We're developing a JavaFX 2.x application, which needs to provide some GIS support. We've come to conclusion that using GoogleMaps via an embedded WebView is the quickest option. The problem with it is that every time our application starts, the corresponding JavaScript libraries are downloaded. This makes development very difficult as it takes a couple of second before anything interactive can be done on the WebView panel.
The first thing that comes to mind is to have some sort of caching like web browsers do in order to store the libraries and read them locally when needed. How can this be achieved with WebView? Are there any alternatives to caching in our case?
Thanx.
The WebView component doesn't provide caching of web resources out of the box. However, it does utilize the java.net stack for network communications. What this means is you can install your own URL Handler that talks to a cache and serves resources from that cache. For example, put something like this block in your main() method before the JavaFX launch call:
URL.setURLStreamHandlerFactory(new URLStreamHandlerFactory() {
public URLStreamHandler createURLStreamHandler(String protocol) {
if ( "http".equals(protocol) ) {
return new URLStreamHandler() {
protected URLConnection openConnection(URL u) throws IOException {
if ( isCached(u) ) {
return new CachedStreamConnection(u);
}
return new MyURLConnection(u);
}
};
}
// Don't handle a non-http protocol, so just return null and let
// the system return the default one.
return null;
}
});
Of course the devil is in the details. You should take the cache policies returned by the HTTP headers (like ETags) into consideration when storing a resource in your cache. Another consideration is HTML meta tags. Here is a good resource on caching.
You may also want to consider a cookie management system to complement this cache management system.
Related
I'm rather new to Blazor, but I am currently trying to get access to some classes from within a class library that I've created and deployed as a Nuget package. As background, the Nuget package is an Api library, which allows me to talk to a webservice (I don't know if this is relevant or not). However, every time I go to the page where I'm testing, the page never loads and instead I left looking at the browser loading circle until I navigate away or close the application. During my testing here, it seems like it's the #inject call of my interface into the Blazor component which is causing the issue as when I remove it and try to load the page normally, the page does so.
So to demonstrate what I have setup, here is where I've added the Singletons to the DI:
builder.Services.AddSingleton<IApiConfigHelper, ApiConfigHelper>();
builder.Services.AddSingleton<IApiHelper, ApiHelper>();
builder.Services.AddSingleton<ISystemEndpoint, SystemEndpoint>();
Then on the blazor page, I have the following declarations at the top of my page:
#using Library.Endpoints
#using Library.Models
#page "/"
#inject ISystemEndpoint _systemEndpoint
Now I am leaning towards is this something to do with the Nuget package and using it with DI. I have tested the library away from this project (In a console application) and can confirm it's working as it should.
I have also created a local class library as a test to, to see if I could inject a data access class into the page and I can confirm that this works without an issue, which suggests to me that DI is working, just not with my Nuget package.
I did have a look into CORS, given that the Nuget package is accessing an external domain, and setup the following simple CORS policy in the app:
builder.Services.AddCors(policy =>
{
policy.AddPolicy("OpenCorsPolicy", opt =>
opt.AllowAnyOrigin()
.AllowAnyHeader()
.AllowAnyMethod());
});
Which is added to the app after the AddRouting call like so:
app.UseCors("OpenCorsPolicy");
However again, this wasn't the solution so if anyone is able to point me in the right direction with where I may be going wrong with this or offer any advice, I would be most grateful.
EDIT 1 - Provides details #mason queried
Regarding SystemEndpoint, the constructor is being injected with 2 things, as below:
public SystemEndpoint(IApiHelper apiHelper, IOptions<UriConfigModel> uriOptions)
{
_apiHelper = apiHelper;
_uriOptions = uriOptions.Value;
}
My Nuget Library is dependant on the following:
Azure.Identity
Azure.Security.KeyVault.Secrets
Microsoft.AspNet.WebApi.Client
Microsoft.Extensisons.Options.ConfigurationExtensions
EDIT 2 - Doing some further testing with this I have added a simple Endpoint class to my Nuget library, which returns a string with a basic message, as well as returning the values of the 2 UriConfig properties as below. I added this test to 1) sanity check that my DI was working correctly, and 2) check the values that are being assigned from appsettings to my UriConfig Object.
public class TestEndpoint : ITestEndpoint
{
private readonly IOptions<UriConfigModel> _uriConfig;
public TestEndpoint(IOptions<UriConfigModel> uriConfig)
{
_uriConfig = uriConfig;
}
public string TestMethod()
{
return $"You have successfully called the test method\n\n{_uriConfig.Value.Release} / {_uriConfig.Value.Version}";
}
}
However when adding in the dependency of IApiHelper into the Ctor, the method then breaks and fails to load the page. Looking into ApiHeloer, the Ctor has a dependency being injected into it of IApiConfigHelper. Looking at the implementation, the Ctor of ApiConfigHelper is setting up the values and parameters of the HttpClient that should make the REST calls to the external Api.
