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• Using Resources the Right Way

  - by BuckWoody

  It’s an interesting time in computing technology. At one point there was a dearth of information available for solving a given problem, or educating ourselves on broader topics so that we can solve problems in the future. With dozens, perhaps hundreds or thousands of web sites and content available (for free, in many cases) from vendors, peers, even colleges and universities, it seems like there is actually too much information. Who has the time to absorb all this information and training? Even if you had the inclination, where to start? In fact, it seems so overwhelming that I often hear people saying that they can’t find the training they need, or that vendor X or Y “doesn’t help their users”. On questioning these folks, however, I often find that they – and sometimes I - haven’t put in the effort to learn what resources we have. That’s where blogs, like this one, can help. If you follow a blog, either by checking it often or perhaps subscribing to the Really Simple Syndication (RSS) feed, you’ll be able to spread out the search or create a mental filter for the information you need. But it’s not enough just read a blog or a web page. The creators need real feedback – what doesn’t work, and what does. Yes, you’re allowed to tell a vendor or writer “This helped me because…” so that you reinforce the positives. To be sure, bring up what doesn’t work as well –  that’s fine. But be specific, and be constructive. You’d be surprised at how much it matters. I know for a fact at Microsoft we listen – there is a real live person that reads your comments. I’m sure this is true of other vendors, and I also know that most blog authors – yours truly most especially – wants to know what you think.   In this blog entry I’d to call your attention to three resources you have at your disposal, and how you can use them to help. I’ll try to bring up things like this from time to time that I find useful, and cover in them in more depth like this. Think of this as a synopsis of a longer set of resources that you can use to filter whether you want to research further, bookmark, or forward on to a circle of friends where you think it might help them.   Data Driven Design Concepts http://msdn.microsoft.com/en-us/library/windowsazure/jj156154 I’ll start with a great site that walks you through the process of designing a solution from a data-first perspective. As you know, I believe all computing is merely re-arranging data. If you follow that logic as well, you’ll realize that whenever you create a solution, you should start at the data-end of the application. This resource helps you do that. Even if you don’t use the specific technologies the instructions use, the concepts hold for almost any other technology that deals with data. This should be a definite bookmark for a developer, DBA, or Data Architect. When I mentioned my admiration for this resource here at Microsoft, the team that created it contacted me and asked if I’d share an e-mail address to my readers so that you can comment on it. You’re guaranteed to be heard – you can suggest changes, talk about how useful – or not – it is, and so on. Here’s that address:  [email protected]   End-to-End Example of a complete Hybrid Application – with Live Demo https://azurestocktrader.cloudapp.net/Default.aspx I learn by example. I also like having ready-made, live, functional demos that show the completed solution at work. If you’ve ever wanted to learn how a complex, complete, hybrid application that bridges on-premises systems with cloud-based databases, code, functions and more, this is it. It’s a stock-trading simulator, and you can get everything from the design to the code itself, or you can just play with the application. It’s running on Windows Azure, the actual production servers we use for everything else. Using a Cloud-Based Service https://azureconfigweb.cloudapp.net/Default.aspx Along with that stock-trading application, you have a full demonstration and usable code sample of a web-based service available. If you’re a developer, this is a style of code you need to understand for everything from iPhone development to a full Service-Oriented Architecture (SOA) environment. So check out these resources. I’ll post more from time to time as I run across them. Hopefully they’ll be as useful to you as they are to me. Oh, and if you have a comment on any of the resources, let them know. And if you have any comments about these or any of my entries, feel free to post away. To quote a famous TV Show: “Hello Seattle – I’m listening…”

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• Performance triage

  - by Dave

  Folks often ask me how to approach a suspected performance issue. My personal strategy is informed by the fact that I work on concurrency issues. (When you have a hammer everything looks like a nail, but I'll try to keep this general). A good starting point is to ask yourself if the observed performance matches your expectations. Expectations might be derived from known system performance limits, prototypes, and other software or environments that are comparable to your particular system-under-test. Some simple comparisons and microbenchmarks can be useful at this stage. It's also useful to write some very simple programs to validate some of the reported or expected system limits. Can that disk controller really tolerate and sustain 500 reads per second? To reduce the number of confounding factors it's better to try to answer that question with a very simple targeted program. And finally, nothing beats having familiarity with the technologies that underlying your particular layer. On the topic of confounding factors, as our technology stacks become deeper and less transparent, we often find our own technology working against us in some unexpected way to choke performance rather than simply running into some fundamental system limit. A good example is the warm-up time needed by just-in-time compilers in Java Virtual Machines. I won't delve too far into that particular hole except to say that it's rare to find good benchmarks and methodology for java code. Another example is power management on x86. Power management is great, but it can take a while for the CPUs to throttle up from low(er) frequencies to full throttle. And while I love "turbo" mode, it makes benchmarking applications with multiple threads a chore as you have to remember to turn it off and then back on otherwise short single-threaded runs may look abnormally fast compared to runs with higher thread counts. In general for performance characterization I disable turbo mode and fix the power governor at "performance" state. Another source of complexity is the scheduler, which I've discussed in prior blog entries. Lets say I have a running application and I want to better understand its behavior and performance. We'll presume it's warmed up, is under load, and is an execution mode representative of what we think the norm would be. It should be in steady-state, if a steady-state mode even exists. On Solaris the very first thing I'll do is take a set of "pstack" samples. Pstack briefly stops the process and walks each of the stacks, reporting symbolic information (if available) for each frame. For Java, pstack has been augmented to understand java frames, and even report inlining. A few pstack samples can provide powerful insight into what's actually going on inside the program. You'll be able to see calling patterns, which threads are blocked on what system calls or synchronization constructs, memory allocation, etc. If your code is CPU-bound then you'll get a good sense where the cycles are being spent. (I should caution that normal C/C++ inlining can diffuse an otherwise "hot" method into other methods. This is a rare instance where pstack sampling might not immediately point to the key problem). At this point you'll need to reconcile what you're seeing with pstack and your mental model of what you think the program should be doing. They're often rather different. And generally if there's a key performance issue, you'll spot it with a moderate number of samples. I'll also use OS-level observability tools to lock for the existence of bottlenecks where threads contend for locks; other situations where threads are blocked; and the distribution of threads over the system. On Solaris some good tools are mpstat and too a lesser degree, vmstat. Try running "mpstat -a 5" in one window while the application program runs concurrently. One key measure is the voluntary context switch rate "vctx" or "csw" which reflects threads descheduling themselves. It's also good to look at the user; system; and idle CPU percentages. This can give a broad but useful understanding if your threads are mostly parked or mostly running. For instance if your program makes heavy use of malloc/free, then it might be the case you're contending on the central malloc lock in the default allocator. In that case you'd see malloc calling lock in the stack traces, observe a high csw/vctx rate as threads block for the malloc lock, and your "usr" time would be less than expected. Solaris dtrace is a wonderful and invaluable performance tool as well, but in a sense you have to frame and articulate a meaningful and specific question to get a useful answer, so I tend not to use it for first-order screening of problems. It's also most effective for OS and software-level performance issues as opposed to HW-level issues. For that reason I recommend mpstat & pstack as my the 1st step in performance triage. If some other OS-level issue is evident then it's good to switch to dtrace to drill more deeply into the problem. Only after I've ruled out OS-level issues do I switch to using hardware performance counters to look for architectural impediments.

