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• Expert iptables help needed?

  - by Asad Moeen

  After a detailed analysis, I collected these details. I am under a UDP Flood which is more of application dependent. I run a Game-Server and an attacker is flooding me with "getstatus" query which makes the GameServer respond by making the replies to the query which cause output to the attacker's IP as high as 30mb/s and server lag. Here are the packet details, Packet starts with 4 bytes 0xff and then getstatus. Theoretically, the packet is like "\xff\xff\xff\xffgetstatus " Now that I've tried a lot of iptables variations like state and rate-limiting along side but those didn't work. Rate Limit works good but only when the Server is not started. As soon as the server starts, no iptables rule seems to block it. Anyone else got more solutions? someone asked me to contact the provider and get it done at the Network/Router but that looks very odd and I believe they might not do it since that would also affect other clients. Responding to all those answers, I'd say: Firstly, its a VPS so they can't do it for me. Secondly, I don't care if something is coming in but since its application generated so there has to be a OS level solution to block the outgoing packets. At least the outgoing ones must be stopped. Secondly, its not Ddos since just 400kb/s input generates 30mb/s output from my GameServer. That never happens in a D-dos. Asking the provider/hardware level solution should be used in that case but this one is different. And Yes, Banning his IP stops the flood of outgoing packets but he has many more IP-Addresses as he spoofs his original so I just need something to block him automatically. Even tried a lot of Firewalls but as you know they are just front-ends to iptables so if something doesn't work on iptables, what would the firewalls do? These were the rules I tried, iptables -A INPUT -p udp -m state --state NEW -m recent --set --name DDOS --rsource iptables -A INPUT -p udp -m state --state NEW -m recent --update --seconds 1 --hitcount 5 --name DDOS --rsource -j DROP It works for the attacks on un-used ports but when the server is listening and responding to the incoming queries by the attacker, it never works. Okay Tom.H, your rules were working when I modified them somehow like this: iptables -A INPUT -p udp -m length --length 1:1024 -m recent --set --name XXXX --rsource iptables -A INPUT -p udp -m string --string "xxxxxxxxxx" --algo bm --to 65535 -m recent --update --seconds 1 --hitcount 15 --name XXXX --rsource -j DROP They worked for about 3 days very good where the string "xxxxxxxxx" would be rate-limited, blocked if someone flooded and also didn't affect the clients. But just today, I tried updating the chain to try to remove a previously blocked IP so for that I had to flush the chain and restore this rule ( iptables -X and iptables -F ), some clients were already connected to servers including me. So restoring the rules now would also block some of the clients string completely while some are not affected. So does this mean I need to restart the server or why else would this happen because the last time the rules were working, there was no one connected?

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• Attachments in Oracle BPM 11g – Create a BPM Process Instance by passing an Attachment

  - by Venugopal Mangipudi

  Problem Statement: On a recent engagement I had  a requirement where we needed to create BPM instances using a message start event. The challenge was that the instance needed to be created after polling a file location and attaching the picked up file (pdf) as an attachment to the instance. Proposed Solution: I was contemplating using process API to accomplish this,but came up with a solution which involves a BPEL process to pickup the file and send a notification to the BPM process by passing the attachment as a payload. The following are some of the brief steps that were used to build the solution: BPM Process to receive an attachment as part of the payload: The BPM Process is a very simple process which has a Message Start event that accepts the attachment as an argument and a Simple User Task that the user can use to view the attachment (as part of the OOTB attachment panel). The Input payload is based on AttachmentPayload.xsd.  The 3 key elements of the the payload are: <xsd:element name="filename" type="xsd:string"/> <xsd:element name="mimetype" type="xsd:string"/> <xsd:element name="content" type="xsd:base64Binary"/> A screenshot of the Human task data assignment that need to performed to attach the file is provided here. Once the process and the UI project (default generated UI) are deployed to the SOA server, copy the wsdl location of the process service (from EM). This WSDL would be used in the BPEL project to create the Instances in the BPM process after a file is polled. BPEL Process to Poll for File and create instances in the BPM process: For the BPEL process a File adapter was configured as a Read service (File Streaming option and keeping the Schema as Opaque). Once a location and the file pattern to poll are provided the Readservice Partner Link was wired to Invoke the BPEL Process. Also, using the BPM Process WSDL, we can create the Webservice reference and can invoke the start operation. Before we do the assignment for the Invoke operation, a global variable should be created to hold the value of the fileName of the file. The mapping to the global variable can be done on the Receive activity properties (jca.file.FileName).  So for the assign operation before we invoke the BPM process service, we can get the content of the file from the receive input variable and the fileName from the jca.file.FileName property. The mimetype needs to be hard coded to the mime-type of the file: application/pdf (I am still researching ways to derive the mime type as it is not available as part of the jca.file properties).  The screenshot of the BPEL process can be found here and the Assign activity can be found here. The project source can be found at the following location. A sample pdf file to test the project and a screenshot of the BPM Human task screen after the successful creation of the instance can be found here. References: [1] https://blogs.oracle.com/fmwinaction/entry/oracle_bpm_adding_an_attachment

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• Some non-generic collections

  - by Simon Cooper

  Although the collections classes introduced in .NET 2, 3.5 and 4 cover most scenarios, there are still some .NET 1 collections that don't have generic counterparts. In this post, I'll be examining what they do, why you might use them, and some things you'll need to bear in mind when doing so. BitArray System.Collections.BitArray is conceptually the same as a List<bool>, but whereas List<bool> stores each boolean in a single byte (as that's what the backing bool[] does), BitArray uses a single bit to store each value, and uses various bitmasks to access each bit individually. This means that BitArray is eight times smaller than a List<bool>. Furthermore, BitArray has some useful functions for bitmasks, like And, Xor and Not, and it's not limited to 32 or 64 bits; a BitArray can hold as many bits as you need. However, it's not all roses and kittens. There are some fundamental limitations you have to bear in mind when using BitArray: It's a non-generic collection. The enumerator returns object (a boxed boolean), rather than an unboxed bool. This means that if you do this: foreach (bool b in bitArray) { ... } Every single boolean value will be boxed, then unboxed. And if you do this: foreach (var b in bitArray) { ... } you'll have to manually unbox b on every iteration, as it'll come out of the enumerator an object. Instead, you should manually iterate over the collection using a for loop: for (int i=0; i<bitArray.Length; i++) { bool b = bitArray[i]; ... } Following on from that, if you want to use BitArray in the context of an IEnumerable<bool>, ICollection<bool> or IList<bool>, you'll need to write a wrapper class, or use the Enumerable.Cast<bool> extension method (although Cast would box and unbox every value you get out of it). There is no Add or Remove method. You specify the number of bits you need in the constructor, and that's what you get. You can change the length yourself using the Length property setter though. It doesn't implement IList. Although not really important if you're writing a generic wrapper around it, it is something to bear in mind if you're using it with pre-generic code. However, if you use BitArray carefully, it can provide significant gains over a List<bool> for functionality and efficiency of space. OrderedDictionary System.Collections.Specialized.OrderedDictionary does exactly what you would expect - it's an IDictionary that maintains items in the order they are added. It does this by storing key/value pairs in a Hashtable (to get O(1) key lookup) and an ArrayList (to maintain the order). You can access values by key or index, and insert or remove items at a particular index. The enumerator returns items in index order. However, the Keys and Values properties return ICollection, not IList, as you might expect; CopyTo doesn't maintain the same ordering, as it copies from the backing Hashtable, not ArrayList; and any operations that insert or remove items from the middle of the collection are O(n), just like a normal list. In short; don't use this class. If you need some sort of ordered dictionary, it would be better to write your own generic dictionary combining a Dictionary<TKey, TValue> and List<KeyValuePair<TKey, TValue>> or List<TKey> for your specific situation. ListDictionary and HybridDictionary To look at why you might want to use ListDictionary or HybridDictionary, we need to examine the performance of these dictionaries compared to Hashtable and Dictionary<object, object>. For this test, I added n items to each collection, then randomly accessed n/2 items: So, what's going on here? Well, ListDictionary is implemented as a linked list of key/value pairs; all operations on the dictionary require an O(n) search through the list. However, for small n, the constant factor that big-o notation doesn't measure is much lower than the hashing overhead of Hashtable or Dictionary. HybridDictionary combines a Hashtable and ListDictionary; for small n, it uses a backing ListDictionary, but switches to a Hashtable when it gets to 9 items (you can see the point it switches from a ListDictionary to Hashtable in the graph). Apart from that, it's got very similar performance to Hashtable. So why would you want to use either of these? In short, you wouldn't. Any gain in performance by using ListDictionary over Dictionary<TKey, TValue> would be offset by the generic dictionary not having to cast or box the items you store, something the graphs above don't measure. Only if the performance of the dictionary is vital, the dictionary will hold less than 30 items, and you don't need type safety, would you use ListDictionary over the generic Dictionary. And even then, there's probably more useful performance gains you can make elsewhere.

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• How to run RCU from the command line

  - by Kevin Smith

  When I was trying to figure out how to run RCU on 64-bit Linux I found this post. It shows how to run RCU from the command line. It didn't actually work for me, so you can see my post on how to run RCU on 64-bit Linux. But, seeing how to run RCU from the command got me started thinking about running RCU from the command line to create the schema for WebCenter Content. That post got me part of the way there since it shows how run RCU silently from the command line, but to do this you need to know the name of the RCU component for WebCenter Content. I poked around in the RCU files and found the component name for WCC is CONTENTSERVER11. There is a contentserver11 directory in rcuHome/rcu/integration and when you look at the contentserver11.xml file you will see <RepositoryConfig COMP_ID="CONTENTSERVER11"> With the component name for WCC in hand I was able to use this command line to run RCU and create the schema for WCC. .../rcuHome/bin/rcu -silent -createRepository -databaseType ORACLE -connectString localhost:1521:orcl1 -dbUser sys -dbRole sysdba -schemaPrefix TEST -component CONTENTSERVER11 -f <rcu_passwords.txt To make the silent part work and not have it prompt you for the passwords needed (sys password and password for each schema) you use the -f option and specify a file containing the passwords, one per line, in the order the components are listed on the -component argument. Here is the output from rcu when I ran the above command. Processing command line ....Repository Creation Utility - Checking PrerequisitesChecking Global PrerequisitesRepository Creation Utility - Checking PrerequisitesChecking Component PrerequisitesRepository Creation Utility - Creating TablespacesValidating and Creating TablespacesRepository Creation Utility - CreateRepository Create in progress.Percent Complete: 0...Percent Complete: 100Repository Creation Utility: Create - Completion SummaryDatabase details:Host Name              : localhostPort                   : 1521Service Name           : ORCL1Connected As           : sysPrefix for (prefixable) Schema Owners : TESTRCU Logfile            : /u01/app/oracle/logdir.2012-09-26_07-53/rcu.logComponent schemas created:Component                            Status  LogfileOracle Content Server 11g - Complete Success /u01/app/oracle/logdir.2012-09-26_07-53/contentserver11.logRepository Creation Utility - Create : Operation Completed This works fine if you want to use the default tablespace sizes and options, but there does not seem to be a way to specify the tablespace options on the command line. You can specify the name of the tablespace and temp tablespace, but they must already exist in the database before running RCU. I guess you can always create the tablespaces first using your desired sizes and options and then run RCU and specify the tablespaces you created. When looking up the command line options in the RCU doc I found it has the list of components for each product that it supports. See Appendix B in the RCU User's Guide.

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• Reference Data Management and Master Data: Are Relation ?

  - by Mala Narasimharajan

  Submitted By:  Rahul Kamath  Oracle Data Relationship Management (DRM) has always been extremely powerful as an Enterprise Master Data Management (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 restructuring sales territories to enable equitable distribution of leads to sales teams following the acquisition of new products, or adding additional cost centers to enable fine grain control over expenses. 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? How does it relate to Master Data? Reference data is a close cousin of master data. While master data is challenged with problems of unique identification, 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 gives them contextual value. In fact, the creation of a new master data element may require new reference data to be created. For example, when a European company acquires a US business, chances are that they will now need to adapt their product line taxonomy to include a new category to describe the newly acquired US product line. Further, the cross-border transaction will also result in a revised geo hierarchy. The addition of new products represents changes to master data while changes to product categories and geo hierarchy are examples of reference data changes.1 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. Change Management: 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. References 1 Master Data versus Reference Data, Malcolm Chisholm, April 1, 2006.

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• Thoughts on my new template language/HTML generator?

