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  • Hybrid IT or Cloud Initiative – a Perfect Enterprise Architecture Maturation Opportunity

    - by Ted McLaughlan
    Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} All too often in the growth and maturation of Enterprise Architecture initiatives, the effort stalls or is delayed due to lack of “applied traction”. By this, I mean the EA activities - whether targeted towards compliance, risk mitigation or value opportunity propositions – may not be attached to measurable, active, visible projects that could advance and prove the value of EA. EA doesn’t work by itself, in a vacuum, without collaborative engagement and a means of proving usefulness. A critical vehicle to this proof is successful orchestration and use of assets and investment resources to meet a high-profile business objective – i.e. a successful project. More and more organizations are now exploring and considering some degree of IT outsourcing, buying and using external services and solutions to deliver their IT and business requirements – vs. building and operating in-house, in their own data centers. The rapid growth and success of “Cloud” services makes some decisions easier and some IT projects more successful, while dramatically lowering IT risks and enabling rapid growth. This is particularly true for “Software as a Service” (SaaS) applications, which essentially are complete web applications hosted and delivered over the Internet. Whether SaaS solutions – or any kind of cloud solution - are actually, ultimately the most cost-effective approach truly depends on the organization’s business and IT investment strategy. This leads us to Enterprise Architecture, the connectivity between business strategy and investment objectives, and the capabilities purchased or created to meet them. If an EA framework already exists, the approach to selecting a cloud-based solution and integrating it with internal IT systems (i.e. a “Hybrid IT” solution) is well-served by leveraging EA methods. If an EA framework doesn’t exist, or is simply not mature enough to address complex, integrated IT objectives – a hybrid IT/cloud initiative is the perfect project to advance and prove the value of EA. Why is this? For starters, the success of any complex IT integration project - spanning multiple systems, contracts and organizations, public and private – depends on active collaboration and coordination among the project stakeholders. For a hybrid IT initiative, inclusive of one or more cloud services providers, the IT services, business workflow and data governance challenges alone can be extremely complex, requiring many diverse layers of organizational expertise and authority. Establishing subject matter expertise, authorities and strategic guidance across all the disciplines involved in a hybrid-IT or hybrid-cloud system requires top-level, comprehensive experience and collaborative leadership. Tools and practices reflecting industry expertise and EA alignment can also be very helpful – such as Oracle’s “Cloud Candidate Selection Tool”. Using tools like this, and facilitating this critical collaboration by leading, organizing and coordinating the input and expertise into a shared, referenceable, reusable set of authority models and practices – this is where EA shines, and where Enterprise Architects can be most valuable. The “enterprise”, in this case, becomes something greater than the core organization – it includes internal systems, public cloud services, 3rd-party IT platforms and datacenters, distributed users and devices; a whole greater than the sum of its parts. Through facilitated project collaboration, leading to identification or creation of solid governance models and processes, a durable and useful Enterprise Architecture framework will usually emerge by itself, if not actually identified and managed as such. The transition from planning collaboration to actual coordination, where the program plan, schedule and resources become synchronized and aligned to other investments in the organization portfolio, is where EA methods and artifacts appear and become most useful. The actual scope and use of these artifacts, in the context of this project, can then set the stage for the most desirable, helpful and pragmatic form of the now-maturing EA framework and community of practice. Considering or starting a hybrid-IT or hybrid-cloud initiative? Running into some complex relationship challenges? This is the perfect time to take advantage of your new, growing or possibly latent Enterprise Architecture practice.

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  • How can Java be improved so that it no longer needs to perform type erasure? [closed]

    - by user63904
    The official Java tutorial on generics explains type erasure and why it was added to the compiler: When a generic type is instantiated, the compiler translates those types by a technique called type erasure — a process where the compiler removes all information related to type parameters and type arguments within a class or method. Type erasure enables Java applications that use generics to maintain binary compatibility with Java libraries and applications that were created before generics. This most likely was a pragmatic approach, or perhaps the least painful one. However, now that generics is widely supported across the industry, what can be done in order for us to not need type erasure? Is it feasible with out needing to break backwards compatibility, or if it is feasible, is it practical? Has the last the last statement in the quote above become self referential? That is: "type erasure enables Java applications that use generics to maintain binary compatibility with Java libraries and applications that were created with Java versions that perform type erasure."

