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• MVP in 2010

  Microsoft has just named me an MVP for the seventh time in a row!More .NET adventures with me expected in 2010......Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• The blocking nature of aggregates

  - by Rob Farley

  I wrote a post recently about how query tuning isn’t just about how quickly the query runs – that if you have something (such as SSIS) that is consuming your data (and probably introducing a bottleneck), then it might be more important to have a query which focuses on getting the first bit of data out. You can read that post here.  In particular, we looked at two operators that could be used to ensure that a query returns only Distinct rows. and The Sort operator pulls in all the data, sorts it (discarding duplicates), and then pushes out the remaining rows. The Hash Match operator performs a Hashing function on each row as it comes in, and then looks to see if it’s created a Hash it’s seen before. If not, it pushes the row out. The Sort method is quicker, but has to wait until it’s gathered all the data before it can do the sort, and therefore blocks the data flow. But that was my last post. This one’s a bit different. This post is going to look at how Aggregate functions work, which ties nicely into this month’s T-SQL Tuesday. I’ve frequently explained about the fact that DISTINCT and GROUP BY are essentially the same function, although DISTINCT is the poorer cousin because you have less control over it, and you can’t apply aggregate functions. Just like the operators used for Distinct, there are different flavours of Aggregate operators – coming in blocking and non-blocking varieties. The example I like to use to explain this is a pile of playing cards. If I’m handed a pile of cards and asked to count how many cards there are in each suit, it’s going to help if the cards are already ordered. Suppose I’m playing a game of Bridge, I can easily glance at my hand and count how many there are in each suit, because I keep the pile of cards in order. Moving from left to right, I could tell you I have four Hearts in my hand, even before I’ve got to the end. By telling you that I have four Hearts as soon as I know, I demonstrate the principle of a non-blocking operation. This is known as a Stream Aggregate operation. It requires input which is sorted by whichever columns the grouping is on, and it will release a row as soon as the group changes – when I encounter a Spade, I know I don’t have any more Hearts in my hand. Alternatively, if the pile of cards are not sorted, I won’t know how many Hearts I have until I’ve looked through all the cards. In fact, to count them, I basically need to put them into little piles, and when I’ve finished making all those piles, I can count how many there are in each. Because I don’t know any of the final numbers until I’ve seen all the cards, this is blocking. This performs the aggregate function using a Hash Match. Observant readers will remember this from my Distinct example. You might remember that my earlier Hash Match operation – used for Distinct Flow – wasn’t blocking. But this one is. They’re essentially doing a similar operation, applying a Hash function to some data and seeing if the set of values have been seen before, but before, it needs more information than the mere existence of a new set of values, it needs to consider how many of them there are. A lot is dependent here on whether the data coming out of the source is sorted or not, and this is largely determined by the indexes that are being used. If you look in the Properties of an Index Scan, you’ll be able to see whether the order of the data is required by the plan. A property called Ordered will demonstrate this. In this particular example, the second plan is significantly faster, but is dependent on having ordered data. In fact, if I force a Stream Aggregate on unordered data (which I’m doing by telling it to use a different index), a Sort operation is needed, which makes my plan a lot slower. This is all very straight-forward stuff, and information that most people are fully aware of. I’m sure you’ve all read my good friend Paul White (@sql_kiwi)’s post on how the Query Optimizer chooses which type of aggregate function to apply. But let’s take a look at SQL Server Integration Services. SSIS gives us a Aggregate transformation for use in Data Flow Tasks, but it’s described as Blocking. The definitive article on Performance Tuning SSIS uses Sort and Aggregate as examples of Blocking Transformations. I’ve just shown you that Aggregate operations used by the Query Optimizer are not always blocking, but that the SSIS Aggregate component is an example of a blocking transformation. But is it always the case? After all, there are plenty of SSIS Performance Tuning talks out there that describe the value of sorted data in Data Flow Tasks, describing the IsSorted property that can be set through the Advanced Editor of your Source component. And so I set about testing the Aggregate transformation in SSIS, to prove for sure whether providing Sorted data would let the Aggregate transform behave like a Stream Aggregate. (Of course, I knew the answer already, but it helps to be able to demonstrate these things). A query that will produce a million rows in order was in order. Let me rephrase. I used a query which produced the numbers from 1 to 1000000, in a single field, ordered. The IsSorted flag was set on the source output, with the only column as SortKey 1. Performing an Aggregate function over this (counting the number of rows per distinct number) should produce an additional column with 1 in it. If this were being done in T-SQL, the ordered data would allow a Stream Aggregate to be used. In fact, if the Query Optimizer saw that the field had a Unique Index on it, it would be able to skip the Aggregate function completely, and just insert the value 1. This is a shortcut I wouldn’t be expecting from SSIS, but certainly the Stream behaviour would be nice. Unfortunately, it’s not the case. As you can see from the screenshots above, the data is pouring into the Aggregate function, and not being released until all million rows have been seen. It’s not doing a Stream Aggregate at all. This is expected behaviour. (I put that in bold, because I want you to realise this.) An SSIS transformation is a piece of code that runs. It’s a physical operation. When you write T-SQL and ask for an aggregation to be done, it’s a logical operation. The physical operation is either a Stream Aggregate or a Hash Match. In SSIS, you’re telling the system that you want a generic Aggregation, that will have to work with whatever data is passed in. I’m not saying that it wouldn’t be possible to make a sometimes-blocking aggregation component in SSIS. A Custom Component could be created which could detect whether the SortKeys columns of the input matched the Grouping columns of the Aggregation, and either call the blocking code or the non-blocking code as appropriate. One day I’ll make one of those, and publish it on my blog. I’ve done it before with a Script Component, but as Script components are single-use, I was able to handle the data knowing everything about my data flow already. As per my previous post – there are a lot of aspects in which tuning SSIS and tuning execution plans use similar concepts. In both situations, it really helps to have a feel for what’s going on behind the scenes. Considering whether an operation is blocking or not is extremely relevant to performance, and that it’s not always obvious from the surface. In a future post, I’ll show the impact of blocking v non-blocking and synchronous v asynchronous components in SSIS, using some of LobsterPot’s Script Components and Custom Components as examples. When I get that sorted, I’ll make a Stream Aggregate component available for download.

