An application is using JBoss 4.2.2, and I have found it necessary to call listThreadDump(), and I expect it is in ServerInfo.
I am thinking the jar I need to find this information is jboss-jmx.jar.
So, how do I programmatically duplicate what is done by calling something similar to http://localhost:8080/jmx-console/HtmlAdaptor?action=invokeOpByName&name=jboss.system:type=ServerInfo&methodName=listThreadDump?
This is how I have accessed the ServerInfo MBean. I'm using JBoss AS 5.1, but this method should be the same.
To call listThreadDump(), you can invoke() the method on the ServerInfo MBean using an MBeanServer instance.
Additionally, you can access attributes of MBeans using the same MBeanServer.
Sample code:
// imports
import javax.management.MBeanServer;
import javax.management.ObjectName;
import org.jboss.mx.util.MBeanServerLocator;
try {
MBeanServer server = MBeanServerLocator.locate();
ObjectName name = new ObjectName("jboss.system:type=ServerInfo");
// invoke the listThreadDump method and capture its output
String threadDumpHtml = (String) server.invoke(name, "listThreadDump", null, null);
// access a simple attribute of the ServerInfo object
String jvmName = (String) server.getAttribute(name, "JavaVMName");
} catch (Exception e) {
// Ideally catch the 3 exact exceptions
}
Finally, I find it handy when MBeans expose an 'instance' attribute, so you can then access the object directly (CastToType) server.getAttribute(name, "instance") instead of always going through the MBeanServer. For example, when using JMS, the ServerPeer instance is nice to have as you can get message counters on your queues and topic subscribers.
Related
I wrote some codes that used java Api of GraphDatabaseService to access an embedded database before. But now I want to switch the database to a remote one, so I have to use Driver and Session class to write and run cyphers. I don't like cyphers and I don't want to change the old codes.
So I'm looking for a way so that I can get GraphDatabaseService from Driver, but none is found.
I think a possible way is to make up a GraphDataBaseService delegate that wraps a Driver and converts Api calls to cyphers. Is that feasible? Is there already some libraries which can do this?
You won't get a direct equivalent of GraphDatabaseService since that's the embedded API.
You can however run Cypher queries like this:
var driver = GraphDatabase.driver(
"some://address",
AuthTokens.basic("username", "password")
);
// [...]
try (var session = driver.session() {
return session.writeTransaction(tx -> {
Result result = tx.run(
"CYPHER QUERY",
Map.of(/* query parameters */)
);
// do something with result
});
}
// [...]
driver.close(); // (driver is usually a singleton - closes when application shuts down)
I tried to make a project to solve this problem by wrapping Driver to GraphDatabaseService.
I am new to grails and while working with Spring Security LDAP plugin it was identified that it accepts the ldap server password in plain text only. The task in hand is to pass an encrypted password which is decrypted before it is consumed by the plugin during its initialization phase.
I have already searched for all possible blogs and stackoverflow questions but could not find a way to extend the main plugin class to simply override the doWithSpring() method so that i can simply add the required decryption logic for the Ldap server password. Any help here will be appreciated.
I have already seen and tried jasypt plugin but it also does not work well if the password is stored in some external file and not application yml. So I am looking for a solution to extend the Spring security plugin main class, add the required behavior and register the custom class.
EDIT
Adding the snippet from Grails LDAP Security plugin, which I am trying to override. So If i am successfully able to update the value of securityConfig object before the plugin loads, the purpose is solved.
Some snippet from the plugin:
def conf = SpringSecurityUtils.securityConfig
...
