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  • How to get HDD volume id programmatically?

    - by Leandro
    Hi, everybody. I`m programming in obj-c using cocoa, and I would like to discover the HDD volume id programmatically.I know that I will probably need to do this in pure C and than use it in my app, but even in the C language I could not find any answers. Please help.Thanks!

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  • Subsonic Simple Repo for high volume site

    - by kjgilla
    Simple Repo has given me a competitive edge in my consulting. I can finish projects much faster than I could in the "cmd.Parameters.Add(param)" days. As things progress on this end im getting into higher volume sites and wondering if Simple Repo is still the way to go. Im wondering what people's experiences have been putting SR into production vs. NHibernate. Any tips or tricks for using SR in production.

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  • Reduce EBS volume

    - by Martin
    I know about increasing, but is there a way reduce the size of an EBS volume? Like I've put effort into my AMI but soon realized it's way to big for my needs.

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  • Encrypted volume automounting in Mac OS X

    - by nsayer
    I've had a need to create an encrypted volume on my mac for the company source code. The requirements are not terribly stringent: If someone can log into the machine as me, they win, but otherwise, they should lose. With that set of requirements, you can make it so that the disk is automatically mounted at login.

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  • iPhone SDK: How to get mic volume

    - by TheGambler
    I want to get the volume or even how much noise is coming through the mic. So someone is talking or some noise is going on in the background I want to know how much. Which framework would I use: Audio Toolbox, Audio Unit, AV Foundation, and Core Audio

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  • Calculating volume for sphere in c++

    - by Crystal
    This is probably an easy one, but is the right way to calculate volume for a sphere in c++. My getArea() seems to be right, but when I call getVolume() it doesn't output the right amount. With a sphere of radius = 1, it gives me the answer of pi, which is incorrect: double Sphere::getArea() const { return 4 * Shape::pi * pow(getZ(), 2); } double Sphere::getVolume() const { return (4 / 3) * Shape::pi * pow(getZ(), 3); }

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  • How to get the i get the volume GUID

    - by new
    Dear all, I am using win32 api with C++. I would like to know how I can get the volume GUID using a "device path". My device looks like this: \\?\usb#vid_04f2&pid_0111#5&39fe81e&0&2#{a5dcbf10-6530-11d2-901f-00c04fb951ed} Thanks.

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  • Scaling-out Your Services by Message Bus based WCF Transport Extension &ndash; Part 1 &ndash; Background

