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• Clustering Basics and Challenges

  - by Karoly Vegh

  For upcoming posts it seemed to be a good idea to dedicate some time for cluster basic concepts and theory. This post misses a lot of details that would explode the articlesize, should you have questions, do not hesitate to ask them in the comments.  The goal here is to get some concepts straight. I can't promise to give you an overall complete definitions of cluster, cluster agent, quorum, voting, fencing, split brain condition, so the following is more of an explanation. Here we go. -------- Cluster, HA, failover, switchover, scalability -------- An attempted definition of a Cluster: A cluster is a set (2+) server nodes dedicated to keep application services alive, communicating through the cluster software/framework with eachother, test and probe health status of servernodes/services and with quorum based decisions and with switchover/failover techniques keep the application services running on them available. That is, should a node that runs a service unexpectedly lose functionality/connection, the other ones would take over the and run the services, so that availability is guaranteed. To provide availability while strictly sticking to a consistent clusterconfiguration is the main goal of a cluster.  At this point we have to add that this defines a HA-cluster, a High-Availability cluster, where the clusternodes are planned to run the services in an active-standby, or failover fashion. An example could be a single instance database. Some applications can be run in a distributed or scalable fashion. In the latter case instances of the application run actively on separate clusternodes serving servicerequests simultaneously. An example for this version could be a webserver that forwards connection requests to many backend servers in a round-robin way. Or a database running in active-active RAC setup.  -------- Cluster arhitecture, interconnect, topologies -------- Now, what is a cluster made of? Servers, right. These servers (the clusternodes) need to communicate. This of course happens over the network, usually over dedicated network interfaces interconnecting all the clusternodes. These connection are called interconnects.How many clusternodes are in a cluster? There are different cluster topologies. The most simple one is a clustered pair topology, involving only two clusternodes:  There are several more topologies, clicking the image above will take you to the relevant documentation. Also, to answer the question Solaris Cluster allows you to run up to 16 servers in a cluster. Where shall these clusternodes be placed? A very important question. The right answer is: It depends on what you plan to achieve with the cluster. Do you plan to avoid only a server outage? Then you can place them right next to eachother in the datacenter. Do you need to avoid DataCenter outage? In that case of course you should place them at least in different fire zones. Or in two geographically distant DataCenters to avoid disasters like floods, large-scale fires or power outages. We call this a stretched- or campus cluster, the clusternodes being several kilometers away from eachother. To cover really large distances, you probably need to move to a GeoCluster, which is a different kind of animal.  What is a geocluster? A Geographic Cluster in Solaris Cluster terms is actually a metacluster between two, separate (locally-HA) clusters.  -------- Cluster resource types, agents, resources, resource groups -------- So how does the cluster manage my applications? The cluster needs to start, stop and probe your applications. If you application runs, the cluster needs to check regularly if the application state is healthy, does it respond over the network, does it have all the processes running, etc. This is called probing. If the cluster deems the application is in a faulty state, then it can try to restart it locally or decide to switch (stop on node A, start on node B) the service. Starting, stopping and probing are the three actions that a cluster agent does. There are many different kinds of agents included in Solaris Cluster, but you can build your own too. Examples are an agent that manages (mounts, moves) ZFS filesystems, or the Oracle DB HA agent that cares about the database, or an agent that moves a floating IP address between nodes. There are lots of other agents included for Apache, Tomcat, MySQL, Oracle DB, Oracle Weblogic, Zones, LDoms, NFS, DNS, etc.We also need to clarify the difference between a cluster resource and the cluster resource group.A cluster resource is something that is managed by a cluster agent. Cluster resource types are included in Solaris cluster (see above, e.g. HAStoragePlus, HA-Oracle, LogicalHost). You can group cluster resources into cluster resourcegroups, and switch these groups together from one node to another. To stick to the example above, to move an Oracle DB service from one node to another, you have to switch the group between nodes, and the agents of the cluster resources in the group will do the following:  On node A Shut down the DB Unconfigure the LogicalHost IP the DB Listener listens on unmount the filesystem   Then, on node B: mount the FS configure the IP  startup the DB -------- Voting, Quorum, Split Brain Condition, Fencing, Amnesia -------- How do the clusternodes agree upon their action? How do they decide which node runs what services? Another important question. Running a cluster is a strictly democratic thing.Every node has votes, and you need the majority of votes to have the deciding power. Now, this is usually no problem, clusternodes think very much all alike. Still, every action needs to be governed upon in a productive system, and has to be agreed upon. Agreeing is easy as long as the clusternodes all behave and talk to eachother over the interconnect. But if the interconnect is gone/down, this all gets tricky and confusing. Clusternodes think like this: "My job is to run these services. The other node does not answer my interconnect communication, it must be down. I'd better take control and run the services!". The problem is, as I have already mentioned, clusternodes very much think alike. If the interconnect is gone, they all assume the other node is down, and they all want to mount the data backend, enable the IP and run the database. Double IPs, double mounts, double DB instances - now that is trouble. Also, in a 2-node cluster they both have only 50% of the votes, that is, they themselves alone are not allowed to run a cluster.  This is where you need a quorum device. According to Wikipedia, the "requirement for a quorum is protection against totally unrepresentative action in the name of the body by an unduly small number of persons.". They need additional votes to run the cluster. For this requirement a 2-node cluster needs a quorum device or a quorum server. If the interconnect is gone, (this is what we call a split brain condition) both nodes start to race and try to reserve the quorum device to themselves. They do this, because the quorum device bears an additional vote, that could ensure majority (50% +1). The one that manages to lock the quorum device (e.g. if it's an FC LUN, it SCSI reserves it) wins the right to build/run a cluster, the other one - realizing he was late - panics/reboots to ensure the cluster config stays consistent.  Losing the interconnect isn't only endangering the availability of services, but it also endangers the cluster configuration consistence. Just imagine node A being down and during that the cluster configuration changes. Now node B goes down, and node A comes up. It isn't uptodate about the cluster configuration's changes so it will refuse to start a cluster, since that would lead to cluster amnesia, that is the cluster had some changes, but now runs with an older cluster configuration repository state, that is it's like it forgot about the changes.  Also, to ensure application data consistence, the clusternode that wins the race makes sure that a server that isn't part of or can't currently join the cluster can access the devices. This procedure is called fencing. This usually happens to storage LUNs via SCSI reservation.  Now, another important question: Where do I place the quorum disk?  Imagine having two sites, two separate datacenters, one in the north of the city and the other one in the south part of it. You run a stretched cluster in the clustered pair topology. Where do you place the quorum disk/server? If you put it into the north DC, and that gets hit by a meteor, you lose one clusternode, which isn't a problem, but you also lose your quorum, and the south clusternode can't keep the cluster running lacking the votes. This problem can't be solved with two sites and a campus cluster. You will need a third site to either place the quorum server to, or a third clusternode. Otherwise, lacking majority, if you lose the site that had your quorum, you lose the cluster. Okay, we covered the very basics. We haven't talked about virtualization support, CCR, ClusterFilesystems, DID devices, affinities, storage-replication, management tools, upgrade procedures - should those be interesting for you, let me know in the comments, along with any other questions. Given enough demand I'd be glad to write a followup post too. Now I really want to move on to the second part in the series: ClusterInstallation.  Oh, as for additional source of information, I recommend the documentation: http://docs.oracle.com/cd/E23623_01/index.html, and the OTN Oracle Solaris Cluster site: http://www.oracle.com/technetwork/server-storage/solaris-cluster/index.html

