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• Best way to cache apt downloads on a LAN?

  - by Ken Simon

  I have multiple Ubuntu machines at home and a pretty slow internet connection, and sometimes multiple machines need to be updated at once (especially during new Ubuntu releases.) Is there a way where only one of my machines needs to download the packages, and the other machines can use the first machine to get the debs? Does it involve setting up my own local mirror? Or a proxy server? Or can it be made simpler?

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• How to use data mining principles in this project?

  - by Simon

  I'm getting a Data Mining class this semester and we are free for the final project. For a few months I'm working on procedural planets rendering (something like this http://www.youtube.com/watch?v=rL8zDgTlXso). Do you have any idea of which data mining principles I could use to keep working this project ? Maybe I could try to generate interesting terrains from a set of real maps ? Any publications on that subject ? Any other ideas ?

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• High resolution graphical representation of the Earth's surface

  - by Simon

  I've got a library, which I inherited, which presents a zoomable representation of the Earth. It's a Mercator projection and is constructed from triangles, the properties of which are stored in binary files. The surface is built up, for any given view port, by drawing these triangles in an overlapping fashion to produce the image. The definition of each triangle is the lat/long of the vertices. It looks OK at low values of zoom but looks progressively more ragged as the user zooms in. The view ports are primarily referenced though a rectangle of lat/long co-ordinates. I'd like to replace it with a better quality approach. The problem is, I don't know where to begin researching the options as I am not familiar either with the projections needed nor the graphics techniques used to render them. For example, I imagine that I could acquire high resolution images, say Mercator projections although I'm open to anything, break them into tiles and somehow wrap them onto a graphical representation of a sphere. I'm not asking for "how do I", more where should I begin to understand what might be involved and the techniques I will need to learn. I am most grateful for any "Earth rendering 101" pointers folks might have.

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• Searching for an online shop accessible via API

  - by Simon A. Eugster

  I need an online shop with a custom interface (customizing items with Ajax, with a preview included). Writing it myself does not make too much sense (implementing all the payment options etc.), so I would like to use an existing online shop (OpenSource). I would like to build my own UI which, for example, tells the shop to add an item to its cart -- i.e. without using the online shop's native UI. More precisely, it should be an online gallery where the user can directly order an image if he likes it. The final checkout/payment page can be native again. Is there a shop system that supports this? Or is it still faster to write it on my own? Or are there better options?

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• Know your Data Lineage

  - by Simon Elliston Ball

  An academic paper without the footnotes isn’t an academic paper. Journalists wouldn’t base a news article on facts that they can’t verify. So why would anyone publish reports without being able to say where the data has come from and be confident of its quality, in other words, without knowing its lineage. (sometimes referred to as ‘provenance’ or ‘pedigree’) The number and variety of data sources, both traditional and new, increases inexorably. Data comes clean or dirty, processed or raw, unimpeachable or entirely fabricated. On its journey to our report, from its source, the data can travel through a network of interconnected pipes, passing through numerous distinct systems, each managed by different people. At each point along the pipeline, it can be changed, filtered, aggregated and combined. When the data finally emerges, how can we be sure that it is right? How can we be certain that no part of the data collection was based on incorrect assumptions, that key data points haven’t been left out, or that the sources are good? Even when we’re using data science to give us an approximate or probable answer, we cannot have any confidence in the results without confidence in the data from which it came. You need to know what has been done to your data, where it came from, and who is responsible for each stage of the analysis. This information represents your data lineage; it is your stack-trace. If you’re an analyst, suspicious of a number, it tells you why the number is there and how it got there. If you’re a developer, working on a pipeline, it provides the context you need to track down the bug. If you’re a manager, or an auditor, it lets you know the right things are being done. Lineage tracking is part of good data governance. Most audit and lineage systems require you to buy into their whole structure. If you are using Hadoop for your data storage and processing, then tools like Falcon allow you to track lineage, as long as you are using Falcon to write and run the pipeline. It can mean learning a new way of running your jobs (or using some sort of proxy), and even a distinct way of writing your queries. Other Hadoop tools provide a lot of operational and audit information, spread throughout the many logs produced by Hive, Sqoop, MapReduce and all the various moving parts that make up the eco-system. To get a full picture of what’s going on in your Hadoop system you need to capture both Falcon lineage and the data-exhaust of other tools that Falcon can’t orchestrate. However, the problem is bigger even that that. Often, Hadoop is just one piece in a larger processing workflow. The next step of the challenge is how you bind together the lineage metadata describing what happened before and after Hadoop, where ‘after’ could be  a data analysis environment like R, an application, or even directly into an end-user tool such as Tableau or Excel. One possibility is to push as much as you can of your key analytics into Hadoop, but would you give up the power, and familiarity of your existing tools in return for a reliable way of tracking lineage? Lineage and auditing should work consistently, automatically and quietly, allowing users to access their data with any tool they require to use. The real solution, therefore, is to create a consistent method by which to bring lineage data from these data various disparate sources into the data analysis platform that you use, rather than being forced to use the tool that manages the pipeline for the lineage and a different tool for the data analysis. The key is to keep your logs, keep your audit data, from every source, bring them together and use the data analysis tools to trace the paths from raw data to the answer that data analysis provides.

