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  • Why Does Ejabberd Start Fail?

    - by Andrew
    I am trying to install ejabberd 2.1.10-2 on my Ubuntu 12.04.1 server. This is a fresh install, and ejabberd is never successfully installed. The Install Every time, apt-get hangs on this: Setting up ejabberd (2.1.10-2ubuntu1) ... Generating SSL certificate /etc/ejabberd/ejabberd.pem... Creating config file /etc/ejabberd/ejabberd.cfg with new version Starting jabber server: ejabberd............................................................ failed. The dots just go forever until it times out or I 'killall' beam, beam.smp, epmd, and ejabberd processes. I've turned off all firewall restrictions. Here's the output of epmd -names while the install is hung: epmd: up and running on port 4369 with data: name ejabberdctl at port 42108 name ejabberd at port 39621 And after it fails: epmd: up and running on port 4369 with data: name ejabberd at port 39621 At the same time (during and after), the output of both netstat -atnp | grep 5222 and netstat -atnp | grep 5280 is empty. The Crash File A crash dump file is create at /var/log/ejabber/erl_crash.dump. The slogan (i.e. reason for the crash) is: Slogan: Kernel pid terminated (application_controller) ({application_start_failure,kernel,{shutdown,{kernel,start,[normal,[]]}}}) It's alive? Whenever I try to relaunch ejabberd with service ejabberd start, the same thing happens - even if I've killed all processes before doing so. However, when I killall the processes listed above again, and run su - ejabberd -c /usr/sbin/ejabberd, this is the output I get: Erlang R14B04 (erts-5.8.5) [source] [64-bit] [rq:1] [async-threads:0] [kernel-poll:false] Eshell V5.8.5 (abort with ^G) (ejabberd@ns1)1> =INFO REPORT==== 15-Oct-2012::12:26:13 === I(<0.478.0>:ejabberd_listener:166) : Reusing listening port for 5222 =INFO REPORT==== 15-Oct-2012::12:26:13 === I(<0.479.0>:ejabberd_listener:166) : Reusing listening port for 5269 =INFO REPORT==== 15-Oct-2012::12:26:13 === I(<0.480.0>:ejabberd_listener:166) : Reusing listening port for 5280 =INFO REPORT==== 15-Oct-2012::12:26:13 === I(<0.40.0>:ejabberd_app:72) : ejabberd 2.1.10 is started in the node ejabberd@ns1 Then, the server appears to be running. I get a login prompt when I access http://mydomain.com:5280/admin/. Of course I can't login unless I create an account. At this time, the output of netstat -atnp | grep 5222 and netstat -atnp | grep 5280 is as follows: tcp 0 0 0.0.0.0:5222 0.0.0.0:* LISTEN 19347/beam tcp 0 0 0.0.0.0:5280 0.0.0.0:* LISTEN 19347/beam ejabberdctl Even when it appears ejabberd is running, trying to do anything with ejabberdctl fails. For example: trying to register a user: root@ns1:~# ejabberdctl register myusername mydomain.com mypassword Failed RPC connection to the node ejabberd@ns1: nodedown I have no idea what I'm doing wrong. This happens on two different servers I have with identical software installed (really not much of anything). Please help. Thanks.

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  • Texture mapping on gluDisk

    - by Marnix
    I'm trying to map a brick texture on the edge of a fountain and I'm using gluDisk for that. How can I make the right coordinates for the disk? My code looks like this and I have only found a function that takes the texture along with the camera. I want the cubic texture to be alongside of the fountain, but gluDisk does a linear mapping. How do I get a circular mapping? void Fountain::Draw() { glPushMatrix(); // push 1 this->ApplyWorldMatrixGL(); glEnable(GL_TEXTURE_2D); // enable texturing glPushMatrix(); // push 2 glRotatef(90,-1,0,0); // rotate 90 for the quadric // also drawing more here... // stone texture glBindTexture(GL_TEXTURE_2D, texIDs[0]); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT); glPushMatrix(); // push 3 glTranslatef(0,0,height); // spherical texture generation // this piece of code doesn't work as I intended glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP); glTexGeni(GL_T, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP); glEnable(GL_TEXTURE_GEN_S); glEnable(GL_TEXTURE_GEN_T); GLUquadric *tub = gluNewQuadric(); gluQuadricTexture(tub, GL_TRUE); gluDisk(tub, radius, outerR, nrVertices, nrVertices); gluDeleteQuadric(tub); glDisable(GL_TEXTURE_GEN_S); glDisable(GL_TEXTURE_GEN_T); glPopMatrix(); // pop 3 // more drawing here... glPopMatrix(); // pop 2 // more drawing here... glPopMatrix(); // pop 1 } To refine my question a bit. This is an image of what it is at default (left) and of what I want (right). The texture should fit in the border of the disk, a lot of times. If this is possible with the texture matrix, than that's fine with me as well.

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  • top tweets SOA Partner Community – June 2013

    - by JuergenKress
    Send your tweets @soacommunity #soacommunity and follow us at http://twitter.com/soacommunity Oracle SOA Learn how Business Rules are used in Oracle SOA Suite. New free self-study course - Oracle Univ. #soa #oraclesoa http://pub.vitrue.com/ll9B OPITZ CONSULTING ?Wie #BPM und #SOA zusammengehören? Watch 100-Seconds-Video-Lesson by @Rolfbaer - http://ow.ly/luSjK @soacommunity Andrejus Baranovskis ?Customized BPM 11g PS6 Workspace Application http://fb.me/2ukaSBXKs Mark Nelson ?Case Management Samples Released http://wp.me/pgVeO-Lv Mark Nelson Instance Patching Demo for BPM 11.1.1.7 http://wp.me/pgVeO-Lx Simone Geib Antony Reynolds: Target Verification #oraclesoa https://blogs.oracle.com/reynolds/ OPITZ CONSULTING ?"It's all about Integration - Developing with Oracle #Cloud Services" @t_winterberg files: http://ow.ly/ljtEY #cloudworld @soacommunity Arun Pareek ?Functional Testing Business Processes In Oracle BPM Suite 11g http://wp.me/pkPu1-pc via @arrunpareek SOA Proactive Want to get started with Human Workflow? Check out the introductory video on OTN, http://pub.vitrue.com/enIL C2B2 Consulting Free tech workshop,London 6th of Jun Diagnosing Performance & Scalability Problems in Oracle SOASuite http://www.c2b2.co.uk/oracle_fusion_middleware_performance_seminar … @soacommunity Oracle BPM Must have technologies for delivering effective #CX : #BPM #Social #Mobile > #OracleBPM Whitepaper http://pub.vitrue.com/6pF6 OracleBlogs ?Introduction to Web Forms -Basic Tutorial http://ow.ly/2wQLTE OTNArchBeat ?Complete State of SOA podcast now available w/ @soacommunity @hajonormann @gschmutz @t_winterberg #industrialsoa http://pub.vitrue.com/PZFw Ronald Luttikhuizen VENNSTER Blog | Article published - Fault Handling and Prevention - Part 2 | http://blog.vennster.nl/2013/05/article-published-fault-handling-and.html … Mark Nelson ?Getting to know Maven http://wp.me/pgVeO-Lk gschmutz ?Cool! Our 2nd article has just been published: "Fault Handling and Prevention for Services in Oracle Service Bus" http://pub.vitrue.com/jMOy David Shaffer Interesting SOA Development and Delivery post on A-Team Redstack site - http://bit.ly/18oqrAI . Would be great to get others to contribute! Mark Nelson BPM PS6 video showing process lifecycle in more detail (30min) http://wp.me/pgVeO-Ko SOA Proactive ?Webcast: 'Introduction and Troubleshooting of the SOA 11g Database Adapter', May 9th. Register now at http://pub.vitrue.com/8In7 Mark Nelson ?SOA Development and Delivery http://wp.me/pgVeO-Kd Oracle BPM Manoj Das, VP Product Mangement talks about new #OracleBPM release #BPM #processmanagement http://pub.vitrue.com/FV3R OTNArchBeat Podcast: The State of SOA w/ @soacommunity @hajonormann @gschmutz @t_winterberg #industrialsoa http://pub.vitrue.com/OK2M gschmutz New article series on Industrial SOA started on OTN and Service Technology Magazine: http://guidoschmutz.wordpress.com/2013/04/22/first-two-chapters-of-industrial-soa-articles-series-have-been-published-both-on-otn-and-service-technology-magazine/ … #industrialSOA Danilo Schmiedel ?Article series #industrialSOA published on OTN and Service Technology Magazine http://inside-bpm-and-soa.blogspot.de/2013/04/industrial-soa_22.html … @soacommunity @OC_WIRE SOA & BPM Partner Community For regular information on Oracle SOA Suite become a member in the SOA & BPM Partner Community for registration please visit www.oracle.com/goto/emea/soa (OPN account required) If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Facebook Wiki Mix Forum Technorati Tags: twitter,SOA Community,Oracle SOA,Oracle BPM,Community,OPN,Jürgen Kress

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  • Advice Needed: Developers blocked by waiting on code to merge from another branch using GitFlow

    - by fogwolf
    Our team just made the switch from FogBugz & Kiln/Mercurial to Jira & Stash/Git. We are using the Git Flow model for branching, adding subtask branches off of feature branches (relating to Jira subtasks of Jira features). We are using Stash to assign a reviewer when we create a pull request to merge back into the parent branch (usually develop but for subtasks back into the feature branch). The problem we're finding is that even with the best planning and breakdown of feature cases, when multiple developers are working together on the same feature, say on the front-end and back-end, if they are working on interdependent code that is in separate branches one developer ends up blocking the other. We've tried pulling between each others' branches as we develop. We've also tried creating local integration branches each developer can pull from multiple branches to test the integration as they develop. Finally, and this seems to work possibly the best for us so far, though with a bit more overhead, we have tried creating an integration branch off of the feature branch right off the bat. When a subtask branch (off of the feature branch) is ready for a pull request and code review, we also manually merge those change sets into this feature integration branch. Then all interested developers are able to pull from that integration branch into other dependent subtask branches. This prevents anyone from waiting for any branch they are dependent upon to pass code review. I know this isn't necessarily a Git issue - it has to do with working on interdependent code in multiple branches, mixed with our own work process and culture. If we didn't have the strict code-review policy for develop (true integration branch) then developer 1 could merge to develop for developer 2 to pull from. Another complication is that we are also required to do some preliminary testing as part of the code review process before handing the feature off to QA.This means that even if front-end developer 1 is pulling directly from back-end developer 2's branch as they go, if back-end developer 2 finishes and his/her pull request is sitting in code review for a week, then front-end developer 2 technically can't create his pull request/code review because his/her code reviewer can't test because back-end developer 2's code hasn't been merged into develop yet. Bottom line is we're finding ourselves in a much more serial rather than parallel approach in these instance, depending on which route we go, and would like to find a process to use to avoid this. Last thing I'll mention is we realize by sharing code across branches that haven't been code reviewed and finalized yet we are in essence using the beta code of others. To a certain extent I don't think we can avoid that and are willing to accept that to a degree. Anyway, any ideas, input, etc... greatly appreciated. Thanks!