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  • Azure

    - by Grant Fritchey
    I've been tasked to learn SQL Azure, as well as test all the Red Gate products on it. My one, BIG, fear has been that I'll receive some mongo bill in the mail because I've exceeded the MSDN testing limit. I know people that have had that problem. I've been trying to keep an eye on my usage, but, let's face it, it's not something I think about every day. But now I don't have to. Red Gate has been working with Azure, long before I showed up. They already released a little piece of software that I just found out about, it's called CloudTally. It gathers your usage and sends you a daily email so you can know if you're starting to approach that limit. Check it out, it's free.

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  • Whats a good structure to save and retrieve locations of images?

    - by Goot
    I got a java-ee application, where I collect informations about movies. Im my backend I provide data like the name, description, genre and a random uuid. I also got lots of related files, which are stored on a file server. Including some screenshots, the dvd or bluRay cover and video trailers. My current approach is: When saving the files to the fileserver, I retrieve the movies random uuid (which is the primary key btw.). I then rename the files screenshot_[UUID]_1, screenshot_[UUID]_2 ... etc. Now, there are lots of other ways to handle this, like saving all filenames in a database or creating a dir structure on the fileserver for every uuid and, e.g., return all images in the "[uuid]/screenshots" folder via REST. I expect about 30k requests a day, so the service has to be pretty performant. Whats the best way to solve this?

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  • How to have operations with character/items on binary with concrete operations on C++?

    - by Piperoman
    I have the next problem. A item can have a lot of states: NORMAL = 0000000 DRY = 0000001 HOT = 0000010 BURNING = 0000100 WET = 0001000 COLD = 0010000 FROZEN = 0100000 POISONED= 1000000 A item can have some states at same time but not all of them Is impossible to be dry and wet at same time. If you COLD a WET item, it turns into FROZEN. If you HOT a WET item, it turns into NORMAL A item can be BURNING and POISON Etc. I have tried to set binary flags to states, and use AND to combine different states, checking before if it is possible or not to do it, or change to another status. Does there exist a concrete approach to solve this problem efficiently without having an interminable switch that checks every state with every new state? It is relatively easy to check 2 different states, but if there exists a third state it is not trivial to do.

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  • Documenting user interfaces in a mouse-less touch UI

    - by Daniel Cazzulino
    “Old” apps rely on mouse pointing and tooltips to explain what a given button is for. Maybe there is text associated with the button, but you can only put so much text without wasting useful screen state. More so in a phone or tablet app. I’ve seen a trend in Google apps where they put an overlay on top of the app the first time it runs, to explain how the various pieces of UI work. I have seen this also on my Nexus phone, but don’t have a screenshot. I don’t recall a way to actually bring that help overlay back again, so that’s maybe some built-in gesture that’s missing. Here’s what it looks like in Gmail, the first time you use the new compose layout:   I like the approach very much, and I think it’s something that should become standard part of mobile OS, and Windows, including a standard way to bring that help up from within any app....Read full article

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  • MVC shared model different required fields on different type

    - by kurasa
    I have a model called Car and depending on what type of Car the user select the view is presented differently. For example the user selects from a grid of different cars and depending if it is a Volvo or a Kia or a Ford the view must allow different fields to be editable. For example with a Volvo the color is editable and is mandatory but with a Kia it is not. I would like to use the one Car class to bind the view but want the client side validation to pick up the required fields based on what type of car. I want to go only to one Action method for the Update what is a good way to approach this problem...? create a base class and inherit from it? will this give me binding problems..?

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  • Service Layer - how broad should it be, and should it also be on the local application?