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• Using Definition of Done to Drive Agile Maturity

  - by Dylan Smith

  I’ve been an Agile Coach at a lot of different clients over the years, and I want to share an approach I use to help them adopt and mature over time. It’s important to realize that “Agile” is not a black/white yes/no thing. Teams can be varying degrees of agile. I think of this as their agile maturity level. When I coach teams I want them to start out being a little agile, and get more agile as they mature. The approach I teach them is to use the definition of done as a technique to continuously improve their agile maturity over time. We’re probably all familiar with the concept of “Done Done” that represents what *actually* being done a feature means. Not just when a developer says he’s done right after he writes that last line of code that makes the feature kind-of work. Done Done means the coding is done, it’s been tested, installers and deployment packages have been created, user manuals have been updated, architecture docs have been updated, etc. To enable teams to internalize the concept of “Done Done”, they usually get together and come up with their Definition of Done (DoD) that defines all the activities that need to be completed before a feature is considered Done Done. The Done Done technique typically is applied only to features (aka User Stories). What I do is extend this to apply to several concepts such as User Stories, Sprints, Releases (and sometimes Check-Ins). During project kick-off I’ll usually sit down with the team and go through an exercise of creating DoD’s for each of these concepts (Stories/Sprints/Releases). We’ll usually start by just brainstorming a bunch of activities that could end up in these various DoD’s. Here’s some examples: Code Reviews StyleCop FxCop User Manuals Updated Architecture Docs Updated Tested by QA Tested by UAT Installers Created Support Knowledge Base Updated Deployment Instructions (for Ops) written Automated Unit Tests Run Automated Integration Tests Run Then we start by arranging these activities into the place they occur today (e.g. Do you do UAT testing only once per release? every sprint? every feature?). If the team was previously Waterfall most of these activities probably end up in the Release DoD. An extremely mature agile team would probably have most of these activities in the DoD for the User Stories (because an extremely mature agile team will probably do continuous deployment and release every story). So what we need to do as a team, is work to move these activities from their current home (Release DoD) down into the Sprint DoD and eventually into the User Story DoD (and maybe into the lower-level Check-In DoD if we decide to use that). We don’t have to move them all down to User Story immediately, but as a team we figure out what we think we’re capable of moving down to the Sprint cycle, and Story cycle immediately, and that becomes our starting DoD’s. Over time the team makes an effort to continue moving activities down from Release->Sprint->Story as they become more agile and more mature. I try to encourage them to envision a world in which they deploy to production as each User Story is completed. They would need to be updating User Manuals, creating installers, doing UAT testing (typical Release cycle activities) on every single User Story. They may never actually reach that point, but they should envision that, and strive to keep driving the activities down closer to the User Story cycle s they mature. This is a great technique to give a team an easy-to-follow roadmap to mature their agile practices over time. Sure there’s other aspects to maturity outside of this, but it’s a great technique, that’s easy to visualize, to drive agility into the team. Just keep moving those activities (aka “gates”) down the board from Release->Sprint->Story. I’ll try to give an example of what a recent client of mine had for their DoD’s (this is from memory, so probably not 100% accurate): Release Create/Update deployment Instructions For Ops Instructional Videos Updated Run manual regression test suite UAT Testing In this case that meant deploying to an environment shared across the enterprise that mirrored production and asking other business groups to test their own apps to ensure we didn’t break anything outside our system Sprint Deploy to UAT Environment But not necessarily actually request UAT testing occur User Guides updated Sprint Features Video Created In this case we decided to create a video each sprint showing off the progress (video version of Sprint Demo) User Story Manual Test scripts developed and run Tested by BA Deployed in shared QA environment Using automated deployment process Peer Code Review Code Check-In Compiled (warning-free) Passes StyleCop Passes FxCop Create installer packages Run Automated Tests Run Automated Integration Tests PS – One of my clients had a great question when we went through this activity. They said that if a Sprint is by definition done when the end-date rolls around (time-boxed), isn’t a DoD on a sprint meaningless – it’s done on the end-date regardless of whether those other activities are complete or not? My answer is that while that statement is true – the sprint is done regardless when the end date rolls around – if the DoD activities haven’t been completed I would consider the Sprint a failure (similar to not completing what was committed/planned – failure may be too strong a word but you get the idea). In the Retrospective that will become an agenda item to discuss and understand why we weren’t able to complete the activities we agreed would need to be completed each Sprint.