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• A Knights Tale

  - by Phil Factor

  There are so many lessons to be learned from the story of Knight Capital losing nearly half a billion dollars as a result of a deployment gone wrong. The Knight Capital Group (KCG N) was an American global financial services firm engaging in market making, electronic execution, and institutional sales and trading. According to the recent order (File No.3.15570) against Knight Capital by U.S. Securities and Exchange Commission?, Knight had, for many years used some software which broke up incoming “parent” orders into smaller “child” orders that were then transmitted to various exchanges or trading venues for execution. A tracking ‘cumulative quantity’ function counted the number of ‘child’ orders and stopped the process once the total of child orders matched the ‘parent’ and so the parent order had been completed. Back in the mists of time, some code had been added to it  which was excuted if a particular flag was set. It was called ‘power peg’ and seems to have had a similar design and purpose, but, one guesses, would have shared the same tracking function. This code had been abandoned in 2003, but never deleted. In 2005, The tracking function was moved to an earlier point in the main process. It would seem from the account that, from that point, had that flag ever been set, the old ‘Power Peg’ would have been executed like Godzilla bursting from the ice, making child orders without limit without any tracking function. It wasn’t, presumably because the software that set the flag was removed. In 2012, nearly a decade after ‘Power Peg’ was abandoned, Knight prepared a new module to their software to cope with the imminent Retail Liquidity Program (RLP) for the New York Stock Exchange. By this time, the flag had remained unused and someone made the fateful decision to reuse it, and replace the old ‘power peg’ code with this new RLP code. Had the two actions been done together in a single automated deployment, and the new deployment tested, all would have been well. It wasn’t. To quote… “Beginning on July 27, 2012, Knight deployed the new RLP code in SMARS in stages by placing it on a limited number of servers in SMARS on successive days. During the deployment of the new code, however, one of Knight’s technicians did not copy the new code to one of the eight SMARS computer servers. Knight did not have a second technician review this deployment and no one at Knight realized that the Power Peg code had not been removed from the eighth server, nor the new RLP code added. Knight had no written procedures that required such a review.” (para 15) “On August 1, Knight received orders from broker-dealers whose customers were eligible to participate in the RLP. The seven servers that received the new code processed these orders correctly. However, orders sent with the repurposed flag to the eighth server triggered the defective Power Peg code still present on that server. As a result, this server began sending child orders to certain trading centers for execution. Because the cumulative quantity function had been moved, this server continuously sent child orders, in rapid sequence, for each incoming parent order without regard to the number of share executions Knight had already received from trading centers. Although one part of Knight’s order handling system recognized that the parent orders had been filled, this information was not communicated to SMARS.” (para 16) SMARS routed millions of orders into the market over a 45-minute period, and obtained over 4 million executions in 154 stocks for more than 397 million shares. By the time that Knight stopped sending the orders, Knight had assumed a net long position in 80 stocks of approximately $3.5 billion and a net short position in 74 stocks of approximately $3.15 billion. Knight’s shares dropped more than 20% after traders saw extreme volume spikes in a number of stocks, including preferred shares of Wells Fargo (JWF) and semiconductor company Spansion (CODE). Both stocks, which see roughly 100,000 trade per day, had changed hands more than 4 million times by late morning. Ultimately, Knight lost over $460 million from this wild 45 minutes of trading. Obviously, I’m interested in all this because, at one time, I used to write trading systems for the City of London. Obviously, the US SEC is in a far better position than any of us to work out the failings of Knight’s IT department, and the report makes for painful reading. I can’t help observing, though, that even with the breathtaking mistakes all along the way, that a robust automated deployment process that was ‘all-or-nothing’, and tested from soup to nuts would have prevented the disaster. The report reads like a Greek Tragedy. All the way along one wants to shout ‘No! not that way!’ and ‘Aargh! Don’t do it!’. As the tragedy unfolds, the audience weeps for the players, trapped by a cruel fate. All application development and deployment requires defense in depth. All IT goes wrong occasionally, but if there is a culture of defensive programming throughout, the consequences are usually containable. For financial systems, these defenses are required by statute, and ignored only by the foolish. Knight’s mistakes weren’t made by just one hapless sysadmin, but were progressive errors by an  IT culture spanning at least ten years.  One can spell these out, but I think they’re obvious. One can only hope that the industry studies what happened in detail, learns from the mistakes, and draws the right conclusions.

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• Developing Schema Compare for Oracle (Part 6): 9i Query Performance

  - by Simon Cooper

  All throughout the EAP and beta versions of Schema Compare for Oracle, our main request was support for Oracle 9i. After releasing version 1.0 with support for 10g and 11g, our next step was then to get version 1.1 of SCfO out with support for 9i. However, there were some significant problems that we had to overcome first. This post will concentrate on query execution time. When we first tested SCfO on a 9i server, after accounting for various changes to the data dictionary, we found that database registration was taking a long time. And I mean a looooooong time. The same database that on 10g or 11g would take a couple of minutes to register would be taking upwards of 30 mins on 9i. Obviously, this is not ideal, so a poke around the query execution plans was required. As an example, let's take the table population query - the one that reads ALL_TABLES and joins it with a few other dictionary views to get us back our list of tables. On 10g, this query takes 5.6 seconds. On 9i, it takes 89.47 seconds. The difference in execution plan is even more dramatic - here's the (edited) execution plan on 10g: -------------------------------------------------------------------------------| Id | Operation | Name | Bytes | Cost |-------------------------------------------------------------------------------| 0 | SELECT STATEMENT | | 108K| 939 || 1 | SORT ORDER BY | | 108K| 939 || 2 | NESTED LOOPS OUTER | | 108K| 938 ||* 3 | HASH JOIN RIGHT OUTER | | 103K| 762 || 4 | VIEW | ALL_EXTERNAL_LOCATIONS | 2058 | 3 ||* 20 | HASH JOIN RIGHT OUTER | | 73472 | 759 || 21 | VIEW | ALL_EXTERNAL_TABLES | 2097 | 3 ||* 34 | HASH JOIN RIGHT OUTER | | 39920 | 755 || 35 | VIEW | ALL_MVIEWS | 51 | 7 || 58 | NESTED LOOPS OUTER | | 39104 | 748 || 59 | VIEW | ALL_TABLES | 6704 | 668 || 89 | VIEW PUSHED PREDICATE | ALL_TAB_COMMENTS | 2025 | 5 || 106 | VIEW | ALL_PART_TABLES | 277 | 11 |------------------------------------------------------------------------------- And the same query on 9i: -------------------------------------------------------------------------------| Id | Operation | Name | Bytes | Cost |-------------------------------------------------------------------------------| 0 | SELECT STATEMENT | | 16P| 55G|| 1 | SORT ORDER BY | | 16P| 55G|| 2 | NESTED LOOPS OUTER | | 16P| 862M|| 3 | NESTED LOOPS OUTER | | 5251G| 992K|| 4 | NESTED LOOPS OUTER | | 4243M| 2578 || 5 | NESTED LOOPS OUTER | | 2669K| 1440 ||* 6 | HASH JOIN OUTER | | 398K| 302 || 7 | VIEW | ALL_TABLES | 342K| 276 || 29 | VIEW | ALL_MVIEWS | 51 | 20 ||* 50 | VIEW PUSHED PREDICATE | ALL_TAB_COMMENTS | 2043 | ||* 66 | VIEW PUSHED PREDICATE | ALL_EXTERNAL_TABLES | 1777K| ||* 80 | VIEW PUSHED PREDICATE | ALL_EXTERNAL_LOCATIONS | 1744K| ||* 96 | VIEW | ALL_PART_TABLES | 852K| |------------------------------------------------------------------------------- Have a look at the cost column. 10g's overall query cost is 939, and 9i is 55,000,000,000 (or more precisely, 55,496,472,769). It's also having to process far more data. What on earth could be causing this huge difference in query cost? After trawling through the '10g New Features' documentation, we found item 1.9.2.21. Before 10g, Oracle advised that you do not collect statistics on data dictionary objects. From 10g, it advised that you do collect statistics on the data dictionary; for our queries, Oracle therefore knows what sort of data is in the dictionary tables, and so can generate an efficient execution plan. On 9i, no statistics are present on the system tables, so Oracle has to use the Rule Based Optimizer, which turns most LEFT JOINs into nested loops. If we force 9i to use hash joins, like 10g, we get a much better plan: -------------------------------------------------------------------------------| Id | Operation | Name | Bytes | Cost |-------------------------------------------------------------------------------| 0 | SELECT STATEMENT | | 7587K| 3704 || 1 | SORT ORDER BY | | 7587K| 3704 ||* 2 | HASH JOIN OUTER | | 7587K| 822 ||* 3 | HASH JOIN OUTER | | 5262K| 616 ||* 4 | HASH JOIN OUTER | | 2980K| 465 ||* 5 | HASH JOIN OUTER | | 710K| 432 ||* 6 | HASH JOIN OUTER | | 398K| 302 || 7 | VIEW | ALL_TABLES | 342K| 276 || 29 | VIEW | ALL_MVIEWS | 51 | 20 || 50 | VIEW | ALL_PART_TABLES | 852K| 104 || 78 | VIEW | ALL_TAB_COMMENTS | 2043 | 14 || 93 | VIEW | ALL_EXTERNAL_LOCATIONS | 1744K| 31 || 106 | VIEW | ALL_EXTERNAL_TABLES | 1777K| 28 |------------------------------------------------------------------------------- That's much more like it. This drops the execution time down to 24 seconds. Not as good as 10g, but still an improvement. There are still several problems with this, however. 10g introduced a new join method - a right outer hash join (used in the first execution plan). The 9i query optimizer doesn't have this option available, so forcing a hash join means it has to hash the ALL_TABLES table, and furthermore re-hash it for every hash join in the execution plan; this could be thousands and thousands of rows. And although forcing hash joins somewhat alleviates this problem on our test systems, there's no guarantee that this will improve the execution time on customers' systems; it may even increase the time it takes (say, if all their tables are partitioned, or they've got a lot of materialized views). Ideally, we would want a solution that provides a speedup whatever the input. To try and get some ideas, we asked some oracle performance specialists to see if they had any ideas or tips. Their recommendation was to add a hidden hook into the product that allowed users to specify their own query hints, or even rewrite the queries entirely. However, we would prefer not to take that approach; as well as a lot of new infrastructure & a rewrite of the population code, it would have meant that any users of 9i would have to spend some time optimizing it to get it working on their system before they could use the product. Another approach was needed. All our population queries have a very specific pattern - a base table provides most of the information we need (ALL_TABLES for tables, or ALL_TAB_COLS for columns) and we do a left join to extra subsidiary tables that fill in gaps (for instance, ALL_PART_TABLES for partition information). All the left joins use the same set of columns to join on (typically the object owner & name), so we could re-use the hash information for each join, rather than re-hashing the same columns for every join. To allow us to do this, along with various other performance improvements that could be done for the specific query pattern we were using, we read all the tables individually and do a hash join on the client. Fortunately, this 'pure' algorithmic problem is the kind that can be very well optimized for expected real-world situations; as well as storing row data we're not using in the hash key on disk, we use very specific memory-efficient data structures to store all the information we need. This allows us to achieve a database population time that is as fast as on 10g, and even (in some situations) slightly faster, and a memory overhead of roughly 150 bytes per row of data in the result set (for schemas with 10,000 tables in that means an extra 1.4MB memory being used during population). Next: fun with the 9i dictionary views.

