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  • Link Building - The Right Way

    The idea of link building is to generate quality inbound links pointed towards your websites. Nowadays search engines use this as a part of their algorithm with the help of which they can determine the significance of their websites.

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  • Silverlight Cream for March 26, 2010 -- #821

    - by Dave Campbell
    In this Issue: Max Paulousky, Christian Schormann, John Papa, Phani Raj, David Anson(-2-, -3-), Brad Abrams(-2-), and Jeff Wilcox(-2-, -3-). Shoutouts: Jeff Wilcox posted his material from mix and some preview TestFramework bits: Unit Testing Silverlight & Windows Phone Applications – talk now online At MIX10, Jeff Wilcox demo'd an app called "Peppermint"... here's the bleeding edge demo: “Peppermint” MIX demo sources Erik Mork and Co. have put out their weekly This Week In Silverlight 3.25.2010 Brad Abrams has all his materials posted for his MIX10 session Mix2010: Search Engine Optimization (SEO) for Microsoft Silverlight... including play-by-play of the demo and all source. Do you use Rooler? Well you should! Watch a video Pete Brown did with Pete Blois on Expression Blend, Windows Phone, Rooler Interested in Silverlight and XNA for WP7? Me too! Michael Klucher has a post outlining the two: Silverlight and XNA Framework Game Development and Compatibility From SilverlightCream.com: Modularity in Silverlight Applications - An Issue With ModuleInitializeException Max Paulousky has a truly ugly error trace listed by way of not having a reference listed, and the obvious simple solution. Next time he'll talk about the difficult situations. Using SketchFlow to Prototype for Windows Phone Christian Schormann has a tutorial up on using Expression Blend to develop for WP7 ... who better than Christian for that task?? Silverlight TV 18: WCF RIA Services Validation John Papa held forth with Nikhil Kothari on WCF RIA Services and validation just prior to MIX10, and was posted yesterday. Building SL3 applications using OData client Library with Vs 2010 RC Phani Raj walks through building an OData consumer in SL3, the first problem you're going to hit, and the easy solution to it. Tip: When creating a DependencyProperty, follow the handy convention of "wrapper+register+static+virtual" David Anson has a couple more of his 'Tips' up... this first is about Dependency Properties again... having a good foundation for all your Dependency Properties is a great way to avoid problems. Tip: Do not assign DependencyProperty values in a constructor; it prevents users from overriding them In the next post, David Anson talks about not assigning Dependency Property values in a constructor and gives one of the two ways to get around doing so. Tip: Set DependencyProperty default values in a class's default style if it's more convenient In his latest post, David Anson gives the second way to avoid setting a Dependency Property value in the constructor. Silverlight 4 + RIA Services - Ready for Business: Search Engine Optimization (SEO) Brad Abrams Abrams adds SEO to the tutorial series he's doing. He begins with his PDC09 session material on the subject and then takes off on a great detailed tutorial all with source. Silverlight 4 + RIA Services - Ready for Business: Localizing Business Application Brad Abrams then discusses localization and Silverlight in another detailed tutorial with all code included. Silverlight Toolkit and the Windows Phone: WrapPanel, and a few others Jeff Wilcox has a few WP7 posts I'm going to push today. This first is from earlier this week and is about using the Toolkit in WP7 and better than that, he includes the bits you need if all you want is the WrapPanel Data binding user settings in Windows Phone applications In the next one from yesterday, Jeff Wilcox demonstrates saving some user info in Isolated Storage to improve the user experience, and shares all the necessary plumbing files, and other external links as well. Displaying 2D QR barcodes in Windows Phone applications In a post from today, Jeff Wilcox ported his Silverlight 2D QR Barcode app from last year into WP7 ... just very cool... get the source and display your Microsoft Tag. Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone    MIX10

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  • Willy Rotstein on Supply Chain Planning