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

  - by Simon Cooper

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

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• A very useful custom component

  - by Kevin Smith

  Whenever I am debugging a problem in WebCenter Content (WCC) I often find it useful to see the contents of the internal data binder used by WCC when executing a service. I want to know the value of all parameters passed in by the caller, either a user in the web GUI or from an application calling the service via RIDC or web services. I also want to the know the value of binder variables calculated by WCC as it processes a service. What defaults has it applied based on configuration settings or profile rules? What values has it derived based on the user input? To help with this I created a  component that uses a java filter to dump out the contents of the internal data binder to the WCC trace file. It dumps the binder contents using the toString() method. You can register this filter code using many different filter hooks to see how the binder is updated as WCC processes the service. By default, it uses the validateStandard filter hook which is useful during a CHECKIN service. It uses the system trace section, so make sure that trace section is enabled before looking for the output from this component. Here is some sample output>system/6    10.09 09:57:40.648    IdcServer-1    filter: postParseDataForServiceRequest, binder start -- system/6    10.09 09:57:40.698    IdcServer-1    *** LocalData *** system/6    10.09 09:57:40.698    IdcServer-1    (10 keys + 0 defaults) system/6    10.09 09:57:40.698    IdcServer-1    ClientEncoding=UTF-8 system/6    10.09 09:57:40.698    IdcServer-1    IdcService=CHECKIN_UNIVERSAL system/6    10.09 09:57:40.698    IdcServer-1    NoHttpHeaders=0 system/6    10.09 09:57:40.698    IdcServer-1    UserDateFormat=iso8601 system/6    10.09 09:57:40.698    IdcServer-1    UserTimeZone=UTC system/6    10.09 09:57:40.698    IdcServer-1    dDocTitle=Check in from RIDC using Framework Folder system/6    10.09 09:57:40.698    IdcServer-1    dDocType=Document system/6    10.09 09:57:40.698    IdcServer-1    dSecurityGroup=Public system/6    10.09 09:57:40.698    IdcServer-1    parentFolderPath=/folder1/folder2 system/6    10.09 09:57:40.698    IdcServer-1    primaryFile=testfile5.bin     system/6    10.09 09:57:40.698    IdcServer-1    ***  RESULT SETS  ***>system/6    10.09 09:57:40.698    IdcServer-1    binder end -------------------------------------------- See the readme included in the component for more details. You can download the component from here.

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• today's multi-device world for web development

  - by paul smith

  With the huge explosion of mobile devices and addition of HTML5/CSS3, there seems to be a shift towards "responsive" designs (i.e., adapting to smaller screen sizes) which seems to be achieved using CSS3's Media Queries. My question is, given the current need of adapting to both desktop and mobile, is it common practice to actually organize two versions of your website (one for desktop and one for mobile)? Or is there just one version with different css files for targeting different devices and screens? Handling just cross-browser (ie6, ff3, opera9, etc...) HTML4/5, CSS2/3 was already hard enough, but now we're expected to handle cross-device (phone, tablet, etc...) as well, so my assumption is company's would create a separate project for mobile and redirect based on the user agent, but this is just a guess.

