenario getScenario(String name) {
for (CucumberFeature feature : features) {
for (CucumberTagStatement element : feature.getFeatureElements()) {
if (! (element instanceof CucumberScenario)) {
continue;
}
CucumberScenario scenario = (CucumberScenario) element;
if (! name.equals(scenario.getGherkinModel().getName())) {
continue;
}
return scenario;
}
}
return null;
}
}
You can setup your test suite with:
#RunWith(MyCucumber.class)
public class MyTest {
}
And create a step definition like:
#Given("^I first run scenario (.*)$")
public void i_first_run_scenario(String name) throws Throwable {
MyCucumber.runScenario(name);
}
It is a fragile customization (can break easily with new versions of cucumber-junit) but it should work.
Note: Cross-posted to ServerFault, based on comments.
Intro
I need to password protect some actions in my application, such as loading/saving files, clicking check-boxes, etc. This is a standard C# .Net 4.0, WinForms application which will run on Windows 7 in a corporate network.
I was about to roll my own very basic system (read obfuscation with wide open backdoors) with a text file of users/passwords/permissions (hashed and salted) until after some searching I found what looks like a
tantalizingly simple approach , but I'm having trouble finding a good tutorial on Roles that isn't about ASP.NET.
Question
So does anyone know of one or more tutorials that show me how to:
Create a Windows User/Group and give that User/Group a Role or Permission.
Note that I'm testing this from my company's networked laptop, but will deploy it on the customer's corporate network (Not sure if this is an issue, or how tricky this will get).
Create winforms/console app sample with even just a single method that prints "Hello World" if I'm authenticated or throws an exception if I'm not?
I've never done Network Admin or anything related and I keep reading about Active Directory and Local Users Vs Networked Users... I was hoping for an approach where I could build to an Interface and just ask Windows if the current user has permission ABC and not care too much about how Windows figured that out. Then I can make a concrete implementation for each Local/Network/ActiveDirectory/etc. use case as required (or if required... as I don't even know that right now).
Background
- read if interested, but not required to answer question
Just to make sure I'm going in the right direction here, basically I need/want to test this on my development PC to make sure it's going to have a good end-user experience for my customer. The problem is that currently they run an Auto-login script for each computer that runs my application and there are several different operators that use my application throughout the day. The customer wants password protection on certain features of my app and only provide that to certain operators. I have no problem fitting this in, as I've expected the request for a while, I just haven't ever programmed authentication before.
I think it's worthwhile to convince my customer to give each operator their own network account and assign whatever permissions they want to that operator or group, in case they need to fire somebody, change permissions, etc. It also means I just open several options for them and they can group those permissions however they see fit based on internal corporate policies, which I really shouldn't have to be worried about (but will be if I have to roll my own, as they're IT department knows almost nothing of my application).
From what I can tell it also makes my life a lot easier by not having to deal with hashing passwords and encryption, etc. and just handle which Role is required to click this or that button.
First of all, you'd have to determine, if you really want a simple role-based-authentication (you may want to read: http://lostechies.com/derickbailey/2011/05/24/dont-do-role-based-authorization-checks-do-activity-based-checks/)
If you're sure it's absolutely sufficient, you're already on the right way with the SO link you provided in your question. It's kind of confusing that there is no support of 'roles' by default in Windows, but there are groups. Groups can be local or remote (e.g. ActiveDirectory), so an admin could assign users to certain groups, that are specific for your application (for an example look here: http://msdn.microsoft.com/en-us/library/ms731200(v=vs.110).aspx)
One key is: You have to prepare your application's central principal, hence fill it with roles, supported for the current user.