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  • SQLAuthority News – Presented Soft Skill Session on Presentation Skills at SQL Bangalore on May 3, 2014

    - by Pinal Dave
    I have presented on various database technologies for almost 10 years now. SQL, Database and NoSQL have been part of my life. Earlier this month, I had the opportunity to present on the topic Performing an Effective Presentation. I must say it was blast to prepare as well as present this session. This event was part of the SQL Bangalore community. If you are in Bangalore, you must be part of this group. SQL Bangalore is a wonderful community and we always have a great response when we present on technology. It is SQL User Group and we discuss everything SQL there. This month we had SQL Server 2014 theme and we had a community launch of SQL Server. We have the best of the best speakers presenting on SQL Server 2014 technology. The event had amazing speakers and each of them did justice to the subject. You can read about this over here. In this session I told a story from my life. I talked about who inspired me and how I learned to speak in public. I told stories about two legends  who have inspired me. There is no video recording of this session. If you want to get resources from this session, please sign up my newsletter at http://bit.ly/sqllearn. Well, I had a great time at this event. We had over 250 people showed up at this event and had a grand  time together. I personally enjoyed a session of Amit Benerjee, Balmukund Lakhani and Vinod Kumar. Ken and Surabh also entertained the audience. Overall, this was a grand event and if you were in Bangalore and did not make it to this event. You did miss out on a few things. Here are a few photos of this event. SQL Bangalore UG Nupur, Chandra, Shaivi, Balmukund, Amit, Vinod [captions This] SQL Bangalore UG Audience Pinal Dave presenting at SQL UG in Bangalore Here are few of the slides from this presentation: Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, SQLAuthority News, T SQL

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  • NYC Silverlight FireStarter - June 5th 2010 at the NYC Microsoft Office

    - by Sam Abraham
    On Saturday June 5th, 2010, I spent my Saturday morning at the NYC Silverlight FireStarter. Presenting was Peter Laudati from Microsoft and Jason Beres, Matt Van Horn and Todd Snyder from Infragistics. I watched the Simulcast for the morning sessions as I was tied up with some work, but ended up finally making it to the Microsoft Office and had the opportunity to attend the last hour of the event in person.   For me, the quality of the Simulcast was as good as in-person attendance so far as sound/video quality and the interaction with speakers. In the background was a screen with tweets from remote attendees asking questions or commenting on the presentations. Presenters did periodically stop to answer the tweeted questions as well as questions from attendees. Only thing I missed was getting my hands on some of that swag that was (literally) flying in the air at the event floor.   Upon my arrival at the Microsoft Office Location in NYC, I spoke with Rachel Appel and Peter Laudati asking for permission to take a few photos to record the outstanding effort that took place in putting this event together. Both agreed and I started with putting my photography skills to work.   You can always gauge the quality of an event with the number of its attendees who opt to stay till the last minute as well as the level of interaction of the audience with the speaker. With most of the FireStarter attendees remaining till the very end of the talk, and with the many questions that were asked, one can simply judge the event as a success as per my aforementioned criteria.   Evaluation forms were passed around and Peter strongly encouraged the audience to openly speak their mind as they record their comments. I didn't get to submit my evaluation as I was busy recording the event in photos, so here it goes: I believe that lots of hard work was put into making this event a reality. Quality of speakers, topics and level of Geekiness at the event was outstanding.  Overall, aside from a minor issue with Lunch delivery time, this event was of high quality and I am very sure everyone's evaluation will be in line with my analysis of it being a great success. Below are a few photos of the event.   --Sam Abraham Site Director - West Palm Beach .Net User Group www.Fladotnet.com     NYC Silverlight FireStarter Speakers - From Left to right: Peter Laudati, Todd Snyder, Matt Van Horn & Jason Beres   As jason wasn't quiet visible in the above photo, a closeup was taken (It was Jason's birthday and he had to leave a bit early, so the Infagisticts team thought outside the box...)     Full Room - That was at the last hour of the event   Another view of full room   Discussions during the break   End-of-event Raffle

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  • PTLQueue : a scalable bounded-capacity MPMC queue