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• Sidebar for Navigation in Website

  - by Johnson Smith

  I want to have a sidebar in my website with navigation in it. I will use script like phpBB etc. but I want sidebar to be displayed on every page. So I am thinking about making a Sidebar in HTML and then using frame tag for displaying other pages/scripts. But as Frames are getting obsolute, Is there any other method to display a sidebar in everypage without using frames and without adding html coding on every page?

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• Linux,Apache,NetBeans,PHP == Windows,IIS/Cassini,Visual Studio,ASP.Net

  - by Neil Smith

  I've worked out how to get my linux based Netbeans PHP development machine to behave much like what happens when you create a new ASP.Net project in Visual Studio. Firstly create multiple PHP project in Netbeans,say for example mysite1 and mysite2. Next edit the apache2/sites-enabled/000-default file and add two virtualhost sections as below <VirtualHost 127.0.1.1> ServerName mysite1.localhost DocumentRoot /var/www/mysite1/ </VirtualHost> <VirtualHost 127.0.2.1> ServerName mysite2.localhost DocumentRoot /var/www/mysite2/ </VirtualHost> For each site you add, pick a different ip address similar to the above where I use the third octet to increment, next edit the etc/hosts file and add the following two lines 127.0.1.1 mysite1.localhost 127.0.2.1 mysite2.localhost Then in Netbeans, go to File->Project Properties click on 'Run Configuration' and set 'Project Url' to http://mysite1.localhost for the first project and http://mysite2.localhost for the second project. That will give you a PHP development box which develops multiple PHP projects similar to how a Visual Studio Windows based box handles multiple ASP.Net sites. Hope this helps someone :)

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• Framework Folders and Duplicate File Names

  - by Kevin Smith

  I have been working with Framework folders a little bit in the past few days and found one unexpected behavior that is different from Contribution Folders (Folders_g). If you try and check a file into a Framework Folder that already exists in the folder it will allow it and rename the file for you. In Folders_g this would have generated an error and prevented you from checking in the file. A quick check of the Framework Folder configuration settings in the Application Administrator’s Guide for Content Server does not show a configuration parameter to control this. I'm still thinking about this and not sure if I like this new behavior or not. I guess from a user perspective this more closely aligns Framework Folders to how Windows handle duplicate file names, but if you are migrating from Folders_g and expect a duplicate file name to be rejected, this might cause you some problems.

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• SEO on an existing platform

  - by Simon

  I'm given the task to increase user visits and conversions on for a recruitment website. Conversions would be interested job seekers submitting their CV. The manager would first like to increase the organic search results and optimize the website before starting with targeted campaigns. The problem is, they are using a proprietary recruitment software platform which I can barely add changes to. For example, the url's all look like dynamic url's without any semantic meaning and the markup is almost completely build automatically by that platform. I'm also confident that the lack of submitted CV's is due to a bad user experience of the website (no incentives or clear CTA to register) Besides optimizing the static texts and page titles, is there anything I can do? Thanks

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• Collision detection with non-rectangular images

  - by Adam Smith

  I'm creating a game and I need to detect collisions between a character and some parts of the environment. Since my character's frames are taken from a sprite sheet with a transparent background, I'm wondering how I should go about detecting collisions between a wall and my character only if the colliding parts are non-transparent in both images. I thought about checking only if part of the rectangle the character is in touches the rectangle a tile is in and comparing the alpha channels, but then I have another choice to make... Either I test every single pixel against every single pixel in the other image and if one is true, I detect a collision. That would be terribly ineficient. The other option would be to keep a x,y position of the leftmost, rightmost, etc. non-transparent pixel of each image and compare those instead. The problem with this one might be that, for instance, the character's hand could be above a tile (so it would be in a transparent zone of the tile) but a pixel that is not the rightmost could touch part of the tile without being detected. Another problem would be that in different frames, the rightmost, leftmost, etc. pixels might not be at the same position. Should I not bother with that and just check the collisions on the rectangles? It would be simpler, but I'm afraid people.will feel that there are collisions sometimes that shouldn't happen.