    - by Shaun
    Cloud computing gives us more flexibility on the computing resource, we can provision and deploy an application or service with multiple instances over multiple machines. With the increment of the service instances, how to balance the incoming message and workload would become a new challenge. Currently there are two approaches we can use to pass the incoming messages to the service instances, I would like call them dispatcher mode and pulling mode.   Dispatcher Mode The dispatcher mode introduces a role which takes the responsible to find the best service instance to process the request. The image below describes the sharp of this mode. There are four clients communicate with the service through the underlying transportation. For example, if we are using HTTP the clients might be connecting to the same service URL. On the server side there’s a dispatcher listening on this URL and try to retrieve all messages. When a message came in, the dispatcher will find a proper service instance to process it. There are three mechanism to find the instance: Round-robin: Dispatcher will always send the message to the next instance. For example, if the dispatcher sent the message to instance 2, then the next message will be sent to instance 3, regardless if instance 3 is busy or not at that moment. Random: Dispatcher will find a service instance randomly, and same as the round-robin mode it regardless if the instance is busy or not. Sticky: Dispatcher will send all related messages to the same service instance. This approach always being used if the service methods are state-ful or session-ful. But as you can see, all of these approaches are not really load balanced. The clients will send messages at any time, and each message might take different process duration on the server side. This means in some cases, some of the service instances are very busy while others are almost idle. For example, if we were using round-robin mode, it could be happened that most of the simple task messages were passed to instance 1 while the complex ones were sent to instance 3, even though instance 1 should be idle. This brings some problem in our architecture. The first one is that, the response to the clients might be longer than it should be. As it’s shown in the figure above, message 6 and 9 can be processed by instance 1 or instance 2, but in reality they were dispatched to the busy instance 3 since the dispatcher and round-robin mode. Secondly, if there are many requests came from the clients in a very short period, service instances might be filled by tons of pending tasks and some instances might be crashed. Third, if we are using some cloud platform to host our service instances, for example the Windows Azure, the computing resource is billed by service deployment period instead of the actual CPU usage. This means if any service instance is idle it is wasting our money! Last one, the dispatcher would be the bottleneck of our system since all incoming messages must be routed by the dispatcher. If we are using HTTP or TCP as the transport, the dispatcher would be a network load balance. If we wants more capacity, we have to scale-up, or buy a hardware load balance which is very expensive, as well as scaling-out the service instances. Pulling Mode Pulling mode doesn’t need a dispatcher to route the messages. All service instances are listening to the same transport and try to retrieve the next proper message to process if they are idle. Since there is no dispatcher in pulling mode, it requires some features on the transportation. The transportation must support multiple client connection and server listening. HTTP and TCP doesn’t allow multiple clients are listening on the same address and port, so it cannot be used in pulling mode directly. All messages in the transportation must be FIFO, which means the old message must be received before the new one. Message selection would be a plus on the transportation. This means both service and client can specify some selection criteria and just receive some specified kinds of messages. This feature is not mandatory but would be very useful when implementing the request reply and duplex WCF channel modes. Otherwise we must have a memory dictionary to store the reply messages. I will explain more about this in the following articles. Message bus, or the message queue would be best candidate as the transportation when using the pulling mode. First, it allows multiple application to listen on the same queue, and it’s FIFO. Some of the message bus also support the message selection, such as TIBCO EMS, RabbitMQ. Some others provide in memory dictionary which can store the reply messages, for example the Redis. The principle of pulling mode is to let the service instances self-managed. This means each instance will try to retrieve the next pending incoming message if they finished the current task. This gives us more benefit and can solve the problems we met with in the dispatcher mode. The incoming message will be received to the best instance to process, which means this will be very balanced. And it will not happen that some instances are busy while other are idle, since the idle one will retrieve more tasks to make them busy. Since all instances are try their best to be busy we can use less instances than dispatcher mode, which more cost effective. Since there’s no dispatcher in the system, there is no bottleneck. When we introduced more service instances, in dispatcher mode we have to change something to let the dispatcher know the new instances. But in pulling mode since all service instance are self-managed, there