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  • How to make validation for a textbox that accept only comma(,) & digit in asp.net application?

    - by prateeksaluja20
    I am working on a website. I am using C# 2008. I want to make a text box that accept only numbers & comma(,). for example-919981424199,78848817711,47171111747 or there may be a single number like 919981424199. I was able to do one thing My text box only containing number by using this Regular Expression validation.in its property-Validation Expression i wrote "[0-9]+". This is working but now my requirement is to send bulk SMS & each number is separated by (,). I tried a lot but not getting the ans. so please help me to sort out this problem.

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  • How to add sub category on my codeigniter php application ?

    - by sagarmatha
    Hello friends I have a view echo "<label for='parent'>Category</label><br/> "; echo form_dropdown('category_id', $categories). "<p>"; controller function create(){ if($this->input->post('name')){ $this->MProducts->addProduct(); $this->session->set_flashdata('message', 'Products Created'); redirect('admin/products/index', 'refresh'); }else{ $data['title'] = "Create Product"; $data['main'] = 'admin_product_create'; $data['categories']= $this->MCats->getTopCategories(); $this->load->vars($data); $this->load->view('dashboard'); } } and the model is function getTopcategories(){ $data = array(); $data[0] = 'root'; $this->db->where('parentid',0); $Q = $this->db->get('categories'); if($Q->num_rows() > 0){ foreach($Q->result_array() as $row){ $data[$row['id']] = $row['name']; } } $Q->free_result(); return $data; } Basically, what i want is we get sub categories when we click categories and 'selected' subcategory id goes to database when we create products, So that we can list products by sub categories. Please help me how do we do that ?

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  • [C#] Implementing different windows/forms in a Windows Mobile application?

    - by pbean
    I am a bit new to Windows Mobile (with C# and the compact framework) development, so I am kind of unsure how to do this. The user has to go through several pages of information in a wizard-like manner. At the start there is a login window. How would I go about and implement this? Would I just have different User Controls for each page and create/show and destroy/hide them on request? Or do I need to create different forms and somehow show those?

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  • Can two different versions of the same libs (with same name) exists in an application?

    - by Jay
    I have some scenario like this: Product- Platform- mylibs(version-1) Product- mylibs(version-2) i.e Product uses mylibs (version-2) directly. Product also uses platform (which is also a dynamic lib) and platform uses my libs (version-1). The names of the libs used by product and platform are same. Only versions are different and both these versions are not compatible. Is there a way with ".so" libs in linux that Platform can link to one version and product can link to another version of the same libs having the same name?

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  • how to get http responses continuously to a java application?

    - by senrulz
    I have the coding shown below where I have sheduled to get a http response from a php web server page. public static void stopPHPDataChecker() { canStop=true; } public static void main (String args[]) { // http request to the php page and get the response PHPDataChecker pdc = new PHPDataChecker(); ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(1); final ScheduledFuture<?> pdcHandle = scheduler.scheduleAtFixedRate(pdc, 0L, 10L, TimeUnit.MILLISECONDS);// Start schedule scheduler.schedule(new Runnable() { public void run() { System.out.println(">> TRY TO STOP!!!"); pdcHandle.cancel(true); Sheduler.stopPHPDataChecker(); System.out.println("DONE"); } }, 1L, TimeUnit.MILLISECONDS); do { if (canStop) { scheduler.shutdown(); } } while (!canStop); System.out.println("END"); } this coding only returns one response but I want it to get responses continuously so i can do different tasks according to the returned value. how can i do it? Thank you in advance :)

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  • Why doesn’t Office-applications get focus when run from another application on Win 2008?

    - by JohanK
    I have some different COM-Interop examples that when run on Windows 2008 (Office 2007) always open minimized in the task bar. On Windows 2003 or XP they open like I want them to. Has there been any changes to how Windows deals with this? Or to Office? I know that I can close windows with CTRL-SHIFT-ALT, and by that get them to start maximized next time, but for some dialogs this doesn’t work. Is there any way to make them always open maximized or on top? Any clues that could point me in the right direction would be helpful. I have tried with both our VB6 app and a test app in C#.

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  • Top tweets SOA Partner Community – October 2013

    - by JuergenKress
    Send your tweets @soacommunity #soacommunity and follow us at http://twitter.com/soacommunity Ronald Luttikhuizen ?My latest upload: SOA Made Simple | Introduction to SOA on @slideshare http://www.slideshare.net/rluttikhuizen/soa-made-simple-introduction-to-soa … via @SlideShare OTNArchBeat ?ArchBeat Link-o-Rama for October 4, 2013 #cloud #linux #oaam #soa http://pub.vitrue.com/y4SK Lucas Jellema ?My blog article shows news on the new SOA Suite 12c release - as it was publicly available during #oow13 see: http://technology.amis.nl/2013/09/27/oow13-soa-suite-12c/ … Yogesh Sontakke ?Introducing OER's new Express Workflows - Simplified Lifecycle Management. Blog post: http://bit.ly/16JKHCf @soacommunity #soagovernance SrinivasPadmanabhuni ?"@OTNArchBeat: SOA and User Interfaces - by @soacommunity @HajoNormann @gschmutz @t_winterberg et al #industrialsoa http://pub.vitrue.com/KmOp " SOA Community ?SOA and User-Interfaces http://servicetechmag.com/I76/0913-2 article published part of #industrialSOA at Service Technology Magazine #soacommunity Estafet Limited ?@Estafet win @UKOUG Middleware Partner of the Year 2013 Yogesh Sontakke ?RT @VikasAatOracle: #Oracle #B2B - written by experts #soa #soacommunity #oraclesoa - time to get a copy ! @SOAScott Danilo Schmiedel ?Thanks a lot to Juergen @soacommunity for the super interesting and well-organized Partner Advisory Council yesterday! Such a Great Value! OTNArchBeat ?Case management supporting re-landscaping application portfolios | @leonsmiers http://pub.vitrue.com/MC5j Samantha Searle ?Apply for the #GartnerBPM 2014 Excellence Awards - find out how via this link http://ow.ly/ptaNQ #Gartner #bpm #process #entarch #cio OTNArchBeat ?SOA and User Interfaces - by @soacommunity @hajonormann @gschmutz @t_winterberg et al #industrialsoa http://pub.vitrue.com/KmOp Dain Hansen ?Hybrid #cloud is on the rise, but is the IT department's culture standing in the way? http://add.vc/eJN #CloudIntegration #OracleSOA OTNArchBeat #SOASuite 11g ps6 - Download your log files directly from the Enterprise Manager | @whitehorsenl http://pub.vitrue.com/KrJ2 Whitehorses ?Whiteblog: SOA Suite 11g ps6 - Download your log files directly from the Enterprise Manager (http://goo.gl/2Gqiax ) Rajesh Raheja ?Cloud integration session recap #oow13 http://blog.raastech.com/2013/09/recap-of-real-world-cloud-integration.html?m=1 … Vikas Anand ?@Ahmed_Aboulnaga thanks for the excellent summary and kind words. #oow13 #cloud #oraclesoa http://blog.raastech.com/2013/09/recap-of-real-world-cloud-integration.html?m=1 … Luis Augusto Weir ?REST is also SOA. Check it out http://www.soa4u.co.uk/2013/09/restful-is-also-soa.html?m=1 … #soacommunity Graham ?“@OracleBPM & @soacommunity: 5 Ways to Modernize Applications with BPM #AppAdvantage" #oracleday http://bit.ly/15yC6e3 SOA Community ?#ACED director asked me for BPM references in FSI - ever visited my #SOACommunity workspace? https://beehiveonline.oracle.com/teamcollab/overview/SOA_Community_Workspace … #soacommunity #bpm OracleBlogs ?SOA Community Newsletter September 2013 http://ow.ly/2Aj6oK OTNArchBeat ?OOW13: First glimpses of the new #SOASuite12c | @LucasJellema http://pub.vitrue.com/2YgX sbernhardt ?Just published new blog entry on OOW 2013 wrap up. http://thecattlecrew.wordpress.com/2013/09/30/oracle-open-world-2013-wrap-up/ … #oow13 @OC_WIRE @soacommunity Emiel Paasschens ?Home with family after an overwhelming #OOW week in San Francisco with lot of info & meetings. Special thanx to @OracleBelux & @soacommunity Robert van Mölken ?Had a awesome week at #OOW13 in SF. Highlights were the @soacommunity Wine tour, @OracleBelux meet-ups and @OracleSOA CAB. Thanks to all :) SOA Community ?The place Oracle Fusion middleware comes from - Oracle 200 - TKs office - next Oracle 100 - SOA & BPM #soacommunity pic.twitter.com/qibFOQVbRo Oracle BPM ?5 Ways to Modernize Applications with BPM #AppAdvantage http://pub.vitrue.com/l2dn Simon Haslam ?Ha ha - how did we miss that! RT @lucasjellema: Post conference announcement of a new middleware appliance? #oow13 pic.twitter.com/3NvcjPfjXb OTNArchBeat ?The OTNArchBeat Daily is out! http://paper.li/OTNArchBeat/1329828521 … ? Top stories today via @lucasjellema @myfear @TylerJewell Packt Publishing ?Get 50% off ALL our DRM-free eBooks - this weekend only! Go to http://www.packtpub.com/ and use code BIG50, as often as you like! #BIG50 OracleBlogs ?Global Perspective: ACE Director from EMEA Weighs in on AppAdvantage http://ow.ly/2Afek2 orclateamsoa ?#orclateamsoa Blog: BPM Auditing Demystified - I've heard from a couple of customers recently asking about BPM aud... http://ow.ly/2AfbAn AMIS, Oracle & Java ?Cool #soasuite 12c feature managed file transfer - visit Dave Barry at demo point sr212 #oow #soacommunity pic.twitter.com/gb4HLbUarR SOA Community ?Let us know what was best at #OOW @soacommunity save trip home - thanks for coming to #SF ;-) see you at #OOW2014 pic.twitter.com/xbWXjRapqh Lonneke Dikmans ?Nice @dschmied is talking about the different steps in his project. He starts with explaining the user interface design #oow13 #ux #acm Lonneke Dikmans ?Saving the best for the end: managing knowledge worker processes by @dschmied and Prasen.#oow13 #acm cool stuff: adaptive case management Luis Augusto Weir ?SOA Governance is more than just OER. Requires people, processes and tools. Check it out #SOA #soacommunity http://youtu.be/Ohn06smVKVw Lonneke Dikmans ?“@OracleSOA: #oow Join us for:Enterprise SOA Infrastructure Best Practices Thu 9/26 2:00 PM - 3:00 PM Moscone West - 2020 SOA Community ?Business Process Management (BPM) 11g PS6 Awareness Course http://wp.me/p10C8u-1as Ajay Khanna ?Detect, Analyze, Act - Fast! http://wp.me/p10C8u-1ao via @soacommunity #OracleBPM Simone Geib ?It took a while, but I finally reached 500 followers. Thanks everybody and especially @soacommunity :) SOA Community ?Functional Testing Business Processes In Oracle BPM Suite 11g by Arun Pareek http://wp.me/p10C8u-1aq SOA Community Distribute the September edition of the SOA Community newsletter READ it! Didn't receive it register http://www.oracle.com/goto/emea/soa #soacommunity SOA Community ?Detect, Analyze, Act - Fast! by Ajay Khanna http://wp.me/p10C8u-1ao Robert van Mölken ?Finalised my #OOW presentation #CON8736 and live demo on wednesday 25th at 11:45am. Also giving a short version at the SOA CAB on thursday. Rajesh Raheja ?"The AppAdvantage of Oracle Cloud & On-premises Integration" http://bit.ly/14RYHmZ SOA Community ?Additional new content SOA & BPM Partner Community http://wp.me/p10C8u-1aw Dain Hansen ?Right now #oow13 SOA, BPM - Customer Advisory Boards. 'No tweeting' says @SOASimone. Instagram of funny cats still ok. leonsmiers ?Case Management with Oracle BPM Suite our presentation on #oow13 http://www.slideshare.net/leonsmiers/oracle-open-world-2013-case-management-smiers-kitson … #capgemini @nkitson72 Mark Simpson ?Flextronics reduced cost of processing an invoice to <$1 from $7 due to BPM @OracleBPM #oow13 saving millions. Way less than industry avg. Holger Mueller ?#Siemens Shared Services CIO says that #Fusion #Middleware made the difference for #Oracle over #Workday. #Integration matters. #OOW13 oracleopenworld ?Miss any #oow13 keynotes, or simply want to rewatch? Check out the live streaming site for keynotes on demand: http://pub.vitrue.com/RG4D SOA Community ?Analyze your m2m data and act on it! Big data Pattern matching, fast data & soa #soacommunity #oow pic.twitter.com/48Q1z4ckh7 SOA Community ?Top tweets SOA Partner Community – September 2013 http://wp.me/p10C8u-1cR Simone Geib ?#oraclesoa hands on lab at #oow13 pic.twitter.com/IJJrqXIMiu Danilo Schmiedel #oow13 CON8436: Managing Knowledge Worker Processes. Come & get a free Adaptive Case Management poster @soacommunity pic.twitter.com/FRc2CSyLwb John Sim ?Great job again Jurgen @soacommunity helping bring Ace Community together! Danilo Schmiedel ?Excellent #OracleBPM Adaptive Case Management intro by @heidibuelowBPM and Prasen at the #oow13 demo ground.Last chance today @soacommunity SOA Community ?Thanks to all our #bpm #soa and #weblogic partners for the great middleware business #oow #soacommunity pic.twitter.com/dBwZ8DMHfH Whitehorses ?Thanks @soacommunity for the party tonight. Great to meet product management & see all the talented EMEA middleware specialists. #oow13 Danilo Schmiedel ?Great tool demo from Link Consulting about managing your SOA with OER #oow13 @soacommunity Torsten Winterberg ?“@soacommunity: thanks to @dschmied and @OC_WIRE for making it happen to have our case management poster as printed version hier at #oow13 Ronald Luttikhuizen ?These were the architects involved in the diagram excitement :) just after State of SOA podcast with @OTNArchBeat pic.twitter.com/5B8jIrVTA9 SOA Community ?Tanks to AVIO for the excellent #bpmn poster and the great bpm business - visit then at #OOW & get the poster pic.twitter.com/ebTg9pFY1C Dain Hansen ?Kurian introducing Oracle Platform-as-a-Service developments. #oow13 #OracleCloud pic.twitter.com/evJLTU53rx Bruce Tierney ?API Management "multi-level pie chart" at #oow13 by Oracle's Tim Hall pic.twitter.com/q12OIRdaue Dain Hansen ?This is not your Daddy's BAM @soacommunity: Is this BAM? Very cool in #soasuite 12c get a demo at sr225 pic.twitter.com/EvwqXW9U5j SOA Community ?Is this BAM? Very cool in #soasuite 12c get a demo at sr225 pic.twitter.com/LybHxyF362 SOA Community ?SOA governance by @Yogesh_Sontakke at demo point sr214 many good new features - key for soa projects #oow #soa pic.twitter.com/DFK0ummsK1 SOA Community ?Cool #soasuite 12c feature managed file transfer - visit Dave Barry at demo point sr212 #oow #soacommunity pic.twitter.com/GDKcqDGhCF SOA Community ?Adaptive Case Management demo point at #OOW visit @heidibuelowBPM get a demo and cmmn notation poster #soacommunity pic.twitter.com/T7yEyI7tdn Lonneke Dikmans ?In case you missed it: http://blog.vennster.nl/2013/09/case-management-part-1.html?spref=tw … Lucas Jellema ?SOA Suite news: Cloud Adapters RightNow and SalesForce plus SDK to develop custom cloud adapters (CY13); REST/JSON support in SB/SCA (12c) Oracle SOA ?Cloud Integration and AppAdvantage: Transform your Enterprise #soa #oow13 http://pub.vitrue.com/UfPB Dain Hansen ?Cloud Integration and AppAdvantage: Transform your Enterprise #soa #oow13 http://pub.vitrue.com/4QWA Hajo Normann ?#BigData, eventing & real time #analytics suggest timely next actions in #oracleBPM & #oracleACM; #oow13 #FastData pic.twitter.com/aFVGrTXPqu Mark Simpson ?OEP CQL engine now used in BAM12c for event stream summary computation with temporal and pattern match features to feed dashboards. #oow13 Mark Simpson ?BAM12c virtually a new product. Analytics that senses ahead of time and also compares to historical trends to guide process or case #oow13 Andrejus Baranovskis ?Enabling UI Shell 12c/11g Multitasking Behavior http://fb.me/18l9vxQfA Amit Zavery ?Oracle Fusion Middleware Empowers Business Users, EVP Thomas Kurian's session summary http://onforb.es/18Ta1jf #oow13 #oraclemiddle #oracle Vikas Anand ?#oow13 #oracleopenworld BPM on display at Middleware keynote by Thomas Kurian pic.twitter.com/PMm719S0Ui SOA Community ?BPM composer - business user empowerment #oow #soacommunity #bpmsuite pic.twitter.com/0Qgl6oVh0h SOA Community ?Model your process in BPMN - make is executable and analyze & improve them #oow #soacommunity pic.twitter.com/jkLlObDdoi Bruce Tierney ?@demed and Thomas Kurian talk mobile and cloud at #oow13 pic.twitter.com/bAAeqn5a2V Amit Zavery ?Thomas Kurian showcasing all the new features of Oracle Fusion Middleware #oraclemiddle #oow13 SOA Community ?Demo time cloud adapters in #soasuite at Thomas Kurian keynote. Build and integrate mobile apps in minutes #oow pic.twitter.com/qTnCOJLLwS SOA Community ?Soa suite cloud adapters and mobile apps by @demed at Thomas Kurian keynote #oow #oracle #soacommunity pic.twitter.com/5aMLkNH4Ng Danilo Schmiedel ?First impressions from Oracle Open World 2013 http://wp.me/p2fG8x-77 @soacommunity @OC_WIRE SOA Community ?Good morning SFO let us know if you attend #OOW & #OPN keynote - #soacommunity pic.twitter.com/hzLYGDlRgE Simon Haslam ?Had a very useful @wlscommunity PAC meeting yesterday... & probably the best swag to date! pic.twitter.com/Lqus8ysbp7 Vikas Anand ?Oracle SOA Suite - Team Blog http://bit.ly/18I1Zj7 Rajesh Raheja ?Introducing new Cloud Connectivity Adapters #soa #demopod #oow13. I'll be there Sep 23 & 24 3-6pm to meetup http://bit.ly/18I1Zj7 leonsmiers ?..and again a very successful Oracle SOA/BPM partner council on the eve of #oow13. Thanks Jurgen! @soacommunity pic.twitter.com/aM1LMlb7Yw Vikas Anand ?#oow13 #soa #oep #exalogic Canon Delivers Fast Data with Oracle Event Processing (Oracle SOA Suite) http://bit.ly/1dwPeHb #soacommunity Rolf Scheuch ?The ACM poster is a big success. Great talks and .... I am soon out of posters! #bpmcon #ACM pic.twitter.com/TriaUyXRWK Oracle SOA ?British Telecom Sucess with Oracle B2B #oow #soa #b2b http://pub.vitrue.com/1RWi leonsmiers ?(Oracle) Case Management supporting re-platforming, a pre-read before our presentation at #oow13 http://leonsmiers.blogspot.com/2013/09/case-management-supporting-re.html … #capgemini #yammer SOA & BPM Partner CommunityFor regular information on Oracle SOA Suite become a member in the SOA & BPM Partner Community for registration please visit www.oracle.com/goto/emea/soa (OPN account required) If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Facebook Wiki Mix Forum Technorati Tags: Twitter,SOA,Oracle BPM,Community,OPN,Jürgen Kress