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• Subterranean IL: Exception handling 2

  - by Simon Cooper

  Control flow in and around exception handlers is tightly controlled, due to the various ways the handler blocks can be executed. To start off with, I'll describe what SEH does when an exception is thrown. Handling exceptions When an exception is thrown, the CLR stops program execution at the throw statement and searches up the call stack looking for an appropriate handler; catch clauses are analyzed, and filter blocks are executed (I'll be looking at filter blocks in a later post). Then, when an appropriate catch or filter handler is found, the stack is unwound to that handler, executing successive finally and fault handlers in their own stack contexts along the way, and program execution continues at the start of the catch handler. Because catch, fault, finally and filter blocks can be executed essentially out of the blue by the SEH mechanism, without any reference to preceding instructions, you can't use arbitary branches in and out of exception handler blocks. Instead, you need to use specific instructions for control flow out of handler blocks: leave, endfinally/endfault, and endfilter. Exception handler control flow try blocks You cannot branch into or out of a try block or its handler using normal control flow instructions. The only way of entering a try block is by either falling through from preceding instructions, or by branching to the first instruction in the block. Once you are inside a try block, you can only leave it by throwing an exception or using the leave <label> instruction to jump to somewhere outside the block and its handler. The leave instructions signals the CLR to execute any finally handlers around the block. Most importantly, you cannot fall out of the block, and you cannot use a ret to return from the containing method (unlike in C#); you have to use leave to branch to a ret elsewhere in the method. As a side effect, leave empties the stack. catch blocks The only way of entering a catch block is if it is run by the SEH. At the start of the block execution, the thrown exception will be the only thing on the stack. The only way of leaving a catch block is to use throw, rethrow, or leave, in a similar way to try blocks. However, one thing you can do is use a leave to branch back to an arbitary place in the handler's try block! In other words, you can do this: .try { // ... newobj instance void [mscorlib]System.Exception::.ctor() throw MidTry: // ... leave.s RestOfMethod } catch [mscorlib]System.Exception { // ... leave.s MidTry } RestOfMethod: // ... As far as I know, this mechanism is not exposed in C# or VB. finally/fault blocks The only way of entering a finally or fault block is via the SEH, either as the result of a leave instruction in the corresponding try block, or as part of handling an exception. The only way to leave a finally or fault block is to use endfinally or endfault (both compile to the same binary representation), which continues execution after the finally/fault block, or, if the block was executed as part of handling an exception, signals that the SEH can continue walking the stack. filter blocks I'll be covering filters in a separate blog posts. They're quite different to the others, and have their own special semantics. Phew! Complicated stuff, but it's important to know if you're writing or outputting exception handlers in IL. Dealing with the C# compiler is probably best saved for the next post.

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• Easter eggs as IP protection in software

  - by Simon

  I work in embedded software, and for some reason, management wants to hide an Easter egg as means of IP protection. They call it a watermark, and since our software interact with the video preview feed (the image displayed on a screen before you take a photo), they want me to implement a trigger which will react to some unusual video input (a video konami code like dark - bright - dark - bright - whatever). When this trigger fires, something strange happens (which is outside of the normal behavior of the software). The goal is to check whether our software is included in a device. Does it sound like a good idea? I have many argument against this move: What if the konami code is too sensitive and user triggers it? Does this kind of watermark have any legal value? What if this "feature" is discovered by the client? The performance penalty should be very small, since the soft run on small devices. I am the one developping this trigger. If things go wrong, what is my responsibility? What is your opinion about this method? I can't find a link, but I remember seeing an answer on this site suggesting that putting Easter eggs for protection purpose was a good idea. Has anyone tried it with good results?

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• Weird system freeze. Nothing works keyboard/mouse/reset button - Ubuntu 12.04 64bits [closed]

  - by Simon

  I have fresh PC: i5 3570K with Intel 4000 onboard ASrock Z77 Extreme4-m 8GG RAM - Adata 1333Mhz... 1TB Seagate drive 7200rpm I've also fresh systems - Ubuntu/Win7 and today there was something strange. Ubuntu twice just freezed. Everything stopped, even keyboard and mouse wasn't responding. Even RESET button didn't work. Right now memtest is running, but I'd like to know, where else can i look for cause. Can it be software fault if even reset isn't working? Only long reset pressing rebooted PC... I'm a bit confused. Or should I test components - CPU, motherboard, disk. Which logs in Ubuntu should I check to diagnose cause? EHm I had few adventures with this PC already. Shipped motherboard was broken (ASrock Z68 Extreme3) and had old bios, so I had to contact with reseller, replace it and at the end decided on Z77, but everything took 3 weeks, so I have bad feelings... Edit: Both freezes were during editing something in gedit (it can be coincidence) and after few updates today - when memtest is end I'll check what was updated

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• E-mail solution recommedation?