no extra change at all. If there are many incoming messages, since the message bus can queue them in the transportation, service instances would not be crashed. All above are the benefits using the pulling mode, but it will introduce some problem as well. The process tracking and debugging become more difficult. Since the service instances are self-managed, we cannot know which instance will process the message. So we need more information to support debug and track. Real-time response may not be supported. All service instances will process the next message after the current one has done, if we have some real-time request this may not be a good solution. Compare with the Pros and Cons above, the pulling mode would a better solution for the distributed system architecture. Because what we need more is the scalability, cost-effect and the self-management.   WCF and WCF Transport Extensibility Windows Communication Foundation (WCF) is a framework for building service-oriented applications. In the .NET world WCF is the best way to implement the service. In this series I’m going to demonstrate how to implement the pulling mode on top of a message bus by extending the WCF. I don’t want to deep into every related field in WCF but will highlight its transport extensibility. When we implemented an RPC foundation there are many aspects we need to deal with, for example the message encoding, encryption, authentication and message sending and receiving. In WCF, each aspect is represented by a channel. A message will be passed through all necessary channels and finally send to the underlying transportation. And on the other side the message will be received from the transport and though the same channels until the business logic. This mode is called “Channel Stack” in WCF, and the last channel in the channel stack must always be a transport channel, which takes the responsible for sending and receiving the messages. As we are going to implement the WCF over message bus and implement the pulling mode scaling-out solution, we need to create our own transport channel so that the client and service can exchange messages over our bus. Before we deep into the transport channel, let’s have a look on the message exchange patterns that WCF defines. Message exchange pattern (MEP) defines how client and service exchange the messages over the transportation. WCF defines 3 basic MEPs which are datagram, Request-Reply and Duplex. Datagram: Also known as one-way, or fire-forgot mode. The message sent from the client to the service, and no need any reply from the service. The client doesn’t care about the message result at all. Request-Reply: Very common used pattern. The client send the request message to the service and wait until the reply message comes from the service. Duplex: The client sent message to the service, when the service processing the message it can callback to the client. When callback the service would be like a client while the client would be like a service. In WCF, each MEP represent some channels associated. MEP Channels Datagram IInputChannel, IOutputChannel Request-Reply IRequestChannel, IReplyChannel Duplex IDuplexChannel And the channels are created by ChannelListener on the server side, and ChannelFactory on the client side. The ChannelListener and ChannelFactory are created by the TransportBindingElement. The TransportBindingElement is created by the Binding, which can be defined as a new binding or from a custom binding. For more information about the transport channel mode, please refer to the MSDN document. The figure below shows the transport channel objects when using the request-reply MEP. And this is the datagram MEP. And this is the duplex MEP. After investigated the WCF transport architecture, channel mode and MEP, we finally identified what we should do to extend our message bus based transport layer. They are: Binding: (Optional) Defines the channel elements in the channel stack and added our transport binding element at the bottom of the stack. But we can use the build-in CustomBinding as well. TransportBindingElement: Defines which MEP is supported in our transport and create the related ChannelListener and ChannelFactory. This also defines the scheme of the endpoint if using this transport. ChannelListener: Create the server side channel based on the MEP it’s. We can have one ChannelListener to create channels for all supported MEPs, or we can have ChannelListener for each MEP. In this series I will use the second approach. ChannelFactory: Create the client side channel based on the MEP it’s. We can have one ChannelFactory to create channels for all supported MEPs, or we can have ChannelFactory for each MEP. In this series I will use the second approach. Channels: Based on the MEPs we want to support, we need to implement the channels accordingly. For example, if we want our transport support Request-Reply mode we should implement IRequestChannel and IReplyChannel. In this series I will implement all 3 MEPs listed above one by one. Scaffold: In order to make our transport extension works we also need to implement some scaffold stuff. For example we need some classes to send and receive message though out message bus. We also need some codes to read and write the WCF message, etc.. These are not necessary but would be very useful in our example.   