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• Collision detection with multiple polygons simultaneously

  - by Craig Innes

  I've written a collision system which detects/resolves collisions between a rectangular player and a convex polygon world using the Separating Axis Theorem. This scheme works fine when the player is colliding with a single polygon, but when I try to create a level made up of combinations of these shapes, the player gets "stuck" between shapes when trying to move from one polygon to the other. The reason for this seems to be that collisions are detected after the player has been pushed through the shape by its movement or gravity. When the system resolves the collision, it resolves them in an order that doesn't make sense (for example, when the player is moving from one flat rectangle to another, gravity pushes them below the ground, but the collision with the left hand side of the second block is resolved before the collision with the top of the block, meaning the player is pushed back left before being pushed back up). Other similar posts have resolved this problem by having a strict rule on which axes to resolve first. For example, always resolve the collision on the y axis, then if the object is still colliding with things, resolve on the x axis. This solution only works in the case of a completely axis oriented box world, and doesn't solve the problem if the player is stuck moving along a series of angled shapes or sliding down a wall. Does any one have any ideas of how I could alter my collision system to prevent these situations from happening?

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• jackd fails to start

  - by wickedchicken

  I'm trying to have a setup where JACK interfaces directly to ALSA and pulseaudio communicates to JACK. This setup worked OK (I had to manually start things a few times) but as I understood the Ubuntu daemon setup and perfected things jackd stopped working completely. I'm running 10.10. If I run something through ALSA I get sound no problem. However, when I run jack with realtime: /usr/bin/jackd -v -R -ch -Z -t2000 -d alsa -P I get the following error: jackd watchdog: timeout - killing jackd Conversely, if I run without realtime: /usr/bin/jackd -v -r -ch -Z -t2000 -d alsa -P I get: ALSA: poll time out, polled for 32032138 usecs DRIVER NT: could not run driver cycle Jack was working just fine before I made these changes; while I don't have an exact copy of my original configuration I recall running the bare minimum of options worked fine. I've seen some articles saying the problem is with ALSA capture. In fact, I tried enabling capture in alsamixer once and everything worked! On reboot that success was not repeated and I haven't been able to get jack working since. That shouldn't matter because specifying -P should obviate any capture issues. Short summary: I can't get jackd to work under any circumstances (unless I specify -d dummy). Sound works with other programs with ALSA, but when I run JACK the daemon opens the card but times out and dies. JACK worked fine before but I can't figure out what changed (or where to even look). I should mention I am running with CPU speed throttling on, but I'm using HPET to mitigate this (and I've run jack with no issue before). Thanks!

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• Project Euler 51: Ruby

  - by Ben Griswold

  In my attempt to learn Ruby out in the open, here’s my solution for Project Euler Problem 51.  I know I started back up with Python this week, but I have three more Ruby solutions in the hopper and I wanted to share. For the record, Project Euler 51 was the second hardest Euler problem for me thus far. Yeah. As always, any feedback is welcome. # Euler 51 # http://projecteuler.net/index.php?section=problems&id=51 # By replacing the 1st digit of *3, it turns out that six # of the nine possible values: 13, 23, 43, 53, 73, and 83, # are all prime. # # By replacing the 3rd and 4th digits of 56**3 with the # same digit, this 5-digit number is the first example # having seven primes among the ten generated numbers, # yielding the family: 56003, 56113, 56333, 56443, # 56663, 56773, and 56993. Consequently 56003, being the # first member of this family, is the smallest prime with # this property. # # Find the smallest prime which, by replacing part of the # number (not necessarily adjacent digits) with the same # digit, is part of an eight prime value family. timer_start = Time.now require 'mathn' def eight_prime_family(prime) 0.upto(9) do |repeating_number| # Assume mask of 3 or more repeating numbers if prime.count(repeating_number.to_s) >= 3 ctr = 1 (repeating_number + 1).upto(9) do |replacement_number| family_candidate = prime.gsub(repeating_number.to_s, replacement_number.to_s) ctr += 1 if (family_candidate.to_i).prime? end return true if ctr >= 8 end end false end # Wanted to loop through primes using Prime.each # but it took too long to get to the starting value. n = 9999 while n += 2 next if !n.prime? break if eight_prime_family(n.to_s) end puts n puts "Elapsed Time: #{(Time.now - timer_start)*1000} milliseconds"

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• When Do OS Questions Belong on Hardware Service Requests?

