JBoss AS 7 is neat but the documentation is still quite lacking (and error messages not as useful as they could be). This post summarizes how you can create your own JavaEE-compliant login module for authenticating users of your webapp deployed on JBoss AS. A working elementary username-password module provided. Why use Java EE standard authentication? Java EE security primer A part of the Java EE specification is security for web and EE applications, which makes it possible both to specify declarative constraints in your web.xml (such as “role X is required to access resources at URLs “/protected/*”) and to control it programatically, i.e. verifying that the user has a particular role (see HttpServletRequest.isUserInRole). It works as follows: You declare in your web.xml: Login configuration – primarily whether to use browser prompt (basic) or a custom login form and a name for the login realm The custom form uses “magic” values for the post action and the fields, starting with j_, which are intercepted and processed by the server The roles used in your application (typically you’d something like “user” and perhaps “admin”) What roles are required for accessing particular URL patterns (default: none) Whether HTTPS is required for some parts of the application You tell your application server how to authenticate users for that login realm, usually by associating its name with one of the available login modules in the configuration (the modules ranging from simple file-based user list to LDAP and Kerberos support). Only rarely do you need to create your own login module, the topic of this post. If this is new for you than I strongly recommend reading The Java EE 5 Tutorial – Examples: Securing Web Applications (Form-Based Authentication with a JSP Page incl. security constraint specification, Basic Authentication with JAX-WS, Securing an Enterprise Bean, Using the isCallerInRole and getCallerPrincipal Methods). Why to bother? Declarative security is nicely decoupled from the business code It’s easy to propagate security information between a webapp and for example EJBs (where you can protect a complete bean or a particular method declaratively via xml or via annotations such as @RolesAllowed) It’s easy to switch to a different authentication mechanism such as LDAP and it’s more likely that SSO will be supported Custom login module implementation options If one of the login modules (part of a security domain) provided out of the box with JBoss, such as UsersRoles, Ldap, Database, Certificate, isn’t sufficient for you then you can adjust one of them or implement your own. You can: Extend one of the concrete modules, overriding one or some of its methods to ajdust to your needs – see f.ex. how to override the DatabaseServerLoginModule to specify your own encryption of the stored passwords. This should be your primary choice, of possible. Subclass UsernamePasswordLoginModule Implement javax.security.auth.spi.LoginModule if you need maximal flexibility and portability (this is a part of Java EE, namely JAAS, and is quite complex) JBoss EAP 5 Security Guide Ch. 12.2. Custom Modules has an excellent description of the basic modules (AbstractServerLoginModule, UsernamePasswordLoginModule) and how to proceed when subclassing them or any other standard module, including description of the key methods to implement/override. You must read it. (The guide is still perfectly applicable to JBoss AS 7 in this regard.) The custom JndiUserAndPass module example, extending UsernamePasswordLoginModule, is also worth reading – it uses module options and JNDI lookup. Example: Custom UsernamePasswordLoginModule subclass See the source code of MySimpleUsernamePasswordLoginModule that extends JBoss’ UsernamePasswordLoginModule. The abstract UsernamePasswordLoginModule (source code) works by comparing the password provided by the user for equality with the password returned from the method getUsersPassword, implemented by a subclass. You can use the method getUsername to obtain the user name of the user attempting login. Implement abstract methods getUsersPassword() Implement getUsersPassword() to lookup the user’s password wherever you have it. If you do not store passwords in plain text then read how to customize the behavior via other methods below getRoleSets() Implement getRoleSets() (from AbstractServerLoginModule) to return at least one group named “Roles” and containing 0+ roles assigned to the user, see the implementation in the source code for this post. Usually you’d lookup the roles for the user somewhere (instead of returning hardcoded “user_role” role). Optionally extend initialize(..) to get access to module options etc. Usually you will also want to extend initialize(Subject subject, CallbackHandler callbackHandler, Map sharedState, Map options) (called for each authentication attempt), To get values of properties declared via the element in the security-domain configuration – see JBoss 5 custom module example To do other initialization, such as looking up a data source via JNDI – see the DatabaseServerLoginModule Optionally override other methods to customize the behavior If you do not store passwords in plain text (a wise choice!) and your hashing method isn’t supported out of the box then you can override createPasswordHash(String username, String password, String digestOption) to hash/encrypt the user-supplied password before comparison with the stored password. Alternatively you could override validatePassword(String inputPassword, String expectedPassword) to do whatever conversion on the password before comparison or even do a different type of comparison than equality. Custom login module deployment options In JBoss AS you can Deploy your login module class in a JAR as a standalone module, independently of the webapp, under /modules/, together with a module.xml – described at JBossAS7SecurityCustomLoginModules Deploy your login module class as a part of your webapp (no module.xml required) In a JAR inside WEB-INF/lib/ Directly under WEB-INF/classes In each case you have to declare a corresponding security-domain it inside JBoss configuration (standalone/configuration/standalone.xml or domain/configuration/domain.xml): The code attribute should contain the fully qualified name of your login module class and the security-domain’s name must match the declaration in jboss-web.xml: form-auth true The code Download the webapp jboss-custom-login containing the custom login module MySimpleUsernamePasswordLoginModule, follow the deployment instructions in the README.

Here are the most important subjects for software engineering, with brief explanations: 1.Object oriented analysis & design: For better maintainability, reusability and faster development, the most well accepted approach, shortly OOAD and its SOLID principals are very important for software engineering. 2.Software quality factors: Software engineering depends on some very important quality factors. Understanding and applying them is crucial. 3.Data structures & algorithms: Basic data structures like array, list, stack, tree, map, set etc. and useful algorithms are vital for software development. Their logical structure should be known. 4. Big-O notation: Big-O notation indicates the performance of an algorithm/code section. Understanding it is very important for comparing performances. 5.UML notation: UML is the universal and complete language for software design & analysis. If there is lack of UML in a development process, it feels there is no engineering. 6.Software processes and metrics: Software enginnering is not a random process. It requires a high level of systematic and some numbers to monitor those techniques. So, processes and metrics are essential. 7.Design patterns: Design patterns are standard and most effective solutions for specific problems. If you don't want to reinvent the wheel, you should learn them. 8.Operating systems basics: Learning OS basics is very important because all applications runs on it. By learning it, we can have better vision, viewpoints and performance for our applications. 9.Computer organization basics: All applications including OS requires a hardware for physical interaction. So, learning computer organization basics is vital again for better vision, viewpoints and performance. 10.Network basics: Network is related with computer organization, OS and the whole information transfer process. In any case we will face it while software development. So, it is important to learn network basics. 11.Requirement analysis: Requirement analysis is the starting point and one of the most important parts of software engineering. Performing it correctly and practically needs experience but it is very essential. 12.Software testing: Testing is another important part of software engineering. Unit testing, its best practices and techniques like black box, white box, mocking, TDD, integration testing etc. are subjects which must be known. 13.Dependency management: Library (JAR, DLL etc.) management, and widely known tools (Maven, Ant, Ivy etc.) are essential for large projects. Otherwise, antipatterns like Jar Hell are inevitable. 14.Continuous integration: Continuous integration brings easiness and automaticity for testing large modules, components and also performs auto-versioning. Its aim and tools (like Hudson etc.) should be known. 15.ORM (Object relational mapping): ORM and its widely known implementation Hibernate framework is an important technique for mapping objects into database tables. It reduces code length and maintenance time. 16.DI (Dependency Injection): DI or IoC (Inversion of Control) and its widely known implementation Spring framework makes life easy for object creation and lifetime management on big enterprise applications. 17.Version controlling systems: VCS tools (SVN, TFS, CVS etc.) are very important by saving so much time for collaborative works and versioning. Their logical viewpoint and standard cammands should be known. 18.Internationalization (i18n): i18n by extracting strings into external files is the best way of supporting multiple languages in our applications. Its practices on different IDEs and technologies must be known. 19.Architectural patterns: Understanding architectural design patterns (like MVC, MVP, MVVM etc.) is essential for producing a maintainable, clean, extendable and testable source code. 20.Writing clean code: Working code is not enough, it must be readable and maintainable also. So, code formatting and readable code development techniques are needed to be known and applied.