  - by Brownsithily Smith

  Do you currently use email marketing as part of your online marketing strategy to new prospects,customers & clients? If yes: What is your single biggest problem/challenge with email marketing? What is your single most important question about email marketing? If no: What is stopping you? Do you plan to go on your email marketing for online business & ecommerce? Any experience or recommendation?

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• Learning node.js

  - by john smith

  I am not sure if this is the right place to ask but, I thought this was the most suitable. I recently graduated from university. Learned the full php stack; basically all the LAMP stuff, obviously without counting all the other subjects. Not even got my degree and this whole node.js booming out of nowhere. You can imagine how one can feel about this, the story is always the same: you never end learning, and studying. So I recently got my hands on node.js; reading books, tutorials, and everything imaginable on the internet. The problem is one and simple: this is nowhere near to having a teacher standing near you helping you understanding and solving your problems, especially when all you can do is post your doubts on a website and patiently wait for replies. It's not that it isn't good, it's just much slower than what I just expressed above. So, in short words: is there a place where one can find someone willing to teach you about such contents? This would obviously done via remote means, like skype and such. Can anyone here point me into the right direction? Or just downvote me for being in the wrong website? Thanks in advance.

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• finding houses within a radius

  - by paul smith

  During an interview I was asked given the following: A real estate application that lists all houses that are currently on the market (i.e., for sale) within a given distance (say for example the user wants to find all houses within 20 miles), how would you design your application (both data structure and alogirithm) to build this type of service? Any ideas? How would you implement it? I told him I didn't know becaue I've never done any geo-related stuff before.

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• Meet Windows Azure Sweden &amp; SWAG Sommeravslutning

  - by Alan Smith

  The Meet Windows Azure event last week saw some great announcements about the current and future developments on the Windows Azure platform. Microsoft Sweden will be hosting an event at their offices that will run through these releases and demo some of the new technologies. It will be a great chance to see the new capabilities in action, and chat to Microsoft Evangelists, MVPs and other developers about the future of the platform. This will also be the last Sweden Windows Azure Group (SWAG) meeting before the summer break, so there will be food, drinks, and the chance of some “SWAG”. We will be back in force after the summer, and have a number of great events planned for the rest of the year. We will have a big announcement to make regarding one of these, so be there and get the chance to register! Registration is here.

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• IOS Variable vs Property

  - by William Smith

  Just started diving into Objective-C and IOS development and was wondering when and the correct location I should be declaring variables/properties. The main piece of code i need explaining is below: Why and when should i be declaring variables inside the interface statement and why do they have the same variable with _ and then the same one as a property. And then in the implementation they do @synthesize tableView = _tableView (I understand what synthesize does) Thanks :-) @interface ViewController : UIViewController <UITableViewDataSource, UITableViewDelegate> { UITableView *_tableView; UIActivityIndicatorView *_activityIndicatorView; NSArray *_movies; } @property (nonatomic, retain) UITableView *tableView; @property (nonatomic, retain) UIActivityIndicatorView *activityIndicatorView; @property (nonatomic, retain) NSArray *movies;

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• in memory datastore in haskell

  - by Simon

  I want to implement an in memory datastore for a web service in Haskell. I want to run transactions in the stm monad. When I google hash table steam Haskell I only get this: Data. BTree. HashTable. STM. The module name and complexities suggest that this is implemented as a tree. I would think that an array would be more efficient for mutable hash tables. Is there a reason to avoid using an array for an STM hashtable? Do I gain anything with this stem hash table or should I just use a steam ref to an IntMap?