    - by BornToCode
    Background: I need to build a desktop application with some operations (CRUD and more) (=winforms), I need to make another application which will re-use some of the functions of the main application (=webforms). I understood that using service layer is the best approach here. If I understood correctly the service should be calling the function on the BL layer (correct me if I'm wrong) The dilemma: In my main winform UI - should I call the functions from the BL, or from the service? (please explain why) Should I create a service for every single function on the BL even if I need some of the functions only in one UI? for example - should I create services for all the CRUD operations, even though I need to re-use only update operation in the webform? YOUR HELP IS MUCH APPRECIATED

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  • What are the pros and cons of a non-fixed-interval update loop?

    - by akonsu
    I am studying various approaches to implementing a game loop and I have found this article. In the article the author implements a loop which, if the processing falls behind in time, skips frame renderings and just updates the game in a loop (the last variant called "Constant Game Speed independent of Variable FPS"). I do not understand why it is acceptable to call update_game() in a loop without making sure the update function is called at a particular interval. I do not see any value in doing this. I would think that in my game I want to be sure the game is updated periodically with a known period. So maybe it is worthwhile to have two threads, one would call update periodically, and the other one would redraw the game, also periodically? Would this be a good and practical approach? Of course I would need to synchronise the threads.

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  • Profiling and containing memory per system

    - by chadb
    I have been interesting in profiling and keeping a managed memory pool for each subsystem, so I could get statistic on how much memory was being used in something such as sounds or graphics. However, what is the best design for doing this? I was thinking of using multiple allocators and just using one per subsystem, however, that would result in global variables for my allocators (or so it would seem to me). Another approach I have seen/been suggested is to just overload new and pass in an allocator for a parameter. I had a similar question over on stackoverflow here with a bounty, however, it seems as if perhaps I was too vague or just there is not enough people with knowledge in the subject.

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  • Adding a list of "recent articles" affects SEO

    - by Groo
    We have a site which has a sidebar with sections (or "widgets" if you like) showing stuff like "Recent Articles", "Other Articles by this User", "Similar Articles" etc. The issue is, Google seems to take these links very seriously. In fact, if I have only a single article which is closely related to a certain phrase (and several other pages link to it in their sidebars), when I do a Google search, it lists all those other pages highlighting that one link to the page that should actually be the most relevant one. And these pages don't even mention the phrase anywhere else. It there a common approach with adding these sidebar links? For example, I might add them through ajax after the page is loaded, but then crawlers will have harder time finding them?

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  • Fixed Bid vs. T&amp;M &ndash; Take 2

    - by AjarnMark
    One of my most popular blog entries of all time is my Contracting Tips: Fixed Bid vs. T&M post from January, 2004.  This post consistently shows up in my referrers list, usually coming from a search engine.  Recently, Brent Ozar (@BrentO) wrote a great argument for why he always bills by the hour (a.k.a. Time & Materials or T&M) which itself was a response to Mark Richman’s (@mrichman) post on why he never bills by the hour (fixed bid).  Each article has good arguments, and I encourage you to read them both and choose the best approach for you. As for me, my experience parallels Brent’s and I historically have leaned toward the Time & Materials model.

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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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  • Disadvantages of a fake phpMyAdmin honeypot that causes ip blacklisting and robots.txt disallow/exclusion of the honeypot?

    - by Tchalvak
    I'm trying to figure out whether I should set up a honeypot system with a fake phpMyAdmin (site gets hits all the time with people spidering for insecurities with that app). My thought was to create a honeypot php script that would mimic a phpMyAdmin login, and then blacklist ips that hit that url (and aren't already whitelisted). I would then add the appropriate urls to the robots.txt so that spiders that actually respect my robots.txt wouldn't be caught by the blacklist. Are there disadvantages to this approach, do legit robots sometimes not respect robots.txt in certain circumstances, are there any problems with this that I should consider in advance?

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  • Is Domain Driven Design useful / productive for not so complex domains?

