I want to be able to replace and add some classes to an already running JVM. I read that I need to use CreateRemoteThread, but I don't completely get it. I read this post on how to do it (Software RnD), but I can't figure out what it does and why. Besides that, it only introduces new classes, but doesn't change existing ones. How can I do it with C++?
You don't even need CreateRemoteThread - there is an official way to connect to remote JVM and replace loaded classes by using Attach API.
You need a Java Agent that calls Instrumentation.redefineClasses.
public static void agentmain(String args, Instrumentation instr) throws Exception {
Class oldClass = Class.forName("org.pkg.MyClass");
Path newFile = Paths.get("/path/to/MyClass.class");
byte[] newData = Files.readAllBytes(newFile);
instr.redefineClasses(new ClassDefinition(oldClass, newData));
}
You'll have to add MANIFEST.MF with Agent-Class attribute and pack the agent into a jar file.
Then use Dynamic Attach to inject the agent jar into the running VM (with process ID = pid).
import com.sun.tools.attach.VirtualMachine;
...
VirtualMachine vm = VirtualMachine.attach(pid);
try {
vm.loadAgent(agentJarPath, options);
} finally {
vm.detach();
}
A bit more details in the article.
If you insist on using C/C++ instead of Java API, you may look at my jattach utility.
Related
The spring-cloud-function-deployer examples all show the deployed function being loaded on startup i.e. the ApplicationContext is started with the necessary properties, pointing at the packaged jar to load.
Is there a way to call the deployer programatically at runtime, instead of relying on the auto-configuration? In case I want to deploy the function sometime after the application context has started, or if I want to deploy multiple functions from the same jar etc.
Also is there a way to undeploy any loaded functions, or is this simple as removing the function from the catalog?
as stated in the GH response, you absolutely can deploy functions at runtime.
String[] args = new String[] {
"--spring.cloud.function.location=target/it/bootapp/target/bootapp-1.0.0.RELEASE-exec.jar",
"--spring.cloud.function.definition=uppercase" };
ApplicationContext context = SpringApplication.run(DeployerApplication.class, args);
FunctionCatalog catalog = context.getBean(FunctionCatalog.class);
Function<String, String> function = catalog.lookup("uppercase");
// use the function
You can see sample deployments here and the corresponding test.
I am migrating from Jetty 8.1.17 to Jetty 9.3.9. Our application embeds Jetty. Previously we had a single XML configuration file jetty.xml which contained everything we needed.
I felt that with Jetty 9.3.9 it would be much nicer to use the modular approach that they suggest, so far I have jetty.xml, jetty-http.xml, jetty-https.xml and jetty-ssl.xml in my $JETTY_HOME/etc; these are pretty much copies of those from the 9.3.9 distribution. This seems to work well when I use start.jar but not through my own code which embeds Jetty.
Ideally I would like to be able to scan for any jetty xml files in the $JETTY_HOME/etc folder and load the configuration. However for embedded mode I have not found a way to do that without explicitly defining the order that those files should be loaded in, due to <ref id="x"/> dependencies between them etc.
My initial attempt is based on How can I programmatically start a jetty server with multiple configuration files? and looks like:
final List<Object> configuredObjects = new ArrayList();
XmlConfiguration last = null;
for(final Path confFile : configFiles) {
logger.info("[loading jetty configuration : {}]", confFile.toString());
try(final InputStream is = Files.newInputStream(confFile)) {
final XmlConfiguration configuration = new XmlConfiguration(is);
if (last != null) {
configuration.getIdMap().putAll(last.getIdMap());
}
configuredObjects.add(configuration.configure());
last = configuration;
}
}
Server server = null;
// For all objects created by XmlConfigurations, start them if they are lifecycles.
for (final Object configuredObject : configuredObjects) {
if(configuredObject instanceof Server) {
server = (Server)configuredObject;
}
if (configuredObject instanceof LifeCycle) {
final LifeCycle lc = (LifeCycle)configuredObject;
if (!lc.isRunning()) {
lc.start();
}
}
}
However, I get Exceptions at startup if jetty-https.xml is loaded before jetty-ssl.xml or if I place a reference in jetty.xml to an object from a sub-configuration jetty-blah.xml which has not been loaded first.