Message Bus There is only one thing remained before we can begin to implement our scaling-out support WCF transport, which is the message bus. As I mentioned above, the message bus must have some features to fulfill all the WCF MEPs. In my company we will be using TIBCO EMS, which is an enterprise message bus product. And I have said before we can use any message bus production if it’s satisfied with our requests. Here I would like to introduce an interface to separate the message bus from the WCF. This allows us to implement the bus operations by any kinds bus we are going to use. The interface would be like this. 1: public interface IBus : IDisposable 2: { 3: string SendRequest(string message, bool fromClient, string from, string to = null); 4:  5: void SendReply(string message, bool fromClient, string replyTo); 6:  7: BusMessage Receive(bool fromClient, string replyTo); 8: } There are only three methods for the bus interface. Let me explain one by one. The SendRequest method takes the responsible for sending the request message into the bus. The parameters description are: message: The WCF message content. fromClient: Indicates if this message was came from the client. from: The channel ID that this message was sent from. The channel ID will be generated when any kinds of channel was created, which will be explained in the following articles. to: The channel ID that this message should be received. In Request-Reply and Duplex MEP this is necessary since the reply message must be received by the channel which sent the related request message. The SendReply method takes the responsible for sending the reply message. It’s very similar as the previous one but no “from” parameter. This is because it’s no need to reply a reply message again in any MEPs. The Receive method takes the responsible for waiting for a incoming message, includes the request message and specified reply message. It returned a BusMessage object, which contains some information about the channel information. The code of the BusMessage class is 1: public class BusMessage 2: { 3: public string MessageID { get; private set; } 4: public string From { get; private set; } 5: public string ReplyTo { get; private set; } 6: public string Content { get; private set; } 7:  8: public BusMessage(string messageId, string fromChannelId, string replyToChannelId, string content) 9: { 10: MessageID = messageId; 11: From = fromChannelId; 12: ReplyTo = replyToChannelId; 13: Content = content; 14: } 15: } Now let’s implement a message bus based on the IBus interface. Since I don’t want you to buy and install the TIBCO EMS or any other message bus products, I will implement an in process memory bus. This bus is only for test and sample purpose. It can only be used if the service and client are in the same process. Very straightforward. 1: public class InProcMessageBus : IBus 2: { 3: private readonly ConcurrentDictionary<Guid, InProcMessageEntity> _queue; 4: private readonly object _lock; 5:  6: public InProcMessageBus() 7: { 8: _queue = new ConcurrentDictionary<Guid, InProcMessageEntity>(); 9: _lock = new object(); 10: } 11:  12: public string SendRequest(string message, bool fromClient, string from, string to = null) 13: { 14: var entity = new InProcMessageEntity(message, fromClient, from, to); 15: _queue.TryAdd(entity.ID, entity); 16: return entity.ID.ToString(); 17: } 18:  19: public void SendReply(string message, bool fromClient, string replyTo) 20: { 21: var entity = new InProcMessageEntity(message, fromClient, null, replyTo); 22: _queue.TryAdd(entity.ID, entity); 23: } 24:  25: public BusMessage Receive(bool fromClient, string replyTo) 26: { 27: InProcMessageEntity e = null; 28: while (true) 29: { 30: lock (_lock) 31: { 32: var entity = _queue 33: .Where(kvp => kvp.Value.FromClient == fromClient && (kvp.Value.To == replyTo || string.IsNullOrWhiteSpace(kvp.Value.To))) 34: .FirstOrDefault(); 35: if (entity.Key != Guid.Empty && entity.Value != null) 36: { 37: _queue.TryRemove(entity.Key, out e); 38: } 39: } 40: if (e == null) 41: { 42: Thread.Sleep(100); 43: } 44: else 45: { 46: return new BusMessage(e.ID.ToString(), e.From, e.To, e.Content); 47: } 48: } 49: } 50:  51: public void Dispose() 52: { 53: } 54: } The InProcMessageBus stores the messages in the objects of InProcMessageEntity, which can take some extra information beside the WCF message itself. 1: public class InProcMessageEntity 2: { 3: public Guid ID { get; set; } 4: public string Content { get; set; } 5: public bool FromClient { get; set; } 6: public string From { get; set; } 7: public string To { get; set; } 8:  9: public InProcMessageEntity() 10: : this(string.Empty, false, string.Empty, string.Empty) 11: { 12: } 13:  14: public InProcMessageEntity(string content, bool fromClient, string from, string to) 15: { 16: ID = Guid.NewGuid(); 17: Content = content; 18: FromClient = fromClient; 19: From = from; 20: To = to; 21: } 22: }   Summary OK, now I have all necessary stuff ready. The next step would be implementing our WCF message bus transport extension. In this post I described two scaling-out approaches on the service side especially if we are using the cloud platform: dispatcher mode and pulling mode. And I compared the Pros and Cons of them. Then I introduced the WCF channel stack, channel mode and the transport extension part, and identified what we should do to create our own WCF transport extension, to let our WCF services using pulling mode based on a message bus. And finally I provided some classes that need to be used in the future posts that working against an in process memory message bus, for the demonstration purpose only. In the next post I will begin to implement the transport extension step by step.   Hope this helps, Shaun All documents and related graphics, codes are provided "AS IS" without warranty of any kind. Copyright © Shaun Ziyan Xu. This work is licensed under the Creative Commons License.