    - by Elijah
    When assessing a potential project at work, I suggested that it might be advantageous to use a domain driven design approach to its object model. The project does not have an excessively complex domain, so my coworker threw this at me: It has been said, that DDD is favorable in instances where there is a complex domain model (“...It applies whenever we are operating in a complex, intricate domain” Eric Evans). What I'm lost on is - how you define the complexity of a domain? Can it be defined by the number of aggregate roots in the domain model? Is the complexity of a domain in the interaction of objects? The domain that we are assessing is related online publishing and content management.

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  • Compizconfig Grid doesn't work under Ubuntu as virtual machine

    - by SoftTimur
    I have installed Ubuntu as virtual machine within Mac. I have installed VM tools. The approach in this link of Compizconfig Grid, which worked in my previous laptop where Ubuntu was not a virtual machine, does not work anymore. I set some shortcut, but no action is launched... Does anyone know why? The major functionality I need from Grid is tiling windows to left/right side of the screen... Does anyone know any alternative?

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  • How much configurability to give to users regarding concurrency?

    - by rwong
    This question is a narrowing-down of these related questions: How much effort should we spend to programming for multiple cores? Concurrency: How do you approach the design and debug the implementation? Given that each user's computers may have different performance characteristics with respect to calculations, memory, disk I/O bandwidth and network I/O bandwidth, and that it is difficult to implement an automated self-tuning system in your software, how much configurability should we give to the end-users so that they can find ways (by trial-and-error?) to improve our software's efficiency? If we give users the ability to change these settings, how do we give visual feedback to users so they can measure the performance changes?

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  • How to automate mysql backups?

    - by Patrick
    hi, I want to automatize the backup of my databases and files with cron. Should I add the following lines to crontab ? mysqldump -u root -pPASSWORD database_name | gzip > /home/backup/database_`date +\%m-\%d-\%Y`.sql.gz svn commit -m "Committing the working copy containing the database dump" 1) First of all, is this a good approach? 2) It is not clear how to specify the repository and the working copy with svn. 3) How can I run svn only when the mysqldump is done and not before ? Avoiding conflicts Any other tip ? thanks

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  • Real Time Monitoring System using .net [closed]

    - by sameer
    I need to develop the application which display the dashboard where data from various SQL DB is fetched from different servers and displayed. Now this need to happen real time we can have refresh time say 5 min. Here is my thought, suggest if anything is wrong. 1) To Develop the Windows Service to accumulate the data from various SQL Server Instance. 2) Then Persist those details into SQL DB from which Dashboard will displayed on the web page. 3) Fetch of data from Windows service will be trigger every x minutes. 4) SQL Server Instance details will be stored in SQL DB which Windows Service will be referring. Thus this approach make sense. Thanks..

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  • if ('constant' == $variable) vs. if ($variable == 'constant')

    - by Tom Auger
    Lately, I've been working a lot in PHP and specifically within the WordPress framework. I'm noticing a lot of code in the form of: if ( 1 == $options['postlink'] ) Where I would have expected to see: if ( $options['postlink'] == 1 ) Is this a convention found in certain languages / frameworks? Is there any reason the former approach is preferable to the latter (from a processing perspective, or a parsing perspective or even a human perspective?) Or is it merely a matter of taste? I have always thought it better when performing a test, that the variable item being tested against some constant is on the left. It seems to map better to the way we would ask the question in natural language: "if the cake is chocolate" rather than "if chocolate is the cake".

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  • How do I update wine in one wineprefix?

    - by Steve
    Does anyone know how I can go about updating the version of wine that one prefix uses without self-destructing everything in it? I want to bring it from 1.4 to 1.5.5 - I read on a forum that someone got the microphone working in Rosetta Stone with Ubuntu 12.04 and wine 1.5.5. Thanks for any guidance on this matter. :) http://ubuntuforums.org/showpost.php?p=11984993&postcount=20 Update: Issue resolved. Thanks to zuberuber I was able to approach the issue in a different light. :) I made a new prefix called "test" in PlayOnLinux. I compared the new prefix with the Rosetta prefix. It contained a PlayOnLinux.cfg file along with the reg files. It contained: ARCH=x86 VERSION=1.5.0 I copied this over to the Rosetta prefix and adjusted it: ARCH=x86 VERSION=1.4.1 After doing that, I was able to change it from 1.4.1 to 1.5.0. I confirmed it in the prefix's winecfg's About tab.