Now I believe what is breaking the code at this point is a call I'm making to Azure Key Vault, via REST, to pull out the secret values to connect to the Api. The call to KeyVault is being orchestrated via the following method, making use of the Azure.Security.KeyVault.Secrets Nuget Package, however I assume that at the heart of it, it's making a REST call to Azure on my behalf:
private async Task<KeyVaultSecret> GetKeyVaultValue(string secretName = "")
{
try
{
if (_secretClient is not null)
{
var result = await _secretClient.GetSecretAsync(secretName);
return result.Value;
}
}
catch (ArgumentException ae)
{
Console.WriteLine(ae.Message);
}
catch (Azure.RequestFailedException rfe)
{
Console.WriteLine(rfe.Message);
}
return new(secretName, "");
}
So that's where I stand with this at the moment. I still believe it could be down to CORS, as it seems to be falling over when making a call to an external service / domain, but I still can say 100%. As a closing thought, could it be something as simple as when I call call the above method, it's not being awaited????
So after persisting with this it seems like the reason it was failing was down to "awaiting" the call to Azure KeyVault, which was happening indirectly via the constructor of ApiConfigHelper. The resulting method for getting KeyVault value is now:
private KeyVaultSecret GetKeyVaultValue(string secretName = "")
{
try
{
if (_secretClient is not null)
{
var result = _secretClient.GetSecret(secretName);
if (result is not null)
{
return result.Value;
}
}
}
catch (ArgumentException ae)
{
Console.WriteLine(ae.Message);
}
catch (Azure.RequestFailedException rfe)
{
Console.WriteLine(rfe.Message);
}
return new(secretName, "");
}
I am now able to successfully make calls to my library and return values from the Api it interacts with.
I can also confirm that this IS NOT a CORS issue. Once I saw that removing the await was working, I then removed the CORS policy declarations from the service and the app in my Blazor's start-up code and everything continued to work without an issue.
As a final note, I must stress that this is only seems an issue when using the library with Blazor (possibly webApi projects) as I am able to use the library, awaiting the Azure call just fine in a console application.
Using VB.NET asmx project, which is hosted behind SSL offload, I need to change the generated WSDL to show https for the soap:address.
from: <soap:address location="http://example.com/example.asmx"/>
to: <soap:address location="https://example.com/example.asmx"/>
preferably outside of code so we can influence in the build process.
It depends what system are you using for generating the wsdl.
You shared that you are using VB.NET but it does not narrow down enough to answer your question a 100%. If you can show some code then we could help hopefully. Also as far as I remember, the location in the WSDL file is the same as the client is accessing it (the URL where it reaches). Meaning that as the offloading happens elsewhere the location could always be http.
Without further information I see three options for you:
Configure the TLS offloader to redirect the queries from http to httpS. (This is also a recommended setting from a security point of view.)
Where the offloading is happening use a solution to replace the content of the response. (This has the advantage of being specific to the environment.)
Use self singed certificate on the internal application as well, and therefore the address will be generated correctly. (This could be a bit tougher nut to crack, but has the benefit of not being dependent on other configuration and having to modify that configuration for every environment from development to live.)
In c# it could be done in code https://learn.microsoft.com/en-us/archive/blogs/kaevans/modify-a-web-services-wsdl-using-a-soapextensionreflector and is qite complicated. If you have a developer machine, then you need to use TLS as well... but here you go:
using System;
using System.Web.Services.Description;
namespace Msdn.Web.Services.Samples
{
public class HttpsReflector : SoapExtensionReflector
{
public override void ReflectMethod()
{
//no-op
}
public override void ReflectDescription()
{
ServiceDescription description = ReflectionContext.ServiceDescription;
foreach (Service service in description.Services)
{
foreach (Port port in service.Ports)
{
foreach (ServiceDescriptionFormatExtension extension in port.Extensions)
{
SoapAddressBinding binding = extension as SoapAddressBinding;
if (null != binding)
{
binding.Location = binding.Location.Replace("https://", "https://");
}
}
}
}
}
}
}
So, I wrote a Nuget that allows dev in my company to quickly setup authorization using OIDC. Part of that, of course, is handing off the authentication step to a browser so I'm simply invoking Browse.OpenAsync with LaunchMode = BrowserLaunchMode.SystemPreferred. I also set up a HTTP listener that awaits the ahtority's authorization code callback. All works find but the browser window is of course still sitting at the top, hiding the initiating app.
I do realise I can use deep linking to simply "call up" the app again but that has two implications I would like to avoid: The need to register custom URI schema with the mobile OS and, above all, the need to register that (custom) callback URI with my company's API management system (which doesn't like anything but "http" or "https" URI schemes). Those requirements makes it more complicated for our devs to get started and, like I mentioned, it doesn't work very well with our API management system, so I'm looking for a simpler solution.