in this article we'll show you how you can use the w3c geolocation api to measure the speed and the heading of your car while driving. this article further uses svg to render the speed gauge and heading compass. what we'll create in this article is the following: here you can see two gauges. one will show the heading you're driving to, and the other shows the speed in kilometers. you can test this out yourself by using the following link: open this in gps enable device . once opened the browser will probably ask you to allow access to your location. if you enable this and start moving, you'll see the two gauges move appropriately. getting all this to work is actually very easy and consists of the following steps: alter the svg images so we can rotate the needle and add to page. use the geolocation api to determine the current speed and heading update the needle based on the current and previous value we'll start with the svg part. alter the svg images so we can rotate the needle and add to page for the images i decided to use svg. svg has the advantage that it can scale without losing detail, and you can easily manipulate and animate the various parts of a svg image. both the svg images were copied from openclipart.org : compass rose speedometer these are vector graphics, both created using illustrator. before we can rotate the needles in these images we need to make a couple of small changes to the svg code. with svg you can apply matrix transformations to each svg element, with this you can easily rotate, skew, scale or translate a component. besides the matrix transformation you can also apply the rotation and translation directly using the translate and rotate keywords. in this example i've used the translaten and rotate functions directly. when working with these functions you have to take into account that the rotate function doesn't rotate around the center of the component, it rotates around point 0,0. so we need to make sure that for our needles the point we want to rotate around is set at 0,0. without diving into too much details, i removed the two needles from the image, and added them as a seperate group to the svg image. i then made sure the needles we're drawn relative to the 0,0 point i wanted to rotate around. for the speedometer the needle is now defined as this: and for the compass the needle is defined like this: if you know how to read svg, you can see that these figures are now drawn around their rotation point (the bottom center for the speedomoter and the center for the compass). as you can see we also added a specific id for both these elements. this way we can reference them directly from our javascript later on and update the transform property from a jquery animation. next we just need to add these to the page. for this i used d3.js , which has all kinds of helper functions for svg and which you can use to load these elements like this: function loadgraphics() { d3.xml("assets/compass.svg", "image/svg+xml", function(xml) { document.body.appendchild(xml.documentelement); }); d3.xml("assets/speed.svg", "image/svg+xml", function(xml) { document.body.appendchild(xml.documentelement); }); } and with this we've got our visualization components ready. use the geolocation api to determine the current speed and heading the next step is using the geolocation api to access the speed and heading properties. you can get this information from the position object that is provided to you by this api: interface position { readonly attribute coordinates coords; readonly attribute domtimestamp timestamp; }; this object has a coordinate object that contains the information we're looking for: interface coordinates { readonly attribute double latitude; readonly attribute double longitude; readonly attribute double? altitude; readonly attribute double accuracy; readonly attribute double? altitudeaccuracy; readonly attribute double? heading; readonly attribute double? speed; }; a lot of useful attributes, but we're only interested in these last two. the heading (from 0 to 360) shows the direction we're moving in, and the speed in meters per second is, as you've probably guessed, the speed we're moving at. there are two different options to get these values. we can poll ourselves for these values (e.g. setinterval) or we can wait wacth our position. in this second case you automatically recieve an update. in this example we use the second approach: function initgeo() { navigator.geolocation.watchposition( geosuccess, geofailure, { enablehighaccuracy:true, maximumage:30000, timeout:20000 } ); //movespeed(30); //movecompassneedle(56); } var count = 0; function geosuccess(event) { $("#debugoutput").text("geosuccess: " + count++ + " : " + event.coords.heading + ":" + event.coords.speed); var heading = event.coords.heading; var speed = event.coords.speed; if (heading != null && speed !=null && speed > 0) { movecompassneedle(heading); } if (speed != null) { // update the speed movespeed(speed); } } with this piece of code, we register a callback function on the watchposition. we also add a couple of properties to the watchposition function. with these properties we tell the api to use gps (enablehighaccuracy) and set some timeout and caching values. whenever we receive an update from the api the geosuccess function is called. this function recieves a position object (shown earlier) that we use to access the speed and the heading. based on the value of the heading and the speed we update the compass and the speedomoter. update the needle based on the current and previous value to update the needles we use jquery animations for the easing. normally you use a jquery animation to animatie css properties of an object, but you can also use this to animate arbitrary properties. to animate the speedomoter we use the following: var currentspeed = {property: 0}; function movespeed(speed) { // we use a svg transform to move to correct orientation and location var translatevalue = "translate(171,157)"; // to is in the range of 45 to 315, which is 0 to 260 km var to = {property: math.round((speed*3.6/250) *270) + 45}; // stop the current animation and run to the new one $(currentspeed).stop().animate(to, { duration: 2000, step: function() { $("#speed").attr("transform", translatevalue + " rotate(" + this.property + ")") } }); } we create a custom object, currentspeed, with a single property. this property is set to the rotate ratio that reflects the current speed. next, this property is used in a jquery animation. note that we stop any existing animations, should we get an update when the current animation is still running. in the step property of the animation we set the transfrom value of the svg element. this will rotate the needle, in two seconds, from the old value to the new value. and to animate the compass we do pretty much the same thing: var currentcompassposition = {property: 0}; function movecompassneedle(heading) { // we use a svg transform to move to correct orientation and location var translatevalue = "translate(225,231)"; var to = {property: heading}; // stop the current animation and run to the new one $(currentcompassposition).stop().animate(to, { duration: 2000, step: function() { $("#compass").attr("transform", translatevalue + " rotate(" + this.property + ")") } }); } there is a smal bug i ran into with this setup. sometimes my phone lost its gps signal (running firefox mobile), and that stopped the dials moving. refreshing the webpage was enough to get things started again however. i might change this to actively pull the information using the getcurrentlocation api call, to see whether that works better. another issue is that there is no way, at least that i found, for you to disable the phone entering sleep mode from the browser. so unless you configure your phone to not go to sleep, the screen will go black.

I've seen a lot of discussion about how to monitor Camel based applications. Most people are looking for the following features: ability to view services (contexts, endpoints, routes), to view performance statistics (route throughput, etc) and to perform basic operations (start/stop routes, send messages, etc). This post will breakdown the options (that I know of) that are available today (as of Camel 2.8). If you have used other approaches or know of other ongoing development in this area, please let me know. JMX APIs Camel uses JMX to provide a standardized way to access metadata about contexts/routes/endpoints defined in a given application. Also, you can use JMX to interact with these components (start/stop routes, etc) in some interesting ways. I recently had some very specific Camel/ActiveMQ monitoring requests from a client. After looking at the options, we ended up building a standalone Tomcat web app that used JSPs, jQuery, Ajax and JMX APIs to view route/endpoint statistics, manage Camel routes (stop, start, etc) and monitor/manipulate ActiveMQ queues. It provided some much needed visibility and management features for our Camel/ActiveMQ based message processing application... CamelContext If you have a handle to the CamelContext, there are various APIs that can help describe and manage routes and endpoints. These are used by the existing Camel Web Console and can be used to build custom interface to retrieve and use this information in various ways... here are some of the notable APIs... getRouteDefinitions() getEndpoints() getEndpointsMap() getRouteStatus(routeId) startRoute(routeId) stopRoute(routeId) removeRoute(routeId) addRoutes(routeBuilder) suspendRoute(routeId) resumeRoute(routeId) With a little creativity, you can use these APIs to manage/monitor and re-wire a Camel application dynamically. Camel Web Console This console provides web and REST interfaces to Camel contexts/routes/endpoints and allows you to view/manage endpoints/routes, send messages to endpoints, viewing route statistics, etc. That being said, using this web console with an existing Camel application is tricky at the moment. It's currently deployed as a war file that only has access to the CamelContext defined in its embedded spring XML file. Though the entire camel-web project can be embedded and customized in your application if you desire (and know Scalate). Given my recent client requirements, I opted to build my own basic app using JSPs/JMX as described above. There has been some recent support for deploying this console in OSGI, where it should be able to view any CamelContexts deployed in the container, etc. However, I'm yet to see this work...more on this later. Using Camel APIs There are also a number of Camel technologies/patterns that can be used to add monitoring to existing routes. wire tap - can add message logging (to a file or JMS queue/topic, etc) or other inline processing advicewith - can be used to modify existing routes to apply before/after operations or add/remove operations in a route intercept - can be used to intercept Exchanges while they are in route, can apply to all endpoints, certain endpoints or just starting endpoints BrowsableEndpoint - is an interface which Endpoints may implement to support the browsing of the exchanges which are pending or have been sent on it. That being said, it takes some creativity to use these effectively and caution to not adversely affect the routes you are trying to monitor. Hyperic HQ You can use this tool to monitor Servicemix (or any process), but it more geared towards system monitoring and JVM stats. I didn't find it useful for any Camel specific monitoring. jConsole/VisualVM these are standard JMX based consoles. They aren't web based and can't be customized (easily anyways) to provide anything more than a tree-like view of JMX MBeans. If you know where to look though, you can do a lot with it. Summary These are just some quick notes at this point. As I learn about other ways of monitoring Camel, I'll update this list and give some more detailed comparison. Any comments are welcome...