  - by Get Proactive Customer Adoption Team

  Untitled Document My Oracle Support—Logging an Operating System Service Request One of the concerns we hear from our customers with Premier Support for Systems is that they have difficulty logging a Service Request (SR) for an operating system issue. Because Premier Support for Systems includes support for the hardware and the associated operating system, you log any operating system issues through a hardware Service Request. To create a hardware Service Request, you enter the information into the Hardware tab of the Create Service Request screen, but to ensure that the hardware Service Request you enter is recognized and routed appropriately for an operating system issue, you need to change the product from your specific hardware to the operating system that the hardware is running. The example below shows you how to create a Service Request for the operating system when the support level is Premier Support for Systems. The key to success is remembering that the operating system coverage is part of the hardware support. To begin, from anywhere within My Oracle Support, click on the Create SR button as you would to log any SR: Enter your Problem Summary and the Problem Description Next, click on the Hardware tab. Enter the System Serial Number (in this case “12345”) and click on Validate Serial Number: Notice that the product name for the hardware indicates “Sunfire T2000 Server” with an option for a drop down List of Values. Click on the product drop down and choose the correct operating system from the list. In this case I have chosen “OpenSolaris Operating System” Next, you will need to enter the correct operating system version: At this point, you may proceed to complete and submit the Service Request. If your company has Premier Support for Systems, just remember that your operating system has coverage under the hardware it runs on, so start with a Hardware tab on the Service Request screen and change the product related information to reflect the operating system you need help with. Following these simple steps will ensure that the system assigns your Service Request to the right support team for an operating system issue and the support engineer can quickly begin working your issue.

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• Is copy paste programming bad ?

  - by ring bearer

  With plain google as well as google code search tools it is easy to find how to program using some resource or solve certain problems ( such as a Java class, or a ftp block in perl etc) and so developers are so tempted to just purely copy paste the code (in a way re-use) - is this an incompetency? I have done this myself though I think I am a better programmer than many others I have seen. Who has the time to RTFM? In this age of information abundance, I do not think that copy paste programming is bad. Isn't that what sites like stackoverflow do anyway? People ask - ok here is my problem - how to solve it? now someone will post complete code and the person who asked the question would simply copy paste the most voted answer. No matter how small the problem is. I am working with a bunch of young coders who heavily rely on internet to get their job done. I see convenience (for example, you may be quite good with algorithms and such but you may not know how to use a BufferedReader in Java - would you read complete Javadoc for BufferedReader or look up some example of using it somewhere??) in copy pasting and modifying code to get the job done. What are the real dangers of copy paste coding that can impact their competency?

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• Better Understand the 'Strategy' Design Pattern

  - by Imran Omar Bukhsh

  Greetings Hope you all are doing great. I have been interested in design patterns for a while and started reading 'Head First Design Patterns'. I started with the first pattern called the 'Strategy' pattern. I went through the problem outlined in the images below and first tried to propose a solution myself so I could really grasp the importance of the pattern. So my question is that why is my solution ( below ) to the problem outlined in the images below not good enough. What are the good / bad points of my solution vs the pattern? What makes the pattern clearly the only viable solution ? Thanks for you input, hope it will help me better understand the pattern. MY SOLUTION Parent Class: DUCK <?php class Duck { public $swimmable; public $quackable; public $flyable; function display() { echo "A Duck Looks Like This<BR/>"; } function quack() { if($this->quackable==1) { echo("Quack<BR/>"); } } function swim() { if($this->swimmable==1) { echo("Swim<BR/>"); } } function fly() { if($this->flyable==1) { echo("Fly<BR/>"); } } } ?> INHERITING CLASS: MallardDuck <?php class MallardDuck extends Duck { function MallardDuck() { $this->quackable = 1; $this->swimmable = 1; } function display() { echo "A Mallard Duck Looks Like This<BR/>"; } } ?> INHERITING CLASS: WoddenDecoyDuck <?php class WoddenDecoyDuck extends Duck { function woddendecoyduck() { $this->quackable = 0; $this->swimmable = 0; } function display() { echo "A Wooden Decoy Duck Looks Like This<BR/>"; } } Thanking you for your input. Imran

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• Profile of Scott L Newman

  - by Ratman21

  To:       Whom It May Concern From: Scott L Newman Date:   4/23/2010 Re:      Profile Who is he, what can he do? Two very good questions. #1. I am a 20 + years experience Information Technology Professional (hold on don’t hit delete yet!). Who is not over the hill (I am on top of it) and still knows how to do (and can still do) that thing call work! #2. A can do attitude, that does not allow problems to sit unfixed. I have a broad range of skills, including: Certified CompTIA A+, Security+ and Network+ Technician §         2.5 years (NOC) Network experience on large Cisco based Wan – UK to Austria §         20 years experience MIS/DP – Yes I can do IBM mainframes and Tandem non-stops too §         18 years experience as technical Help Desk support – panicking users, no problem §         18 years experience with PC/Server based system, intranet and internet systems §         10+ years experienced on: Microsoft Office, Windows XP and Data Network Fundamentals (YES I do windows) §         Strong trouble shooting skills for software, hard ware and circuit issues (and I can tell you what kind of horrors I had to face on all of them). §         Very experienced on working with customers on problems – again panicking users, no problem §         Working experience with Remote Access (VPN/SecurID) – I didn’t just study them I worked on/with them §         Skilled in getting info for and creating documentation for Operation procedures (I do not just wait for them to give it to me I go out and get it. Waiting for info on working applications is, well dumb) Multiple software languages (Hey I have done some programming) And much more experiences in “IT” (Mortgage, stocks and financial information systems experience and have worked “IT” in a hospital) Can multitask, also have ability to adapt to change and learn quickly. (once was put in charge of a system that I had not worked with for over two years. Talk about having to relearn and adapt to changes fast. But I did it.)   The summarization is that I know what do, know keep things going and how to fix it when it breaks.   Scott L. Newman Confidential

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• Finetuning movement based on gradual rotation towards a target

  - by A.B.