    - by Dave
    Title: Fast concurrent MPMC queue -- I've used the following concurrent queue algorithm enough that it warrants a blog entry. I'll sketch out the design of a fast and scalable multiple-producer multiple-consumer (MPSC) concurrent queue called PTLQueue. The queue has bounded capacity and is implemented via a circular array. Bounded capacity can be a useful property if there's a mismatch between producer rates and consumer rates where an unbounded queue might otherwise result in excessive memory consumption by virtue of the container nodes that -- in some queue implementations -- are used to hold values. A bounded-capacity queue can provide flow control between components. Beware, however, that bounded collections can also result in resource deadlock if abused. The put() and take() operators are partial and wait for the collection to become non-full or non-empty, respectively. Put() and take() do not allocate memory, and are not vulnerable to the ABA pathologies. The PTLQueue algorithm can be implemented equally well in C/C++ and Java. Partial operators are often more convenient than total methods. In many use cases if the preconditions aren't met, there's nothing else useful the thread can do, so it may as well wait via a partial method. An exception is in the case of work-stealing queues where a thief might scan a set of queues from which it could potentially steal. Total methods return ASAP with a success-failure indication. (It's tempting to describe a queue or API as blocking or non-blocking instead of partial or total, but non-blocking is already an overloaded concurrency term. Perhaps waiting/non-waiting or patient/impatient might be better terms). It's also trivial to construct partial operators by busy-waiting via total operators, but such constructs may be less efficient than an operator explicitly and intentionally designed to wait. A PTLQueue instance contains an array of slots, where each slot has volatile Turn and MailBox fields. The array has power-of-two length allowing mod/div operations to be replaced by masking. We assume sensible padding and alignment to reduce the impact of false sharing. (On x86 I recommend 128-byte alignment and padding because of the adjacent-sector prefetch facility). Each queue also has PutCursor and TakeCursor cursor variables, each of which should be sequestered as the sole occupant of a cache line or sector. You can opt to use 64-bit integers if concerned about wrap-around aliasing in the cursor variables. Put(null) is considered illegal, but the caller or implementation can easily check for and convert null to a distinguished non-null proxy value if null happens to be a value you'd like to pass. Take() will accordingly convert the proxy value back to null. An advantage of PTLQueue is that you can use atomic fetch-and-increment for the partial methods. We initialize each slot at index I with (Turn=I, MailBox=null). Both cursors are initially 0. All shared variables are considered "volatile" and atomics such as CAS and AtomicFetchAndIncrement are presumed to have bidirectional fence semantics. Finally T is the templated type. I've sketched out a total tryTake() method below that allows the caller to poll the queue. tryPut() has an analogous construction. Zebra stripping : alternating row colors for nice-looking code listings. See also google code "prettify" : https://code.google.com/p/google-code-prettify/ Prettify is a javascript module that yields the HTML/CSS/JS equivalent of pretty-print. -- pre:nth-child(odd) { background-color:#ff0000; } pre:nth-child(even) { background-color:#0000ff; } border-left: 11px solid #ccc; margin: 1.7em 0 1.7em 0.3em; background-color:#BFB; font-size:12px; line-height:65%; " // PTLQueue : Put(v) : // producer : partial method - waits as necessary assert v != null assert Mask = 1 && (Mask & (Mask+1)) == 0 // Document invariants // doorway step // Obtain a sequence number -- ticket // As a practical concern the ticket value is temporally unique // The ticket also identifies and selects a slot auto tkt = AtomicFetchIncrement (&PutCursor, 1) slot * s = &Slots[tkt & Mask] // waiting phase : // wait for slot's generation to match the tkt value assigned to this put() invocation. // The "generation" is implicitly encoded as the upper bits in the cursor // above those used to specify the index : tkt div (Mask+1) // The generation serves as an epoch number to identify a cohort of threads // accessing disjoint slots while s-Turn != tkt : Pause assert s-MailBox == null s-MailBox = v // deposit and pass message Take() : // consumer : partial method - waits as necessary auto tkt = AtomicFetchIncrement (&TakeCursor,1) slot * s = &Slots[tkt & Mask] // 2-stage waiting : // First wait for turn for our generation // Acquire exclusive "take" access to slot's MailBox field // Then wait for the slot to become occupied while s-Turn != tkt : Pause // Concurrency in this section of code is now reduced to just 1 producer thread // vs 1 consumer thread. // For a given queue and slot, there will be most one Take() operation running // in this section. // Consumer waits for producer to arrive and make slot non-empty // Extract message; clear mailbox; advance Turn indicator // We have an obvious happens-before relation : // Put(m) happens-before corresponding Take() that returns that same "m" for T v = s-MailBox if v != null : s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 // unlock slot to admit next producer and consumer return v Pause tryTake() : // total method - returns ASAP with failure indication for auto tkt = TakeCursor slot * s = &Slots[tkt & Mask] if s-Turn != tkt : return null T v = s-MailBox // presumptive return value if v == null : return null // ratify tkt and v values and commit by advancing cursor if CAS (&TakeCursor, tkt, tkt+1) != tkt : continue s-MailBox = null ST-ST barrier s-Turn = tkt + Mask + 1 return v The basic idea derives from the Partitioned Ticket Lock "PTL" (US20120240126-A1) and the MultiLane Concurrent Bag (US8689237). The latter is essentially a circular ring-buffer where the elements themselves are queues or concurrent collections. You can think of the PTLQueue as a partitioned ticket lock "PTL" augmented to pass values from lock to unlock via the slots. Alternatively, you could conceptualize of PTLQueue as a degenerate MultiLane bag where each slot or "lane" consists of a simple single-word MailBox instead of a general queue. Each lane in PTLQueue also has a private Turn field which acts like the Turn (Grant) variables found in PTL. Turn enforces strict FIFO ordering and restricts concurrency on the slot mailbox field to at most one simultaneous put() and take() operation. PTL uses a single "ticket" variable and per-slot Turn (grant) fields while MultiLane has distinct PutCursor and TakeCursor cursors and abstract per-slot sub-queues. Both PTL and MultiLane advance their cursor and ticket variables with atomic fetch-and-increment. PTLQueue borrows from both PTL and MultiLane and has distinct put and take cursors and per-slot Turn fields. Instead of a per-slot queues, PTLQueue uses a simple single-word MailBox field. PutCursor and TakeCursor act like a pair of ticket locks, conferring "put" and "take" access to a given slot. PutCursor, for instance, assigns an incoming put() request to a slot and serves as a PTL "Ticket" to acquire "put" permission to that slot's MailBox field. To better explain the operation of PTLQueue we deconstruct the operation of put() and take() as follows. Put() first increments PutCursor obtaining a new unique ticket. That ticket value also identifies a slot. Put() next waits for that slot's Turn field to match that ticket value. This is tantamount to using a PTL to acquire "put" permission on the slot's MailBox field. Finally, having obtained exclusive "put" permission on the slot, put() stores the message value into the slot's MailBox. Take() similarly advances TakeCursor, identifying a slot, and then acquires and secures "take" permission on a slot by waiting for Turn. Take() then waits for the slot's MailBox to become non-empty, extracts the message, and clears MailBox. Finally, take() advances the slot's Turn field, which releases both "put" and "take" access to the slot's MailBox. Note the asymmetry : put() acquires "put" access to the slot, but take() releases that lock. At any given time, for a given slot in a PTLQueue, at most one thread has "put" access and at most one thread has "take" access. This restricts concurrency from general MPMC to 1-vs-1. We have 2 ticket locks -- one for put() and one for take() -- each with its own "ticket" variable in the form of the corresponding cursor, but they share a single "Grant" egress variable in the form of the slot's Turn variable. Advancing the PutCursor, for instance, serves two purposes. First, we obtain a unique ticket which identifies a slot. Second, incrementing the cursor is the doorway protocol step to acquire the per-slot mutual exclusion "put" lock. The cursors and operations to increment those cursors serve double-duty : slot-selection and ticket assignment for locking the slot's MailBox field. At any given time a slot MailBox field can be in one of the following states: empty with no pending operations -- neutral state; empty with one or more waiting take() operations pending -- deficit; occupied with no pending operations; occupied with one or more waiting put() operations -- surplus; empty with a pending put() or pending put() and take() operations -- transitional; or occupied with a pending take() or pending put() and take() operations -- transitional. The partial put() and take() operators can be implemented with an atomic fetch-and-increment operation, which may confer a performance advantage over a CAS-based loop. In addition we have independent PutCursor and TakeCursor cursors. Critically, a put() operation modifies PutCursor but does not access the TakeCursor and a take() operation modifies the TakeCursor cursor but does not access the PutCursor. This acts to reduce coherence traffic relative to some other queue designs. It's worth noting that slow threads or obstruction in one slot (or "lane") does not impede or obstruct operations in other slots -- this gives us some degree of obstruction isolation. PTLQueue is not lock-free, however. The implementation above is expressed with polite busy-waiting (Pause) but it's trivial to implement per-slot parking and unparking to deschedule waiting threads. It's also easy to convert the queue to a more general deque by replacing the PutCursor and TakeCursor cursors with Left/Front and Right/Back cursors that can move either direction. Specifically, to push and pop from the "left" side of the deque we would decrement and increment the Left cursor, respectively, and to push and pop from the "right" side of the deque we would increment and decrement the Right cursor, respectively. We used a variation of PTLQueue for message passing in our recent OPODIS 2013 paper. ul { list-style:none; padding-left:0; padding:0; margin:0; margin-left:0; } ul#myTagID { padding: 0px; margin: 0px; list-style:none; margin-left:0;} -- -- There's quite a bit of related literature in this area. I'll call out a few relevant references: Wilson's NYU Courant Institute UltraComputer dissertation from 1988 is classic and the canonical starting point : Operating System Data Structures for Shared-Memory MIMD Machines with Fetch-and-Add. Regarding provenance and priority, I think PTLQueue or queues effectively equivalent to PTLQueue have been independently rediscovered a number of times. See CB-Queue and BNPBV, below, for instance. But Wilson's dissertation anticipates the basic idea and seems to predate all the others. Gottlieb et al : Basic Techniques for the Efficient Coordination of Very Large Numbers of Cooperating Sequential Processors Orozco et al : CB-Queue in Toward high-throughput algorithms on many-core architectures which appeared in TACO 2012. Meneghin et al : BNPVB family in Performance evaluation of inter-thread communication mechanisms on multicore/multithreaded architecture Dmitry Vyukov : bounded MPMC queue (highly recommended) Alex Otenko : US8607249 (highly related). John Mellor-Crummey : Concurrent queues: Practical fetch-and-phi algorithms. Technical Report 229, Department of Computer Science, University of Rochester Thomasson : FIFO Distributed Bakery Algorithm (very similar to PTLQueue). Scott and Scherer : Dual Data Structures I'll propose an optimization left as an exercise for the reader. Say we wanted to reduce memory usage by eliminating inter-slot padding. Such padding is usually "dark" memory and otherwise unused and wasted. But eliminating the padding leaves us at risk of increased false sharing. Furthermore lets say it was usually the case that the PutCursor and TakeCursor were numerically close to each other. (That's true in some use cases). We might still reduce false sharing by incrementing the cursors by some value other than 1 that is not trivially small and is coprime with the number of slots. Alternatively, we might increment the cursor by one and mask as usual, resulting in a logical index. We then use that logical index value to index into a permutation table, yielding an effective index for use in the slot array. The permutation table would be constructed so that nearby logical indices would map to more distant effective indices. (Open question: what should that permutation look like? Possibly some perversion of a Gray code or De Bruijn sequence might be suitable). As an aside, say we need to busy-wait for some condition as follows : "while C == 0 : Pause". Lets say that C is usually non-zero, so we typically don't wait. But when C happens to be 0 we'll have to spin for some period, possibly brief. We can arrange for the code to be more machine-friendly with respect to the branch predictors by transforming the loop into : "if C == 0 : for { Pause; if C != 0 : break; }". Critically, we want to restructure the loop so there's one branch that controls entry and another that controls loop exit. A concern is that your compiler or JIT might be clever enough to transform this back to "while C == 0 : Pause". You can sometimes avoid this by inserting a call to a some type of very cheap "opaque" method that the compiler can't elide or reorder. On Solaris, for instance, you could use :"if C == 0 : { gethrtime(); for { Pause; if C != 0 : break; }}". It's worth noting the obvious duality between locks and queues. If you have strict FIFO lock implementation with local spinning and succession by direct handoff such as MCS or CLH,then you can usually transform that lock into a queue. Hidden commentary and annotations - invisible : * And of course there's a well-known duality between queues and locks, but I'll leave that topic for another blog post. * Compare and contrast : PTLQ vs PTL and MultiLane * Equivalent : Turn; seq; sequence; pos; position; ticket * Put = Lock; Deposit Take = identify and reserve slot; wait; extract & clear; unlock * conceptualize : Distinct PutLock and TakeLock implemented as ticket lock or PTL Distinct arrival cursors but share per-slot "Turn" variable provides exclusive role-based access to slot's mailbox field put() acquires exclusive access to a slot for purposes of "deposit" assigns slot round-robin and then acquires deposit access rights/perms to that slot take() acquires exclusive access to slot for purposes of "withdrawal" assigns slot round-robin and then acquires withdrawal access rights/perms to that slot At any given time, only one thread can have withdrawal access to a slot at any given time, only one thread can have deposit access to a slot Permissible for T1 to have deposit access and T2 to simultaneously have withdrawal access * round-robin for the purposes of; role-based; access mode; access role mailslot; mailbox; allocate/assign/identify slot rights; permission; license; access permission; * PTL/Ticket hybrid Asymmetric usage ; owner oblivious lock-unlock pairing K-exclusion add Grant cursor pass message m from lock to unlock via Slots[] array Cursor performs 2 functions : + PTL ticket + Assigns request to slot in round-robin fashion Deconstruct protocol : explication put() : allocate slot in round-robin fashion acquire PTL for "put" access store message into slot associated with PTL index take() : Acquire PTL for "take" access // doorway step seq = fetchAdd (&Grant, 1) s = &Slots[seq & Mask] // waiting phase while s-Turn != seq : pause Extract : wait for s-mailbox to be full v = s-mailbox s-mailbox = null Release PTL for both "put" and "take" access s-Turn = seq + Mask + 1 * Slot round-robin assignment and lock "doorway" protocol leverage the same cursor and FetchAdd operation on that cursor FetchAdd (&Cursor,1) + round-robin slot assignment and dispersal + PTL/ticket lock "doorway" step waiting phase is via "Turn" field in slot * PTLQueue uses 2 cursors -- put and take. Acquire "put" access to slot via PTL-like lock Acquire "take" access to slot via PTL-like lock 2 locks : put and take -- at most one thread can access slot's mailbox Both locks use same "turn" field Like multilane : 2 cursors : put and take slot is simple 1-capacity mailbox instead of queue Borrow per-slot turn/grant from PTL Provides strict FIFO Lock slot : put-vs-put take-vs-take at most one put accesses slot at any one time at most one put accesses take at any one time reduction to 1-vs-1 instead of N-vs-M concurrency Per slot locks for put/take Release put/take by advancing turn * is instrumental in ... * P-V Semaphore vs lock vs K-exclusion * See also : FastQueues-excerpt.java dice-etc/queue-mpmc-bounded-blocking-circular-xadd/ * PTLQueue is the same as PTLQB - identical * Expedient return; ASAP; prompt; immediately * Lamport's Bakery algorithm : doorway step then waiting phase Threads arriving at doorway obtain a unique ticket number Threads enter in ticket order * In the terminology of Reed and Kanodia a ticket lock corresponds to the busy-wait implementation of a semaphore using an eventcount and a sequencer It can also be thought of as an optimization of Lamport's bakery lock was designed for fault-tolerance rather than performance Instead of spinning on the release counter, processors using a bakery lock repeatedly examine the tickets of their peers --