  - by Ralph

  I guess I should have pre-faced this with: Yes, I know there is no need for a new templating language, but I want to make a new one anyway, because I'm a fool. That aside, how can I improve my language: Let's start with an example: using "html5" using "extratags" html { head { title "Ordering Notice" jsinclude "jquery.js" } body { h1 "Ordering Notice" p "Dear @name," p "Thanks for placing your order with @company. It's scheduled to ship on {@ship_date|dateformat}." p "Here are the items you've ordered:" table { tr { th "name" th "price" } for(@item in @item_list) { tr { td @item.name td @item.price } } } if(@ordered_warranty) p "Your warranty information will be included in the packaging." p(class="footer") { "Sincerely," br @company } } } The "using" keyword indicates which tags to use. "html5" might include all the html5 standard tags, but your tags names wouldn't have to be based on their HTML counter-parts at all if you didn't want to. The "extratags" library for example might add an extra tag, called "jsinclude" which gets replaced with something like <script type="text/javascript" src="@content"></script> Tags can be optionally be followed by an opening brace. They will automatically be closed at the closing brace. If no brace is used, they will be closed after taking one element. Variables are prefixed with the @ symbol. They may be used inside double-quoted strings. I think I'll use single-quotes to indicate "no variable substitution" like PHP does. Filter functions can be applied to variables like @variable|filter. Arguments can be passed to the filter @variable|filter:@arg1,arg2="y" Attributes can be passed to tags by including them in (), like p(class="classname"). You will also be able to include partial templates like: for(@item in @item_list) include("item_partial", item=@item) Something like that I'm thinking. The first argument will be the name of the template file, and subsequent ones will be named arguments where @item gets the variable name "item" inside that template. I also want to have a collection version like RoR has, so you don't even have to write the loop. Thoughts on this and exact syntax would be helpful :) Some questions: Which symbol should I use to prefix variables? @ (like Razor), $ (like PHP), or something else? Should the @ symbol be necessary in "for" and "if" statements? It's kind of implied that those are variables. Tags and controls (like if,for) presently have the exact same syntax. Should I do something to differentiate the two? If so, what? This would make it more clear that the "tag" isn't behaving like just a normal tag that will get replaced with content, but controls the flow. Also, it would allow name-reuse. Do you like the attribute syntax? (round brackets) How should I do template inheritance/layouts? In Django, the first line of the file has to include the layout file, and then you delimit blocks of code which get stuffed into that layout. In CakePHP, it's kind of backwards, you specify the layout in the controller.view function, the layout gets a special $content_for_layout variable, and then the entire template gets stuffed into that, and you don't need to delimit any blocks of code. I guess Django's is a little more powerful because you can have multiple code blocks, but it makes your templates more verbose... trying to decide what approach to take Filtered variables inside quotes: "xxx {@var|filter} yyy" "xxx @{var|filter} yyy" "xxx @var|filter yyy" i.e, @ inside, @ outside, or no braces at all. I think no-braces might cause problems, especially when you try adding arguments, like @var|filter:arg="x", then the quotes would get confused. But perhaps a braceless version could work for when there are no quotes...? Still, which option for braces, first or second? I think the first one might be better because then we're consistent... the @ is always nudged up against the variable. I'll add more questions in a few minutes, once I get some feedback.

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• Sneak Peak: Social Developer Program at JavaOne

  - by Mike Stiles

  By guest blogger Roland Smart We're just days away from what is gunning to be the most exciting installment of OpenWorld to date, so how about an exciting sneak peak at the very first Social Developer Program? If your first thought is, "What's a social developer?" you're not alone. It’s an emerging term and one we think will gain prominence as social experiences become more prevalent in enterprise applications. For those who keep an eye on the ever-evolving Facebook platform, you'll recall that they recently rebranded their PDC (preferred developer consultant) group as the PMD (preferred marketing developer), signaling the importance of development resources inside the marketing organization to unlock the potential of social. The marketing developer they're referring to could be considered a social developer in a broader context. While it's true social has really blossomed in the marketing context and CMOs are winning more and more technical resources, social is starting to work its way more deeply into the enterprise with the help of developers that work outside marketing. Developers, like the rest of us, have fallen in "like" with social functionality and are starting to imagine how social can transform enterprise applications in the way it has consumer-facing experiences. The thesis of my presentation is that social developers will take many pages from the marketing playbook as they apply social inside the enterprise. To support this argument, lets walk through a range of enterprise applications and explore how consumer-facing social experiences might be interpreted in this context. Here's one example of how a social experience could be integrated into a sales enablement application. As a marketer, I spend a great deal of time collaborating with my sales colleagues, so I have good insight into their working process. While at Involver, we grew our sales team quickly, and it became evident some of our processes broke with scale. For example, we used to have weekly team meetings at which we'd discuss what was working and what wasn't from a messaging perspective. One aspect of these sessions focused on "objections" and "responses," where the salespeople would walk through common objections to purchasing and share appropriate responses. We tried to map each context to best answers and we'd capture these on a wiki page. As our team grew, however, participation at scale just wasn't tenable, and our wiki pages quickly lost their freshness. Imagine giving salespeople a place where they could submit common objections and responses for their colleagues to see, sort, comment on, and vote on. What you'd get is an up-to-date and relevant repository of information. And, if you supported an application like this with a social graph, it would be possible to make good recommendations to individual sales people about the objections they'd likely hear based on vertical, product, region or other graph data. Taking it even further, you could build in a badging/game element to reward those salespeople who participate the most. Both these examples are based on proven models at work inside consumer-facing applications. If you want to learn about how HR, Operations, Product Development and Customer Support can leverage social experiences, you’re welcome to join us at JavaOne or join our Social Developer Community to find some of the presentations after OpenWorld.

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• Use a Fake Http Channel to Unit Test with HttpClient

  - by Steve Michelotti

  Applications get data from lots of different sources. The most common is to get data from a database or a web service. Typically, we encapsulate calls to a database in a Repository object and we create some sort of IRepository interface as an abstraction to decouple between layers and enable easier unit testing by leveraging faking and mocking. This works great for database interaction. However, when consuming a RESTful web service, this is is not always the best approach. The WCF Web APIs that are available on CodePlex (current drop is Preview 3) provide a variety of features to make building HTTP REST services more robust. When you download the latest bits, you’ll also find a new HttpClient which has been updated for .NET 4.0 as compared to the one that shipped for 3.5 in the original REST Starter Kit. The HttpClient currently provides the best API for consuming REST services on the .NET platform and the WCF Web APIs provide a number of extension methods which extend HttpClient and make it even easier to use. Let’s say you have a client application that is consuming an HTTP service – this could be Silverlight, WPF, or any UI technology but for my example I’ll use an MVC application: 1: using System; 2: using System.Net.Http; 3: using System.Web.Mvc; 4: using FakeChannelExample.Models; 5: using Microsoft.Runtime.Serialization; 6:   7: namespace FakeChannelExample.Controllers 8: { 9: public class HomeController : Controller 10: { 11: private readonly HttpClient httpClient; 12:   13: public HomeController(HttpClient httpClient) 14: { 15: this.httpClient = httpClient; 16: } 17:   18: public ActionResult Index() 19: { 20: var response = httpClient.Get("Person(1)"); 21: var person = response.Content.ReadAsDataContract<Person>(); 22:   23: this.ViewBag.Message = person.FirstName + " " + person.LastName; 24: 25: return View(); 26: } 27: } 28: } On line #20 of the code above you can see I’m performing an HTTP GET request to a Person resource exposed by an HTTP service. On line #21, I use the ReadAsDataContract() extension method provided by the WCF Web APIs to serialize to a Person object. In this example, the HttpClient is being passed into the constructor by MVC’s dependency resolver – in this case, I’m using StructureMap as an IoC and my StructureMap initialization code looks like this: 1: using StructureMap; 2: using System.Net.Http; 3:   4: namespace FakeChannelExample 5: { 6: public static class IoC 7: { 8: public static IContainer Initialize() 9: { 10: ObjectFactory.Initialize(x => 11: { 12: x.For<HttpClient>().Use(() => new HttpClient("http://localhost:31614/")); 13: }); 14: return ObjectFactory.Container; 15: } 16: } 17: } My controller code currently depends on a concrete instance of the HttpClient. Now I *could* create some sort of interface and wrap the HttpClient in this interface and use that object inside my controller instead – however, there are a few why reasons that is not desirable: For one thing, the API provided by the HttpClient provides nice features for dealing with HTTP services. I don’t really *want* these to look like C# RPC method calls – when HTTP services have REST features, I may want to inspect HTTP response headers and hypermedia contained within the message so that I can make intelligent decisions as to what to do next in my workflow (although I don’t happen to be doing these things in my example above) – this type of workflow is common in hypermedia REST scenarios. If I just encapsulate HttpClient behind some IRepository interface and make it look like a C# RPC method call, it will become difficult to take advantage of these types of things. Second, it could get pretty mind-numbing to have to create interfaces all over the place just to wrap the HttpClient. Then you’re probably going to have to hard-code HTTP knowledge into your code to formulate requests rather than just “following the links” that the hypermedia in a message might provide. Third, at first glance it might appear that we need to create an interface to facilitate unit testing, but actually it’s unnecessary. Even though the code above is dependent on a concrete type, it’s actually very easy to fake the data in a unit test. The HttpClient provides a Channel property (of type HttpMessageChannel) which allows you to create a fake message channel which can be leveraged in unit testing. In this case, what I want is to be able to write a unit test that just returns fake data. I also want this to be as re-usable as possible for my unit testing. I want to be able to write a unit test that looks like this: 1: [TestClass] 2: public class HomeControllerTest 3: { 4: [TestMethod] 5: public void Index() 6: { 7: // Arrange 8: var httpClient = new HttpClient("http://foo.com"); 9: httpClient.Channel = new FakeHttpChannel<Person>(new Person { FirstName = "Joe", LastName = "Blow" }); 10:   11: HomeController controller = new HomeController(httpClient); 12:   13: // Act 14: ViewResult result = controller.Index() as ViewResult; 15:   16: // Assert 17: Assert.AreEqual("Joe Blow", result.ViewBag.Message); 18: } 19: } Notice on line #9, I’m setting the Channel property of the HttpClient to be a fake channel. I’m also specifying the fake object that I want to be in the response on my “fake” Http request. I don’t need to rely on any mocking frameworks to do this. All I need is my FakeHttpChannel. The code to do this is not complex: 1: using System; 2: using System.IO; 3: using System.Net.Http; 4: using System.Runtime.Serialization; 5: using System.Threading; 6: using FakeChannelExample.Models; 7:   8: namespace FakeChannelExample.Tests 9: { 10: public class FakeHttpChannel<T> : HttpClientChannel 11: { 12: private T responseObject; 13:   14: public FakeHttpChannel(T responseObject) 15: { 16: this.responseObject = responseObject; 17: } 18:   19: protected override HttpResponseMessage Send(HttpRequestMessage request, CancellationToken cancellationToken) 20: { 21: return new HttpResponseMessage() 22: { 23: RequestMessage = request, 24: Content = new StreamContent(this.GetContentStream()) 25: }; 26: } 27:   28: private Stream GetContentStream() 29: { 30: var serializer = new DataContractSerializer(typeof(T)); 31: Stream stream = new MemoryStream(); 32: serializer.WriteObject(stream, this.responseObject); 33: stream.Position = 0; 34: return stream; 35: } 36: } 37: } The HttpClientChannel provides a Send() method which you can override to return any HttpResponseMessage that you want. You can see I’m using the DataContractSerializer to serialize the object and write it to a stream. That’s all you need to do. In the example above, the only thing I’ve chosen to do is to provide a way to return different response objects. But there are many more features you could add to your own re-usable FakeHttpChannel. For example, you might want to provide the ability to add HTTP headers to the message. You might want to use a different serializer other than the DataContractSerializer. You might want to provide custom hypermedia in the response as well as just an object or set HTTP response codes. This list goes on. This is the just one example of the really cool features being added to the next version of WCF to enable various HTTP scenarios. The code sample for this post can be downloaded here.

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• H1 Visa interview tips–What you must know before attending the interview?