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  • Building services with .Net Part 1

    - by Allan Rwakatungu
    On the 26th of May 2010 , I made a presentation to the .NET user group meeting (thanks to Malisa Ncube for organizing this event every month … ). If you missed my presentation , we talked about why we should all be building services … better still using the .NET framework. This blog post is an introduction to services , why you would want to build services and how you can build services using the .NET framework. What is a service? OASIS defines service as "a mechanism to enable access to one or more capabilities, where the access is provided using a prescribed interface and is exercised consistent with constraints and policies as specified by the service description." [1]. If the above definition sounds to academic , you can also define a service as loosely coupled units of functionality that have no calls to each other embedded in the. Instead of services embedding calls to each other in their service code they use defined protocols that describe how services pass and parse messages. This is a good way to think about services if you’re from an objected oriented background. While in object oriented programming functions make calls to each other, in service oriented programming, functions pass messages between each other. Why would you want to use services? 1. If your enterprise architecture looks like this   Services are the building blocks for SOA . With SOA you can move away from the sphaggetti infrastructure that is common in most enterprises. The complexity or lack of visibility of the integration points in your enterprises makes it difficult and costly to implement new initiatives and changes into the business - and even impossible in some cases - as it is not possible to identify the impact a change in one system might have to other systems. With services you can move to an architecture like this Your building blocks from Spaghetti infrastructure to something that is more well-defined and manageable to achieve cost efficiency and not least business agility - enabling you to react to changes in the market with speed and achieve operational efficiency and control are services. 2. If you want to become the Gates or Zuckerburger. Have you heard about Web 2.0 ? Mashups? Software as a service (SAAS) ? Cloud computing ?   They all offer you the opportunity to have scalable but low cost business models and they built using services.  Some of my favorite companies that leverage services for their business models include  https://www.salesforce.com/ (cloud CRM) http://www. twitter.com (more people use twitter clients built by 3rd parties than their official clients) http://www.kayak.com/ (compares data from other travel sites to give information to users in one location) Services with the .NET framework      If you are a .NET developer and you want to develop services, Windows Communication Framework (WCF) is the tool for you. WCF is Microsoft’s unified programming model (service model) for building service oriented applications. ( Before .NET 3.0 you had several models for programming services in .NET including .NET remoting, Web services (ASMX), COM +, Microsoft Messaging queuing (MSMQ) etc, after .NET 3.0 the programming model was unified into one i.e. WCF ). Windows Communication Framework (WCF) provides you 1. An Software Development Kit (SDK) for creating SOA applications 2. A runtime for running services on the Windows platform Why should you use Windows Communication Foundation if you’re programming services?   1. It supports interoperable and open standards e.g. WS* protocols for programming SOAP services 2. It has a unified programming model. Whether you use TCP or Http or Pipes or transmitting using Messaging Queues, programmers need to learn just one way to program. Previously you had .NET remoting, MSMQ, Web services, COM+ and they were all done differently 3. Productive programming model You don’t have to worry about all the plumbing involved to write services. You have a rich declarative programming model to add stuff like logging, transactions, and reliable messages in-built in the Windows Communication Framework. Understanding services in WCF The basic principles of WCF are as easy as ABC A – Address This is where the service is located B- Binding This describes how you communicate with the service e.g. Use TCP, HTTP or both. How to exchange security information with the service etc. C – Contract This defines what the service can do. E.g. Pay water bill, Make a phone call A - Addresses In WCF, an address is a combination of transport, server name, port and path Example addresses may include http://localhost:8001 net.tcp://localhost:8002/MyService net.pipe://localhost/MyPipe net.msmq://localhost/private/MyService net.msmq://localhost/MyService B- Binding   There are numerous ways to communicate with services , different ways that a message can be formatted/sent/secured, that allows you to tailor your service for the compatibility/performance you require for your solution. Transport You can use HTTP TCP MSMQ , Named pipes, Your own custom transport etc Message You  can send a plain text binary, Message Transmission Optimization Mechanism (MTOM) message Communication security No security Transport security Message security Authenticating and authorizing callers etc Behaviour You service can support Transactions Be reliable Use queues Support ajax etc C - Contract You define what your service can do using Service contracts :- Define operations that your service can do, communications and behaviours Data contracts :- Define the messages that are passed from and into your service and how they are formatted Fault contracts :- Defines errors types in your service   As an example, suppose your service service shows money. You define your service contract using a interface [ServiceContract] public interface IShowMeTheMoney {   [OperationContract]    Money Show(); } You define the data contract by annotating a class it with the Data Contract attribute and fields you want to pass in the message as Data Members. (Note:- In the latest versions of WCF you dont have to use attributes if you passing all the objects properties in the message) [DataContract] public Money {   [DataMember]   public string Currency { get; set; }   [DataMember]   public Decimal Amount { get; set; }   public string Comment { get; set; } } Features of Windows Communication Foundation Windows Communication Foundation is not only simple but feature rich , offering you several options to tweak your service to fit your business requirements. Some of the features of WCF include 1. Workflow services You can combine WCF with Windows WorkFlow Foundation (WWF) to write workflow type services 2. Control how your data (messages) are transferred and serialized e.g. you can serialize your business objects as XML or binary 3. control over session management , instance creation and concurrency management without writing code if you like 4. Queues and reliable sessions. You can store messages from the sending client and later forward them to the receiving application. You can also guarantee that messages will arrive at their destincation. 5.Transactions:  You can have different services participate in a transaction operations that can be rolled back if needed 6. Security. WCF has rich features for authorization and authentication  as well as keep audit trails 7. Web programming model. WCF allows developers to expose services as non SOAP endpoints 8. Inbuilt features that you can use to write JSON and services that support AJAX applications And lots more In my next blog I will show you how you can use WCF features to write a real world business service.               Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 ]] /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

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  • Code Reuse is (Damn) Hard