Some web applications may need a "Remember Me" functionality. This means that, after a user login, user will have access from same machine to all its data even after session expired. This access will be possible until user does a logout. If you are using Spring and its login form, then you should use "Remember Me" functionality already implemented inside the framework. Some web frameworks also offer a type of SignIn panel which already has "remember me" built-in. But in case you have to implement "Remember Me" functionality by your own, this can be easily achieved using Cookies. Java has a Cookie class named javax.servlet.http.Cookie. Algorithm is straight-forward: your login panel must contain a "Remember Me" check after a succesfull login with "Remember Me" check selected, you can create two cookies: one to keep the value for rememberMe and one to keep a token which has to identify the logged user. For sake of security, this token must never contain user name or user password. The ideea is to generate a random id as token value. And token value aside with user id must be saved in your storage (database) whenever a login is needed, you have to look if there is any cookie saved by you, and if so and your "rememberMe" value is true, you can take the user from storage based on your token and do an automatic login. when a logout is done, you have to delete the cookie that keeps the token To add a cookie, you have to specify the maximum age of the cookie in seconds : HttpServletResponse servletResponse = ...; Cookie c = new Cookie(COOKIE_NAME, encodeString(uuid)); c.setMaxAge(365 * 24 * 60 * 60); // one year servletResponse.addCookie(c); To delete a cookie, you have to find cookie by name and set its maximum age to 0, before adding it to servlet response: HttpServletRequest servletRequest = ...; HttpServletResponse servletResponse = ... ; Cookie[] cookies = servletRequest.getCookies(); for (int i = 0; i < cookies.length; i++) { Cookie c = cookies[i]; if (c.getName().equals(COOKIE_NAME)) { c.setMaxAge(0); c.setValue(null); servletResponse.addCookie(c); } }

I decided to share some tips about this EE environment javaMail api configuration.

Manipulating JAXWS header on the client Side like adding WSS username token or logging saop message.

Introduction: Building modern HTTP/RESTful/RPC services has become very easy with the new ASP.NET Web API framework. Using ASP.NET Web API framework, you can create HTTP services which can be accessed from browsers, machines, mobile devices and other clients. Developing HTTP services is now quite easy for ASP.NET MVC developer becasue ASP.NET Web API is now included in ASP.NET MVC. In addition to developing HTTP services, it is also important to return meaningful response to client if a resource(uri) not found(HTTP 404) for a reason(for example, mistyped resource uri). It is also important to make this response centralized so you can configure all of 'HTTP 404 Not Found' resource at one place. In this article, I will show you how to handle 'HTTP 404 Not Found' at one place. Description: Let's say that you are developing a HTTP RESTful application using ASP.NET Web API framework. In this application you need to handle HTTP 404 errors in a centralized location. From ASP.NET Web API point of you, you need to handle these situations, No route matched. Route is matched but no {controller} has been found on route. No type with {controller} name has been found. No matching action method found in the selected controller due to no action method start with the request HTTP method verb or no action method with IActionHttpMethodProviderRoute implemented attribute found or no method with {action} name found or no method with the matching {action} name found. Now, let create a ErrorController with Handle404 action method. This action method will be used in all of the above cases for sending HTTP 404 response message to the client. public class ErrorController : ApiController { [HttpGet, HttpPost, HttpPut, HttpDelete, HttpHead, HttpOptions, AcceptVerbs("PATCH")] public HttpResponseMessage Handle404() { var responseMessage = new HttpResponseMessage(HttpStatusCode.NotFound); responseMessage.ReasonPhrase = "The requested resource is not found"; return responseMessage; } } You can easily change the above action method to send some other specific HTTP 404 error response. If a client of your HTTP service send a request to a resource(uri) and no route matched with this uri on server then you can route the request to the above Handle404 method using a custom route. Put this route at the very bottom of route configuration, routes.MapHttpRoute( name: "Error404", routeTemplate: "{*url}", defaults: new { controller = "Error", action = "Handle404" } ); Now you need handle the case when there is no {controller} in the matching route or when there is no type with {controller} name found. You can easily handle this case and route the request to the above Handle404 method using a custom IHttpControllerSelector. Here is the definition of a custom IHttpControllerSelector, public class HttpNotFoundAwareDefaultHttpControllerSelector : DefaultHttpControllerSelector { public HttpNotFoundAwareDefaultHttpControllerSelector(HttpConfiguration configuration) : base(configuration) { } public override HttpControllerDescriptor SelectController(HttpRequestMessage request) { HttpControllerDescriptor decriptor = null; try { decriptor = base.SelectController(request); } catch (HttpResponseException ex) { var code = ex.Response.StatusCode; if (code != HttpStatusCode.NotFound) throw; var routeValues = request.GetRouteData().Values; routeValues["controller"] = "Error"; routeValues["action"] = "Handle404"; decriptor = base.SelectController(request); } return decriptor; } } Next, it is also required to pass the request to the above Handle404 method if no matching action method found in the selected controller due to the reason discussed above. This situation can also be easily handled through a custom IHttpActionSelector. Here is the source of custom IHttpActionSelector, public class HttpNotFoundAwareControllerActionSelector : ApiControllerActionSelector { public HttpNotFoundAwareControllerActionSelector() { } public override HttpActionDescriptor SelectAction(HttpControllerContext controllerContext) { HttpActionDescriptor decriptor = null; try { decriptor = base.SelectAction(controllerContext); } catch (HttpResponseException ex) { var code = ex.Response.StatusCode; if (code != HttpStatusCode.NotFound && code != HttpStatusCode.MethodNotAllowed) throw; var routeData = controllerContext.RouteData; routeData.Values["action"] = "Handle404"; IHttpController httpController = new ErrorController(); controllerContext.Controller = httpController; controllerContext.ControllerDescriptor = new HttpControllerDescriptor(controllerContext.Configuration, "Error", httpController.GetType()); decriptor = base.SelectAction(controllerContext); } return decriptor; } } Finally, we need to register the custom IHttpControllerSelector and IHttpActionSelector. Open global.asax.cs file and add these lines, configuration.Services.Replace(typeof(IHttpControllerSelector), new HttpNotFoundAwareDefaultHttpControllerSelector(configuration)); configuration.Services.Replace(typeof(IHttpActionSelector), new HttpNotFoundAwareControllerActionSelector()); Summary: In addition to building an application for HTTP services, it is also important to send meaningful centralized information in response when something goes wrong, for example 'HTTP 404 Not Found' error. In this article, I showed you how to handle 'HTTP 404 Not Found' error in a centralized location. Hopefully you will enjoy this article too.

Here is a quick example of how to programmatically access ActiveMQ MBeans to monitor and manipulate message queues... First, get a connection to a JMX server (assumes localhost, port 1099, no auth) Note, always cache the connection for subsequent requests (can cause memory utilization issues otherwise) JMXServiceURL url = new JMXServiceURL("service:jmx:rmi:///jndi/rmi://localhost:1099/jmxrmi"); JMXConnector jmxc = JMXConnectorFactory.connect(url); MBeanServerConnection conn = jmxc.getMBeanServerConnection(); Then, you can execute various operations such as addQueue, removeQueue, etc... String operationName="addQueue"; String parameter="MyNewQueue"; ObjectName activeMQ = new ObjectName("org.apache.activemq:BrokerName=localhost,Type=Broker"); if(parameter != null) { Object[] params = {parameter}; String[] sig = {"java.lang.String"}; conn.invoke(activeMQ, operationName, params, sig); } else { conn.invoke(activeMQ, operationName,null,null); } Also, you can get an ActiveMQ QueueViewMBean instance for a specified queue name... ObjectName activeMQ = new ObjectName("org.apache.activemq:BrokerName=localhost,Type=Broker"); BrokerViewMBean mbean = (BrokerViewMBean) MBeanServerInvocationHandler.newProxyInstance(conn, activeMQ,BrokerViewMBean.class, true); for (ObjectName name : mbean.getQueues()) { QueueViewMBean queueMbean = (QueueViewMBean) MBeanServerInvocationHandler.newProxyInstance(mbsc, name, QueueViewMBean.class, true); if (queueMbean.getName().equals(queueName)) { queueViewBeanCache.put(cacheKey, queueMbean); return queueMbean; } } Then, execute one of several APIs against the QueueViewMBean instance... Queue monitoring - getEnqueueCount(), getDequeueCount(), getConsumerCount(), etc... Queue manipulation - purge(), getMessage(String messageId), removeMessage(String messageId), moveMessageTo(String messageId, String destinationName), copyMessageTo(String messageId, String destinationName), etc... Summary The APIs can easily be used to build a web or command line based tool to support remote ActiveMQ management features. That being said, all of these features are available via the JMX console itself and ActiveMQ does provide a web console to support some management/monitoring tasks. See these pages for more information... http://activemq.apache.org/jmx-support.html http://activemq.apache.org/web-console.html