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  • Windows Update can't install Windows Vista SP1

    - by Harry Johnston
    If you install Windows Vista RTM and run Windows Update, many updates are offered and will successfully install. Once all other updates are installed, Windows Vista service pack 1 is offered. When you attempt to install Windows Vista service pack 1, the service pack installation wizard appears, presenting the license agreement and so on. However, shortly after the installation starts the wizard disappears. Windows Update says that the update was installed successfully. However, service pack 1 is not in fact installed, and will be detected as needed again on the next update check. Repeat ad nauseum. On checking the Windows Update log, error 0x80190194 appears near the beginning of an update check, associated with the URL http://update.microsoft.com/vista/windowsupdate/redir/vistawuredir.cab. Why won't service pack 1 install properly and how do I fix it?

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  • How to hide jQuery Sub-Menus(ddsmoothmenu)?

    - by Tim
    I'm new to jQuery and i must admit that i've understood nothing yet, the syntax appears to me as an unknown language although i thought that i had my experiences with javascript. Nevertheless i managed it to implement this menu in my asp.net masterpage's header. Even got it to work that the content-page is loaded with ajax with help from here. But finally i'm failing with the menu to disappear when the new page was loaded asynchronously. I dont know how to hide this accursed jQuery Menu. Following the part of the js-file where the events are registered for hiding/disappearing. I dont know how to get the part that is responsible for it and even i dont know how to implement that part in my Anchor-onclick function where i dont have a reference to the jQuery Object. buildmenu:function($, setting){ var smoothmenu=ddsmoothmenu var $mainmenu=$("#"+setting.mainmenuid+">ul") //reference main menu UL $mainmenu.parent().get(0).className=setting.classname || "ddsmoothmenu" var $headers=$mainmenu.find("ul").parent() $headers.hover( function(e){ $(this).children('a:eq(0)').addClass('selected') }, function(e){ $(this).children('a:eq(0)').removeClass('selected') } ) $headers.each(function(i){ //loop through each LI header var $curobj=$(this).css({zIndex: 100-i}) //reference current LI header var $subul=$(this).find('ul:eq(0)').css({display:'block'}) $subul.data('timers', {}) this._dimensions={w:this.offsetWidth, h:this.offsetHeight, subulw:$subul.outerWidth(), subulh:$subul.outerHeight()} this.istopheader=$curobj.parents("ul").length==1? true : false //is top level header? $subul.css({top:this.istopheader && setting.orientation!='v'? this._dimensions.h+"px" : 0}) $curobj.children("a:eq(0)").css(this.istopheader? {paddingRight: smoothmenu.arrowimages.down[2]} : {}).append( //add arrow images '<img src="'+ (this.istopheader && setting.orientation!='v'? smoothmenu.arrowimages.down[1] : smoothmenu.arrowimages.right[1]) +'" class="' + (this.istopheader && setting.orientation!='v'? smoothmenu.arrowimages.down[0] : smoothmenu.arrowimages.right[0]) + '" style="border:0;" />' ) if (smoothmenu.shadow.enable){ this._shadowoffset={x:(this.istopheader?$subul.offset().left+smoothmenu.shadow.offsetx : this._dimensions.w), y:(this.istopheader? $subul.offset().top+smoothmenu.shadow.offsety : $curobj.position().top)} //store this shadow's offsets if (this.istopheader) $parentshadow=$(document.body) else{ var $parentLi=$curobj.parents("li:eq(0)") $parentshadow=$parentLi.get(0).$shadow } this.$shadow=$('<div class="ddshadow'+(this.istopheader? ' toplevelshadow' : '')+'"></div>').prependTo($parentshadow).css({left:this._shadowoffset.x+'px', top:this._shadowoffset.y+'px'}) //insert shadow DIV and set it to parent node for the next shadow div } $curobj.hover( function(e){ var $targetul=$subul //reference UL to reveal var header=$curobj.get(0) //reference header LI as DOM object clearTimeout($targetul.data('timers').hidetimer) $targetul.data('timers').showtimer=setTimeout(function(){ header._offsets={left:$curobj.offset().left, top:$curobj.offset().top} var menuleft=header.istopheader && setting.orientation!='v'? 0 : header._dimensions.w menuleft=(header._offsets.left+menuleft+header._dimensions.subulw>$(window).width())? (header.istopheader && setting.orientation!='v'? -header._dimensions.subulw+header._dimensions.w : -header._dimensions.w) : menuleft //calculate this sub menu's offsets from its parent if ($targetul.queue().length<=1){ //if 1 or less queued animations $targetul.css({left:menuleft+"px", width:header._dimensions.subulw+'px'}).animate({height:'show',opacity:'show'}, ddsmoothmenu.transition.overtime) if (smoothmenu.shadow.enable){ var shadowleft=header.istopheader? $targetul.offset().left+ddsmoothmenu.shadow.offsetx : menuleft var shadowtop=header.istopheader?$targetul.offset().top+smoothmenu.shadow.offsety : header._shadowoffset.y if (!header.istopheader && ddsmoothmenu.detectwebkit){ //in WebKit browsers, restore shadow's opacity to full header.$shadow.css({opacity:1}) } header.$shadow.css({overflow:'', width:header._dimensions.subulw+'px', left:shadowleft+'px', top:shadowtop+'px'}).animate({height:header._dimensions.subulh+'px'}, ddsmoothmenu.transition.overtime) } } }, ddsmoothmenu.showhidedelay.showdelay) }, function(e){ var $targetul=$subul var header=$curobj.get(0) clearTimeout($targetul.data('timers').showtimer) $targetul.data('timers').hidetimer=setTimeout(function(){ $targetul.animate({height:'hide', opacity:'hide'}, ddsmoothmenu.transition.outtime) if (smoothmenu.shadow.enable){ if (ddsmoothmenu.detectwebkit){ //in WebKit browsers, set first child shadow's opacity to 0, as "overflow:hidden" doesn't work in them header.$shadow.children('div:eq(0)').css({opacity:0}) } header.$shadow.css({overflow:'hidden'}).animate({height:0}, ddsmoothmenu.transition.outtime) } }, ddsmoothmenu.showhidedelay.hidedelay) } ) //end hover }) //end $headers.each() $mainmenu.find("ul").css({display:'none', visibility:'visible'}) } one link of my menu what i want to hide when the content is redirected to another page(i need "closeMenu-function"): <li><a href="DeliveryControl.aspx" onclick="AjaxContent.getContent(this.href);closeMenu();return false;">Delivery Control</a></li> In short: I want to fade out the submenus the same way they do automatically onblur, so that only the headermenu stays visible but i dont know how. Thanks, Tim EDIT: thanks to Starx' private-lesson in jQuery for beginners i solved it: I forgot the # in $("#smoothmenu1"). After that it was not difficult to find and call the hover-function from the menu's headers to let them fade out smoothly: $("#smoothmenu1").find("ul").hover(); Regards, Tim