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• How to make creating viewmodels at runtime less painfull

  - by Mr Happy

  I apologize for the long question, it reads a bit as a rant, but I promise it's not! I've summarized my question(s) below In the MVC world, things are straightforward. The Model has state, the View shows the Model, and the Controller does stuff to/with the Model (basically), a controller has no state. To do stuff the Controller has some dependencies on web services, repository, the lot. When you instantiate a controller you care about supplying those dependencies, nothing else. When you execute an action (method on Controller), you use those dependencies to retrieve or update the Model or calling some other domain service. If there's any context, say like some user wants to see the details of a particular item, you pass the Id of that item as parameter to the Action. Nowhere in the Controller is there any reference to any state. So far so good. Enter MVVM. I love WPF, I love data binding. I love frameworks that make data binding to ViewModels even easier (using Caliburn Micro a.t.m.). I feel things are less straightforward in this world though. Let's do the exercise again: the Model has state, the View shows the ViewModel, and the ViewModel does stuff to/with the Model (basically), a ViewModel does have state! (to clarify; maybe it delegates all the properties to one or more Models, but that means it must have a reference to the model one way or another, which is state in itself) To do stuff the ViewModel has some dependencies on web services, repository, the lot. When you instantiate a ViewModel you care about supplying those dependencies, but also the state. And this, ladies and gentlemen, annoys me to no end. Whenever you need to instantiate a ProductDetailsViewModel from the ProductSearchViewModel (from which you called the ProductSearchWebService which in turn returned IEnumerable<ProductDTO>, everybody still with me?), you can do one of these things: call new ProductDetailsViewModel(productDTO, _shoppingCartWebService /* dependcy */);, this is bad, imagine 3 more dependencies, this means the ProductSearchViewModel needs to take on those dependencies as well. Also changing the constructor is painfull. call _myInjectedProductDetailsViewModelFactory.Create().Initialize(productDTO);, the factory is just a Func, they are easily generated by most IoC frameworks. I think this is bad because Init methods are a leaky abstraction. You also can't use the readonly keyword for fields that are set in the Init method. I'm sure there are a few more reasons. call _myInjectedProductDetailsViewModelAbstractFactory.Create(productDTO); So... this is the pattern (abstract factory) that is usually recommended for this type of problem. I though it was genious since it satisfies my craving for static typing, until I actually started using it. The amount of boilerplate code is I think too much (you know, apart from the ridiculous variable names I get use). For each ViewModel that needs runtime parameters you'll get two extra files (factory interface and implementation), and you need to type the non-runtime dependencies like 4 extra times. And each time the dependencies change, you get to change it in the factory as well. It feels like I don't even use an DI container anymore. (I think Castle Windsor has some kind of solution for this [with it's own drawbacks, correct me if I'm wrong]). do something with anonymous types or dictionary. I like my static typing. So, yeah. Mixing state and behavior in this way creates a problem which don't exist at all in MVC. And I feel like there currently isn't a really adequate solution for this problem. Now I'd like to observe some things: People actually use MVVM. So they either don't care about all of the above, or they have some brilliant other solution. I haven't found an indepth example of MVVM with WPF. For example, the NDDD-sample project immensely helped me understand some DDD concepts. I'd really like it if someone could point me in the direction of something similar for MVVM/WPF. Maybe I'm doing MVVM all wrong and I should turn my design upside down. Maybe I shouldn't have this problem at all. Well I know other people have asked the same question so I think I'm not the only one. To summarize Am I correct to conclude that having the ViewModel being an integration point for both state and behavior is the reason for some difficulties with the MVVM pattern as a whole? Is using the abstract factory pattern the only/best way to instantiate a ViewModel in a statically typed way? Is there something like an in depth reference implementation available? Is having a lot of ViewModels with both state/behavior a design smell?

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• YouTube SEO: Video Optimization

  - by Mike Stiles

  SEO optimization is still regarded as one of the primary tools in the digital marketing kit. However and wherever a potential customer is conducting a search, brands want their content to surface in the top results. Makes sense. But without a regular flow of good, relevant content, your SEO opportunities run shallow. We know from several studies video is one of the most engaging forms of content, so why not make sure that in addition to being cool, your videos are helping you win the SEO game? Keywords:-Decide what search phrases make the most sense for your video. Don’t dare use phrases that have nothing to do with the content. You’ll make people mad.-Research those keywords to see how competitive they are. Adjust them so there are still lots of people searching for it, but there are not as many links showing up for it.-Search your potential keywords and phrases to see what comes up. It’s amazing how many people forget to do that. Video Title: -Try to start and/or end with your keyword.-When you search on YouTube, visual action words tend to come up as suggested searches. So try to use action words. Video Description: -Lead with a link to your site (include http://). -Don’t stuff this with your keyword. It leads to bad writing and it won’t work anyway. This is where you convince people to watch, so write for humans. Use some showmanship. -At the end, do a call to action (subscribe, see the whole playlist, visit our social channels, etc.) Video Tags:-Don’t over-tag. 5-10 tags per video is plenty. -If you’re compelled to have more than 10, that means you should probably make more videos specifically targeting all those keywords. Find Linking Pals:-45% of videos are discovered on video sites. But 44% are found through links on blogs and sites.-Write a blog about your video’s content, then link to the video in it. -A good site for finding places to guest blog is myblogguest.com-Once you find good linking partners, they’ll link to your future videos (as long as they’re good and you’re returning the favor). Tap the Power of Similar Videos:-Use Video Reply to associate your video with other topic-related videos. That’s when you make a video responding to or referencing a video made by someone else. Content:-Again, build up a portfolio of videos, not just one that goes after 30 keywords.-Create shorter, sequential videos that pull them deeper into the content and closer to a desired final action.-Organize your video topics separately using Playlists. Playlists show up as a whole in search results like individual videos, so optimize playlists the same as you would for a video. Meta Data:-Too much importance is placed on it. It accounts for only 15% of search success.-YouTube reads Captions or Transcripts to determine what a video is about. If you’re not using them, you’re missing out.-You get the SEO benefit of captions and transcripts whether the viewers has them toggled on or not. Promotion:-This accounts for 25% of search success.-Promote the daylights out of your videos using your social channels and digital assets. Don’t assume it’s going to magically get discovered. -You can pay to promote your video. This could surface it on the YouTube home page, YouTube search results, YouTube related videos, and across the Google content network. Community:-Accounts for 10% of search success.-Make sure your YouTube home page is a fun place to spend time. Carefully pick your featured video, and make sure your Playlists are featured. -Participate in discussions so users will see you’re present. The volume of ratings/comments is as important as the number of views when it comes to where you surface on search. Video Sitemaps:-As with a web site, a video sitemap helps Google quickly index your video.-Google wants to know title, description, play page URL, the URL of the thumbnail image you want, and raw video file location.-Sitemaps are xml files you host or dynamically generate on your site. Once you’ve made your sitemap, sign in and submit it using Google webmaster tools. Just as with the broadcast and cable TV channels, putting a video out there is only step one. You also have to make sure everybody knows it’s there so the largest audience possible can see it. Here’s hoping you get great ratings. @mikestiles

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• Traversing Java Object Arrays [migrated]