Microsoft offered programmers several different ways of dealing with the asynchronous programming since .NET 1.0. The first model was Asynchronous programming model or APM for short. The pattern is implemented with two methods named BeginOperation and EndOperation. .NET 4 introduced new pattern – Task Asynchronous Pattern and with the introduction of .NET 4.5, Microsoft added language support for language integrated asynchronous coding style. You can check the MSDN for more samples and information. I will assume that you are familiar with it and have written code using it. You can wrap existing APM pattern into TPL pattern using the Task.Factory.FromAsync methods. For example: public static Task> ExecuteAsync(this DataServiceQuery query, object state) { return Task.Factory.FromAsync>(query.BeginExecute, query.EndExecute, state); } It is easy to wrap most of the asynchronous functions this way, but some cannot be since the wrapper functions assume that the last two parameters to the BeginOperation are AsyncCallback and object, and there are some versions of asynchronous operations that have different specifications. Examples: 1. Extra parameters after the object state parameter: IAsyncResult DataServiceContext.BeginExecuteBatch( AsyncCallback callback, object state, params DataServiceRequest[] queries); 2. Missing the expected object state parameter and different return type: ICancelableAsyncResult BeginQuery(AsyncCallback callBack); WorkItemCollection EndQuery(ICancelableAsyncResult car); Short solution for the first example The short and elegant way for wrapping the first example is to provide the following wrapper: public static Task ExecuteBatchAsync(this DataServiceContext context, object state, params DataServiceRequest[] queries) { if (context == null) throw new ArgumentNullException("context"); return Task.Factory.FromAsync( context.BeginExecuteBatch(null, state, queries), context.EndExecuteBatch); } We simply call the Begin method ourselves and then wrap it using an another overload for FromAsync function. The longer way However, we can fully wrap it ourselves by simulating what the FromAsync wrapper does. The complete code is listed below. public static Task ExecuteBatchAsync(this DataServiceContext context, object state, params DataServiceRequest[] queries) { // this will be our sentry that will know when our async operation is completed var tcs = new TaskCompletionSource(); try { context.BeginExecuteBatch((iar) => { try { var result = context.EndExecuteBatch(iar as ICancelableAsyncResult); tcs.TrySetResult(result); } catch (OperationCanceledException ex) { // if the inner operation was canceled, this task is cancelled too tcs.TrySetCanceled(); } catch (Exception ex) { // general exception has been set bool flag = tcs.TrySetException(ex); if (flag && ex as ThreadAbortException != null) { tcs.Task.m_contingentProperties.m_exceptionsHolder.MarkAsHandled(false); } } }, state, queries); } catch { tcs.TrySetResult(default(DataServiceResponse)); // propagate exceptions to the outside throw; } return tcs.Task; } Besides educational benefits, writing the full wrapper code allows us to add cancellation, logging and diagnostic information. Once we understand how to wrap APM pattern, We can now tackle the second problem easily. Handling the BeginQuery/EndQuery We will first create our own wrapper function in the spirit of the above code with the notable difference that we use the ICancelableAsyncResult interface instead of the IAsyncResult. public static class TaskEx { public static Task FromAsync(Func beginMethod, Func endMethod) { if (beginMethod == null) throw new ArgumentNullException("beginMethod"); if (endMethod == null) throw new ArgumentNullException("endMethod"); var tcs = new TaskCompletionSource(); try { beginMethod((iar) => { try { var result = endMethod(iar as ICancelableAsyncResult); tcs.TrySetResult(result); } catch (OperationCanceledException ex) { tcs.TrySetCanceled(); } catch (Exception ex) { bool flag = tcs.TrySetException(ex); if (flag && ex as ThreadAbortException != null) { tcs.Task.m_contingentProperties.m_exceptionsHolder.MarkAsHandled(false); } } }); } catch { tcs.TrySetResult(default(TResult)); throw; } return tcs.Task; } } The code is pretty self-explanatory and we can go ahead with the wrapping. There are four different operations that are exposed both in synchronous and asynchronous version: Query, LinkQuery, CountOnlyQuery and RegularQuery. The extension methods are short since we have already created our generic wrapper above: public static Task RunQueryAsync(this Query query) { return TaskEx.FromAsync(query.BeginQuery, query.EndQuery); } public static Task RunLinkQueryAsync(this Query query) { return TaskEx.FromAsync(query.BeginLinkQuery, query.EndLinkQuery); } public static Task RunCountOnlyQueryAsync(this Query query) { return TaskEx.FromAsync(query.BeginCountOnlyQuery, query.EndCountOnlyQuery); } public static Task RunRegularQueryAsync(this Query query) { return TaskEx.FromAsync(query.BeginRegularQuery, query.EndRegularQuery); } That is it for today, you can write your own handy extensions easily for APM functions out there.

Performance problems are one of the biggest challenges to expect when designing and implementing Java EE related technologies.

Apache Camel has a very powerful bean injection framework which allows developers to focus only on solving business problems. However there are situations when you need to do a little bit more. Read below to see how easy it is to setup aspects (AspectJ) in Apache Camel. Use case In Qualitas I have an installation route which consists of 10 mandatory and 2 optional processors. Some processors like property resolvers or validators don't modify contents of message's body so I have to always copy body from the in message to out message. Also, all my processors require some headers to function properly. Finally, I would like to get a status updated after each of my processors either finishes processing successfully or fails. Setting up AspectJ This is just a plain Spring configuration frankly. All you have to do is: Apache Camel processor aspect To define aspect in AspectJ I used AspectJ-specific @Aspect and @Around annotations: @Aspect @Component @Order(Ordered.LOWEST) public class HeadersAndBodyCopierAspect { @Around("execution(* com.googlecode.qualitas.internal.installation..*.process(org.apache.camel.Exchange)) && args(exchange) && target(org.apache.camel.Processor)") public Object copyHeadersAndBody(ProceedingJoinPoint pjp, Exchange exchange) throws Throwable { Object retValue = pjp.proceed(); Message in = exchange.getIn(); Message out = exchange.getOut(); // always copy headers out.setHeaders(in.getHeaders()); // if output body is empty copy it from input if (out.getBody() == null) { out.setBody(in.getBody()); } return retValue; } } I also used @Order Spring-specific annotation to control the order of execution of my aspects and @Component for automatic context scanning. Now, the join point is defined as execution(* com.googlecode.qualitas.internal.installation..*.process(org.apache.camel.Exchange)) && args(exchange) && target(org.apache.camel.Processor) which basically means: apply this aspect to all process methods which are defined in all classes in com.googlecode.qualitas.internal.installation or subpackages and which take Exchange object as an argument there can be many custom methods whose names may be process and whose argument may be Exchange, so I added one more constraint, this class has to be an instance of Processor args(exchange) allows me to add Exchange object as an argument to my aspect More complex aspects and source code Of course in Spring you can inject other beans directly into your aspects. I used it in my ProcessStatusUpdaterAspect aspect which you can find in Qualitas repo on GoogleCode or GitHub. If you are interested in trying out the whole Qualitas system take a look at the following two links: BuildingTheProject and RunningTheProject. cheers, Łukasz

The model contains the business logic and interact with the persistance storage to store, retrive and manipulate data. The view is responsible for dispalying the results back to the user. In Struts the view layer is implemented using JSP. The controller handles all the request from the user and selects the appropriate view to return. In Sruts the controller's job is done by the ActionServlet. The following events happen when the Client browser issues an HTTP request. The ActionServlet receives the request. The struts-config.xml file contains the details regarding the Actions, ActionForms, ActionMappings and ActionForwards. During the startup the ActionServelet reads the struts-config.xml file and creates a database of configuration objects. Later while processing the request the ActionServlet makes decision by refering to this object. When the ActionServlet receives the request it does the following tasks. Bundles all the request values into a JavaBean class which extends Struts ActionForm class. Decides which action class to invoke to process the request. Validate the data entered by the user. The action class process the request with the help of the model component. The model interacts with the database and process the request. After completing the request processing the Action class returns an ActionForward to the controller. Based on the ActionForward the controller will invoke the appropriate view. The HTTP response is rendered back to the user by the view component.