It seems to me like Jetty manages to do this okay itself when you call java -jar start.jar, so what am I missing to get Jetty to not care about what order the config files are parsed in?
Order is extremely important when loading the Jetty XML files.
That's the heart of what the entire start.jar and its module system is about, have an appropriate set of properties, the server classpath is sane, and ensuring proper load order of the XML.
Note: its not possible to have everything in ${jetty.home}/etc loaded at the same time, as you will get conflicts on alternate implementations of common technologies (something start.jar also manages for you)
I would like to consume a Soap Service provided by DHL. You can find the wsdl here: https://wsbexpress.dhl.com/sndpt/expressRateBook?WSDL
Therefore I created a new ClassLibrary in Visual Studio 2015 targeting .net framework 4.5.
Then I added a Web Reference to the created project by providing the wsdl address. I generated a proxy file with all types and ports in it but my first problem is, that the generated Service extends from System.Web.Services.Protocols.SoapHttpClientProtocol. As I read in recent posts it is not possible to get the wsse header to that proxy. Some posts advise to add wse but it seems wse is not supported by newer Visual Studio versions.
I tried to generate my proxy by svcutil. After that I added the generated .cs file to the project and copied the content of the generated config file to app.config. (of cause I removed the web reference)
Now the Service class extends System.ServiceModel.ClientBase. (I thought the generator in VS uses svctool internally. If microsoft want people to use wcf why does the generator generate non-wcf proxy files.
I also created a nunit testproject which should test my service, but If I use the version with the svcutil generated version I get an error. I try to translate it to english as the error is displayed in german:
Could not find a default endpoint element which points to the service contract. As I figured out this is because the proxy is in its own class library and therefor doesn't really have an app.config. But my test project is a class library too.
What would be the actual way to consume a web service which needs ws security Username/Password auth these days?
You can add the Web Reference in compatibility mode (I am guessing you are doing so). If you are not adding the reference in compatibility mode, do the following:
Right click on references Add Service Reference-> Advanced -> Add Web Reference (Below the compatibility section), type the URL of the WS and add the reference.
The WSE2.0 extensions are available as a Nuget Package at:
https://www.nuget.org/packages/Microsoft.Web.Services2/
Install the nuget package on the package manager console running the following nugget command:
Install-Package Microsoft.Web.Services2
After you installed the nuget package, you need to make sure your project is referencing the following DLL's:
System.Web
System.Web.Services
Microsoft.Web.Services2 (This will be added after you install the nuget package)
In order to use the WSE2.0 extensions, you need to actually modify the Proxy class that was created when you added the WebReference to inherit from "Microsoft.Web.Services2.WebServicesClientProtocol" instead of "System.Web.Services.Protocols.SoapHttpClientProtocol". Be aware that if you update the WebReference, the Proxy class will inherit againfrom SoapHttpClientProtocol.
Add the following using clauses to the code consuming the Proxy class:
using Microsoft.Web.Services2;
using Microsoft.Web.Services2.Security;
using Microsoft.Web.Services2.Security.Tokens;
After you make this changes, you code should look something like this:
var token = new UsernameToken("theUser", "thePassword", PasswordOption.SendHashed);
var serviceProxy = new ExpressRateBook.gblExpressRateBook();
SoapContext requestContext = serviceProxy.RequestSoapContext;
requestContext.Security.Timestamp.TtlInSeconds = 60;
requestContext.Security.Tokens.Add(token);
//The rest of the logic goes here...