  - by Sundi

  Please Help. Program does not read Array rentBooks[] in the for() loop this option is selected when choosing option 2 then option 4 in the menu The Array reads perfectly when reading the items after the setBook() Method import java.io.File; import java.io.FileNotFoundException; import java.util.Scanner; import java.io.*; import java.util.Locale; import java.text.SimpleDateFormat ; class Library { protected static String Author; protected static String Title; SimpleDateFormat PublicationDate; int itemCode; int available = 1; } class Book extends Library { protected static String PublisherName; protected static String Edition; static Book[] rentBooks = new Book[5]; //Book[] rentBooks = new Book[5]; int count = 0; public Book() { String start= "start"; showBook.main(anza); } public void setBook( String Auth, String Titl, String PublishName) { this.Author = Auth; this.Title = Titl; this.PublisherName = PublishName; } public void getBook() { //System.out.println("*************BOOKS*************************"); System.out.println( "\n\nThe Author of the first Book is "+ this.Author ); System.out.println( "The Title of the book is "+ this.Title); System.out.println( "The Publisher of the book is "+ this.PublisherName ); // System.out.println( "The Edition of the book is "+ Edition ); } } class showBook{ static Book[] rentBooks = new Book[5]; static Book[] rentBooks2 = new Book[5]; static int a,b; //for ( a=0; a < 5; a++ ) //rentBooks2[a] = new Book(); public static void main(String[] args) { File file = new File("Book2.txt"); //Book libraryBooks = new Book(); int j; //initialise Array Class Objects for( j = 0; j < 5; j++) { rentBooks[j] = new Book(); } int i = 0; try{ Scanner scanner = new Scanner(file); scanner.useDelimiter(","); String loan=""; int loan2; while( scanner.hasNextLine()) { //Should the Books be Stored in An Array? // At the moment you have separate objects stored in unknown location String Author = scanner.next(); String Title = scanner.next(); String PublisherName = scanner.next(); if ( i < 4) { System.out.println(i); rentBooks[i].setBook(Author, Title, PublisherName); rentBooks[i].getBook(); // MEMBERS SHOWN i++; } public class readBook4{ public static void main(String[] args) { int number =0; System.out.println( "Please select one of the choices below " ); System.out.println( "Select option 1 to list all items in the library "); System.out.println( "Select option 2 to list the items by category"); System.out.println( "Select option 3 to choose item available in the library "); System.out.println( "Select option 7 to exit " ); InputStreamReader isr = new InputStreamReader( System.in); BufferedReader buffer = new BufferedReader( isr); String input = ""; try { input = buffer.readLine(); number = Integer.parseInt(input); //int number = Integer.parseInt( Edition); if ( number == 1 ) { System.out.println( " \nThanks you are reading "+ input); //showStudent.main(args); showPeriodical.main(args); showDVD.main(args); // showBook.main(args); } if ( number == 2 ) { //jht.cls(); int number2; System.out.println( "Please select one of the choices below " ); System.out.println( "Select option 4 to list Books only "); System.out.println( "Select option 5 to list the Periodicals only"); System.out.println( "Select option 6 to list DVDs only"); InputStreamReader isr2 = new InputStreamReader(System.in); BufferedReader buffer2 = new BufferedReader(isr2); String input2 = ""; try { input2 = buffer2.readLine(); buffer.close(); } catch(IOException e) { System.out.println("An input error has occured"); } //System.out.println("Thanks, you are reading" + input2); number2 = Integer.parseInt(input2); if ( number2 == 4 ) { showBook.main(args); } if ( number2 == 5 ) { showPeriodical.main(args); } if ( number2 == 6 ) { showDVD.main(args); } // readBook4.main(args); } if( number == 3 ) { //showBook.main(args); showBook.availableBooks(); showDVD.availableDVD(); showPeriodical.availablePeriodical(); } if ( number == 7 ) { showStudent.main(args); } buffer.close(); } catch( IOException e ) { System.out.println( " An input error has occured "); } //System.out.println( " \nThanks you are reading "+ input); } } } //buffer.close(); scanner.close(); } catch( FileNotFoundException e) { System.out.println("File not Found"); } for ( i=0; i < 5; i++ ) rentBooks[i].getBook(); //ARRAY NOT SHOWN } }

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• This page calls for XML namespace declared with prefix br but no taglibrary exists

  - by Christopher W. Allen-Poole

  I just finished the Netbeans introduction to Hibernate tutorial ( http://netbeans.org/kb/docs/web/hibernate-webapp.html#01 ) and I am getting the following error: "This page calls for XML namespace declared with prefix br but no taglibrary exists" Now, I have seen a similar question somewhere else: http://forums.sun.com/thread.jspa?threadID=5430327 but the answer is not listed there. Or, if it is, then I am clearly missing it -- line one of my index.xhtml file reads "http://www.w3.org/1999/xhtml". It also does not explain why, when I reload localhost:8080, the message disappears. Here is my index.xhtml file: <html xmlns="http://www.w3.org/1999/xhtml" xmlns:h="http://java.sun.com/jsf/html" xmlns:ui="http://java.sun.com/jsf/facelets" xmlns:f="http://java.sun.com/jsf/core"> <ui:composition template="./template.xhtml"> <ui:define name="body"> <h:form> <h:commandLink action="#{filmController.previous}" value="Previous #{filmController.pageSize}" rendered="#{filmController.hasPreviousPage}"/> <h:commandLink action="#{filmController.next}" value="Next #{filmController.pageSize}" rendered="#{filmController.hasNextPage}"/> <h:dataTable value="#{filmController.filmTitles}" var="item" border="0" cellpadding="2" cellspacing="0" rowClasses="jsfcrud_odd_row,jsfcrud_even_row" rules="all" style="border:solid 1px"> <h:column> <f:facet name="header"> <h:outputText value="Title"/> </f:facet> <h:outputText value="#{item.title}"/> </h:column> <h:column> <f:facet name="header"> <h:outputText value="Description"/> </f:facet> <h:outputText value="#{item.description}"/> </h:column> <h:column> <f:facet name="header"> <h:outputText value=" "/> </f:facet> <h:commandLink action="#{filmController.prepareView}" value="View"/> </h:column> </h:dataTable> <br/> </h:form> </ui:define> </ui:composition> </html>

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• Python: nonblocking read from stdout of threaded subprocess

  - by sberry2A

  I have a script (worker.py) that prints unbuffered output in the form... 1 2 3 . . . n where n is some constant number of iterations a loop in this script will make. In another script (service_controller.py) I start a number of threads, each of which starts a subprocess using subprocess.Popen(stdout=subprocess.PIPE, ...); Now, in my main thread (service_controller.py) I want to read the output of each thread's worker.py subprocess and use it to calculate an estimate for the time remaining till completion. I have all of the logic working that reads the stdout from worker.py and determines the last printed number. The problem is that I can not figure out how to do this in a non-blocking way. If I read a constant bufsize then each read will end up waiting for the same data from each of the workers. I have tried numerous ways including using fcntl, select + os.read, etc. What is my best option here? I can post my source if needed, but I figured the explanation describes the problem well enough. Thanks for any help here. EDIT Adding sample code I have a worker that starts a subprocess. class WorkerThread(threading.Thread): def __init__(self): self.completed = 0 self.process = None self.lock = threading.RLock() threading.Thread.__init__(self) def run(self): cmd = ["/path/to/script", "arg1", "arg2"] self.process = subprocess.Popen(cmd, stdout=subprocess.PIPE, bufsize=1, shell=False) #flags = fcntl.fcntl(self.process.stdout, fcntl.F_GETFL) #fcntl.fcntl(self.process.stdout.fileno(), fcntl.F_SETFL, flags | os.O_NONBLOCK) def get_completed(self): self.lock.acquire(); fd = select.select([self.process.stdout.fileno()], [], [], 5)[0] if fd: self.data += os.read(fd, 1) try: self.completed = int(self.data.split("\n")[-2]) except IndexError: pass self.lock.release() return self.completed I then have a ThreadManager. class ThreadManager(): def __init__(self): self.pool = [] self.running = [] self.lock = threading.Lock() def clean_pool(self, pool): for worker in [x for x in pool is not x.isAlive()]: worker.join() pool.remove(worker) del worker return pool def run(self, concurrent=5): while len(self.running) + len(self.pool) > 0: self.clean_pool(self.running) n = min(max(concurrent - len(self.running), 0), len(self.pool)) if n > 0: for worker in self.pool[0:n]: worker.start() self.running.extend(self.pool[0:n]) del self.pool[0:n] time.sleep(.01) for worker in self.running + self.pool: worker.join() and some code to run it. threadManager = ThreadManager() for i in xrange(0, 5): threadManager.pool.append(WorkerThread()) threadManager.run() I have stripped out a log of the other code in hopes to try to pinpoint the issue.

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• Removing expired certificates from LDS (new ver of ADAM)

  - by jonthebrewer

  Hi all. This is my situation: We are in the process of replacing a certificate store currently hosted on Sun's iPlanet with Microsoft's Lightweight Directory Services (new version of ADAM with Server 2008). These certificates have been imported into LDS into an application partition (say o=myorg, C=AU). Under this structure I have around 40,000 OU's each one representing a customer under each customers OU are one or more user (iNetOrg) objects (around 60,000 in all). In each user are one or more certificates in the UserCertificate attribute. A combination of in-house written application code and proprietory PKI code reads and publishes these certficates to validate financial transactions. As the LDAP path of the certificates is stored within the customer certificates (and within the application code) and there is zero appetite for changing any of the code, I have had to pick up the iPlanet directory as a whole and dump it in LDS in the same structure. (I will not be using or hosting a Microsoft CA, just implementing an LDAP compliant directory to host these certificates) We have fully tested the application using the data in LDS and everything works fine - here is my dilema and question (finally, phew!) There was no process put in place for removing revoked or expired certificates, consequently the vast majority of the data is completely useless, the system has been running for about 8 years! I have done a quick analysis and I estimate that at least 80% of the data is no longer valid. As I am taking on responsibility for managing the directory I would like to start with a clean directory. Does anyone have any idea how I can cleanup these expired certificates. I am not a highly experienced scripter but have some background in VB. I have been researching the use of CAPICOM and have a feeling this may be able to be used but in exactly what way I am not sure?? I would prefer to write a script that I could specify an expiration date (say any certs that expired prior to 2010) then run against the LDS paritition. This way I can reuse the script periodically to cleanup the directory (as mentioned above - I have no way to adjust the applications that are writing the certs, this is with a third party). Another, less attractive, alternative is to massage the LDIF file (2.7 million lines!) to rip the certs out prior to the import Any help and advice MUCH appreciated. Cheers Jon