  I have an object which moves towards a target destination by gradually adjusting its facing while moving forwards. If the target destination is in a "blind spot", then the object is incapable of reaching it. This problem is ilustrated in the picture below. When the arrow is ordered to move to point A, it will only end up circling around it (following the red circle) because it is not able to adjust its rotation quickly enough. I'm interested in a solution where the movement speed is multiplied by a number from 0.1 to 1 in proportion to necessity. The problem is, how do I calculate whether it is necessary in the first place? How do I calculate an appropriate multiplier that is neither too small nor too large? void moveToPoint(sf::Vector2f destination) { if (destination == position) return; auto movement_distance = distanceBetweenPoints(position, destination); desired_rotation = angleBetweenPoints(position, destination); /// Check whether rotation should be adjusted if (rotation != desired_rotation) { /// Check whether the object can achieve the desired rotation within the next adjustment of its rotation if (Radian::isWithinDistance(rotation, desired_rotation, rotation_speed)) { rotation = desired_rotation; } else { /// Determine whether to increment or decrement rotation in order to achieve desired rotation if (Radian::convert(desired_rotation - rotation) > 0) { /// Increment rotation rotation += rotation_speed; } else { /// Decrement rotation rotation -= rotation_speed; } } } if (movement_distance < movement_speed) { position = destination; } else { position.x = position.x + movement_speed*cos(rotation); position.y = position.y + movement_speed*sin(rotation); } updateGraphics(); }

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• Following the Thread in OSB

  - by Antony Reynolds

  Threading in OSB The Scenario I recently led an OSB POC where we needed to get high throughput from an OSB pipeline that had the following logic: 1. Receive Request 2. Send Request to External System 3. If Response has a particular value   3.1 Modify Request   3.2 Resend Request to External System 4. Send Response back to Requestor All looks very straightforward and no nasty wrinkles along the way.  The flow was implemented in OSB as follows (see diagram for more details): Proxy Service to Receive Request and Send Response Request Pipeline   Copies Original Request for use in step 3 Route Node   Sends Request to External System exposed as a Business Service Response Pipeline   Checks Response to Check If Request Needs to Be Resubmitted Modify Request Callout to External System (same Business Service as Route Node) The Proxy and the Business Service were each assigned their own Work Manager, effectively giving each of them their own thread pool. The Surprise Imagine our surprise when, on stressing the system we saw it lock up, with large numbers of blocked threads.  The reason for the lock up is due to some subtleties in the OSB thread model which is the topic of this post.   Basic Thread Model OSB goes to great lengths to avoid holding on to threads.  Lets start by looking at how how OSB deals with a simple request/response routing to a business service in a route node. Most Business Services are implemented by OSB in two parts.  The first part uses the request thread to send the request to the target.  In the diagram this is represented by the thread T1.  After sending the request to the target (the Business Service in our diagram) the request thread is released back to whatever pool it came from.  A multiplexor (muxer) is used to wait for the response.  When the response is received the muxer hands off the response to a new thread that is used to execute the response pipeline, this is represented in the diagram by T2. OSB allows you to assign different Work Managers and hence different thread pools to each Proxy Service and Business Service.  In out example we have the “Proxy Service Work Manager” assigned to the Proxy Service and the “Business Service Work Manager” assigned to the Business Service.  Note that the Business Service Work Manager is only used to assign the thread to process the response, it is never used to process the request. This architecture means that while waiting for a response from a business service there are no threads in use, which makes for better scalability in terms of thread usage. First Wrinkle Note that if the Proxy and the Business Service both use the same Work Manager then there is potential for starvation.  For example: Request Pipeline makes a blocking callout, say to perform a database read. Business Service response tries to allocate a thread from thread pool but all threads are blocked in the database read. New requests arrive and contend with responses arriving for the available threads. Similar problems can occur if the response pipeline blocks for some reason, maybe a database update for example. Solution The solution to this is to make sure that the Proxy and Business Service use different Work Managers so that they do not contend with each other for threads. Do Nothing Route Thread Model So what happens if there is no route node?  In this case OSB just echoes the Request message as a Response message, but what happens to the threads?  OSB still uses a separate thread for the response, but in this case the Work Manager used is the Default Work Manager. So this is really a special case of the Basic Thread Model discussed above, except that the response pipeline will always execute on the Default Work Manager.   Proxy Chaining Thread Model So what happens when the route node is actually calling a Proxy Service rather than a Business Service, does the second Proxy Service use its own Thread or does it re-use the thread of the original Request Pipeline? Well as you can see from the diagram when a route node calls another proxy service then the original Work Manager is used for both request pipelines.  Similarly the response pipeline uses the Work Manager associated with the ultimate Business Service invoked via a Route Node.  This actually fits in with the earlier description I gave about Business Services and by extension Route Nodes they “… uses the request thread to send the request to the target”. Call Out Threading Model So what happens when you make a Service Callout to a Business Service from within a pipeline.  The documentation says that “The pipeline processor will block the thread until the response arrives asynchronously” when using a Service Callout.  What this means is that the target Business Service is called using the pipeline thread but the response is also handled by the pipeline thread.  This implies that the pipeline thread blocks waiting for a response.  It is the handling of this response that behaves in an unexpected way. When a Business Service is called via a Service Callout, the calling thread is suspended after sending the request, but unlike the Route Node case the thread is not released, it waits for the response.  The muxer uses the Business Service Work Manager to allocate a thread to process the response, but in this case processing the response means getting the response and notifying the blocked pipeline thread that the response is available.  The original pipeline thread can then continue to process the response. Second Wrinkle This leads to an unfortunate wrinkle.  If the Business Service is using the same Work Manager as the Pipeline then it is possible for starvation or a deadlock to occur.  The scenario is as follows: Pipeline makes a Callout and the thread is suspended but still allocated Multiple Pipeline instances using the same Work Manager are in this state (common for a system under load) Response comes back but all Work Manager threads are allocated to blocked pipelines. Response cannot be processed and so pipeline threads never unblock – deadlock! Solution The solution to this is to make sure that any Business Services used by a Callout in a pipeline use a different Work Manager to the pipeline itself. The Solution to My Problem Looking back at my original workflow we see that the same Business Service is called twice, once in a Routing Node and once in a Response Pipeline Callout.  This was what was causing my problem because the response pipeline was using the Business Service Work Manager, but the Service Callout wanted to use the same Work Manager to handle the responses and so eventually my Response Pipeline hogged all the available threads so no responses could be processed. The solution was to create a second Business Service pointing to the same location as the original Business Service, the only difference was to assign a different Work Manager to this Business Service.  This ensured that when the Service Callout completed there were always threads available to process the response because the response processing from the Service Callout had its own dedicated Work Manager. Summary Request Pipeline Executes on Proxy Work Manager (WM) Thread so limited by setting of that WM.  If no WM specified then uses WLS default WM. Route Node Request sent using Proxy WM Thread Proxy WM Thread is released before getting response Muxer is used to handle response Muxer hands off response to Business Service (BS) WM Response Pipeline Executes on Routed Business Service WM Thread so limited by setting of that WM.  If no WM specified then uses WLS default WM. No Route Node (Echo functionality) Proxy WM thread released New thread from the default WM used for response pipeline Service Callout Request sent using proxy pipeline thread Proxy thread is suspended (not released) until the response comes back Notification of response handled by BS WM thread so limited by setting of that WM.  If no WM specified then uses WLS default WM. Note this is a very short lived use of the thread After notification by callout BS WM thread that thread is released and execution continues on the original pipeline thread. Route/Callout to Proxy Service Request Pipeline of callee executes on requestor thread Response Pipeline of caller executes on response thread of requested proxy Throttling Request message may be queued if limit reached. Requesting thread is released (route node) or suspended (callout) So what this means is that you may get deadlocks caused by thread starvation if you use the same thread pool for the business service in a route node and the business service in a callout from the response pipeline because the callout will need a notification thread from the same thread pool as the response pipeline.  This was the problem we were having. You get a similar problem if you use the same work manager for the proxy request pipeline and a business service callout from that request pipeline. It also means you may want to have different work managers for the proxy and business service in the route node. Basically you need to think carefully about how threading impacts your proxy services. References Thanks to Jay Kasi, Gerald Nunn and Deb Ayers for helping to explain this to me.  Any errors are my own and not theirs.  Also thanks to my colleagues Milind Pandit and Prasad Bopardikar who travelled this road with me. OSB Thread Model Great Blog Post on Thread Usage in OSB