    - by sarah.taylor(at)oracle.com
    Each time a merchandiser, buyer or planner in Retail makes a business decision around assortment, inventory, pricing and promotions there is an opportunity to improve both Profitability and Customer Service. Improving decision making, however, has always been a tricky business for retailers.  I have worked in this space for more than 15 years. I began my career as an academic, at Imperial College London, and then broadened this interest with Retailers, aiming to optimize their merchandising and supply chain decisions. Planning the business and optimizing profit is a complex process. The complexity arises from the variety of people involved, the large number of decisions to take across all business processes, the uncertainty intrinsic to the retail environment as well as the volume of data available for analysis.  Things are not getting any easier either. The advent of multi-channel, social media and mobile is taking these complexities to a new level and presenting additional opportunities for those willing to exploit them. I guess it is due to the complexities of the decision making process that, over the last couple of years working with Oracle Retail, I have witnessed a clear trend around the deployment of planning systems. Retailers are aiming to simplify their decision making processes. They want to use one joined up planning platform across the business and enhance it with "actionable" data mining and optimization techniques. At Oracle Retail, we have a vibrant community of international retailers who regularly come together to discuss the big issues in retail planning. It is a combination of fashion, grocery and speciality retailers, all sharing their best practice vision for planning and optimizing merchandise decisions. As part of the Retail Exchange program, at the recent National Retail Federation event in New York, I jointly hosted a Planning dinner with Peter Fitzgerald from Google UK, Retail Division. Those retailers from our international planning community who were in New York for the annual NRF event were able to attend. The group comprised some of Europe's great International Retail brands.  All sectors were represented by organisations like Mango, LVMH, Ahold, Morrisons, Shop Direct and River Island. They confirmed the current importance of engaging with Planning and Optimization issues. In particular the impact of the internet was a key topic. We had a great debate about new retail initiatives.  Peter highlighted how mobility is changing retail - in particular with the new "local availability search" initiative. We also had an exciting discussion around the opportunities to improve merchandising using the new data that is becoming available from search, social media and ecommerce sites. It will be our focus to continue to help retailers translate this data into better results while keeping their business operations simple. New developments in "actionable" analytics and computing capacity make this a very exciting area today. Watch this space for my contributions on these topics which will be made available through this blog. Oracle Retail has a strong Planning community. if you are a category manager, a planner, a buyer, a merchandiser, a retail supplier or any retail executive with a keen interest in planning then you would be very welcome to join Oracle Retail's Planning Community. As part of our community you will be able to join our in-person and virtual events, download topical white papers and best practice information specifically tailored to your area of interest.  If anyone would like to register their interest in joining our community of retailers discussing planning then please contact me at [email protected]   Willy Rotstein, Oracle Retail

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  • Low level programming - what's in it for me?