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• Developing Schema Compare for Oracle (Part 4): Script Configuration

  - by Simon Cooper

  If you've had a chance to play around with the Schema Compare for Oracle beta, you may have come across this screen in the synchronization wizard: This screen is one of the few screens that, along with the project configuration form, doesn't come from SQL Compare. This screen was designed to solve a couple of issues that, although aren't specific to Oracle, are much more of a problem than on SQL Server: Datatype conversions and NOT NULL columns. 1. Datatype conversions SQL Server is generally quite forgiving when it comes to datatype conversions using ALTER TABLE. For example, you can convert from a VARCHAR to INT using ALTER TABLE as long as all the character values are parsable as integers. Oracle, on the other hand, only allows ALTER TABLE conversions that don't change the internal data format. Essentially, every change that requires an actual datatype conversion has to be done using a rebuild with a conversion function. That's OK, as we can simply hard-code the various conversion functions for the valid datatype conversions and insert those into the rebuild SELECT list. However, as there always is with Oracle, there's a catch. Have a look at the NUMTODSINTERVAL function. As well as specifying the value (or column) to convert, you have to specify an interval_unit, which tells oracle how to interpret the input number. We can't hardcode a default for this parameter, as it is entirely dependent on the user's data context! So, in order to convert NUMBER to INTERVAL DAY TO SECOND/INTERVAL YEAR TO MONTH, we need to have feedback from the user as to what to put in this parameter while we're generating the sync script - this requires a new step in the engine action/script generation to insert these values into the script, as well as new UI to allow the user to specify these values in a sensible fashion. In implementing the engine and UI infrastructure to allow this it made much more sense to implement it for any rebuild datatype conversion, not just NUMBER to INTERVALs. For conversions which we can do, we pre-fill the 'value' box with the appropriate function from the documentation. The user can also type in arbitary SQL expressions, which allows the user to specify optional format parameters for the relevant conversion functions, or indeed call their own functions to convert between values that don't have a built-in conversion defined. As the value gets inserted as-is into the rebuild SELECT list, any expression that is valid in that context can be specified as the conversion value. 2. NOT NULL columns Another problem that is solved by the new step in the sync wizard is adding a NOT NULL column to a table. If the table contains data (as most database tables do), you can't just add a NOT NULL column, as Oracle doesn't know what value to put in the new column for existing rows - the DDL statement will fail. There are actually 3 separate scenarios for this problem that have separate solutions within the engine: Adding a NOT NULL column to a table without a rebuild Here, the workaround is to add a column default with an appropriate value to the column you're adding: ALTER TABLE tbl1 ADD newcol NUMBER DEFAULT <value> NOT NULL; Note, however, there is something to bear in mind about this solution; once specified on a column, a default cannot be removed. To 'remove' a default from a column you change it to have a default of NULL, hence there's code in the engine to treat a NULL default the same as no default at all. Adding a NOT NULL column to a table, where a separate change forced a table rebuild Fortunately, in this case, a column default is not required - we can simply insert the default value into the rebuild SELECT clause. Changing an existing NULL to a NOT NULL column To implement this, we run an UPDATE command before the ALTER TABLE to change all the NULLs in the column to the required default value. For all three, we need some way of allowing the user to specify a default value to use instead of NULL; as this is essentially the same problem as datatype conversion (inserting values into the sync script), we can re-use the UI and engine implementation of datatype conversion values. We also provide the option to alter the new column to allow NULLs, or to ignore the problem completely. Note that there is the same (long-running) problem in SQL Compare, but it is much more of an issue in Oracle as you cannot easily roll back executed DDL statements if the script fails at some point during execution. Furthermore, the engine of SQL Compare is far less conducive to inserting user-supplied values into the generated script. As we're writing the Schema Compare engine from scratch, we used what we learnt from the SQL Compare engine and designed it to be far more modular, which makes inserting procedures like this much easier.

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• Getting graduates up to speed?

  - by Simon

  This question got me thinking about how comapnies deal with newly-hired graduated. Do experienced programmers expect CS graduates to write clean code (by clean I mean code easily understandable by others — maybe that is too much to expect?) Or do significant portion of graduates at your place (if any) just end up testing and fixing small bugs on existing applications? And, even if they do bug fixes, do you end up spending double the amount of time just checking they did not end up breaking anything and creating new bugs? How do you deal with such scenarios when pair programming and code reviews are not available options (for reasons such as personal deadlines), and also what techniques did you find to get fresh graduate up to speed? Some suggestions would be great.

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