...
contextSource(DefaultSpringSecurityContextSource, conf.ldap.context.server) { // 'ldap://localhost:389'
authenticationSource = ref('ldapAuthenticationSource')
authenticationStrategy = ref('authenticationStrategy')
userDn = conf.ldap.context.managerDn // 'cn=admin,dc=example,dc=com'
**password = conf.ldap.context.managerPassword // 'secret'**
contextFactory = contextFactoryClass
dirObjectFactory = dirObjectFactoryClass
baseEnvironmentProperties = conf.ldap.context.baseEnvironmentProperties // none
cacheEnvironmentProperties = conf.ldap.context.cacheEnvironmentProperties // true
anonymousReadOnly = conf.ldap.context.anonymousReadOnly // false
referral = conf.ldap.context.referral // null
}
ldapAuthenticationSource(SimpleAuthenticationSource) {
principal = conf.ldap.context.managerDn // 'cn=admin,dc=example,dc=com'
**credentials = conf.ldap.context.managerPassword // 'secret'**
}
You don't need to override the doWithSpring() method in the existing plugin. You can provide your own plugin which loads after the one you want to affect and have your doWithSpring() add whatever you want to the context. If you add beans with the same name as the ones added by the other plugin, yours will replace the ones provided by the other plugin as long as you configure your plugin to load after the other one. Similarly, you could do the same think in resources.groovy of the app if you don't want to write a plugin for this.
You have other options too. You could write a bean post processor or bean definition post processor that affects the beans created by the other plugin. Depending on the particulars, that might be a better idea.
EDIT:
After seeing your comment below I created a simple example that shows how you might use a definition post processor. See the project at https://github.com/jeffbrown/postprocessordemo.
The interesting bits:
https://github.com/jeffbrown/postprocessordemo/blob/master/src/main/groovy/demo/SomeBean.groovy
package demo
class SomeBean {
String someValue
}
https://github.com/jeffbrown/postprocessordemo/blob/master/src/main/groovy/demo/SomePostProcessor.groovy
package demo
import org.springframework.beans.BeansException
import org.springframework.beans.MutablePropertyValues
import org.springframework.beans.PropertyValue
import org.springframework.beans.factory.config.BeanDefinition
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory
import org.springframework.beans.factory.support.BeanDefinitionRegistry
import org.springframework.beans.factory.support.BeanDefinitionRegistryPostProcessor
class SomePostProcessor implements BeanDefinitionRegistryPostProcessor{
#Override
void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
BeanDefinition definition = registry.getBeanDefinition('someBean')
MutablePropertyValues values = definition.getPropertyValues()
PropertyValue value = values.getPropertyValue('someValue')
def originalValue = value.getValue()
// this is where you could do your decrypting...
values.addPropertyValue('someValue', "MODIFIED: ${originalValue}".toString())
}
#Override
void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
}
}
https://github.com/jeffbrown/postprocessordemo/blob/master/grails-app/conf/spring/resources.groovy
beans = {
someBean(demo.SomeBean) {
someValue = 'Some Value'
}
somePostProcessor demo.SomePostProcessor
}
https://github.com/jeffbrown/postprocessordemo/blob/master/grails-app/init/postprocessordemo/BootStrap.groovy
package postprocessordemo
import demo.SomeBean
class BootStrap {
SomeBean someBean
def init = { servletContext ->
log.info "The Value: ${someBean.someValue}"
}
def destroy = {
}
}
At application startup you will see log output that looks something like this...
2017-10-23 19:04:54.356 INFO --- [ main] postprocessordemo.BootStrap : The Value: MODIFIED: Some Value
The "MODIFIED" there is evidence that the bean definition post processor modified the property value in the bean. In my example I am simply prepending some text to the string. In your implementation you could decrypt a password or do whatever you want to do there.
I hope that helps.
After trying Jasypt plugin and BeanPostProcessor solutions unsuccessfully for my use case, I found below solution to work perfectly.
To describe again the problem statement here,
a) we had to keep the passwords in an encrypted format inside properties files
b) and given we were packaging as a war file so the properties must not be kept inside the war to allow automated deployment scripts update the encrypted passwords depending on the environment
Jasypt plugin was a perfect solution for the use case a), but it was not able to cover the b) scenario
Moreover, the Grails LDAP Security plugin was getting loaded quite early hence Bean Post processors were also not helping out here.
Solution:
Created a new class by implementing the interface SpringApplicationRunListener. Extended its methods and parsed the properties file using YamlPropertySourceLoader
Sample code:
YamlPropertySourceLoader loader = new YamlPropertySourceLoader();
PropertySource<?> applicationYamlPropertySource = loader.load(
"application.yml", new ClassPathResource("application.yml"),"default");
return applicationYamlPropertySource;
Once the properties were loaded inside the MapPropertySource object, parsed them for the encrypted values and applied the decryption logic.
