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• Customers Discuss: Real-World Operational Reporting with Oracle GoldenGate

  - by Irem Radzik

  Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;} As businesses leverage business intelligence and analytics for day-to-day decision making, operational reporting solutions become more and more common. While some companies can use their production OLTP system for running operational reports, for many it is too much overhead and performance impact for transaction processing systems.  Oracle GoldenGate’s real-time data integration capabilities enable companies to create a real-time replica of their OLTP systems, dedicated for operational reporting. This instance can be optimized for the reports needed as well such as containing only the tables needed from the source. Oracle GoldenGate has certified solutions for many Oracle applications such as EBusiness Suite, Peoplesoft, JD Edwards, to offload operational reporting to another reporting server that has real-time data feeding from the production system. At Oracle OpenWorld we will be hearing from a panel of Oracle GoldenGate customers how they deployed GoldenGate for operational reporting. Comcast, Turk Telekom, and Raymond James will be sharing their experiences and the benefits achieved when implementing GoldenGate’s solution. If you have performance degradation in your production systems due to reporting or ad-hoc queries, and you will be at OpenWorld, don’t miss this informative session: Real-World Operational Reporting with Oracle GoldenGate: Customer Panel-- Tuesday Oct 2nd 11:45am Mascone West 3005. For other data integration sessions at OpenWorld, please check our Focus-On document.  Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;} If you cannot attend OpenWorld, please check out related white paper “Using Oracle GoldenGate to Achieve Operational Reporting for Oracle Applications” to learn more.

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• Efficiently separating Read/Compute/Write steps for concurrent processing of entities in Entity/Component systems

  - by TravisG

  Setup I have an entity-component architecture where Entities can have a set of attributes (which are pure data with no behavior) and there exist systems that run the entity logic which act on that data. Essentially, in somewhat pseudo-code: Entity { id; map<id_type, Attribute> attributes; } System { update(); vector<Entity> entities; } A system that just moves along all entities at a constant rate might be MovementSystem extends System { update() { for each entity in entities position = entity.attributes["position"]; position += vec3(1,1,1); } } Essentially, I'm trying to parallelise update() as efficiently as possible. This can be done by running entire systems in parallel, or by giving each update() of one system a couple of components so different threads can execute the update of the same system, but for a different subset of entities registered with that system. Problem In reality, these systems sometimes require that entities interact(/read/write data from/to) each other, sometimes within the same system (e.g. an AI system that reads state from other entities surrounding the current processed entity), but sometimes between different systems that depend on each other (i.e. a movement system that requires data from a system that processes user input). Now, when trying to parallelize the update phases of entity/component systems, the phases in which data (components/attributes) from Entities are read and used to compute something, and the phase where the modified data is written back to entities need to be separated in order to avoid data races. Otherwise the only way (not taking into account just "critical section"ing everything) to avoid them is to serialize parts of the update process that depend on other parts. This seems ugly. To me it would seem more elegant to be able to (ideally) have all processing running in parallel, where a system may read data from all entities as it wishes, but doesn't write modifications to that data back until some later point. The fact that this is even possible is based on the assumption that modification write-backs are usually very small in complexity, and don't require much performance, whereas computations are very expensive (relatively). So the overhead added by a delayed-write phase might be evened out by more efficient updating of entities (by having threads work more % of the time instead of waiting). A concrete example of this might be a system that updates physics. The system needs to both read and write a lot of data to and from entities. Optimally, there would be a system in place where all available threads update a subset of all entities registered with the physics system. In the case of the physics system this isn't trivially possible because of race conditions. So without a workaround, we would have to find other systems to run in parallel (which don't modify the same data as the physics system), other wise the remaining threads are waiting and wasting time. However, that has disadvantages Practically, the L3 cache is pretty much always better utilized when updating a large system with multiple threads, as opposed to multiple systems at once, which all act on different sets of data. Finding and assembling other systems to run in parallel can be extremely time consuming to design well enough to optimize performance. Sometimes, it might even not be possible at all because a system just depends on data that is touched by all other systems. Solution? In my thinking, a possible solution would be a system where reading/updating and writing of data is separated, so that in one expensive phase, systems only read data and compute what they need to compute, and then in a separate, performance-wise cheap, write phase, attributes of entities that needed to be modified are finally written back to the entities. The Question How might such a system be implemented to achieve optimal performance, as well as making programmer life easier? What are the implementation details of such a system and what might have to be changed in the existing EC-architecture to accommodate this solution?