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  • Don&rsquo;t Miss &ldquo;Transform Field Service Delivery with Oracle Real-Time Scheduler&rdquo;

    - by ruth.donohue
    Field resources are an expensive element in the service equation. Maximizing the scheduling and routing of these resources is critical in reducing costs, increasing profitability, and improving the customer experience. Oracle Real-Time Scheduler creates cost-optimized plans and schedules for service technicians that increase operational efficiencies and improve margins. It enhances Oracle’s Siebel Field Service with real-time scheduling and dispatch capabilities that ensure service requests are allocated efficiently and service levels are honored. Join our live Webcast to learn how your organization can leverage Oracle Real-Time Scheduler to: Increase operational efficiency with real-time scheduling that enables field service technicians to handle more calls per day and reduce travel mileage Resolve issues faster with dynamic work flows that ensure you have the right technician with the right skill set for the right job Improve the customer experience with real-time planning that optimizes field technician routing, reduces customer wait times, and minimizes missed SLAs Date: Thursday, March 10, 2011 Time: 8:30 am PT / 11:30 am ET / 4:30 pm UK / 5:30 pm CET Click here to register now.   Technorati Tags: Siebel Field Service,Oracle Real-Time Scheduler

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  • assembling an object graph without an ORM -- in the service layer or data layer?

    - by Hans Gruber
    At my current gig, our persistence layer uses IBatis going against SQL Server stored procedures (puke). IMHO, this approach has many disadvantages over the use of a "true" ORM such NHibernate or EF, but the one I'm trying to address here revolves around all the boilerplate code needed to map data from a result set into an object graph. Say I have the following DTO object graph I want to return to my presentation layer: IEnumerable<CustomerDTO> |--> IEnumerable<AddressDTO> |--> LatestOrderDTO The way I've implemented this is to have a discrete method in my DAO class to return each IEnumerable<*DTO>, and then have my service class be responsible for orchestrating the calls to the DAO. It then returns the fully assembled object graph to the client: public class SomeService(){ public SomeService(IDao someDao){ this._someDao = someDao; } public IEnumerable<CustomerDTO> ListCustomersForHistory(int brokerId){ var customers = _someDao.ListCustomersForBroker(brokerId); foreach (customer in customers){ customer.Addresses = someDao.ListCustomersAddresses(brokerId); customer.LatestOrder = someDao.GetCustomerLatestOrder(brokerId); } } return customers; } My question is should this logic belong in the service layer or the should I make my DAO such that it instead returns the assembled object graph. If I was using NHibernate, I assume that this kind of relationship association between objects comes for "free"?

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  • New to JEE; architecture suggestions for a service/daemon?

    - by Kate
    I am brand new to the JEE world. As an exercise to try and familiarize myself with JEE, I'm trying to create a tiered web-app, but I'm getting a little stuck on what the best way is to spin up a service in the background that does work. Parameters of the service: It must open and hold a socket connection and receive information from the connected server. There is a 1-to-1 correlation between a user and a new socket connection. So the idea is the user presses a button on the web-page, and somewhere on the server a socket connection is opened. For the remainder of the users session (or until the user presses some sort of disconnect button) the socket remains open and pushes received information to some sort of centralized store that servlets can query and return to the user via AJAX. Is there a JEE type way to handle this situation? Naturally what I would think to do is to just write a Java application that listens on a port that the servlets can connect to and spawns new threads that open these sockets, but that seems very ad-hoc to me. (PS: I am also new to Stack Overflow, so forgive me if it takes me some time to figure the site out!)

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  • New to J2EE; architecture suggestions for a service/daemon?

    - by Kate
    I am brand new to the J2EE world. As an exercise to try and familiarize myself with J2EE, I'm trying to create a tiered web-app, but I'm getting a little stuck on what the best way is to spin up a service in the background that does work. Paramters of the service: It must open and hold a socket connection and receive information from the connected server. There is a 1-to-1 correlation between a user and a new socket connection. So the idea is the user presses a button on the web-page, and somewhere on the server a socket connection is opened. For the remainder of the users session (or until the user presses some sort of disconnect button) the socket remains open and pushes received information to some sort of centralized store that servlets can query and return to the user via AJAX. Is there a J2EE type way to handle this situation? Naturally what I would think to do is to just write a Java application that listens on a port that the servlets can connect to and spawns new threads that open these sockets, but that seems very ad-hoc to me. (PS: I am also new to Stack Overflow, so forgive me if it takes me some time to figure the site out!)