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  • The best Bar on the globe is ... in Seoul/Korea

    - by Mike Dietrich
    As you know already sometimes I write about things which really don't have to do anything with a database upgrade. So if you are looking for tips and tricks and articles about that topic please stop reading now Actually I'm not a lets-go-to-a-bar person. I enjoy good food and a fine dessert wine afterwards. But last week in Seoul/Korea Ryan, our local host, did ask us after a wonderful dinner at a Korean Barbecue place if we'd like to visit a bar. I was really tired as I flew into Seoul overnight from Sunday to Monday arriving Monday early morning, getting shower, breakfast - and then a full day of very good and productive customer meetings. But one thing Ryan mentioned catched my immediate attention: The owner of the bar collects records and has a huge tube amp stereo system - and you can ask him to play your favorite songs. The bar is called "Peter, Paul and Mary" - honestly not my favorite style of music. And I even coulnd't find a webpage or an address - only that little piece of information on Facebook. But after stepping down the stairs to the cellar my eyes almost poped out of my head. This is the audio system: Enourmus huge corner horn loudspeakers from Western Electric. Pretty old I'd suppose but delivering an incredible present dynamics into the room. And plenty of tube equipment from Jadis, NSA Labs and Shindo Laboratories Western Electric 300B Limited amps from Tokyo. And the owner (I was so amazed I had simply forgotten to ask for his name) collects records since 40 years. And we had many wishes that night. Actually when we did enter Peter, Paul and Mary he played an old Helloween song. That must have been destiny. A German entering a bar in Korea and the owner is playing an old song by one of Germany's best heavy metal bands ever. And it went on with the Doors, Rainbow's Stargazer, Scorpions, later Deep Purple's Perfect Strangers, a bit of Santana, Carly Simon, Jimi Hendrix, David Bowie ...Ronnie James Dio's Holy Diver, Gary Moore, Peter Gabriel's San Jacinto ... and many many more great songs ... Of course we were the last guests leaving the place at 2am in the morning - and I've never ever had a better night in a bar before ... I could have stayed days listening to so many records  ... Thanks Ryan, that was a phantastic night! -Mike

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  • Indie Software Developers - How do I handle taxes?

    - by Connor
    I apologize if this is the wrong site to post on, perhaps someone could point me to the proper place if it is not. Hello, I am 17 years old and currently develop applications/games for Android and iPhone as well as develop internet websites and code a variety of my own projects. I have been very fortunate and have made a large amount of money and continue to make money online to the point where I do not need a stable job, though I'd like to get one after college. I've never held a job anywhere, and have never had to pay taxes. I'm coming into a lot of issues and I am quite confused. I get money from MANY sources- 15 different advertisement networks(!), 4 different payment processors, 5 different affiliate networks and a variety of other sources. All of them pay to different places and at different times (checking account, PayPal, reloadable debit card, ect.) I essentially have a list in a Notepad with names and login information for each source. I have also created a PHP script that uses cURL to grab all the revenue from each service, add it all up, then text me every few hours so I can keep track. It's a mess, but it's working OK, and I can create custom reports (for IRS?). But enough of that, my questions are about taxes in the US, and how indie developers handle it all. I'm at slightly over $250k so far this year, with negligible earnings last year. I have it all stockpiled in a bank account and haven't touched it, I'm a bit scared to. What do I file as? A sole proprietor, a business, just a regular person? How can I handle all of the different revenue sources? (AdSense, CJ, LinkShare) So far none of them have sent me any paperwork on taxes and I've read that I'm supposed to pay taxes quarterly? Do I need paperwork from EACH source to file? Or can I just say I got $x total and that'd be it? What percentage do you pay of total earnings? Average? Should I create an LLC? A corporation? Or stay as a developer? What would be the cheapest options? Could I go to jail? I haven't touched the money except a few dollars to help my parents pay the mortgage once. Any insight would be great. My parents have no idea what I should do, both have no forms of higher education and both have no high school diploma's. They just live day by day with simple jobs. I appreciate any help or experience with this.

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  • New security configuration flag in UCM PS3

    - by kyle.hatlestad
    While the recent Patch Set 3 (PS3) release was mostly focused on bug fixes and such, a new configuration flag was added for security. In 10gR3 and prior versions, UCM had a component called Collaboration Manager which allowed for project folders to be created and groups of users assigned as members to collaborate on documents. With this component came access control lists (ACL) for content and folders. Users could assign specific security rights on each and every document and folder within a project. And it was possible to enable these ACL's without having the Collaboration Manager component enabled. But it took some special instructions (see technote# 603148.1) and added some extraneous pieces still related to Collaboration Manager. When 11g came out, Collaboration Manager was no longer available. But the configuration settings to turn on ACLs were still there. Well, in PS3 they've been cleaned up a bit and a new configuration flag has been added to simply turn on the ACL fields and none of the other collaboration bits. To enable ACLs: UseEntitySecurity=true Along with this configuration flag to turn ACLs on, you also need to define which Security Groups will honor the ACL fields. If an ACL is applied to a content item with a Security Group outside this list, it will be ignored. SpecialAuthGroups=HumanResources,Legal,Marketing Save the settings and restart the instance. Upon restart, two new metadata fields will be created: xClbraUserList, xClbraAliasList. If you are using OracleTextSearch as the search indexer, be sure to run a Fast Rebuild on the collection. On the Check In, Search, and Update pages, values are added by simply typing in the value and getting a type-ahead list of possible values. Select the value, click Add and then set the level of access (Read, Write, Delete, or Admin). If all of the fields are blank, then it simply falls back to just Security Group and Account access. As for how they are stored in the metadata fields, each entry starts with it's identifier: ampersand (&) symbol for users, "at" (@) symbol for groups, and colon (:) for roles. Following that is the entity name. And at the end is the level of access in paranthesis. e.g. (RWDA). And each entry is separated by a comma. So if you were populating values through batch loader or an external source, the values would be defined this way. Detailed information on Access Control Lists can be found in the Oracle Fusion Middleware System Administrator's Guide for Oracle Content Server.

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  • Will my self-taught code be fine, or should I take it to the professional level?

    - by G1i1ch
    Lately I've been getting professional work, hanging out with other programmers, and making friends in the industry. The only thing is I'm 100% self-taught. It's caused my style to extremely deviate from the style of those that are properly trained. It's the techniques and organization of my code that's different. It's a mixture of several things I do. I tend to blend several programming paradigms together. Like Functional and OO. I lean to the Functional side more than OO, but I see the use of OO when something would make more sense as an abstract entity. Like a game object. Next I also go the simple route when doing something. When in contrast, it seems like sometimes the code I see from professional programmers is complicated for the sake of it! I use lots of closures. And lastly, I'm not the best commenter. I find it easier just to read through my code than reading the comment. And most cases I just end up reading the code even if there are comments. Plus I've been told that, because of how simply I write my code, it's very easy to read it. I hear professionally trained programmers go on and on about things like unit tests. Something I've never used before so I haven't even the faintest idea of what they are or how they work. Lots and lots of underscores "_", which aren't really my taste. Most of the techniques I use are straight from me, or a few books I've read. Don't know anything about MVC, I've heard a lot about it though with things like backbone.js. I think it's a way to organize an application. It just confuses me though because by now I've made my own organizational structures. It's a bit of a pain. I can't use template applications at all when learning something new like with Ubuntu's Quickly. I have trouble understanding code that I can tell is from someone trained. Complete OO programming really leaves a bad taste in my mouth, yet that seems to be what EVERYONE else is strictly using. It's left me not that confident in the look of my code, or wondering whether I'll cause sparks when joining a company or maybe contributing to open source projects. In fact I'm rather scared of the fact that people will eventually be checking out my code. Is this just something normal any programmer goes through or should I really look to change up my techniques?