    - by back2dos
    For years I have considered digging into what I consider "low level" languages. For me this means C and assembly. However I had no time for this yet, nor has it EVER been neccessary. Now because I don't see any neccessity arising, I feel like I should either just schedule some point in time when I will study the subject or drop the plan forever. My Position For the past 4 years I have focused on "web technologies", which may change, and I am an application developer, which is unlikely to change. In application development, I think usability is the most important thing. You write applications to be "consumed" by users. The more usable those applications are, the more value you have produced. In order to achieve good usability, I believe the following things are viable Good design: Well-thought-out features accessible through a well-thought-out user interface. Correctness: The best design isn't worth anything, if not implemented correctly. Flexibility: An application A should constantly evolve, so that its users need not switch to a different application B, that has new features, that A could implement. Applications addressing the same problem should not differ in features but in philosophy. Performance: Performance contributes to a good user experience. An application is ideally always responsive and performs its tasks reasonably fast (based on their frequency). The value of performance optimization beyond the point where it is noticeable by the user is questionable. I think low level programming is not going to help me with that, except for performance. But writing a whole app in a low level language for the sake of performance is premature optimization to me. My Question What could low level programming teach me, what other languages wouldn't teach me? Am I missing something, or is it just a skill, that is of very little use for application development? Please understand, that I am not questioning the value of C and assembly. It's just that in my everyday life, I am quite happy that all the intricacies of that world are abstracted away and managed for me (mostly by layers written in C/C++ and assembly themselves). I just don't see any concepts, that could be new to me, only details I would have to stuff my head with. So what's in it for me? My Conclusion Thanks to everyone for their answers. I must say, nobody really surprised me, but at least now I am quite sure I will drop this area of interest until any need for it arises. To my understanding, writing assembly these days for processors as they are in use in today's CPUs is not only unneccesarily complicated, but risks to result in poorer runtime performance than a C counterpart. Optimizing by hand is nearly impossible due to OOE, while you do not get all kinds of optimizations a compiler can do automatically. Also, the code is either portable, because it uses a small subset of available commands, or it is optimized, but then it probably works on one architecture only. Writing C is not nearly as neccessary anymore, as it was in the past. If I were to write an application in C, I would just as much use tested and established libraries and frameworks, that would spare me implementing string copy routines, sorting algorithms and other kind of stuff serving as exercise at university. My own code would execute faster at the cost of type safety. I am neither keen on reeinventing the wheel in the course of normal app development, nor trying to debug by looking at core dumps :D I am currently experimenting with languages and interpreters, so if there is anything I would like to publish, I suppose I'd port a working concept to C, although C++ might just as well do the trick. Again, thanks to everyone for your answers and your insight.

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  • .Net Reflector 6.5 EAP now available

    - by CliveT
    With the release of CLR 4 being so close, we’ve been working hard on getting the new C# and VB language features implemented inside Reflector. The work isn’t complete yet, but we have some of the features working. Most importantly, there are going to be changes to the Reflector object model, and we though it would be useful for people to see the changes and have an opportunity to comment on them. Before going any further, we should tell you what the EAP contains that’s different from the released version. A number of bugs have been fixed, mainly bugs that were raised via the forum. This is slightly offset by the fact that this EAP hasn’t had a whole lot of testing and there may have been new bugs introduced during the development work we’ve been doing. The C# language writer has been changed to display in and out co- and contra-variance markers on interfaces and delegates, and to display default values for optional parameters in method definitions. We also concisely display values passed by reference into COM calls. However, we do not change callsites to display calls using named parameters; this looks like hard work to get right. The forthcoming version of the C# language introduces dynamic types and dynamic calls. The new version of Reflector should display a dynamic call rather than the generated C#: dynamic target = MyTestObject(); target.Hello("Mum"); We have a few bugs in this area where we are not casting to dynamic when necessary. These have been fixed on a branch and should make their way into the next EAP. To support the dynamic features, we’ve added the types IDynamicMethodReferenceExpression, IDynamicPropertyIndexerExpression, and IDynamicPropertyReferenceExpression to the object model. These types, based on the versions without “Dynamic” in the name, reflect the fact that we don’t have full information about the method that is going to be called, but only have its name (as a string). These interfaces are going to change – in an internal version, they have been extended to include information about which parameter positions use runtime types and which use compile time types. There’s also the interface, IDynamicVariableDeclaration, that can be used to determine if a particular variable is used at dynamic call sites as a target. A couple of these language changes have also been added to the Visual Basic language writer. The new features are exposed only when the optimization level is set to .NET 4. When the level is set this high, the other standard language writers will simply display a message to say that they do not handle such an optimization level. Reflector Pro now has 4.0 as an optional compilation target and we have done some work to get the pdb generation right for these new features. The EAP version of Reflector no longer installs the add-in on startup. The first time you run the EAP, it displays the integration options dialog. You can use the checkboxes to select the versions of Visual Studio into which you want to install the EAP version. Note that you can only have one version of Reflector Pro installed in Visual Studio; if you install into a Visual Studio that has another version installed, the previous version will be removed. Please try it out and send your feedback to the EAP forum.