This is interesting stuff; Jonas Bonér organized some general some latency data by Peter Norvig as a Gist, and others expanded on it. What's interesting is how, scaling time up by a billion, converts a CPU instruction cycle into approximately one heartbeat, and yields a disk seek time of "a semester in university". ### Latency numbers every programmer should know L1 cache reference ......................... 0.5 ns Branch mispredict ............................ 5 ns L2 cache reference ........................... 7 ns Mutex lock/unlock ........................... 25 ns Main memory reference ...................... 100 ns Compress 1K bytes with Zippy ............. 3,000 ns = 3 µs Send 2K bytes over 1 Gbps network ....... 20,000 ns = 20 µs SSD random read ........................ 150,000 ns = 150 µs Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs Round trip within same datacenter ...... 500,000 ns = 0.5 ms Read 1 MB sequentially from SSD* ..... 1,000,000 ns = 1 ms Disk seek ........................... 10,000,000 ns = 10 ms Read 1 MB sequentially from disk .... 20,000,000 ns = 20 ms Send packet CA->Netherlands->CA .... 150,000,000 ns = 150 ms Assuming ~1GB/sec SSD  Visual chart provided by [ayshen](https://gist.github.com/ayshen) Data by [Jeff Dean](http://research.google.com/people/jeff/) Originally by [Peter Norvig](http://norvig.com/21-days.html#answers) Lets multiply all these durations by a billion: Magnitudes: ### Minute: L1 cache reference 0.5 s One heart beat (0.5 s) Branch mispredict 5 s Yawn L2 cache reference 7 s Long yawn Mutex lock/unlock 25 s Making a coffee ### Hour: Main memory reference 100 s Brushing your teeth Compress 1K bytes with Zippy 50 min One episode of a TV show (including ad breaks) ### Day: Send 2K bytes over 1 Gbps network 5.5 hr From lunch to end of work day ### Week SSD random read 1.7 days A normal weekend Read 1 MB sequentially from memory 2.9 days A long weekend Round trip within same datacenter 5.8 days A medium vacation Read 1 MB sequentially from SSD 11.6 days Waiting for almost 2 weeks for a delivery ### Year Disk seek 16.5 weeks A semester in university Read 1 MB sequentially from disk 7.8 months Almost producing a new human being The above 2 together 1 year ### Decade Send packet CA->Netherlands->CA 4.8 years Average time it takes to complete a bachelor's degree

One of the advantages of code generation is the ability to see how a specific language feature or framework is used. As I discussed in the post NetBeans 7.2 beta: Faster and More Helpful, NetBeans 7.2 beta provides TestNG integration. I did not elaborate further in that post other than a single reference to that feature because I wanted to devote this post to the subject. I use this post to demonstrate how NetBeans 7.2 can be used to help a developer new to TestNG start using this alternative (to JUnit) test framework. NetBeans 7.2's New File wizard makes it easier to create an empty TestNG test case. This is demonstrated in the following screen snapshots that are kicked off by using New File | Unit Tests (note that "New File" is available under the "File" drop-down menu or by right-clicking in the Projects window). Running the TestNG test case creation as shown above leads to the following generated test code. TestNGDemo.java (Generated by NetBeans 7.2) package dustin.examples; import org.testng.annotations.AfterMethod; import org.testng.annotations.AfterClass; import org.testng.annotations.BeforeMethod; import org.testng.annotations.BeforeClass; import org.testng.annotations.Test; import org.testng.Assert; /** * * @author Dustin */ public class TestNGDemo { public TestNGDemo() { } @BeforeClass public void setUpClass() { } @AfterClass public void tearDownClass() { } @BeforeMethod public void setUp() { } @AfterMethod public void tearDown() { } // TODO add test methods here. // The methods must be annotated with annotation @Test. For example: // // @Test // public void hello() {} } The test generated by NetBeans 7.2 includes comments indicate how test methods are added and annotated (similar to modern versions of JUnit). The generated code also shows some annotations for overall test case set up and tear down and for per-test set up and tear down (annotations are similar to JUnit's). NetBeans identifies import statements that are not yet used at this point (import org.testng.annotations.Test; and import org.testng.Assert;), but are likely to be used and so have been included in the generated code. I can add a test method easily to this generated test case. The following code snippet is a test method using TestNG. testIntegerArithmeticMultiplyIntegers() @Test public void testIntegerArithmeticMultiplyIntegers() { final IntegerArithmetic instance = new IntegerArithmetic(); final int[] integers = {4, 5, 6}; final int expectedProduct = 2 * 3 * 4 * 5 * 6; final int product = instance.multiplyIntegers(2, 3, integers); assertEquals(product, expectedProduct); } This, of course, looks very similar to the JUnit equivalent I used against the same IntegerArithmetic class that I used for testing illustrations in the posts Improving On assertEquals with JUnit and Hamcrest and JUnit's Built-in Hamcrest Core Matcher Support. The following screen snapshot shows the output in NetBeans 7.2 beta from right-clicking on the test case class and selecting "Run File" (Shift+F6). The text output of the TestNG run provided in the NetBeans 7.2 beta is reproduced next. [TestNG] Running: Command line suite [VerboseTestNG] RUNNING: Suite: "Command line test" containing "1" Tests (config: null) [VerboseTestNG] INVOKING CONFIGURATION: "Command line test" - @BeforeClass dustin.examples.TestNGDemo.setUpClass() [VerboseTestNG] PASSED CONFIGURATION: "Command line test" - @BeforeClass dustin.examples.TestNGDemo.setUpClass() finished in 33 ms [VerboseTestNG] INVOKING CONFIGURATION: "Command line test" - @BeforeMethod dustin.examples.TestNGDemo.setUp() [VerboseTestNG] PASSED CONFIGURATION: "Command line test" - @BeforeMethod dustin.examples.TestNGDemo.setUp() finished in 2 ms [VerboseTestNG] INVOKING: "Command line test" - dustin.examples.TestNGDemo.testIntegerArithmeticMultiplyIntegers() [VerboseTestNG] PASSED: "Command line test" - dustin.examples.TestNGDemo.testIntegerArithmeticMultiplyIntegers() finished in 12 ms [VerboseTestNG] INVOKING CONFIGURATION: "Command line test" - @AfterMethod dustin.examples.TestNGDemo.tearDown() [VerboseTestNG] PASSED CONFIGURATION: "Command line test" - @AfterMethod dustin.examples.TestNGDemo.tearDown() finished in 1 ms [VerboseTestNG] INVOKING CONFIGURATION: "Command line test" - @AfterClass dustin.examples.TestNGDemo.tearDownClass() [VerboseTestNG] PASSED CONFIGURATION: "Command line test" - @AfterClass dustin.examples.TestNGDemo.tearDownClass() finished in 1 ms [VerboseTestNG] [VerboseTestNG] =============================================== [VerboseTestNG] Command line test [VerboseTestNG] Tests run: 1, Failures: 0, Skips: 0 [VerboseTestNG] =============================================== =============================================== Command line suite Total tests run: 1, Failures: 0, Skips: 0 =============================================== Deleting directory C:\Users\Dustin\AppData\Local\Temp\dustin.examples.TestNGDemo test: BUILD SUCCESSFUL (total time: 2 seconds) The above example shows how easy it is to start using TestNG, especially if one is moving to TestNG from JUnit and is using NetBeans 7.2 beta. Of course, there is much more to TestNG than this, but learning a new framework is typically most difficult at the very beginning and NetBeans 7.2 gets one off to a fast start.

infographic: clouds computing and history i have prepared three new infographics for you;aall of them related with cloud computing. these infographics will tell you about history of cloud computing, its definition, and who needs this cloud. i think that this will be interesting for you. information graphics (known as infographics) are one of the best ways to transfer some information into a reader’s mind. it can be something new, or other useful information gathered in one place. nowadays many people don’t have enough time to read a lot of text on multiple screens. infographics makes the information intuitive and understandable. that’s why we would like to share the best relevant infographics from all over the web. original source: cloud computing by the small business authority original source: a complete history of cloud computing original source: hosting decisions, from the chalkboard