This whole implementation was executed before any plugins were initialized during Grails bootup process solving the purpose.
Hope it will help others.
When I try to register my class with autofac I get the following error: "The instance registration 'GetAllDivisionsCommand' can support SingleInstance() sharing only".
I don't understand why I'm getting this error, but assume it's something to do with the class having static member variables used for caching as that's the only thing that's different about this class. I haven't had any trouble registering any other classes as either SingleInstance or InstancePerDependency.
Essentially, the class is used to retrieve a rarely changing list of divisions from the database, and caches the result. Each time the command is run, it first checks for changes on the database and then re-runs the query if changes are detected; if not, it returns the cached list.
So I am trying to register GetAllDivisionsCommand with Autofac as an IGetAllDivisionsCommand. IGetAllDivisionsCommand itself implements IInjectableCommand, which is just a marker interface, and ICachedListCommand. The concrete command class inherits from the abstract base class CachedListCommand which is where the static member variables live.
Does anyone know what would cause this error message? SingleInstance won't work for me as I can't keep reusing the same session.
Code:
Type commandType = typeof(IInjectedCommand);
Type aCommandType = typeof(GetAllDivisions);
var commands =
from t in aCommandType.Assembly.GetExportedTypes()
where t.Namespace == aCommandType.Namespace
&& t.IsClass
&& !t.IsAbstract
&& (commandType.IsAssignableFrom(t))
let iface = t.GetInterfaces().FirstOrDefault(x => "I" + t.Name == x.Name)
select new { Command = t, Interface = iface };
foreach (var cmd in commands)
{
builder.RegisterInstance(cmd.Command).As(cmd.Interface).InstancePerLifetimeScope();
}
RegisterInstace as the name implies is for registering instances not types.
What you need is RegisterType:
foreach (var cmd in commands)
{
builder.RegisterType(cmd.Command).As(cmd.Interface).InstancePerLifetimeScope();
}
And by the way with the Autofac scanning feature your registration code is roughly equivalent:
builder
.RegisterAssemblyTypes(aCommandType.Assembly)
.AssignableTo<IInjectedCommand>()
.InNamespace(aCommandType.Namespace)
.AsImplementedInterfaces()
.InstancePerLifetimeScope();
In my case, I did want RegisterInstance because I actually have an instance in hand that I wanted to register.
I had
builder.RegisterInstance(myInstance).InstancePerDependency();
The documentation for InstancePerDependency reads:
Configure the component so that every dependent component or call to
Resolve() gets a new, unique instance (default.)
On closer inspection, it makes sense that registering an instance with "instance per dependency" is not possible, since it is not possible for Autofac to give back a new instance each time Resolve is called if there is in fact 1 instance registered.
So, in my case, the solution was this.
builder.RegisterInstance(myInstance).SingleInstance();
The Autofac exception could possibly have been worded more clearly to explain this problem.
Is there any way in Struts2 by which I can get list of namespaces in my App ?
I want this as set or list at runtime .
I am using Struts2 RestActionMapper plugin.
When there invalid namespace is specified for valid action, Struts is throwing namespace error.
But I could not redirected to standard error page when this error occurs. I tried almost all options e.g.global error mapping default namespace etc . Nothing worked. So thought it would be great if I could get list of namespaces in my app, thus i could have checked invalid namespace against my list of valid namespaces and accordingly I could have thrown generic error which would finally result in my standard error page.
I am looking for how to get list of all namespaces in my project.
So basically I want to do something like this.
validNamespaces = getNamespaces();
if(validNamespaces.contains(namespaceRetrivedFromRestPlugin))
{Sysout("This is valid namespace.")}
else
{Sysout("Invalid namespace");}
This is possible, though like Steven has pretty much stated, I'm not convinced that this is the right approach to the problem you state of redirecting to an error page. But, I'll leave that part up to you and use this space to answer the namespace question.