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• ADO.NET Data Services Entity Framework request error when property setter is internal

  - by Jim Straatman

  I receive an error message when exposing an ADO.NET Data Service using an Entity Framework data model that contains an entity (called "Case") with an internal setter on a property. If I modify the setter to be public (using the entity designer), the data services works fine. I don’t need the entity "Case" exposed in the data service, so I tried to limit which entities are exposed using SetEntitySetAccessRule. This didn’t work, and service end point fails with the same error. public static void InitializeService(IDataServiceConfiguration config) { config.SetEntitySetAccessRule("User", EntitySetRights.AllRead); } The error message is reported in a browser when the .svc endpoint is called. It is very generic, and reads “Request Error. The server encountered an error processing the request. See server logs for more details.” Unfortunately, there are no entries in the System and Application event logs. I found this stackoverflow question that shows how to configure tracing on the service. After doing so, the following NullReferenceExceptoin error was reported in the trace log. Does anyone know how to avoid this exception when including an entity with an internal setter? Blockquote 131076 3 0 2 MOTOJIM http://msdn.microsoft.com/en-US/library/System.ServiceModel.Diagnostics.TraceHandledException.aspx Handling an exception. 685a2910-19-128703978432492675 System.NullReferenceException, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089 Object reference not set to an instance of an object. at System.Data.Services.Providers.ObjectContextServiceProvider.PopulateMemberMetadata(ResourceType resourceType, MetadataWorkspace workspace, IDictionary2 entitySets, IDictionary2 knownTypes) at System.Data.Services.Providers.ObjectContextServiceProvider.PopulateMetadata(IDictionary2 knownTypes, IDictionary2 entitySets) at System.Data.Services.Providers.BaseServiceProvider.PopulateMetadata() at System.Data.Services.DataService1.CreateProvider(Type dataServiceType, Object dataSourceInstance, DataServiceConfiguration&amp; configuration) at System.Data.Services.DataService1.EnsureProviderAndConfigForRequest() at System.Data.Services.DataService1.ProcessRequestForMessage(Stream messageBody) at SyncInvokeProcessRequestForMessage(Object , Object[] , Object[] ) at System.ServiceModel.Dispatcher.SyncMethodInvoker.Invoke(Object instance, Object[] inputs, Object[]&amp; outputs) at System.ServiceModel.Dispatcher.DispatchOperationRuntime.InvokeBegin(MessageRpc&amp; rpc) at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage5(MessageRpc&amp; rpc) at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage4(MessageRpc&amp; rpc) at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage3(MessageRpc&amp; rpc) at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage2(MessageRpc&amp; rpc) at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage1(MessageRpc&amp; rpc) at System.ServiceModel.Dispatcher.MessageRpc.Process(Boolean isOperationContextSet) </StackTrace> <ExceptionString>System.NullReferenceException: Object reference not set to an instance of an object. at System.Data.Services.Providers.ObjectContextServiceProvider.PopulateMemberMetadata(ResourceType resourceType, MetadataWorkspace workspace, IDictionary2 entitySets, IDictionary2 knownTypes) at System.Data.Services.Providers.ObjectContextServiceProvider.PopulateMetadata(IDictionary2 knownTypes, IDictionary2 entitySets) at System.Data.Services.Providers.BaseServiceProvider.P

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• Detecting 'stealth' web-crawlers

  - by Jacco

  What options are there to detect web-crawlers that do not want to be detected? (I know that listing detection techniques will allow the smart stealth-crawler programmer to make a better spider, but I do not think that we will ever be able to block smart stealth-crawlers anyway, only the ones that make mistakes.) I'm not talking about the nice crawlers such as googlebot and Yahoo! Slurp. I consider a bot nice if it: identifies itself as a bot in the user agent string reads robots.txt (and obeys it) I'm talking about the bad crawlers, hiding behind common user agents, using my bandwidth and never giving me anything in return. There are some trapdoors that can be constructed updated list (thanks Chris, gs): Adding a directory only listed (marked as disallow) in the robots.txt, Adding invisible links (possibly marked as rel="nofollow"?), style="display: none;" on link or parent container placed underneath another element with higher z-index detect who doesn't understand CaPiTaLiSaTioN, detect who tries to post replies but always fail the Captcha. detect GET requests to POST-only resources detect interval between requests detect order of pages requested detect who (consistently) requests https resources over http detect who does not request image file (this in combination with a list of user-agents of known image capable browsers works surprisingly nice) Some traps would be triggered by both 'good' and 'bad' bots. you could combine those with a whitelist: It trigger a trap It request robots.txt? It doest not trigger another trap because it obeyed robots.txt One other important thing here is: Please consider blind people using a screen readers: give people a way to contact you, or solve a (non-image) Captcha to continue browsing. What methods are there to automatically detect the web crawlers trying to mask themselves as normal human visitors. Update The question is not: How do I catch every crawler. The question is: How can I maximize the chance of detecting a crawler. Some spiders are really good, and actually parse and understand html, xhtml, css javascript, VB script etc... I have no illusions: I won't be able to beat them. You would however be surprised how stupid some crawlers are. With the best example of stupidity (in my opinion) being: cast all URLs to lower case before requesting them. And then there is a whole bunch of crawlers that are just 'not good enough' to avoid the various trapdoors.

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• How can I load style resources from a dynamically loaded Silverlight application (XAP)?

  - by Tom

  I've followed Tim Heuer's video for dynamically loading other XAP's (into a 'master' Silverlight application), as well as some other links to tweak the loading of resources and am stuck on the particular issue of loading style resources from within the dynamically loaded XAP (i.e. the contents of Assets\Styles.xaml). When I run the master/hosting applcation, it successfully streams the dynamic XAP and I can read the deployment info etc. and load the assembly parts. However, when I actuall try to create an instance of a form from the Dynamic XAP, it fails with Cannot find a Resource with the Name/Key LayoutRootGridStyle which is in it's Assets\Styles.xaml file (it works if I run it directly so I know it's OK). For some reason these don't show up as application resources - not sure if I've totally got the wrong end of the stick, or am just missing something? Code snippet below (apologies it's a bit messy - just trying to get it working first) ... '' # Here's the code that reads the dynamic XAP from the web server ... '' #... wCli = New WebClient AddHandler wCli.OpenReadCompleted, AddressOf OpenXAPCompleted wCli.OpenReadAsync(New Uri("MyTest.xap", UriKind.Relative)) '' #... '' #Here's the sub that's called when openread is completed '' #... Private Sub OpenXAPCompleted(ByVal sender As Object, ByVal e As System.Net.OpenReadCompletedEventArgs) Dim sManifest As String = New StreamReader(Application.GetResourceStream(New StreamResourceInfo(e.Result, Nothing), New Uri("AppManifest.xaml", UriKind.Relative)).Stream).ReadToEnd Dim deploymentRoot As XElement = XDocument.Parse(sManifest).Root Dim deploymentParts As List(Of XElement) = _ (From assemblyParts In deploymentRoot.Elements().Elements() Select assemblyParts).ToList() Dim oAssembly As Assembly = Nothing For Each xElement As XElement In deploymentParts Dim asmPart As AssemblyPart = New AssemblyPart() Dim source As String = xElement.Attribute("Source").Value Dim sInfo As StreamResourceInfo = Application.GetResourceStream(New StreamResourceInfo(e.Result, "application/binary"), New Uri(source, UriKind.Relative)) If source = "MyTest.dll" Then oAssembly = asmPart.Load(sInfo.Stream) Else asmPart.Load(sInfo.Stream) End If Next Dim t As Type() = oAssembly.GetTypes() Dim AppClass = (From parts In t Where parts.FullName.EndsWith(".App") Select parts).SingleOrDefault() Dim mykeys As Array If Not AppClass Is Nothing Then Dim a As Application = DirectCast(oAssembly.CreateInstance(AppClass.FullName), Application) For Each strKey As String In a.Resources.Keys If Not Application.Current.Resources.Contains(strKey) Then Application.Current.Resources.Add(strKey, a.Resources(strKey)) End If Next End If Dim objectType As Type = oAssembly.GetType("MyTest.MainPage") Dim ouiel = Activator.CreateInstance(objectType) Dim myData As UIElement = DirectCast(ouiel, UIElement) Me.splMain.Children.Add(myData) Me.splMain.UpdateLayout() End Sub '' #... '' # And here's the line that fails with "Cannot find a Resource with the Name/Key LayoutRootGridStyle" '' # ... System.Windows.Application.LoadComponent(Me, New System.Uri("/MyTest;component/MainPage.xaml", System.UriKind.Relative)) '' #... any thoughts?