A Robust Splitter Aggregator Design Strategy - Messaging Gateway Adapter Pattern What do we mean by robust? In the context of this article, robustness refers to an ability to manage exception conditions within a flow without immediately returning to the caller. In some processing scenarios n of m responses is good enough to proceed to conclusion. Example processing scenarios that typically have these tendencies are: Quotations for finance, insurance and booking systems. Fan-out publishing systems. Why do we need Robust Splitter Aggregator Designs? First and foremost an introduction to a typical Splitter Aggregator pattern maybe necessary. The Splitter is an EIP pattern that describes a mechanism for breaking composite messages into parts in order that they can be processed individually. A Router is an EIP pattern that describes routing messages into channels - aiming them at specific messaging endpoints. The Aggregator is an EIP pattern that collates and stores a set of messages that belong to a group, and releases them when that group is complete. Together, those three EIP constructs form a powerful mechanism for dividing processing into distinct units of work. Spring Integration (SI) uses the same pattern terminology as EIP and so readers of that methodology will be quite comfortable with Spring Integration Framework constructs. The SI Framework allows significant customisations of all three of those constructs and furthermore, by simply using asynchronous channels as you would in any other multi-threaded configuration, allows those units of work to be executed in parallel. An interesting challenge working with SI Splitter Aggregator designs is building appropriately robust flows that operate predictably in a number of invocation scenarios. A simple splitter aggregator design can be used in many circumstances and operate without heavy customisation of the SI constructs. However, some service requirements demand a more robust processing strategy and therefore more complex configuration. The following sections describe and show what a Simple Splitter Aggregator design actually looks like, the type of processing your design must be able to deal with and then goes on to suggest candidate solutions for more robust processing. A Simple Splitter Aggregator Design The following Splitter Aggregator design shows a simple flow that receives document request messages into messaging gateway, splits the message into two processing routes and then aggregates the response. Note that the diagram has been built from EIP constructs in OmniGraffle rather than being an Integration Graph view from within STS; the channels are missing from the diagram for the sake of brevity. SI Constructs in detail: Messaging Gateways - there are three messaging gateways. A number of configurations are available for gateway specifications but significantly can return business objects, exceptions and nulls (following a timeout). The gateway to the far left is the service gateway for which we are defining the flow. The other two gateways, between the Router and Aggregator, are external systems that will be providing responses to business questions that our flow generates. The Splitter - a single splitter exists and is responsible for consuming the document message and producing a collection of messages for onward processing. The Java signature for the, most often, custom Splitter specifies a single object argument and a collection for return. The Recipient List Router - a single router exists, any appropriate router can be used, chose the one that closely matches your requirements - you can easily route by expression or payload type. The primary purpose of the router is route a collection of messages supplied by the splitter. This is a pretty typical Splitter Aggregator configuration. Aggregator - a single construct that is responsible for collecting messages together in a group in order that further processing can take place on the gateway responses. Although the Aggregator can be configured with attributes and bean definitions to provide alternative grouping and release strategies, most often the default aggregation strategy suffices. Interesting Aspects of Splitter Aggregator Operation Gateway - the inbound gateway, the one on the far left, may or may not have an error handling bean reference defined on it. If it does then that bean will have an opportunity to handle an exceptions thrown within the flow to the right of that gateway. If not, any exception will be thrown straight out of the gateway. Gateway - an optional default-reply-timeout can be set on each of the gateways, there are significant implications for setting this value, ensure that they're well understood. An expired timeout will result in a null being returned from the gateway. This is the very same condition that can lead to a thread getting parked if an upstream gateway also has no default-reply-timeout set. Splitter Input Channel - this can be a simple direct channel or a direct channel with a dispatcher defined on it. If the channel has a dispatcher specified the flow downstream of this point will be asynchronous, multi-threaded. This also changes the upstream gateway semantics as it usually means that an otherwise impotent default-reply-timeout becomes active. Splitter - the splitter must return a single object. The single object returned by the splitter is a collection, a java.util.List. The SI framework will take each member of that list and feed it into the output-channel of the Splitter - as with this example, usually straight into a router. The contract for Splitter List returns is as its use in Java - it may contain zero, one or more elements. If the splitter returns an empty list it's unlikely that the router will have any work to do and so the flow invocation will be complete. However, if the List contains one item, the SI framework will extract that item from the list and push it into the router, if this gets routed successfully, the flow will continue. Router - the router will simply route messages into one of two gateways in this example. Gateways - the two gateways that are used between the Splitter and Aggregator are interesting. In this example I have used the generic gateway EIP pattern to represent a message sub-system but not defined it explicitly - we could use an HTTP outbound gateway, another SI flow or any other external system. Of course, for each of those sub-systems, a number of responses is possible. Depending on the protocol and external system, the message request may fail to send, the response fail to arrive, a long running process invoked, a network error or timeout or a general processing exception. Aggregator - the single aggregator will wait for a number of responses depending on what's been created by the Splitter. In the case where the splitter return list is empty the Aggregator will not get invoked. In the case where the Splitter return list has one entry, the aggregator will be waiting for one gateway response to complete the group. In the case where the Splitter list has n entries the Aggregator will be waiting for n entries to complete the group. Custom correlation strategies, release strategies and message stores can be injected amongst a set of rich configuration aspects. Interesting Aspects of Simple Splitter Aggregator Operation The primary deciding factor for establishing whether this type of simple gateway is adequate for requirements is to understand what happens in the event of failure. If any exception occurring in your SI flow results in the flow invocation being abandoned and that suits your requirements, there's no need to read any further. If, however, you need to continue processing following failure in one of the gateways the remainder of this article may be of more interest. Exceptions, from any source, generated between the splitter and aggregator, will result in an empty or partial group being discarded by the Aggregator. The exception will propagate back to the closest upstream gateway for either handling by a custom bean or re-throwing by the gateway. Note that a custom release strategy on the Aggregator is difficult to use and especially so alongside timeouts but would not help in this case as the exception will propagate back to the leftmost gateway before the aggregator is invoked. It's also possible to configure exception handlers on the innermost gateways, the exception message could be caught but how do you route messages from a custom exception handler into the aggregator to complete the group, inject the aggregator channel definition into the custom exception handler? This is a poor approach and would involve unpacking an exception message payload, copying the original message headers into a new SI message and then adding the original payload - only four or five lines of code, but dirty it is. Following exception generation, exception messages (without modification) cannot be routed into an Aggregator to complete the group. The original message, the one that contains the correlation and sequence ids for the group and group position are buried inside the SI messages exception payload. If processing needs to continue following exception generation, it should be clear that in order to continue processing, the following must take place: the aggregation group needs to be completed, any exceptions must be caught and handled before getting back to the closet upstream gateway, the correlation and sequence identifiers that allow group completion in the aggregator are buried within the exception message payload and will require extraction and setting on the message that's bound for the aggregator A More Robust Solution - Messaging Gateway Adapter Pattern Dealing with exceptions and null returns from gateways naturally leads to a design that implements a wrapper around the messaging gateway. This affords a level of control that would otherwise be very difficult to establish. This adapter technique allows all returns from messaging gateways to be caught and processed as the messaging gateway is injected into the Service Activator and called directly from that. The messaging gateway no longer responds to the aggregator directly, it responds to a custom Java code Spring bean configured in the Service Activator namespace definition. As expected, processing that does not undergo exception will continue as normal. Those flows that experience exception conditions or unexpected or missing responses from messaging gateways need to process messages in such as way that message groups bound for aggregation can be completed. If the Service Activator were to allow the exception to be propagated outside of it's backing bean, the group would not complete. The same applies not just for exceptions but any return object that does not carry the prerequisite group correlation id and sequence headers - this is where the adaptation is applied. Exception messages or null responses from messaging gateways are caught and handled as shown in the following example code: import com.l8mdv.sample.*; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.integration.Message; import org.springframework.integration.MessageHeaders; import org.springframework.integration.support.MessageBuilder; import org.springframework.util.Assert; public class AvsServiceImpl implements AvsService { private static final Logger logger = LoggerFactory.getLogger(AvsServiceImpl.class); public static final String MISSING_MANDATORY_ARG = "Mandatory argument is missing."; private AvsGateway avsGateway; public AvsServiceImpl(final AvsGateway avsGateway) { this.avsGateway = avsGateway; } public Message service(Message message) { Assert.notNull(message, MISSING_MANDATORY_ARG); Assert.notNull(message.getPayload(), MISSING_MANDATORY_ARG); MessageHeaders requestMessageHeaders = message.getHeaders(); Message responseMessage = null; try { logger.debug("Entering AVS Gateway"); responseMessage = avsGateway.send(message); if (responseMessage == null) responseMessage = buildNewResponse(requestMessageHeaders, AvsResponseType.NULL_RESULT); logger.debug("Exited AVS Gateway"); return responseMessage; } catch (Exception e) { return buildNewResponse(responseMessage, requestMessageHeaders, AvsResponseType.EXCEPTION_RESULT, e); } } private Message buildNewResponse(MessageHeaders requestMessageHeaders, AvsResponseType avsResponseType) { Assert.notNull(requestMessageHeaders, MISSING_MANDATORY_ARG); Assert.notNull(avsResponseType, MISSING_MANDATORY_ARG); AvsResponse avsResponse = new AvsResponse(); avsResponse.setError(avsResponseType); return MessageBuilder.withPayload(avsResponse) .copyHeadersIfAbsent(requestMessageHeaders).build(); } private Message buildNewResponse(Message responseMessage, MessageHeaders requestMessageHeaders, AvsResponseType avsResponseType, Exception e) { Assert.notNull(responseMessage, MISSING_MANDATORY_ARG); Assert.notNull(responseMessage.getPayload(), MISSING_MANDATORY_ARG); Assert.notNull(requestMessageHeaders, MISSING_MANDATORY_ARG); Assert.notNull(avsResponseType, MISSING_MANDATORY_ARG); Assert.notNull(e, MISSING_MANDATORY_ARG); AvsResponse avsResponse = new AvsResponse(); avsResponse.setError(avsResponseType, responseMessage.getPayload(), e); return MessageBuilder.withPayload(avsResponse) .copyHeadersIfAbsent(requestMessageHeaders).build(); } } Notice the last line of the catch clause of the exception handling block. This line of code copies the correlation and sequence headers into the response message, this is mandatory if the aggregation group is going to be allowed to complete and will always be necessary following an exception as shown here. Consequences of using this technique There's no doubt that introducing a Messaging Gateway Adapter into SI config makes the configuration more complex to read and follow. The key factor here is that there is no longer a linear progression through the configuration file. This because the Service Activator must forward reference a Gateway or a Gateway defined before it's adapting Service Activator - in both cases the result is the same. Resources Note:- The design for the software that drove creation of this meta-pattern was based on a requirement that a number of external risk assessment services would be accessed by a single, central Risk Assessment Service. In order to satisfy clients of the service, invocation had to take place in parallel and continue despite failure in any one of those external services. This requirement lead to the design of the Messaging Gateway Adapter Pattern for the project. Spring Integration Reference Manual The solution approach for this problem was discussed directly with Mark Fisher (SpringSource) in the context of building Risk Assessment flows for a large US financial institution. Although the configuration and code is protected by NDA and copyright, it's acceptable to express the design intention and similar code in this article.