  - by Gopinath

  USA’s H1 visa allows highly qualified professionals from other countries to work in America. Many IT professionals in India aspire to go to USA on H1 and work for their clients. Recently I had a chance to study H1 visa process to help one of my friends and I would like to share what I learned. With the assumption that your H1 petition is approved and you got an interview scheduled at US Embassy for your visa stamping, here are tips you must know before attending the interview Dress Code – Formals Say no to casuals or any fancy dress when you attend the interview. It’s not a party or friends home you are visiting. Consider H1 Visa interview as your job interview and dress up in formals. There is no option B for your, you must be in formals. A plain formal shirt with a matching pant is suggested for men. Tie and Suit would not be required, but if you are a professional at management level you can consider wearing suit. Women can wear either formal Salwar or formal pant-shirt. Avoid heavy jewellery, wear what is must as per your tradition or culture. Body Language -  Smile on your face Your body language reflects what you are and what’s going on in your mind. Don’t be nervous or restless, be relaxed and wear a beautiful smile on your face. A smile is a curve that sets everything straight. When you are called for the interview, greet the interviewer with a beautiful smile. Say Good Morning/Afternoon/Evening depending on time you are visiting them. Whenever appropriate say Thank You. Generally American professionals are very friendly people and they reciprocate for your greetings. Make sure that you make them comfortable to start the interview. Carry original documents in a separate folder I don’t want to talk much about the documents that are required for your H1B interview as it’s big subject on it’s own and it requires a separate post. I assume that your consultant or employer helped you in gathering all the required documents like – petition, DS 160 forms, education & job related documents, resume, interview call letters, client letters, etc. For all the documents you are going to submit at the interview make sure that you have originals in a separate folder.  If required interviewer may ask you show the originals of any of the document you submitted for visa processing. Don’t mix the original documents with the documents you need to submit for interview. Have a separate folder for them. For those who are going to stamping along with their spouse and children, they need to carry few extra original documents like – marriage certificate, marriage photos(30 numbers)/album, birth certificates, passports, education and profession related certificates of the spouse and children. Know your role & responsibilities The interviewer will ask you questions on your roles and responsibilities at client location. Be clear what is your day to day tasks at client place and prepared to face detailed questions on the same. When asked explain clearly and also make sure what you say is inline with what is mentioned in your petition and client invitation letter. At times they may ask you questions specific to the project/technology you are going to work. So doing some homework in this area will help you easily answer the questions. Failing to answer basic questions on your role & responsibilities may result in rejection. You work for your Employer at Client location but NOT FOR CLIENT One of the important things to keep in mind that you work for your employer and you are being deputed to client location on a work visa.  Your employer is going to be solely responsible for your salary, work, promotion, pay hikes or what so ever during your stay at USA. Your client will not be responsible for anything. Lets say you are employed with Company X in India and they are applying for H1B to work at your client(ex: Microsoft) in USA, you must keep in my mind that Microsoft is not your employer. Microsoft will not pay your salaries or responsible for any employment related activities. Company X will be solely responsible for all your employer related activities. If you don’t get this correctly and say to Visa interviewer that your client is responsible, then you may get into troubles. Know your client It’s always good to know the clients with whom you are going to work in USA and their business. If your client is a well know organisation then you may not get many questions from interviewer else you need to be well prepared to provide details like – nature of business, location, size of the organisation, etc.  Get to know the basic details about your client and be confident while providing those details to the interviewer. Also make sure that you never talk about any confidential details of your client projects and business. Revealing confidential details of your client may land your job itself in soup. Make sure that your spouse is also in sync with you If you’ve applied a H4 visa for your spouse along with your H1, make sure that spouse is in sync with you. Your spouse also should know the basic details of your job, your employer, client and location where you will be travelling. Your spouse should also be prepared to answers questions related to marriage, their profession(if working), kids, education, etc. Interviewers will try to asses your spouse communication skills, whereabouts while staying in USA and would they prefer to work USA or not. On H4, which is a dependent visa, your spouse is not allowed to work in USA and at any point your spouse should not show the intentions to search for work in USA. Less luggage more comfort You would have definitely heard that there are lot of restrictions on what you can carry along with you to an US Embassy while attending the interview. To be frank it’s not good to say there are many restrictions, but there are a hell a lot of restrictions. There are unbelievable restrictions and it’s for the safety of everyone. You are not allowed to carry mobile phones, CD/DVDs, USBs, bank cards, cameras, cosmetics, food(except baby food), water, wallets, backpacks, sealed covers, etc. Trust me most of the things we carry with us regularly every day are not allowed inside. As there are 100s of restrictions, it would be easier if you understand what you can carry along with you and just carry them alone. Ask your employer/consultant to provide you a checklist of items that you can carry. Most what you would require are H1B related documents provided by the employer/consultant Photographs All original documents supporting your H1B Passports Some cash for your travel expenses (avoid coins) Any important phone number / details written in a paper(like your cab driver number, etc.) If you carry restricted stuff then you will be stopped at security checks, you have to find people who can safely keep all the restricted items. Due to heavy restrictions in and around the US Embassy you will not find any  place to keep your luggage. So just carry the bare minimum things required so that you feel more comfortable. Useful Links THE U.S. NON IMMIGRANT VISA APPLICATION PROCESS U.S VISA SECURITY REGULATIONS GENERAL FAQS Hope this information is helpful to you and best of luck for your interview. Creative commons Image credit: Flickr/ alexfrance, vinothchandar. hughelectronic, architratan, striatic

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• NUMA-aware placement of communication variables

  - by Dave

  For classic NUMA-aware programming I'm typically most concerned about simple cold, capacity and compulsory misses and whether we can satisfy the miss by locally connected memory or whether we have to pull the line from its home node over the coherent interconnect -- we'd like to minimize channel contention and conserve interconnect bandwidth. That is, for this style of programming we're quite aware of where memory is homed relative to the threads that will be accessing it. Ideally, a page is collocated on the node with the thread that's expected to most frequently access the page, as simple misses on the page can be satisfied without resorting to transferring the line over the interconnect. The default "first touch" NUMA page placement policy tends to work reasonable well in this regard. When a virtual page is first accessed, the operating system will attempt to provision and map that virtual page to a physical page allocated from the node where the accessing thread is running. It's worth noting that the node-level memory interleaving granularity is usually a multiple of the page size, so we can say that a given page P resides on some node N. That is, the memory underlying a page resides on just one node. But when thinking about accesses to heavily-written communication variables we normally consider what caches the lines underlying such variables might be resident in, and in what states. We want to minimize coherence misses and cache probe activity and interconnect traffic in general. I don't usually give much thought to the location of the home NUMA node underlying such highly shared variables. On a SPARC T5440, for instance, which consists of 4 T2+ processors connected by a central coherence hub, the home node and placement of heavily accessed communication variables has very little impact on performance. The variables are frequently accessed so likely in M-state in some cache, and the location of the home node is of little consequence because a requester can use cache-to-cache transfers to get the line. Or at least that's what I thought. Recently, though, I was exploring a simple shared memory point-to-point communication model where a client writes a request into a request mailbox and then busy-waits on a response variable. It's a simple example of delegation based on message passing. The server polls the request mailbox, and having fetched a new request value, performs some operation and then writes a reply value into the response variable. As noted above, on a T5440 performance is insensitive to the placement of the communication variables -- the request and response mailbox words. But on a Sun/Oracle X4800 I noticed that was not the case and that NUMA placement of the communication variables was actually quite important. For background an X4800 system consists of 8 Intel X7560 Xeons . Each package (socket) has 8 cores with 2 contexts per core, so the system is 8x8x2. Each package is also a NUMA node and has locally attached memory. Every package has 3 point-to-point QPI links for cache coherence, and the system is configured with a twisted ladder "mobius" topology. The cache coherence fabric is glueless -- there's not central arbiter or coherence hub. The maximum distance between any two nodes is just 2 hops over the QPI links. For any given node, 3 other nodes are 1 hop distant and the remaining 4 nodes are 2 hops distant. Using a single request (client) thread and a single response (server) thread, a benchmark harness explored all permutations of NUMA placement for the two threads and the two communication variables, measuring the average round-trip-time and throughput rate between the client and server. In this benchmark the server simply acts as a simple transponder, writing the request value plus 1 back into the reply field, so there's no particular computation phase and we're only measuring communication overheads. In addition to varying the placement of communication variables over pairs of nodes, we also explored variations where both variables were placed on one page (and thus on one node) -- either on the same cache line or different cache lines -- while varying the node where the variables reside along with the placement of the threads. The key observation was that if the client and server threads were on different nodes, then the best placement of variables was to have the request variable (written by the client and read by the server) reside on the same node as the client thread, and to place the response variable (written by the server and read by the client) on the same node as the server. That is, if you have a variable that's to be written by one thread and read by another, it should be homed with the writer thread. For our simple client-server model that means using split request and response communication variables with unidirectional message flow on a given page. This can yield up to twice the throughput of less favorable placement strategies. Our X4800 uses the QPI 1.0 protocol with source-based snooping. Briefly, when node A needs to probe a cache line it fires off snoop requests to all the nodes in the system. Those recipients then forward their response not to the original requester, but to the home node H of the cache line. H waits for and collects the responses, adjudicates and resolves conflicts and ensures memory-model ordering, and then sends a definitive reply back to the original requester A. If some node B needed to transfer the line to A, it will do so by cache-to-cache transfer and let H know about the disposition of the cache line. A needs to wait for the authoritative response from H. So if a thread on node A wants to write a value to be read by a thread on node B, the latency is dependent on the distances between A, B, and H. We observe the best performance when the written-to variable is co-homed with the writer A. That is, we want H and A to be the same node, as the writer doesn't need the home to respond over the QPI link, as the writer and the home reside on the very same node. With architecturally informed placement of communication variables we eliminate at least one QPI hop from the critical path. Newer Intel processors use the QPI 1.1 coherence protocol with home-based snooping. As noted above, under source-snooping a requester broadcasts snoop requests to all nodes. Those nodes send their response to the home node of the location, which provides memory ordering, reconciles conflicts, etc., and then posts a definitive reply to the requester. In home-based snooping the snoop probe goes directly to the home node and are not broadcast. The home node can consult snoop filters -- if present -- and send out requests to retrieve the line if necessary. The 3rd party owner of the line, if any, can respond either to the home or the original requester (or even to both) according to the protocol policies. There are myriad variations that have been implemented, and unfortunately vendor terminology doesn't always agree between vendors or with the academic taxonomy papers. The key is that home-snooping enables the use of a snoop filter to reduce interconnect traffic. And while home-snooping might have a longer critical path (latency) than source-based snooping, it also may require fewer messages and less overall bandwidth. It'll be interesting to reprise these experiments on a platform with home-based snooping. While collecting data I also noticed that there are placement concerns even in the seemingly trivial case when both threads and both variables reside on a single node. Internally, the cores on each X7560 package are connected by an internal ring. (Actually there are multiple contra-rotating rings). And the last-level on-chip cache (LLC) is partitioned in banks or slices, which with each slice being associated with a core on the ring topology. A hardware hash function associates each physical address with a specific home bank. Thus we face distance and topology concerns even for intra-package communications, although the latencies are not nearly the magnitude we see inter-package. I've not seen such communication distance artifacts on the T2+, where the cache banks are connected to the cores via a high-speed crossbar instead of a ring -- communication latencies seem more regular.

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• Planning development when academic research is involved

  - by Another Anonymous User

  Dear fellow programmers, how do you do "software planning" when academic research is involved? And, on a side note, how do you convince your boss that writing software is not like building a house and it's more like writing a novel? The gory details are below. I am in charge of a small dev team working in a research lab. We started developing a software with the purpose of going public one day (i.e. sell and make money off that). Such software depends on, amongst other things, at least two independent research lines: that is, there are at least two Ph.D. candidates that will, hopefully, one day come out with a working implementation of what we need. The main software depends also on other, more concrete resources that we as developers can take care of: graphics rendering, soft bodies deformation, etc. My boss asked me to write the specifications, requirements AND a bloody GANTT chart of the entire project. Faced with the fact that I don't have a clue about the research part, and that such research is fundamental for the software, he said "make assumptions." For the clarity of the argument, he is a professor whose Ph.D. students should come up with the research we need. And he comes from a strictly engineering background: plan everything first, write down specifications and only then write down code that "it's the last part". What I am doing now: I broke down the product in features; each 'feature' is, de facto, a separate product; Each feature is built on top of the previous one; Once a feature (A) has a working prototype the team can start working on the next feature (B), while QA for is being done for A (if money allows, more people can be brought in, etc.); Features that depend on research will come last: by then, hopefully, the research part will be completed (when is still a big question) ; Also, I set the team to use SCRUM for the development of 'version 1.0', due in a few months. This deadline could be set based on reasonable assumptions: we listed all required features, we counted our availability, and we gave a reasonable estimate. So my questions, again, are: How do I make my boss happy while at the same time get something out the door? How do I write specifications for something we -the developers- have no clue whether it's possible to do or not? (We still haven't decided which libraries to use for some tasks; we'll do so when we'll need to) How do I get the requirements for that, given that there are yet no clients nor investors, just lots of interests and promises? How do I get peace in the world? I am sure at least one of my questions will be answered :) ps: I am writing this anonymously since a potential investor might backfire if this is discovered. Hope you'll understand. However I must say I do not like this mentality of 'hiding the truth': this program will likely benefit many, and not being able to talk openly about this (with my name and my reputation attached) feels like censorship. But alas, I care more about your suggestions now.