    - by James Michael Hare
    Being a development team lead, the task of interviewing new candidates was part of my job.  Like any typical interview, we started with some easy questions to get them warmed up and help calm their nerves before hitting the hard stuff. One of those easier questions was almost always: “Name some benefits of object-oriented development.”  Nearly every time, the candidate would chime in with a plethora of canned answers which typically included: “it helps ease code reuse.”  Of course, this is a gross oversimplification.  Tools only ease reuse, its developers that ultimately can cause code to be reusable or not, regardless of the language or methodology. But it did get me thinking…  we always used to say that as part of our mantra as to why Object-Oriented Programming was so great.  With polymorphism, inheritance, encapsulation, etc. we in essence set up the concepts to help facilitate reuse as much as possible.  And yes, as a developer now of many years, I unquestionably held that belief for ages before it really struck me how my views on reuse have jaded over the years.  In fact, in many ways Agile rightly eschews reuse as taking a backseat to developing what's needed for the here and now.  It used to be I was in complete opposition to that view, but more and more I've come to see the logic in it.  Too many times I've seen developers (myself included) get lost in design paralysis trying to come up with the perfect abstraction that would stand all time.  Nearly without fail, all of these pieces of code become obsolete in a matter of months or years. It’s not that I don’t like reuse – it’s just that reuse is hard.  In fact, reuse is DAMN hard.  Many times it is just a distraction that eats up architect and developer time, and worse yet can be counter-productive and force wrong decisions.  Now don’t get me wrong, I love the idea of reusable code when it makes sense.  These are in the few cases where you are designing something that is inherently reusable.  The problem is, most business-class code is inherently unfit for reuse! Furthermore, the code that is reusable will often fail to be reused if you don’t have the proper framework in place for effective reuse that includes standardized versioning, building, releasing, and documenting the components.  That should always be standard across the board when promoting reusable code.  All of this is hard, and it should only be done when you have code that is truly reusable or you will be exerting a large amount of development effort for very little bang for your buck. But my goal here is not to get into how to reuse (that is a topic unto itself) but what should be reused.  First, let’s look at an extension method.  There’s many times where I want to kick off a thread to handle a task, then when I want to reign that thread in of course I want to do a Join on it.  But what if I only want to wait a limited amount of time and then Abort?  Well, I could of course write that logic out by hand each time, but it seemed like a great extension method: 1: public static class ThreadExtensions 2: { 3: public static bool JoinOrAbort(this Thread thread, TimeSpan timeToWait) 4: { 5: bool isJoined = false; 6:  7: if (thread != null) 8: { 9: isJoined = thread.Join(timeToWait); 10:  11: if (!isJoined) 12: { 13: thread.Abort(); 14: } 15: } 16: return isJoined; 17: } 18: } 19:  When I look at this code, I can immediately see things that jump out at me as reasons why this code is very reusable.  Some of them are standard OO principles, and some are kind-of home grown litmus tests: Single Responsibility Principle (SRP) – The only reason this extension method need change is if the Thread class itself changes (one responsibility). Stable Dependencies Principle (SDP) – This method only depends on classes that are more stable than it is (System.Threading.Thread), and in itself is very stable, hence other classes may safely depend on it. It is also not dependent on any business domain, and thus isn't subject to changes as the business itself changes. Open-Closed Principle (OCP) – This class is inherently closed to change. Small and Stable Problem Domain – This method only cares about System.Threading.Thread. All-or-None Usage – A user of a reusable class should want the functionality of that class, not parts of that functionality.  That’s not to say they most use every method, but they shouldn’t be using a method just to get half of its result. Cost of Reuse vs. Cost to Recreate – since this class is highly stable and minimally complex, we can offer it up for reuse very cheaply by promoting it as “ready-to-go” and already unit tested (important!) and available through a standard release cycle (very important!). Okay, all seems good there, now lets look at an entity and DAO.  I don’t know about you all, but there have been times I’ve been in organizations that get the grand idea that all DAOs and entities should be standardized and shared.  While this may work for small or static organizations, it’s near ludicrous for anything large or volatile. 1: namespace Shared.Entities 2: { 3: public class Account 4: { 5: public int Id { get; set; } 6:  7: public string Name { get; set; } 8:  9: public Address HomeAddress { get; set; } 10:  11: public int Age { get; set;} 12:  13: public DateTime LastUsed { get; set; } 14:  15: // etc, etc, etc... 16: } 17: } 18:  19: ... 20:  21: namespace Shared.DataAccess 22: { 23: public class AccountDao 24: { 25: public Account FindAccount(int id) 26: { 27: // dao logic to query and return account 28: } 29:  30: ... 31:  32: } 33: } Now to be fair, I’m not saying there doesn’t exist an organization where some entites may be extremely static and unchanging.  But at best such entities and DAOs will be problematic cases of reuse.  Let’s examine those same tests: Single Responsibility Principle (SRP) – The reasons to change for these classes will be strongly dependent on what the definition of the account is which can change over time and may have multiple influences depending on the number of systems an account can cover. Stable Dependencies Principle (SDP) – This method depends on the data model beneath itself which also is largely dependent on the business definition of an account which can be very inherently unstable. Open-Closed Principle (OCP) – This class is not really closed for modification.  Every time the account definition may change, you’d need to modify this class. Small and Stable Problem Domain – The definition of an account is inherently unstable and in fact may be very large.  What if you are designing a system that aggregates account information from several sources? All-or-None Usage – What if your view of the account encompasses data from 3 different sources but you only care about one of those sources or one piece of data?  Should you have to take the hit of looking up all the other data?  On the other hand, should you have ten different methods returning portions of data in chunks people tend to ask for?  Neither is really a great solution. Cost of Reuse vs. Cost to Recreate – DAOs are really trivial to rewrite, and unless your definition of an account is EXTREMELY stable, the cost to promote, support, and release a reusable account entity and DAO are usually far higher than the cost to recreate as needed. It’s no accident that my case for reuse was a utility class and my case for non-reuse was an entity/DAO.  In general, the smaller and more stable an abstraction is, the higher its level of reuse.  When I became the lead of the Shared Components Committee at my workplace, one of the original goals we looked at satisfying was to find (or create), version, release, and promote a shared library of common utility classes, frameworks, and data access objects.  Now, of course, many of you will point to nHibernate and Entity for the latter, but we were looking at larger, macro collections of data that span multiple data sources of varying types (databases, web services, etc). As we got deeper and deeper in the details of how to manage and release these items, it quickly became apparent that while the case for reuse was typically a slam dunk for utilities and frameworks, the data access objects just didn’t “smell” right.  We ended up having session after session of design meetings to try and find the right way to share these data access components. When someone asked me why it was taking so long to iron out the shared entities, my response was quite simple, “Reuse is hard...”  And that’s when I realized, that while reuse is an awesome goal and we should strive to make code maintainable, often times you end up creating far more work for yourself than necessary by trying to force code to be reusable that inherently isn’t. Think about classes the times you’ve worked in a company where in the design session people fight over the best way to implement a class to make it maximally reusable, extensible, and any other buzzwordable.  Then think about how quickly that design became obsolete.  Many times I set out to do a project and think, “yes, this is the best design, I can extend it easily!” only to find out the business requirements change COMPLETELY in such a way that the design is rendered invalid.  Code, in general, tends to rust and age over time.  As such, writing reusable code can often be difficult and many times ends up being a futile exercise and worse yet, sometimes makes the code harder to maintain because it obfuscates the design in the name of extensibility or reusability. So what do I think are reusable components? Generic Utility classes – these tend to be small classes that assist in a task and have no business context whatsoever. Implementation Abstraction Frameworks – home-grown frameworks that try to isolate changes to third party products you may be depending on (like writing a messaging abstraction layer for publishing/subscribing that is independent of whether you use JMS, MSMQ, etc). Simplification and Uniformity Frameworks – To some extent this is similar to an abstraction framework, but there may be one chosen provider but a development shop mandate to perform certain complex items in a certain way.  Or, perhaps to simplify and dumb-down a complex task for the average developer (such as implementing a particular development-shop’s method of encryption). And what are less reusable? Application and Business Layers – tend to fluctuate a lot as requirements change and new features are added, so tend to be an unstable dependency.  May be reused across applications but also very volatile. Entities and Data Access Layers – these tend to be tuned to the scope of the application, so reusing them can be hard unless the abstract is very stable. So what’s the big lesson?  Reuse is hard.  In fact it’s damn hard.  And much of the time I’m not convinced we should focus too hard on it. If you’re designing a utility or framework, then by all means design it for reuse.  But you most also really set down a good versioning, release, and documentation process to maximize your chances.  For anything else, design it to be maintainable and extendable, but don’t waste the effort on reusability for something that most likely will be obsolete in a year or two anyway.

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  • Reference Data Management

    - by rahulkamath
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} table.MsoTableColorfulListAccent2 {mso-style-name:"Colorful List - Accent 2"; mso-tstyle-rowband-size:1; mso-tstyle-colband-size:1; mso-style-priority:72; mso-style-unhide:no; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-tstyle-shading:#F8EDED; mso-tstyle-shading-themecolor:accent2; mso-tstyle-shading-themetint:25; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif"; color:black; mso-themecolor:text1;} table.MsoTableColorfulListAccent2FirstRow {mso-style-name:"Colorful List - Accent 2"; mso-table-condition:first-row; mso-style-priority:72; mso-style-unhide:no; mso-tstyle-shading:#9E3A38; mso-tstyle-shading-themecolor:accent2; mso-tstyle-shading-themeshade:204; mso-tstyle-border-bottom:1.5pt solid white; mso-tstyle-border-bottom-themecolor:background1; color:white; mso-themecolor:background1; mso-ansi-font-weight:bold; mso-bidi-font-weight:bold;} table.MsoTableColorfulListAccent2LastRow {mso-style-name:"Colorful List - Accent 2"; mso-table-condition:last-row; mso-style-priority:72; mso-style-unhide:no; mso-tstyle-shading:white; mso-tstyle-shading-themecolor:background1; mso-tstyle-border-top:1.5pt solid black; mso-tstyle-border-top-themecolor:text1; color:#9E3A38; mso-themecolor:accent2; mso-themeshade:204; mso-ansi-font-weight:bold; mso-bidi-font-weight:bold;} table.MsoTableColorfulListAccent2FirstCol {mso-style-name:"Colorful List - Accent 2"; mso-table-condition:first-column; mso-style-priority:72; mso-style-unhide:no; mso-ansi-font-weight:bold; mso-bidi-font-weight:bold;} table.MsoTableColorfulListAccent2LastCol {mso-style-name:"Colorful List - Accent 2"; mso-table-condition:last-column; mso-style-priority:72; mso-style-unhide:no; mso-ansi-font-weight:bold; mso-bidi-font-weight:bold;} table.MsoTableColorfulListAccent2OddColumn {mso-style-name:"Colorful List - Accent 2"; mso-table-condition:odd-column; mso-style-priority:72; mso-style-unhide:no; mso-tstyle-shading:#EFD3D2; mso-tstyle-shading-themecolor:accent2; mso-tstyle-shading-themetint:63; mso-tstyle-border-top:cell-none; mso-tstyle-border-left:cell-none; mso-tstyle-border-bottom:cell-none; mso-tstyle-border-right:cell-none; mso-tstyle-border-insideh:cell-none; mso-tstyle-border-insidev:cell-none;} table.MsoTableColorfulListAccent2OddRow {mso-style-name:"Colorful List - Accent 2"; mso-table-condition:odd-row; mso-style-priority:72; mso-style-unhide:no; mso-tstyle-shading:#F2DBDB; mso-tstyle-shading-themecolor:accent2; mso-tstyle-shading-themetint:51;} Reference Data Management Oracle Data Relationship Management (DRM) has always been extremely powerful as an Enterprise MDM solution that can help manage changes to master data in a way that influences enterprise structure, whether it be mastering chart of accounts to enable financial transformation, or revamping organization structures to drive business transformation and operational efficiencies, or mastering sales territories in light of rapid fire acquisitions that require frequent sales territory refinement, equitable distribution of leads and accounts to salespersons, and alignment of budget/forecast with results to optimize sales coverage. Increasingly, DRM is also being utilized by Oracle customers for reference data management, an emerging solution space that deserves some explanation. What is reference data? Reference data is a close cousin of master data. While master data may be more rapidly changing, requires consensus building across stakeholders and lends structure to business transactions, reference data is simpler, more slowly changing, but has semantic content that is used to categorize or group other information assets – including master data – and give them contextual value. The following table contains an illustrative list of examples of reference data by type. Reference data types may include types and codes, business taxonomies, complex relationships & cross-domain mappings or standards. Types & Codes Taxonomies Relationships / Mappings Standards Transaction Codes Industry Classification Categories and Codes, e.g., North America Industry Classification System (NAICS) Product / Segment; Product / Geo Calendars (e.g., Gregorian, Fiscal, Manufacturing, Retail, ISO8601) Lookup Tables (e.g., Gender, Marital Status, etc.) Product Categories City à State à Postal Codes Currency Codes (e.g., ISO) Status Codes Sales Territories (e.g., Geo, Industry Verticals, Named Accounts, Federal/State/Local/Defense) Customer / Market Segment; Business Unit / Channel Country Codes (e.g., ISO 3166, UN) Role Codes Market Segments Country Codes / Currency Codes / Financial Accounts Date/Time, Time Zones (e.g., ISO 8601) Domain Values Universal Standard Products and Services Classification (UNSPSC), eCl@ss International Classification of Diseases (ICD) e.g., ICD9 à IC10 mappings Tax Rates Why manage reference data? Reference data carries contextual value and meaning and therefore its use can drive business logic that helps execute a business process, create a desired application behavior or provide meaningful segmentation to analyze transaction data. Further, mapping reference data often requires human judgment. Sample Use Cases of Reference Data Management Healthcare: Diagnostic Codes The reference data challenges in the healthcare industry offer a case in point. Part of being HIPAA compliant requires medical practitioners to transition diagnosis codes from ICD-9 to ICD-10, a medical coding scheme used to classify diseases, signs and symptoms, causes, etc. The transition to ICD-10 has a significant impact on business processes, procedures, contracts, and IT systems. Since both code sets ICD-9 and ICD-10 offer diagnosis codes of very different levels of granularity, human judgment is required to map ICD-9 codes to ICD-10. The process requires collaboration and consensus building among stakeholders much in the same way as does master data management. Moreover, to build reports to understand utilization, frequency and quality of diagnoses, medical practitioners may need to “cross-walk” mappings -- either forward to ICD-10 or backwards to ICD-9 depending upon the reporting time horizon. Spend Management: Product, Service & Supplier Codes Similarly, as an enterprise looks to rationalize suppliers and leverage their spend, conforming supplier codes, as well as product and service codes requires supporting multiple classification schemes that may include industry standards (e.g., UNSPSC, eCl@ss) or enterprise taxonomies. Aberdeen Group estimates that 90% of companies rely on spreadsheets and manual reviews to aggregate, classify and analyze spend data, and that data management activities account for 12-15% of the sourcing cycle and consume 30-50% of a commodity manager’s time. Creating a common map across the extended enterprise to rationalize codes across procurement, accounts payable, general ledger, credit card, procurement card (P-card) as well as ACH and bank systems can cut sourcing costs, improve compliance, lower inventory stock, and free up talent to focus on value added tasks. Specialty Finance: Point of Sales Transaction Codes and Product Codes In the specialty finance industry, enterprises are confronted with usury laws – governed at the state and local level – that regulate financial product innovation as it relates to consumer loans, check cashing and pawn lending. To comply, it is important to demonstrate that transactions booked at the point of sale are posted against valid product codes that were on offer at the time of booking the sale. Since new products are being released at a steady stream, it is important to ensure timely and accurate mapping of point-of-sale transaction codes with the appropriate product and GL codes to comply with the changing regulations. Multi-National Companies: Industry Classification Schemes As companies grow and expand across geographies, a typical challenge they encounter with reference data represents reconciling various versions of industry classification schemes in use across nations. While the United States, Mexico and Canada conform to the North American Industry Classification System (NAICS) standard, European Union countries choose different variants of the NACE industry classification scheme. Multi-national companies must manage the individual national NACE schemes and reconcile the differences across countries. Enterprises must invest in a reference data change management application to address the challenge of distributing reference data changes to downstream applications and assess which applications were impacted by a given change.