eclipse comes with a large set of different views: they allow the developer to represent the information in various forms and with different angles. most of these views are navigation oriented: a perfect example for this is the projects view or the outline view . but over time i add more projects, more resources to my project, and at a certain time things get overwhelming. i have a lot of projects, and i do not want to switch between workspace too often. yes, i can open and close projects, but this gets cumbersome too. thankfully, there is a solution in eclipse: working sets . working sets allow me to group elements for display in views. with that, i can do operations on a set of elements in that working set. especially as i’m using many projects the same time, working sets are a big help to focus on the right set of things at a time. i can define a set of things i want to look at, work with, or whatever: it allows me to get be productive in the universe of my environment. building/compiling a working set a nice feature of using working sets is to build a set of projects. instead of selecting a set of projects and then to compile them together, i use a working set. i use the menu project > build working set > select working set… to create or change working sets: menu to select working set if i have no working set defined, then this will show the following dialog where i can press new… to create a new one: creating new working set to create a working set of c/c++ projects, i select c/c++ and press next : new c c++ working set next i give a name and select the project(s) which shall be in my working set, and press finish : defining working set to build my set of projects, i can select the working set and press ok : selected working set search in a working set it is possible to limit the search to a working set. for this i can choose a working set as scope in the search dialogs: search in a working set managing working sets to manage working sets, i press ctrl+3 (see quick access ) and choose manage working sets… : ctrl+3 with manage working sets… note: i can add extra tool-bars and menus for working sets too (this is explained later). then i can manage my working sets: manage working set configuration project view filtering with working sets i can filter the projects shown in the project view based on working sets. for this i select the small triangle and select/define a working set or choose one from the most recently used sets: working sets for project view with this i can easily filter and focus on a subset of projects: project view with applied working set really cool tip: i’m using working sets as well to avoid too many workspaces. instead of having projects spread over different workspaces, i can keep them in one workspace and use working sets instead. there is an added benefit of using working sets: having too many projects open at the same time in eclipse can slow down the ide: using working sets allows me just to switch quickly between the set of projects i’m working on. but it does not stop at filtering by projects: you can filter even things inside the project structure. i simply deselect things i don’t want to see and can focus on what is important for me: filtering project files export and import of working sets note: import and export of working sets is not part of the standard codewarrior eclipse distribution. you get the import/export feature installed with the mqx plugins (www.freescale.com/mqx) or with the anyedit plugins (http://andrei.gmxhome.de/anyedit/index.html). to export a working set, i use the menu file > export > other > export working set : export working sets with mqx plugins note: the anyedit plugins come as well with an import/expert working set wizard. the file format is different, and the mqx plugin allows drag&drop of the file into eclipse. this gives the following dialog where i can specify the file name and the root of projects: export working set dialog this will store the settings in an xml file. importing the working set is done with file > import > other > import working set . tip: i’m using *.wsd extension for working sets. that way i can simply drag&drop the file into eclipse to import it. other kinds of working sets working sets do not stop at projects and files: select working set type i can create working sets of breakpoints or analysis/trace points. or i can create working sets of any resource files or tasks. the possibilities are nearly endless and depend as well on the extra plugins installed. window working sets and now back to the really cool part. one question remains: what are window working sets? window working sets the thing is that every view and dialog has its own working set setting. in my example below i use a working set ‘coldfire’ for the projects view, but my search dialog has a ‘kinetis’ working set configured: two different working sets sometimes i want this, but not always. what i need is a ‘global’ working set. and here the window working sets comes to rescue me. for this i’m going to add some menus and toolbars to make it really easy… for this i choose the menu window > customize perspecti ve. in the command groups i enable ‘window working set’. additionally it is a good idea to enable ‘working set manipulation’ as well: window working set commands the same way i can enable the toolbar and menu visibility. this gives me added tool-bars to switch between working sets and to add/remove things from a working set quickly: working set toolbars in a similar way, it gives me menu access as well: working sets menu and here is the trick: using ‘ window working set ‘ really means ‘ using the global workbench working set ‘. to select the global workbench working set, i use the toolbar icon to switch between window (or workbench) working sets: selecting global window or workbench working set in the individual views i choose to use the window working sets instead a selection of working sets: selected global window or workbench working set now my working set settings are shared and common for all views: if i switch the working set, it will switch for all views where i have set it to ‘window working set’: window working set applied to multiple views that way my working set is the same across views, and switching between different project settings is done with a simple mouse click. summary working sets are an extremely powerful feature to get focus on a subset of things inside eclipse, based on my workflow. as with many great eclipse features, i need to know about it until you really appreciate the power of it. who knows how many other hidden treasures are buried in eclipse i hope this article helps to save you a few mouse clicks. happy work-setting but over time i add more projects, more resources to my project, and at a certain time things get overwhelming. i have a lot of projects, and i do not want to switch between workspace too often.