For iOS I can simply fetch the key window's view controller and dismiss it, like so:
async Task<Outcome> IPlatformService.TryCloseTopWindowAsync(bool isModalWindow, bool animated)
{
var window = UIApplication.SharedApplication.KeyWindow;
var viewController = window?.RootViewController;
if (viewController is null)
return Outcome.Fail("Couldn't obtain top window view controller");
try
{
if (isModalWindow)
{
viewController.DismissModalViewController(animated);
return Outcome.Success();
}
await viewController.DismissViewControllerAsync(animated);
return Outcome.Success();
}
catch (Exception ex)
{
return Outcome.Fail(ex);
}
}
Unfortunately, I'm not very good with Android's (Java based) APIs so I'm wondering if it's possible to do something similar here? Can I get the top app (activated by my own app) and dismiss it? If so; how?
We are currently working on the finishing touches of an application which uses Phonegap and have hit some issues with the Blackberry port.
So far, we've been reviewing the content available online and can't find a really finale answer to this. Seems like the "right" way to make and oauth authentication process for either Twitter, Facebook or Foursquare would be to use the ChildBrowser plugin, instantiate a window and then use that to handle the process.
Rightly so, there seems to be a lack of a ChildBrowser plugin for Blackberry. We've been looking so far at a couple of private projects on Github that look like they build/use that capability but we are not sure on how to control the created window.
Most (or all?) of those plugins refer to invoking the native Blackberry browser to handle the URLS, but then how would be manage to work on the callbacks, get the tokens and close the windows since it's another process.
For example, we have this concept code:
function openWindow() {
if (typeof blackberry !== 'undefined') {
app_id = SOMETHING_HERE;
redirect = 'http://www.facebook.com/connect/login_success.html';
url = 'https://graph.facebook.com/oauth/authorizeclient_id='+app_id+'&redirect_uri='+redirect+'&display=touch&scope=publish_stream';
var args = new blackberry.invoke.BrowserArguments(url);
blackberry.invoke.invoke(blackberry.invoke.APP_BROWSER, args);
}
}
Which works for opening the URL, but that's it. Is there a way to get a handle on the window and inject some listener to events? What should be our correct approach?
Thanks!
I am not PhoneGap user, but we did have to handle a very similar scenario - native app invokes the mobile browser to prompt the oAuth flow and then be able to handle a callback to the aative app.
This is possible on the BlackBerry using the BrowserContentProviderRegistry API. You can register your app to be invoked whenever a particular MIME type is returned to the browser. Sounds complicated but its fairly straightforward when all the pieces are in play.
Here is the rough flow -
Native app invokes browser to the oAuth page. This is part is easy and seems like you got this part.
The oAuth redirect needs to go to a URL that you can control. Something like http://mycompany.com/oAuthRedirectHandler.asp.
The oAuthRedirectorHandler.asp has simple code like this (we chose classic ASP but this can be done in PHP or any language, you can also ignore the Android block below) -
<html><body>
<h1>Redirect page</h1>
If you are not re-directed, please open the application manually.
<% strUA = Request.ServerVariables("HTTP_USER_AGENT")
if (InStr(strUA, "BlackBerry")) then
Response.Write("Opening appplication on BlackBerry")
Response.ContentType="application/x-MyCustomApp"
elseif (InStr(strUA, "Android")) then
Response.Write("Opening appplication on Android")
Response.Redirect("MyCustomApp://mycompany.com")
end if %>
</body> </html>
In your BlackBerry code you want a new BrowserContentProvider like this -
final class CustomBrowserProvider extends BrowserContentProvider{
String[] ACCEPT = new String[]{"application/x-MyCustomApp};
String appName;
CustomBrowserProvider(String appName){
this.appName = ApplicationDescriptor.currentApplicationDescriptor().getModuleName();
//cache this appName from the constructor in the invocation code below.
}
public String[] getSupportedMimeTypes() { return ACCEPT;}
public String[] getAccept(RenderingOptions context){return ACCEPT;}
public BrowserContent getBrowserContent( BrowserContentProviderContext context) throws RenderingException {
//this is where the callback happens
//this is happening in a separate process, raise your main app here using the appName that got passed in
//I dont have a sanitized ready to go sample to post here on how to do this, but not too complicated
//as a hint use the ApplicationDescriptor and CodeModuleManager classes
return null;
}
}
Now, in your application initialization, register this new BrowserPlugin like this -
BrowserContentProviderRegistry converterRegistry = BrowserContentProviderRegistry.getInstance();
converterRegistry.register(new CustomBrowserProvider());
Hope this helps. This has worked pretty well for us. The one downside we've had here is that when the user returns to the browser app, they are left with an empty page and there is no good way to close that in the BB.