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• Learn Many Languages

  - by Jeff Foster

  My previous blog, Deliberate Practice, discussed the need for developers to “sharpen their pencil” continually, by setting aside time to learn how to tackle problems in different ways. However, the Sapir-Whorf hypothesis, a contested and somewhat-controversial concept from language theory, seems to hold reasonably true when applied to programming languages. It states that: “The structure of a language affects the ways in which its speakers conceptualize their world.” If you’re constrained by a single programming language, the one that dominates your day job, then you only have the tools of that language at your disposal to think about and solve a problem. For example, if you’ve only ever worked with Java, you would never think of passing a function to a method. A good developer needs to learn many languages. You may never deploy them in production, you may never ship code with them, but by learning a new language, you’ll have new ideas that will transfer to your current “day-job” language. With the abundant choices in programming languages, how does one choose which to learn? Alan Perlis sums it up best. “A language that doesn‘t affect the way you think about programming is not worth knowing“ With that in mind, here’s a selection of languages that I think are worth learning and that have certainly changed the way I think about tackling programming problems. Clojure Clojure is a Lisp-based language running on the Java Virtual Machine. The unique property of Lisp is homoiconicity, which means that a Lisp program is a Lisp data structure, and vice-versa. Since we can treat Lisp programs as Lisp data structures, we can write our code generation in the same style as our code. This gives Lisp a uniquely powerful macro system, and makes it ideal for implementing domain specific languages. Clojure also makes software transactional memory a first-class citizen, giving us a new approach to concurrency and dealing with the problems of shared state. Haskell Haskell is a strongly typed, functional programming language. Haskell’s type system is far richer than C# or Java, and allows us to push more of our application logic to compile-time safety. If it compiles, it usually works! Haskell is also a lazy language – we can work with infinite data structures. For example, in a board game we can generate the complete game tree, even if there are billions of possibilities, because the values are computed only as they are needed. Erlang Erlang is a functional language with a strong emphasis on reliability. Erlang’s approach to concurrency uses message passing instead of shared variables, with strong support from both the language itself and the virtual machine. Processes are extremely lightweight, and garbage collection doesn’t require all processes to be paused at the same time, making it feasible for a single program to use millions of processes at once, all without the mental overhead of managing shared state. The Benefits of Multilingualism By studying new languages, even if you won’t ever get the chance to use them in production, you will find yourself open to new ideas and ways of coding in your main language. For example, studying Haskell has taught me that you can do so much more with types and has changed my programming style in C#. A type represents some state a program should have, and a type should not be able to represent an invalid state. I often find myself refactoring methods like this… void SomeMethod(bool doThis, bool doThat) { if (!(doThis ^ doThat)) throw new ArgumentException(“At least one arg should be true”); if (doThis) DoThis(); if (doThat) DoThat(); } …into a type-based solution, like this: enum Action { DoThis, DoThat, Both }; void SomeMethod(Action action) { if (action == Action.DoThis || action == Action.Both) DoThis(); if (action == Action.DoThat || action == Action.Both) DoThat(); } At this point, I’ve removed the runtime exception in favor of a compile-time check. This is a trivial example, but is just one of many ideas that I’ve taken from one language and implemented in another.

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• Profiling Startup Of VS2012 &ndash; dotTrace Profiler

  - by Alois Kraus

  Jetbrains which is famous for the Resharper tool has also a profiler in its portfolio. I downloaded dotTrace 5.2 Professional (569€+VAT) to check how far I can profile the startup of VS2012. The most interesting startup option is “.NET Process”. With that you can profile the next started .NET process which is very useful if you want to profile an application which is not started by you.     I did select Tracing as and Wall time to get similar options across all profilers. For some reason the attach option did not work with .NET 4.5 on my home machine. But I am sure that it did work with .NET 4.0 some time ago. Since we are profiling devenv.exe we can also select “Standalone Application” and start it from the profiler. The startup time of VS does increase about a factor 3 but that is ok. You get mainly three windows to work with. The first one shows the threads where you can drill down thread wise where most time is spent. I The next window is the call tree which does merge all threads together in a similar view. The last and most useful view in my opinion is the Plain List window which is nearly the same as the Method Grid in Ants Profiler. But this time we do get when I enable the Show system functions checkbox not a 150 but 19407 methods to choose from! I really tried with Ants Profiler to find something about out how VS does work but look how much we were missing! When I double click on a method I do get in the lower pane the called methods and their respective timings. This is something really useful and I can nicely drill down to the most important stuff. The measured time seems to be Wall Clock time which is a good thing to see where my time is really spent. You can also use Sampling as profiling method but this does give you much less information. Except for getting a first idea where to look first this profiling mode is not very useful to understand how you system does interact.   The options have a good list of presets to hide by default many method and gray them out to concentrate on your code. It does not filter anything out if you enable Show system functions. By default methods from these assemblies are hidden or if the checkbox is checked grayed out. All in all JetBrains has made a nice profiler which does show great detail and it has nice drill down capabilities. The only thing is that I do not trust its measured timings. I did fall several times into the trap with this one to optimize at places which were already fast but the profiler did show high times in these methods. After measuring with Tracing I was certain that the measured times were greatly exaggerated. Especially when IO is involved it seems to have a hard time to subtract its own overhead. What I did miss most was the possibility to profile not only the next started process but to be able to select a process by name and perhaps a count to profile the next n processes of this name. Next: YourKit

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• Editing files without race conditions?

  - by user2569445

  I have a CSV file that needs to be edited by multiple processes at the same time. My question is, how can I do this without introducing race conditions? It's easy to write to the end of the file without race conditions by open(2)ing it in "a" (O_APPEND) mode and simply write to it. Things get more difficult when removing lines from the file. The easiest solution is to read the file into memory, make changes to it, and overwrite it back to the file. If another process writes to it after it is in memory, however, that new data will be lost upon overwriting. To further complicate matters, my platform does not support POSIX record locks, checking for file existence is a race condition waiting to happen, rename(2) replaces the destination file if it exists instead of failing, and editing files in-place leaves empty bytes in it unless the remaining bytes are shifted towards the beginning of the file. My idea for removing a line is this (in pseudocode): filename = "/home/user/somefile"; file = open(filename, "r"); tmp = open(filename+".tmp", "ax") || die("could not create tmp file"); //"a" is O_APPEND, "x" is O_EXCL|O_CREAT while(write(tmp, read(file)); //copy the $file to $file+".new" close(file); //edit tmp file unlink(filename) || die("could not unlink file"); file = open(filename, "wx") || die("another process must have written to the file after we copied it."); //"w" is overwrite, "x" is force file creation while(write(file, read(tmp))); //copy ".tmp" back to the original file unlink(filename+".tmp") || die("could not unlink tmp file"); Or would I be better off with a simple lock file? Appender process: lock = open(filename+".lock", "wx") || die("could not lock file"); file = open(filename, "a"); write(file, "stuff"); close(file); close(lock); unlink(filename+".lock"); Editor process: lock = open(filename+".lock", "wx") || die("could not lock file"); file = open(filename, "rw"); while(contents += read(file)); //edit "contents" write(file, contents); close(file); close(lock); unlink(filename+".lock"); Both of these rely on an additional file that will be left over if a process terminates before unlinking it, causing other processes to refuse to write to the original file. In my opinion, these problems are brought on by the fact that the OS allows multiple writable file descriptors to be opened on the same file at the same time, instead of failing if a writable file descriptor is already open. It seems that O_CREAT|O_EXCL is the closest thing to a real solution for preventing filesystem race conditions, aside from POSIX record locks. Another possible solution is to separate the file into multiple files and directories, so that more granular control can be gained over components (lines, fields) of the file using O_CREAT|O_EXCL. For example, "file/$id/$field" would contain the value of column $field of the line $id. It wouldn't be a CSV file anymore, but it might just work. Yes, I know I should be using a database for this as databases are built to handle these types of problems, but the program is relatively simple and I was hoping to avoid the overhead. So, would any of these patterns work? Is there a better way? Any insight into these kinds of problems would be appreciated.