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  • Detect Unicode Usage in SQL Column

    One optimization you can make to a SQL table that is overly large is to change from nvarchar (or nchar) to varchar (or char).  Doing so will cut the size used by the data in half, from 2 bytes per character (+ 2 bytes of overhead for varchar) to only 1 byte per character.  However, you will lose the ability to store Unicode characters, such as those used by many non-English alphabets.  If the tables are storing user-input, and your application is or might one day be used internationally, its likely that using Unicode for your characters is a good thing.  However, if instead the data is being generated by your application itself or your development team (such as lookup data), and you can be certain that Unicode character sets are not required, then switching such columns to varchar/char can be an easy improvement to make. Avoid Premature Optimization If you are working with a lookup table that has a small number of rows, and is only ever referenced in the application by its numeric ID column, then you wont see any benefit to using varchar vs. nvarchar.  More generally, for small tables, you wont see any significant benefit.  Thus, if you have a general policy in place to use nvarchar/nchar because it offers more flexibility, do not take this post as a recommendation to go against this policy anywhere you can.  You really only want to act on measurable evidence that suggests that using Unicode is resulting in a problem, and that you wont lose anything by switching to varchar/char. Obviously the main reason to make this change is to reduce the amount of space required by each row.  This in turn affects how many rows SQL Server can page through at a time, and can also impact index size and how much disk I/O is required to respond to queries, etc.  If for example you have a table with 100 million records in it and this table has a column of type nchar(5), this column will use 5 * 2 = 10 bytes per row, and with 100M rows that works out to 10 bytes * 100 million = 1000 MBytes or 1GB.  If it turns out that this column only ever stores ASCII characters, then changing it to char(5) would reduce this to 5*1 = 5 bytes per row, and only 500MB.  Of course, if it turns out that it only ever stores the values true and false then you could go further and replace it with a bit data type which uses only 1 byte per row (100MB  total). Detecting Whether Unicode Is In Use So by now you think that you have a problem and that it might be alleviated by switching some columns from nvarchar/nchar to varchar/char but youre not sure whether youre currently using Unicode in these columns.  By definition, you should only be thinking about this for a column that has a lot of rows in it, since the benefits just arent there for a small table, so you cant just eyeball it and look for any non-ASCII characters.  Instead, you need a query.  Its actually very simple: SELECT DISTINCT(CategoryName)FROM CategoriesWHERE CategoryName <> CONVERT(varchar, CategoryName) Summary Gregg Stark for the tip. 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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  • Investigating on xVelocity (VertiPaq) column size

    - by Marco Russo (SQLBI)
      In January I published an article about how to optimize high cardinality columns in VertiPaq. In the meantime, VertiPaq has been rebranded to xVelocity: the official name is now “xVelocity in-memory analytics engine (VertiPaq)” but using xVelocity and VertiPaq when we talk about Analysis Services has the same meaning. In this post I’ll show how to investigate on columns size of an existing Tabular database so that you can find the most important columns to be optimized. A first approach can be looking in the DataDir of Analysis Services and look for the folder containing the database. Then, look for the biggest files in all subfolders and you will find the name of a file that contains the name of the most expensive column. However, this heuristic process is not very optimized. A better approach is using a DMV that provides the exact information. For example, by using the following query (open SSMS, open an MDX query on the database you are interested to and execute it) you will see all database objects sorted by used size in a descending way. SELECT * FROM $SYSTEM.DISCOVER_STORAGE_TABLE_COLUMN_SEGMENTS ORDER BY used_size DESC You can look at the first rows in order to understand what are the most expensive columns in your tabular model. The interesting data provided are: TABLE_ID: it is the name of the object – it can be also a dictionary or an index COLUMN_ID: it is the column name the object belongs to – you can also see ID_TO_POS and POS_TO_ID in case they refer to internal indexes RECORDS_COUNT: it is the number of rows in the column USED_SIZE: it is the used memory for the object By looking at the ration between USED_SIZE and RECORDS_COUNT you can understand what you can do in order to optimize your tabular model. Your options are: Remove the column. Yes, if it contains data you will never use in a query, simply remove the column from the tabular model Change granularity. If you are tracking time and you included milliseconds but seconds would be enough, round the data source column to the nearest second. If you have a floating point number but two decimals are good enough (i.e. the temperature), round the number to the nearest decimal is relevant to you. Split the column. Create two or more columns that have to be combined together in order to produce the original value. This technique is described in VertiPaq optimization article. Sort the table by that column. When you read the data source, you might consider sorting data by this column, so that the compression will be more efficient. However, this technique works better on columns that don’t have too many distinct values and you will probably move the problem to another column. Sorting data starting from the lower density columns (those with a few number of distinct values) and going to higher density columns (those with high cardinality) is the technique that provides the best compression ratio. After the optimization you should be able to reduce the used size and improve the count/size ration you measured before. If you are interested in a longer discussion about internal storage in VertiPaq and you want understand why this approach can save you space (and time), you can attend my 24 Hours of PASS session “VertiPaq Under the Hood” on March 21 at 08:00 GMT.