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• Platform Builder: PBWorkspaces CESysgen.bat Not Used?

  - by Bruce Eitman

  One of the things that I like about Windows CE is that I am always learning new things, but in this case it is a bit disturbing. We working with Multi UI (MUI) this week and discovered some problems with Windows CE 5.0 and Chinese language support. These problems don’t exist in CE 6.0. The problem was that in the batch files in Public\CEBASE\oak\misc, specifically weceshellfe.bat, some of the shell components needed are only included if certain LOCALs are selected. English is not one of them, I suppose this is because someone didn’t think that we would ever use them and English – doh. No problem, just work around this in PBWorkspaces\<workspace>\WINCE500\<BPS>\cesysgen.bat. But that didn’t work. After a lot of trial and error, what I determined is that this cesysgen.bat isn’t actually used by Platform Builder any more.  Instead, in that same folder is a <workspace>.bat file that is called by Public\CEBASE\oak\misc\cesysgen.bat. That leads to some new problems though, but solvable, in that what I really wanted to do was add a fix after the batch files in CEBASE run, but <workspace>.bat runs before the other batch files in CEBASE. So what I finally came up with was to add the fix to the PASS2 handling in <workspace>.bat. Copyright © 2010 – Bruce Eitman All Rights Reserved

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• 2D character controller in unity (trying to get old-school platformers back)

  - by Notbad

  This days I'm trying to create a 2D character controller with unity (using phisics). I'm fairly new to physic engines and it is really hard to get the control feel I'm looking for. I would be really happy if anyone could suggest solution for a problem I'm finding: This is my FixedUpdate right now: public void FixedUpdate() { Vector3 v=new Vector3(0,-10000*Time.fixedDeltaTime,0); _body.AddForce(v); v.y=0; if(state(MovementState.Left)) { v.x=-_walkSpeed*Time.fixedDeltaTime+v.x; if(Mathf.Abs(v.x)>_maxWalkSpeed) v.x=-_maxWalkSpeed; } else if(state(MovementState.Right)) { v.x= _walkSpeed*Time.fixedDeltaTime+v.x; if(Mathf.Abs(v.x)>_maxWalkSpeed) v.x=_maxWalkSpeed; } _body.velocity=v; Debug.Log("Velocity: "+_body.velocity); } I'm trying here to just move the rigid body applying a gravity and a linear force for left and right. I have setup a physic material that makes no bouncing and 0 friction when moving and 1 friction with stand still. The main problem is that I have colliders with slopes and the velocity changes from going up (slower) , going down the slope (faster) and walk on a straight collider (normal). How could this be fixed? As you see I'm applying allways same velocity for x axis. For the player I have it setup with a sphere at feet position that is the rigidbody I'm applying forces to. Any other tip that could make my life easier with this are welcomed :). P.D. While coming home I have noticed I could solve this applying a constant force parallel to the surface the player is walking, but don't know if it is best method.

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• Oracle 64-bit assembly throws BadImageFormatException when running unit tests

  - by pjohnson

  We recently upgraded to the 64-bit Oracle client. Since then, Visual Studio 2010 unit tests that hit the database (I know, unit tests shouldn't hit the database--they're not perfect) all fail with this error message:Test method MyProject.Test.SomeTest threw exception: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.BadImageFormatException: Could not load file or assembly 'Oracle.DataAccess, Version=4.112.3.0, Culture=neutral, PublicKeyToken=89b483f429c47342' or one of its dependencies. An attempt was made to load a program with an incorrect format.I resolved this by changing the test settings to run tests in 64-bit. From the Test menu, go to Edit Test Settings, and pick your settings file. Go to Hosts, and change the "Run tests in 32 bit or 64 bit process" dropdown to "Run tests in 64 bit process on 64 bit machine". Now your tests should run.This fix makes me a little nervous. Visual Studio 2010 and earlier seem to change that file for no apparent reason, add more settings files, etc. If you're not paying attention, you could have TestSettings1.testsettings through TestSettings99.testsettings sitting there and never notice the difference. So it's worth making a note of how to change it in case you have to redo it, and being vigilant about files VS tries to add.I'm not entirely clear on why this was even a problem. Isn't that the point of an MSIL assembly, that it's not specific to the hardware it runs on? An IL disassembler can open the Oracle.DataAccess.dll in question, and in its Runtime property, I see the value "v4.0.30319 / x64". So I guess the assembly was specifically build to target 64-bit platforms only, possibly due to a 64-bit-specific difference in the external Oracle client upon which it depends. Most other assemblies, especially in the .NET Framework, list "msil", and a couple list "x86". So I guess this is another entry in the long list of ways Oracle refuses to play nice with Windows and .NET.If this doesn't solve your problem, you can read others' research into this error, and where to change the same test setting in Visual Studio 2012.