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• Using WKA in Large Coherence Clusters (Disabling Multicast)

  - by jpurdy

  Disabling hardware multicast (by configuring well-known addresses aka WKA) will place significant stress on the network. For messages that must be sent to multiple servers, rather than having a server send a single packet to the switch and having the switch broadcast that packet to the rest of the cluster, the server must send a packet to each of the other servers. While hardware varies significantly, consider that a server with a single gigabit connection can send at most ~70,000 packets per second. To continue with some concrete numbers, in a cluster with 500 members, that means that each server can send at most 140 cluster-wide messages per second. And if there are 10 cluster members on each physical machine, that number shrinks to 14 cluster-wide messages per second (or with only mild hyperbole, roughly zero). It is also important to keep in mind that network I/O is not only expensive in terms of the network itself, but also the consumption of CPU required to send (or receive) a message (due to things like copying the packet bytes, processing a interrupt, etc). Fortunately, Coherence is designed to rely primarily on point-to-point messages, but there are some features that are inherently one-to-many: Announcing the arrival or departure of a member Updating partition assignment maps across the cluster Creating or destroying a NamedCache Invalidating a cache entry from a large number of client-side near caches Distributing a filter-based request across the full set of cache servers (e.g. queries, aggregators and entry processors) Invoking clear() on a NamedCache The first few of these are operations that are primarily routed through a single senior member, and also occur infrequently, so they usually are not a primary consideration. There are cases, however, where the load from introducing new members can be substantial (to the point of destabilizing the cluster). Consider the case where cluster in the first paragraph grows from 500 members to 1000 members (holding the number of physical machines constant). During this period, there will be 500 new member introductions, each of which may consist of several cluster-wide operations (for the cluster membership itself as well as the partitioned cache services, replicated cache services, invocation services, management services, etc). Note that all of these introductions will route through that one senior member, which is sharing its network bandwidth with several other members (which will be communicating to a lesser degree with other members throughout this process). While each service may have a distinct senior member, there's a good chance during initial startup that a single member will be the senior for all services (if those services start on the senior before the second member joins the cluster). It's obvious that this could cause CPU and/or network starvation. In the current release of Coherence (3.7.1.3 as of this writing), the pure unicast code path also has less sophisticated flow-control for cluster-wide messages (compared to the multicast-enabled code path), which may also result in significant heap consumption on the senior member's JVM (from the message backlog). This is almost never a problem in practice, but with sufficient CPU or network starvation, it could become critical. For the non-operational concerns (near caches, queries, etc), the application itself will determine how much load is placed on the cluster. Applications intended for deployment in a pure unicast environment should be careful to avoid excessive dependence on these features. Even in an environment with multicast support, these operations may scale poorly since even with a constant request rate, the underlying workload will increase at roughly the same rate as the underlying resources are added. Unless there is an infrastructural requirement to the contrary, multicast should be enabled. If it can't be enabled, care should be taken to ensure the added overhead doesn't lead to performance or stability issues. This is particularly crucial in large clusters.

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• Don’t string together XML

  - by KyleBurns

  XML has been a pervasive tool in software development for over a decade.  It provides a way to communicate data in a manner that is simple to understand and free of platform dependencies.  Also pervasive in software development is what I consider to be the anti-pattern of using string manipulation to create XML.  This usually starts with a “quick and dirty” approach because you need an XML document and looks like (for all of the examples here, we’ll assume we’re writing the body of a method intended to take a Contact object and return an XML string): return string.Format("<Contact><BusinessName>{0}</BusinessName></Contact>", contact.BusinessName);   In the code example, I created (or at least believe I created) an XML document representing a simple contact object in one line of code with very little overhead.  Work’s done, right?  No it’s not.  You see, what I didn’t realize was that this code would be used in the real world instead of my fantasy world where I own all the data and can prevent any of it containing problematic values.  If I use this code to create a contact record for the business “Sanford & Son”, any XML parser will be incapable of processing the data because the ampersand is special in XML and should have been encoded as &amp;. Following the pattern that I have seen many times over, my next step as a developer is going to be to do what any developer in his right mind would do – instruct the user that ampersands are “bad” and they cannot be used without breaking computers.  This may work in many cases and is often accompanied by logic at the UI layer of applications to block these “bad” characters, but sooner or later someone is going to figure out that other applications allow for them and will want the same.  This often leads to the creation of “cleaner” functions that perform a replace on the strings for every special character that the person writing the function can think of.  The cleaner function will usually grow over time as support requests reveal characters that were missed in the initial cut.  Sooner or later you end up writing your own somewhat functional XML engine. I have never been told by anyone paying me to write code that they would like to buy a somewhat functional XML engine.  My employer/customer’s needs have always been for something that may use XML, but ultimately is functionality that drives business value. I’m not going to build an XML engine. So how can I generate XML that is always well-formed without writing my own engine?  Easy – use one of the ones provided to you for free!  If you’re in a shop that still supports VB6 applications, you can use the DomDocument or MXXMLWriter object (of the two I prefer MXXMLWriter, but I’m not going to fully describe either here).  For .Net Framework applications prior to the 3.5 framework, the code is a little more verbose than I would like, but easy once you understand what pieces are required:             using (StringWriter sw = new StringWriter())             {                 using (XmlTextWriter writer = new XmlTextWriter(sw))                 {                     writer.WriteStartDocument();                     writer.WriteStartElement("Contact");                     writer.WriteElementString("BusinessName", contact.BusinessName);                     writer.WriteEndElement(); // end Contact element                     writer.WriteEndDocument();                     writer.Flush();                     return sw.ToString();                 }             }   Looking at that code, it’s easy to understand why people are drawn to the initial one-liner.  Lucky for us, the 3.5 .Net Framework added the System.Xml.Linq.XElement object.  This object takes away a lot of the complexity present in the XmlTextWriter approach and allows us to generate the document as follows: return new XElement("Contact", new XElement("BusinessName", contact.BusinessName)).ToString();   While it is very common for people to use string manipulation to create XML, I’ve discussed here reasons not to use this method and introduced powerful APIs that are built into the .Net Framework as an alternative.  I’ve given a very simplistic example here to highlight the most basic XML generation task.  For more information on the XmlTextWriter and XElement APIs, check out the MSDN library.