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  • Oracle Solaris at the OpenStack Summit in Atlanta

    - by Glynn Foster
    I had the fortune of attending my 2nd OpenStack summit in Atlanta a few weeks ago and it turned out to be a really excellent event. Oracle had many folks there this time around across a variety of different engineering teams - Oracle Solaris, Oracle ZFSSA, Oracle Linux, Oracle VM and more. Really great to see continuing momentum behind the project and we're very happy to be involved. Here's a list of the highlights that I had during the summit: The operators track was a really excellent addition, with a chance for users/administrators to voice their opinions based on experiences. Really good to hear how OpenStack is making businesses more agile, but also equally good to hear about some of the continuing frustrations they have (fortunately many of them are new and being addressed). Seeing this discussion morph into a "Win the enterprise" working group is also very pleasing. Enjoyed Troy Toman's keynote (Rackspace) about designing a planet scale cloud OS and the interoperability challenges ahead of us. I've been following some of the discussion around DefCore for a bit and while I have some concerns, I think it's mostly heading in the right direction. Certainly seems like there's a balance to strike to ensure that this effects the OpenStack vendors in such a way as to avoid negatively impacting our end users. Also enjoyed Toby Ford's keynote (AT&T) about his desire for a NVF (Network Function Virtualization) architecture. What really resonated was also his desire for OpenStack to start addressing the typical enterprise workload, being less like cattle and more like pets. The design summit was, as per usual, pretty intense for - definitely would get more value from these if I knew the code base a little better. Nevertheless, attended some really great sessions and got a better feeling of the roadmap for Juno. Markus Flierl gave a great presentation (see below) at the demo theatre for what we're doing with OpenStack on Oracle Solaris (and more widely at Oracle across different products). Based on the discussions that we had at the Oracle booth, there's a huge amount of interest there and we talked to some great customers during the week about their thoughts and directions in this respect. Undoubtedly Atlanta had some really good food. Highlights were the smoked ribs and brisket and the SweetWater brewing company. That said, I also loved the fried chicken, fried green tomatoes and collared greens, and wonderful hosting of "big momma" at Pitty Pat's Porch. Couldn't quite bring myself to eat biscuits and gravy in the morning though. Visiting the World of Coca-Cola just before flying out. A total brain washing exercise, but very enjoyable. And very much liked Beverly (contrary to many other opinions on the internet) - but then again, I'd happily drink tonic water every day of the year... Looking forward to Paris in November!

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  • Travelling MVP #3: Community event in Varna, Bulgaria

    - by DigiMortal
    Second stop in my DevReach 2012 trip was at Varna. We had not much time to hang around there but this problem will get fixed next year if not before. But still we had sessions there with Dimitar Georgijev and I had also chance to meet local techies. Next time we will have more tech and beers for sure! We started in the morning from Bucharest and travelled through Ruse, Razgrad and Shumen to Varna. It’s about 275km. We used cab, local bus and Dimitar father’s car. We had one food stop in Ruse and after that we went directly to Varna. Here is our route on map. Varna is Bulgarian city that locates on western coast of Black Sea. I have been there once before this trip and it’s good place to have vacation under sun. Also autumn is there milder than here in Estonia (third day of snow is going on). Bulgaria has some good beers, my favorite mankind killer called rakia and very good national cuisine. Food is made of fresh stuff and it is damn good experience. Here are some arbitrarily selected images (you can click on these to view at original size): Old bus “monument” in Razgrad Stuffed peppers, Bulgarian national cuisine Infra-red community having good time and beers We made our sessions at one study class of Varna technical university. It’s a little bit old style university but everything we needed was there and we had no problems with machinery. Sessions were same as in Bucharest. The user group in Varna is brand new and hopefully it will be something bigger one good day. At least I try to make my commits so they get on their feet quicker. As we had not much time to announce the event there was about 15 guys listening to us and I’m happy that it was not too much hyped event because still I was getting my first experiences with foreign audiences. After sessions we took our stuff to hotel and went to hang around with local techies. We had some good time there and made some new friends. Next time when I go to Varna I go back as more experienced speaker and I plan to do there one tougher and highly challenging session. Maybe somebody from Estonian community will join me and then it will be well planned surprise-attack to Varna :)

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  • Mathemagics - 3 consecutive number

    - by PointsToShare
    © 2011 By: Dov Trietsch. All rights reserved Three Consecutive numbers When I was young and handsome (OK, OK, just young), my father used to challenge us with riddles and tricks involving Logic, Math and general knowledge. Most of the time, at least after reaching the ripe age of 10, I would see thru his tricks in no time. This one is a bit more subtle. I had to think about it for close to an hour and then when I had the ‘AHA!’ effect, I could not understand why it had taken me so long. So here it is. You select a volunteer from the audience (or a shill, but that would be cheating!) and ask him to select three consecutive numbers, all of them 1 or 2 digits. So {1, 2, 3} would be good, albeit trivial set, as would {8, 9, 10} or {97, 98, 99} but not {99, 99, 100} (why?!). Now, using a calculator – and these days almost every phone has a built in calculator – he is to perform these steps: 1.      Select a single digit 2.      Multiply it by 3 and write it down 3.      Add the 3 consecutive numbers 4.      Add the number from step 2 5.      Multiply the sum by 67 6.      Now tell me the last 2 digits of the result and also the number you wrote down in step 2 I will tell you which numbers you selected. How do I do this? I’ll give you the mechanical answer, but because I like you to have the pleasure of an ‘AHA!’ effect, I will not really explain the ‘why’. So let’s you selected 30, 31, and 32 and also that your 3 multiple was 24, so here is what you get 30 + 31 + 32 = 93 93 + 24 = 117 117 x 67 = 7839, last 2 digits are 39, so you say “the last 2 digits are 39, and the other number is 24.” Now, I divide 24 by 3 getting 8. I subtract 8 from 39 and get 31. I then subtract 1 from this getting 30, and say: “You selected 30, 31, and 32.” This is the ‘how’. I leave the ‘why’ to you! That’s all folks! PS do you really want to know why? Post a feedback below. When 11 people or more will have asked for it, I’ll add a link to the full explanation.

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  • Fixing the #mvvmlight code snippets in Visual Studio 11

    - by Laurent Bugnion
    If you installed the latest MVVM Light version for Windows 8, you may encounter an issue where code snippets are not displayed correctly in the Intellisense popup. I am working on a fix, but for now here is how you can solve the issue manually. The code snippets MVVM Light, when installed correctly, will install a set of code snippets that are very useful to allow you to type less code. As I use to say, code is where bugs are, so you want to type as little of that as possible ;) With code snippets, you can easily auto-insert segments of code and easily replace the keywords where needed. For instance, every coder who uses MVVM as his favorite UI pattern for XAML based development is used to the INotifyPropertyChanged implementation, and how boring it can be to type these “observable properties”. Obviously a good fix would be something like an “Observable” attribute, but that is not supported in the language or the framework for the moment. Another fix involves “IL weaving”, which is a post-build operation modifying the generate IL code and inserting the “RaisePropertyChanged” instruction. I admire the invention of those who developed that, but it feels a bit too much like magic to me. I prefer more “down to earth” solutions, and thus I use the code snippets. Fixing the issue Normally, you should see the code snippets in Intellisense when you position your cursor in a C# file and type mvvm. All MVVM Light snippets start with these 4 letters. Normal MVVM Light code snippets However, in Windows 8 CP, there is an issue that prevents them to appear correctly, so you won’t see them in the Intellisense windows. To restore that, follow the steps: In Visual Studio 11, open the menu Tools, Code Snippets Manager. In the combobox, select Visual C#. Press Add… Navigate to C:\Program Files (x86)\Laurent Bugnion (GalaSoft)\Mvvm Light Toolkit\SnippetsWin8 and select the CSharp folder. Press Select Folder. Press OK to close the Code Snippets Manager. Now if you type mvvm in a C# file, you should see the snippets in your Intellisense window. Cheers Laurent   Laurent Bugnion (GalaSoft) Subscribe | Twitter | Facebook | Flickr | LinkedIn

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  • The Red Gate Guide to SQL Server Team based Development Free e-book

    - by Mladen Prajdic
    After about 6 months of work, the new book I've coauthored with Grant Fritchey (Blog|Twitter), Phil Factor (Blog|Twitter) and Alex Kuznetsov (Blog|Twitter) is out. They're all smart folks I talk to online and this book is packed with good ideas backed by years of experience. The book contains a good deal of information about things you need to think of when doing any kind of multi person database development. Although it's meant for SQL Server, the principles can be applied to any database platform out there. In the book you will find information on: writing readable code, documenting code, source control and change management, deploying code between environments, unit testing, reusing code, searching and refactoring your code base. I've written chapter 5 about Database testing and chapter 11 about SQL Refactoring. In the database testing chapter (chapter 5) I cover why you should test your database, why it is a good idea to have a database access interface composed of stored procedures, views and user defined functions, what and how to test. I talk about how there are many testing methods like black and white box testing, unit and integration testing, error and stress testing and why and how you should do all those. Sometimes you have to convince management to go for testing in the development lifecycle so I give some pointers and tips how to do that. Testing databases is a bit different from testing object oriented code in a way that to have independent unit tests you need to rollback your code after each test. The chapter shows you ways to do this and also how to avoid it. At the end I show how to test various database objects and how to test access to them. In the SQL Refactoring chapter (chapter 11) I cover why refactor and where to even begin refactoring. I also who you a way to achieve a set based mindset to solve SQL problems which is crucial to good SQL set based programming and a few commonly seen problems to refactor. These problems include: using functions on columns in the where clause, SELECT * problems, long stored procedure with many input parameters, one subquery per condition in the select statement, cursors are good for anything problem, using too large data types everywhere and using your data in code for business logic anti-pattern. You can read more about it and download it here: The Red Gate Guide to SQL Server Team-based Development Hope you like it and send me feedback if you wish too.

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  • Best pathfinding for a 2D world made by CPU Perlin Noise, with random start- and destinationpoints?

    - by Mathias Lykkegaard Lorenzen
    I have a world made by Perlin Noise. It's created on the CPU for consistency between several devices (yes, I know it takes time - I have my techniques that make it fast enough). Now, in my game you play as a fighter-ship-thingy-blob or whatever it's going to be. What matters is that this "thing" that you play as, is placed in the middle of the screen, and moves along with the camera. The white stuff in my world are walls. The black stuff is freely movable. Now, as the player moves around he will constantly see "monsters" spawning around him in a circle (a circle that's larger than the screen though). These monsters move inwards and try to collide with the player. This is the part that's tricky. I want these monsters to constantly spawn, moving towards the player, but avoid walls entirely. I've added a screenshot below that kind of makes it easier to understand (excuse me for my bad drawing - I was using Paint for this). In the image above, the following rules apply. The red dot in the middle is the player itself. The light-green rectangle is the boundaries of the screen (in other words, what the player sees). These boundaries move with the player. The blue circle is the spawning circle. At the circumference of this circle, monsters will spawn constantly. This spawncircle moves with the player and the boundaries of the screen. Each monster spawned (shown as yellow triangles) wants to collide with the player. The pink lines shows the path that I want the monsters to move along (or something similar). What matters is that they reach the player without colliding with the walls. The map itself (the one that is Perlin Noise generated on the CPU) is saved in memory as two-dimensional bit-arrays. A 1 means a wall, and a 0 means an open walkable space. The current tile size is pretty small. I could easily make it a lot larger for increased performance. I've done some path algorithms before such as A*. I don't think that's entirely optimal here though.