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• No USB 04b4:0307 mike input after 10.04

  - by Papou

  I am using an USB phone that is in fact a so-called "sound card" based on the 04b4:0307 chip. In fact, I have two different phones using 04b4:0307 and in fact I have a sound USB key too. This, I believe, is the start of why they call 04b4:0307 "ubiquitous" (instead of oh four bee...). But not "eternal". The mike worked in Ubuntu 9.10 and 10.04 but not later ([email protected]). "not working" means that 04b4:0307 shows in Sound Preference but that its vu-meter is mute. I have posted the full lsusb and the result of tests in various systems here: http://www.papou.byethost9.com/tmp/1043601.html Note: Tests done on VirtualBox (thankfully). But UbuntUnity no longer works on VB, so I used the LinuxMint equivalent. ?hat's fate. I could not find any problem report close enough. What should be my next step? I believe the problem occurs in module snd-usb-audio. One thing I might try if I knew how is hacking a DEB with its 10.04's source. I can hack DEBs. Any hint welcome on how to make a DEB overriding a kernel packed module. I mean that the newly installed module should have precedence, be loaded instead, the module installed with the kernel. TIA !

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• How to login as other in ubuntu 12.04

  - by murali

  i have upgraded my ubuntu 11.10 to 12.04. i could not see other login option in the login screen. it shows only Guest login and User login. The User Login ask only password and i had never entered in as User login so that i do not know about password of User login. my problem is how to login as root from the login screen? how can i get Other login option to login as root or some other user? before ask this question i have tried the following: try to add the greeter-show-manual-login=true line at the bottom of /etc/lightdm/lightdm.conf file as Guest login but i get access denied error. i do not know the password of User login (ask only password while login) to purpose of adding above line. from the safe mode login, i could login as root but i could not add the above line the lightdm.conf file . i got read only error so that i tried to change the permission to 777 like the following > chmod 777 lightdm.conf (i am within the /etc/lightdm/). but i got the error the file marked as/is read only in the file system. In 11.10 version i have created 4 users. i can see that the users exist in 12.10 . so i am sure my self users are not removed while upgrate. In short, i need Other login option on my login screen? how to get it? please help me. * Edited Question:* i have add the following line the /etc/lightdm/lighdm.conf file on recovery mode greeter-show-manual-login=true and i saved the file using wq command. now my /etc/lightdm/lighdm.conf file looking as the following: [SeatDefaults] greeter-session=unity-greeter user-session=ubuntu greeter-show-manual-login=true if i commit any mistake please correct me. by this problem i have wasted the two working day and all the works are in pending... please help me.

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• ArchBeat Link-o-Rama for 2012-03-16

  - by Bob Rhubart

  Applications Architecture | Roy Hunter and Brian Rasmussen www.oracle.com Roy Hunter and Brian Rasmussen examine the strategies three organizations applied to modernize their application architectures. Part of the Oracle Experiences in Enterprise Architecture article series. Public Sector Architecture | Jeremy Foreman and Hamza Jahangir www.oracle.com Jeremy Foreman and Hamza Jahangir examine the strategies used by two different organizations in deploying their respective future-state architectures. Part of the Oracle Experiences in Enterprise Architecture article series. XMLA vs BAPI | Sunil S. Ranka sranka.wordpress.com Oracle ACE Sunil Ranka's brief primer on the XMLA and BAPI standards. The Java EE 6 Example - Running Galleria on WebLogic 12 - Part 3 | Markus Eisele blog.eisele.net Oracle ACE Director Markus Eisele continues his series on working with Galleria. Oracle Linux Online Forum - March 27 event.on24.com Date: Tuesday, March 27, 2012 Time: 9:30 AM PT / 12:30 PM ET Hosts: Oracle Executives Edward Screven and Wim Coekaerts. Customer Presentation: How Oracle Helps Reduce Cost and Improve Performance of Database Applications at Progressive Insurance Speaker: John Dome What's New in Oracle Linux Speakers: Waseem Daher, Chris Mason, Elena Zannoni, Lenz Grimmer Get More Value from your Linux Vendor Speakers: Sergio Leunissen, Chris Mason, Monica Kumar JavaOne 2012 Call for Papers www.oracle.com Don't keep all that Java skill locked up in your overstuffed cranium. Submit your proposal for that killer paper now to share your experience at this year’s JavaOne. Running applications in the cloud are not designed for the cloud | Tom Laszewski blogs.oracle.com "The issue you face with moving client/server applications to the cloud via rehosting is 'where will the applications run?'" says Tom Laszewski. GlassFish 3.1.2 - Which Platform(s)? | The Aquarium blogs.oracle.com The Aquarium shares a list of GlassFish 3.1.2-supported operating systems and JVMs. IT Strategies from Oracle; Three Recipes for Oracle Service Bus 11g ; Stir Up Some SOA www.oracle.com Featured this week on the OTN Architect Portal, along with the latest events, product downloads, community social resources, articles on hot topics, and a whole lot more. Thought for the Day "No matter what the problem is, it's always a people problem." — Gerald M. Weinberg