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  • Investigating on xVelocity (VertiPaq) column size

    - by Marco Russo (SQLBI)
      In January I published an article about how to optimize high cardinality columns in VertiPaq. In the meantime, VertiPaq has been rebranded to xVelocity: the official name is now “xVelocity in-memory analytics engine (VertiPaq)” but using xVelocity and VertiPaq when we talk about Analysis Services has the same meaning. In this post I’ll show how to investigate on columns size of an existing Tabular database so that you can find the most important columns to be optimized. A first approach can be looking in the DataDir of Analysis Services and look for the folder containing the database. Then, look for the biggest files in all subfolders and you will find the name of a file that contains the name of the most expensive column. However, this heuristic process is not very optimized. A better approach is using a DMV that provides the exact information. For example, by using the following query (open SSMS, open an MDX query on the database you are interested to and execute it) you will see all database objects sorted by used size in a descending way. SELECT * FROM $SYSTEM.DISCOVER_STORAGE_TABLE_COLUMN_SEGMENTS ORDER BY used_size DESC You can look at the first rows in order to understand what are the most expensive columns in your tabular model. The interesting data provided are: TABLE_ID: it is the name of the object – it can be also a dictionary or an index COLUMN_ID: it is the column name the object belongs to – you can also see ID_TO_POS and POS_TO_ID in case they refer to internal indexes RECORDS_COUNT: it is the number of rows in the column USED_SIZE: it is the used memory for the object By looking at the ration between USED_SIZE and RECORDS_COUNT you can understand what you can do in order to optimize your tabular model. Your options are: Remove the column. Yes, if it contains data you will never use in a query, simply remove the column from the tabular model Change granularity. If you are tracking time and you included milliseconds but seconds would be enough, round the data source column to the nearest second. If you have a floating point number but two decimals are good enough (i.e. the temperature), round the number to the nearest decimal is relevant to you. Split the column. Create two or more columns that have to be combined together in order to produce the original value. This technique is described in VertiPaq optimization article. Sort the table by that column. When you read the data source, you might consider sorting data by this column, so that the compression will be more efficient. However, this technique works better on columns that don’t have too many distinct values and you will probably move the problem to another column. Sorting data starting from the lower density columns (those with a few number of distinct values) and going to higher density columns (those with high cardinality) is the technique that provides the best compression ratio. After the optimization you should be able to reduce the used size and improve the count/size ration you measured before. If you are interested in a longer discussion about internal storage in VertiPaq and you want understand why this approach can save you space (and time), you can attend my 24 Hours of PASS session “VertiPaq Under the Hood” on March 21 at 08:00 GMT.