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  • Good approach for hundreds of comsumers and big files

    - by ????? ???????
    I have several files (nearly 1GB each) with data. Data is a string line. I need to process each of these files with several hundreds of consumers. Each of these consumers does some processing that differs from others. Consumers do not write anywhere concurrently. They only need input string. After processing they update their local buffers. Consumers can easily be executed in parallel. Important: With one specific file each consumer has to process all lines (without skipping) in correct order (as they appear in file). The order of processing different files doesn't matter. Processing of a single line by one consumer is comparably fast. I expect less than 50 microseconds on Corei5. So now I'm looking for the good approach to this problem. This is going to be be a part of a .NET project, so please let's stick with .NET only (C# is preferable). I know about TPL and DataFlow. I guess that the most relevant would be BroadcastBlock. But i think that the problem here is that with each line I'll have to wait for all consumers to finish in order to post the new one. I guess that it would be not very efficient. I think that ideally situation would be something like this: One thread reads from file and writes to the buffer. Each consumer, when it is ready, reads the line from the buffer concurrently and processes it. The entry from the buffer shouldn't be deleted as one consumer reads it. It can be deleted only when all consumers have processed it. TPL schedules consumer threads itself. If one consumer outperforms the others, it shouldn't wait and can read more recent entries from the buffer. Am i right with this kind of approach? Whether yes or not, how can i implement the good solution? A bit was already discussed on StackOverflow: link

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  • SQL SERVER – A Puzzle Part 3 – Fun with SEQUENCE in SQL Server 2012 – Guess the Next Value

    - by pinaldave
    Before continuing this blog post – please read the two part of the SEQUENCE Puzzle here A Puzzle – Fun with SEQUENCE in SQL Server 2012 – Guess the Next Value and A Puzzle Part 2 – Fun with SEQUENCE in SQL Server 2012 – Guess the Next Value Where we played a simple guessing game about predicting next value. The answers the of puzzle is shared on the blog posts as a comment. Now here is the next puzzle based on yesterday’s puzzle. I recently shared the puzzle of the blog post on local user group and it was appreciated by attendees. First execute the script which I have written here. Today’s script is bit different than yesterday’s script as well it will require you to do some service related activities. I suggest you try this on your personal computer’s test environment when no one is working on it. Do not attempt this on production server as it will for sure get you in trouble. The purpose to learn how sequence behave during the unexpected shutdowns and services restarts. Now guess what will be the next value as requested in the query. USE AdventureWorks2012 GO -- Create sequence CREATE SEQUENCE dbo.SequenceID AS BIGINT START WITH 1 INCREMENT BY 1 MINVALUE 1 MAXVALUE 500 CYCLE CACHE 100; GO -- Following will return 1 SELECT next value FOR dbo.SequenceID; ------------------------------------- -- simulate server crash by restarting service -- do not attempt this on production or any server in use ------------------------------------ -- Following will return ??? SELECT next value FOR dbo.SequenceID; -- Clean up DROP SEQUENCE dbo.SequenceID; GO Once the server is restarted what will be the next value for SequenceID. We can learn interesting trivia’s about this new feature of SQL Server using this puzzle. Hint: Pay special attention to the difference between new number and earlier number. Can you see the same number in the definition of the CREATE SEQUENCE? Bonus Question: How to avoid the behavior demonstrated in above mentioned query. Does it have any effect of performance? I suggest you try to attempt to answer this question without running this code in SQL Server 2012. You can restart SQL Server using command prompt as well. I will follow up of the answer in comments below. Recently my friend Vinod Kumar wrote excellent blog post on SQL Server 2012: Using SEQUENCE, you can head over there for learning sequence in details. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Achieving Zero Downtime Deployment

    - by MattW
    I am trying to achieve zero downtime deployments so I can deploy less during off hours and more during "slower" hours - or anytime, in theory. My current setup, somewhat simplified: Web Server A (.NET App) Web Server B (.NET App) Database Server (SQL Server) My current deployment process: "Stop" the sites on both Web Server A and B Upgrade the database schema for the version of the app being deployed Update Web Server A Update Web Server B Bring everything back online Current Problem This leads to a small amount of downtime each month - about 30 mins. I do this during off hours, so it isn't a huge problem - but it is something I'd like to get away from. Also - there is no way to really go 'back'. I don't generally make rollback DB scripts - only upgrade scripts. Leveraging The Load Balancer I'd love to be able to upgrade one Web Server at a time. Take Web Server A out of the load balancer, upgrade it, put it back online, then repeat for Web Server B. The problem is the database. Each version of my software will need to execute against a different version of the database - so I am sort of "stuck". Possible Solution A current solution I am considering is adopting the following rules: Never delete a database table. Never delete a database column. Never rename a database column. Never reorder a column. Every stored procedure must be versioned. Meaning - 'spFindAllThings' will become 'spFindAllThings_2' when it is edited. Then it becomes 'spFindAllThings_3' when edited again. Same rule applies to views. While, this seems a bit extreme - I think it solves the problem. Each version of the application will be hitting the DB in a non breaking way. The code expects certain results from the views/stored procedures - and this keeps that 'contract' valid. The problem is - it just seeps sloppy. I know I can clean up old stored procedures after the app is deployed for awhile, but it just feels dirty. Also - it depends on all of the developers following these rule, which will mostly happen, but I imagine someone will make a mistake. Finally - My Question Is this sloppy or hacky? Is anybody else doing it this way? How are other people solving this problem?

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  • OpenGL - have object follow mouse

    - by kevin james
    I want to have an object follow around my mouse on the screen in OpenGL. (I am also using GLEW, GLFW, and GLM). The best idea I've come up with is: Get the coordinates within the window with glfwGetCursorPos. The window was created with window = glfwCreateWindow( 1024, 768, "Test", NULL, NULL); and the code to get coordinates is double xpos, ypos; glfwGetCursorPos(window, &xpos, &ypos); Next, I use GLM unproject, to get the coordinates in "object space" glm::vec4 viewport = glm::vec4(0.0f, 0.0f, 1024.0f, 768.0f); glm::vec3 pos = glm::vec3(xpos, ypos, 0.0f); glm::vec3 un = glm::unProject(pos, View*Model, Projection, viewport); There are two potential problems I can already see. The viewport is fine, as the initial x,y, coordinates of the lower left are indeed 0,0, and it's indeed a 1024*768 window. However, the position vector I create doesn't seem right. The Z coordinate should probably not be zero. However, glfwGetCursorPos returns 2D coordinates, and I don't know how to go from there to the 3D window coordinates, especially since I am not sure what the 3rd dimension of the window coordinates even means (since computer screens are 2D). Then, I am not sure if I am using unproject correctly. Assume the View, Model, Projection matrices are all OK. If I passed in the correct position vector in Window coordinates, does the unproject call give me the coordinates in Object coordinates? I think it does, but the documentation is not clear. Finally, to each vertex of the object I want to follow the mouse around, I just increment the x coordinate by un[0], the y coordinate by -un[1], and the z coordinate by un[2]. However, since my position vector that is being unprojected is likely wrong, this is not giving good results; the object does move as my mouse moves, but it is offset quite a bit (i.e. moving the mouse a lot doesn't move the object that much, and the z coordinate is very large). I actually found that the z coordinate un[2] is always the same value no matter where my mouse is, probably because the position vector I pass into unproject always has a value of 0.0 for z. Edit: The (incorrectly) unprojected x-values range from about -0.552 to 0.552, and the y-values from about -0.411 to 0.411.

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  • Set a Video as Your Desktop Wallpaper with VLC

    - by DigitalGeekery
    Are you tired of static desktop wallpapers and want something a bit more entertaining? Today we’ll take a look at setting a video as wallpaper in VLC media player. Download and install VLC player. You’ll find the download link below. Open VLC and select Tools > Preferences. On the Preferences windows, select the Video button on the left. Under Video Settings, select DirectX video output from the Output dropdown list. Click Save before exiting and then restart VLC. Next, select a video and begin playing it with VLC. Right-click on the screen, select Video, then DirectX Wallpaper.   You can achieve the same result by selecting Video from the Menu and clicking DirectX Wallpaper.   If you’re using Windows Aero Themes, you may get the warning message below and your theme will switch automatically to a basic theme.   After the Wallpaper is enabled, minimize VLC player and enjoy the show as you work.     When you are ready to switch back to your normal wallpaper, click Video, and then close out of VLC.   Occasionally we had to manually change our wallpaper back to normal. You can do that by right clicking on the desktop and selecting your theme.   Conclusion This might not make the most productive desktop environment, but it is pretty cool. It’s definitely not the same old boring wallpaper! Download VLC Similar Articles Productive Geek Tips Dual Monitors: Use a Different Wallpaper on Each Desktop in Windows 7, Vista or XPDual Monitors: Use a Different Wallpaper on Each DesktopDesktop Fun: Video Game Icon PacksDesktop Fun: Starship Theme WallpapersDesktop Fun: Mountains Theme Wallpapers TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips All My Movies 5.9 CloudBerry Online Backup 1.5 for Windows Home Server Snagit 10 VMware Workstation 7 OpenDNS Guide Google TV The iPod Revolution Ultimate Boot CD can help when disaster strikes Windows Firewall with Advanced Security – How To Guides Sculptris 1.0, 3D Drawing app