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• Big Data for Retail

  - by David Dorf

  Right up there with mobile, social, and cloud is the term "big data," which seems to be popping up lots in the press these days.  Companies like Google, Yahoo, and Facebook have popularized a new class of data technologies meant to solve the problem of processing large amounts of data quickly.  I first mentioned this in a posting back in March 2009.  Put simply, big data implies datasets so large they can't normally be processed using a standard transactional database.  The term "noSQL" is often used in this context as well. Actually, using parallel processing within the Oracle database combined with Exadata can achieve impressive results.  Look for more from Oracle at OpenWorld as hinted by Jean-Pierre Dijcks. McKinsey recently released a report on big data in which retail was specifically mentioned as an industry that can benefit from the new technologies.  I won't rehash that report because my friend Rama already did such a good job in his posting, Impact of "Big Data" on Retail. The presentation below does a pretty good job of framing the problem, although it doesn't really get into the available technologies (e.g. Exadata, Hadoop, Cassandra, etc.) and isn't retail specific. Determine the Right Analytic Database: A Survey of New Data Technologies So when a retailer asks me about big data, here's what I say:  Big data refers to a set of technologies for processing large volumes of structured and unstructured data.  Imagine collecting everything uttered by your customers on Facebook and Twitter and combining it with all the data you can find about the products you sell (e.g. reviews, images, demonstration videos), including competitive data.  Assuming you could process all that data, you could then personalize offers to specific customers based on their tastes, ensure prices are competitive, and implement better local assortments.  It's really not that far off.

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• dpkg: error: parsing file '/var/lib/dpkg/status' near line 6449

  - by mpole

  Good evening. This problem occured when trying to update using the update manager. A problem occured so I cleared all the cache and tried to update once again this time in terminal, and it spat out: dpkg: error: parsing file '/var/lib/dpkg/status' near line 6449 missing package name After opening up 'status' with gedit and going to line 6449, I found that nothing was on that line but the following was before and after it. This package contains the Mono System.Configuration library for CLI 4.0. Original-Maintainer: Debian Mono Group <[email protected])oth.debian.org> Homepage: http://www.mono-project.com/ <<<<---- LINE 6449 Package: bzip2 Status: install ok installed Priority: optional Section: utils Installed-Size: 160 Maintainer: Ubuntu Developers <[email protected]> <<<<--- LINE 6449 is obviously not on the file, but I can't see whats wrong here? anybody have an idea? Thanks! Edit: I have tried running: sudo apt-get install --fix-missing sudo dpkg --clear-avail But no good...

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• When SharePoint Designer has its own designs

  - by PeterBrunone

  Recently, a colleague came to me with a simple task and an inscrutable error.  He just wanted to populate a text field with a querystring value.  If you've ever done this in SPD, you know it's fairly simple:  create a parameter, map it to a querystring value, and then use the resulting parameter name in your form field. Having done so, however, he was told the following by the ASP.NET "yellow barf page": The 'Text' property of 'asp:TextBox' does not allow child objects. As it turns out, he had done everything correctly.  The problem was that SharePoint Designer had decided the best place for his FieldDescription control was INSIDE the TextBox control.  Obviously the compiler doesn't know what to do with that.  When the FieldDescription was moved to a less obtrusive location, everything worked as expected.The moral of the story is, as always, don't trust what any WYSIWYG tool gives you.  If it looks great, then fine.  However, if there's a problem, remember that Design mode was written by human beings who make mistakes... just like the rest of us.Take THAT, Skynet.

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• Scheduling of jobs in the presence of constraints in Java

  - by Asgard

  I want to know how to implement a solution to this problem: A task is performed by running, by more people, some basic jobs with known duration in time units (days, months, etc..). The execution of the jobs could lead to the existence of time constraints: a job, for example, can not start if it is not over another (or others) and so on. I want to design and build an application to check the correctness of jobs activities and to propose a schedule of jobs, if any, which is respectful of the constraints. Input must provide the jobs and associated constraints. The expected output is the scheduling of jobs. The specification of an elementary job consists of the pair <jobs-id, duration> A constraint is expressed by means of a quintuple of the type <S/E, id-job1, B/A, S/E, id-job2> the beginning (S) or the end (E) of a jobs Id-job1, must take place before (B) / after (A) of the beginning (S) / end (E) of the Id-job2. If there are no dependencies between some jobs, then jobs can be done before, in parallel. As a simple example, consider the input: jobs jobs(0, 3) jobs(1, 4) jobs(2, 5) jobs(3, 3) jobs(4, 3) constraints constraints(S, 1, A, E, 0) constraints(S, 4, A, E, 2) Possible output: t 0 1 2 3 4 0 * - * * - 1 * - * * - 2 * - * * - 3 * - * * - 4 - * * - - 5 - * * - - 6 - * - - * 7 - * - - * 8 - * - - * 9 - - - - * How to code an efficient java scheduler(avoiding the intense backtracking if is possible) to manage the jobs with these constraints, as described??? I have seen a discussion on a thread in a forum where an user seems has solved the problem easily, but He haven't given enough details to the users to compile a working project(I'm noob), and I'm interested to know an effective implementation of the solution (without using external libraries). If someone help me, I'll give to him a very good feedback ;)

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• Visual Studio ALM MVP of the Year 2011

  - by Martin Hinshelwood

  For some reason this year some of my peers decided to vote for me as a contender for Visual Studio ALM MVP of the year. I am not sure what I did to deserve this, but a number of people have commented that I have a rather useful blog. I feel wholly unworthy to join the ranks of previous winners: Ed Blankenship (2010) Martin Woodward (2009) Thank you to everyone who voted regardless of who you voted for. If there was a prize for the best group of MVP’s then the Visual Studio ALM MVP would be a clear winner, as would the product group of product groups that is Visual Studio ALM Group. To use a phrase that I have learned since moving to Seattle and probably use too much: you guys are all just awesome. I have tried my best in the last year to document not only every problem that I have had with Team Foundation Server (TFS), but also to document as many of the things I am doing as possible. I have taken some of Adam Cogan’s rules to heart and when a customer asks me a question I always blog the answer and send them a link. This allows both my blog and my understanding of TFS to grow while creating a useful bank of content. The idea is that if one customer asks, all benefit. I try, when writing for my blog, to capture both the essence and the context for a problem being solved. This allows more people to benefit as they do not need to understand the specifics of an environment to gain value. I have a number of goals for this year that I think will help increase value in the community: persuade my new colleagues at Northwest Cadence to do more blogging (Steve, Jeff, Shad and Rennie) Rangers Project – TFS Iteration Automation with Willy-Peter Schaub, Bill Essary, Martin Hinshelwood, Mike Fourie, Jeff Bramwell and Brian Blackman Write a book on the Team Foundation Server API with Willy-Peter Schaub, Mike Fourie and Jeff Bramwell write more useful blog posts I do not think that these things are beyond the realms of do-ability, but we will see…

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• How do you deal with translating theory into practice?