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• The blocking nature of aggregates

  - by Rob Farley

  I wrote a post recently about how query tuning isn’t just about how quickly the query runs – that if you have something (such as SSIS) that is consuming your data (and probably introducing a bottleneck), then it might be more important to have a query which focuses on getting the first bit of data out. You can read that post here.  In particular, we looked at two operators that could be used to ensure that a query returns only Distinct rows. and The Sort operator pulls in all the data, sorts it (discarding duplicates), and then pushes out the remaining rows. The Hash Match operator performs a Hashing function on each row as it comes in, and then looks to see if it’s created a Hash it’s seen before. If not, it pushes the row out. The Sort method is quicker, but has to wait until it’s gathered all the data before it can do the sort, and therefore blocks the data flow. But that was my last post. This one’s a bit different. This post is going to look at how Aggregate functions work, which ties nicely into this month’s T-SQL Tuesday. I’ve frequently explained about the fact that DISTINCT and GROUP BY are essentially the same function, although DISTINCT is the poorer cousin because you have less control over it, and you can’t apply aggregate functions. Just like the operators used for Distinct, there are different flavours of Aggregate operators – coming in blocking and non-blocking varieties. The example I like to use to explain this is a pile of playing cards. If I’m handed a pile of cards and asked to count how many cards there are in each suit, it’s going to help if the cards are already ordered. Suppose I’m playing a game of Bridge, I can easily glance at my hand and count how many there are in each suit, because I keep the pile of cards in order. Moving from left to right, I could tell you I have four Hearts in my hand, even before I’ve got to the end. By telling you that I have four Hearts as soon as I know, I demonstrate the principle of a non-blocking operation. This is known as a Stream Aggregate operation. It requires input which is sorted by whichever columns the grouping is on, and it will release a row as soon as the group changes – when I encounter a Spade, I know I don’t have any more Hearts in my hand. Alternatively, if the pile of cards are not sorted, I won’t know how many Hearts I have until I’ve looked through all the cards. In fact, to count them, I basically need to put them into little piles, and when I’ve finished making all those piles, I can count how many there are in each. Because I don’t know any of the final numbers until I’ve seen all the cards, this is blocking. This performs the aggregate function using a Hash Match. Observant readers will remember this from my Distinct example. You might remember that my earlier Hash Match operation – used for Distinct Flow – wasn’t blocking. But this one is. They’re essentially doing a similar operation, applying a Hash function to some data and seeing if the set of values have been seen before, but before, it needs more information than the mere existence of a new set of values, it needs to consider how many of them there are. A lot is dependent here on whether the data coming out of the source is sorted or not, and this is largely determined by the indexes that are being used. If you look in the Properties of an Index Scan, you’ll be able to see whether the order of the data is required by the plan. A property called Ordered will demonstrate this. In this particular example, the second plan is significantly faster, but is dependent on having ordered data. In fact, if I force a Stream Aggregate on unordered data (which I’m doing by telling it to use a different index), a Sort operation is needed, which makes my plan a lot slower. This is all very straight-forward stuff, and information that most people are fully aware of. I’m sure you’ve all read my good friend Paul White (@sql_kiwi)’s post on how the Query Optimizer chooses which type of aggregate function to apply. But let’s take a look at SQL Server Integration Services. SSIS gives us a Aggregate transformation for use in Data Flow Tasks, but it’s described as Blocking. The definitive article on Performance Tuning SSIS uses Sort and Aggregate as examples of Blocking Transformations. I’ve just shown you that Aggregate operations used by the Query Optimizer are not always blocking, but that the SSIS Aggregate component is an example of a blocking transformation. But is it always the case? After all, there are plenty of SSIS Performance Tuning talks out there that describe the value of sorted data in Data Flow Tasks, describing the IsSorted property that can be set through the Advanced Editor of your Source component. And so I set about testing the Aggregate transformation in SSIS, to prove for sure whether providing Sorted data would let the Aggregate transform behave like a Stream Aggregate. (Of course, I knew the answer already, but it helps to be able to demonstrate these things). A query that will produce a million rows in order was in order. Let me rephrase. I used a query which produced the numbers from 1 to 1000000, in a single field, ordered. The IsSorted flag was set on the source output, with the only column as SortKey 1. Performing an Aggregate function over this (counting the number of rows per distinct number) should produce an additional column with 1 in it. If this were being done in T-SQL, the ordered data would allow a Stream Aggregate to be used. In fact, if the Query Optimizer saw that the field had a Unique Index on it, it would be able to skip the Aggregate function completely, and just insert the value 1. This is a shortcut I wouldn’t be expecting from SSIS, but certainly the Stream behaviour would be nice. Unfortunately, it’s not the case. As you can see from the screenshots above, the data is pouring into the Aggregate function, and not being released until all million rows have been seen. It’s not doing a Stream Aggregate at all. This is expected behaviour. (I put that in bold, because I want you to realise this.) An SSIS transformation is a piece of code that runs. It’s a physical operation. When you write T-SQL and ask for an aggregation to be done, it’s a logical operation. The physical operation is either a Stream Aggregate or a Hash Match. In SSIS, you’re telling the system that you want a generic Aggregation, that will have to work with whatever data is passed in. I’m not saying that it wouldn’t be possible to make a sometimes-blocking aggregation component in SSIS. A Custom Component could be created which could detect whether the SortKeys columns of the input matched the Grouping columns of the Aggregation, and either call the blocking code or the non-blocking code as appropriate. One day I’ll make one of those, and publish it on my blog. I’ve done it before with a Script Component, but as Script components are single-use, I was able to handle the data knowing everything about my data flow already. As per my previous post – there are a lot of aspects in which tuning SSIS and tuning execution plans use similar concepts. In both situations, it really helps to have a feel for what’s going on behind the scenes. Considering whether an operation is blocking or not is extremely relevant to performance, and that it’s not always obvious from the surface. In a future post, I’ll show the impact of blocking v non-blocking and synchronous v asynchronous components in SSIS, using some of LobsterPot’s Script Components and Custom Components as examples. When I get that sorted, I’ll make a Stream Aggregate component available for download.

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• COLUMNS_UPDATED() for audit triggers

  - by Piotr Rodak

  In SQL Server 2005, triggers are pretty much the only option if you want to audit changes to a table. There are many ways you can decide to store the change information. You may decide to store every changed row as a whole, either in a history table or as xml in audit table. The former case requires having a history table with exactly same schema as the audited table, the latter makes data retrieval and management of the table a bit tricky. Both approaches also suffer from the tendency to consume...(read more)

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• Algorithm for spreading labels in a visually appealing and intuitive way

  - by mac

  Short version Is there a design pattern for distributing vehicle labels in a non-overlapping fashion, placing them as close as possible to the vehicle they refer to? If not, is any of the method I suggest viable? How would you implement this yourself? Extended version In the game I'm writing I have a bird-eye vision of my airborne vehicles. I also have next to each of the vehicles a small label with key-data about the vehicle. This is an actual screenshot: Now, since the vehicles could be flying at different altitudes, their icons could overlap. However I would like to never have their labels overlapping (or a label from vehicle 'A' overlap the icon of vehicle 'B'). Currently, I can detect collisions between sprites and I simply push away the offending label in a direction opposite to the otherwise-overlapped sprite. This works in most situations, but when the airspace get crowded, the label can get pushed very far away from its vehicle, even if there was an alternate "smarter" alternative. For example I get: B - label A -----------label C - label where it would be better (= label closer to the vehicle) to get: B - label label - A C - label EDIT: It also has to be considered that beside the overlapping vehicles case, there might be other configurations in which vehicles'labels could overlap (the ASCII-art examples show for example three very close vehicles in which the label of A would overlap the icon of B and C). I have two ideas on how to improve the present situation, but before spending time implementing them, I thought to turn to the community for advice (after all it seems like a "common enough problem" that a design pattern for it could exist). For what it's worth, here's the two ideas I was thinking to: Slot-isation of label space In this scenario I would divide all the screen into "slots" for the labels. Then, each vehicle would always have its label placed in the closest empty one (empty = no other sprites at that location. Spiralling search From the location of the vehicle on the screen, I would try to place the label at increasing angles and then at increasing radiuses, until a non-overlapping location is found. Something down the line of: try 0°, 10px try 10°, 10px try 20°, 10px ... try 350°, 10px try 0°, 20px try 10°, 20px ...