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  • Rails Passenger Nginx cannot load such file -- bundler

    - by Stuart
    I have set up Rails, Passenger, nginx, and PostgreSQL on Ubuntu Server 12.04LTS. Upon trying to access the application/website, however, I am greeted with an error page saying that the application could not be started because a source file is missing. Error message: cannot load such file -- bundler. My nginx config (/opt/nginx/conf/nginx.conf): user railsapp; worker_processes 1; events { worker_connections 1024; } http { include mime.types; default_type application/octet-stream; sendfile on; keepalive_timeout 65; passenger_root /home/railsapp/.rvm/gems/ruby-1.9.3-p194/gems/passenger-3.0.14; passenger_ruby /home/railsapp/.rvm/rubies/ruby-1.9.3-p194/bin/ruby; server { listen 80; server_name fitness_schedules.local; root /home/railsapp/fitness_schedules/public; passenger_enabled on; rack_env development; } } Here is the error message: A source file that the application requires, is missing. It is possible that you didn't upload your application files correctly. Please check whether all your application files are uploaded. A required library may not installed. Please install all libraries that this application requires. Further information about the error may have been written to the application's log file. Please check it in order to analyse the problem. Error message: cannot load such file -- bundler Exception class: LoadError Application root: /home/railsapp/fitness_schedules Here is the backtrace from the webpage that is presented by nginx: Backtrace: # File Line Location 0 /home/railsapp/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb 36 in `require' 1 /home/railsapp/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb 36 in `require' 2 /home/railsapp/.rvm/gems/ruby-1.9.3-p194/gems/passenger-3.0.14/lib/phusion_passenger/utils.rb 325 in `prepare_app_process' 3 /home/railsapp/.rvm/gems/ruby-1.9.3-p194/gems/passenger-3.0.14/lib/phusion_passenger/rack/application_spawner.rb 156 in `block in initialize_server' 4 /home/railsapp/.rvm/gems/ruby-1.9.3-p194/gems/passenger-3.0.14/lib/phusion_passenger/utils.rb 563 in `report_app_init_status' 5 /home/railsapp/.rvm/gems/ruby-1.9.3-p194/gems/passenger-3.0.14/lib/phusion_passenger/rack/application_spawner.rb 154 in `initialize_server' 6 /home/railsapp/.rvm/gems/ruby-1.9.3-p194/gems/passenger-3.0.14/lib/phusion_passenger/abstract_server.rb 204 in `start_synchronously' 7 /home/railsapp/.rvm/gems/ruby-1.9.3-p194/gems/passenger-3.0.14/lib/phusion_passenger/abstract_server.rb 180 in `start' 8 /home/railsapp/.rvm/gems/ruby-1.9.3-p194/gems/passenger-3.0.14/lib/phusion_passenger/rack/application_spawner.rb 129 in `start' 9 /home/railsapp/.rvm/gems/ruby-1.9.3-p194/gems/passenger-3.0.14/lib/phusion_passenger/spawn_manager.rb 253 in `block (2 levels) in spawn_rack_application' 10 /home/railsapp/.rvm/gems/ruby-1.9.3-p194/gems/passenger-3.0.14/lib/phusion_passenger/abstract_server_collection.rb 132 in `lookup_or_add' 11 /home/railsapp/.rvm/gems/ruby-1.9.3-p194/gems/passenger-3.0.14/lib/phusion_passenger/spawn_manager.rb 246 in `block in spawn_rack_application' 12 /home/railsapp/.rvm/gems/ruby-1.9.3-p194/gems/passenger-3.0.14/lib/phusion_passenger/abstract_server_collection.rb 82 in `block in synchronize' 13 prelude> 10:in `synchronize' 14 /home/railsapp/.rvm/gems/ruby-1.9.3-p194/gems/passenger-3.0.14/lib/phusion_passenger/abstract_server_collection.rb 79 in `synchronize' 15 /home/railsapp/.rvm/gems/ruby-1.9.3-p194/gems/passenger-3.0.14/lib/phusion_passenger/spawn_manager.rb 244 in `spawn_rack_application' 16 /home/railsapp/.rvm/gems/ruby-1.9.3-p194/gems/passenger-3.0.14/lib/phusion_passenger/spawn_manager.rb 137 in `spawn_application' 17 /home/railsapp/.rvm/gems/ruby-1.9.3-p194/gems/passenger-3.0.14/lib/phusion_passenger/spawn_manager.rb 275 in `handle_spawn_application' 18 /home/railsapp/.rvm/gems/ruby-1.9.3-p194/gems/passenger-3.0.14/lib/phusion_passenger/abstract_server.rb 357 in `server_main_loop' 19 /home/railsapp/.rvm/gems/ruby-1.9.3-p194/gems/passenger-3.0.14/lib/phusion_passenger/abstract_server.rb 206 in `start_synchronously' 20 /home/railsapp/.rvm/gems/ruby-1.9.3-p194/gems/passenger-3.0.14/helper-scripts/passenger-spawn-server 99 in `' In ~/fitness_schedules/log there are only development and test logs, no production/development logs.

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  • PC runs very slowly for no apparent reason

    - by GalacticCowboy
    I have a Dell Latitude D820 that I've owned for about 2.5 years. It is a Core 2 Duo T7200 2.0GHz, with 2 GB of RAM, an 80 GB hard drive and an NVidia Quadro 120M video card. The computer was purchased in late November of 2006 with XP Pro, and included a free upgrade to Vista Business. (Vista was available on MSDN but not yet via retail, so the Vista Business upgrades weren't shipped until March of '07.) Since we had an MSDN subscription at the time, I installed Vista Ultimate on it pretty much as soon as I got it. It ran happily until sometime in the spring of 2007 when Media Center (which I had never used except to watch DVDs) started throwing some kind of bizarre SQL (CE?) error. This error would pop up at random times just while using the computer. Furthermore, Media Center would no longer start. I never identified the cause of this error. I had the Vista Business upgrade by this time, so I nuked the machine, installed XP and all the drivers, and then the Vista Business upgrade. Again, it ran happily for a few months and then started behaving badly once again. Vista Business doesn't have Media Center, so this exhibited completely unrelated symptoms. For no apparent reason and at fairly random times, the machine would suddenly appear to freeze up or run very slowly. For example, launching a new application window (any app) might take 30-45 seconds to paint fully. However, Task Manager showed very low CPU load, memory, etc. I tried all the normal stuff (chkdsk, defrag, etc.) and ran several diagnostic programs to try to identify any problems, but none found anything. It eventually reached the point that the computer was all but unusable, so I nuked it again and installed XP. This time I decided to stick with XP instead of going to Vista. However, within the past couple of months it has started to exhibit the same symptoms in XP that I used to see in Vista. The computer is still under Dell warranty until December, but so far they aren't any help unless I can identify a specific problem. A friend (partner in a now-dead business) has an identical machine that was purchased at the same time. His machine exhibits none of these symptoms, which leads me to believe it is a hardware issue, but I can't figure out how to identify it. Any ideas? Utilities? Seen something similar? At this point I can't even identify any pattern to the behavior, but would be willing to run a "stress test"-style app for as long as a couple days if I had any hope that it would find something. EDIT July 17 I'm testing jerryjvl's answer regarding the video card, though I'm not sure it fully explains the symptoms yet. This morning I ran a video stress test. The test itself ran fine, but immediately afterward the PC started acting up again. I left ProcExp open and various system processes were consuming 50-60% of the CPU but with no apparent reason. For example, "services.exe" was eating about 40%, but the sum of its child processes wasn't higher than about 5%. I left it alone for several minutes to settle down, and then it was fine again. I used the "video card stability test" from firestone-group.com. Its output isn't very detailed, but it at least exercises the hardware pretty hard. EDIT July 22 Thanks for your excellent suggestions. Here is an update on what I have tried so far. Ran memtest86, SeaTools (Seagate), Hitachi drive fitness test, video card stability test (mentioned above). The video card test was the only one that seemed to produce any results, though it didn't occur during the actual test. I defragged the drive (again...) with JkDefrag I dropped the video card

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  • Multi-tenant ASP.NET MVC – Introduction

    - by zowens
    I’ve read a few different blogs that talk about multi-tenancy and how to resolve some of the issues surrounding multi-tenancy. What I’ve come to realize is that these implementations overcomplicate the issues and give only a muddy implementation! I’ve seen some really illogical code out there. I have recently been building a multi-tenancy framework for internal use at eagleenvision.net. Through this process, I’ve realized a few different techniques to make building multi-tenant applications actually quite easy. I will be posting a few different entries over the issue and my personal implementation. In this first post, I will discuss what multi-tenancy means and how my implementation will be structured.   So what’s the problem? Here’s the deal. Multi-tenancy is basically a technique of code-reuse of web application code. A multi-tenant application is an application that runs a single instance for multiple clients. Here the “client” is different URL bindings on IIS using ASP.NET MVC. The problem with different instances of the, essentially, same application is that you have to spin up different instances of ASP.NET. As the number of running instances of ASP.NET grows, so does the memory footprint of IIS. Stack Exchange shifted its architecture to multi-tenancy March. As the blog post explains, multi-tenancy saves cost in terms of memory utilization and physical disc storage. If you use the same code base for many applications, multi-tenancy just makes sense. You’ll reduce the amount of work it takes to synchronize the site implementations and you’ll thank your lucky stars later for choosing to use one application for multiple sites. Multi-tenancy allows the freedom of extensibility while relying on some pre-built code.   You’d think this would be simple. I have actually seen a real lack of reference material on the subject in terms of ASP.NET MVC. This is somewhat surprising given the number of users of ASP.NET MVC. However, I will certainly fill the void ;). Implementing a multi-tenant application takes a little thinking. It’s not straight-forward because the possibilities of implementation are endless. I have yet to see a great implementation of a multi-tenant MVC application. The only one that comes close to what I have in mind is Rob Ashton’s implementation (all the entries are listed on this page). There’s some really nasty code in there… something I’d really like to avoid. He has also written a library (MvcEx) that attempts to aid multi-tenant development. This code is even worse, in my honest opinion. Once I start seeing Reflection.Emit, I have to assume the worst :) In all seriousness, if his implementation makes sense to you, use it! It’s a fine implementation that should be given a look. At least look at the code. I will reference MvcEx going forward as a comparison to my implementation. I will explain why my approach differs from MvcEx and how it is better or worse (hopefully better).   Core Goals of my Multi-Tenant Implementation The first, and foremost, goal is to use Inversion of Control containers to my advantage. As you will see throughout this series, I pass around containers quite frequently and rely on their use heavily. I will be using StructureMap in my implementation. However, you could probably use your favorite IoC tool instead. <RANT> However, please don’t be stupid and abstract your IoC tool. Each IoC is powerful and by abstracting the capabilities, you’re doing yourself a real disservice. Who in the world swaps out IoC tools…? No one!</RANT> (It had to be said.) I will outline some of the goodness of StructureMap as we go along. This is really an invaluable tool in my tool belt and simple to use in my multi-tenant implementation. The second core goal is to represent a tenant as easily as possible. Just as a dependency container will be a first-class citizen, so will a tenant. This allows us to easily extend and use tenants. This will also allow different ways of “plugging in” tenants into your application. In my implementation, there will be a single dependency container for a single tenant. This will enable isolation of the dependencies of the tenant. The third goal is to use composition as a means to delegate “core” functions out to the tenant. More on this later.   Features In MvcExt, “Modules” are a code element of the infrastructure. I have simplified this concept and have named this “Features”. A feature is a simple element of an application. Controllers can be specified to have a feature and actions can have “sub features”. Each tenant can select features it needs and the other features will be hidden to the tenant’s users. My implementation doesn’t require something to be a feature. A controller can be common to all tenants. For example, (as you will see) I have a “Content” controller that will return the CSS, Javascript and Images for a tenant. This is common logic to all tenants and shouldn’t be hidden or considered a “feature”; Content is a core component.   Up next My next post will be all about the code. I will reveal some of the foundation to the way I do multi-tenancy. I will have posts dedicated to Foundation, Controllers, Views, Caching, Content and how to setup the tenants. Each post will be in-depth about the issues and implementation details, while adhering to my core goals outlined in this post. As always, comment with questions of DM me on twitter or send me an email.

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  • ASP.NET Web API Exception Handling