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• Swap not available on System Monitor

  - by Zaki

  I had a swap partition of 1GB (RAM 1GB, Ubuntu 12.04 lts). Now swap is not shown on System Monitor neither can I hibernate my pc (sudo pm-hibernate). blkid output: /dev/sda1: UUID="B8B4FBB1B4FB706C" TYPE="ntfs" /dev/sda2: UUID="2ea7d608-2d89-4e41-9436-d05cb3ce8871" TYPE="swap" /dev/sda3: UUID="3219d03a-67e4-454b-8ce7-a27831846e35" TYPE="ext4" /dev/sda5: LABEL="Softwares" UUID="AC1CC3301CC2F47C" TYPE="ntfs" /dev/sda6: LABEL="Education" UUID="1E103E6C103E4B53" TYPE="ntfs" /dev/sda7: LABEL="Recreation" UUID="2CC8D181C8D149AA" TYPE="ntfs" /dev/sda8: LABEL="Miscellaneous" UUID="0274D6B174D6A727" TYPE="ntfs" /etc/fstab # <file system> <mount point> <type> <options> <dump> <pass> proc /proc proc nodev,noexec,nosuid 0 0 # / was on /dev/sda6 during installation UUID=3219d03a-67e4-454b-8ce7-a27831846e35 / ext4 errors=remount-ro 0 1 # swap was on /dev/sda5 during installation UUID=2ea7d608-2d89-4e41-9436-d05cb3ce8871 none swap sw 0 0 free -m total used free shared buffers cached Mem: 991 867 123 0 27 418 -/+ buffers/cache: 421 569 Swap: 0 0 0 cat /proc/swaps Filename Type Size Used Priority fdisk -l Disk /dev/sda: 160.0 GB, 160041885696 bytes 255 heads, 63 sectors/track, 19457 cylinders, total 312581808 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x9f369f36 Device Boot Start End Blocks Id System /dev/sda1 * 63 31471334 15735636 7 HPFS/NTFS/exFAT /dev/sda2 31471616 33470447 999416 82 Linux swap / Solaris /dev/sda3 33472512 62539775 14533632 83 Linux /dev/sda4 62541045 312592769 125025862+ f W95 Ext'd (LBA) /dev/sda5 62541108 125066024 31262458+ 7 HPFS/NTFS/exFAT /dev/sda6 125066088 187591004 31262458+ 7 HPFS/NTFS/exFAT /dev/sda7 187591068 250115984 31262458+ 7 HPFS/NTFS/exFAT /dev/sda8 250116048 312576704 31230328+ 7 HPFS/NTFS/exFAT swapon --all swapon: /dev/sda2: swapon failed: Invalid argument dmesg | grep -A 5 -B 5 -i swap [ 9.487404] EXT4-fs (sda3): ext4_orphan_cleanup: deleting unreferenced inode 131645 [ 9.487413] EXT4-fs (sda3): ext4_orphan_cleanup: deleting unreferenced inode 131330 [ 9.487418] EXT4-fs (sda3): 16 orphan inodes deleted [ 9.487420] EXT4-fs (sda3): recovery complete [ 9.578600] EXT4-fs (sda3): mounted filesystem with ordered data mode. Opts: (null) [ 20.580539] Swap area shorter than signature indicates [ 20.588363] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready [ 20.619443] udevd[330]: starting version 175 [ 20.649959] lp: driver loaded but no devices found [ 20.662972] [drm] Initialized drm 1.1.0 20060810 [ 20.675515] i915 0000:00:02.0: setting latency timer to 64 -- [ 72.288573] PM: thaw of drv:sr dev:3:0:0:0 complete after 178.143 msecs [ 72.288578] PM: thaw of drv:scsi_device dev:3:0:0:0 complete after 178.136 msecs [ 72.299677] PM: thaw of drv:scsi_device dev:2:0:0:0 complete after 189.270 msecs [ 72.309473] PM: thaw of devices complete after 202.763 msecs [ 72.309668] PM: writing image. [ 72.309670] PM: Cannot find swap device, try swapon -a. [ 72.309699] PM: Cannot get swap writer [ 72.329896] Restarting tasks ... done. [ 72.331777] PM: Basic memory bitmaps freed [ 72.331792] video LNXVIDEO:00: Restoring backlight state [ 72.420048] option1 ttyUSB0: option_instat_callback: error -84 [ 72.804047] option1 ttyUSB0: option_instat_callback: error -84 -- [ 145.960625] sd 7:0:0:0: Attached scsi generic sg2 type 0 [ 145.972036] sd 7:0:0:0: [sdb] Attached SCSI removable disk [ 172.430508] PPP BSD Compression module registered [ 172.455583] PPP Deflate Compression module registered [ 332.260789] type=1400 audit(1381814763.342:27): apparmor="DENIED" operation="capable" parent=1 profile="/usr/sbin/cupsd" pid=636 comm="cupsd" pid=636 comm="cupsd" capability=36 capname="block_suspend" [ 1913.030998] Swap area shorter than signature indicates [ 2022.530155] type=1400 audit(1381816453.610:28): apparmor="DENIED" operation="capable" parent=1 profile="/usr/sbin/cupsd" pid=636 comm="cupsd" pid=636 comm="cupsd" capability=36 capname="block_suspend" [ 4062.729509] Swap area shorter than signature indicates Please help. Thanks in advance. df -h Filesystem Size Used Avail Use% Mounted on /dev/sda3 14G 6.1G 7.0G 47% / udev 488M 4.0K 488M 1% /dev tmpfs 199M 868K 198M 1% /run none 5.0M 4.0K 5.0M 1% /run/lock none 496M 224K 496M 1% /run/shm

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• ODI 12c - Aggregating Data

  - by David Allan

  This posting will look at the aggregation component that was introduced in ODI 12c. For many ETL tool users this shouldn't be a big surprise, its a little different than ODI 11g but for good reason. You can use this component for composing data with relational like operations such as sum, average and so forth. Also, Oracle SQL supports special functions called Analytic SQL functions, you can use a specially configured aggregation component or the expression component for these now in ODI 12c. In database systems an aggregate transformation is a transformation where the values of multiple rows are grouped together as input on certain criteria to form a single value of more significant meaning - that's exactly the purpose of the aggregate component. In the image below you can see the aggregate component in action within a mapping, for how this and a few other examples are built look at the ODI 12c Aggregation Viewlet here - the viewlet illustrates a simple aggregation being built and then some Oracle analytic SQL such as AVG(EMP.SAL) OVER (PARTITION BY EMP.DEPTNO) built using both the aggregate component and the expression component. In 11g you used to just write the aggregate expression directly on the target, this made life easy for some cases, but it wan't a very obvious gesture plus had other drawbacks with ordering of transformations (agg before join/lookup. after set and so forth) and supporting analytic SQL for example - there are a lot of postings from creative folks working around this in 11g - anything from customizing KMs, to bypassing aggregation analysis in the ODI code generator. The aggregate component has a few interesting aspects. 1. Firstly and foremost it defines the attributes projected from it - ODI automatically will perform the grouping all you do is define the aggregation expressions for those columns aggregated. In 12c you can control this automatic grouping behavior so that you get the code you desire, so you can indicate that an attribute should not be included in the group by, that's what I did in the analytic SQL example using the aggregate component. 2. The component has a few other properties of interest; it has a HAVING clause and a manual group by clause. The HAVING clause includes a predicate used to filter rows resulting from the GROUP BY clause. Because it acts on the results of the GROUP BY clause, aggregation functions can be used in the HAVING clause predicate, in 11g the filter was overloaded and used for both having clause and filter clause, this is no longer the case. If a filter is after an aggregate, it is after the aggregate (not sometimes after, sometimes having).  3. The manual group by clause let's you use special database grouping grammar if you need to. For example Oracle has a wealth of highly specialized grouping capabilities for data warehousing such as the CUBE function. If you want to use specialized functions like that you can manually define the code here. The example below shows the use of a manual group from an example in the Oracle database data warehousing guide where the SUM aggregate function is used along with the CUBE function in the group by clause. The SQL I am trying to generate looks like the following from the data warehousing guide; SELECT channel_desc, calendar_month_desc, countries.country_iso_code,       TO_CHAR(SUM(amount_sold), '9,999,999,999') SALES$ FROM sales, customers, times, channels, countries WHERE sales.time_id=times.time_id AND sales.cust_id=customers.cust_id AND   sales.channel_id= channels.channel_id  AND customers.country_id = countries.country_id  AND channels.channel_desc IN   ('Direct Sales', 'Internet') AND times.calendar_month_desc IN   ('2000-09', '2000-10') AND countries.country_iso_code IN ('GB', 'US') GROUP BY CUBE(channel_desc, calendar_month_desc, countries.country_iso_code); I can capture the source datastores, the filters and joins using ODI's dataset (or as a traditional flow) which enables us to incrementally design the mapping and the aggregate component for the sum and group by as follows; In the above mapping you can see the joins and filters declared in ODI's dataset, allowing you to capture the relationships of the datastores required in an entity-relationship style just like ODI 11g. The mix of ODI's declarative design and the common flow design provides for a familiar design experience. The example below illustrates flow design (basic arbitrary ordering) - a table load where only the employees who have maximum commission are loaded into a target. The maximum commission is retrieved from the bonus datastore and there is a look using employees as the driving table and only those with maximum commission projected. Hopefully this has given you a taster for some of the new capabilities provided by the aggregate component in ODI 12c. In summary, the actions should be much more consistent in behavior and more easily discoverable for users, the use of the components in a flow graph also supports arbitrary designs and the tool (rather than the interface designer) takes care of the realization using ODI's knowledge modules. Interested to know if a deep dive into each component is interesting for folks. Any thoughts? 

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• Oracle CRM On Demand Release 24 is Generally Available