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• Log & monitor mysql databases on servers

  - by user3215

  How MySQL databases logged and monitored on ubuntu servers in real time?. I checked /var/log/mysql.log and found it empty. EDIT 1: The log was not enabled in the mysql configuration file. Now it logs and I could see the logs in the file /var/log/mysql/mysql.log But this could not be sufficient to gather additional information about the database logs. Is there any other way or any popular open source tool?

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• Oracle Tutor: Create Accessible Content for the Disabled Community

  - by emily.chorba(at)oracle.com

  For many reasons--legal, business, and ethical--Oracle recognizes the need for its applications, and our customers' and partners' products built with our tools, to be usable by the disabled community. The following features of Tutor Author and Publisher software facilitate the creation of accessible HTML content for the disabled community.TablesThe following formatting guidelines will ensure that Tutor documents containing tables will be accessible once they are converted to HTML.• Determine whether a table is a "data table" or whether you are using a table simply for formatting. If it's a data table, you must use a heading for each column, and you should format this heading row as "table heading" style and select Table > Heading Rows Repeat.• For non data tables, it is not necessary to include a heading row.GraphicsTo create accessible graphics, add a caption to the graphic. In Microsoft Office 2000 and greater, right-click on the graphic and select Format Picture > Web (tab) > Alternative Text or select the graphic then Format > Picture > Web (tab) Alternative Text. Enter the appropriate information in the dialog box.When a document containing a graphic with alternative text is converted to HTML by Tutor, the HTML document will contain the appropriate accessibility information.Javascript elementsThe tabbed format and other javascript elements in the HTML version of the Tutor documents may not be accessible to all users. A link to an accessible/printable version of the document is available in the upper right corner of all Tutor documents.Repetitive dataIf repetitive data such as the distribution section and the ownership section are causing accessibility issues with your Tutor documents, you can insert a bookmark in the appropriate location of the document, and, when the document is converted to HTML, the bookmark will be converted to an A NAME reference (also known as an internal link). With this reference, you can create a link in Header.txt that can be prepended to each Tutor document that allows the user to bypass repetitive sections. Tutor and Oracle ApplicationsRegarding accessibility, please check Oracle's website on accessibility http://www.oracle.com/accessibility/ to find out what version of E-Business Suite is certified to work with screen readers. Oracle Tutor 11.5.6A and greater works with screen readers such as JAWS.There is no certification between Oracle Tutor and Oracle Applications because there are no related dependencies. It doesn't matter which version of the Oracle Applications you are running. Therefore, it is possible to use Oracle Tutor with earlier versions of Oracle Applications.Oracle Business Process Converter and Oracle ApplicationsOracle Business Process Converter (OBPC) converts Visio, XPDL, and Tutor models to Oracle Business Process Architect and Oracle Business Process Management. The OBPC is one of a collection of plugins to Oracle JDeveloper. Please see the VPAT as the same considerations apply.Learn MoreFor more information about Tutor, visit Oracle.Com or the Tutor Blog. Post your questions at the Tutor Forum. Emily ChorbaPrinciple Product Manager Oracle Tutor & BPM

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• Custom keyboard shortcut to lauch a terminal and run a command in Unity

  - by David Weinraub

  I know this should be the simplest thing, but coming up empty. ;-( I would like to create a keyboard shortcut ctrl-alt-P that opens a terminal window and runs a ping command: ping -c 4 somefixeddomain.com [Useful for quickly checking whether my internet connection is actually working.] I have attempted to do this (in Unity, Ubuntu v11.10) using: Settings > Keyboard > Custom Shortcuts filling in all the obvious stuff, but no luck. All ideas welcome.

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• How do I check user's unlocked achievement and leaderboard scores via GPG plugin

  - by noob

  I need to load user's achievement and their scores from leaderboard in my game. But the Social.LoadScore() and Social.LoadAchievements() both returns a 0 size array in callback. When I checked the implementation in Google Play Gaming's PlayGamePlatform.cs, both the method has this summary - Not implemented yet. Calls the callback with an empty list. So my question is How do I get this data in Unity? Has anyone tried any other method to get the data?

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• Improving Manageability of Virtual Environments