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  • SS7(M3UA, SCCP, TCAP, MAP) Stack

    - by Ammar Hameed
    I'm building an open source SMSC from scratch; it's almost finished, The SRI and the forwardSM operations are working, but I still have few things to do for the receiving part. I've built the SS7 stack already, but I'm using DB for saving the TCAP transactions IDs to be updated later to get/generate responses. My approach is this: I created memory table (heap table), saved the TCAP TID in the database, then compared the received TCAP TID with the TIDs saved in the database and then decide whether to end the TCAP session or continue. What is the best way to implement it? I'm thinking of doubly linked list that holds the TCAP TID. Am I going towards the right direction, or should I use another technique other than database or D-linked list? Should I leave it as it is, and let the database do the job for saving the TIDs? Please note that I'm using SCTP implementation available on Linux (lsctp) as a transport protocol, the language I'm using is C and the DB is MYSQL.

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  • Navigation in a #WP7 application with MVVM Light

    - by Laurent Bugnion
    In MVVM applications, it can be a bit of a challenge to send instructions to the view (for example a page) from a viewmodel. Thankfully, we have good tools at our disposal to help with that. In his excellent series “MVVM Light Toolkit soup to nuts”, Jesse Liberty proposes one approach using the MVVM Light messaging infrastructure. While this works fine, I would like to show here another approach using what I call a “view service”, i.e. an abstracted service that is invoked from the viewmodel, and implemented on the view. Multiple kinds of view services In fact, I use view services quite often, and even started standardizing them for the Windows Phone 7 applications I work on. If there is interest, I will be happy to show other such view services, for example Animation services, responsible to start/stop animations on the view. Dialog service, in charge of displaying messages to the user and gathering feedback. Navigation service, in charge of navigating to a given page directly from the viewmodel. In this article, I will concentrate on the navigation service. The INavigationService interface In most WP7 apps, the navigation service is used in quite a straightforward way. We want to: Navigate to a given URI. Go back. Be notified when a navigation is taking place, and be able to cancel. The INavigationService interface is quite simple indeed: public interface INavigationService { event NavigatingCancelEventHandler Navigating; void NavigateTo(Uri pageUri); void GoBack(); } Obviously, this interface can be extended if necessary, but in most of the apps I worked on, I found that this covers my needs. The NavigationService class It is possible to nicely pack the navigation service into its own class. To do this, we need to remember that all the PhoneApplicationPage instances use the same instance of the navigation service, exposed through their NavigationService property. In fact, in a WP7 application, it is the main frame (RootFrame, of type PhoneApplicationFrame) that is responsible for this task. So, our implementation of the NavigationService class can leverage this. First the class will grab the PhoneApplicationFrame and store a reference to it. Also, it registers a handler for the Navigating event, and forwards the event to the listening viewmodels (if any). Then, the NavigateTo and the GoBack methods are implemented. They are quite simple, because they are in fact just a gateway to the PhoneApplicationFrame. The whole class is as follows: public class NavigationService : INavigationService { private PhoneApplicationFrame _mainFrame; public event NavigatingCancelEventHandler Navigating; public void NavigateTo(Uri pageUri) { if (EnsureMainFrame()) { _mainFrame.Navigate(pageUri); } } public void GoBack() { if (EnsureMainFrame() && _mainFrame.CanGoBack) { _mainFrame.GoBack(); } } private bool EnsureMainFrame() { if (_mainFrame != null) { return true; } _mainFrame = Application.Current.RootVisual as PhoneApplicationFrame; if (_mainFrame != null) { // Could be null if the app runs inside a design tool _mainFrame.Navigating += (s, e) => { if (Navigating != null) { Navigating(s, e); } }; return true; } return false; } } Exposing URIs I find that it is a good practice to expose each page’s URI as a constant. In MVVM Light applications, a good place to do that is the ViewModelLocator, which already acts like a central point of setup for the views and their viewmodels. Note that in some cases, it is necessary to expose the URL as a string, for instance when a query string needs to be passed to the view. So for example we could have: public static readonly Uri MainPageUri = new Uri("/MainPage.xaml", UriKind.Relative); public const string AnotherPageUrl = "/AnotherPage.xaml?param1={0}&param2={1}"; Creating and using the NavigationService Normally, we only need one instance of the NavigationService class. In cases where you use an IOC container, it is easy to simply register a singleton instance. For example, I am using a modified version of a super simple IOC container, and so I can register the navigation service as follows: SimpleIoc.Register<INavigationService, NavigationService>(); Then, it can be resolved where needed with: SimpleIoc.Resolve<INavigationService>(); Or (more frequently), I simply declare a parameter on the viewmodel constructor of type INavigationService and let the IOC container do its magic and inject the instance of the NavigationService when the viewmodel is created. On supported platforms (for example Silverlight 4), it is also possible to use MEF. Or, of course, we can simply instantiate the NavigationService in the ViewModelLocator, and pass this instance as a parameter of the viewmodels’ constructor, injected as a property, etc… Once the instance has been passed to the viewmodel, it can be used, for example with: NavigationService.NavigateTo(ViewModelLocator.ComparisonPageUri); Testing Thanks to the INavigationService interface, navigation can be mocked and tested when the viewmodel is put under unit test. Simply implement and inject a mock class, and assert that the methods are called as they should by the viewmodel. Conclusion As usual, there are multiple ways to code a solution answering your needs. I find that view services are a really neat way to delegate view-specific responsibilities such as animation, dialogs and of course navigation to other classes through an abstracted interface. In some cases, such as the NavigationService class exposed here, it is even possible to standardize the implementation and pack it in a class library for reuse. I hope that this sample is useful! Happy coding. Laurent   Laurent Bugnion (GalaSoft) Subscribe | Twitter | Facebook | Flickr | LinkedIn