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• High Resolution Timeouts

  - by user12607257

  The default resolution of application timers and timeouts is now 1 msec in Solaris 11.1, down from 10 msec in previous releases. This improves out-of-the-box performance of polling and event based applications, such as ticker applications, and even the Oracle rdbms log writer. More on that in a moment. As a simple example, the poll() system call takes a timeout argument in units of msec: System Calls poll(2) NAME poll - input/output multiplexing SYNOPSIS int poll(struct pollfd fds[], nfds_t nfds, int timeout); In Solaris 11, a call to poll(NULL,0,1) returns in 10 msec, because even though a 1 msec interval is requested, the implementation rounds to the system clock resolution of 10 msec. In Solaris 11.1, this call returns in 1 msec. In specification lawyer terms, the resolution of CLOCK_REALTIME, introduced by POSIX.1b real time extensions, is now 1 msec. The function clock_getres(CLOCK_REALTIME,&res) returns 1 msec, and any library calls whose man page explicitly mention CLOCK_REALTIME, such as nanosleep(), are subject to the new resolution. Additionally, many legacy functions that pre-date POSIX.1b and do not explicitly mention a clock domain, such as poll(), are subject to the new resolution. Here is a fairly comprehensive list: nanosleep pthread_mutex_timedlock pthread_mutex_reltimedlock_np pthread_rwlock_timedrdlock pthread_rwlock_reltimedrdlock_np pthread_rwlock_timedwrlock pthread_rwlock_reltimedwrlock_np mq_timedreceive mq_reltimedreceive_np mq_timedsend mq_reltimedsend_np sem_timedwait sem_reltimedwait_np poll select pselect _lwp_cond_timedwait _lwp_cond_reltimedwait semtimedop sigtimedwait aiowait aio_waitn aio_suspend port_get port_getn cond_timedwait cond_reltimedwait setitimer (ITIMER_REAL) misc rpc calls, misc ldap calls This change in resolution was made feasible because we made the implementation of timeouts more efficient a few years back when we re-architected the callout subsystem of Solaris. Previously, timeouts were tested and expired by the kernel's clock thread which ran 100 times per second, yielding a resolution of 10 msec. This did not scale, as timeouts could be posted by every CPU, but were expired by only a single thread. The resolution could be changed by setting hires_tick=1 in /etc/system, but this caused the clock thread to run at 1000 Hz, which made the potential scalability problem worse. Given enough CPUs posting enough timeouts, the clock thread could be a performance bottleneck. We fixed that by re-implementing the timeout as a per-CPU timer interrupt (using the cyclic subsystem, for those familiar with Solaris internals). This decoupled the clock thread frequency from timeout resolution, and allowed us to improve default timeout resolution without adding CPU overhead in the clock thread. Here are some exceptions for which the default resolution is still 10 msec. The thread scheduler's time quantum is 10 msec by default, because preemption is driven by the clock thread (plus helper threads for scalability). See for example dispadmin, priocntl, fx_dptbl, rt_dptbl, and ts_dptbl. This may be changed using hires_tick. The resolution of the clock_t data type, primarily used in DDI functions, is 10 msec. It may be changed using hires_tick. These functions are only used by developers writing kernel modules. A few functions that pre-date POSIX CLOCK_REALTIME mention _SC_CLK_TCK, CLK_TCK, "system clock", or no clock domain. These functions are still driven by the clock thread, and their resolution is 10 msec. They include alarm, pcsample, times, clock, and setitimer for ITIMER_VIRTUAL and ITIMER_PROF. Their resolution may be changed using hires_tick. Now back to the database. How does this help the Oracle log writer? Foreground processes post a redo record to the log writer, which releases them after the redo has committed. When a large number of foregrounds are waiting, the release step can slow down the log writer, so under heavy load, the foregrounds switch to a mode where they poll for completion. This scales better because every foreground can poll independently, but at the cost of waiting the minimum polling interval. That was 10 msec, but is now 1 msec in Solaris 11.1, so the foregrounds process transactions faster under load. Pretty cool.

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• Border image on UIView

  - by drunknbass

  I want to have a UIView subclass that has a border image, but i dont want or care about this 'new' frame/bounds around the border image itself. What i wanted to do was just use drawRect and draw outside of the rect but all drawing is clipped and i dont see a way to not clip drawing outside of this context rect. So now i have added a sublayer to the views layer, set [self clipsToBounds] on the view and override setFrame to control my sublayers frame and always keep it at the proper size (spilling over the views frame by 40px) the problem with this is that setFrame on a uiview by default has no animation but seTFrame on a calayer does. i cant just disable the animations on the calayers setFrame because if i were to call setFrame on the uiview inside a uiview animation block the calayer would still have its animation disabled. the obvious solution is to look up the current animationDuration on the uiview animation and set a matching animation on the sublayer, but i dont know if this value is available. And even if it is, im afraid that calling an animation from within another animation is wrong. Unfortunately the best solution is to not use a calayer at all and just add a uiview as a subview and draw into that just like i am drawing into my layer, and hope that with autoresizingMask set to height and width that everything will 'just work'. Just seems like unnecessary overhead for such a simple task.