Therefore, On the very startup of your application you then check the current active user and set your application wide principal and role(s). This may look like this (just a very simple example):
using System;
using System.Collections.Generic;
using System.Linq;
using System.Security;
using System.Security.Principal;
using System.Text;
using System.Threading;
namespace WindowsPrincipalTrial
{
public class Program
{
// you could also move these definitions to a config file
private static IDictionary<string, string> _groupRoleMappings = new Dictionary<string, string>()
{
{"MYAPPUSERGRP", MyRoles.Standard},
{"MYAPPSUPPORTGRP", MyRoles.Extended},
{"MYAPPADMINGRP", MyRoles.Admin},
};
private static void Main(string[] args)
{
var windowsId = WindowsIdentity.GetCurrent();
if (windowsId != null)
{
var allRoleNames = getGroupCorrespondingRoles(windowsId);
var newPrincipal = new GenericPrincipal(windowsId, allRoleNames);
Thread.CurrentPrincipal = newPrincipal;
}
else
{
throw new NotSupportedException("There must be a logged on Windows User.");
}
}
private static string[] getGroupCorrespondingRoles(WindowsIdentity id)
{
// you also could do this more elegant with LINQ
var allMappedRoleNames = new List<string>();
string roleName;
foreach (var grp in id.Groups)
{
var groupName = grp.Translate(typeof(NTAccount)).Value.ToUpper();
if (_groupRoleMappings.TryGetValue(groupName, out roleName))
{
allMappedRoleNames.Add(roleName);
}
}
return allMappedRoleNames.ToArray();
}
}
public static class MyRoles
{
public const string Standard = "standard_role";
public const string Extended = "extended_role";
public const string Admin = "admin_role";
}
}
Then your Application-Principal is set up.
Now you could check access in your code like this:
public void DoSomethingSpecial()
{
if (Thread.CurrentPrincipal.IsInRole(MyRoles.Extended))
{
// do your stuff
}
else
{
// maybe display an error
}
}
Or more drastically:
public void DoSomethingCritical()
{
var adminPermission = new PrincipalPermission(null, MyRoles.Admin);
adminPermission.Demand();
// do stuff
}
what is possible even declarative, as known from ASP.NET:
[PrincipalPermission(SecurityAction.Demand, Role=MyRoles.Admin)]
public void DoSomethingMoreCritical()
{
// do stuff
}
The ugly thing with the latter two examples is, that they throw exceptions, when the right role isn't hit.
So the mapping between roles and groups you have to do quite at the start of your app, according to the systems you want to use (local groups, AD groups, LDAP groups etc.).
If you, however, prefer authentication with actions and roles, after all, have a look at Windows Identity Foundation and Claims Based Authorization! There are already some ready-to-use frameworks out there (e.g. https://github.com/thinktecture/Thinktecture.IdentityModel).
UPDATE:
When it comes to activity based and thereby claims based authorization, I will try in short, how you could achieve it, by using Thinktecture's IdentityModel.
Generally that approach still uses roles internally, but has a kind of translation layer in between. Thinktecture already encapsulates many things needed. Authorization checks in code are then done via claim permissions. They are technically kind of request for an access to a certain resource. For the sake of simplicity I limit my example for actions only, by using one single default resource (since ClaimPermission doesn't accept an empty resource).
If you want to use action#resource pairs, you'd have to modify the code respectively.
At first you need a ClaimsAuthorizationManager
public class MyClaimsAuthorizationManager : ClaimsAuthorizationManager
{
private IActivityRoleMapper _actionToRolesMapper;
public MyClaimsAuthorizationManager(IActivityRoleMapper mapper)
{
_actionToRolesMapper = mapper;
}
public override bool CheckAccess(AuthorizationContext context)
{
if (context == null)
{
throw new ArgumentNullException("context");
}
try
{
var action = getActionNameFromAuthorizationContext(context);
var sufficientRoles = _actionToRolesMapper.GetRolesForAction(action)
.Select(roleName => roleName.ToUpper());
var principal = context.Principal;
return CheckAccessInternal(sufficientRoles, principal);
}
catch (Exception ex)
{
return false;
}
}
protected virtual bool CheckAccessInternal(IEnumerable<string> roleNamesInUpperCase, IClaimsPrincipal principal)
{
var result = principal.Identities.Any(identity =>
identity.Claims
.Where(claim => claim.ClaimType.Equals(identity.RoleClaimType))
.Select(roleClaim => roleClaim.Value.ToUpper())
.Any(roleName => roleNamesInUpperCase.Contains(roleName)));
return result;
}
// I'm ignoring resources here, modify this, if you need'em
private string getActionNameFromAuthorizationContext(AuthorizationContext context)
{
return context.Action
.Where(claim => claim.ClaimType.Equals(ClaimPermission.ActionType))
.Select(claim => claim.Value)
.FirstOrDefault();
}
}
As you may have guessed, IActivityRoleMapper is an interface for a class, that returns the names of all roles, that include permission for a given action.