I am creating a site which will be accessible via mobile and desktop devices. So I want to create 2 views of my application. My action code and everything else in the backend (manageers, DAOs) is same. Just JSP changes for both.
How I can do this via Struts 2?
In struts there are many way to obtain the same thing.
In this case, the one I prefer is:
You could write an interceptor that changes the return code based on the user-agent of
the client, such that there would be versions for PC and mobile of each jsp.
In your configuration you need to have all the result codes for all jsp (or you could simply define the result through the wildcard mapping).
For example: change the result code from "success" to "mobile_success". In case you want map both results in the same jsp you can map, as I said before, in this way
<result name="*success">
not sure whether there is library for automating such task for struts 2. but if there is, using such libraries might be better
anyway, here is the theory. every browser has its own "signature" written in the request header, called "User-Agent". different browser (supposedly) has different user agent. for example, my firefox user agent is as following:
Mozilla/5.0 (Windows NT 6.0; rv:5.0) Gecko/20100101 Firefox/5.0 FirePHP/0.5
basically, by detecting the user agent, you can know what browser is used to access your site. the list of mobile browser user agents can be found in http://www.zytrax.com/tech/web/mobile_ids.html
if i'm not wrong, you can retrieve the user agent in server by httpServletRequest.getHeader("User-Agent"); (correct me if i'm wrong)
you can then create an interceptor which will decide whether a client is from mobile or from desktop. that interceptor can return different result for different client type. for example, if the client is desktop, you can return "successDesktop" and if the client is mobile, you can return "successMobile".
well, hopefully someone else can come up with (far) easier solution
I am currently trying to solve this very same problem. A framework would be nice, and I'm all ears if anyone has tested and approved one. That said, I can't find anything mature enough for me to be justify moving from Struts for the mobile view.
My best solution currently is to create actions for each of the parts of my full page which will be displayed on full browsers. Then to reuse those actions to display page segments on the mobile side.
I found trying to make one page look right for a desktop browser and a mobile browser simultaneously was not a sustainable approach.
jQuery mobile looks like a very promising library for styling the elements retrieved by struts.
So while it is surely possible to cram both versions of the site into one action I think taking the time to create small reusable actions that result in jsp snippits will pay off as your app scales.
Here are some possibilities for the near future:
(I can't add these as links as I don't have enough reputation...you'll have to add the 'http://www.')
Struts2 jQuery Mobile Project homepage: http://code.google.com/p/struts2-jquery/
Struts2 jQuery Mobile project: code.google.com/p/struts2-jquery/downloads/detail?name=struts2-jquery-mobile-showcase-3.1.1.war
an example of struts2 jQuery Mobile: weinfreund.de/struts2-jquery-mobile-showcase/index.action
#fajrian - using 'user agent' to determine a browser type could become a real pain as more and more mobile and desktop browsers are released. A better approach would be to determine whether to display a mobile version or full version based on the window's dimensions. A perfect example.
edit - Check out CSS3 media queries.
As Maurizio said you could use interceptors. Here is what I found.... http://www.benmccann.com/blog/struts-2-tutorial-interceptors/
This works for me and should basically get round the problem. You do need to know at least part of the user agent strings though:
public class MobileInterceptor extends AbstractInterceptor {
private static final String RESULT_CODE_SUFFIX_MOBILE = "mobile";
private static final String REQUEST_HEADER_ACCEPT = "Accept";
private static final String[] MOBILE_BROWSER_UAS = {"iPhone OS","Android","BlackBerry","Windows Phone"};
public String intercept(ActionInvocation invocation) throws Exception {
invocation.addPreResultListener(new PreResultListener() {
public void beforeResult(ActionInvocation invocation, String resultCode) {
// check if a wireless version of the page exists
// by looking for a wireless action mapping in the struts.xml
Map results = invocation.getProxy().getConfig().getResults();
System.out.println("Results:"+results.toString());
if(!results.containsKey(resultCode + RESULT_CODE_SUFFIX_MOBILE)) {
return;
}
// send to mobile version if mobile browser is used
final String acceptHeader = ServletActionContext.getRequest().getHeader(REQUEST_HEADER_ACCEPT);
//Get User Agent String
String userAgent = ServletActionContext.getRequest().getHeader("User-Agent");
System.out.println("UA: "+userAgent);
//Boolean to indicate whether to show mobile version
boolean showMobileVersion = false;
//Run through each entry in the list of browsers
for(String ua : MOBILE_BROWSER_UAS){
if(userAgent.toLowerCase().matches(".*"+ua.toLowerCase()+".*")){
showMobileVersion = true;
}
}
if(showMobileVersion) {
invocation.setResultCode(resultCode + RESULT_CODE_SUFFIX_MOBILE);
}
}
});
return invocation.invoke();
}