  - by Richard Lefebvre

  Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 We are pleased to announce that Oracle CRM On Demand Release 24 is Generally Available as of October 25, 2013 Get smarter, more productive and the best value with Oracle CRM On Demand Release 24. Oracle CRM On Demand continues to be the most complete Software-as-a-Service (SaaS) CRM solution available. Now, with Release 24, organizations of all types and sizes benefit from actionable insight anywhere, anytime, as well as key enhancements in mobility, embedded social, analytics, integration and extensibility, and ease of use.Next Generation Mobile and Desktop Solutions : Oracle CRM On Demand Release 24 offers a complete set of mobile and desktop solutions that improve productivity by enabling reps to access and update information anywhere, anytime. Capabilities include: Oracle CRM On Demand Disconnected Mobile Sales (DMS) – A disconnected native iPad solution, DMS has been further streamlined mobile sales process by adding Structured Product Messaging to record brand specific call objectives, enhancements in HTML5 eDetailing including message response tracking and improvements in administration and configuration such as more field management options for read only fields, role management and enhanced logging. Oracle CRM On Demand Connected Mobile Sales. This add-on mobile service provides a configurable mobile solution on iOS, BlackBerry and now Android devices. You can access data from CRM On Demand in real time with a rich, native user experience, that is comfortable and familiar to current iOS, BlackBerry and Android users. New features also include Single Sign On to enhance security for mobile users.  Oracle CRM On Demand Desktop: This application centralizes essential CRM information in the familiar Microsoft Outlook environment,increasing user adoption and decreasing training costs. Users can manage CRM data while disconnected, then synchronize bi-directionally when they are back on the network. New in Oracle CRM On Demand Desktop Version 3 is the ability to synchronize by Books of Business, and improved Online Lookup. Mobile Browser Support: The following mobile device browsers are now supported: Apple iPhone, Apple iPad, Windows 8 Tablets, and Google Android. Leverage the Social Enterprise Engaging customers via social channels is rapidly becoming a significant key to enhanced customer experience as it provides proactive customer service, targeted messaging and greater intimacy throughout the entire customer lifecycle. Listening to customers on the social channels can identify a customers’ sphere of influence and the real value they bring to their organization, or the impact they can have on the opportunity. Servicing the customer’s need is the first step towards loyalty to a brand, integrating with social channels allows us to maximize brand affinity and virally expand customer engagements thus increasing revenue. Oracle CRM On Demand is leveraging the Social Enterprise through its integration with Oracle’s Social Relationship Management (SRM) product suite by providing out-of-the-box integration with Social Engagement and Monitoring (SEM), Social Marketing (SM) and Oracle Social Network (OSN). With Oracle CRM On Demand Release 24, users are able to create a service request from a social post via SEM and have leads entered on a SM lead form automatically entered into Oracle CRM On Demand along with the campaign, streamlining the lead qualification process. Get Smarter with Actionable Insight The difference between making good decisions and great decisions depends heavily upon the quality, structure, and availability of information at hand. Oracle CRM On Demand Release 24 expands upon its industry-leading analytics capabilities to provide greater business insight than ever before. New capabilities include flexible permissions on analytics reports folders, allowing for read only access to reports, and additional field and object coverage. Get More Productive with Powerful Tools Oracle CRM On Demand Release 24 introduces a new set of powerful capabilities designed to maximize productivity. A significant new feature for customizing Oracle CRM On Demand is a JavaScript API. The JS API allows customers to add new buttons, suppress existing buttons and even change what happens when a user clicks an existing button. Other usability enhancements, such as personalized related information applets, extended case insensitive search provide users with better, more intuitive, experience. Additional privileges for viewing private activities and notes allow administrators to reassign records as needed, and Custom Object management. Workflow has been added to the Order Item object; and now tasks can be assigned to a relative user, such as an Account Owner, allowing more complex business processes to be automated and adhered to. Get the Best Value Oracle CRM On Demand delivers unprecedented value with the broadest set of capabilities from a single-provider solution, the industry’s lowest total cost of ownership, the most on-demand deployment options, the deepest CRM expertise and experience of any CRM provider, and the most secure CRM in the cloud. With Release 24, Oracle CRM On Demand now includes even more enterprise-grade security, integration, and extensibility features, along with enhanced industry editions to save you time and money. New features include: Business Process Administration: A new privilege has been added that allows administrators to override a Business Process Administration rule.This privilege permits users to edit a locked record, or unlock a record, in the event of a material change that needs to be reflected per corporatepolicy. Additionally, the Products Detailed object has been added to Business Process Administration, enabling record locking and logic to be applied. Expanded Integration: Oracle continues to improve Web Services each release, by adding more object coverage enabling customers and partners to easily integrate with CRM On Demand. Bottom Line Oracle CRM On Demand Release 24 enables organizations to get smarter, get more productive, and get the best value, period. For more information on Oracle CRM On Demand Release 24, please visit oracle.com/crmondemand

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• Sprinkle Some Magik on that Java Virtual Machine

  - by Jim Connors

  GE Energy, through its Smallworld subsidiary, has been providing geospatial software solutions to the utility and telco markets for over 20 years.  One of the fundamental building blocks of their technology is a dynamically-typed object oriented programming language called Magik.  Like Java, Magik source code is compiled down to bytecodes that run on a virtual machine -- in this case the Magik Virtual Machine. Throughout the years, GE has invested considerable engineering talent in the support and maintenance of this virtual machine.  At the same time vast energy and resources have been invested in the Java Virtual Machine. The question for GE has been whether to continue to make that investment on its own or to leverage massive effort provided by the Java community? Utilizing the Java Virtual Machine instead of maintaining its own virtual machine would give GE more opportunity to focus on application solutions.   At last count, there are dozens, perhaps hundreds of examples of programming languages that have been hosted atop the Java Virtual Machine.  Prior to the release of Java 7, that effort, although certainly possible, was generally less than optimal for languages like Magik because of its dynamic nature.  Java, as a statically typed language had little use for this capability.  In the quest to be a more universal virtual machine, Java 7, via JSR-292, introduced a new bytecode called invokedynamic.  In short, invokedynamic affords a more flexible method call mechanism needed by dynamic languages like Magik. With this new capability GE Energy has succeeded in hosting their Magik environment on top of the Java Virtual Machine.  So you may ask, why would GE wish to do such a thing?  The benefits are many: Competitors to GE Energy claimed that the Magik environment was proprietary.  By utilizing the Java Virtual Machine, that argument gets put to bed.  JVM development is done in open source, where contributions are made world-wide by all types of organizations and individuals. The unprecedented wealth of class libraries and applications written for the Java platform are now opened up to Magik/JVM platform as first class citizens. In addition, the Magik/JVM solution vastly increases the developer pool to include the 9 million Java developers -- the largest developer community on the planet. Applications running on the JVM showed substantial performance gains, in some cases as much as a 5x speed up over the original Magik platform. Legacy Magik applications can still run on the original platform.  They can be seamlessly migrated to run on the JVM by simply recompiling the source code. GE can now leverage the huge Java community.  Undeniably the best virtual machine ever created, hundreds if not thousands of world class developers continually improve, poke, prod and scrutinize all aspects of the Java platform.  As enhancements are made, GE automatically gains access to these. As Magik has little in the way of support for multi-threading, GE will benefit from current and future Java offerings (e.g. lambda expressions) that aim to further facilitate multi-core/multi-threaded application development. As the JVM is available for many more platforms, it broadens the reach of Magik, including the potential to run on a class devices never envisioned just a few short years ago.  For example, Java SE compatible runtime environments are available for popular embedded ARM/Intel/PowerPC configurations that could theoretically host this software too. As compared to other JVM language projects, the Magik integration differs in that it represents a serious commercial entity betting a sizable part of its business on the success of this effort.  Expect to see announcements not only from General Electric, but other organizations as they realize the benefits of utilizing the Java Virtual Machine.

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• Best way to store a large amount of game objects and update the ones onscreen

  - by user3002473

  Good afternoon guys! I'm a young beginner game developer working on my first large scale game project and I've run into a situation where I'm not quite sure what the best solution may be (if there is a lone solution). The question may be vague (if anyone can think of a better title after having read the question, please edit it) or broad but I'm not quite sure what to do and I thought it would help just to discuss the problem with people more educated in the field. Before we get started, here are some of the questions I've looked at for help in the past: Best way to keep track of game objects Elegant way to simulate large amounts of entities within a game world What is the most efficient container to store dynamic game objects in? I've also read articles about different data structures commonly used in games to store game objects such as this one about slot maps, but none of them are really what I'm looking for. Also, if it helps at all I'm using Python 3 to design the game. It has to be Python 3, if I could I would use C++ or Unityscript or something else, but I'm restricted to having to use Python 3. My game will be a form of side scroller shooter game. In said game the player will traverse large rooms with large amounts of enemies and other game objects to update (think some of the larger areas in Cave Story or Iji). The player obviously can't see the entire room all at once, so there is a viewport that follows the player around and renders only a selection of the room and the game objects that it contains. This is not a foreign concept. The part that's getting me confused has to do with how certain game objects are updated. Some of them are to be updated constantly, regardless of whether or not they can be seen. Other objects however are only to be updated when they are onscreen (for example, an enemy would only be updated to react to the player when it is onscreen or when it is in a certain range of the screen). Another problem is that game objects have to be easily referable by other game objects; something that happens in the player's update() method may affect another object in the world. Collision detection in games is always a serious problem. I need a way of containing the game objects such that it minimizes the number of cases when testing for collisions against one another. The final problem is that of creating and destroying game objects. I think this problem is pretty self explanatory. To store the game objects then I've considered a number of different methods. The original method I had was to simply store all the objects in a hash table by an id. This method was simple, and decently fast as it allows all the objects to be looked up in O(1) complexity, and also allows them to be deleted fairly easily. Hash collisions would not be a major problem; I wasn't originally planning on using computer generated ids to store the game objects I was going to rely on them all using ids given to them by the game designer (such names would be strings like 'Player' or 'EnemyWeapon4'), and even if I did use computer generated ids, if I used a decent hashing algorithm then the chances of collisions would be around 1 in 4 billion. The problem with using a hash table however is that it is inefficient in checking to see what objects are in range of the viewport. Considering the fact that certain game objects move (as well as the viewport itself), the only solution I could think of in order to only update objects that are in the viewport would be to iterate through every object in the hash table and check if it is in the viewport or not, updating only the ones that are in the valid area. This would be incredibly slow in scenarios where the amount of game objects exceeds 500, or even 200. The second solution was to store everything in a 2-d list. The world is partitioned up into cells (a tilemap essentially), where each cell or tile is the same size and is square. Each cell would contain a list of the game objects that are currently occupying it (each game object would be inserted into a cell depending on the center of the object's collision mask). A 2-d list would allow me to take the top-left and bottom-right corners of the viewport and easily grab a rectangular area of the grid containing only the cells containing entities that are in valid range to be updated. This method also solves the problem of collision detection; when I take an entity I can find the cell that it is currently in, then check only against entities in it's cell and the 8 cells around it. One problem with this system however is that it prohibits easy lookup of game objects. One solution I had would be to simultaneously keep a hash table that would contain all the positions of the objects in the 2-d list indexed by the id of said object. The major problem with a 2-d list is that it would need to be rebuilt every single game frame (along with the hash table of object positions), which may be a serious detriment to game speed. Both systems have ups and downs and seem to solve some of each other's problems, however using them both together doesn't seem like the best solution either. If anyone has any thoughts, ideas, suggestions, comments, opinions or solutions on new data structures or better implementations of the existing data structures I have in mind, please post, any and all criticism and help is welcome. Thanks in advance! EDIT: Please don't close the question because it has a bad title, I'm just bad with names!

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• How I Work: Staying Productive Whilst Traveling

  - by BuckWoody

  I travel a lot. Not like some folks that are gone every week, mind you, although in the last month I’ve been to: Cambridge, UK; Anchorage, AK; San Jose, CA; Copenhagen, DK, Boston, MA; and I’m currently en-route to Anaheim, CA.  While this many places in a month is a bit unusual for me, I would say I travel frequently. I’ve travelled most of my 28+ years in IT, and at one time was a consultant traveling weekly.   With that much time away from my primary work location, I have to find ways to stay productive. Some might say “just rest – take a nap!” – but I’m not able to do that. For one thing, I’m a very light sleeper and I’ve never slept on a plane - even a 30+ hour trip to New Zealand in Business Class - so that just isn’t option. I also am not always in the plane, of course. There’s the hotel, the taxi/bus/train, the airport and then all that over again when I arrive. Since my regular jobs have many demands, I have to get work done.   Note: No, I’m not always focused on work. I need downtime just like everyone else. Sometimes I just think, watch a movie or listen to tunes – and I give myself permission to do that anytime – sometimes the whole trip. I have too fewheartbeats left in life to only focus on work – it’s just not that important, and neither am I. Some of these tasks are letters to friends and family, or other personal things. What I’m talking about here is a plan, not some task list I have to follow. When I get to the location I’m traveling to, I always build in as much time as I can to ensure I enjoy those sights and the people I’m with. I would find traveling to be a waste if not for that.   The Unrealistic Expectation As I would evaluate the trip I was taking – say a 6-8 hour flight – I would expect to get 10-12 hours of work done. After all, there’s the time at the airport, the taxi and so on, and then of course the time in the air with all of the room, power, internet and everything else I needed to get my work done. I would pile up tasks at home, pack my bags, and head happily to the magical land of the TSA.   Right. On return from the trip, I had accomplished little, had more e-mails and other work that had piled up, and I was tired, hungry, and unorganized. This had to change. So, I decided to do three things: Segment my work Set realistic expectations Plan accordingly  Segmenting By Available Resources The first task was to decide what kind of work I could do in each location – if any. I found that I was dependent on a few things to get work done, such as power, the Internet, and a place to sit down. Before I fly, I take some time at home to get all of the work I’d like to accomplish while away segmented into these areas, and print that out on paper, which goes in my suit-coat pocket along with a mechanical pencil. I print my tickets, and I’m all set for the adventure ahead. Then I simply do each kind of work whenever I’m in that situation. No power There are certain times when I don’t have power available. But not only that, I might not even be able to use most of my electronics. So I now schedule as many phone calls as I can for the taxi/bus/train ride and the airports as I can. I have a paper notebook (Moleskine, of course) and a pencil and I print out any notes or numbers I need prior to the trip. Once I’m airborne or at the airport, I work on my laptop. I check and respond to e-mails, create slides, write code, do architecture, whatever I can.  If I can’t use any electronics, or once the power runs out, I schedule time for reading. I can read at the airport or anywhere, actually, even in-flight or any other transport. I “read with a pencil”, meaning I take a lot of notes, which I liketo put in OneNote, but since in most cases I don’t have power, I use the Moleskine to do that. Speaking of which, sometimes as I’m thinking I come up with new topics, ideas, blog posts, or things to teach in my classes. Once again I take out the notebook and write it down. All of these notes get a check-mark when I get back to the office and transfer the writing to OneNote. I’ve tried those “smart pens” and so on to automate this, but it just never works out. Pencil and paper are just fine. As I mentioned, sometime I just need to think. I’ll do nothing, and let my mind wander, thinking of nothing in particular, or some math problem or science question I’m interested in. My only issue with this is that I communicate tothink, and I don’t want to drive people crazy by being that guy that won’t shut up, so I think in a different way. Power, but no Internet or Phone If I have power but no Internet or phone, I focus on the laptop and the tablet as before, and I also recharge my other gadgets. Power, Internet, Phone and a Place to Work At first I thought that when I arrived at the hotel or event I could get the same amount of work done that I do at the office. Not so. There’s simply too many distractions, things you need, or other issues that allow this. Of course, Ican work on any device, read, think, write or whatever, but I am simply not as productive as I am in my home office. So I plan for about 25-50% as much work getting done in this environment as I think I could really do. I’ve done some measurements, and this holds out to be true almost every time. The key is that I re-set my expectations (and my co-worker’s expectations as well) that this is the case. I use the Out-Of-Office notices to let people know that I’m just not going to be 100% at this time – it’s hard for everyone, but it’s more honest and realistic, and I’d rather they know that – and that I realize that – than to let them think I’m totally available. Because I’m not – I’m traveling. I don’t tend to put too much detail, because after all I don’t necessarily want to let people know when I’m not home :) but I do think it’s important to let people that depend on my know that I’ll get back with them later. I hope this helps you think through your own methodology of staying productive when you travel. Or perhaps you just go offline, and don’t worry about any of this – good for you! That’s completely valid as well.   (Oh, and yes, I wrote this at 35K feet, on Alaska Airlines on a trip. :)  Practice what you preach, Buck.)