This class is very individual and I guess you'll find your way implementing it, because it's not the point here. You could do it by hardcoding, loading from xml or from a database. Also you would have to change/extend it, if you wanted to you action#resource pairs for permission requests.
Then you'd have to change the code in main() method to:
using Thinktecture.IdentityModel;
using Thinktecture.IdentityModel.Claims;
using Microsoft.IdentityModel.Web;
private static void Main(string[] args)
{
var windowsId = WindowsIdentity.GetCurrent();
if (windowsId != null)
{
var rolesAsClaims = getGroupCorrespondingRoles(windowsId)
.Select(role => new Claim(ClaimTypes.Role, role))
.ToList();
// just if you want, remember the username
rolesAsClaims.Add(new Claim(ClaimTypes.Name, windowsId.Name));
var newId = new ClaimsIdentity(rolesAsClaims, null, ClaimTypes.Name, ClaimTypes.Role);
var newPrincipal = new ClaimsPrincipal(new ClaimsIdentity[] { newId });
AppDomain.CurrentDomain.SetThreadPrincipal(newPrincipal);
var roleMapper = new ActivityRoleMapper(); // you have to implement
// register your own authorization manager, so IdentityModel will use it per default
FederatedAuthentication.ServiceConfiguration.ClaimsAuthorizationManager = new MyClaimsAuthorizationManager(roleMapper);
}
else
{
throw new NotSupportedException("There must be a logged on Windows User.");
}
}
Finally you can check access this way:
public const string EmptyResource = "myapplication";
public void DoSomethingRestricted()
{
if (!ClaimPermission.CheckAccess("something_restricted", EmptyResource))
{
// error here
}
else
{
// do your really phat stuff here
}
}
Or again, with exceptions:
private static ClaimPermission RestrictedActionPermission = new ClaimPermission(EmptyResource, "something_restricted");
public void DoSomethingRestrictedDemand()
{
RestrictedActionPermission.Demand();
// play up, from here!
}
Declarative:
[ClaimPermission(SecurityAction.Demand, Operation = "something_restricted", Resource = EmptyResource)]
public void DoSomethingRestrictedDemand2()
{
// dostuff
}
Hope this helps.
I have an app I'm working on and it should save and load settings through an XML file (named Settings.txt)
Now, here's the code I use:
public class Settings
{
public bool Selected_64Bit { get; set; }
public bool Supported_64Bit { get; set; }
public bool FirstTime { get; set; }
}
static void SaveSettings(Settings settings)
{
var serializer = new XmlSerializer(typeof(Settings));
using (var stream = File.OpenWrite("settings.txt"))
{
serializer.Serialize(stream, settings);
}
}
static Settings LoadSettings()
{
if (!File.Exists("settings.txt"))
return new Settings();
var serializer = new XmlSerializer(typeof(Settings));
using (var stream = File.OpenRead("settings.txt"))
{
return (Settings)serializer.Deserialize(stream);
}
}
Now, I need to load the settings into a new Settings().
I found out that doing:
Settings [VAR] = new Settings()
will make a new Settings() with all false, but I want to LOAD the saved settings..
I'm confused and can't explain this to myself...
The final product should:
Check if settings.txt exists
If it does - LOAD SETTINGS into a new Settings called Setting (in my case).
If it doesn't - Make new settings and then save them.
I hope someone understood and can help me.