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  • i don't receive mail notification...Nagios Core 4

    - by alessio
    I have a problem with automatically mail notification in Nagios Core 4 installed on ubuntu 12 .04 lts server... i have tried to send mail with nagios user and root user with the command: echo "test" | mail -s "test mail" [email protected] and i received mail correctly... but i don't receive any automatically mail notification... i don't know how can i do to resolve this issue! :( these are my configuration files (commands.cfg, contacts.cfg, nagios.log, mail.log): commands.cfg (the path /usr/bin/mail is the right path): # 'notify-host-by-email' command definition define command{ command_name notify-host-by-email command_line /usr/bin/printf "%b" "***** Nagios *****\n\nNotification Type: $NOTIFICATIONTYPE$\nHost: $HOSTNAME$\nState: $HOSTSTATE$\nAddress: $HOSTADDRESS$\nInfo: $HOSTOUTPUT$\n\nDate/Time: $LONGDATETIME$\n" | /usr/bin/mail -s "** $NOTIFICATIONTYPE$ Host Alert: $HOSTNAME$ is $HOSTSTATE$ **" $CONTACTEMAIL$ } # 'notify-service-by-email' command definition define command{ command_name notify-service-by-email command_line /usr/bin/printf "%b" "***** Nagios *****\n\nNotification Type: $NOTIFICATIONTYPE$\n\nService: $SERVICEDESC$\nHost: $HOSTALIAS$\nAddress: $HOSTADDRESS$\nState: $SERVICESTATE$\n\nDate/Time: $LONGDATETIME$\n\nAdditional Info:\n\n$SERVICEOUTPUT$\n" | /usr/bin/mail -s "** $NOTIFICATIONTYPE$ Service Alert: $HOSTALIAS$/$SERVICEDESC$ is $SERVICESTATE$ **" $CONTACTEMAIL$ } # 'process-host-perfdata' command definition define command{ command_name process-host-perfdata command_line /usr/bin/printf "%b" "$LASTHOSTCHECK$\t$HOSTNAME$\t$HOSTSTATE$\t$HOSTATTEMPT$\t$HOSTSTATETYPE$\t$HOSTEXECUTIONTIME$\t$HOSTOUTPUT$\t$HOSTPERFDATA$\n" >> /usr/local/nagios/var/host-perfdata.out } # 'process-service-perfdata' command definition define command{ command_name process-service-perfdata command_line /usr/bin/printf "%b" "$LASTSERVICECHECK$\t$HOSTNAME$\t$SERVICEDESC$\t$SERVICESTATE$\t$SERVICEATTEMPT$\t$SERVICESTATETYPE$\t$SERVICEEXECUTIONTIME$\t$SERVICELATENCY$\t$SERVICEOUTPUT$\t$SERVICEPERFDATA$\n" >> /usr/local/nagios/var/service-perfdata.out } contacts.cfg: define contact{ contact_name supporto alias Supporto Clienti DEA service_notification_period 24x7 host_notification_period 24x7 service_notification_options w,u,c,r host_notification_options d,r service_notification_commands notify-service-by-email host_notification_commands notify-host-by-email email [email protected] } define contactgroup{ contactgroup_name admins alias Nagios Administrators members supporto } nagios.log: [1401871412] SERVICE ALERT: fileserver;Current Users;OK;SOFT;2;USERS OK - 1 users currently logged in [1401871953] SERVICE ALERT: backups;Nagios Status;WARNING;SOFT;1;NAGIOS WARNING: 36 processes, status log updated 541 seconds ago [1401872133] SERVICE ALERT: backups;Nagios Status;OK;SOFT;2;NAGIOS OK: 36 processes, status log updated 180 seconds ago [1401872321] SERVICE ALERT: posta;Swap Usage;CRITICAL;SOFT;1;CRITICAL - Plugin timed out after 10 seconds [1401872322] SERVICE ALERT: fileserver;Current Users;CRITICAL;SOFT;1;CRITICAL - Plugin timed out after 10 seconds [1401872420] SERVICE ALERT: archivio;Disk Space;CRITICAL;SOFT;1;CRITICAL - Plugin timed out after 10 seconds [1401872492] SERVICE ALERT: fileserver;Current Users;OK;SOFT;2;USERS OK - 1 users currently logged in [1401872492] SERVICE ALERT: posta;Swap Usage;OK;SOFT;2;SWAP OK: 100% free (1984 MB out of 1984 MB) [1401872590] SERVICE ALERT: archivio;Disk Space;OK;SOFT;2;DISK OK [1401872931] Auto-save of retention data completed successfully. [1401873333] SERVICE ALERT: backups;Nagios Status;WARNING;SOFT;1;NAGIOS WARNING: 36 processes, status log updated 402 seconds ago [1401873513] SERVICE ALERT: backups;Nagios Status;OK;SOFT;2;NAGIOS OK: 36 processes, status log updated 180 seconds ago mail.log (i think that the problem is here but i don't know how to resolve it): Jun 4 10:00:01 backups sm-msp-queue[6109]: My unqualified host name (backups) unknown; sleeping for retry Jun 4 10:01:01 backups sm-msp-queue[6109]: unable to qualify my own domain name (backups) -- using short name Jun 4 10:20:01 backups sm-msp-queue[7247]: My unqualified host name (backups) unknown; sleeping for retry Jun 4 10:21:01 backups sm-msp-queue[7247]: unable to qualify my own domain name (backups) -- using short name Jun 4 10:40:01 backups sm-msp-queue[8327]: My unqualified host name (backups) unknown; sleeping for retry Jun 4 10:41:01 backups sm-msp-queue[8327]: unable to qualify my own domain name (backups) -- using short name Jun 4 11:00:01 backups sm-msp-queue[9549]: My unqualified host name (backups) unknown; sleeping for retry Jun 4 11:01:01 backups sm-msp-queue[9549]: unable to qualify my own domain name (backups) -- using short name Jun 4 11:20:01 backups sm-msp-queue[10678]: My unqualified host name (backups) unknown; sleeping for retry Jun 4 11:21:01 backups sm-msp-queue[10678]: unable to qualify my own domain name (backups) -- using short name i'm at the last step and i want to finish this Nagios Core! :) Any help be appreciate!:) host definition (this host have the disk almost full and it is in hard state but non notification) : define host{ use generic-host ; Name of host template to use host_name posta alias Server Posta ESA address 10.10.2.102 parents xen1, xen2 icon_image redhat.png statusmap_image redhat.gd2 } service definition: define service{ use generic-service host_name xen1, maestro, xen2, posta, nas002, serv2, esasrvmi02, esaubuntumi service_description Disk Space check_command ssh_all_disks!10%!5% } Notification is allowed for the contact definition you gave, but is it also allowed at the the service level ? sorry but i don't understand this thing! :(