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• DBA Best Practices - A Blog Series: Episode 1 - Backups

  - by Argenis

    This blog post is part of the DBA Best Practices series, on which various topics of concern for daily database operations are discussed. Your feedback and comments are very much welcome, so please drop by the comments section and be sure to leave your thoughts on the subject. Morning Coffee When I was a DBA, the first thing I did when I sat down at my desk at work was checking that all backups had completed successfully. It really was more of a ritual, since I had a dual system in place to check for backup completion: 1) the scheduled agent jobs to back up the databases were set to alert the NOC in failure, and 2) I had a script run from a central server every so often to check for any backup failures. Why the redundancy, you might ask. Well, for one I was once bitten by the fact that database mail doesn't work 100% of the time. Potential causes for failure include issues on the SMTP box that relays your server email, firewall problems, DNS issues, etc. And so to be sure that my backups completed fine, I needed to rely on a mechanism other than having the servers do the taking - I needed to interrogate the servers and ask each one if an issue had occurred. This is why I had a script run every so often. Some of you might have monitoring tools in place like Microsoft System Center Operations Manager (SCOM) or similar 3rd party products that would track all these things for you. But at that moment, we had no resort but to write our own Powershell scripts to do it. Now it goes without saying that if you don't have backups in place, you might as well find another career. Your most sacred job as a DBA is to protect the data from a disaster, and only properly safeguarded backups can offer you peace of mind here. "But, we have a cluster...we don't need backups" Sadly I've heard this line more than I would have liked to. You need to understand that a cluster is comprised of shared storage, and that is precisely your single point of failure. A cluster will protect you from an issue at the Operating System level, and also under an outage of any SQL-related service or dependent devices. But it will most definitely NOT protect you against corruption, nor will it protect you against somebody deleting data from a table - accidentally or otherwise. Backup, fine. How often do I take a backup? The answer to this is something you will hear frequently when working with databases: it depends. What does it depend on? For one, you need to understand how much data your business is willing to lose. This is what's called Recovery Point Objective, or RPO. If you don't know how much data your business is willing to lose, you need to have an honest and realistic conversation about data loss expectations with your customers, internal or external. From my experience, their first answer to the question "how much data loss can you withstand?" will be "zero". In that case, you will need to explain how zero data loss is very difficult and very costly to achieve, even in today's computing environments. Do you want to go ahead and take full backups of all your databases every hour, or even every day? Probably not, because of the impact that taking a full backup can have on a system. That's what differential and transaction log backups are for. Have I answered the question of how often to take a backup? No, and I did that on purpose. You need to think about how much time you have to recover from any event that requires you to restore your databases. This is what's called Recovery Time Objective. Again, if you go ask your customer how long of an outage they can withstand, at first you will get a completely unrealistic number - and that will be your starting point for discussing a solution that is cost effective. The point that I'm trying to get across is that you need to have a plan. This plan needs to be practiced, and tested. Like a football playbook, you need to rehearse the moves you'll perform when the time comes. How often is up to you, and the objective is that you feel better about yourself and the steps you need to follow when emergency strikes. A backup is nothing more than an untested restore Backups are files. Files are prone to corruption. Put those two together and realize how you feel about those backups sitting on that network drive. When was the last time you restored any of those? Restoring your backups on another box - that, by the way, doesn't have to match the specs of your production server - will give you two things: 1) peace of mind, because now you know that your backups are good and 2) a place to offload your consistency checks with DBCC CHECKDB or any of the other DBCC commands like CHECKTABLE or CHECKCATALOG. This is a great strategy for VLDBs that cannot withstand the additional load created by the consistency checks. If you choose to offload your consistency checks to another server though, be sure to run DBCC CHECKDB WITH PHYSICALONLY on the production server, and if you're using SQL Server 2008 R2 SP1 CU4 and above, be sure to enable traceflags 2562 and/or 2549, which will speed up the PHYSICALONLY checks further - you can read more about this enhancement here. Back to the "How Often" question for a second. If you have the disk, and the network latency, and the system resources to do so, why not backup the transaction log often? As in, every 5 minutes, or even less than that? There's not much downside to doing it, as you will have to clear the log with a backup sooner than later, lest you risk running out space on your tlog, or even your drive. The one drawback to this approach is that you will have more files to deal with at restore time, and processing each file will add a bit of extra time to the entire process. But it might be worth that time knowing that you minimized the amount of data lost. Again, test your plan to make sure that it matches your particular needs. Where to back up to? Network share? Locally? SAN volume? This is another topic where everybody has a favorite choice. So, I'll stick to mentioning what I like to do and what I consider to be the best practice in this regard. I like to backup to a SAN volume, i.e., a drive that actually lives in the SAN, and can be easily attached to another server in a pinch, saving you valuable time - you wouldn't need to restore files on the network (slow) or pull out drives out a dead server (been there, done that, it’s also slow!). The key is to have a copy of those backup files made quickly, and, if at all possible, to a remote target on a different datacenter - or even the cloud. There are plenty of solutions out there that can help you put such a solution together. That right there is the first step towards a practical Disaster Recovery plan. But there's much more to DR, and that's material for a different blog post in this series.

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• We've completed the first iteration

  - by CliveT

  There are a lot of features in C# that are implemented by the compiler and not by the underlying platform. One such feature is a lambda expression. Since local variables cannot be accessed once the current method activation finishes, the compiler has to go out of its way to generate a new class which acts as a home for any variable whose lifetime needs to be extended past the activation of the procedure. Take the following example:     Random generator = new Random();     Func func = () = generator.Next(10); In this case, the compiler generates a new class called c_DisplayClass1 which is marked with the CompilerGenerated attribute. [CompilerGenerated] private sealed class c__DisplayClass1 {     // Fields     public Random generator;     // Methods     public int b__0()     {         return this.generator.Next(10);     } } Two quick comments on this: (i)    A display was the means that compilers for languages like Algol recorded the various lexical contours of the nested procedure activations on the stack. I imagine that this is what has led to the name. (ii)    It is a shame that the same attribute is used to mark all compiler generated classes as it makes it hard to figure out what they are being used for. Indeed, you could imagine optimisations that the runtime could perform if it knew that classes corresponded to certain high level concepts. We can see that the local variable generator has been turned into a field in the class, and the body of the lambda expression has been turned into a method of the new class. The code that builds the Func object simply constructs an instance of this class and initialises the fields to their initial values.     c__DisplayClass1 class2 = new c__DisplayClass1();     class2.generator = new Random();     Func func = new Func(class2.b__0); Reflector already contains code to spot this pattern of code and reproduce the form containing the lambda expression, so this is example is correctly decompiled. The use of compiler generated code is even more spectacular in the case of iterators. C# introduced the idea of a method that could automatically store its state between calls, so that it can pick up where it left off. The code can express the logical flow with yield return and yield break denoting places where the method should return a particular value and be prepared to resume.         {             yield return 1;             yield return 2;             yield return 3;         } Of course, there was already a .NET pattern for expressing the idea of returning a sequence of values with the computation proceeding lazily (in the sense that the work for the next value is executed on demand). This is expressed by the IEnumerable interface with its Current property for fetching the current value and the MoveNext method for forcing the computation of the next value. The sequence is terminated when this method returns false. The C# compiler links these two ideas together so that an IEnumerator returning method using the yield keyword causes the compiler to produce the implementation of an Iterator. Take the following piece of code.         IEnumerable GetItems()         {             yield return 1;             yield return 2;             yield return 3;         } The compiler implements this by defining a new class that implements a state machine. This has an integer state that records which yield point we should go to if we are resumed. It also has a field that records the Current value of the enumerator and a field for recording the thread. This latter value is used for optimising the creation of iterator instances. [CompilerGenerated] private sealed class d__0 : IEnumerable, IEnumerable, IEnumerator, IEnumerator, IDisposable {     // Fields     private int 1__state;     private int 2__current;     public Program 4__this;     private int l__initialThreadId; The body gets converted into the code to construct and initialize this new class. private IEnumerable GetItems() {     d__0 d__ = new d__0(-2);     d__.4__this = this;     return d__; } When the class is constructed we set the state, which was passed through as -2 and the current thread. public d__0(int 1__state) {     this.1__state = 1__state;     this.l__initialThreadId = Thread.CurrentThread.ManagedThreadId; } The state needs to be set to 0 to represent a valid enumerator and this is done in the GetEnumerator method which optimises for the usual case where the returned enumerator is only used once. IEnumerator IEnumerable.GetEnumerator() {     if ((Thread.CurrentThread.ManagedThreadId == this.l__initialThreadId)               && (this.1__state == -2))     {         this.1__state = 0;         return this;     } The state machine itself is implemented inside the MoveNext method. private bool MoveNext() {     switch (this.1__state)     {         case 0:             this.1__state = -1;             this.2__current = 1;             this.1__state = 1;             return true;         case 1:             this.1__state = -1;             this.2__current = 2;             this.1__state = 2;             return true;         case 2:             this.1__state = -1;             this.2__current = 3;             this.1__state = 3;             return true;         case 3:             this.1__state = -1;             break;     }     return false; } At each stage, the current value of the state is used to determine how far we got, and then we generate the next value which we return after recording the next state. Finally we return false from the MoveNext to signify the end of the sequence. Of course, that example was really simple. The original method body didn't have any local variables. Any local variables need to live between the calls to MoveNext and so they need to be transformed into fields in much the same way that we did in the case of the lambda expression. More complicated MoveNext methods are required to deal with resources that need to be disposed when the iterator finishes, and sometimes the compiler uses a temporary variable to hold the return value. Why all of this explanation? We've implemented the de-compilation of iterators in the current EAP version of Reflector (7). This contrasts with previous version where all you could do was look at the MoveNext method and try to figure out the control flow. There's a fair amount of things we have to do. We have to spot the use of a CompilerGenerated class which implements the Enumerator pattern. We need to go to the class and figure out the fields corresponding to the local variables. We then need to go to the MoveNext method and try to break it into the various possible states and spot the state transitions. We can then take these pieces and put them back together into an object model that uses yield return to show the transition points. After that Reflector can carry on optimising using its usual optimisations. The pattern matching is currently a little too sensitive to changes in the code generation, and we only do a limited analysis of the MoveNext method to determine use of the compiler generated fields. In some ways, it is a pity that iterators are compiled away and there is no metadata that reflects the original intent. Without it, we are always going to dependent on our knowledge of the compiler's implementation. For example, we have noticed that the Async CTP changes the way that iterators are code generated, so we'll have to do some more work to support that. However, with that warning in place, we seem to do a reasonable job of decompiling the iterators that are built into the framework. Hopefully, the EAP will give us a chance to find examples where we don't spot the pattern correctly or regenerate the wrong code, and we can improve things. Please give it a go, and report any problems.