  - by Jeff Victor

  Boot Environments for Solaris 10 Branded Zones Until recently, Solaris 10 Branded Zones on Solaris 11 suffered one notable regression: Live Upgrade did not work. The individual packaging and patching tools work correctly, but the ability to upgrade Solaris while the production workload continued running did not exist. A recent Solaris 11 SRU (Solaris 11.1 SRU 6.4) restored most of that functionality, although with a slightly different concept, different commands, and without all of the feature details. This new method gives you the ability to create and manage multiple boot environments (BEs) for a Solaris 10 Branded Zone, and modify the active or any inactive BE, and to do so while the production workload continues to run. Background In case you are new to Solaris: Solaris includes a set of features that enables you to create a bootable Solaris image, called a Boot Environment (BE). This newly created image can be modified while the original BE is still running your workload(s). There are many benefits, including improved uptime and the ability to reboot into (or downgrade to) an older BE if a newer one has a problem. In Solaris 10 this set of features was named Live Upgrade. Solaris 11 applies the same basic concepts to the new packaging system (IPS) but there isn't a specific name for the feature set. The features are simply part of IPS. Solaris 11 Boot Environments are not discussed in this blog entry. Although a Solaris 10 system can have multiple BEs, until recently a Solaris 10 Branded Zone (BZ) in a Solaris 11 system did not have this ability. This limitation was addressed recently, and that enhancement is the subject of this blog entry. This new implementation uses two concepts. The first is the use of a ZFS clone for each BE. This makes it very easy to create a BE, or many BEs. This is a distinct advantage over the Live Upgrade feature set in Solaris 10, which had a practical limitation of two BEs on a system, when using UFS. The second new concept is a very simple mechanism to indicate the BE that should be booted: a ZFS property. The new ZFS property is named com.oracle.zones.solaris10:activebe (isn't that creative? ). It's important to note that the property is inherited from the original BE's file system to any BEs you create. In other words, all BEs in one zone have the same value for that property. When the (Solaris 11) global zone boots the Solaris 10 BZ, it boots the BE that has the name that is stored in the activebe property. Here is a quick summary of the actions you can use to manage these BEs: To create a BE: Create a ZFS clone of the zone's root dataset To activate a BE: Set the ZFS property of the root dataset to indicate the BE To add a package or patch to an inactive BE: Mount the inactive BE Add packages or patches to it Unmount the inactive BE To list the available BEs: Use the "zfs list" command. To destroy a BE: Use the "zfs destroy" command. Preparation Before you can use the new features, you will need a Solaris 10 BZ on a Solaris 11 system. You can use these three steps - on a real Solaris 11.1 server or in a VirtualBox guest running Solaris 11.1 - to create a Solaris 10 BZ. The Solaris 11.1 environment must be at SRU 6.4 or newer. Create a flash archive on the Solaris 10 system s10# flarcreate -n s10-system /net/zones/archives/s10-system.flar Configure the Solaris 10 BZ on the Solaris 11 system s11# zonecfg -z s10z Use 'create' to begin configuring a new zone. zonecfg:s10z create -t SYSsolaris10 zonecfg:s10z set zonepath=/zones/s10z zonecfg:s10z exit s11# zoneadm list -cv ID NAME STATUS PATH BRAND IP 0 global running / solaris shared - s10z configured /zones/s10z solaris10 excl Install the zone from the flash archive s11# zoneadm -z s10z install -a /net/zones/archives/s10-system.flar -p You can find more information about the migration of Solaris 10 environments to Solaris 10 Branded Zones in the documentation. The rest of this blog entry demonstrates the commands you can use to accomplish the aforementioned actions related to BEs. New features in action Note that the demonstration of the commands occurs in the Solaris 10 BZ, as indicated by the shell prompt "s10z# ". Many of these commands can be performed in the global zone instead, if you prefer. If you perform them in the global zone, you must change the ZFS file system names. Create The only complicated action is the creation of a BE. In the Solaris 10 BZ, create a new "boot environment" - a ZFS clone. You can assign any name to the final portion of the clone's name, as long as it meets the requirements for a ZFS file system name. s10z# zfs snapshot rpool/ROOT/zbe-0@snap s10z# zfs clone -o mountpoint=/ -o canmount=noauto rpool/ROOT/zbe-0@snap rpool/ROOT/newBE cannot mount 'rpool/ROOT/newBE' on '/': directory is not empty filesystem successfully created, but not mounted You can safely ignore that message: we already know that / is not empty! We have merely told ZFS that the default mountpoint for the clone is the root directory. List the available BEs and active BE Because each BE is represented by a clone of the rpool/ROOT dataset, listing the BEs is as simple as listing the clones. s10z# zfs list -r rpool/ROOT NAME USED AVAIL REFER MOUNTPOINT rpool/ROOT 3.55G 42.9G 31K legacy rpool/ROOT/zbe-0 1K 42.9G 3.55G / rpool/ROOT/newBE 3.55G 42.9G 3.55G / The output shows that two BEs exist. Their names are "zbe-0" and "newBE". You can tell Solaris that one particular BE should be used when the zone next boots by using a ZFS property. Its name is com.oracle.zones.solaris10:activebe. The value of that property is the name of the clone that contains the BE that should be booted. s10z# zfs get com.oracle.zones.solaris10:activebe rpool/ROOT NAME PROPERTY VALUE SOURCE rpool/ROOT com.oracle.zones.solaris10:activebe zbe-0 local Change the active BE When you want to change the BE that will be booted next time, you can just change the activebe property on the rpool/ROOT dataset. s10z# zfs get com.oracle.zones.solaris10:activebe rpool/ROOT NAME PROPERTY VALUE SOURCE rpool/ROOT com.oracle.zones.solaris10:activebe zbe-0 local s10z# zfs set com.oracle.zones.solaris10:activebe=newBE rpool/ROOT s10z# zfs get com.oracle.zones.solaris10:activebe rpool/ROOT NAME PROPERTY VALUE SOURCE rpool/ROOT com.oracle.zones.solaris10:activebe newBE local s10z# shutdown -y -g0 -i6 After the zone has rebooted: s10z# zfs get com.oracle.zones.solaris10:activebe rpool/ROOT rpool/ROOT com.oracle.zones.solaris10:activebe newBE local s10z# zfs mount rpool/ROOT/newBE / rpool/export /export rpool/export/home /export/home rpool /rpool Mount the original BE to see that it's still there. s10z# zfs mount -o mountpoint=/mnt rpool/ROOT/zbe-0 s10z# ls /mnt Desktop export platform Documents export.backup.20130607T214951Z proc S10Flar home rpool TT_DB kernel sbin bin lib system boot lost+found tmp cdrom mnt usr dev net var etc opt Patch an inactive BE At this point, you can modify the original BE. If you would prefer to modify the new BE, you can restore the original value to the activebe property and reboot, and then mount the new BE to /mnt (or another empty directory) and modify it. Let's mount the original BE so we can modify it. (The first command is only needed if you haven't already mounted that BE.) s10z# zfs mount -o mountpoint=/mnt rpool/ROOT/zbe-0 s10z# patchadd -R /mnt -M /var/sadm/spool 104945-02 Note that the typical usage will be: Create a BE Mount the new (inactive) BE Use the package and patch tools to update the new BE Unmount the new BE Reboot Delete an inactive BE ZFS clones are children of their parent file systems. In order to destroy the parent, you must first "promote" the child. This reverses the parent-child relationship. (For more information on this, see the documentation.) The original rpool/ROOT file system is the parent of the clones that you create as BEs. In order to destroy an earlier BE that is that parent of other BEs, you must first promote one of the child BEs to be the ZFS parent. Only then can you destroy the original BE. Fortunately, this is easier to do than to explain: s10z# zfs promote rpool/ROOT/newBE s10z# zfs destroy rpool/ROOT/zbe-0 s10z# zfs list -r rpool/ROOT NAME USED AVAIL REFER MOUNTPOINT rpool/ROOT 3.56G 269G 31K legacy rpool/ROOT/newBE 3.56G 269G 3.55G / Documentation This feature is so new, it is not yet described in the Solaris 11 documentation. However, MOS note 1558773.1 offers some details. Conclusion With this new feature, you can add and patch packages to boot environments of a Solaris 10 Branded Zone. This ability improves the manageability of these zones, and makes their use more practical. It also means that you can use the existing P2V tools with earlier Solaris 10 updates, and modify the environments after they become Solaris 10 Branded Zones.

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• Common header file for C++ and JavaScipt

  - by paperjam

  I have an app that runs a C++ server backend and Javascript on the client. I would like to define certain strings once only, for both pieces of code. For example, I might have a CSS class "row-hover" - I want to define this class name in one place only in case I change it later. Is there an easy way to include, or read, some sort of common definitions file into both C++ and JavaScript? Ideally as a compile / preprocessing step but any neat approach good.

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• When to use HTTP status code 404 in an API

  - by Sybiam

  I am working on a project and after arguing with people at work for about more than a hour. I decided to know what people on stack-exchange might say. We're writing an API for a system, there is a query that should return a tree of Organization or a tree of Goals. The tree of Organization is the organization in which the user is present, In other words, this tree should always exists. In the organization, a tree of goal should be always present. (that's where the argument started). In case where the tree doesn't exist, my co-worker decided that it would be right to answer response with status code 200. And then started asking me to fix my code because the application was falling apart when there is no tree. I'll try to spare flames and fury. I suggested to raise a 404 error when there is no tree. It would at least let me know that something is wrong. When using 200, I have to add special check to my response in the success callback to handle errors. I'm expecting to receive an object, but I may actually receive an empty response because nothing is found. It sounds totally fair to mark the response as a 404. And then war started and I got the message that I didn't understand HTTP status code schema. So I'm here and asking what's wrong with 404 in this case? I even got the argument "It found nothing, so it's right to return 200". I believe that it's wrong since the tree should be always present. If we found nothing and we are expecting something, it should be a 404. More info, I forgot to add the urls that are fetched. Organizations /OrgTree/Get Goals /GoalTree/GetByDate?versionDate=... /GoalTree/GetById?versionId=... My mistake, both parameters are required. If any versionDate that can be parsed to a date is provided, it will return the closes revision. If you enter something in the past, it will return the first revision. If by Id with a id that doesn't exists, I suspect it's going to return an empty response with 200. Extra Also, I believe the best answer to the problem is to create default objects when organizations are created, having no tree shouldn't be a valid case and should be seen as an undefined behavior. There is no way an account can be used without both trees. For that reasons, they should be always present. also I got linked this (one similar but I can't find it) http://viswaug.files.wordpress.com/2008/11/http-headers-status1.png