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• 'NoneType' object has no attribute 'get' error using SQLAlchemy

  - by Az

  I've been trying to map an object to a database using SQLAlchemy but have run into a snag. Version info if handy: [OS: Mac OSX 10.5.8 | Python: 2.6.4 | SQLAlchemy: 0.5.8] The class I'm going to map: class Student(object): def __init__(self, name, id): self.id = id self.name = name self.preferences = collections.defaultdict(set) self.allocated_project = None self.allocated_rank = 0 def __repr__(self): return str(self) def __str__(self): return "%s %s" %(self.id, self.name) Background: Now, I've got a function that reads in the necessary information from a text database into these objects. The function more or less works and I can easily access the information from the objects. Before the SQLAlchemy code runs, the function will read in the necessary info and store it into the Class. There is a dictionary called students which stores this as such: students = {} students[id] = Student(<all the info from the various "reader" functions>) Afterwards, there is an "allocation" algorithm that will allocate projects to student. It does that well enough. The allocated_project remains as None if a student is unsuccessful in getting a project. SQLAlchemy bit: So after all this happens, I'd like to map my object to a database table. Using the documentation, I've used the following code to only map certain bits. I also begin to create a Session. from sqlalchemy import * from sqlalchemy.orm import * engine = create_engine('sqlite:///:memory:', echo=False) metadata = MetaData() students_table = Table('studs', metadata, Column('id', Integer, primary_key=True), Column('name', String) ) metadata.create_all(engine) mapper(Student, students_table) Session = sessionmaker(bind=engine) sesh = Session() Now after that, I was curious to see if I could print out all the students from my students dictionary. for student in students.itervalues(): print student What do I get but an error: Traceback (most recent call last): File "~/FYP_Tests/FYP_Tests.py", line 140, in <module> print student File "/~FYP_Tests/Parties.py", line 30, in __str__ return "%s %s" %(self.id, self.name) File "/opt/local/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages/SQLAlchemy-0.5.8-py2.6.egg/sqlalchemy/orm/attributes.py", line 158, in __get__ return self.impl.get(instance_state(instance), instance_dict(instance)) AttributeError: 'NoneType' object has no attribute 'get' I'm at a loss as to how to resolve this issue, if it is an issue. If more information is required, please ask and I will provide it.

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• What are the reasons why the CPU usage doesn’t go 100% with C# and APM?

  - by Martin

  I have an application which is CPU intensive. When the data is processed on a single thread, the CPU usage goes to 100% for many minutes. So the performance of the application appears to be bound by the CPU. I have multithreaded the logic of the application, which result in an increase of the overall performance. However, the CPU usage hardly goes above 30%-50%. I would expect the CPU (and the many cores) to go to 100% since I process many set of data at the same time. Below is a simplified example of the logic I use to start the threads. When I run this example, the CPU goes to 100% (on an 8/16 cores machine). However, my application which uses the same pattern doesn’t. public class DataExecutionContext { public int Counter { get; set; } // Arrays of data } static void Main(string[] args) { // Load data from the database into the context var contexts = new List<DataExecutionContext>(100); for (int i = 0; i < 100; i++) { contexts.Add(new DataExecutionContext()); } // Data loaded. Start to process. var latch = new CountdownEvent(contexts.Count); var processData = new Action<DataExecutionContext>(c => { // The thread doesn't access data from a DB, file, // network, etc. It reads and write data in RAM only // (in its context). for (int i = 0; i < 100000000; i++) c.Counter++; }); foreach (var context in contexts) { processData.BeginInvoke(context, new AsyncCallback(ar => { latch.Signal(); }), null); } latch.Wait(); } I have reduced the number of locks to the strict minimum (only the latch is locking). The best way I found was to create a context in which a thread can read/write in memory. Contexts are not shared among other threads. The threads can’t access the database, files or network. In other words, I profiled my application and I didn’t find any bottleneck. Why the CPU usage of my application doesn’t go about 50%? Is it the pattern I use? Should I create my own thread instead of using the .Net thread pool? Is there any gotchas? Is there any tool that you could recommend me to find my issue? Thanks!

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• ANTLR: using stringTemplate

  - by Kevin Won

  (I'm a Noob with Antlr)... I'm having difficulties getting my grammar with StringTemplates. Basically I'm trying to write a little DSL. I can get my grammar the way I want (it parses correctly), but I can't get the generation of the target code to work with templates. So here's a snippet of my grammar: grammar Pfig; options { output=template; language=CSharp2; } conf : globalName ; globalName : 'GlobalName:' ID -> localConf(name ={$ID.text}) ; I simplified it quite a bit just to get the essence across. Basically, when the lex/parse comes across `GlobalName: Foo' I want it to spit out text based on the StringTemplate called 'localConf'. Super straightforward. So now, let's fire up the parser in a test app and have it process an input file. // C# processing a file with the lex/parser. // the 'app.pfig' file just has one line that reads 'GlobalName: Bla' using (FileStream fs = File.OpenRead("c:\\app.pfig")) { PfigParser parser = new PfigParser(new CommonTokenStream( new PfigLexer(new ANTLRInputStream(fs)))); using (TextReader tr = File.OpenText("./Pfig.stg")) { parser.TemplateLib = new StringTemplateGroup(tr); } var parseResult = parser.conf(); string code = parseResult.Template.ToString(); // Fail: template is null } I can step through the parser code and see that it correctly identifies my text and applies the stringTemplate correctly. The problem is that since this 'globalName' rule is a subrule of 'conf' it doesn't get executed directly--the method just finds it and returns. But the calling 'Conf' method does not keep the return value from the subrule--it goes to thin air. This means that my resultant template on the last line is null. If I get rid of the 'conf' rule in my grammar and call 'globalName' directly, it will work (since it's the only rule on the stack). But I obviously want more than one rule. I've generated the parser in Java and it does the same thing: // antlr generated parser code public PfigParser.conf_return conf() // throws RecognitionException [1] { PfigParser.conf_return retval = new PfigParser.conf_return(); try { { PushFollow(FOLLOW_globalName_in_conf30); globalName(); // <- it calls globalName() but doesn't keep the return. state.followingStackPointer--; } retval.Stop = input.LT(-1); } // snip It's simple to see I don't get some basic concept with how the Template approach is supposed to work with Antlr. I'm quite sure this is my problem but I'm a loggerheads to know what I'm doing wrong... the examples I've seen don't really show real-world template emission of code.

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• Possible reasons for tellg() failing?

  - by Andreas Bonini

  ifstream::tellg() is returning -13 for a certain file. Basically, I wrote a utility that analyzes some source code; I open all files alphabetically, I start with "Apple.cpp" and it works perfectly.. But when it gets to "Conversion.cpp", always on the same file, after reading one line successfully tellg() returns -13. The code in question is: for (int i = 0; i < files.size(); ++i) { /* For each .cpp and .h file */ TextIFile f(files[i]); while (!f.AtEof()) // When it gets to conversion.cpp (not on the others) // first is always successful, second always fails lines.push_back(f.ReadLine()); The code for AtEof is: bool AtEof() { if (mFile.tellg() < 0) FATAL(format("DEBUG - tellg(): %d") % mFile.tellg()); if (mFile.tellg() >= GetSize()) return true; return false; } After it reads successfully the first line of Conversion.cpp, it always crashes with DEBUG - tellg(): -13. This is the whole TextIFile class (wrote by me, the error may be there): class TextIFile { public: TextIFile(const string& path) : mPath(path), mSize(0) { mFile.open(path.c_str(), std::ios::in); if (!mFile.is_open()) FATAL(format("Cannot open %s: %s") % path.c_str() % strerror(errno)); } string GetPath() const { return mPath; } size_t GetSize() { if (mSize) return mSize; const size_t current_position = mFile.tellg(); mFile.seekg(0, std::ios::end); mSize = mFile.tellg(); mFile.seekg(current_position); return mSize; } bool AtEof() { if (mFile.tellg() < 0) FATAL(format("DEBUG - tellg(): %d") % mFile.tellg()); if (mFile.tellg() >= GetSize()) return true; return false; } string ReadLine() { string ret; getline(mFile, ret); CheckErrors(); return ret; } string ReadWhole() { string ret((std::istreambuf_iterator<char>(mFile)), std::istreambuf_iterator<char>()); CheckErrors(); return ret; } private: void CheckErrors() { if (!mFile.good()) FATAL(format("An error has occured while performing an I/O operation on %s") % mPath); } const string mPath; ifstream mFile; size_t mSize; }; Platform is Visual Studio, 32 bit, Windows. Edit: Works on Linux. Edit: I found the cause: line endings. Both Conversion and Guid and others had \n instead of \r\n. I saved them with \r\n instead and it worked. Still, this is not supposed to happen is it?