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• Stumbling Through: Visual Studio 2010 (Part II)

  I would now like to expand a little on what I stumbled through in part I of my Visual Studio 2010 post and touch on a few other features of VS 2010.  Specifically, I want to generate some code based off of an Entity Framework model and tie it up to an actual data source.  Im not going to take the easy way and tie to a SQL Server data source, though, I will tie it to an XML data file instead.  Why?  Well, why not?  This is purely for learning, there are probably much better ways to get strongly-typed classes around XML but it will force us to go down a path less travelled and maybe learn a few things along the way.  Once we get this XML data and the means to interact with it, I will revisit data binding to this data in a WPF form and see if I cant get reading, adding, deleting, and updating working smoothly with minimal code.  To begin, I will use what was learned in the first part of this blog topic and draw out a data model for the MFL (My Football League) - I dont want the NFL to come down and sue me for using their name in this totally football-related article.  The data model looks as follows, with Teams having Players, and Players having a position and statistics for each season they played: Note that when making the associations between these entities, I was given the option to create the foreign key but I only chose to select this option for the association between Player and Position.  The reason for this is that I am picturing the XML that will contain this data to look somewhat like this: <MFL> <Position/> <Position/> <Position/> <Team>     <Player>         <Statistic/>     </Player> </Team> </MFL> Statistic will be under its associated Player node, and Player will be under its associated Team node no need to have an Id to reference it if we know it will always fall under its parent.  Position, however, is more of a lookup value that will not have any hierarchical relationship to the player.  In fact, the Position data itself may be in a completely different xml file (something Id like to play around with), so in any case, a player will need to reference the position by its Id. So now that we have a simple data model laid out, I would like to generate two things based on it:  A class for each entity with properties corresponding to each entity property An IO class with methods to get data for each entity, either all instances, by Id or by parent. Now my experience with code generation in the past has consisted of writing up little apps that use the code dom directly to regenerate code on demand (or using tools like CodeSmith).  Surely, there has got to be a more fun way to do this given that we are using the Entity Framework which already has built-in code generation for SQL Server support.  Lets start with that built-in stuff to give us a base to work off of.  Right click anywhere in the canvas of our model and select Add Code Generation Item: So just adding that code item seemed to do quite a bit towards what I was intending: It apparently generated a class for each entity, but also a whole ton more.  I mean a TON more.  Way too much complicated code was generated now that code is likely to be a black box anyway so it shouldnt matter, but we need to understand how to make this work the way we want it to work, so lets get ready to do some stumbling through that text template (tt) file. When I open the .tt file that was generated, right off the bat I realize there is going to be trouble there is no color coding, no intellisense no nothing!  That is going to make stumbling through more like groping blindly in the dark while handcuffed and hopping on one foot, which was one of the alternate titles I was considering for this blog.  Thankfully, the community comes to my rescue and I wont have to cast my mind back to the glory days of coding in VI (look it up, kids).  Using the Extension Manager (Available under the Tools menu), I did a quick search for tt editor in the Online Gallery and quickly found the Tangible T4 Editor: Downloading and installing this was a breeze, and after doing so I got some color coding and intellisense while editing the tt files.  If you will be doing any customizing of tt files, I highly recommend installing this extension.  Next, well see if that is enough help for us to tweak that tt file to do the kind of code generation that we wantDid you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• How to completely remove a package that didn't install properly?

  - by chtfn

  I recently installed a package from a ppa on Ubuntu 12.04 beta, but apparently it didn't work out, and now it is giving me errors at every update or install I make, even after deactivating the ppa from my sources. This is what I get when I try uninstalling from USC: installArchives() failed: (Reading database ... (Reading database ... 5% (Reading database ... 10% (Reading database ... 15% (Reading database ... 20% (Reading database ... 25% (Reading database ... 30% (Reading database ... 35% (Reading database ... 40% (Reading database ... 45% (Reading database ... 50% (Reading database ... 55% (Reading database ... 60% (Reading database ... 65% (Reading database ... 70% (Reading database ... 75% (Reading database ... 80% (Reading database ... 85% (Reading database ... 90% (Reading database ... 95% (Reading database ... 100% (Reading database ... 295120 files and directories currently installed.) Removing oracle-java7-installer ... update-alternatives: error: unknown argument `cdrom' dpkg: error processing oracle-java7-installer (--remove): subprocess installed pre-removal script returned error exit status 2 No apport report written because MaxReports is reached already Downloading... --2012-04-12 13:13:21-- http://download.oracle.com/otn-pub/java/jdk/7u3-b04/jdk-7u3-linux-i586.tar.gz Rsolution de download.oracle.com (download.oracle.com)... 203.13.161.233, 203.13.161.234 Connexion vers download.oracle.com (download.oracle.com)|203.13.161.233|:80... connect. requte HTTP transmise, en attente de la rponse... 302 Moved Temporarily Emplacement: https://edelivery.oracle.com/otn-pub/java/jdk/7u3-b04/jdk-7u3-linux-i586.tar.gz [suivant] --2012-04-12 13:13:21-- https://edelivery.oracle.com/otn-pub/java/jdk/7u3-b04/jdk-7u3-linux-i586.tar.gz Rsolution de edelivery.oracle.com (edelivery.oracle.com)... 173.223.150.174 Connexion vers edelivery.oracle.com (edelivery.oracle.com)|173.223.150.174|:443... connect. requte HTTP transmise, en attente de la rponse... 302 Moved Temporarily Emplacement: http://download.oracle.com/errors/download-fail-1505220.html [suivant] --2012-04-12 13:13:22-- http://download.oracle.com/errors/download-fail-1505220.html Connexion vers download.oracle.com (download.oracle.com)|203.13.161.233|:80... connect. requte HTTP transmise, en attente de la rponse... 200 OK Longueur: 5307 (5,2K) [text/html] Sauvegarde en : ./jdk-7u3-linux-i586.tar.gz 0K ..... 100% 4,94M=0,001s 2012-04-12 13:13:22 (4,94 MB/s) - ./jdk-7u3-linux-i586.tar.gz sauvegard [5307/5307] Download done. sha256sum mismatch jdk-7u3-linux-i586.tar.gz Oracle JDK 7 is NOT installed. dpkg: error while cleaning up: subprocess installed post-installation script returned error exit status 1 Errors were encountered while processing: oracle-java7-installer Error in function: I also tried "remove completely" from synaptic but it doesn't work either. Thank you for your help in advance!

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• jqGrid - dynamically load different drop down values for different rows depending on another column value

  - by Renso

  Goal: As we all know the jqGrid examples in the demo and the Wiki always refer to static values for drop down boxes. This of course is a personal preference but in dynamic design these values should be populated from the database/xml file, etc, ideally JSON formatted. Can you do this in jqGrid, yes, but with some custom coding which we will briefly show below (refer to some of my other blog entries for a more detailed discussion on this topic). What you CANNOT do in jqGrid, referrign here up and to version 3.8.x, is to load different drop down values for different rows in the jqGrid. Well, not without some trickery, which is what this discussion is about. Issue: Of course the issue is that jqGrid has been designed for high performance and thus I have no issue with them loading a  reference to a single drop down values list for every column. This way if you have 500 rows or one, each row only refers to a single list for that particuolar column. Nice! SO how easy would it be to simply traverse the grid once loaded on gridComplete or loadComplete and simply load the select tag's options from scratch, via ajax, from memory variable, hard coded etc? Impossible! Since their is no embedded SELECT tag within each cell containing the drop down values (remeber it only has a reference to that list in memory), all you will see when you inspect the cell prior to clicking on it, or even before and on beforeEditCell, is an empty <TD></TD>. When trying to load that list via a click event on that cell will temporarily load the list but jqGrid's last internal callback event will remove it and replace it with the old one, and you are back to square one. Solution: Yes, after spending a few hours on this found a solution to the problem that does not require any updates to jqGrid source code, thank GOD! Before we get into the coding details, the solution here can of course be customized to suite your specific needs, this one loads the entire drop down list that would be needed across all rows once into global variable. I then parse this object that contains all the properties I need to filter the rows depending on which ones I want the user to see based off of another cell value in that row. This only happens when clicking the cell, so no performance penalty. You may of course to load it via ajax when the user clicks the cell, but I found it more effecient to load the entire list as part of jqGrid's normal editoptions: { multiple: false, value: listingStatus } colModel options which again keeps only a reference to the sinlge list, no duplciation. Lets get into the meat and potatoes of it.         var acctId = $('#Id').val();         var data = $.ajax({ url: $('#ajaxGetAllMaterialsTrackingLookupDataUrl').val(), data: { accountId: acctId }, dataType: 'json', async: false, success: function(data, result) { if (!result) alert('Failure to retrieve the Alert related lookup data.'); } }).responseText;         var lookupData = eval('(' + data + ')');         var listingCategory = lookupData.ListingCategory;         var listingStatus = lookupData.ListingStatus;         var catList = '{';         $(lookupData.ListingCategory).each(function() {             catList += this.Id + ':"' + this.Name + '",';         });         catList += '}';         var lastsel;         var ignoreAlert = true;         $(item)         .jqGrid({             url: listURL,             postData: '',             datatype: "local",             colNames: ['Id', 'Name', 'Commission<br />Rep', 'Business<br />Group', 'Order<br />Date', 'Edit', 'TBD', 'Month', 'Year', 'Week', 'Product', 'Product<br />Type', 'Online/<br />Magazine', 'Materials', 'Special<br />Placement', 'Logo', 'Image', 'Text', 'Contact<br />Info', 'Everthing<br />In', 'Category', 'Status'],             colModel: [                 { name: 'Id', index: 'Id', hidden: true, hidedlg: true },                 { name: 'AccountName', index: 'AccountName', align: "left", resizable: true, search: true, width: 100 },                 { name: 'OnlineName', index: 'OnlineName', align: 'left', sortable: false, width: 80 },                 { name: 'ListingCategoryName', index: 'ListingCategoryName', width: 85, editable: true, hidden: false, edittype: "select", editoptions: { multiple: false, value: eval('(' + catList + ')') }, editrules: { required: false }, formatoptions: { disabled: false} }             ],             jsonReader: {                 root: "List",                 page: "CurrentPage",                 total: "TotalPages",                 records: "TotalRecords",                 userdata: "Errors",                 repeatitems: false,                 id: "0"             },             rowNum: $rows,             rowList: [10, 20, 50, 200, 500, 1000, 2000],             imgpath: jQueryImageRoot,             pager: $(item + 'Pager'),             shrinkToFit: true,             width: 1455,             recordtext: 'Traffic lines',             sortname: 'OrderDate',             viewrecords: true,             sortorder: "asc",             altRows: true,             cellEdit: true,             cellsubmit: "remote",             cellurl: editURL + '?rows=' + $rows + '&page=1',             loadComplete: function() {               },             gridComplete: function() {             },             loadError: function(xhr, st, err) {             },             afterEditCell: function(rowid, cellname, value, iRow, iCol) {                 var select = $(item).find('td.edit-cell select');                 $(item).find('td.edit-cell select option').each(function() {                     var option = $(this);                     var optionId = $(this).val();                     $(lookupData.ListingCategory).each(function() {                         if (this.Id == optionId) {                                                       if (this.OnlineName != $(item).getCell(rowid, 'OnlineName')) {                                 option.remove();                                 return false;                             }                         }                     });                 });             },             search: true,             searchdata: {},             caption: "List of all Traffic lines",             editurl: editURL + '?rows=' + $rows + '&page=1',             hiddengrid: hideGrid   Here is the JSON data returned via the ajax call during the jqGrid function call above (NOTE it must be { async: false}: {"ListingCategory":[{"Id":29,"Name":"Document Imaging & Management","OnlineName":"RF Globalnet"} ,{"Id":1,"Name":"Ancillary Department Hardware","OnlineName":"Healthcare Technology Online"} ,{"Id":2,"Name":"Asset Tracking","OnlineName":"Healthcare Technology Online"} ,{"Id":3,"Name":"Asset Tracking","OnlineName":"Healthcare Technology Online"} ,{"Id":4,"Name":"Asset Tracking","OnlineName":"Healthcare Technology Online"} ,{"Id":5,"Name":"Document Imaging & Management","OnlineName":"Healthcare Technology Online"} ,{"Id":6,"Name":"Document Imaging & Management","OnlineName":"Healthcare Technology Online"} ,{"Id":7,"Name":"EMR/EHR Software","OnlineName":"Healthcare Technology Online"}]} I only need the Id and Name for the drop down list, but the third column in the JSON object is important, it is the only that I match up with the OnlineName in the jqGrid column, and then in the loop during afterEditCell simply remove the ones I don't want the user to see. That's it!