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• Integrating Oracle Hyperion Smart View Data Queries with MS Word and Power Point

  - by Andreea Vaduva

  Untitled Document table { border: thin solid; } Most Smart View users probably appreciate that they can use just one add-in to access data from the different sources they might work with, like Oracle Essbase, Oracle Hyperion Planning, Oracle Hyperion Financial Management and others. But not all of them are aware of the options to integrate data analyses not only in Excel, but also in MS Word or Power Point. While in the past, copying and pasting single numbers or tables from a recent analysis in Excel made the pasted content a static snapshot, copying so called Data Points now creates dynamic, updateable references to the data source. It also provides additional nice features, which can make life easier and less stressful for Smart View users. So, how does this option work: after building an ad-hoc analysis with Smart View as usual in an Excel worksheet, any area including data cells/numbers from the database can be highlighted in order to copy data points - even single data cells only.   TIP It is not necessary to highlight and copy the row or column descriptions   Next from the Smart View ribbon select Copy Data Point. Then transfer to the Word or Power Point document into which the selected content should be copied. Note that in these Office programs you will find a menu item Smart View;from it select the Paste Data Point icon. The copied details from the Excel report will be pasted, but showing #NEED_REFRESH in the data cells instead of the original numbers. =After clicking the Refresh icon on the Smart View menu the data will be retrieved and displayed. (Maybe at that moment a login window pops up and you need to provide your credentials.) It works in the same way if you just copy one single number without any row or column descriptions, for example in order to incorporate it into a continuous text: Before refresh: After refresh: From now on for any subsequent updates of the data shown in your documents you only need to refresh data by clicking the Refresh button on the Smart View menu, without copying and pasting the context or content again. As you might realize, trying out this feature on your own, there won’t be any Point of View shown in the Office document. Also you have seen in the example, where only a single data cell was copied, that there aren’t any member names or row/column descriptions copied, which are usually required in an ad-hoc report in order to exactly define where data comes from or how data is queried from the source. Well, these definitions are not visible, but they are transferred to the Word or Power Point document as well. They are stored in the background for each individual data cell copied and can be made visible by double-clicking the data cell as shown in the following screen shot (but which is taken from another context).   So for each cell/number the complete connection information is stored along with the exact member/cell intersection from the database. And that’s not all: you have the chance now to exchange the members originally selected in the Point of View (POV) in the Excel report. Remember, at that time we had the following selection:   By selecting the Manage POV option from the Smart View meny in Word or Power Point…   … the following POV Manager – Queries window opens:   You can now change your selection for each dimension from the original POV by either double-clicking the dimension member in the lower right box under POV: or by selecting the Member Selector icon on the top right hand side of the window. After confirming your changes you need to refresh your document again. Be aware, that this will update all (!) numbers taken from one and the same original Excel sheet, even if they appear in different locations in your Office document, reflecting your recent changes in the POV. TIP Build your original report already in a way that dimensions you might want to change from within Word or Power Point are placed in the POV. And there is another really nice feature I wouldn’t like to miss mentioning: Using Dynamic Data Points in the way described above, you will never miss or need to search again for your original Excel sheet from which values were taken and copied as data points into an Office document. Because from even only one single data cell Smart View is able to recreate the entire original report content with just a few clicks: Select one of the numbers from within your Word or Power Point document by double-clicking.   Then select the Visualize in Excel option from the Smart View menu. Excel will open and Smart View will rebuild the entire original report, including POV settings, and retrieve all data from the most recent actual state of the database. (It might be necessary to provide your credentials before data is displayed.) However, in order to make this work, an active online connection to your databases on the server is necessary and at least read access to the retrieved data. But apart from this, your newly built Excel report is fully functional for ad-hoc analysis and can be used in the common way for drilling, pivoting and all the other known functions and features. So far about embedding Dynamic Data Points into Office documents and linking them back into Excel worksheets. You can apply this in the described way with ad-hoc analyses directly on Essbase databases or using Hyperion Planning and Hyperion Financial Management ad-hoc web forms. If you are also interested in other new features and smart enhancements in Essbase or Hyperion Planning stay tuned for coming articles or check our training courses and web presentations. You can find general information about offerings for the Essbase and Planning curriculum or other Oracle-Hyperion products here (please make sure to select your country/region at the top of this page) or in the OU Learning paths section , where Planning, Essbase and other Hyperion products can be found under the Fusion Middleware heading (again, please select the right country/region). Or drop me a note directly: [email protected] . About the Author: Bernhard Kinkel started working for Hyperion Solutions as a Presales Consultant and Consultant in 1998 and moved to Hyperion Education Services in 1999. He joined Oracle University in 2007 where he is a Principal Education Consultant. Based on these many years of working with Hyperion products he has detailed product knowledge across several versions. He delivers both classroom and live virtual courses. His areas of expertise are Oracle/Hyperion Essbase, Oracle Hyperion Planning and Hyperion Web Analysis.  

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• Oracle Flashback Technologies - Overview