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  • Switching to HTTPS - redirect question

    - by seengee
    Following the recent Google announcements about improved ranking for sites running on https we have a number of clients asking about this. Is it safe to just 301 redirect all pages to their SSL equivalent, for example in a common PHP include file: if($_SERVER['HTTPS']!="on"){ $redirect= "https://".$_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI']; header("Location:$redirect",true,301); exit(); } Obviously I'm aware this is also possible within a .htaccess file but that cannot be modified in our case. Obviously all internal links would be switched to https:// links but obviously we need to sort out incoming links from Google and elsewhere. Is this a sound approach? Are there any other gotchas to be aware of?

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  • Using box2d DrawDebugData with multi layer scene ?

    - by Mr.Gando
    In my Game, a Scene is composed by several layers. Each layer has different camera transformations. This way I can have a layer at z=3 (GUI), z=2 (Monsters), z=1 (scrolling background), and this 3 layers compose my whole Scene. My render loop looks something like: renderLayer() applyTransformations() renderVisibleEntities() renderChildLayers() end If I call DrawDebugData() in the render loop, the whole b2world debug data will be rendered once for each layer in my scene, this generates a mess, because the "debug boxes" get duplicated, some of them get the camera transformations applied and some of them don't, etc. What I would like to do, would be to make DrawDebugData to draw only certain debug boxes. In that way, I could call something like b2world->DrawDebugDataForLayer(int layer_id) and call that on each layer like : renderLayer() applyTransformations() renderVisibleEntities() //Only render my corresponding layer debug data b2world->DrawDebugDataForLayer(layer_id) renderChildLayers() end Is there a way to subclass b2World so I could add this functionality ( specific to my game ) ? If not, what would be the best way to achieve this (Cocos2d uses a similar scene graph approach and box2d, but I'm not sure if debugDraw works in Cocos2d... ) Thanks

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