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  • Space partitioning when everything is moving

    - by Roy T.
    Background Together with a friend I'm working on a 2D game that is set in space. To make it as immersive and interactive as possible we want there to be thousands of objects freely floating around, some clustered together, others adrift in empty space. Challenge To unburden the rendering and physics engine we need to implement some sort of spatial partitioning. There are two challenges we have to overcome. The first challenge is that everything is moving so reconstructing/updating the data structure has to be extremely cheap since it will have to be done every frame. The second challenge is the distribution of objects, as said before there might be clusters of objects together and vast bits of empty space and to make it even worse there is no boundary to space. Existing technologies I've looked at existing techniques like BSP-Trees, QuadTrees, kd-Trees and even R-Trees but as far as I can tell these data structures aren't a perfect fit since updating a lot of objects that have moved to other cells is relatively expensive. What I've tried I made the decision that I need a data structure that is more geared toward rapid insertion/update than on giving back the least amount of possible hits given a query. For that purpose I made the cells implicit so each object, given it's position, can calculate in which cell(s) it should be. Then I use a HashMap that maps cell-coordinates to an ArrayList (the contents of the cell). This works fairly well since there is no memory lost on 'empty' cells and its easy to calculate which cells to inspect. However creating all those ArrayLists (worst case N) is expensive and so is growing the HashMap a lot of times (although that is slightly mitigated by giving it a large initial capacity). Problem OK so this works but still isn't very fast. Now I can try to micro-optimize the JAVA code. However I'm not expecting too much of that since the profiler tells me that most time is spent in creating all those objects that I use to store the cells. I'm hoping that there are some other tricks/algorithms out there that make this a lot faster so here is what my ideal data structure looks like: The number one priority is fast updating/reconstructing of the entire data structure Its less important to finely divide the objects into equally sized bins, we can draw a few extra objects and do a few extra collision checks if that means that updating is a little bit faster Memory is not really important (PC game)

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  • Microsoft Introduces WebMatrix

    - by Rick Strahl
    originally published in CoDe Magazine Editorial Microsoft recently released the first CTP of a new development environment called WebMatrix, which along with some of its supporting technologies are squarely aimed at making the Microsoft Web Platform more approachable for first-time developers and hobbyists. But in the process, it also provides some updated technologies that can make life easier for existing .NET developers. Let’s face it: ASP.NET development isn’t exactly trivial unless you already have a fair bit of familiarity with sophisticated development practices. Stick a non-developer in front of Visual Studio .NET or even the Visual Web Developer Express edition and it’s not likely that the person in front of the screen will be very productive or feel inspired. Yet other technologies like PHP and even classic ASP did provide the ability for non-developers and hobbyists to become reasonably proficient in creating basic web content quickly and efficiently. WebMatrix appears to be Microsoft’s attempt to bring back some of that simplicity with a number of technologies and tools. The key is to provide a friendly and fully self-contained development environment that provides all the tools needed to build an application in one place, as well as tools that allow publishing of content and databases easily to the web server. WebMatrix is made up of several components and technologies: IIS Developer Express IIS Developer Express is a new, self-contained development web server that is fully compatible with IIS 7.5 and based on the same codebase that IIS 7.5 uses. This new development server replaces the much less compatible Cassini web server that’s been used in Visual Studio and the Express editions. IIS Express addresses a few shortcomings of the Cassini server such as the inability to serve custom ISAPI extensions (i.e., things like PHP or ASP classic for example), as well as not supporting advanced authentication. IIS Developer Express provides most of the IIS 7.5 feature set providing much better compatibility between development and live deployment scenarios. SQL Server Compact 4.0 Database access is a key component for most web-driven applications, but on the Microsoft stack this has mostly meant you have to use SQL Server or SQL Server Express. SQL Server Compact is not new-it’s been around for a few years, but it’s been severely hobbled in the past by terrible tool support and the inability to support more than a single connection in Microsoft’s attempt to avoid losing SQL Server licensing. The new release of SQL Server Compact 4.0 supports multiple connections and you can run it in ASP.NET web applications simply by installing an assembly into the bin folder of the web application. In effect, you don’t have to install a special system configuration to run SQL Compact as it is a drop-in database engine: Copy the small assembly into your BIN folder (or from the GAC if installed fully), create a connection string against a local file-based database file, and then start firing SQL requests. Additionally WebMatrix includes nice tools to edit the database tables and files, along with tools to easily upsize (and hopefully downsize in the future) to full SQL Server. This is a big win, pending compatibility and performance limits. In my simple testing the data engine performed well enough for small data sets. This is not only useful for web applications, but also for desktop applications for which a fully installed SQL engine like SQL Server would be overkill. Having a local data store in those applications that can potentially be accessed by multiple users is a welcome feature. ASP.NET Razor View Engine What? Yet another native ASP.NET view engine? We already have Web Forms and various different flavors of using that view engine with Web Forms and MVC. Do we really need another? Microsoft thinks so, and Razor is an implementation of a lightweight, script-only view engine. Unlike the Web Forms view engine, Razor works only with inline code, snippets, and markup; therefore, it is more in line with current thinking of what a view engine should represent. There’s no support for a “page model” or any of the other Web Forms features of the full-page framework, but just a lightweight scripting engine that works with plain markup plus embedded expressions and code. The markup syntax for Razor is geared for minimal typing, plus some progressive detection of where a script block/expression starts and ends. This results in a much leaner syntax than the typical ASP.NET Web Forms alligator (<% %>) tags. Razor uses the @ sign plus standard C# (or Visual Basic) block syntax to delineate code snippets and expressions. Here’s a very simple example of what Razor markup looks like along with some comment annotations: <!DOCTYPE html> <html>     <head>         <title></title>     </head>     <body>     <h1>Razor Test</h1>          <!-- simple expressions -->     @DateTime.Now     <hr />     <!-- method expressions -->     @DateTime.Now.ToString("T")          <!-- code blocks -->     @{         List<string> names = new List<string>();         names.Add("Rick");         names.Add("Markus");         names.Add("Claudio");         names.Add("Kevin");     }          <!-- structured block statements -->     <ul>     @foreach(string name in names){             <li>@name</li>     }     </ul>           <!-- Conditional code -->        @if(true) {                        <!-- Literal Text embedding in code -->        <text>         true        </text>;    }    else    {        <!-- Literal Text embedding in code -->       <text>       false       </text>;    }    </body> </html> Like the Web Forms view engine, Razor parses pages into code, and then executes that run-time compiled code. Effectively a “page” becomes a code file with markup becoming literal text written into the Response stream, code snippets becoming raw code, and expressions being written out with Response.Write(). The code generated from Razor doesn’t look much different from similar Web Forms code that only uses script tags; so although the syntax may look different, the operational model is fairly similar to the Web Forms engine minus the overhead of the large Page object model. However, there are differences: -Razor pages are based on a new base class, Microsoft.WebPages.WebPage, which is hosted in the Microsoft.WebPages assembly that houses all the Razor engine parsing and processing logic. Browsing through the assembly (in the generated ASP.NET Temporary Files folder or GAC) will give you a good idea of the functionality that Razor provides. If you look closely, a lot of the feature set matches ASP.NET MVC’s view implementation as well as many of the helper classes found in MVC. It’s not hard to guess the motivation for this sort of view engine: For beginning developers the simple markup syntax is easier to work with, although you obviously still need to have some understanding of the .NET Framework in order to create dynamic content. The syntax is easier to read and grok and much shorter to type than ASP.NET alligator tags (<% %>) and also easier to understand aesthetically what’s happening in the markup code. Razor also is a better fit for Microsoft’s vision of ASP.NET MVC: It’s a new view engine without the baggage of Web Forms attached to it. The engine is more lightweight since it doesn’t carry all the features and object model of Web Forms with it and it can be instantiated directly outside of the HTTP environment, which has been rather tricky to do for the Web Forms view engine. Having a standalone script parser is a huge win for other applications as well – it makes it much easier to create script or meta driven output generators for many types of applications from code/screen generators, to simple form letters to data merging applications with user customizability. For me personally this is very useful side effect and who knows maybe Microsoft will actually standardize they’re scripting engines (die T4 die!) on this engine. Razor also better fits the “view-based” approach where the view is supposed to be mostly a visual representation that doesn’t hold much, if any, code. While you can still use code, the code you do write has to be self-contained. Overall I wouldn’t be surprised if Razor will become the new standard view engine for MVC in the future – and in fact there have been announcements recently that Razor will become the default script engine in ASP.NET MVC 3.0. Razor can also be used in existing Web Forms and MVC applications, although that’s not working currently unless you manually configure the script mappings and add the appropriate assemblies. It’s possible to do it, but it’s probably better to wait until Microsoft releases official support for Razor scripts in Visual Studio. Once that happens, you can simply drop .cshtml and .vbhtml pages into an existing ASP.NET project and they will work side by side with classic ASP.NET pages. WebMatrix Development Environment To tie all of these three technologies together, Microsoft is shipping WebMatrix with an integrated development environment. An integrated gallery manager makes it easy to download and load existing projects, and then extend them with custom functionality. It seems to be a prominent goal to provide community-oriented content that can act as a starting point, be it via a custom templates or a complete standard application. The IDE includes a project manager that works with a single project and provides an integrated IDE/editor for editing the .cshtml and .vbhtml pages. A run button allows you to quickly run pages in the project manager in a variety of browsers. There’s no debugging support for code at this time. Note that Razor pages don’t require explicit compilation, so making a change, saving, and then refreshing your page in the browser is all that’s needed to see changes while testing an application locally. It’s essentially using the auto-compiling Web Project that was introduced with .NET 2.0. All code is compiled during run time into dynamically created assemblies in the ASP.NET temp folder. WebMatrix also has PHP Editing support with syntax highlighting. You can load various PHP-based applications from the WebMatrix Web Gallery directly into the IDE. Most of the Web Gallery applications are ready to install and run without further configuration, with Wizards taking you through installation of tools, dependencies, and configuration of the database as needed. WebMatrix leverages the Web Platform installer to pull the pieces down from websites in a tight integration of tools that worked nicely for the four or five applications I tried this out on. Click a couple of check boxes and fill in a few simple configuration options and you end up with a running application that’s ready to be customized. Nice! You can easily deploy completed applications via WebDeploy (to an IIS server) or FTP directly from within the development environment. The deploy tool also can handle automatically uploading and installing the database and all related assemblies required, making deployment a simple one-click install step. Simplified Database Access The IDE contains a database editor that can edit SQL Compact and SQL Server databases. There is also a Database helper class that facilitates database access by providing easy-to-use, high-level query execution and iteration methods: @{       var db = Database.OpenFile("FirstApp.sdf");     string sql = "select * from customers where Id > @0"; } <ul> @foreach(var row in db.Query(sql,1)){         <li>@row.FirstName @row.LastName</li> } </ul> The query function takes a SQL statement plus any number of positional (@0,@1 etc.) SQL parameters by simple values. The result is returned as a collection of rows which in turn have a row object with dynamic properties for each of the columns giving easy (though untyped) access to each of the fields. Likewise Execute and ExecuteNonQuery allow execution of more complex queries using similar parameter passing schemes. Note these queries use string-based queries rather than LINQ or Entity Framework’s strongly typed LINQ queries. While this may seem like a step back, it’s also in line with the expectations of non .NET script developers who are quite used to writing and using SQL strings in code rather than using OR/M frameworks. The only question is why was something not included from the beginning in .NET and Microsoft made developers build custom implementations of these basic building blocks. The implementation looks a lot like a DataTable-style data access mechanism, but to be fair, this is a common approach in scripting languages. This type of syntax that uses simple, static, data object methods to perform simple data tasks with one line of code are common in scripting languages and are a good match for folks working in PHP/Python, etc. Seems like Microsoft has taken great advantage of .NET 4.0’s dynamic typing to provide this sort of interface for row iteration where each row has properties for each field. FWIW, all the examples demonstrate using local SQL Compact files - I was unable to get a SQL Server connection string to work with the Database class (the connection string wasn’t accepted). However, since the code in the page is still plain old .NET, you can easily use standard ADO.NET code or even LINQ or Entity Framework models that are created outside of WebMatrix in separate assemblies as required. The good the bad the obnoxious - It’s still .NET The beauty (or curse depending on how you look at it :)) of Razor and the compilation model is that, behind it all, it’s still .NET. Although the syntax may look foreign, it’s still all .NET behind the scenes. You can easily access existing tools, helpers, and utilities simply by adding them to the project as references or to the bin folder. Razor automatically recognizes any assembly reference from assemblies in the bin folder. In the default configuration, Microsoft provides a host of helper functions in a Microsoft.WebPages assembly (check it out in the ASP.NET temp folder for your application), which includes a host of HTML Helpers. If you’ve used ASP.NET MVC before, a lot of the helpers should look familiar. Documentation at the moment is sketchy-there’s a very rough API reference you can check out here: http://www.asp.net/webmatrix/tutorials/asp-net-web-pages-api-reference Who needs WebMatrix? Uhm… good Question Clearly Microsoft is trying hard to create an environment with WebMatrix that is easy to use for newbie developers. The goal seems to be simplicity in providing a minimal development environment and an easy-to-use script engine/language that makes it easy to get started with. There’s also some focus on community features that can be used as starting points, such as Web Gallery applications and templates. The community features in particular are very nice and something that would be nice to eventually see in Visual Studio as well. The question is whether this is too little too late. Developers who have been clamoring for a simpler development environment on the .NET stack have mostly left for other simpler platforms like PHP or Python which are catering to the down and dirty developer. Microsoft will be hard pressed to win those folks-and other hardcore PHP developers-back. Regardless of how much you dress up a script engine fronted by the .NET Framework, it’s still the .NET Framework and all the complexity that drives it. While .NET is a fine solution in its breadth and features once you get a basic handle on the core features, the bar of entry to being productive with the .NET Framework is still pretty high. The MVC style helpers Microsoft provides are a good step in the right direction, but I suspect it’s not enough to shield new developers from having to delve much deeper into the Framework to get even basic applications built. Razor and its helpers is trying to make .NET more accessible but the reality is that in order to do useful stuff that goes beyond the handful of simple helpers you still are going to have to write some C# or VB or other .NET code. If the target is a hobby/amateur/non-programmer the learning curve isn’t made any easier by WebMatrix it’s just been shifted a tad bit further along in your development endeavor when you run out of canned components that are supplied either by Microsoft or the community. The database helpers are interesting and actually I’ve heard a lot of discussion from various developers who’ve been resisting .NET for a really long time perking up at the prospect of easier data access in .NET than the ridiculous amount of code it takes to do even simple data access with raw ADO.NET. It seems sad that such a simple concept and implementation should trigger this sort of response (especially since it’s practically trivial to create helpers like these or pick them up from countless libraries available), but there it is. It also shows that there are plenty of developers out there who are more interested in ‘getting stuff done’ easily than necessarily following the latest and greatest practices which are overkill for many development scenarios. Sometimes it seems that all of .NET is focused on the big life changing issues of development, rather than the bread and butter scenarios that many developers are interested in to get their work accomplished. And that in the end may be WebMatrix’s main raison d'être: To bring some focus back at Microsoft that simpler and more high level solutions are actually needed to appeal to the non-high end developers as well as providing the necessary tools for the high end developers who want to follow the latest and greatest trends. The current version of WebMatrix hits many sweet spots, but it also feels like it has a long way to go before it really can be a tool that a beginning developer or an accomplished developer can feel comfortable with. Although there are some really good ideas in the environment (like the gallery for downloading apps and components) which would be a great addition for Visual Studio as well, the rest of the development environment just feels like crippleware with required functionality missing especially debugging and Intellisense, but also general editor support. It’s not clear whether these are because the product is still in an early alpha release or whether it’s simply designed that way to be a really limited development environment. While simple can be good, nobody wants to feel left out when it comes to necessary tool support and WebMatrix just has that left out feeling to it. If anything WebMatrix’s technology pieces (which are really independent of the WebMatrix product) are what are interesting to developers in general. The compact IIS implementation is a nice improvement for development scenarios and SQL Compact 4.0 seems to address a lot of concerns that people have had and have complained about for some time with previous SQL Compact implementations. By far the most interesting and useful technology though seems to be the Razor view engine for its light weight implementation and it’s decoupling from the ASP.NET/HTTP pipeline to provide a standalone scripting/view engine that is pluggable. The first winner of this is going to be ASP.NET MVC which can now have a cleaner view model that isn’t inconsistent due to the baggage of non-implemented WebForms features that don’t work in MVC. But I expect that Razor will end up in many other applications as a scripting and code generation engine eventually. Visual Studio integration for Razor is currently missing, but is promised for a later release. The ASP.NET MVC team has already mentioned that Razor will eventually become the default MVC view engine, which will guarantee continued growth and development of this tool along those lines. And the Razor engine and support tools actually inherit many of the features that MVC pioneered, so there’s some synergy flowing both ways between Razor and MVC. As an existing ASP.NET developer who’s already familiar with Visual Studio and ASP.NET development, the WebMatrix IDE doesn’t give you anything that you want. The tools provided are minimal and provide nothing that you can’t get in Visual Studio today, except the minimal Razor syntax highlighting, so there’s little need to take a step back. With Visual Studio integration coming later there’s little reason to look at WebMatrix for tooling. It’s good to see that Microsoft is giving some thought about the ease of use of .NET as a platform For so many years, we’ve been piling on more and more new features without trying to take a step back and see how complicated the development/configuration/deployment process has become. Sometimes it’s good to take a step - or several steps - back and take another look and realize just how far we’ve come. WebMatrix is one of those reminders and one that likely will result in some positive changes on the platform as a whole. © Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET   IIS7  