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• DBA Best Practices - A Blog Series: Episode 1 - Backups

  - by Argenis

    This blog post is part of the DBA Best Practices series, on which various topics of concern for daily database operations are discussed. Your feedback and comments are very much welcome, so please drop by the comments section and be sure to leave your thoughts on the subject. Morning Coffee When I was a DBA, the first thing I did when I sat down at my desk at work was checking that all backups have completed successfully. It really was more of a ritual, since I had a dual system in place to check for backup completion: 1) the scheduled agent jobs to back up the databases were set to alert the NOC in failure, and 2) I had a script run from a central server every so often to check for any backup failures. Why the redundancy, you might ask. Well, for one I was once bitten by the fact that database mail doesn't work 100% of the time. Potential causes for failure include issues on the SMTP box that relays your server email, firewall problems, DNS issues, etc. And so to be sure that my backups completed fine, I needed to rely on a mechanism other than having the servers do the taking - I needed to interrogate the servers and ask each one if an issue had occurred. This is why I had a script run every so often. Some of you might have monitoring tools in place like Microsoft System Center Operations Manager (SCOM) or similar 3rd party products that would track all these things for you. But at that moment, we had no resort but to write our own Powershell scripts to do it. Now it goes without saying that if you don't have backups in place, you might as well find another career. Your most sacred job as a DBA is to protect the data from a disaster, and only properly safeguarded backups can offer you peace of mind here. "But, we have a cluster...we don't need backups" Sadly I've heard this line more than I would have liked to. You need to understand that a cluster is comprised of shared storage, and that is precisely your single point of failure. A cluster will protect you from an issue at the Operating System level, and also under an outage of any SQL-related service or dependent devices. But it will most definitely NOT protect you against corruption, nor will it protect you against somebody deleting data from a table - accidentally or otherwise. Backup, fine. How often do I take a backup? The answer to this is something you will hear frequently when working with databases: it depends. What does it depend on? For one, you need to understand how much data your business is willing to lose. This is what's called Recovery Point Objective, or RPO. If you don't know how much data your business is willing to lose, you need to have an honest and realistic conversation about data loss expectations with your customers, internal or external. From my experience, their first answer to the question "how much data loss can you withstand?" will be "zero". In that case, you will need to explain how zero data loss is very difficult and very costly to achieve, even in today's computing environments. Do you want to go ahead and take full backups of all your databases every hour, or even every day? Probably not, because of the impact that taking a full backup can have on a system. That's what differential and transaction log backups are for. Have I answered the question of how often to take a backup? No, and I did that on purpose. You need to think about how much time you have to recover from any event that requires you to restore your databases. This is what's called Recovery Time Objective. Again, if you go ask your customer how long of an outage they can withstand, at first you will get a completely unrealistic number - and that will be your starting point for discussing a solution that is cost effective. The point that I'm trying to get across is that you need to have a plan. This plan needs to be practiced, and tested. Like a football playbook, you need to rehearse the moves you'll perform when the time comes. How often is up to you, and the objective is that you feel better about yourself and the steps you need to follow when emergency strikes. A backup is nothing more than an untested restore Backups are files. Files are prone to corruption. Put those two together and realize how you feel about those backups sitting on that network drive. When was the last time you restored any of those? Restoring your backups on another box - that, by the way, doesn't have to match the specs of your production server - will give you two things: 1) peace of mind, because now you know that your backups are good and 2) a place to offload your consistency checks with DBCC CHECKDB or any of the other DBCC commands like CHECKTABLE or CHECKCATALOG. This is a great strategy for VLDBs that cannot withstand the additional load created by the consistency checks. If you choose to offload your consistency checks to another server though, be sure to run DBCC CHECKDB WITH PHYSICALONLY on the production server, and if you're using SQL Server 2008 R2 SP1 CU4 and above, be sure to enable traceflags 2562 and/or 2549, which will speed up the PHYSICALONLY checks further - you can read more about this enhancement here. Back to the "How Often" question for a second. If you have the disk, and the network latency, and the system resources to do so, why not backup the transaction log often? As in, every 5 minutes, or even less than that? There's not much downside to doing it, as you will have to clear the log with a backup sooner than later, lest you risk running out space on your tlog, or even your drive. The one drawback to this approach is that you will have more files to deal with at restore time, and processing each file will add a bit of extra time to the entire process. But it might be worth that time knowing that you minimized the amount of data lost. Again, test your plan to make sure that it matches your particular needs. Where to back up to? Network share? Locally? SAN volume? This is another topic where everybody has a favorite choice. So, I'll stick to mentioning what I like to do and what I consider to be the best practice in this regard. I like to backup to a SAN volume, i.e., a drive that actually lives in the SAN, and can be easily attached to another server in a pinch, saving you valuable time - you wouldn't need to restore files on the network (slow) or pull out drives out a dead server (been there, done that, it’s also slow!). The key is to have a copy of those backup files made quickly, and, if at all possible, to a remote target on a different datacenter - or even the cloud. There are plenty of solutions out there that can help you put such a solution together. That right there is the first step towards a practical Disaster Recovery plan. But there's much more to DR, and that's material for a different blog post in this series.

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• Friday Tips #3

  - by Chris Kawalek

  Even though yesterday was Thanksgiving here in the US, we still have a Friday tip for those of you around your computers today. In fact, we have two! The first one came in last week via our #AskOracleVirtualization Twitter hashtag. The tweet has disappeared into the ether now, but we remember the gist, so here it is: Question: Will there be an Oracle Virtual Desktop Client for Android? Answer by our desktop virtualization product development team: We are looking at Android as a supported platform for future releases. Question: How can I make a Sun Ray Client automatically connect to a virtual machine? Answer by Rick Butland, Principal Sales Consultant, Oracle Desktop Virtualization: Someone recently asked how they can assign VM’s to specific Sun Ray Desktop Units (“DTU’s”) without any user interfaction being required, without the “Desktop Selector” being displayed, or any User Directory.  That is, they wanted each Sun Ray to power on and immediately connect to a pre-assigned Solaris VM.   This can be achieved by using “tokens” for user assignment – that is, the tokens found on Smart Cards, DTU’s, or OVDC clients can be used in place of user credentials.  Note, however, that mixing “token-only” assignments and “User Directories” in the same VDI Center won’t work.   Much of this procedure is covered in the documentation, particularly here. But it can useful to have everything in one place, “cookbook-style”:  1. Create the “token-only” directory type: From the VDI administration interface, select:  “Settings”, “Company”, “New”, select the “None” radio button, and click “Next.” Enter a name for the new “Company”, and click “Next”, then “Finish.” 2. Create Desktop Providers, Pools, and VM’s as appropriate. 3. Access the Sun Ray administration interface at http://servername:1660 and login using “root” credentials, and access the token-id’s you wish to use for assignment.  If you’re using DTU tokens rather than Smart Card tokens, these can be found under the “Tokens” tab, and “Search-ing” using the “Currently Used Tokens” tab.  DTU’s can be identified by the prefix “psuedo.”   For example: 4. Copy/paste this token into the VDI administrative interface, by selecting “Users”, “New”, and pasting in the token ID, and click “OK” - for example: 5. Assign the token (DTU) to a desktop, that is, in the VDI Admin Gui, select “Pool”, “Desktop”, select the VM, and click "Assign" and select the token you want, for example: In addition to assigning tokens to desktops, you'll need to bypass the login screen.  To do this, you need to do two things:  1.  Disable VDI client authentication with:  /opt/SUNWvda/sbin/vda settings-setprops -p clientauthentication=Disabled 2. Disable the VDI login screen – to do this,  add a kiosk argument of "-n" to the Sun Ray kiosk arguments screen.   You set this on the Sun Ray administration page - "Advanced", "Kiosk Mode", "Edit", and add the “-n” option to the arguments screen, for example: 3.  Restart both the Sun Ray and VDI services: # /opt/SUNWut/sbin/utstart –c # /opt/SUNWvda/sbin/vda-service restart Remember, if you have a question for us, please post on Twitter with our hashtag (again, it's #AskOracleVirtualization), and we'll try to answer it if we can. See you next time!

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• Node Serialization in NetBeans Platform 7.0

  - by Geertjan

  Node serialization makes sense when you're not interested in the data (since that should be serialized to a database), but in the state of the application. For example, when the application restarts, you want the last selected node to automatically be selected again. That's not the kind of information you'll want to store in a database, hence node serialization is not about data serialization but about application state serialization. I've written about this topic in October 2008, here and here, but want to show how to do this again, using NetBeans Platform 7.0. Somewhere I remember reading that this can't be done anymore and that's typically the best motivation for me, i.e., to prove that it can be done after all. Anyway, in a standard POJO/Node/BeanTreeView scenario, do the following: Remove the "@ConvertAsProperties" annotation at the top of the class, which you'll find there if you used the Window Component wizard. We're not going to use property-file based serialization, but plain old java.io.Serializable  instead. In the TopComponent, assuming it is named "UserExplorerTopComponent", typically at the end of the file, add the following: @Override public Object writeReplace() { //We want to work with one selected item only //and thanks to BeanTreeView.setSelectionMode, //only one node can be selected anyway: Handle handle = NodeOp.toHandles(em.getSelectedNodes())[0]; return new ResolvableHelper(handle); } public final static class ResolvableHelper implements Serializable { private static final long serialVersionUID = 1L; public Handle selectedHandle; private ResolvableHelper(Handle selectedHandle) { this.selectedHandle = selectedHandle; } public Object readResolve() { WindowManager.getDefault().invokeWhenUIReady(new Runnable() { @Override public void run() { try { //Get the TopComponent: UserExplorerTopComponent tc = (UserExplorerTopComponent) WindowManager.getDefault().findTopComponent("UserExplorerTopComponent"); //Get the display text to search for: String selectedDisplayName = selectedHandle.getNode().getDisplayName(); //Get the root, which is the parent of the node we want: Node root = tc.getExplorerManager().getRootContext(); //Find the node, by passing in the root with the display text: Node selectedNode = NodeOp.findPath(root, new String[]{selectedDisplayName}); //Set the explorer manager's selected node: tc.getExplorerManager().setSelectedNodes(new Node[]{selectedNode}); } catch (PropertyVetoException ex) { Exceptions.printStackTrace(ex); } catch (IOException ex) { Exceptions.printStackTrace(ex); } } }); return null; } } Assuming you have a node named "UserNode" for a type named "User" containing a property named "type", add the bits in bold below to your "UserNode": public class UserNode extends AbstractNode implements Serializable { static final long serialVersionUID = 1L; public UserNode(User key) { super(Children.LEAF); setName(key.getType()); } @Override public Handle getHandle() { return new CustomHandle(this, getName()); } public class CustomHandle implements Node.Handle { static final long serialVersionUID = 1L; private AbstractNode node = null; private final String searchString; public CustomHandle(AbstractNode node, String searchString) { this.node = node; this.searchString = searchString; } @Override public Node getNode() { node.setName(searchString); return node; } } } Run the application and select one of the user nodes. Close the application. Start it up again. The user node is not automatically selected, in fact, the window does not open, and you will see this in the output: Caused: java.io.InvalidClassException: org.serialization.sample.UserNode; no valid constructor Read this article and then you'll understand the need for this class: public class BaseNode extends AbstractNode { public BaseNode() { super(Children.LEAF); } public BaseNode(Children kids) { super(kids); } public BaseNode(Children kids, Lookup lkp) { super(kids, lkp); } } Now, instead of extending AbstractNode in your UserNode, extend BaseNode. Then the first non-serializable superclass of the UserNode has an explicitly declared no-args constructor, Do the same as the above for each node in the hierarchy that needs to be serialized. If you have multiple nodes needing serialization, you can share the "CustomHandle" inner class above between all the other nodes, while all the other nodes will also need to extend BaseNode (or provide their own non-serializable super class that explicitly declares a no-args constructor). Now, when I run the application, I select a node, then I close the application, restart it, and the previously selected node is automatically selected when the application has restarted.

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