This code will have to be in a Struts2-created object for the injection to work.
private Configuration configuration;
#Inject
public void setConfiguration(Configuration config) {
this.configuration = config;
}
protected Set<String> getNamespaces() {
Set<String> namespaces = Collections.emptySet();
Map<String, Map<String, ActionConfig>> allActionConfigs = this.configuration.getRuntimeConfiguration().getActionConfigs();
if (allActionConfigs != null) {
namespaces = allActionConfigs.keySet();
}
return namespaces;
}
The configuration can also be obtained from a ConfigurationManager. Also, you would obviously want to store these in a variable rather than calling above method over and over. If your object is, say, an interceptor, then you could call this method from the init() method and store it in a class-level variable.
I was wondering if I can capture the result of an action after the result returns and the JSP is rendered. I want to be able to take the entire result (generated HTML) and push it into memcached so I can bring it via Nginx with-out hitting the application server. Any ideas?
PS: I know I can run the interceptor after the action executes but before the result returns and the JSP is rendered, but not after the JSP is rendered.
I haven't found a way to do this inside of struts2, your best bet it to create a servlet Filter and have it modify the OutputStream.
http://onjava.com/pub/a/onjava/2003/11/19/filters.html
Hey I know its quite late now to answer you might have already found out the answer, however for others to benefit I am posting the answer.
One thing that is very similar to what you are doing is done by sitemesh filter.
Yes, filter comes before and after the Struts2 filter itself, so you can mess with the inputs and outputs easily.
But struts does evaluate JSP/freemarker/velocity and generate the final html which is passed to the user. JSP is a bit trickey because internally a servlet is called but check out org.apache.struts2.views.freemarker.FreemarkerResult class, you can see the actual html getting generated in template.process(model, writer);. This writer is actually ServletActionContext.getResponse().getWriter();
Now to get the html all you need to do is
ServletActionContext.getResponse().getWriter().toString() //This does not work out of box. To get the toString() to work you need to use a ResponseWrapper - which is the same method to get result html in Filters. See- Programming Customized Requests and Responses.
Listing to modify resulting html in struts 2. This is not tested, but it is extracted from my code I have written earlier for custom template engine. I will probably post full description in Custom template engine for struts2
public class DecoratorInterceptor implements Interceptor {
public String intercept(ActionInvocation invocation) throws Exception {
final ActionContext context = invocation.getInvocationContext ();
HttpServletResponse responseParent = (HttpServletResponse)
context.get(ServletActionContext.HTTP_RESPONSE);
CharResponseWrapper wrapper = new CharResponseWrapper(responseParent);
ServletActionContext.setResponse(wrapper);
//Actual Action called
String result = invocation.invoke();
String htmlReturned = wrapper.toString();
//play with htmlReturned ...
String modifiedhtml = pushintoMemCache(htmlReturned );
CharArrayWriter car = new CharArrayWriter();
car.write(modifiedhtml );
PrintWriter out = responseParent.getWriter();
out.write(car.toString());
out.flush();
}
#Override
public void destroy() {
// TODO Auto-generated method stub
}
#Override
public void init() {
// TODO Auto-generated method stub
}
}
Read this article - http://struts.apache.org/2.0.6/docs/interceptors.html
SUMMARY:When you request a resource
that maps to an "action", the
framework invokes the Action object.
But, before the Action is executed,
the invocation can be intercepted by
another object. After the Action
executes, the invocation could be
intercepted again. Unsurprisingly, we
call these objects "Interceptors."
Question: How do you determine if the view has been generated? Do you set a request header or an some sort of a flag to determine if the view has been generated?
You could try throwing a MemCachedException to indicate that it is time to load into a mem cache. Your interceptor code could read
try {
return invocation.invoke();
} catch (MemCachedException mce) {
// Your code to upload to MemCache.
} finally {
// blah blah clean up.
}
Within your interceptor's intercept() method, the ActionInvocation parameter has a getResult() method which returns null before Action execution (i. e. before you call invocation.invoke() in your intercept() method) and contains an implementation of Result afterwards. That object should give you some way to access the data you need, but how this is done probably depends on the class that is actually used.
See also my somewhat related question and the answer I posted after figuring it out.