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  • Excel Solver vs Solver Foundation

    - by JoshReuben
    I recently read a book http://www.amazon.com/Scientific-Engineering-Cookbook-Cookbooks-OReilly/dp/0596008791/ref=sr_1_1?ie=UTF8&s=books&qid=1296593374&sr=8-1 - the Excel Scientific and Engineering Cookbook.     The 2 main tools that this book leveraged were the Data Analysis Pack and Excel Solver. I had previously been aquanted with Microsoft Solver Foundation - this is a full fledged API for solving optimization problems, and went beyond being a mere Excel plugin - it exposed a C# programmatic interface for in process and a web service interface for out of process integration. were they the same? apparently not!   2 different solver frameworks for Excel: http://www.solver.com/index.html http://www.solverfoundation.com/ I contacted both vendors to get their perspectives.   Heres what the Excel Solver guys had to say:   "The Solver Foundation requires you to learn and use a very specific modeling language (OML). The Excel solver allows you to formulate your optimization problems without learning any new language simply by entering the formulas into cells on the Excel spreadsheet, something that nearly everyone is already familiar with doing.   The Excel Solver also allows you to seamlessly upgrade to products that combine Monte Carlo Simulation capabilities (our Risk Solver Premium and Risk Solver Platform products) which allow you to include uncertainty into your models when appropriate.   Our advanced Excel Solver Products also have a number of built in reporting tools for advanced analysis of the your model and it's results"           And Heres what the Microsoft Solver Foundation guys had to say:   "  With the release of Solver Foundation 3.0, Solver Foundation has the same kinds of solvers (plus a few more) than what is found in Excel Solver. I think there are two main differences:   1.      Problems are described differently. In Excel Solver the goals and constraints are specified inside the spreadsheet, in formulas. In Solver Foundation they are described either in .Net code that uses the Solver Foundation Services API, or using the OML modeling language in Excel. 2.      Solver Foundation’s primary strength is on solving large linear, mixed integer, and constraint models. That is, models that contain arbitrary nonlinear functions (such as trig functions, IF(), powers, etc) are handled a bit better by the Excel Solver at this point. "

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