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• Android - Getting audio to play through earpiece

  - by Donal Rafferty

  I currently have code that reads a recording in from the devices mic using the AudioRecord class and then playing it back out using the AudioTrack class. My problem is that when I play it out it plays vis the speaker phone. I want it to play out via the ear piece on the device. Here is my code: public class LoopProg extends Activity { boolean isRecording; //currently not used AudioManager am; int count = 0; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); am = (AudioManager) getSystemService(Context.AUDIO_SERVICE); am.setMicrophoneMute(true); while(count <= 1000000){ Record record = new Record(); record.run(); count ++; Log.d("COUNT", "Count is : " + count); } } public class Record extends Thread { static final int bufferSize = 200000; final short[] buffer = new short[bufferSize]; short[] readBuffer = new short[bufferSize]; public void run() { isRecording = true; android.os.Process.setThreadPriority (android.os.Process.THREAD_PRIORITY_URGENT_AUDIO); int buffersize = AudioRecord.getMinBufferSize(11025, AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_16BIT); AudioRecord arec = new AudioRecord(MediaRecorder.AudioSource.MIC, 11025, AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_16BIT, buffersize); AudioTrack atrack = new AudioTrack(AudioManager.STREAM_MUSIC, 11025, AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_16BIT, buffersize, AudioTrack.MODE_STREAM); am.setRouting(AudioManager.MODE_NORMAL,1, AudioManager.STREAM_MUSIC); int ok = am.getRouting(AudioManager.ROUTE_EARPIECE); Log.d("ROUTING", "getRouting = " + ok); setVolumeControlStream(AudioManager.STREAM_VOICE_CALL); //am.setSpeakerphoneOn(true); Log.d("SPEAKERPHONE", "Is speakerphone on? : " + am.isSpeakerphoneOn()); am.setSpeakerphoneOn(false); Log.d("SPEAKERPHONE", "Is speakerphone on? : " + am.isSpeakerphoneOn()); atrack.setPlaybackRate(11025); byte[] buffer = new byte[buffersize]; arec.startRecording(); atrack.play(); while(isRecording) { arec.read(buffer, 0, buffersize); atrack.write(buffer, 0, buffer.length); } arec.stop(); atrack.stop(); isRecording = false; } } } As you can see if the code I have tried using the AudioManager class and its methods including the deprecated setRouting method and nothing works, the setSpeatPoneOn method seems to have no effect at all, neither does the routing method. Has anyone got any ideas on how to get it to play via the earpiece instead of the spaker phone?

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• How to read an IIS 6 Website's Directory Structure using WMI?

  - by Steve Johnson

  I need to read a website's folders using WMI and C# in IIS 6.0. I am able to read the Virtual directories and applications using the "IISWebVirtualDirSetting" class. However the physical folders located inside a website cannot be read using this class. And for my case i need to read sub folders located within a website and later on set permission on them. For my requirement i dont need to work on Virtual Directories/Web Service Applications (which can be easily obtained using the code below..). I have tried to use IISWebDirectory class but it has been useful. Here is the code that reads IIS Virtual Directories... public static ArrayList RetrieveVirtualDirList(String ServerName, String WebsiteName) { ConnectionOptions options = SetUpAuthorization(); ManagementScope scope = new ManagementScope(string.Format(@"\\{0}\root\MicrosoftIISV2", ServerName), options); scope.Connect(); String SiteId = GetSiteIDFromSiteName(ServerName, WebsiteName); ObjectQuery OQuery = new ObjectQuery(@"SELECT * FROM IISWebVirtualDirSetting"); //ObjectQuery OQuery = new ObjectQuery(@"SELECT * FROM IIsSetting"); ManagementObjectSearcher WebSiteFinder = new ManagementObjectSearcher(scope, OQuery); ArrayList WebSiteListArray = new ArrayList(); ManagementObjectCollection WebSitesCollection = WebSiteFinder.Get(); String WebSiteName = String.Empty; foreach (ManagementObject WebSite in WebSitesCollection) { WebSiteName = WebSite.Properties["Name"].Value.ToString(); WebsiteName = WebSiteName.Replace("W3SVC/", ""); String extrctedSiteId = WebsiteName.Substring(0, WebsiteName.IndexOf('/')); String temp = WebsiteName.Substring(0, WebsiteName.IndexOf('/') + 1); String VirtualDirName = WebsiteName.Substring(temp.Length); WebsiteName = WebsiteName.Replace(SiteId, ""); if (extrctedSiteId.Equals(SiteId)) //if (true) { WebSiteListArray.Add(VirtualDirName ); //WebSiteListArray.Add(WebSiteName); //+ "|" + WebSite.Properties["Path"].Value.ToString() } } return WebSiteListArray; } P.S: I need to programmatically get the sub folders of an already deployed site(s) using WMI and C# in an ASP. Net Application. I need to find out the sub folders of existing websites in a local or remote IIS 6.0 Web Server. So i require a programmatic solution. Precisely if i am pointed at the right class (like IISWebVirtualDirSetting etc ) that i may use for retrieving the list of physical folders within a website then it will be quite helpful. I am not working in Powershell and i don't really need a solution that involves powershell or vbscripts. Any alternative programmatic way of doing the same in C#/ASP.Net will also be highly appreciated.

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• SerialPort ReadLine() after Thread.Sleep() goes crazy

  - by Mat

  Hi everybody, I've been fighting with this issue for a day and I can't find answer for it. I am trying to read data from GPS device trough COM port in Compact Framework C#. I am using SerialPort class (actually my own ComPort class boxing SerialPort, but it adds only two fields I need, nothing special). Anyway.. I am running while loop in a separate thread which reads line from the port, analyze NMEA data, print them, catch all exceptions and then I Sleep(200) the thread, cause I need CPU for other threads... Without Sleep it works fine, but uses 100% CPU.. When I dont use Sleep after few minutes the output from COM port looks like this: GPGSA,A,3,09,12,22,17,15,27,,,,,,,2.6,1.6,2.1*3F GSA,A,3,09,12,22,17,15,27,,,,,,,2.6,1.6,2.1*3F A,A,3,09,12,22,17,15,27,,,,,,,2.6,1.6,2.1*3F ,18,12,271,24,24,05,020,24,14,04,326,25,11,03,023,*76 A,3,09,12,22,17,15,27,,,,,,,2.6,1.6,2.1*3F 3,09,12,22,17,15,27,,,,,,,2.6,1.6,2.1*3F 09,12,22,17,15,27,,,,,,,2.6,1.6,2.1*3F ,12,22,17,15,27,,,,,,,2.6,1.6,2.1*3F as you can see the same message is read few times but cut. I wonder what I'm doing wrong... My port configuration: port.ReadBufferSize = 4096; port.BaudRate = 4800; port.DataBits = 8; port.Parity = Parity.None; port.StopBits = StopBits.One; port.NewLine = "\r\n"; port.ReadTimeout = 1000; port.ReceivedBytesThreshold = 100000; And my reading function: private void processGps(){ while (!closing) { //reconnect if needed try { string sentence = port.ReadLine(); //here print the sentence //analyze the sentence (this takes some time 50-100ms) } catch (TimeoutException) { Thread.Sleep(0); } catch (IOException ioex) { //handling IO exception (some info on the screen) } Thread.Sleep(200); } } There is some more stuff in this function like reconnection if the device is lost etc.. but it is not called when the GPS is connected properly.. I was trying port.DiscardInBuffer(); after some blocks of code (in TimeoutException, after read..) Did anyone had similar problem? I really dont know what I'm doing wrong.. The only way to get rig of it is removing the last Sleep... Thanks in advance! Best Regards, Mat

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• Using XMLDecoder to cast Encoded XML to List<>

  - by Ender

  I am writing an application that reads in a large number of basic user details in the following format; once read in it then allows the user to search for a user's details using their email: NAME ROLE EMAIL --------------------------------------------------- Joe Bloggs Manager [email protected] John Smith Consultant [email protected] Alan Wright Tester [email protected] ... The problem I am suffering is that I need to store a large number of details of all people that have worked at the company. The file containing these details will be written on a yearly basis simply for reporting purposes, but the program will need to be able to access these details quickly. The way I aim to access these files is to have a program that asks the user for the name of the unique email of the member of staff and for the program to then return the name and the role from that line of the file. I've played around with text files, but am struggling with how I would handle multiple columns of data when it comes to searching this large file. What is the best format to store such data in? A text file? XML? The size doesn't bother me, but I'd like to be able to search it as quickly as possible. The file will need to contain a lot of entries, probably over the 10K mark over time. EDIT: I've decided to go with the XML serialisation method. I've managed to get the code for Encoding working perfectly, but the Decoding code below does not work. XMLDecoder d = new XMLDecoder( new BufferedInputStream(new FileInputStream("data.xml"))); List<Employee> list = (List<Employee>) d.readObject(); d.close(); for(Employee x : list) { if(x.getEmail().equals(userInput)) { // do stuff } } When the program hits List<Employee> list = (List<Employee>) d.readObject(); an exception is thrown claiming that "Employee cannot be cast to java.util.List". I've added a bounty to this and anyone that can help me solve this problem once and for all will get lots of lovely points. EDIT 2: I've looked a bit more into the problem and have come across Serialization as a potential answer. If anyone can look into this for me as I've no experience with Serialization or Deserialization I'd be very grateful. It can provide an Object with no problems whatsoever, but I really need to return it in the same format as it went in (List). EDIT 3: Ugh, this problem is really starting to drive me crazy and to be honest I'm starting to think that it's an unsolvable problem. If possible, could someone take a look at the code and help provide a solution for me?