    - by Fredrik N
    When I talk about exceptions in my product team I often talk about two kind of exceptions, business and critical exceptions. Business exceptions are exceptions thrown based on “business rules”, for example if you aren’t allowed to do a purchase. Business exceptions in most case aren’t important to log into a log file, they can directly be shown to the user. An example of a business exception could be "DeniedToPurchaseException”, or some validation exceptions such as “FirstNameIsMissingException” etc. Critical Exceptions are all other kind of exceptions such as the SQL server is down etc. Those kind of exception message need to be logged and should not reach the user, because they can contain information that can be harmful if it reach out to wrong kind of users. I often distinguish business exceptions from critical exceptions by creating a base class called BusinessException, then in my error handling code I catch on the type BusinessException and all other exceptions will be handled as critical exceptions. This blog post will be about different ways to handle exceptions and how Business and Critical Exceptions could be handled. Web API and Exceptions the basics When an exception is thrown in a ApiController a response message will be returned with a status code set to 500 and a response formatted by the formatters based on the “Accept” or “Content-Type” HTTP header, for example JSON or XML. Here is an example:   public IEnumerable<string> Get() { throw new ApplicationException("Error!!!!!"); return new string[] { "value1", "value2" }; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The response message will be: HTTP/1.1 500 Internal Server Error Content-Length: 860 Content-Type: application/json; charset=utf-8 { "ExceptionType":"System.ApplicationException","Message":"Error!!!!!","StackTrace":" at ..."} .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The stack trace will be returned to the client, this is because of making it easier to debug. Be careful so you don’t leak out some sensitive information to the client. So as long as you are developing your API, this is not harmful. In a production environment it can be better to log exceptions and return a user friendly exception instead of the original exception. There is a specific exception shipped with ASP.NET Web API that will not use the formatters based on the “Accept” or “Content-Type” HTTP header, it is the exception is the HttpResponseException class. Here is an example where the HttpReponseExcetpion is used: // GET api/values [ExceptionHandling] public IEnumerable<string> Get() { throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError)); return new string[] { "value1", "value2" }; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The response will not contain any content, only header information and the status code based on the HttpStatusCode passed as an argument to the HttpResponseMessage. Because the HttpResponsException takes a HttpResponseMessage as an argument, we can give the response a content: public IEnumerable<string> Get() { throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent("My Error Message"), ReasonPhrase = "Critical Exception" }); return new string[] { "value1", "value2" }; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The code above will have the following response:   HTTP/1.1 500 Critical Exception Content-Length: 5 Content-Type: text/plain; charset=utf-8 My Error Message .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The Content property of the HttpResponseMessage doesn’t need to be just plain text, it can also be other formats, for example JSON, XML etc. By using the HttpResponseException we can for example catch an exception and throw a user friendly exception instead: public IEnumerable<string> Get() { try { DoSomething(); return new string[] { "value1", "value2" }; } catch (Exception e) { throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent("An error occurred, please try again or contact the administrator."), ReasonPhrase = "Critical Exception" }); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Adding a try catch to every ApiController methods will only end in duplication of code, by using a custom ExceptionFilterAttribute or our own custom ApiController base class we can reduce code duplicationof code and also have a more general exception handler for our ApiControllers . By creating a custom ApiController’s and override the ExecuteAsync method, we can add a try catch around the base.ExecuteAsync method, but I prefer to skip the creation of a own custom ApiController, better to use a solution that require few files to be modified. The ExceptionFilterAttribute has a OnException method that we can override and add our exception handling. Here is an example: using System; using System.Diagnostics; using System.Net; using System.Net.Http; using System.Web.Http; using System.Web.Http.Filters; public class ExceptionHandlingAttribute : ExceptionFilterAttribute { public override void OnException(HttpActionExecutedContext context) { if (context.Exception is BusinessException) { throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent(context.Exception.Message), ReasonPhrase = "Exception" }); } //Log Critical errors Debug.WriteLine(context.Exception); throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent("An error occurred, please try again or contact the administrator."), ReasonPhrase = "Critical Exception" }); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Note: Something to have in mind is that the ExceptionFilterAttribute will be ignored if the ApiController action method throws a HttpResponseException. The code above will always make sure a HttpResponseExceptions will be returned, it will also make sure the critical exceptions will show a more user friendly message. The OnException method can also be used to log exceptions. By using a ExceptionFilterAttribute the Get() method in the previous example can now look like this: public IEnumerable<string> Get() { DoSomething(); return new string[] { "value1", "value2" }; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } To use the an ExceptionFilterAttribute, we can for example add the ExceptionFilterAttribute to our ApiControllers methods or to the ApiController class definition, or register it globally for all ApiControllers. You can read more about is here. Note: If something goes wrong in the ExceptionFilterAttribute and an exception is thrown that is not of type HttpResponseException, a formatted exception will be thrown with stack trace etc to the client. How about using a custom IHttpActionInvoker? We can create our own IHTTPActionInvoker and add Exception handling to the invoker. The IHttpActionInvoker will be used to invoke the ApiController’s ExecuteAsync method. Here is an example where the default IHttpActionInvoker, ApiControllerActionInvoker, is used to add exception handling: public class MyApiControllerActionInvoker : ApiControllerActionInvoker { public override Task<HttpResponseMessage> InvokeActionAsync(HttpActionContext actionContext, System.Threading.CancellationToken cancellationToken) { var result = base.InvokeActionAsync(actionContext, cancellationToken); if (result.Exception != null && result.Exception.GetBaseException() != null) { var baseException = result.Exception.GetBaseException(); if (baseException is BusinessException) { return Task.Run<HttpResponseMessage>(() => new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent(baseException.Message), ReasonPhrase = "Error" }); } else { //Log critical error Debug.WriteLine(baseException); return Task.Run<HttpResponseMessage>(() => new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent(baseException.Message), ReasonPhrase = "Critical Error" }); } } return result; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } You can register the IHttpActionInvoker with your own IoC to resolve the MyApiContollerActionInvoker, or add it in the Global.asax: GlobalConfiguration.Configuration.Services.Remove(typeof(IHttpActionInvoker), GlobalConfiguration.Configuration.Services.GetActionInvoker()); GlobalConfiguration.Configuration.Services.Add(typeof(IHttpActionInvoker), new MyApiControllerActionInvoker()); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   How about using a Message Handler for Exception Handling? By creating a custom Message Handler, we can handle error after the ApiController and the ExceptionFilterAttribute is invoked and in that way create a global exception handler, BUT, the only thing we can take a look at is the HttpResponseMessage, we can’t add a try catch around the Message Handler’s SendAsync method. The last Message Handler that will be used in the Wep API pipe-line is the HttpControllerDispatcher and this Message Handler is added to the HttpServer in an early stage. The HttpControllerDispatcher will use the IHttpActionInvoker to invoke the ApiController method. The HttpControllerDipatcher has a try catch that will turn ALL exceptions into a HttpResponseMessage, so that is the reason why a try catch around the SendAsync in a custom Message Handler want help us. If we create our own Host for the Wep API we could create our own custom HttpControllerDispatcher and add or exception handler to that class, but that would be little tricky but is possible. We can in a Message Handler take a look at the HttpResponseMessage’s IsSuccessStatusCode property to see if the request has failed and if we throw the HttpResponseException in our ApiControllers, we could use the HttpResponseException and give it a Reason Phrase and use that to identify business exceptions or critical exceptions. I wouldn’t add an exception handler into a Message Handler, instead I should use the ExceptionFilterAttribute and register it globally for all ApiControllers. BUT, now to another interesting issue. What will happen if we have a Message Handler that throws an exception?  Those exceptions will not be catch and handled by the ExceptionFilterAttribute. I found a  bug in my previews blog post about “Log message Request and Response in ASP.NET WebAPI” in the MessageHandler I use to log incoming and outgoing messages. Here is the code from my blog before I fixed the bug:   public abstract class MessageHandler : DelegatingHandler { protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) { var corrId = string.Format("{0}{1}", DateTime.Now.Ticks, Thread.CurrentThread.ManagedThreadId); var requestInfo = string.Format("{0} {1}", request.Method, request.RequestUri); var requestMessage = await request.Content.ReadAsByteArrayAsync(); await IncommingMessageAsync(corrId, requestInfo, requestMessage); var response = await base.SendAsync(request, cancellationToken); var responseMessage = await response.Content.ReadAsByteArrayAsync(); await OutgoingMessageAsync(corrId, requestInfo, responseMessage); return response; } protected abstract Task IncommingMessageAsync(string correlationId, string requestInfo, byte[] message); protected abstract Task OutgoingMessageAsync(string correlationId, string requestInfo, byte[] message); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   If a ApiController throws a HttpResponseException, the Content property of the HttpResponseMessage from the SendAsync will be NULL. So a null reference exception is thrown within the MessageHandler. The yellow screen of death will be returned to the client, and the content is HTML and the Http status code is 500. The bug in the MessageHandler was solved by adding a check against the HttpResponseMessage’s IsSuccessStatusCode property: public abstract class MessageHandler : DelegatingHandler { protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) { var corrId = string.Format("{0}{1}", DateTime.Now.Ticks, Thread.CurrentThread.ManagedThreadId); var requestInfo = string.Format("{0} {1}", request.Method, request.RequestUri); var requestMessage = await request.Content.ReadAsByteArrayAsync(); await IncommingMessageAsync(corrId, requestInfo, requestMessage); var response = await base.SendAsync(request, cancellationToken); byte[] responseMessage; if (response.IsSuccessStatusCode) responseMessage = await response.Content.ReadAsByteArrayAsync(); else responseMessage = Encoding.UTF8.GetBytes(response.ReasonPhrase); await OutgoingMessageAsync(corrId, requestInfo, responseMessage); return response; } protected abstract Task IncommingMessageAsync(string correlationId, string requestInfo, byte[] message); protected abstract Task OutgoingMessageAsync(string correlationId, string requestInfo, byte[] message); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } If we don’t handle the exceptions that can occur in a custom Message Handler, we can have a hard time to find the problem causing the exception. The savior in this case is the Global.asax’s Application_Error: protected void Application_Error() { var exception = Server.GetLastError(); Debug.WriteLine(exception); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } I would recommend you to add the Application_Error to the Global.asax and log all exceptions to make sure all kind of exception is handled. Summary There are different ways we could add Exception Handling to the Wep API, we can use a custom ApiController, ExceptionFilterAttribute, IHttpActionInvoker or Message Handler. The ExceptionFilterAttribute would be a good place to add a global exception handling, require very few modification, just register it globally for all ApiControllers, even the IHttpActionInvoker can be used to minimize the modifications of files. Adding the Application_Error to the global.asax is a good way to catch all unhandled exception that can occur, for example exception thrown in a Message Handler.   If you want to know when I have posted a blog post, you can follow me on twitter @fredrikn

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  • An Introduction to ASP.NET Web API