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  • ADO and Two Way Storage Tiering

    - by Andy-Oracle
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 We get asked the following question about Automatic Data Optimization (ADO) storage tiering quite a bit. Can you tier back to the original location if the data gets hot again? The answer is yes but not with standard Automatic Data Optimization policies, at least not reliably. That's not how ADO is meant to operate. ADO is meant to mirror a traditional view of Information Lifecycle Management (ILM) where data will be very volatile when first created, will become less active or cool, and then will eventually cease to be accessed at all (i.e. cold). I think the reason this question gets asked is because customers realize that many of their business processes are cyclical and the thinking goes that those segments that only get used during month end or year-end cycles could sit on lower cost storage when not being used. Unfortunately this doesn't fit very well with the ADO storage tiering model. ADO storage tiering is based on the amount of free and used space in the source tablespace. There are two parameters that control this behavior, TBS_PERCENT_USED and TBS_PERCENT_FREE. When the space in the tablespace exceeds the TBS_PERCENT_USED value then segments specified in storage tiering clause(s) can be moved until the percent of free space reaches the TBS_PERCENT_FREE value. It is worth mentioning that no checks are made for available space in the target tablespace. Now, it is certainly possible to create custom functions to control storage tiering, but this can get complicated. The biggest problem is insuring that there is enough space to move the segment back to tier 1 storage, assuming that that's the goal. This isn't as much of a problem when moving from tier 1 to tier 2 storage because there is typically more tier 2 storage available. At least that's the premise since it is supposed to be less costly, lower performing and higher capacity storage. In either case though, if there isn't enough space then the operation fails. In the case of a customized function, the question becomes do you attempt to free the space so the move can be made or do you just stop and return false so that the move cannot take place? This is really the crux of the issue. Once you cross into this territory you're really going to have to implement two-way hierarchical storage and the whole point of ADO was to provide automatic storage tiering. You're probably better off using heat map and/or business access requirements and building your own hierarchical storage management infrastructure if you really want two way storage tiering. /* 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:0in; mso-para-margin-bottom:.0001pt; 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-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

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  • Rethinking Oracle Optimizer Statistics for P6 Part 2

    - by Brian Diehl
    In the previous post (Part 1), I tried to draw some key insights about the relationship between P6 and Oracle Optimizer Statistics.  The first is that average cardinality has the greatest impact on query optimization and that the particular queries generated by P6 are more likely to use this average during calculations. The second is that these are statistics that are unlikely to change greatly over the life of the application. Ultimately, our goal is to get the best query optimization possible.  Or is it? Stability No application administrator wants to get the call at 9am that their application users cannot get there work done because everything is running slow. This is a possibility with a regularly scheduled nightly collection of statistics. It may not just be slow performance, but a complete loss of service because one or more queries are optimized poorly. Ideally, this should not be the case. The database optimizer should make better decisions with more up-to-date data. Better statistics may give incremental performance benefit. However, this benefit must be balanced against the potential cost of system down time.  It is stability that we ultimately desire and not absolute optimal performance. We do want the benefit from more accurate statistics and better query plans, but not at the risk of an unusable system. As a result, I've developed the following methodology around managing database statistics for the P6 database.  1. No Automatic Re-Gathering - The daily, weekly, or other interval of statistic gathering is unlikely to be beneficial. Quite the opposite. It is more likely to cause problems. 2. Smart Re-Gathering - The time to collect statistics is when things have changed significantly. For a new installation of P6, this is happening more often because the data is growing from a few rows to thousands and more. But for a mature system, the data is not changing significantly from week-to-week. There are times to collect statistics: New releases of the application Changes in the underlying hardware or software versions (ex. new Oracle RDBMS version) When additional user groups are added. The new groups may use the software in significantly different ways. After significant changes in the data. This may be monthly, quarterly or yearly.  3. Always Test - If you take away one thing from this post, it would be to always have a plan to test after changing statistics. In reality, statistics can be collected as often as you desire provided there are tests in place to verify that performance is the same or better. These might be automated tests or simply a manual script of application functions. 4. Have a Way Out - Never change the statistics without a way to return to the previous set. Think of the statistics as one part of the overall application code that also includes the source code--both application and RDBMS. It would be foolish to change to the new code without a way to get back to the previous version. In the final post, I will talk about the actual script I created for P6 PMDB and possible future direction for managing query performance. 