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• Cocoa equivalent of the Carbon method getPtrSize

  - by Michael Minerva

  I need to translate the a carbon method into cocoa into and I am having trouble finding any documentation about what the carbon method getPtrSize really does. From the code I am translating it seems that it returns the byte representation of an image but that doesn't really match up with the name. Could someone give me a good explanation of this method or link me to some documentation that describes it. The code I am translating is in a common lisp implementation called MCL that has a bridge to carbon (I am translating into CCL which is a common lisp implementation with a Cocoa bridge). Here is the MCL code (#_before a method call means that it is a carbon method): (defmethod COPY-CONTENT-INTO ((Source inflatable-icon) (Destination inflatable-icon)) ;; check for size compatibility to avoid disaster (unless (and (= (rows Source) (rows Destination)) (= (columns Source) (columns Destination)) (= (#_getPtrSize (image Source)) (#_getPtrSize (image Destination)))) (error "cannot copy content of source into destination inflatable icon: incompatible sizes")) ;; given that they are the same size only copy content (setf (is-upright Destination) (is-upright Source)) (setf (height Destination) (height Source)) (setf (dz Destination) (dz Source)) (setf (surfaces Destination) (surfaces Source)) (setf (distance Destination) (distance Source)) ;; arrays (noise-map Source) ;; accessor makes array if needed (noise-map Destination) ;; ;; accessor makes array if needed (dotimes (Row (rows Source)) (dotimes (Column (columns Source)) (setf (aref (noise-map Destination) Row Column) (aref (noise-map Source) Row Column)) (setf (aref (altitudes Destination) Row Column) (aref (altitudes Source) Row Column)))) (setf (connectors Destination) (mapcar #'copy-instance (connectors Source))) (setf (visible-alpha-threshold Destination) (visible-alpha-threshold Source)) ;; copy Image: slow byte copy (dotimes (I (#_getPtrSize (image Source))) (%put-byte (image Destination) (%get-byte (image Source) i) i)) ;; flat texture optimization: do not copy texture-id -> destination should get its own texture id from OpenGL (setf (is-flat Destination) (is-flat Source)) ;; do not compile flat textures: the display list overhead slows things down by about 2x (setf (auto-compile Destination) (not (is-flat Source))) ;; to make change visible we have to reset the compiled flag (setf (is-compiled Destination) nil))

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• How to populate a generic list of objects in C# from SQL database

  - by developr

  I am just learning ASP.NET c# and trying to incorporate best practices into my applications. Everything that I read says to layer my applications into DAL, BLL, UI, etc based on separation of concerns. Instead of passing datatables around, I am thinking about using custom objects so that I am loosely coupled to my data layer and can take advantage of intellisense in VS. I assume these objects would be considered DTOs? First, where do these objects reside in my layers? BLL, DAL, other? Second, when populating from SQL, should I loop through a data reader to populate the list or first fill a data table, then loop through the table to populate the list? I know you should close the database connection as soon as possible, but it seems like even more overhead to populate the data table and then loop through that for the list. Third, everything I see these days says use Linq2SQL. I am planning to learn Linq2SQL, but at this time I am working with a legacy database that doesn't have foreign keys setup and I do not have the ability to fix it atm. Also, I want to learn more about c# before I start getting into ORM solutions like nHibernate. At the same time I don't want to type out all the connection and SQL plumbing for every query. Is it ok to use the Enterprise DAAB for now?

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• Home automation using Arduino / XMPP client for Arduino

  - by Ashish

  I am trying to setup a system for automating certain tasks in my home. I am thinking of a solution wherein a server side application would be able to send/receive commands/data to Arduino (attached with Arduino Ethernet Shield) via the web. Here the Arduino may both act as a sensor interface to the server application or command executor interface for the server app. E.g. (user story): The overhead water tank in my house has a water level sensor attached with Arduino (attached with Arduino Ethernet Shield). Another Arduino (attached with Arduino Ethernet Shield) is attached with a relay/latch. This relay/latch is then connected to a water pump. Now the server side application on the web is able to get/receive water level information from the Arduino on the water tank. Depending on the water level information received, the web application should send suitable signals/commands to Arduino on water pump to switch 'ON' or switch 'OFF' the water pump. Now for such a system to work across the web, I am thinking of using one of the type of solutions in order of my priority: Using XMPP for communication between server application and Arduino. Using HTTP polling. Using HTTP hanging GET. For solution number 1, I need to implement a XMPP client that would reside on Arduino. Is it possible to write a XMPP client small enough to reside on an Arduino? If yes what are the minimum possible XMPP client functionality that I need to write for Arduino, so that it would be able to contact XMPP servers solutions like GTalk, etc.? For solution number 2 and 3 I need guidance in implementation. Also which solution would be cost effective and easily extendable?