  - by Mr. Shickadance

  Hello all! Being a computer scientist in a research field I am often tasked with working alongside professionals outside of the software domain (think math people, electrical engineer etc), and then translating their theories and ideas into real-world implementations. I often find it difficult when they present a theoretical problem which appears to be somewhat disconnected from reality. I am not saying that the theory is bogus, only that it is difficult to translate into real-world situations. For example, recently I have been working with software defined radios. We are exploring many different areas, but often the math specialists in my group would present a problem which is heavily grounded in theory (signal processing, physics, whatever). I often struggle at times where it is hard to draw direct parallels between the theory and the real-world implementation that I need to develop. Say we are working on an energy detector, the theory person in my group would say "you need to measure the noise variance with no signal present." This leads me to think "how the hell do I isolate noise from a signal in reality?" There are many examples, but I hope you see where I am going. So, my question is how does one deal with implementation of theoretical concepts when the theory seems detached from reality? Or at least when the connections are not so clear. Or perhaps, the person with the 'theory' may be ignorant of real restrictions? Note: I found this to be a hard question to ask - hopefully you are following me. If you have suggestions on how I could improve it, by all means let me know! Thanks for looking! EDIT: To be a bit more clear, I understand in situations like this that I must learn that specific domain myself to an extent (i.e. signal processing), but I am more concerned with when those theoretical concepts do not appear to be as grounded in practice as one would like.

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• Silverlight Cream for June 12, 2010 -- #880

  - by Dave Campbell

  In this Issue: Michael Washington, Diego Poza, Viktor Larsson, Brian Noyes, Charles Petzold, Laurent Bugnion, Anjaiah Keesari, David Anson, and Jeremy Likness. From SilverlightCream.com: My MEF Rant Read Michael Washington's discussion about MEF from someone that's got some experience, but not enough to remember the pain points... how it works, and what he'd like to see. Prism 4: What’s new and what’s next Diego Poza Why Office Hub is important for WP7 Viktor Larsson has another WP7 post up and he's talking about the Office Hub ... good description and maybe the first I've seen on the Office Hub. WCF RIA Services Part 1: Getting Started Brian Noyes has part 1 of a 10-part tutorial series on WCF RIA Services up at SilverlightShow. This first is the intro, but it's a good one. CompositionTarget.Rendering and RenderEventArgs Charles Petzold talks about CompositionTarget.Rendering and using it for calculating time span ... and it works in WPF and WP7 too... cool example from his WPF book, and all the code. Two small issues with Windows Phone 7 ApplicationBar buttons (and workaround) Laurent Bugnion has a post up from earlier this week that I missed describing problems with the WP7 ApplicationBar ... oh, and a workaround for it :) Animation in Silverlight Anjaiah Keesari has a really extensive post up on Silverlight animation, and this is an all-XAML thing... so buckle up we're going old-school :) Two fixes for my Silverlight SplitButton/MenuButton implementation - and true WPF support David Anson revisits and revises his SplitButton code based on a couple problem reports he received. Source for the button and the test project is included. Tips and Tricks for INotifyPropertyChanged Jeremy Likness is discussing INotifyPropertyChanged and describes an extension method. He does bring up a problem associated with this, so check that out. He finishes the post off with a discussion of "Observable Enumerables" Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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• Help implementing virtual d-pad

  - by Moshe

  Short Version: I am trying to move a player around on a tilemap, keeping it centered on its tile, while smoothly controlling it with SneakyInput virtual Joystick. My movement is jumpy and hard to control. What's a good way to implement this? Long Version: I'm trying to get a tilemap based RPG "layer" working on top of cocos2d-iphone. I'm using SneakyInput as the input right now, but I've run into a bit of a snag. Initially, I followed Steffen Itterheim's book and Ray Wenderlich's tutorial, and I got jumpy movement working. My player now moves from tile to tile, without any animation whatsoever. So, I took it a step further. I changed my player.position to a CCMoveTo action. Combined with CCfollow, my player moves pretty smoothly. Here's the problem, though: Between each CCMoveTo, the movement stops, so there's a bit of a jumpiness introduced between movements. To deal with that, I changed my CCmoveTo into a CCMoveBy, and instead of running it once, I decided to have it CCRepeatForever. My plan was to stop the repeating action whenever the player changed directions or released the d-pad. However, when the movement stops, the player is not necessarily centered along the tiles, as it should be. To correctly position the player, I use a CCMoveTo and get the closest position that would put the player back into the proper position. This reintroduces an earlier problem of jumpiness between actions. What is the correct way to implement a smooth joystick while smoothly animating the player and keeping it on the "grid" of tiles? Edit: It turns out that this was caused by a "Bug Fix" in the cocos2d engine.

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• crash when using wireless network

  - by Erik

  ubuntu 12.04 32 bit When I start up my system almost instantly freezes, I found that the problem lays with my wireless network, because the crash is always t the same time as the message that tells me I am connected to a network when I start up connected to a cable everything works fine, I can even see that I am connected to our wireless network, until I unplug the ethernet cable, then it all freezes again the same happened when I boot from a live cd (from usb) The problem only occurs on my netbook, my laptop doesn't give any problems. I don't know if anyone else has had similar problems, or if anyone knows a solution... Thanks in advance! greetings Erik EDIT (21/3/2012): it seems there is some external factor involved, I'm using my netbook for about 50 minutes now while connected to the wireless network, and still it didn't crash strange enough, before these 50 minutes I had to put it down by holding the power button, because I decided to try it again, that time it did crash... before (while connected with an ethernet cable) I've been trying to get my Bluetooth working, that didn't succeed entirely, but I guess that might be a factor in the question why it doesn't crash at the moment now I rebooted, connected, and no crash... if it crashes again, I'll update this post again. in the meantime, if anyone has an idea on what could be a factor, and on how to create a crash using that factor, feel free to ask!

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