Spring Integration (SI) Gateways Spring Integration Gateways () provide a semantically rich interface to message sub-systems. Gateways are specified using namespace constructs, these reference a specific Java interface () that is backed by an object dynamically implemented at run-time by the Spring Integration framework. Furthermore, these Java interfaces can, if you so wish, be defined entirely independent of any Spring artefacts - that's both code and configuration. One of the primary advantages of using the SI gateway as an interface to message sub-systems is that it's possible to automatically adopt the benefit of rich, default and customisable, gateway configuration. One such configuration attribute deserves further scrutiny and discussion primarily because it's easy to misunderstand and misconfigure around - default-reply-timeout. Primary Motivator for Gateway Analysis During recent consulting engagements, I've encountered a number of deployments that use Spring Integration Gateway specifications that may, in some circumstances, lead to production operational instability. This has often been in high-pressure environments or those where technology support is not backed by adequate training, testing, review or technology mentoring. How do gateways behave in Spring Integration (R2.0.5) One of the key sections, regarding gateways, in the Spring Integration manual clearly explains gateway semantics. Below is a 2-dimensional table of possible non-standard gateway returns for each of the scenarios that the SI Manual (r2.0.5) refers to. Gateway Non-standard Responses Runtime Events default-reply-timeout=x Single-threaded default-reply-timeout=x Multi-threaded default-reply-timeout=null Single-threaded default-reply-timeout=null Multi-threaded 1. Long Running Process Thread Parked null returned Thread Parked Thread Parked 2. Null Returned Downstream null returned null returned Thread Parked Thread Parked 3. void method Downstream null returned null returned Thread Parked Thread Parked 4. Runtime Exception Error handler invoked or exception thrown. Error handler invoked or exception thrown. Error handler invoked or exception thrown. Error handler invoked or exception thrown. The key parts of this table are the conditions that lead to invoking threads being parked (noted in red), nulls returned (noted in orange) and exceptions (noted in green). Each contributor consists of configuration that is under the developers control, deployed code that is under developers control and conditions that are usually not under developers control. Clearly, the column headings in the table above are divided into two sections; two gateway configuration attributes. The default-reply-timeout is set by the SI configured and is the amount of time that a client call is wiling to wait for a response from the gateway. Secondly, synchronous flows are represented by Single-threaded flows, asynchronous by Multi-threaded flows. A synchronous, or single-threaded flow, is one such as the following: The implicit input channel (gateway-request-channel) has no associated dispatcher configured. An asynchronous, or multi-threaded flow, is one such as the following: The explicit input channel has a dispatcher configured ("taskExecutor"). This task executor specifies a thread pool that supplies threads for execution and whose configuration as above marks a thread boundary. Note: This is not the only way of making channels asynchronous The other configuration attribute referenced is default-reply-timeout, this is set on the gateway namespace configuration such as the example above. Note that both of these runtime aspects are set by the configurer during SI flow design and implementation. They are entirely under developer control. The 'Runtime Events' column indicates gateway relevant runtime events that have to be considered during gateway configuration - these are obviously not under developer control. Trigger conditions for these events are not as unusual as one may hope. 1. Long Running Processes It's not uncommon for thread pools to become exhausted because all pooled threads are waiting for an external resource accessed through a socket, this may be a long running database query, a firewall keeping a connection open despite the server terminating etc. There is significant potential for these types of trigger. Some long-running processes terminate naturally, sometimes they never completed - an application restart is required. 2. Null returned downstream A null may be returned from a downstream SI construct such as a Transformer, Service Activator or Gateway. A Gateway may return null in some circumstances such as following a gateway timeout event. 3. Void method downstream Any custom code invoked during an SI flow may use a void method signature. This can also be caused by configuration in circumstances where flows are determined dynamically at runtime. 4. Runtime Exception RuntimeException's can be triggered during normal operation and are generally handled by catching them at the gateway or allowing them to propagate through. The reason that they are coloured green in the table above is that they are generally much easier to handle than timeouts. Gateway Timeout Handling Strategies There are four possible outcomes from invoking a gateway with a request message, all of these as a result of specific runtime events: a) an ordinary message response, b) an exception message, c) a null or d) no-response. Ordinary business responses and exceptions are straight forward to understand and will not be covered further in this article. The two significant outcomes that will be explored further are strategies for dealing with nulls and no-response. Generally speaking, long running processes either terminate or not. Long running processes that terminate may eventually return a message through the invoked gateway or timeout depending on timeout configuration, in which case a null may be returned. The severity of this as a problem depends on throughput volume, length of long running process and system resources (thread-pool size). Configuration exists for default-reply-timeout In the case where a long running process event is underway and a default-reply-timeout has been set, as long as the long running process completes before the default-reply-timeout expires, there is no problem to deal with. However, if the long running process does not complete before that timeout expires one of three outcomes will apply. Firstly, if the long running process terminates subsequent to the reply timeout expiry, the gateway will have already returned null to the invoker so the null response needs handling by the invoker. The thread handling the long-running process will be returned to the pool. Secondly, if the long running process does not terminate and a reply timeout has been set, the gateway will return null to the gateway invoker but the thread executing the long-running process will not get returned to the pool. Thirdly, and most significantly, if a default-reply-timeout has been configured but the long running process is running on the same thread as the invoker, i.e. synchronous channels supply messages to that process, the thread will not return, the default-reply-timeout has no affect. Assuming the most common processing scenario, a long running process completes either before or after the reply timeout expiry. When a null is returned by the gateway, the invoker is forced to deal with a null response. It's often unacceptable to force gateway consumers to deal with null responses and is not necessary as with a little additional configuration, this can be avoided. Absent Configuration for default-reply-timeout The most significant danger exists around gateways that have no default-reply-timeout configuration set. A long running process or a null returned from downstream will mean that the invoking thread is parked. This is true for both synchronous and asynchronous flows and may ultimately force an application to be restarted because the invoker thread pool is likely to start on a depletion course if this continues to occur. Spring Integration Timeout Handling Design Strategies For those Spring Integration configuration designers that are comfortable with gateway invokers dealing with null responses, exceptions and set default-reply-timeouts on gateways, there's no need to read further. However, if you wish to provide clients of your gateway a more predictable response, a couple of strategies exist for handling null responses from gateways in order that invokers are protected from having to deal with them. Firstly, the simpliest solution is to wrap the gateway with a service activator. The gateway must have the default-reply-timeout attribute value set in order to avoid unnecessary parking of threads. In order to avoid the consequence of long-running threads it's also very prudent to use a dispatcher soon after entry to the gateway - this breaks the thread boundary. Whilst this is a valid technical approach, the impact is that we have forced a different entry point to our message sub-system. Entry is now via a Service Activator rather than a Gateway. A side affect of this change is that the testing entry point changes. Integration tests that would normally reference a gateway to send a message now have to locate the backing implementation for the Service Activator, not ideal. An alternative approach toward solving this problem would be to configure two gateways with a Service Activator between them. Only one of the gateways would be exposed to invokers, the outer one. Both Gateways would reference the same service interface. The outer gateway specification would not specify the default-reply-timeout but would specify the input and output channels in the same way that a single gateway would. The Service Activator between the Gateways would handle null gateway responses and possibly any exceptions if preferred to the gateway error handler approach. An example is as follows: The Service Activator bean (enrollmentServiceGatewayHandler) deals with both null and exception responses from the adapted gateway (enrollmentServiceAdaptedGateway), in the situation where these are generated a business response detailing the error is generated. Spring Integration R2.1 Changes async-executor on gateway spec

After my article Connection Pooling in a Java Web Application with Glassfish and NetBeans IDE, here are the instructions for Tomcat. Requirements NetBeans IDE (this tutorial uses NetBeans 7) Tomcat (this tutorial uses Tomcat 7 that is bundled within NetBeans) MySQL database MySQL Java Driver Steps Assuming your MySQL database is ready, connect to it and create a database. Lets call it connpool: mysql> create database connpool; Now we create and populate the table from which we will fetch the data: mysql> use connpool; mysql> create table data(id int(5) not null unique auto_increment, name varchar(255) not null); mysql> insert into data(name) values("Fred Flintstone"), ("Pink Panther"), ("Wayne Cramp"), ("Johnny Bravo"), ("Spongebob Squarepants"); That is it for the database part. We now create our web application. In NetBeans IDE, click File → New Project... Select Java Web → Web Application: Click Next and give the project the name TomPool. Click Next Choose the server as Tomcat and, since we are not going to use any frameworks, click Finish. The project will be created and the start page, index.jsp, opened for us in the IDE. Now we create the connection pooling parameters. In the Projects window, expand configuration files and open "context.xml". You will see that the IDE has added this code for us: Delete the last line: and then add the following to the context.xml file. I have explained the sections along the way. Make sure you edit your MySQL username and password appropriately: Next, expand the Web Pages node, right-click WEB-INF → New → Other → XML → XML Document. Click Next and type web for the File Name. Click next and choose Well-Formed Document then Finish. You will now have the file "web.xml": Delete everything in the file and paste this code: MySQL Test App DB Connection connpool javax.sql.DataSource Container That is it for the connection pool. We now edit our code to make use of it. Edit index.jsp by adding this code just after the initial coments but before Edit the section of the page: Data in my Connection Pooled Database Now, we test the connection pool by running the application: If you want to have the one connection pool used in multiple applications, you need to edit the following two files: 1. /conf/web.xml Just before the closing tag, add the code DB Connection connpool javax.sql.DataSource Container 2. /conf/context.xml Just before the closing tag, add the code Now you can use the pool without editing XML files in each of your applications. Just use the sample code as given in index.jsp That's it folks!