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• Interpolation and Morphing of an image in labview and/or openCV

  - by Marc

  I am working on an image manipulation problem. I have an overhead projector that projects onto a screen, and I have a camera that takes pictures of that. I can establish a 1:1 correspondence between a subset of projector coordinates and a subset of camera pixels by projecting dots on the screen and finding the centers of mass of the resulting regions on the camera. I thus have a map proj_x, proj_y <-- cam_x, cam_y for scattered point pairs My original plan was to regularize this map using the Mathscript function griddata. This would work fine in MATLAB, as follows [pgridx, pgridy] = meshgrid(allprojxpts, allprojypts) fitcx = griddata (proj_x, proj_y, cam_x, pgridx, pgridy); fitcy = griddata (proj_x, proj_y, cam_y, pgridx, pgridy); and the reverse for the camera to projector mapping Unfortunately, this code causes Labview to run out of memory on the meshgrid step (the camera is 5 megapixels, which apparently is too much for labview to handle) I then started looking through openCV, and found the cvRemap function. Unfortunately, this function takes as its starting point a regularized pixel-pixel map like the one I was trying to generate above. However, it made me hope that functions for creating such a map might be available in openCV. I couldn't find it in the openCV 1.0 API (I am stuck with 1.0 for legacy reasons), but I was hoping it's there or that someone has an easy trick. So my question is one of the following 1) How can I interpolate from scattered points to a grid in openCV; (i.e., given z = f(x,y) for scattered values of x and y, how to fill an image with f(im_x, im_y) ? 2) How can I perform an image transform that maps image 1 to image 2, given that I know a scattered mapping of points in coordinate system 1 to coordinate system 2. This could be implemented either in Labview or OpenCV. Note: I am tagging this post delaunay, because that's one method of doing a scattered interpolation, but the better tag would be "scattered interpolation"

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• DDD/NHibernate Use of Aggregate root and impact on web design - ex. Editing children of aggregate ro

  - by pbrophy

  Hopefully, this fictitious example will illustrate my problem: Suppose you are writing a system which tracks complaints for a software product, as well as many other attributes about the product. In this case the SoftwareProduct is our aggregate root and Complaints are entities that only can exist as a child of the product. In other words, if the software product is removed from the system, so shall the complaints. In the system, there is a dashboard like web page which displays many different aspects of a single SoftwareProduct. One section in the dashboard, displays a list of Complaints in a grid like fashion, showing only some very high level information for each complaint. When an admin type user chooses one of these complaints, they are directed to an edit screen which allows them to edit the detail of a single Complaint. The question is: what is the best way for the edit screen to retrieve the single Complaint, so that it can be displayed for editing purposes? Keep in mind we have already established the SoftwareProduct as an aggregate root, therefore direct access to a Complaint should not be allowed. Also, the system is using NHibernate, so eager loading is an option, but my understanding is that even if a single Complaint is eager loaded via the SoftwareProduct, as soon as the Complaints collection is accessed the rest of the collection is loaded. So, how do you get the single Complaint through the SoftwareProduct without incurring the overhead of loading the entire Complaints collection?

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• ASP.NET MVC Html Helper Extensions and Rendering Their Required "include"s

  - by Jimbo

  I have build a custom Html Helper extension as follows: public static string DatePicker(this HtmlHelper helper, string name, string value) { return string.Format(@"<script type='text/javascript'> $(document).ready(function(){{ $('#{0}').datepicker({{ changeMonth: true, changeYear:true, dateFormat: 'd-M-yy', firstDay: 1, showButtonPanel: true, showWeek: true }}); }}); </script> <input type='text' name='{0}' id='{0}' value='{1}'>", name, value); } The problem is that this now requires the page to "include" the following: <script src="/Scripts/jquery-1.4.2.min.js" type="text/javascript"></script> <script src="/Scripts/jquery.ui.datepicker.min.js" type="text/javascript"></script> And a few other items. The questions are as follows: Is there a serious processing overhead if I were to include these items in EVERY page (like in the Site.Master for example) thus negating the need for the HtmlHelper to organise the "includes" - considering there would end up being about 20 includes for all the different types of jQuery UI widgets used throughout the site. If the HtmlHelper sorts out the "includes", it will add one every time this DatePicker is used (often there are two on a page) Does anyone have a way of determining whether or not the user has already rendered the same type of control on the page, thus not re-including the same jquery libraries when multiple instances of the DatePicker (for example) are used?

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• Is Rails Metal (& Rack) a good way to implement a high traffic web service api?

  - by Greg

  I am working on a very typical web application. The main component of the user experience is a widget that a site owner would install on their front page. Every time their front page loads, the widget talks to our server and displays some of the data that returns. So there are two components to this web application: the front end UI that the site owner uses to configure their widget the back end component that responds to the widget's web api call Previously we had all of this running in PHP. Now we are experimenting with Rails, which is fantastic for #1 (the front end UI). The question is how to do #2, the back serving of widget information, efficiently. Obviously this is much higher load than the front end, since it is called every time the front page loads on one of our clients' websites. I can see two obvious approaches: A. Parallel Stack: Set up a parallel stack that uses something other than rails (e.g. our old PHP-based approach) but accesses the same database as the front end B. Rails Metal: Use Rails Metal/Rack to bypass the Rails routing mechanism, but keep the api call responder within the Rails app My main question: Is Rails/Metal a reasonable approach for something like this? But also... Will the overhead of loading the Rails environment still be too heavy? Is there a way to get even closer to the metal with Rails, bypassing most of the environment? Will Rails/Metal performance approach the perf of a similar task on straight PHP (just looking for ballpark here)? And... Is there a 'C' option that would be much better than both A and B? That is, something before going to the lengths of C code compiled to binary and installed as an nginx or apache module? Thanks in advance for any insights.