    - by Rick Strahl
    Microsoft recently released ASP.NET MVC 4.0 and .NET 4.5 and along with it, the brand spanking new ASP.NET Web API. Web API is an exciting new addition to the ASP.NET stack that provides a new, well-designed HTTP framework for creating REST and AJAX APIs (API is Microsoft’s new jargon for a service, in case you’re wondering). Although Web API ships and installs with ASP.NET MVC 4, you can use Web API functionality in any ASP.NET project, including WebForms, WebPages and MVC or just a Web API by itself. And you can also self-host Web API in your own applications from Console, Desktop or Service applications. If you're interested in a high level overview on what ASP.NET Web API is and how it fits into the ASP.NET stack you can check out my previous post: Where does ASP.NET Web API fit? In the following article, I'll focus on a practical, by example introduction to ASP.NET Web API. All the code discussed in this article is available in GitHub: https://github.com/RickStrahl/AspNetWebApiArticle [republished from my Code Magazine Article and updated for RTM release of ASP.NET Web API] Getting Started To start I’ll create a new empty ASP.NET application to demonstrate that Web API can work with any kind of ASP.NET project. Although you can create a new project based on the ASP.NET MVC/Web API template to quickly get up and running, I’ll take you through the manual setup process, because one common use case is to add Web API functionality to an existing ASP.NET application. This process describes the steps needed to hook up Web API to any ASP.NET 4.0 application. Start by creating an ASP.NET Empty Project. Then create a new folder in the project called Controllers. Add a Web API Controller Class Once you have any kind of ASP.NET project open, you can add a Web API Controller class to it. Web API Controllers are very similar to MVC Controller classes, but they work in any kind of project. Add a new item to this folder by using the Add New Item option in Visual Studio and choose Web API Controller Class, as shown in Figure 1. Figure 1: This is how you create a new Controller Class in Visual Studio   Make sure that the name of the controller class includes Controller at the end of it, which is required in order for Web API routing to find it. Here, the name for the class is AlbumApiController. For this example, I’ll use a Music Album model to demonstrate basic behavior of Web API. The model consists of albums and related songs where an album has properties like Name, Artist and YearReleased and a list of songs with a SongName and SongLength as well as an AlbumId that links it to the album. You can find the code for the model (and the rest of these samples) on Github. To add the file manually, create a new folder called Model, and add a new class Album.cs and copy the code into it. There’s a static AlbumData class with a static CreateSampleAlbumData() method that creates a short list of albums on a static .Current that I’ll use for the examples. Before we look at what goes into the controller class though, let’s hook up routing so we can access this new controller. Hooking up Routing in Global.asax To start, I need to perform the one required configuration task in order for Web API to work: I need to configure routing to the controller. Like MVC, Web API uses routing to provide clean, extension-less URLs to controller methods. Using an extension method to ASP.NET’s static RouteTable class, you can use the MapHttpRoute() (in the System.Web.Http namespace) method to hook-up the routing during Application_Start in global.asax.cs shown in Listing 1.using System; using System.Web.Routing; using System.Web.Http; namespace AspNetWebApi { public class Global : System.Web.HttpApplication { protected void Application_Start(object sender, EventArgs e) { RouteTable.Routes.MapHttpRoute( name: "AlbumVerbs", routeTemplate: "albums/{title}", defaults: new { symbol = RouteParameter.Optional, controller="AlbumApi" } ); } } } This route configures Web API to direct URLs that start with an albums folder to the AlbumApiController class. Routing in ASP.NET is used to create extensionless URLs and allows you to map segments of the URL to specific Route Value parameters. A route parameter, with a name inside curly brackets like {name}, is mapped to parameters on the controller methods. Route parameters can be optional, and there are two special route parameters – controller and action – that determine the controller to call and the method to activate respectively. HTTP Verb Routing Routing in Web API can route requests by HTTP Verb in addition to standard {controller},{action} routing. For the first examples, I use HTTP Verb routing, as shown Listing 1. Notice that the route I’ve defined does not include an {action} route value or action value in the defaults. Rather, Web API can use the HTTP Verb in this route to determine the method to call the controller, and a GET request maps to any method that starts with Get. So methods called Get() or GetAlbums() are matched by a GET request and a POST request maps to a Post() or PostAlbum(). Web API matches a method by name and parameter signature to match a route, query string or POST values. In lieu of the method name, the [HttpGet,HttpPost,HttpPut,HttpDelete, etc] attributes can also be used to designate the accepted verbs explicitly if you don’t want to follow the verb naming conventions. Although HTTP Verb routing is a good practice for REST style resource APIs, it’s not required and you can still use more traditional routes with an explicit {action} route parameter. When {action} is supplied, the HTTP verb routing is ignored. I’ll talk more about alternate routes later. When you’re finished with initial creation of files, your project should look like Figure 2.   Figure 2: The initial project has the new API Controller Album model   Creating a small Album Model Now it’s time to create some controller methods to serve data. For these examples, I’ll use a very simple Album and Songs model to play with, as shown in Listing 2. public class Song { public string AlbumId { get; set; } [Required, StringLength(80)] public string SongName { get; set; } [StringLength(5)] public string SongLength { get; set; } } public class Album { public string Id { get; set; } [Required, StringLength(80)] public string AlbumName { get; set; } [StringLength(80)] public string Artist { get; set; } public int YearReleased { get; set; } public DateTime Entered { get; set; } [StringLength(150)] public string AlbumImageUrl { get; set; } [StringLength(200)] public string AmazonUrl { get; set; } public virtual List<Song> Songs { get; set; } public Album() { Songs = new List<Song>(); Entered = DateTime.Now; // Poor man's unique Id off GUID hash Id = Guid.NewGuid().GetHashCode().ToString("x"); } public void AddSong(string songName, string songLength = null) { this.Songs.Add(new Song() { AlbumId = this.Id, SongName = songName, SongLength = songLength }); } } Once the model has been created, I also added an AlbumData class that generates some static data in memory that is loaded onto a static .Current member. The signature of this class looks like this and that's what I'll access to retrieve the base data:public static class AlbumData { // sample data - static list public static List<Album> Current = CreateSampleAlbumData(); /// <summary> /// Create some sample data /// </summary> /// <returns></returns> public static List<Album> CreateSampleAlbumData() { … }} You can check out the full code for the data generation online. Creating an AlbumApiController Web API shares many concepts of ASP.NET MVC, and the implementation of your API logic is done by implementing a subclass of the System.Web.Http.ApiController class. Each public method in the implemented controller is a potential endpoint for the HTTP API, as long as a matching route can be found to invoke it. The class name you create should end in Controller, which is how Web API matches the controller route value to figure out which class to invoke. Inside the controller you can implement methods that take standard .NET input parameters and return .NET values as results. Web API’s binding tries to match POST data, route values, form values or query string values to your parameters. Because the controller is configured for HTTP Verb based routing (no {action} parameter in the route), any methods that start with Getxxxx() are called by an HTTP GET operation. You can have multiple methods that match each HTTP Verb as long as the parameter signatures are different and can be matched by Web API. In Listing 3, I create an AlbumApiController with two methods to retrieve a list of albums and a single album by its title .public class AlbumApiController : ApiController { public IEnumerable<Album> GetAlbums() { var albums = AlbumData.Current.OrderBy(alb => alb.Artist); return albums; } public Album GetAlbum(string title) { var album = AlbumData.Current .SingleOrDefault(alb => alb.AlbumName.Contains(title)); return album; }} To access the first two requests, you can use the following URLs in your browser: http://localhost/aspnetWebApi/albumshttp://localhost/aspnetWebApi/albums/Dirty%20Deeds Note that you’re not specifying the actions of GetAlbum or GetAlbums in these URLs. Instead Web API’s routing uses HTTP GET verb to route to these methods that start with Getxxx() with the first mapping to the parameterless GetAlbums() method and the latter to the GetAlbum(title) method that receives the title parameter mapped as optional in the route. Content Negotiation When you access any of the URLs above from a browser, you get either an XML or JSON result returned back. The album list result for Chrome 17 and Internet Explorer 9 is shown Figure 3. Figure 3: Web API responses can vary depending on the browser used, demonstrating Content Negotiation in action as these two browsers send different HTTP Accept headers.   Notice that the results are not the same: Chrome returns an XML response and IE9 returns a JSON response. Whoa, what’s going on here? Shouldn’t we see the same result in both browsers? Actually, no. Web API determines what type of content to return based on Accept headers. HTTP clients, like browsers, use Accept headers to specify what kind of content they’d like to see returned. Browsers generally ask for HTML first, followed by a few additional content types. Chrome (and most other major browsers) ask for: Accept: text/html, application/xhtml+xml,application/xml; q=0.9,*/*;q=0.8 IE9 asks for: Accept: text/html, application/xhtml+xml, */* Note that Chrome’s Accept header includes application/xml, which Web API finds in its list of supported media types and returns an XML response. IE9 does not include an Accept header type that works on Web API by default, and so it returns the default format, which is JSON. This is an important and very useful feature that was missing from any previous Microsoft REST tools: Web API automatically switches output formats based on HTTP Accept headers. Nowhere in the server code above do you have to explicitly specify the output format. Rather, Web API determines what format the client is requesting based on the Accept headers and automatically returns the result based on the available formatters. This means that a single method can handle both XML and JSON results.. Using this simple approach makes it very easy to create a single controller method that can return JSON, XML, ATOM or even OData feeds by providing the appropriate Accept header from the client. By default you don’t have to worry about the output format in your code. Note that you can still specify an explicit output format if you choose, either globally by overriding the installed formatters, or individually by returning a lower level HttpResponseMessage instance and setting the formatter explicitly. More on that in a minute. Along the same lines, any content sent to the server via POST/PUT is parsed by Web API based on the HTTP Content-type of the data sent. The same formats allowed for output are also allowed on input. Again, you don’t have to do anything in your code – Web API automatically performs the deserialization from the content. Accessing Web API JSON Data with jQuery A very common scenario for Web API endpoints is to retrieve data for AJAX calls from the Web browser. Because JSON is the default format for Web API, it’s easy to access data from the server using jQuery and its getJSON() method. This example receives the albums array from GetAlbums() and databinds it into the page using knockout.js.$.getJSON("albums/", function (albums) { // make knockout template visible $(".album").show(); // create view object and attach array var view = { albums: albums }; ko.applyBindings(view); }); Figure 4 shows this and the next example’s HTML output. You can check out the complete HTML and script code at http://goo.gl/Ix33C (.html) and http://goo.gl/tETlg (.js). Figu Figure 4: The Album Display sample uses JSON data loaded from Web API.   The result from the getJSON() call is a JavaScript object of the server result, which comes back as a JavaScript array. In the code, I use knockout.js to bind this array into the UI, which as you can see, requires very little code, instead using knockout’s data-bind attributes to bind server data to the UI. Of course, this is just one way to use the data – it’s entirely up to you to decide what to do with the data in your client code. Along the same lines, I can retrieve a single album to display when the user clicks on an album. The response returns the album information and a child array with all the songs. The code to do this is very similar to the last example where we pulled the albums array:$(".albumlink").live("click", function () { var id = $(this).data("id"); // title $.getJSON("albums/" + id, function (album) { ko.applyBindings(album, $("#divAlbumDialog")[0]); $("#divAlbumDialog").show(); }); }); Here the URL looks like this: /albums/Dirty%20Deeds, where the title is the ID captured from the clicked element’s data ID attribute. Explicitly Overriding Output Format When Web API automatically converts output using content negotiation, it does so by matching Accept header media types to the GlobalConfiguration.Configuration.Formatters and the SupportedMediaTypes of each individual formatter. You can add and remove formatters to globally affect what formats are available and it’s easy to create and plug in custom formatters.The example project includes a JSONP formatter that can be plugged in to provide JSONP support for requests that have a callback= querystring parameter. Adding, removing or replacing formatters is a global option you can use to manipulate content. It’s beyond the scope of this introduction to show how it works, but you can review the sample code or check out my blog entry on the subject (http://goo.gl/UAzaR). If automatic processing is not desirable in a particular Controller method, you can override the response output explicitly by returning an HttpResponseMessage instance. HttpResponseMessage is similar to ActionResult in ASP.NET MVC in that it’s a common way to return an abstract result message that contains content. HttpResponseMessage s parsed by the Web API framework using standard interfaces to retrieve the response data, status code, headers and so on[MS2] . Web API turns every response – including those Controller methods that return static results – into HttpResponseMessage instances. Explicitly returning an HttpResponseMessage instance gives you full control over the output and lets you mostly bypass WebAPI’s post-processing of the HTTP response on your behalf. HttpResponseMessage allows you to customize the response in great detail. Web API’s attention to detail in the HTTP spec really shows; many HTTP options are exposed as properties and enumerations with detailed IntelliSense comments. Even if you’re new to building REST-based interfaces, the API guides you in the right direction for returning valid responses and response codes. For example, assume that I always want to return JSON from the GetAlbums() controller method and ignore the default media type content negotiation. To do this, I can adjust the output format and headers as shown in Listing 4.public HttpResponseMessage GetAlbums() { var albums = AlbumData.Current.OrderBy(alb => alb.Artist); // Create a new HttpResponse with Json Formatter explicitly var resp = new HttpResponseMessage(HttpStatusCode.OK); resp.Content = new ObjectContent<IEnumerable<Album>>( albums, new JsonMediaTypeFormatter()); // Get Default Formatter based on Content Negotiation //var resp = Request.CreateResponse<IEnumerable<Album>>(HttpStatusCode.OK, albums); resp.Headers.ConnectionClose = true; resp.Headers.CacheControl = new CacheControlHeaderValue(); resp.Headers.CacheControl.Public = true; return resp; } This example returns the same IEnumerable<Album> value, but it wraps the response into an HttpResponseMessage so you can control the entire HTTP message result including the headers, formatter and status code. In Listing 4, I explicitly specify the formatter using the JsonMediaTypeFormatter to always force the content to JSON.  If you prefer to use the default content negotiation with HttpResponseMessage results, you can create the Response instance using the Request.CreateResponse method:var resp = Request.CreateResponse<IEnumerable<Album>>(HttpStatusCode.OK, albums); This provides you an HttpResponse object that's pre-configured with the default formatter based on Content Negotiation. Once you have an HttpResponse object you can easily control most HTTP aspects on this object. What's sweet here is that there are many more detailed properties on HttpResponse than the core ASP.NET Response object, with most options being explicitly configurable with enumerations that make it easy to pick the right headers and response codes from a list of valid codes. It makes HTTP features available much more discoverable even for non-hardcore REST/HTTP geeks. Non-Serialized Results The output returned doesn’t have to be a serialized value but can also be raw data, like strings, binary data or streams. You can use the HttpResponseMessage.Content object to set a number of common Content classes. Listing 5 shows how to return a binary image using the ByteArrayContent class from a Controller method. [HttpGet] public HttpResponseMessage AlbumArt(string title) { var album = AlbumData.Current.FirstOrDefault(abl => abl.AlbumName.StartsWith(title)); if (album == null) { var resp = Request.CreateResponse<ApiMessageError>( HttpStatusCode.NotFound, new ApiMessageError("Album not found")); return resp; } // kinda silly - we would normally serve this directly // but hey - it's a demo. var http = new WebClient(); var imageData = http.DownloadData(album.AlbumImageUrl); // create response and return var result = new HttpResponseMessage(HttpStatusCode.OK); result.Content = new ByteArrayContent(imageData); result.Content.Headers.ContentType = new MediaTypeHeaderValue("image/jpeg"); return result; } The image retrieval from Amazon is contrived, but it shows how to return binary data using ByteArrayContent. It also demonstrates that you can easily return multiple types of content from a single controller method, which is actually quite common. If an error occurs - such as a resource can’t be found or a validation error – you can return an error response to the client that’s very specific to the error. In GetAlbumArt(), if the album can’t be found, we want to return a 404 Not Found status (and realistically no error, as it’s an image). Note that if you are not using HTTP Verb-based routing or not accessing a method that starts with Get/Post etc., you have to specify one or more HTTP Verb attributes on the method explicitly. Here, I used the [HttpGet] attribute to serve the image. Another option to handle the error could be to return a fixed placeholder image if no album could be matched or the album doesn’t have an image. When returning an error code, you can also return a strongly typed response to the client. For example, you can set the 404 status code and also return a custom error object (ApiMessageError is a class I defined) like this:return Request.CreateResponse<ApiMessageError>( HttpStatusCode.NotFound, new ApiMessageError("Album not found") );   If the album can be found, the image will be returned. The image is downloaded into a byte[] array, and then assigned to the result’s Content property. I created a new ByteArrayContent instance and assigned the image’s bytes and the content type so that it displays properly in the browser. There are other content classes available: StringContent, StreamContent, ByteArrayContent, MultipartContent, and ObjectContent are at your disposal to return just about any kind of content. You can create your own Content classes if you frequently return custom types and handle the default formatter assignments that should be used to send the data out . Although HttpResponseMessage results require more code than returning a plain .NET value from a method, it allows much more control over the actual HTTP processing than automatic processing. It also makes it much easier to test your controller methods as you get a response object that you can check for specific status codes and output messages rather than just a result value. Routing Again Ok, let’s get back to the image example. Using the original routing we have setup using HTTP Verb routing there's no good way to serve the image. In order to return my album art image I’d like to use a URL like this: http://localhost/aspnetWebApi/albums/Dirty%20Deeds/image In order to create a URL like this, I have to create a new Controller because my earlier routes pointed to the AlbumApiController using HTTP Verb routing. HTTP Verb based routing is great for representing a single set of resources such as albums. You can map operations like add, delete, update and read easily using HTTP Verbs. But you cannot mix action based routing into a an HTTP Verb routing controller - you can only map HTTP Verbs and each method has to be unique based on parameter signature. You can't have multiple GET operations to methods with the same signature. So GetImage(string id) and GetAlbum(string title) are in conflict in an HTTP GET routing scenario. In fact, I was unable to make the above Image URL work with any combination of HTTP Verb plus Custom routing using the single Albums controller. There are number of ways around this, but all involve additional controllers.  Personally, I think it’s easier to use explicit Action routing and then add custom routes if you need to simplify your URLs further. So in order to accommodate some of the other examples, I created another controller – AlbumRpcApiController – to handle all requests that are explicitly routed via actions (/albums/rpc/AlbumArt) or are custom routed with explicit routes defined in the HttpConfiguration. I added the AlbumArt() method to this new AlbumRpcApiController class. For the image URL to work with the new AlbumRpcApiController, you need a custom route placed before the default route from Listing 1.RouteTable.Routes.MapHttpRoute( name: "AlbumRpcApiAction", routeTemplate: "albums/rpc/{action}/{title}", defaults: new { title = RouteParameter.Optional, controller = "AlbumRpcApi", action = "GetAblums" } ); Now I can use either of the following URLs to access the image: Custom route: (/albums/rpc/{title}/image)http://localhost/aspnetWebApi/albums/PowerAge/image Action route: (/albums/rpc/action/{title})http://localhost/aspnetWebAPI/albums/rpc/albumart/PowerAge Sending Data to the Server To send data to the server and add a new album, you can use an HTTP POST operation. Since I’m using HTTP Verb-based routing in the original AlbumApiController, I can implement a method called PostAlbum()to accept a new album from the client. Listing 6 shows the Web API code to add a new album.public HttpResponseMessage PostAlbum(Album album) { if (!this.ModelState.IsValid) { // my custom error class var error = new ApiMessageError() { message = "Model is invalid" }; // add errors into our client error model for client foreach (var prop in ModelState.Values) { var modelError = prop.Errors.FirstOrDefault(); if (!string.IsNullOrEmpty(modelError.ErrorMessage)) error.errors.Add(modelError.ErrorMessage); else error.errors.Add(modelError.Exception.Message); } return Request.CreateResponse<ApiMessageError>(HttpStatusCode.Conflict, error); } // update song id which isn't provided foreach (var song in album.Songs) song.AlbumId = album.Id; // see if album exists already var matchedAlbum = AlbumData.Current .SingleOrDefault(alb => alb.Id == album.Id || alb.AlbumName == album.AlbumName); if (matchedAlbum == null) AlbumData.Current.Add(album); else matchedAlbum = album; // return a string to show that the value got here var resp = Request.CreateResponse(HttpStatusCode.OK, string.Empty); resp.Content = new StringContent(album.AlbumName + " " + album.Entered.ToString(), Encoding.UTF8, "text/plain"); return resp; } The PostAlbum() method receives an album parameter, which is automatically deserialized from the POST buffer the client sent. The data passed from the client can be either XML or JSON. Web API automatically figures out what format it needs to deserialize based on the content type and binds the content to the album object. Web API uses model binding to bind the request content to the parameter(s) of controller methods. Like MVC you can check the model by looking at ModelState.IsValid. If it’s not valid, you can run through the ModelState.Values collection and check each binding for errors. Here I collect the error messages into a string array that gets passed back to the client via the result ApiErrorMessage object. When a binding error occurs, you’ll want to return an HTTP error response and it’s best to do that with an HttpResponseMessage result. In Listing 6, I used a custom error class that holds a message and an array of detailed error messages for each binding error. I used this object as the content to return to the client along with my Conflict HTTP Status Code response. If binding succeeds, the example returns a string with the name and date entered to demonstrate that you captured the data. Normally, a method like this should return a Boolean or no response at all (HttpStatusCode.NoConent). The sample uses a simple static list to hold albums, so once you’ve added the album using the Post operation, you can hit the /albums/ URL to see that the new album was added. The client jQuery code to call the POST operation from the client with jQuery is shown in Listing 7. var id = new Date().getTime().toString(); var album = { "Id": id, "AlbumName": "Power Age", "Artist": "AC/DC", "YearReleased": 1977, "Entered": "2002-03-11T18:24:43.5580794-10:00", "AlbumImageUrl": http://ecx.images-amazon.com/images/…, "AmazonUrl": http://www.amazon.com/…, "Songs": [ { "SongName": "Rock 'n Roll Damnation", "SongLength": 3.12}, { "SongName": "Downpayment Blues", "SongLength": 4.22 }, { "SongName": "Riff Raff", "SongLength": 2.42 } ] } $.ajax( { url: "albums/", type: "POST", contentType: "application/json", data: JSON.stringify(album), processData: false, beforeSend: function (xhr) { // not required since JSON is default output xhr.setRequestHeader("Accept", "application/json"); }, success: function (result) { // reload list of albums page.loadAlbums(); }, error: function (xhr, status, p3, p4) { var err = "Error"; if (xhr.responseText && xhr.responseText[0] == "{") err = JSON.parse(xhr.responseText).message; alert(err); } }); The code in Listing 7 creates an album object in JavaScript to match the structure of the .NET Album class. This object is passed to the $.ajax() function to send to the server as POST. The data is turned into JSON and the content type set to application/json so that the server knows what to convert when deserializing in the Album instance. The jQuery code hooks up success and failure events. Success returns the result data, which is a string that’s echoed back with an alert box. If an error occurs, jQuery returns the XHR instance and status code. You can check the XHR to see if a JSON object is embedded and if it is, you can extract it by de-serializing it and accessing the .message property. REST standards suggest that updates to existing resources should use PUT operations. REST standards aside, I’m not a big fan of separating out inserts and updates so I tend to have a single method that handles both. But if you want to follow REST suggestions, you can create a PUT method that handles updates by forwarding the PUT operation to the POST method:public HttpResponseMessage PutAlbum(Album album) { return PostAlbum(album); } To make the corresponding $.ajax() call, all you have to change from Listing 7 is the type: from POST to PUT. Model Binding with UrlEncoded POST Variables In the example in Listing 7 I used JSON objects to post a serialized object to a server method that accepted an strongly typed object with the same structure, which is a common way to send data to the server. However, Web API supports a number of different ways that data can be received by server methods. For example, another common way is to use plain UrlEncoded POST  values to send to the server. Web API supports Model Binding that works similar (but not the same) as MVC's model binding where POST variables are mapped to properties of object parameters of the target method. This is actually quite common for AJAX calls that want to avoid serialization and the potential requirement of a JSON parser on older browsers. For example, using jQUery you might use the $.post() method to send a new album to the server (albeit one without songs) using code like the following:$.post("albums/",{AlbumName: "Dirty Deeds", YearReleased: 1976 … },albumPostCallback); Although the code looks very similar to the client code we used before passing JSON, here the data passed is URL encoded values (AlbumName=Dirty+Deeds&YearReleased=1976 etc.). Web API then takes this POST data and maps each of the POST values to the properties of the Album object in the method's parameter. Although the client code is different the server can both handle the JSON object, or the UrlEncoded POST values. Dynamic Access to POST Data There are also a few options available to dynamically access POST data, if you know what type of data you're dealing with. If you have POST UrlEncoded values, you can dynamically using a FormsDataCollection:[HttpPost] public string PostAlbum(FormDataCollection form) { return string.Format("{0} - released {1}", form.Get("AlbumName"),form.Get("RearReleased")); } The FormDataCollection is a very simple object, that essentially provides the same functionality as Request.Form[] in ASP.NET. Request.Form[] still works if you're running hosted in an ASP.NET application. However as a general rule, while ASP.NET's functionality is always available when running Web API hosted inside of an  ASP.NET application, using the built in classes specific to Web API makes it possible to run Web API applications in a self hosted environment outside of ASP.NET. If your client is sending JSON to your server, and you don't want to map the JSON to a strongly typed object because you only want to retrieve a few simple values, you can also accept a JObject parameter in your API methods:[HttpPost] public string PostAlbum(JObject jsonData) { dynamic json = jsonData; JObject jalbum = json.Album; JObject juser = json.User; string token = json.UserToken; var album = jalbum.ToObject<Album>(); var user = juser.ToObject<User>(); return String.Format("{0} {1} {2}", album.AlbumName, user.Name, token); } There quite a few options available to you to receive data with Web API, which gives you more choices for the right tool for the job. Unfortunately one shortcoming of Web API is that POST data is always mapped to a single parameter. This means you can't pass multiple POST parameters to methods that receive POST data. It's possible to accept multiple parameters, but only one can map to the POST content - the others have to come from the query string or route values. I have a couple of Blog POSTs that explain what works and what doesn't here: Passing multiple POST parameters to Web API Controller Methods Mapping UrlEncoded POST Values in ASP.NET Web API   Handling Delete Operations Finally, to round out the server API code of the album example we've been discussin, here’s the DELETE verb controller method that allows removal of an album by its title:public HttpResponseMessage DeleteAlbum(string title) { var matchedAlbum = AlbumData.Current.Where(alb => alb.AlbumName == title) .SingleOrDefault(); if (matchedAlbum == null) return new HttpResponseMessage(HttpStatusCode.NotFound); AlbumData.Current.Remove(matchedAlbum); return new HttpResponseMessage(HttpStatusCode.NoContent); } To call this action method using jQuery, you can use:$(".removeimage").live("click", function () { var $el = $(this).parent(".album"); var txt = $el.find("a").text(); $.ajax({ url: "albums/" + encodeURIComponent(txt), type: "Delete", success: function (result) { $el.fadeOut().remove(); }, error: jqError }); }   Note the use of the DELETE verb in the $.ajax() call, which routes to DeleteAlbum on the server. DELETE is a non-content operation, so you supply a resource ID (the title) via route value or the querystring. Routing Conflicts In all requests with the exception of the AlbumArt image example shown so far, I used HTTP Verb routing that I set up in Listing 1. HTTP Verb Routing is a recommendation that is in line with typical REST access to HTTP resources. However, it takes quite a bit of effort to create REST-compliant API implementations based only on HTTP Verb routing only. You saw one example that didn’t really fit – the return of an image where I created a custom route albums/{title}/image that required creation of a second controller and a custom route to work. HTTP Verb routing to a controller does not mix with custom or action routing to the same controller because of the limited mapping of HTTP verbs imposed by HTTP Verb routing. To understand some of the problems with verb routing, let’s look at another example. Let’s say you create a GetSortableAlbums() method like this and add it to the original AlbumApiController accessed via HTTP Verb routing:[HttpGet] public IQueryable<Album> SortableAlbums() { var albums = AlbumData.Current; // generally should be done only on actual queryable results (EF etc.) // Done here because we're running with a static list but otherwise might be slow return albums.AsQueryable(); } If you compile this code and try to now access the /albums/ link, you get an error: Multiple Actions were found that match the request. HTTP Verb routing only allows access to one GET operation per parameter/route value match. If more than one method exists with the same parameter signature, it doesn’t work. As I mentioned earlier for the image display, the only solution to get this method to work is to throw it into another controller. Because I already set up the AlbumRpcApiController I can add the method there. First, I should rename the method to SortableAlbums() so I’m not using a Get prefix for the method. This also makes the action parameter look cleaner in the URL - it looks less like a method and more like a noun. I can then create a new route that handles direct-action mapping:RouteTable.Routes.MapHttpRoute( name: "AlbumRpcApiAction", routeTemplate: "albums/rpc/{action}/{title}", defaults: new { title = RouteParameter.Optional, controller = "AlbumRpcApi", action = "GetAblums" } ); As I am explicitly adding a route segment – rpc – into the route template, I can now reference explicit methods in the Web API controller using URLs like this: http://localhost/AspNetWebApi/rpc/SortableAlbums Error Handling I’ve already done some minimal error handling in the examples. For example in Listing 6, I detected some known-error scenarios like model validation failing or a resource not being found and returning an appropriate HttpResponseMessage result. But what happens if your code just blows up or causes an exception? If you have a controller method, like this:[HttpGet] public void ThrowException() { throw new UnauthorizedAccessException("Unauthorized Access Sucka"); } You can call it with this: http://localhost/AspNetWebApi/albums/rpc/ThrowException The default exception handling displays a 500-status response with the serialized exception on the local computer only. When you connect from a remote computer, Web API throws back a 500  HTTP Error with no data returned (IIS then adds its HTML error page). The behavior is configurable in the GlobalConfiguration:GlobalConfiguration .Configuration .IncludeErrorDetailPolicy = IncludeErrorDetailPolicy.Never; If you want more control over your error responses sent from code, you can throw explicit error responses yourself using HttpResponseException. When you throw an HttpResponseException the response parameter is used to generate the output for the Controller action. [HttpGet] public void ThrowError() { var resp = Request.CreateResponse<ApiMessageError>( HttpStatusCode.BadRequest, new ApiMessageError("Your code stinks!")); throw new HttpResponseException(resp); } Throwing an HttpResponseException stops the processing of the controller method and immediately returns the response you passed to the exception. Unlike other Exceptions fired inside of WebAPI, HttpResponseException bypasses the Exception Filters installed and instead just outputs the response you provide. In this case, the serialized ApiMessageError result string is returned in the default serialization format – XML or JSON. You can pass any content to HttpResponseMessage, which includes creating your own exception objects and consistently returning error messages to the client. Here’s a small helper method on the controller that you might use to send exception info back to the client consistently:private void ThrowSafeException(string message, HttpStatusCode statusCode = HttpStatusCode.BadRequest) { var errResponse = Request.CreateResponse<ApiMessageError>(statusCode, new ApiMessageError() { message = message }); throw new HttpResponseException(errResponse); } You can then use it to output any captured errors from code:[HttpGet] public void ThrowErrorSafe() { try { List<string> list = null; list.Add("Rick"); } catch (Exception ex) { ThrowSafeException(ex.Message); } }   Exception Filters Another more global solution is to create an Exception Filter. Filters in Web API provide the ability to pre- and post-process controller method operations. An exception filter looks at all exceptions fired and then optionally creates an HttpResponseMessage result. Listing 8 shows an example of a basic Exception filter implementation.public class UnhandledExceptionFilter : ExceptionFilterAttribute { public override void OnException(HttpActionExecutedContext context) { HttpStatusCode status = HttpStatusCode.InternalServerError; var exType = context.Exception.GetType(); if (exType == typeof(UnauthorizedAccessException)) status = HttpStatusCode.Unauthorized; else if (exType == typeof(ArgumentException)) status = HttpStatusCode.NotFound; var apiError = new ApiMessageError() { message = context.Exception.Message }; // create a new response and attach our ApiError object // which now gets returned on ANY exception result var errorResponse = context.Request.CreateResponse<ApiMessageError>(status, apiError); context.Response = errorResponse; base.OnException(context); } } Exception Filter Attributes can be assigned to an ApiController class like this:[UnhandledExceptionFilter] public class AlbumRpcApiController : ApiController or you can globally assign it to all controllers by adding it to the HTTP Configuration's Filters collection:GlobalConfiguration.Configuration.Filters.Add(new UnhandledExceptionFilter()); The latter is a great way to get global error trapping so that all errors (short of hard IIS errors and explicit HttpResponseException errors) return a valid error response that includes error information in the form of a known-error object. Using a filter like this allows you to throw an exception as you normally would and have your filter create a response in the appropriate output format that the client expects. For example, an AJAX application can on failure expect to see a JSON error result that corresponds to the real error that occurred rather than a 500 error along with HTML error page that IIS throws up. You can even create some custom exceptions so you can differentiate your own exceptions from unhandled system exceptions - you often don't want to display error information from 'unknown' exceptions as they may contain sensitive system information or info that's not generally useful to users of your application/site. This is just one example of how ASP.NET Web API is configurable and extensible. Exception filters are just one example of how you can plug-in into the Web API request flow to modify output. Many more hooks exist and I’ll take a closer look at extensibility in Part 2 of this article in the future. Summary Web API is a big improvement over previous Microsoft REST and AJAX toolkits. The key features to its usefulness are its ease of use with simple controller based logic, familiar MVC-style routing, low configuration impact, extensibility at all levels and tight attention to exposing and making HTTP semantics easily discoverable and easy to use. Although none of the concepts used in Web API are new or radical, Web API combines the best of previous platforms into a single framework that’s highly functional, easy to work with, and extensible to boot. I think that Microsoft has hit a home run with Web API. Related Resources Where does ASP.NET Web API fit? Sample Source Code on GitHub Passing multiple POST parameters to Web API Controller Methods Mapping UrlEncoded POST Values in ASP.NET Web API Creating a JSONP Formatter for ASP.NET Web API Removing the XML Formatter from ASP.NET Web API Applications© Rick Strahl, West Wind Technologies, 2005-2012Posted in Web Api   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Where does ASP.NET Web API Fit?