BTW - I'm not so good in C#, and I don't get the get\set thingy at all, as of return and other methods like that.. I know the basics and I'll be happy if I won't need more complicated techniques.
And if I must use more complicated techniques - please explain them deeply because I DO NOT KNOW.
As you have it set up, you'd need to do:
Settings mySettings = Settings.LoadSettings();
This will run your static LoadSettings method and return a Settings object.
As Matt already wrote
Settings mySettings = Settings.LoadSettings();
will do the job.
If you have a application you could use its settings as well. You get that settings by Properties.Settings.Default and in your project settings you can define some properties.
I've got a Silverlight enabled WCF web service set up and I'm connecting to it from my Silverlight application.
The Service is not written using the ASync pattern but Silverlight generates the async methods automatically.
I have a method that within my service that has a chance of throwing an exception I can catch this exception but I'm not sure of the best way of handling this exception, I've noticed that the event args of the completed method contain an error property.
Is is possible to set the value of this error property?
Example Method
public class service
{
[OperationContract]
public Stream getData(string filename)
{
string filepath = HostingEnvironment.MapPath(filename);
FileInfo fi = new FileInfo(filenpath);
try
{
Stream s = fi.Open(FileMode.Open);
return s;
}
catch (IOException e)
{
return null;
}
}
}
Silverlight Code
btnFoo_Click(object sender, RoutedEventArgs e)
{
ServiceClient svc = new ServiceClient();
svc.getDataCompleted += new EventHandler<getDataCompletedEventArgs>(getData_Completed);
svc.getDataAsync("text.txt");
}
void getData_Completed(object sender, getDataCompletedEventArgs e)
{
e.Error //how can i set this value on the service?
}
Finally if the service is offline or times out is there anyway to catch this exception before it reaches the UnhandledException method within App.xaml?
Thanks
Since silverlight is using services asyncronously you dont get a synchronous exception throw, but instead it is stored in e.Error property, that you need to check in your ServiceCallCompleted method.
To answer your question
how can i set this value on the service?
Simply throw an exception on server and it can be enough given several other conditions.
You may want to introduce FaultContract on your WCF service method, and throw FaultException<T> which is a common way to deal with errors in WCF.
However fault result in return code 500 and silverlight won't be able to get response with such status code and have access to Fault object, even if you add that attribute to service.
This can be solved using several approaches.
Use the alternative client HTTP stack: You can register an alternative HTTP stack by using the RegisterPrefix method. See below for an outline of how to do this. Silverlight 4 provides the option of using a client HTTP stack which, unlike the default browser HTTP stack, allows you to process SOAP-compliant fault messages. However, a potential problem of switching to the alternative HTTP stack is that information stored by the browser (such as authentication cookies) will no longer be available to Silverlight, and thus certain scenarios involving secure services might stop working, or require additional code to work.
Modify the HTTP status code: You can modify your service to return SOAP faults with an HTTP status code of 200, Silverlight 4 so that faults will be processed successfully. How to do this is outlined below. Note that this will make the service non-compliant with the SOAP protocol, because SOAP requires a response code in the 400 or 500 range for faults. If the service is a WCF service, you can create an endpoint behavior that plugs in a message inspector that changes the status code to 200. Then you can create an endpoint specifically for Silverlight consumption, and apply the behavior there. Your other endpoints will still remain SOAP-compliant.
Faults in silverlight
Creating and Handling Faults in Silverlight
OR
[DataContract]
public class MyError
{
[DataMember]
public string Code { get; set; }
[DataMember]
public string Message { get; set; }
[DataMember]
public DateTime Time { get; set; }
}
public class service
{
[OperationContract]
public Stream getData(string filename, out MyError myError)
{
myError = null;
string filepath = HostingEnvironment.MapPath(filename);
FileInfo fi = new FileInfo(filenpath);
try
{
Stream s = fi.Open(FileMode.Open);
return s;
}
catch (IOException e)
{
myError = new MyError() { Code = "000", Message = ex.Message, Time = DateTime.Now };
return null;
}
}
}
I wish successful projects