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• C# Windows Mobile 6.5 and TCP connections

  - by Phillip

  Hello, I am developing an application which makes a TCP connection out to our company server to pull down data and provide real-time data updates when the information changes. I am using the .NET Compact Framework for the development and the .NET Framework 3.5 (soon to update to 4.0) for the server-side TCP connection. I want to leave the connection open after the initial data is sent to the device from the server in order to keep the server in contact with the device should data updates need to be sent to the device. We already considered doing a WCF or connect/disconnect type of connection but we believe the overhead on the server for creating the session, transmitting and session cleanup would be unacceptable. (each device would be connecting every 60-90 seconds.) So, leaving the connection open is the best option. What I need to know is, when I leave the TCP connection open, do I need to manually transmit a heartbeat (and if so how do I do that with the .NET Compact Framework) or will the framework/stack do that for me? We have code that allows up to reconnect if the device gets disconnected (from network switching or a voice call) so that is handled. Thanks,

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• UITableViewCellSeparatorStyleNone does not hide blue separator line when selecting in UITableView

  - by clozach

  Before describing the problem, let me first point out that this is a distinct issue from this question. The Problem This screenshot was taken with a break set at tableView:didSelectRowAtIndexPath:, and as you can see in the simulator (far right of the image), there's a single-pixel blue line at the bottom of the selected cell. This is not the design asked for by the client, nor is it how this app used to behave: there should be no separator, even on selection. How I Got Here I'd initially designed this table view using custom UITableViewCell classes with corresponding nib (.xib) files and had no trouble with selections: the separator was hidden as desired. Predictably, scrolling was sluggish due to all the overhead from the view hierarchy, so I reworked the custom cells to use Loren Brichter's fast scrolling solution. Now scrolling is much faster, but I can't get rid of the separator for the life of me. What I've tried At the time of the screenshot above... the table view has "Separator [None]" in IB. the UIViewController that contains the table view has this line in viewDid Load: self.tableView.separatorStyle = UITableViewCellSeparatorStyleNone; As you can see in the screenshot, I inserted some unused lines to prove that separatorStyle is set as desired. Other testing confirms that tableView and self.tableView are equivalent pointers at that same breakpoint. I've also tried setting tableView.separatorColor to black and to clear, all with the same result: the cells look right until a selection is made.

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• using text and ntext SQL Datatypes in RPG

  - by David Stratton

  I'll preface this with saying that I'm a .NET developer, and am NOT an RPG developer. I'm working with one of our RPG developers to come up with a solution, so any suggestions you provide will get passed to him. We have a scenario where we want our iSeries to read from a SQL Server database. One of the columns is a TEXT column. IN RPG, there is no equivalent data type to use for this. We've gone back and forth on this, and our current plan is to change course, and have our SQL Server write out a text file, which the iSeries can pick up and parse. This is, however, a last resort option, as the data in the file is sensitive, and we'd like to avoid the additional security overhead. We've already got the SQL Server locked down as tight as possible (one user only has read access to this, and that user is an iSeries user.) We don't want to have to worry about transferring files back and forth. However, at this point, we see no other option. We have no in-house Java developers, and need to do this in RPG. So I'm wondering if there are any RPG developers out there who have faced this situation and have any advice.

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• People not respecting good practices at workplace

  - by VexXtreme

  Hi There are some major issues in my company regarding practices, procedures and methodologies. First of all, we're a small firm and there are only 3-4 developers, one of which is our boss who isn't really a programmer, he just chimes in now and then and tries to do code some simple things. The biggest problems are: Major cowboy coding and lack of methodologies. I've tried explaining to everyone the benefits of TDD and unit testing, but I only got weird looks as if I'm talking nonsense. Even the boss gave me the reaction along the lines of "why do we need that? it's just unnecessary overhead and a waste of time". Nobody uses design patterns. I have to tell people not to write business logic in code behind, I have to remind them not to hardcode concrete implementations and dependencies into classes and cetera. I often feel like a nazi because of this and people think I'm enforcing unnecessary policies and use of design patterns. The biggest problem of all is that people don't even respect common sense security policies. I've noticed that college students who work on tech support use our continuous integration and source control server as a dump to store their music, videos, series they download from torrents and so on. You can imagine the horror when I realized that most of the partition reserved for source control backups was used by entire seasons of TV series and movies. Our development server isn't even connected to an UPS and surge protection. It's just plugged straight into the wall outlet. I asked the boss to buy surge protection, but he said it's unnecessary. All in all, I like working here because the atmosphere is very relaxed, money is good and we're all like a family (so don't advise me to quit), but I simply don't know how to explain to people that they need to stick to some standards and good practices in IT industry and that they can't behave so irresponsibly. Thanks for the advice

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• jQuery document.ready + Asp.Net ContentPlaceholder cause Visual Studio intellisence problems

  - by Konstantin

  Hi! I want to execute JavaScript when document is ready without much syntax overhead. The idea is to use Site.Master and ContentPlaceholder: <script type="text/javascript"> $(document).ready(function () { <asp:ContentPlaceHolder ID="OnReadyScript" runat="server" /> }); </script> and in inherited pages just write plain code: <asp:Content ID="Content3" ContentPlaceHolderID="OnReadyScript" runat="server"> $("#Login").focus(); </asp:Content> It works fine but Visual Studio complains and gives warnings. Warning in master page is Expected expression at the line <asp:ContentPlaceHolder. In inherited pages warning is Could not find 'OnReadyScript' in the current master page or pages. I tried using Writer.Write in master page to render script tag and wrapping code: <% Writer.Write(@"<script type=""text/javascript"">$(document).ready(function () {"); %> <asp:ContentPlaceHolder ID="OnReadyScrit" runat="server" /> <% Writer.Write(@"});"); %> but page rendering terminates after opening script tag is rendered. Html basically ends with <script type="text/javascript"> How can I make it work?

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• How to resize image to fit UITableView cell?