    - by Rick Strahl
    With the pending release of ASP.NET MVC 4 and the new ASP.NET Web API, there has been a lot of discussion of where the new Web API technology fits in the ASP.NET Web stack. There are a lot of choices to build HTTP based applications available now on the stack - we've come a long way from when WebForms and Http Handlers/Modules where the only real options. Today we have WebForms, MVC, ASP.NET Web Pages, ASP.NET AJAX, WCF REST and now Web API as well as the core ASP.NET runtime to choose to build HTTP content with. Web API definitely squarely addresses the 'API' aspect - building consumable services - rather than HTML content, but even to that end there are a lot of choices you have today. So where does Web API fit, and when doesn't it? But before we get into that discussion, let's talk about what a Web API is and why we should care. What's a Web API? HTTP 'APIs' (Microsoft's new terminology for a service I guess)  are becoming increasingly more important with the rise of the many devices in use today. Most mobile devices like phones and tablets run Apps that are using data retrieved from the Web over HTTP. Desktop applications are also moving in this direction with more and more online content and synching moving into even traditional desktop applications. The pending Windows 8 release promises an app like platform for both the desktop and other devices, that also emphasizes consuming data from the Cloud. Likewise many Web browser hosted applications these days are relying on rich client functionality to create and manipulate the browser user interface, using AJAX rather than server generated HTML data to load up the user interface with data. These mobile or rich Web applications use their HTTP connection to return data rather than HTML markup in the form of JSON or XML typically. But an API can also serve other kinds of data, like images or other binary files, or even text data and HTML (although that's less common). A Web API is what feeds rich applications with data. ASP.NET Web API aims to service this particular segment of Web development by providing easy semantics to route and handle incoming requests and an easy to use platform to serve HTTP data in just about any content format you choose to create and serve from the server. But .NET already has various HTTP Platforms The .NET stack already includes a number of technologies that provide the ability to create HTTP service back ends, and it has done so since the very beginnings of the .NET platform. From raw HTTP Handlers and Modules in the core ASP.NET runtime, to high level platforms like ASP.NET MVC, Web Forms, ASP.NET AJAX and the WCF REST engine (which technically is not ASP.NET, but can integrate with it), you've always been able to handle just about any kind of HTTP request and response with ASP.NET. The beauty of the raw ASP.NET platform is that it provides you everything you need to build just about any type of HTTP application you can dream up from low level APIs/custom engines to high level HTML generation engine. ASP.NET as a core platform clearly has stood the test of time 10+ years later and all other frameworks like Web API are built on top of this ASP.NET core. However, although it's possible to create Web APIs / Services using any of the existing out of box .NET technologies, none of them have been a really nice fit for building arbitrary HTTP based APIs. Sure, you can use an HttpHandler to create just about anything, but you have to build a lot of plumbing to build something more complex like a comprehensive API that serves a variety of requests, handles multiple output formats and can easily pass data up to the server in a variety of ways. Likewise you can use ASP.NET MVC to handle routing and creating content in various formats fairly easily, but it doesn't provide a great way to automatically negotiate content types and serve various content formats directly (it's possible to do with some plumbing code of your own but not built in). Prior to Web API, Microsoft's main push for HTTP services has been WCF REST, which was always an awkward technology that had a severe personality conflict, not being clear on whether it wanted to be part of WCF or purely a separate technology. In the end it didn't do either WCF compatibility or WCF agnostic pure HTTP operation very well, which made for a very developer-unfriendly environment. Personally I didn't like any of the implementations at the time, so much so that I ended up building my own HTTP service engine (as part of the West Wind Web Toolkit), as have a few other third party tools that provided much better integration and ease of use. With the release of Web API for the first time I feel that I can finally use the tools in the box and not have to worry about creating and maintaining my own toolkit as Web API addresses just about all the features I implemented on my own and much more. ASP.NET Web API provides a better HTTP Experience ASP.NET Web API differentiates itself from the previous Microsoft in-box HTTP service solutions in that it was built from the ground up around the HTTP protocol and its messaging semantics. Unlike WCF REST or ASP.NET AJAX with ASMX, it’s a brand new platform rather than bolted on technology that is supposed to work in the context of an existing framework. The strength of the new ASP.NET Web API is that it combines the best features of the platforms that came before it, to provide a comprehensive and very usable HTTP platform. Because it's based on ASP.NET and borrows a lot of concepts from ASP.NET MVC, Web API should be immediately familiar and comfortable to most ASP.NET developers. Here are some of the features that Web API provides that I like: Strong Support for URL Routing to produce clean URLs using familiar MVC style routing semantics Content Negotiation based on Accept headers for request and response serialization Support for a host of supported output formats including JSON, XML, ATOM Strong default support for REST semantics but they are optional Easily extensible Formatter support to add new input/output types Deep support for more advanced HTTP features via HttpResponseMessage and HttpRequestMessage classes and strongly typed Enums to describe many HTTP operations Convention based design that drives you into doing the right thing for HTTP Services Very extensible, based on MVC like extensibility model of Formatters and Filters Self-hostable in non-Web applications  Testable using testing concepts similar to MVC Web API is meant to handle any kind of HTTP input and produce output and status codes using the full spectrum of HTTP functionality available in a straight forward and flexible manner. Looking at the list above you can see that a lot of functionality is very similar to ASP.NET MVC, so many ASP.NET developers should feel quite comfortable with the concepts of Web API. The Routing and core infrastructure of Web API are very similar to how MVC works providing many of the benefits of MVC, but with focus on HTTP access and manipulation in Controller methods rather than HTML generation in MVC. There’s much improved support for content negotiation based on HTTP Accept headers with the framework capable of detecting automatically what content the client is sending and requesting and serving the appropriate data format in return. This seems like such a little and obvious thing, but it's really important. Today's service backends often are used by multiple clients/applications and being able to choose the right data format for what fits best for the client is very important. While previous solutions were able to accomplish this using a variety of mixed features of WCF and ASP.NET, Web API combines all this functionality into a single robust server side HTTP framework that intrinsically understands the HTTP semantics and subtly drives you in the right direction for most operations. And when you need to customize or do something that is not built in, there are lots of hooks and overrides for most behaviors, and even many low level hook points that allow you to plug in custom functionality with relatively little effort. No Brainers for Web API There are a few scenarios that are a slam dunk for Web API. If your primary focus of an application or even a part of an application is some sort of API then Web API makes great sense. HTTP ServicesIf you're building a comprehensive HTTP API that is to be consumed over the Web, Web API is a perfect fit. You can isolate the logic in Web API and build your application as a service breaking out the logic into controllers as needed. Because the primary interface is the service there's no confusion of what should go where (MVC or API). Perfect fit. Primary AJAX BackendsIf you're building rich client Web applications that are relying heavily on AJAX callbacks to serve its data, Web API is also a slam dunk. Again because much if not most of the business logic will probably end up in your Web API service logic, there's no confusion over where logic should go and there's no duplication. In Single Page Applications (SPA), typically there's very little HTML based logic served other than bringing up a shell UI and then filling the data from the server with AJAX which means the business logic required for data retrieval and data acceptance and validation too lives in the Web API. Perfect fit. Generic HTTP EndpointsAnother good fit are generic HTTP endpoints that to serve data or handle 'utility' type functionality in typical Web applications. If you need to implement an image server, or an upload handler in the past I'd implement that as an HTTP handler. With Web API you now have a well defined place where you can implement these types of generic 'services' in a location that can easily add endpoints (via Controller methods) or separated out as more full featured APIs. Granted this could be done with MVC as well, but Web API seems a clearer and more well defined place to store generic application services. This is one thing I used to do a lot of in my own libraries and Web API addresses this nicely. Great fit. Mixed HTML and AJAX Applications: Not a clear Choice  For all the commonality that Web API and MVC share they are fundamentally different platforms that are independent of each other. A lot of people have asked when does it make sense to use MVC vs. Web API when you're dealing with typical Web application that creates HTML and also uses AJAX functionality for rich functionality. While it's easy to say that all 'service'/AJAX logic should go into a Web API and all HTML related generation into MVC, that can often result in a lot of code duplication. Also MVC supports JSON and XML result data fairly easily as well so there's some confusion where that 'trigger point' is of when you should switch to Web API vs. just implementing functionality as part of MVC controllers. Ultimately there's a tradeoff between isolation of functionality and duplication. A good rule of thumb I think works is that if a large chunk of the application's functionality serves data Web API is a good choice, but if you have a couple of small AJAX requests to serve data to a grid or autocomplete box it'd be overkill to separate out that logic into a separate Web API controller. Web API does add overhead to your application (it's yet another framework that sits on top of core ASP.NET) so it should be worth it .Keep in mind that MVC can generate HTML and JSON/XML and just about any other content easily and that functionality is not going away, so just because you Web API is there it doesn't mean you have to use it. Web API is not a full replacement for MVC obviously either since there's not the same level of support to feed HTML from Web API controllers (although you can host a RazorEngine easily enough if you really want to go that route) so if you're HTML is part of your API or application in general MVC is still a better choice either alone or in combination with Web API. I suspect (and hope) that in the future Web API's functionality will merge even closer with MVC so that you might even be able to mix functionality of both into single Controllers so that you don't have to make any trade offs, but at the moment that's not the case. Some Issues To think about Web API is similar to MVC but not the Same Although Web API looks a lot like MVC it's not the same and some common functionality of MVC behaves differently in Web API. For example, the way single POST variables are handled is different than MVC and doesn't lend itself particularly well to some AJAX scenarios with POST data. Code Duplication I already touched on this in the Mixed HTML and Web API section, but if you build an MVC application that also exposes a Web API it's quite likely that you end up duplicating a bunch of code and - potentially - infrastructure. You may have to create authentication logic both for an HTML application and for the Web API which might need something different altogether. More often than not though the same logic is used, and there's no easy way to share. If you implement an MVC ActionFilter and you want that same functionality in your Web API you'll end up creating the filter twice. AJAX Data or AJAX HTML On a recent post's comments, David made some really good points regarding the commonality of MVC and Web API's and its place. One comment that caught my eye was a little more generic, regarding data services vs. HTML services. David says: I see a lot of merit in the combination of Knockout.js, client side templates and view models, calling Web API for a responsive UI, but sometimes late at night that still leaves me wondering why I would no longer be using some of the nice tooling and features that have evolved in MVC ;-) You know what - I can totally relate to that. On the last Web based mobile app I worked on, we decided to serve HTML partials to the client via AJAX for many (but not all!) things, rather than sending down raw data to inject into the DOM on the client via templating or direct manipulation. While there are definitely more bytes on the wire, with this, the overhead ended up being actually fairly small if you keep the 'data' requests small and atomic. Performance was often made up by the lack of client side rendering of HTML. Server rendered HTML for AJAX templating gives so much better infrastructure support without having to screw around with 20 mismatched client libraries. Especially with MVC and partials it's pretty easy to break out your HTML logic into very small, atomic chunks, so it's actually easy to create small rendering islands that can be used via composition on the server, or via AJAX calls to small, tight partials that return HTML to the client. Although this is often frowned upon as to 'heavy', it worked really well in terms of developer effort as well as providing surprisingly good performance on devices. There's still plenty of jQuery and AJAX logic happening on the client but it's more manageable in small doses rather than trying to do the entire UI composition with JavaScript and/or 'not-quite-there-yet' template engines that are very difficult to debug. This is not an issue directly related to Web API of course, but something to think about especially for AJAX or SPA style applications. Summary Web API is a great new addition to the ASP.NET platform and it addresses a serious need for consolidation of a lot of half-baked HTTP service API technologies that came before it. Web API feels 'right', and hits the right combination of usability and flexibility at least for me and it's a good fit for true API scenarios. However, just because a new platform is available it doesn't meant that other tools or tech that came before it should be discarded or even upgraded to the new platform. There's nothing wrong with continuing to use MVC controller methods to handle API tasks if that's what your app is running now - there's very little to be gained by upgrading to Web API just because. But going forward Web API clearly is the way to go, when building HTTP data interfaces and it's good to see that Microsoft got this one right - it was sorely needed! Resources ASP.NET Web API AspConf Ask the Experts Session (first 5 minutes) © Rick Strahl, West Wind Technologies, 2005-2012Posted in Web Api   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Silverlight 4 Tools for VS 2010 and WCF RIA Services Released