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• Reproduce PIPE functionality in IronPython

  - by Muppet Geoff

  Hi, I am hoping some genious out there can help me out with this... I am using sox to merge and resample a group of WAV files, and pipe the output directly to the input of NeroAACEnc for encoding to AAC format. I originally ran the process in a script, which included: sox.exe d:\audio\1.wav d:\audio\2.wav d:\audio\3.wav -c 1 -r 22050 -t wav - | neroAacEnc.exe -q 0.5 -if - -of test.m4a This worked as expected. The '-' in the comand line translates as 'Pipe/redirect input/output (stdin/stdout)' - So Sox pipes to stdout, and NeroAACEnc reads from stdin, the | joins them together. I then migrated the whole solution to Python, and the equivalent command became: from subprocess import call, Popen, PIPE runwav = Popen(['sox.exe', 'd:\audio\1.wav', 'd:\audio\2.wav', 'd:\audio\3.wav', '-c', '1', '-r', '22050', '-t', 'wav', '-'], shell=False, stdout=PIPE) runm4b = call(['neroAacEnc.exe', '-q', '0.5', '-if', '-', '-of', 'test.m4a'], shell=False, stdin=runwav.stdout) This also worked like a charm, exactly as expected. Slightly more convoluted, but hey :) Well now I have to move it to IronPython, and the Subprocess module isn't available (the partial implementation that is, doesn't have Popen/PIPE support - plus it seems silly to add a custom library when there is probably a native alternative). I should mention here, that I opted for IronPython over C#, because I am comfortable with Python now - however, there is a chance of moving it again later to C# native, and I am using IronPython to ease myself into it :) I have no C# or .net experience. So far I have the following equivalent, that sets up the 2 processes: from System.Diagnostics import Process wav = Process() wav.StartInfo.UseShellExecute = False wav.StartInfo.RedirectStandardOutput = True wav.StartInfo.FileName = 'sox.exe' wav.StartInfo.Arguments = 'd:\audio\1.wav d:\audio\2.wav d:\audio\3.wav -c 1 -r 22050 -t wav -' wav.Start() m4b = Process() m4b.StartInfo.UseShellExecute = False m4b.StartInfo.RedirectStandardInput = True m4b.StartInfo.FileName = 'neroAacEnc.exe' m4b.StartInfo.Arguments = '-q 0.5 -if - -of test.m4a' m4b.Start() I know that these 2 processes start (I can see Nero and Sox in the task manager) but what I can't figure out (for the life of me) is how to string the two output/input streams together, as with the previous two solutions. I have searched and searched, so I thought I'd ask! If anyone knows either: How to join the two streams with the same net result as the Python and Commandline versions; or A better way to acheive what I am trying to do. I would be extremely grateful! Many thanks in advance, Geoff P.S. A code sample based off the above would be awesome :) or a specific code example of a similar process that I can easily translate... this has broked my brayne.

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• DevExpress Reporting Session Issue

  - by LeeHull

  This is pretty complicated so I will explain what is going on. I have created an ASP.NET website for displaying images, the way we use our images is, we have a database table that contains the URL where the images are located, however we recently started moving them from the filesystem, and storing them directly into the database as binary, but since we don't want to break older applications, we currently store them both places till they are all updated. Alright, the website I'm working on, is just a reporting website to display images by a date range, I have created an HTTPHandler to display the image, depending if they exist in the database as binary, if the row is DBNull, I just grab the URL from the other table instead, I just read the image, convert it into a byte[] and write it to the response, so it is interpreted as an image. I have created a page to display the report using DevExpress Reporting, I just query the report, save the dataset into a session, and the report reads the session to bind the report, i also have a picturebox in the report bound to "Handler.ashx?id=ImageID", this is because I am not binding a URL to the image, since it is a byte[] Also since there could be a report with 10000+ images, I am reading the dataset from the session inside the handler and just pulling out the image from the passed in ImageID, I am doing this to prevent connecting to the database each and every row. Now the strange thing is, Report loads fine.. data is loading, I have paging on the devexpress report viewer, it is loading the images fine, however here is the issue. When I print or export, I am not getting any images, I am debugged and found out the Session.Count is 0 when it tries to print or export, which is strange since there is more than just the dataset in the session. I have also added IRequiresSessionState to allow sessions in the handler, but the session count is still 0, I have changing the Handler to an aspx page, same issue. Any ideas or suggestions on logic changes, I'm all ears.. this is a very difficult situation since I have to display the images from database as a string AND byte[] since one can be URL and other be the image bytes, but I also can't slam the database on connection calls each row either. I have also reported the issue to DevExpress and they are clueless as well, since they don't dispose the session in the exporting process.

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• NHibernate, transactions and TransactionScope

  - by Erik

  I'm trying to find the best solution to handle transaction in a web application that uses NHibernate. We use a IHttpModule and at HttpApplication.BeginRequest we open a new session and we bind it to the HttpContext with ManagedWebSessionContext.Bind(context, session); We close and unbind the session on HttpApplication.EndRequest. In our Repository base class, we always wrapped a transaction around our SaveOrUpdate, Delete, Get methods like, according to best practice: public virtual void Save(T entity) { var session = DependencyManager.Resolve<ISession>(); using (var transaction = session.BeginTransaction()) { session.SaveOrUpdate(entity); transaction.Commit(); } } But then this doesn't work, if you need to put a transaction somewhere in e.g. a Application service to include several repository calls to Save, Delete, etc.. So what we tried is to use TransactionScope (I didn't want to write my own transactionmanager). To test that this worked, I use an outer TransactionScope that doesn't call .Complete() to force a rollback: Repository Save(): public virtual void Save(T entity) { using (TransactionScope scope = new TransactionScope()) { var session = Depe.ndencyManager.Resolve<ISession>(); session.SaveOrUpdate(entity); scope.Complete(); } } The block that uses the repository: TestEntity testEntity = new TestEntity { Text = "Test1" }; ITestRepository testRepository = DependencyManager.Resolve<ITestRepository>(); testRepository.Save(testEntity); using (var scope = new TransactionScope()) { TestEntity entityToChange = testRepository.GetById(testEntity.Id); entityToChange.Text = "TestChanged"; testRepository.Save(entityToChange); } TestEntity entityChanged = testRepository.GetById(testEntity.Id); Assert.That(entityChanged.Text, Is.EqualTo("Test1")); This doesn't work. But to me if NHibernate supports TransactionScope it would! What happens is that there is no ROLLBACK at all in the database but when the testRepository.GetById(testEntity.Id); statement is executed a UPDATE with SET Text = "TestCahgned" is fired instead (It should have been fired between BEGIN TRAN and ROLLBACK TRAN). NHibernate reads the value from the level1 cache and fires a UPDATE to the database. Not expected behaviour!? From what I understand whenever a rollback is done in the scope of NHibernate you also need to close and unbind the current session. My question is: Does anyone know of a good way to do this using TransactionScope and ManagedWebSessionContext?

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• NoHostAvailableException With Cassandra & DataStax Java Driver If Large ResultSet

  - by hughj

  The setup: 2-node Cassandra 1.2.6 cluster replicas=2 very large CQL3 table with no secondary index Rowkey is a UUID.randomUUID().toString() read consistency set to ONE Using DataStax java driver 1.0 The request: Attempting to do a table scan by "SELECT some-col from schema.table LIMIT nnn;" The fail: Once I go beyond a certain nnn LIMIT, I start to get NoHostAvailableExceptions from the driver. It reads like this: com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s) tried for query failed (tried: /10.181.13.239 ([/10.181.13.239] Unexpected exception triggered)) at com.datastax.driver.core.exceptions.NoHostAvailableException.copy(NoHostAvailableException.java:64) at com.datastax.driver.core.ResultSetFuture.extractCauseFromExecutionException(ResultSetFuture.java:214) at com.datastax.driver.core.ResultSetFuture.getUninterruptibly(ResultSetFuture.java:169) at com.jpmc.es.rtm.storage.impl.EventExtract.main(EventExtract.java:36) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:601) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120) Caused by: com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s) tried for query failed (tried: /10.181.13.239 ([/10.181.13.239] Unexpected exception triggered)) at com.datastax.driver.core.RequestHandler.sendRequest(RequestHandler.java:98) at com.datastax.driver.core.RequestHandler$1.run(RequestHandler.java:165) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) Given: This is probably not the most enlightened thing to do to a large table with millions of rows, but this is how I learn what not to do, so I would really appreciate someone who could volunteer how this kind of error can be debugged. For example, when this happens, there are no indications that the nodes in the cluster ever had an issue with the request (there is nothing in the logs on either node that indicate any timeout or failure). Also, I enabled the trace on the driver, which gives you some nice autotrace (ala Oracle) info as long as the query succeeds. But in this case, the driver blows a NoHostAvailableException and no ExecutionInfo is available, so tracing has not provided any benefit in this case. I also find it interesting that this does not seem to be recorded as a timeout (my JMX consoles tell me no timeouts have occurred). So, I am left not understanding WHERE the failure is actually occurring. I am left with the idea that it is the driver that is having a problem, but I don't know how to debug it (and I would really like to). I have read several posts from folks that state that query'g for resultSets 10000 rows is probably not a good idea, and I am willing to accept this, but I would like to understand what is causing the exception and where the exception is happening. FWIW, I also tried bumping the timeout properties in the cassandra.yaml, but this made no difference whatsoever. I welcome any suggestions, anecdotes, insults, or monetary contributions for my registration in the house of moron-developers. Regards!!

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