  - by stefanB

  How to fit UIImage into the cell of UITableView, UITableViewCell (?). Do you addSubview to cell or is there a way to resize cell.image or the UIImage before it is assigned to cell.image ? I want to keep the cell size default (whatever it is when you init with zero rectangle) and would like to add icon like pictures to each entry. Images are slightly bigger than the cell size (table row size). I think the code looks like this (from top of my head): UIImage * image = [[UIImage alloc] imageWithName:@"bart.jpg"]; cell = ... dequeue cell in UITableView data source (UITableViewController ...) cell.text = @"bart"; cell.image = image; What do I need to do to resize the image to fit the cell size? I've seen something like: UIImageView * iview = [[UIImageView alloc] initWithImage:image]; iview.frame = CGRectMake(...); // or something similar [cell.contentView addSubview:iview] The above will add image to cell and I can calculate the size to fit it, however: I'm not sure if there is a better way, isn't it too much overhead to add UIImageView just to resize the cell.image ? Now my label (cell.text) needs to be moved as it is obscured by image, I've seen a solution where you just add the text as a label: Example: UILabel * text = [[UILable alloc] init]; text.text = @"bart"; [cell.contentView addSubview:iview]; [cell.contentView addSubview:label]; // not sure if this will position the text next to the label // edited original example had [cell addSubview:label], maybe that's the problem Could someone point me in correct direction? EDIT: Doh [cell.contentview addSubview:view] not [cell addSubview:view] maybe I'm supposed to look at this: - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { UITableViewCell *cell = ...; CGRect frame = cell.contentView.bounds; UILabel *myLabel = [[UILabel alloc] initWithFrame:frame]; myLabel.text = ...; [cell.contentView addSubview:myLabel]; [myLabel release]; }

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• DDD: Aggregate Roots

  - by Mosh

  Hello, I need help with finding my aggregate root and boundary. I have 3 Entities: Plan, PlannedRole and PlannedTraining. Each Plan can include many PlannedRoles and PlannedTrainings. Solution 1: At first I thought Plan is the aggregate root because PlannedRole and PlannedTraining do not make sense out of the context of a Plan. They are always within a plan. Also, we have a business rule that says each Plan can have a maximum of 3 PlannedRoles and 5 PlannedTrainings. So I thought by nominating the Plan as the aggregate root, I can enforce this invariant. However, we have a Search page where the user searches for Plans. The results shows a few properties of the Plan itself (and none of its PlannedRoles or PlannedTrainings). I thought if I have to load the entire aggregate, it would have a lot of overhead. There are nearly 3000 plans and each may have a few children. Loading all these objects together and then ignoring PlannedRoles and PlannedTrainings in the search page doesn't make sense to me. Solution 2: I just realized the user wants 2 more search pages where they can search for Planned Roles or Planned Trainings. That made me realize they are trying to access these objects independently and "out of" the context of Plan. So I thought I was wrong about my initial design and that is how I came up with this solution. So, I thought to have 3 aggregates here, 1 for each Entity. This approach enables me to search for each Entity independently and also resolves the performance issue in solution 1. However, using this approach I cannot enforce the invariant I mentioned earlier. There is also another invariant that states a Plan can be changed only if it is of a certain status. So, I shouldn't be able to add any PlannedRoles or PlannedTrainings to a Plan that is not in that status. Again, I can't enforce this invariant with the second approach. Any advice would be greatly appreciated. Cheers, Mosh

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• Is there any better IDOMImplementation other than MSXML?

  - by Chau Chee Yang

  There are 3 IDOMImplementation available in Delphi: MSXML Xerces XML ADOM XML v4 MSXML is the default IDOMImplementation. My test is count the time need to load a 10MB xml file. I use a Delphi unit generated from a XSD using XML data binding to load the xml file. This unit has 3 common function: function Getmenubar(Doc: IXMLDocument): IXMLMenubarType; function Loadmenubar(const FileName: WideString): IXMLMenubarType; function Newmenubar: IXMLMenubarType; I learn from the web that some comment that MSXML's overhead is high that it doesn't perform if compare to other XML parser. However, my study shows that MSXML is the best among others. Xerces XML 2nd and ADOM XML v4 the worst: MSXML - 0.6410 seconds Xerces XML - 2.4220 seconds ADOM XML v4 - 67.50 seconds I also come across with OmniXML that claim to have much better performance compare to MSXML but I never success using it with the unit generated by XML data binding. Is there any other vendor that implement IDOMImplementation of Delphi that work much better than MSXML? I am using Delphi 2010 and Windows 7.

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• Creating A Single Generic Handler For Agatha?

  - by David

  I'm using the Agatha request/response library (and StructureMap, as utilized by Agatha 1.0.5.0) for a service layer that I'm prototyping, and one thing I've noticed is the large number of handlers that need to be created. It generally makes sense that any request/response type pair would need their own handler. However, as this scales to a large enterprise environment that's going to be A LOT of handlers. What I've started doing is dividing up the enterprise domain into logical processor classes (dozens of processors instead of many hundreds or possibly eventually thousands handlers). The convention is that each request/response type (all of which inherit from a domain base request/response pair, which inherit from Agatha's) gets exactly one function in a processor somewhere. The generic handler (which inherits from Agatha's RequestHandler) then uses reflection in the Handle method to find the method for the given TREQUEST/TRESPONSE and invoke it. If it can't find one or if it finds more than one, it returns a TRESPONSE containing an error message (messages are standardized in the domain's base response class). The goal here is to allow developers across the enterprise to just concern themselves with writing their request/response types and processor functions in the domain and not have to spend additional overhead creating handler classes which would all do exactly the same thing (pass control to a processor function). However, it seems that I still need to have defined a handler class (albeit empty, since the base handler takes care of everything) for each request/response type pair. Otherwise, the following exception is thrown when dispatching a request to the service: StructureMap Exception Code: 202 No Default Instance defined for PluginFamily Agatha.ServiceLayer.IRequestHandler`1[[TSFG.Domain.DTO.Actions.HelloWorldRequest, TSFG.Domain.DTO, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]], Agatha.ServiceLayer, Version=1.0.5.0, Culture=neutral, PublicKeyToken=6f21cf452a4ffa13 Is there a way that I'm not seeing to tell StructureMap and/or Agatha to always use the base handler class for all request/response type pairs? Or maybe to use Reflection.Emit to generate empty handlers in memory at application start just to satisfy the requirement? I'm not 100% familiar with these libraries and am learning as I go along, but so far my attempts at both those possible approaches have been unsuccessful. Can anybody offer some advice on solving this, or perhaps offer another approach entirely?

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