I added the screenshot down below for your reference:
NOTE: I was unable to test the code since I am unfamiliar with the actual methods that you need to consume, the code displayed is just an example of what I saw in the proxy class, update it according to your needs. It should work fine if you follow the steps described before. Check the following link for more detailed instructions:
https://msdn.microsoft.com/en-us/library/ms819938.aspx
You can configure you Service Reference to add the Security Header as AW Rowse describes at http://cxdeveloper.com/article/implementing-ws-security-digest-password-nonce-net-40-wcf:
private void Configure()
{
System.Net.ServicePointManager.ServerCertificateValidationCallback = (senderX, certificate, chain, sslPolicyErrors) => { return true; };
defaultBinding = new BasicHttpBinding
{
Security =
{
Mode = BasicHttpSecurityMode.Transport,
Transport =
{
ClientCredentialType = HttpClientCredentialType.Digest
}
}
};
defaultToken = new UsernameToken(UserName, Password, PasswordOption.SendHashed);
defaultSecurityHeader = MessageHeader.CreateHeader(
"Security",
"http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd",
defaultToken.GetXml(new XmlDocument())
);
}
And create you client/proxy like this:
public consulta_informacao_respttClient CriaConsultaClinicaClient()
{
var client = new consulta_informacao_respttClient(defaultBinding, new EndpointAddress("https://resqa.homologacao.unimed.coop.br/chs-integration-external-services-ptu-clinical/proxy-services/execute-query/execute-query-proxy-service"));
client.ClientCredentials.UserName.UserName = UserName;
client.ClientCredentials.UserName.Password = Password;
var scope = new OperationContextScope(client.InnerChannel);
OperationContext.Current.OutgoingMessageHeaders.Add(defaultSecurityHeader);
return client;
}
The properties you will need to create in your class are:
private BasicHttpBinding defaultBinding;
private UsernameToken defaultToken;
private MessageHeader defaultSecurityHeader;
You won't need to configure anything in app/web.config.
I'm wondering whether I could replicate the forceKeyspaceFlush() function found in the nodetool utility from the C/C++ driver of Cassandra.
The nodetool function looks like this:
public class Flush extends NodeToolCmd
{
#Arguments(usage = "[<keyspace> <tables>...]", description = "The keyspace followed by one or many tables")
private List<String> args = new ArrayList<>();
#Override
public void execute(NodeProbe probe)
{
List<String> keyspaces = parseOptionalKeyspace(args, probe);
String[] tableNames = parseOptionalTables(args);
for (String keyspace : keyspaces)
{
try
{
probe.forceKeyspaceFlush(keyspace, tableNames);
} catch (Exception e)
{
throw new RuntimeException("Error occurred during flushing", e);
}
}
}
}
What I would like to replicate in my C++ software is this line:
probe.forceKeyspaceFlush(keyspace, tableNames);
Is it possible?
That's an unusual request, primarily because Cassandra is designed to be distributed, so if you're executing a query, you'd need to perform that blocking flush on each of the (potentially many) replicas. Rather than convince you that you don't really need this, I'll attempt to answer your question - however, you probably don't really need this.
Nodetool is using the JMX interface (on tcp/7199) to force that flush - Your c/c++ driver talks over the native protocol (on tcp/9042). At this time, flush is not possible via the native protocol.
Work around the limitation, you'd need to either exec a jmx-capable commandline utility (nodetool or other), implement a JMX client in c++ (it's been done), or extend the native protocol. None of those are particularly pleasant options, but I imagine executing a jmx CLI utility is significantly easier than the other two.
Forgive me if this is a dumb question, I unfortunately have an assignment due! I am running apache axis under tomcat and need to deploy a simple web service class, see below.
I installed the counter file below as "MyCounter.jws" in the /tomcat/webapps/axis/ folder. Tomcat finds it and makes a corresponding MyCounter.xml. I use WSDL2Java on the XML file and client calls seem to work, but internal state is not saved:
Every time I call MyCounter.call from the client side, the return value is always 1. It seems the constructor is always called before the method call. How can I make it so the mycounter integer persists across requests?
public class MyCounter
{
int mycounter;
public MyCounter()
{
mycounter = 0;
}
public int call()
{
mycounter++;
return mycounter;
}
}
I think persisting is maybe the wrong word, I think what you mean is that the Java Class is not instantiated every time you call the service.
See: https://axis.apache.org/axis/java/user-guide.html#Scoped_Services
So you would need to change the Service definition yo achieve this.
I don't think that with the JWS files you will be able to configure the session scope. As the docs say:
https://axis.apache.org/axis/java/user-guide.html#JWS_Java_Web_Service_Files_-_Instant_Deployment
Quote:
Important: JWS web services are intended for simple web services. You
cannot use packages in the pages, and as the code is compiled at run
time you can not find out about errors until after deployment.
Production quality web services should use Java classes with custom
deployment.
So if you want to use such features you should consider using some of the other ways Axis offers to setup a WebService.
Also I would strongly recommend using Axis2 instead of Axis1:
http://axis.apache.org/axis2/java/core/
Axis1 can be quite complicated with the WSDD files to setup. Apart from Axis1 no more actively developed/maintained.