  - by Sridhar_R-Oracle

  Oracle Flashback Technologies - IntroductionIn his May 29th 2014 blog, my colleague Joe Meeks introduced Oracle Maximum Availability Architecture (MAA) and discussed both planned and unplanned outages. Let’s take a closer look at unplanned outages. These can be caused by physical failures (e.g., server, storage, network, file deletion, physical corruption, site failures) or by logical failures – cases where all components and files are physically available, but data is incorrect or corrupt. These logical failures are usually caused by human errors or application logic errors. This blog series focuses on these logical errors – what causes them and how to address and recover from them using Oracle Database Flashback. In this introductory blog post, I’ll provide an overview of the Oracle Database Flashback technologies and will discuss the features in detail in future blog posts. Let’s get started. We are all human beings (unless a machine is reading this), and making mistakes is a part of what we do…often what we do best!  We “fat finger”, we spill drinks on keyboards, unplug the wrong cables, etc.  In addition, many of us, in our lives as DBAs or developers, must have observed, caused, or corrected one or more of the following unpleasant events: Accidentally updated a table with wrong values !! Performed a batch update that went wrong - due to logical errors in the code !! Dropped a table !! How do DBAs typically recover from these types of errors? First, data needs to be restored and recovered to the point-in-time when the error occurred (incomplete or point-in-time recovery).  Moreover, depending on the type of fault, it’s possible that some services – or even the entire database – would have to be taken down during the recovery process.Apart from error conditions, there are other questions that need to be addressed as part of the investigation. For example, what did the data look like in the morning, prior to the error? What were the various changes to the row(s) between two timestamps? Who performed the transaction and how can it be reversed?  Oracle Database includes built-in Flashback technologies, with features that address these challenges and questions, and enable you to perform faster, easier, and convenient recovery from logical corruptions. HistoryFlashback Query, the first Flashback Technology, was introduced in Oracle 9i. It provides a simple, powerful and completely non-disruptive mechanism for data verification and recovery from logical errors, and enables users to view the state of data at a previous point in time.Flashback Technologies were further enhanced in Oracle 10g, to provide fast, easy recovery at the database, table, row, and even at a transaction level.Oracle Database 11g introduced an innovative method to manage and query long-term historical data with Flashback Data Archive. The 11g release also introduced Flashback Transaction, which provides an easy, one-step operation to back out a transaction. Oracle Database versions 11.2.0.2 and beyond further enhanced the performance of these features. Note that all the features listed here work without requiring any kind of restore operation.In addition, Flashback features are fully supported with the new multi-tenant capabilities introduced with Oracle Database 12c, Flashback Features Oracle Flashback Database enables point-in-time-recovery of the entire database without requiring a traditional restore and recovery operation. It rewinds the entire database to a specified point in time in the past by undoing all the changes that were made since that time.Oracle Flashback Table enables an entire table or a set of tables to be recovered to a point in time in the past.Oracle Flashback Drop enables accidentally dropped tables and all dependent objects to be restored.Oracle Flashback Query enables data to be viewed at a point-in-time in the past. This feature can be used to view and reconstruct data that was lost due to unintentional change(s) or deletion(s). This feature can also be used to build self-service error correction into applications, empowering end-users to undo and correct their errors.Oracle Flashback Version Query offers the ability to query the historical changes to data between two points in time or system change numbers (SCN) Oracle Flashback Transaction Query enables changes to be examined at the transaction level. This capability can be used to diagnose problems, perform analysis, audit transactions, and even revert the transaction by undoing SQLOracle Flashback Transaction is a procedure used to back-out a transaction and its dependent transactions.Flashback technologies eliminate the need for a traditional restore and recovery process to fix logical corruptions or make enquiries. Using these technologies, you can recover from the error in the same amount of time it took to generate the error. All the Flashback features can be accessed either via SQL command line (or) via Enterprise Manager.  Most of the Flashback technologies depend on the available UNDO to retrieve older data. The following table describes the various Flashback technologies: their purpose, dependencies and situations where each individual technology can be used.   Example Syntax Error investigation related:The purpose is to investigate what went wrong and what the values were at certain points in timeFlashback Queries  ( select .. as of SCN | Timestamp )   - Helps to see the value of a row/set of rows at a point in timeFlashback Version Queries  ( select .. versions between SCN | Timestamp and SCN | Timestamp)  - Helps determine how the value evolved between certain SCNs or between timestamps Flashback Transaction Queries (select .. XID=)   - Helps to understand how the transaction caused the changes.Error correction related:The purpose is to fix the error and correct the problems,Flashback Table  (flashback table .. to SCN | Timestamp)  - To rewind the table to a particular timestamp or SCN to reverse unwanted updates Flashback Drop (flashback table ..  to before drop )  - To undrop or undelete a table Flashback Database (flashback database to SCN  | Restore Point )  - This is the rewind button for Oracle databases. You can revert the entire database to a particular point in time. It is a fast way to perform a PITR (point-in-time recovery). Flashback Transaction (DBMS_FLASHBACK.TRANSACTION_BACKOUT(XID..))  - To reverse a transaction and its related transactions Advanced use cases Flashback technology is integrated into Oracle Recovery Manager (RMAN) and Oracle Data Guard. So, apart from the basic use cases mentioned above, the following use cases are addressed using Oracle Flashback. Block Media recovery by RMAN - to perform block level recovery Snapshot Standby - where the standby is temporarily converted to a read/write environment for testing, backup, or migration purposes Re-instate old primary in a Data Guard environment – this avoids the need to restore an old backup and perform a recovery to make it a new standby. Guaranteed Restore Points - to bring back the entire database to an older point-in-time in a guaranteed way. and so on..I hope this introductory overview helps you understand how Flashback features can be used to investigate and recover from logical errors.  As mentioned earlier, I will take a deeper-dive into to some of the critical Flashback features in my upcoming blogs and address common use cases.

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• vi issue in SSH TTYs to Ubuntu 14.04.1 LTS

  - by Steve Campbell

  After upgrading my server to Ubuntu 14.04.1 LTS, I can no longer use the vi editor to edit anything in an SSH terminal (I access the server by launching ssh sessions from Cygwin running on Windows). The empty portions of the vi window fill with garbage. The workaround is to launch an xterm from the server back to my Cygwin/X display. Using vi from within the xterm works fine. Setting my TERM to vt100/vt220/xterm does not help.

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• MythTV lost recordings - "No recordings available" and no recording rules either

  - by nimasmi

  I have a c.6 year old mythtv database. I recently upgraded from Ubuntu 10.04 to 12.04. This brought a MythTV upgrade from 0.24 to 0.25, which went well. Today, all my recordings have disappeared. They still exist in the /var/lib/mythtv/recordings folder, and the 'M' key in the Watch Recordings page says that there are 201 recordings available somewhere, but they will not display. See screenshot: (implicit thanks to whomever upvoted this, giving me sufficient reputation to upload images) Changing the filter does not remedy the fact that there is nothing shown in the lists. My Upcoming Recordings screen says that there are no rules set, but my list of previously recorded shows is still there, and has an entry from as recently as 3am today. mythbackend --printsched gives the following: user@box:~$ mythbackend --printsched 2012-09-22 12:59:20.537008 C mythbackend version: fixes/0.25 [v0.25.2-15-g46cab93] www.mythtv.org 2012-09-22 12:59:20.537043 C Qt version: compile: 4.8.1, runtime: 4.8.1 2012-09-22 12:59:20.537048 N Enabled verbose msgs: general 2012-09-22 12:59:20.537076 N Setting Log Level to LOG_INFO 2012-09-22 12:59:20.537142 I Added logging to the console 2012-09-22 12:59:20.537152 I Added database logging to table logging 2012-09-22 12:59:20.537279 N Setting up SIGHUP handler 2012-09-22 12:59:20.537373 N Using runtime prefix = /usr 2012-09-22 12:59:20.537394 N Using configuration directory = /home/user/.mythtv 2012-09-22 12:59:20.537999 I Assumed character encoding: en_GB.UTF-8 2012-09-22 12:59:20.538599 N Empty LocalHostName. 2012-09-22 12:59:20.538610 I Using localhost value of box 2012-09-22 12:59:20.538792 I Testing network connectivity to '192.168.1.2' 2012-09-22 12:59:20.539420 I Starting process manager 2012-09-22 12:59:20.541412 I Starting IO manager (read) 2012-09-22 12:59:20.541715 I Starting IO manager (write) 2012-09-22 12:59:20.541836 I Starting process signal handler 2012-09-22 12:59:20.684497 N Setting QT default locale to EN_GB 2012-09-22 12:59:20.684694 I Current locale EN_GB 2012-09-22 12:59:20.684813 N Reading locale defaults from /usr/share/mythtv//locales/en_gb.xml 2012-09-22 12:59:20.697623 I New static DB connectionDataDirectCon 2012-09-22 12:59:20.704769 I MythCoreContext: Connecting to backend server: 192.168.1.2:6543 (try 1 of 1) Calculating Schedule from database. Inputs, Card IDs, and Conflict info may be invalid if you have multiple tuners. 2012-09-22 12:59:27.710538 E MythSocket(21dfcd0:14): readStringList: Error, timed out after 7000 ms. 2012-09-22 12:59:27.710592 C Protocol version check failure. The response to MYTH_PROTO_VERSION was empty. This happens when the backend is too busy to respond, or has deadlocked in due to bugs or hardware failure. Things I have tried so far: restart the backend restart the frontend run mythtv-setup and check database passwords and IP addresses change the frontend setting for backend IP from localhost to 192.168.1.2 (the backend/frontend's IP) run optimize_mythdb.pl Other suggestions appreciated.