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  • I'm making a simulated tv

    - by Jam
    I need to make a tv that shows the user the channel and the volume, and shows whether or not the television is on. I have the majority of the code made, but for some reason the channels won't switch. I'm fairly unfamiliar with how properties work, and I think that's what my problem here is. Help please. class Television(object): def __init__(self, __channel=1, volume=1, is_on=0): self.__channel=__channel self.volume=volume self.is_on=is_on def __str__(self): if self.is_on==1: print "The tv is on" print self.__channel print self.volume else: print "The television is off." def toggle_power(self): if self.is_on==1: self.is_on=0 return self.is_on if self.is_on==0: self.is_on=1 return self.is_on def get_channel(self): return channel def set_channel(self, choice): if self.is_on==1: if choice>=0 and choice<=499: channel=self.__channel else: print "Invalid channel!" else: print "The television isn't on!" channel=property(get_channel, set_channel) def raise_volume(self, up=1): if self.is_on==1: self.volume+=up if self.volume>=10: self.volume=10 print "Max volume!" else: print "The television isn't on!" def lower_volume(self, down=1): if self.is_on==1: self.volume-=down if self.volume<=0: self.volume=0 print "Muted!" else: print "The television isn't on!" def main(): tv=Television() choice=None while choice!="0": print \ """ Television 0 - Exit 1 - Toggle Power 2 - Change Channel 3 - Raise Volume 4 - Lower Volume """ choice=raw_input("Choice: ") print if choice=="0": print "Good-bye." elif choice=="1": tv.toggle_power() tv.__str__() elif choice=="2": change=raw_input("What would you like to change the channel to?") tv.set_channel(change) tv.__str__() elif choice=="3": tv.raise_volume() tv.__str__() elif choice=="4": tv.lower_volume() tv.__str__() else: print "\nSorry, but", choice, "isn't a valid choice." main() raw_input("Press enter to exit.")

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