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  • Can you use gzip over SSL? And Connection: Keep-Alive headers

    - by magenta
    I'm evaluating the front end performance of a secure (SSL) web app here at work and I'm wondering if it's possible to compress text files (html/css/javascript) over SSL. I've done some googling around but haven't found anything specifically related to SSL. If it's possible, is it even worth the extra CPU cycles since responses are also being encrypted? Would compressing responses hurt performance? Also, I'm wanting to make sure we're keeping the SSL connection alive so we're not making SSL handshakes over and over. I'm not seeing Connection: Keep-Alive in the response headers. I do see Keep-Alive: 115 in the request headers but that's only keeping the connection alive for 115 milliseconds (seems like the app server is closing the connection after a single request is processed?) Wouldn't you want the server to be setting that response header for as long as the session inactivity timeout is? I understand browsers don't cache SSL content to disk so we're serving the same files over and over and over on subsequent visits even though nothing has changed. The main optimization recommendations are reducing the number of http requests, minification, moving scripts to bottom, image optimization, possible domain sharding (though need to weigh the cost of another SSL handshake), things of that nature.

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  • Iterating through String word at a time in Python

    - by AlgoMan
    I have a string buffer of a huge text file. I have to search a given words/phrases in the string buffer. Whats the efficient way to do it ? I tried using re module matches. But As i have a huge text corpus that i have to search through. This is taking large amount of time. Given a Dictionary of words and Phrases. I iterate through the each file, read that into string , search all the words and phrases in the dictionary and increment the count in the dictionary if the keys are found. One small optimization that we thought was to sort the dictionary of phrases/words with the max number of words to lowest. And then compare each word start position from the string buffer and compare the list of words. If one phrase is found, we don search for the other phrases (as it matched the longest phrase ,which is what we want) Can some one suggest how to go about word by word in the string buffer. (Iterate string buffer word by word) ? Also, Is there any other optimization that can be done on this ?

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  • efficiently determining if a polynomial has a root in the interval [0,T]

    - by user168715
    I have polynomials of nontrivial degree (4+) and need to robustly and efficiently determine whether or not they have a root in the interval [0,T]. The precise location or number of roots don't concern me, I just need to know if there is at least one. Right now I'm using interval arithmetic as a quick check to see if I can prove that no roots can exist. If I can't, I'm using Jenkins-Traub to solve for all of the polynomial roots. This is obviously inefficient since it's checking for all real roots and finding their exact positions, information I don't end up needing. Is there a standard algorithm I should be using? If not, are there any other efficient checks I could do before doing a full Jenkins-Traub solve for all roots? For example, one optimization I could do is to check if my polynomial f(t) has the same sign at 0 and T. If not, there is obviously a root in the interval. If so, I can solve for the roots of f'(t) and evaluate f at all roots of f' in the interval [0,T]. f(t) has no root in that interval if and only if all of these evaluations have the same sign as f(0) and f(T). This reduces the degree of the polynomial I have to root-find by one. Not a huge optimization, but perhaps better than nothing.