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• Agile PLM 9.3 Service Pack 2 (SP2 or 9.3.0.2) is released along with AUT 1.6.2.0 and AutoVue 20 for

  - by Shane Goodwin

  Oracle released Agile PLM 9.3 SP2 on June 14 and the Agile installer for AutoVue 20 for Agile PLM on April 30. Also available are the new versions of AUT and Averify - 1.6.3 for both tools. 9.3 SP2 is a combined English and NLS release for use on any version of 9.3.0. SP2 contains many bug fixes and rolls up several Hot Fixes - please review the Readme for all the details. In addition, this release also addresses some scalability issues when working with very large Exports and Reports. When exporting very large BOMs, the export module will now release objects more efficiently to reduce the amount of memory consumed on the Application Server. Adminstrators can also control the maximum row limits for Users verses system processes, like ACS. Several out of the box BOM reports have also been changed to use a new row limit option. The combination of all these changes will provide more stability on the application server for customers managing very large datasets. 9.3 SP2 also adds support for Oracle Database 11gR2 for Windows, Oracle Internet Directory (OID) and Oracle Access Manager (OAM). Please note that currently the Variant Patch is not intended to be released for SP2. Customers running the Variant Patch should remain on 9.3.0.0 or 9.3.0.1. Back in April, we also released the AutoVue 20 for Agile PLM installer. AutoVue 20 has many new features which will help Agile PLM customers. Large multi-page Word documents and 2D CAD documents will open more quickly to the first page or first rendition. Memory usage is less when working with 3D Models. There are many new formats supported for MCAD, 2D Cad, and EDA. AutoVue 20 is immediately available for Windows and Linux platforms. The new software can be found in Edelivery or Metalink / Oracle Support: - AutoVue 20 for Agile PLM is on E-Delivery with part number B58963-01 - Oracle Agile PLM 9.3 Service Pack 2 (9.3.0.2) My Oracle Support Patch ID 9782736 - AVERIFY 1.6.3 My Oracle Support Patch ID 9791892 - AUT 1.6.3 My Oracle Support Patch ID 9791908 - Agile PLM 9.3 SP2 Documentation is available on the OTN Agile Documentation Page

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• Internal Mutation of Persistent Data Structures

  - by Greg Ros

  To clarify, when I mean use the terms persistent and immutable on a data structure, I mean that: The state of the data structure remains unchanged for its lifetime. It always holds the same data, and the same operations always produce the same results. The data structure allows Add, Remove, and similar methods that return new objects of its kind, modified as instructed, that may or may not share some of the data of the original object. However, while a data structure may seem to the user as persistent, it may do other things under the hood. To be sure, all data structures are, internally, at least somewhere, based on mutable storage. If I were to base a persistent vector on an array, and copy it whenever Add is invoked, it would still be persistent, as long as I modify only locally created arrays. However, sometimes, you can greatly increase performance by mutating a data structure under the hood. In more, say, insidious, dangerous, and destructive ways. Ways that might leave the abstraction untouched, not letting the user know anything has changed about the data structure, but being critical in the implementation level. For example, let's say that we have a class called ArrayVector implemented using an array. Whenever you invoke Add, you get a ArrayVector build on top of a newly allocated array that has an additional item. A sequence of such updates will involve n array copies and allocations. Here is an illustration: However, let's say we implement a lazy mechanism that stores all sorts of updates -- such as Add, Set, and others in a queue. In this case, each update requires constant time (adding an item to a queue), and no array allocation is involved. When a user tries to get an item in the array, all the queued modifications are applied under the hood, requiring a single array allocation and copy (since we know exactly what data the final array will hold, and how big it will be). Future get operations will be performed on an empty cache, so they will take a single operation. But in order to implement this, we need to 'switch' or mutate the internal array to the new one, and empty the cache -- a very dangerous action. However, considering that in many circumstances (most updates are going to occur in sequence, after all), this can save a lot of time and memory, it might be worth it -- you will need to ensure exclusive access to the internal state, of course. This isn't a question about the efficacy of such a data structure. It's a more general question. Is it ever acceptable to mutate the internal state of a supposedly persistent or immutable object in destructive and dangerous ways? Does performance justify it? Would you still be able to call it immutable? Oh, and could you implement this sort of laziness without mutating the data structure in the specified fashion?

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• Is ASP.NET MVC completely (and exclusively) based on conventions?

  - by Mike Valeriano

  --TL;DR Is there a "Hello World!" ASP.NET MVC tutorial out there that doesn't rely on conventions and "stock" projects? Is it even possible to take advantage of the technology without reusing the default file structure, and start from a single "hello_world.asp" file or something (like in PHP)? Am I completely mistaken and I should be looking somewhere else, maybe this? I'm interested in the MVC framework, not Web Forms --Background I've played a bit with PHP in the past, just for fun, and now I'm back to it since web development became relevant for me once again. I'm no professional, but I try to gain as much knowledge and control over the technology I'm working with as possible. I'm using Visual Studio 2012 for C# - my "desktop" language of choice - and since I got the Professional Edition from Dreamspark, the Web Development Tools are available, including ASP.NET MVC 4. I won't touch Web Forms, but the MVC Framework got my attention because the MVC pattern is something I can really relate to, since it provides the control I want but... not quite. Learning PHP was easy - and right form the start I could just create a "hello_world.php" file and just do something like this for immediate results: <!-- file: hello_world.php --> <?php> echo "Hello World!"; <?> But I couldn't find a single ASP.NET (MVC) tutorial out there (I'll be sure to buy one of the upcoming MVC 4 books, only a month away or so) that would start like that. They all start with a sample project, building up knowledge from the basics and heavily using conventions as they go along. Which is fine, I suppose, but it's now the best way for me to learn things. Even the "Empty" project template for a new ASP.NET MVC 4 Application in VS2012 is not empty at all: several files and folders are created for you - much like a new C# desktop application project, but with C# I can in fact start from scratch, creating the project structure myself. It is not the case with PHP: I can choose from a plethora of different MVC frameworks I can just create my own framework I can just skip frameworks altogether, and toss random PHP along with my HTML on a single file and make it work I understand the framework needs to establish some rules, but what if I just want to create a single page website with some C# logic behind it? Do I really need to create a whole bloat of files and folders for the sake of convention? Also, please understand that I haven't gotten far on any of those tutorials mainly because of this reason, but, if that's the only way to do it, I'll go for it using one of the books I've mentioned before. This is my first contact with ASP.NET but from the few comparisons I've read, I believe I should stay the hell away from Web Forms. Thank you. (Please forgive the broken English - it is not my primary language.)