    - by ScottGu
    The final release of the Silverlight 4 Tools for Visual Studio 2010 and WCF RIA Services is now available for download.  Download and Install If you already have Visual Studio 2010 installed (or the free Visual Web Developer 2010 Express), then you can install both the Silverlight 4 Tooling Support as well as WCF RIA Services support by downloading and running this setup package (note: please make sure to uninstall the preview release of the Silverlight 4 Tools for VS 2010 if you have previously installed that).  The Silverlight 4 Tools for VS 2010 package extends the Silverlight support built into Visual Studio 2010 and enables support for Silverlight 4 applications as well.  It also installs WCF RIA Services application templates and libraries: Today’s release includes the English edition of the Silverlight 4 Tooling – localized versions will be available next month for other Visual Studio languages as well. Silverlight Tooling Support Visual Studio 2010 includes rich tooling support for building Silverlight and WPF applications. It includes a WYSIWYG designer surface that enables you to easily use controls to construct UI – including the ability to take advantage of layout containers, and apply styles and resources: The VS 2010 designer enables you to leverage the rich data binding support within Silverlight and WPF, and easily wire-up bindings on controls.  The Data Sources window within Silverlight projects can be used to reference POCO objects (plain old CLR objects), WCF Services, WCF RIA Services client proxies or SharePoint Lists.  For example, let’s assume we add a “Person” class like below to our project: We could then add it to the Data Source window which will cause it to show up like below in the IDE: We can optionally customize the default UI control types that are associated for each property on the object.  For example, below we’ll default the BirthDate property to be represented by a “DatePicker” control: And then when we drag/drop the Person type from the Data Sources onto the design-surface it will automatically create UI controls that are bound to the properties of our Person class: VS 2010 allows you to optionally customize each UI binding further by selecting a control, and then right-click on any of its properties within the property-grid and pull up the “Apply Bindings” dialog: This will bring up a floating data-binding dialog that enables you to easily configure things like the binding path on the data source object, specify a format convertor, specify string-format settings, specify how validation errors should be handled, etc: In addition to providing WYSIWYG designer support for WPF and Silverlight applications, VS 2010 also provides rich XAML intellisense and code editing support – enabling a rich source editing environment. Silverlight 4 Tool Enhancements Today’s Silverlight 4 Tooling Release for VS 2010 includes a bunch of nice new features.  These include: Support for Silverlight Out of Browser Applications and Elevated Trust Applications You can open up a Silverlight application’s project properties window and click the “Enable Running Application Out of Browser” checkbox to enable you to install an offline, out of browser, version of your Silverlight 4 application.  You can then customize a number of “out of browser” settings of your application within Visual Studio: Notice above how you can now indicate that you want to run with elevated trust, with hardware graphics acceleration, as well as customize things like the Window style of the application (allowing you to build a nice polished window style for consumer applications). Support for Implicit Styles and “Go to Value Definition” Support: Silverlight 4 now allows you to define “implicit styles” for your applications.  This allows you to style controls by type (for example: have a default look for all buttons) and avoid you having to explicitly reference styles from each control.  In addition to honoring implicit styles on the designer-surface, VS 2010 also now allows you to right click on any control (or on one of it properties) and choose the “Go to Value Definition…” context menu to jump to the XAML where the style is defined, and from there you can easily navigate onward to any referenced resources.  This makes it much easier to figure out questions like “why is my button red?”: Style Intellisense VS 2010 enables you to easily modify styles you already have in XAML, and now you get intellisense for properties and their values within a style based on the TargetType of the specified control.  For example, below we have a style being set for controls of type “Button” (this is indicated by the “TargetType” property).  Notice how intellisense now automatically shows us properties for the Button control (even within the <Setter> element): Great Video - Watch the Silverlight Designer Features in Action You can see all of the above Silverlight 4 Tools for Visual Studio 2010 features (and some more cool ones I haven’t mentioned) demonstrated in action within this 20 minute Silverlight.TV video on Channel 9: WCF RIA Services Today we also shipped the V1 release of WCF RIA Services.  It is included and automatically installed as part of the Silverlight 4 Tools for Visual Studio 2010 setup. WCF RIA Services makes it much easier to build business applications with Silverlight.  It simplifies the traditional n-tier application pattern by bringing together the ASP.NET and Silverlight platforms using the power of WCF for communication.  WCF RIA Services provides a pattern to write application logic that runs on the mid-tier and controls access to data for queries, changes and custom operations. It also provides end-to-end support for common tasks such as data validation, authentication and authorization based on roles by integrating with Silverlight components on the client and ASP.NET on the mid-tier. Put simply – it makes it much easier to query data stored on a server from a client machine, optionally manipulate/modify the data on the client, and then save it back to the server.  It supports a validation architecture that helps ensure that your data is kept secure and business rules are applied consistently on both the client and middle-tiers. WCF RIA Services uses WCF for communication between the client and the server  It supports both an optimized .NET to .NET binary serialization format, as well as a set of open extensions to the ATOM format known as ODATA and an optional JavaScript Object Notation (JSON) format that can be used by any client. You can hear Nikhil and Dinesh talk a little about WCF RIA Services in this 13 minutes Channel 9 video. Putting it all Together – the Silverlight 4 Training Kit Check out the Silverlight 4 Training Kit to learn more about how to build business applications with Silverlight 4, Visual Studio 2010 and WCF RIA Services. The training kit includes 8 modules, 25 videos, and several hands-on labs that explain Silverlight 4 and WCF RIA Services concepts and walks you through building an end-to-end application with them.    The training kit is available for free and is a great way to get started. Summary I’m really excited about today’s release – as they really complete the Silverlight development story and deliver a great end to end runtime + tooling story for building applications.  All of the above features are available for use both in VS 2010 as well as the free Visual Web Developer 2010 Express Edition – making it really easy to get started building great solutions. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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