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• Tuxedo Load Balancing

  - by Todd Little

  A question I often receive is how does Tuxedo perform load balancing.  This is often asked by customers that see an imbalance in the number of requests handled by servers offering a specific service. First of all let me say that Tuxedo really does load or request optimization instead of load balancing.  What I mean by that is that Tuxedo doesn't attempt to ensure that all servers offering a specific service get the same number of requests, but instead attempts to ensure that requests are processed in the least amount of time.   Simple round robin "load balancing" can be employed to ensure that all servers for a particular service are given the same number of requests.  But the question I ask is, "to what benefit"?  Instead Tuxedo scans the queues (which may or may not correspond to servers based upon SSSQ - Single Server Single Queue or MSSQ - Multiple Server Single Queue) to determine on which queue a request should be placed.  The scan is always performed in the same order and during the scan if a queue is empty the request is immediately placed on that queue and request routing is done.  However, should all the queues be busy, meaning that requests are currently being processed, Tuxedo chooses the queue with the least amount of "work" queued to it where work is the sum of all the requests queued weighted by their "load" value as defined in the UBBCONFIG file.  What this means is that under light loads, only the first few queues (servers) process all the requests as an empty queue is often found before reaching the end of the scan.  Thus the first few servers in the queue handle most of the requests.  While this sounds non-optimal, in fact it capitalizes on the underlying operating systems and hardware behavior to produce the best possible performance.  Round Robin scheduling would spread the requests across all the available servers and thus require all of them to be in memory, and likely not share much in the way of hardware or memory caches.  Tuxedo's system maximizes the various caches and thus optimizes overall performance.  Hopefully this makes sense and now explains why you may see a few servers handling most of the requests.  Under heavy load, meaning enough load to keep all servers that can handle a request busy, you should see a relatively equal number of requests processed.  Next post I'll try and cover how this applies to servers in a clustered (MP) environment because the load balancing there is a little more complicated. Regards,Todd LittleOracle Tuxedo Chief Architect

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• Strengthening code with possibly useless exception handling

  - by rdurand

  Is it a good practice to implement useless exception handling, just in case another part of the code is not coded correctly? Basic example A simple one, so I don't loose everybody :). Let's say I'm writing an app that will display a person's information (name, address, etc.), the data being extracted from a database. Let's say I'm the one coding the UI part, and someone else is writing the DB query code. Now imagine that the specifications of your app say that if the person's information is incomplete (let's say, the name is missing in the database), the person coding the query should handle this by returning "NA" for the missing field. What if the query is poorly coded and doesn't handle this case? What if the guy who wrote the query handles you an incomplete result, and when you try to display the informations, everything crashes, because your code isn't prepared to display empty stuff? This example is very basic. I believe most of you will say "it's not your problem, you're not responsible for this crash". But, it's still your part of the code which is crashing. Another example Let's say now I'm the one writing the query. The specifications don't say the same as above, but that the guy writing the "insert" query should make sure all the fields are complete when adding a person to the database to avoid inserting incomplete information. Should I protect my "select" query to make sure I give the UI guy complete informations? The questions What if the specifications don't explicitly say "this guy is the one in charge of handling this situation"? What if a third person implements another query (similar to the first one, but on another DB) and uses your UI code to display it, but doesn't handle this case in his code? Should I do what's necessary to prevent a possible crash, even if I'm not the one supposed to handle the bad case? I'm not looking for an answer like "(s)he's the one responsible for the crash", as I'm not solving a conflict here, I'd like to know, should I protect my code against situations it's not my responsibility to handle? Here, a simple "if empty do something" would suffice. In general, this question tackles redundant exception handling. I'm asking it because when I work alone on a project, I may code 2-3 times a similar exception handling in successive functions, "just in case" I did something wrong and let a bad case come through.

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• Wine 1.5 %ProgramFiles% error

  - by elclanrs

  I'm trying to install d3dx9 with winetricks on wine 1.5 from ppa and I keep getting an error. I tried: WINEARCH=win32 WINEPREFIX=~/.win32 winecfg sudo WINEARCH=win32 WINEPREFIX=~/.win32 winetricks And still get this error: wine cmd.exe /c echo '%ProgramFiles%' returned empty string If I type wine cmd.exe /c echo '%ProgramFiles%' into the terminal I get C:\Program Files so the path seems correct but not when I run winetricks. I also tried this regedit fix with no luck. Any ideas?

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• How to customize the ubuntu gnome 3 desktop?

  - by Francesco

  This is maybe a stupid question, but how can I choose my own background image on ubuntu gnome 3?? I click on Settings - Background - then I click on the current background preview to change it but I see only the defaults images! No + symbol to add or something. On the 'Pictures' tab there is nothing to select, I get an empty white page? I am running ubuntu gnome 13.04 3.9.6-030906-generic. Thanks!

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• MiniMax function throws null pointer exception

  - by Sven

  I'm working on a school project, I have to build a tic tac toe game with the AI based on the MiniMax algorithm. The two player mode works like it should. I followed the code example on http://ethangunderson.com/blog/minimax-algorithm-in-c/. The only thing is that I get a NullPointer Exception when I run the code. And I can't wrap my finger around it. I placed a comment in the code where the exception is thrown. The recursive call is returning a null pointer, what is very strange because it can't.. When I place a breakpoint on the null return with the help of a if statement, then I see that there ARE still 2 to 3 empty places.. I probably overlooking something. Hope someone can tell me what I'm doing wrong. Here is the MiniMax code (the tic tac toe code is not important): /* * To change this template, choose Tools | Templates * and open the template in the editor. */ package MiniMax; import Game.Block; import Game.Board; import java.util.ArrayList; public class MiniMax { public static Place getBestMove(Board gameBoard, Block.TYPE player) { Place bestPlace = null; ArrayList<Place> emptyPlaces = gameBoard.getEmptyPlaces(); Board newBoard; //loop trough all the empty places for(Place emptyPlace : emptyPlaces) { newBoard = gameBoard.clone(); newBoard.setBlock(emptyPlace.getRow(), emptyPlace.getCell(), player); //no game won and still room to move if(newBoard.getWinner() == Block.TYPE.NONE && newBoard.getEmptyPlaces().size() > 0) { //is an node (has children) Place tempPlace = getBestMove(newBoard, invertPlayer(player)); //ERROR is thrown here! tempPlace is null. emptyPlace.setScore(tempPlace.getScore()); } else { //is an leaf if(newBoard.getWinner() == Block.TYPE.NONE) { emptyPlace.setScore(0); } else if(newBoard.getWinner() == Block.TYPE.X) { emptyPlace.setScore(-1); } else if(newBoard.getWinner() == Block.TYPE.O) { emptyPlace.setScore(1); } //if this move is better then our prev move, take it! if((bestPlace == null) || (player == Block.TYPE.X && emptyPlace.getScore() < bestPlace.getScore()) || (player == Block.TYPE.O && emptyPlace.getScore() > bestPlace.getScore())) { bestPlace = emptyPlace; } } } //This should never be null, but it does.. return bestPlace; } private static Block.TYPE invertPlayer(Block.TYPE player) { if(player == Block.TYPE.X) { return Block.TYPE.O; } return Block.TYPE.X; } }

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• MySQL Input Parameters Add Flexibility to Crosstab Stored Procedures

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