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  • Moving inserted container element if possible

    - by doublep
    I'm trying to achieve the following optimization in my container library: when inserting an lvalue-referenced element, copy it to internal storage; but when inserting rvalue-referenced element, move it if supported. The optimization is supposed to be useful e.g. if contained element type is something like std::vector, where moving if possible would give substantial speedup. However, so far I was unable to devise any working scheme for this. My container is quite complicated, so I can't just duplicate insert() code several times: it is large. I want to keep all "real" code in some inner helper, say do_insert() (may be templated) and various insert()-like functions would just call that with different arguments. My best bet code for this (a prototype, of course, without doing anything real): #include <iostream> #include <utility> struct element { element () { }; element (element&&) { std::cerr << "moving\n"; } }; struct container { void insert (const element& value) { do_insert (value); } void insert (element&& value) { do_insert (std::move (value)); } private: template <typename Arg> void do_insert (Arg arg) { element x (arg); } }; int main () { { // Shouldn't move. container c; element x; c.insert (x); } { // Should move. container c; c.insert (element ()); } } However, this doesn't work at least with GCC 4.4 and 4.5: it never prints "moving" on stderr. Or is what I want impossible to achieve and that's why emplace()-like functions exist in the first place?

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  • VS 2008 C++ build output?

    - by STingRaySC
    Why when I watch the build output from a VC++ project in VS do I see: 1Compiling... 1a.cpp 1b.cpp 1c.cpp 1d.cpp 1e.cpp [etc...] 1Generating code... 1x.cpp 1y.cpp [etc...] The output looks as though several compilation units are being handled before any code is generated. Is this really going on? I'm trying to improve build times, and by using pre-compiled headers, I've gotten great speedups for each ".cpp" file, but there is a relatively long pause during the "Generating Code..." message. I do not have "Whole Program Optimization" nor "Link Time Code Generation" turned on. If this is the case, then why? Why doesn't VC++ compile each ".cpp" individually (which would include the code generation phase)? If this isn't just an illusion of the output, is there cross-compilation-unit optimization potentially going on here? There don't appear to be any compiler options to control that behavior (I know about WPO and LTCG, as mentioned above). EDIT: The build log just shows the ".obj" files in the output directory, one per line. There is no indication of "Compiling..." vs. "Generating code..." steps. EDIT: I have confirmed that this behavior has nothing to do with the "maximum number of parallel project builds" setting in Tools - Options - Projects and Solutions - Build and Run. Nor is it related to the MSBuild project build output verbosity setting. Indeed if I cancel the build before the "Generating code..." step, the ".obj" files will not exist for the most recent set of "compiled" files. E.g., if I cancel the build during "c.cpp" above, I will see only "a.obj" and "b.obj".

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  • Thread management advice - Is TPL a good idea?

    - by Ian
    I'm hoping to get some advice on the use of thread managment and hopefully the task parallel library, because I'm not sure I've been going down the correct route. Probably best is that I give an outline of what I'm trying to do. Given a Problem I need to generate a Solution using a heuristic based algorithm. I start of by calculating a base solution, this operation I don't think can be parallelised so we don't need to worry about. Once the inital solution has been generated, I want to trigger n threads, which attempt to find a better solution. These threads need to do a couple of things: They need to be initalized with a different 'optimization metric'. In other words they are attempting to optimize different things, with a precedence level set within code. This means they all run slightly different calculation engines. I'm not sure if I can do this with the TPL.. If one of the threads finds a better solution that the currently best known solution (which needs to be shared across all threads) then it needs to update the best solution, and force a number of other threads to restart (again this depends on precedence levels of the optimization metrics). I may also wish to combine certain calculations across threads (e.g. keep a union of probabilities for a certain approach to the problem). This is probably more optional though. The whole system needs to be thread safe obviously and I want it to be running as fast as possible. I tried quite an implementation that involved managing my own threads and shutting them down etc, but it started getting quite complicated, and I'm now wondering if the TPL might be better. I'm wondering if anyone can offer any general guidance? Thanks...

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  • In sync query calls, one query causing other query to run slower. Why?

    - by Irchi
    Sorry for the long question, but I think this is an interesting situation and I couldn't find any explanations for it: I was involved in optimization of an application that performed a large number of sequential SELECT and INSERT statements on a single dedicated SQL Server database. The process needs to INSERT a large number of records into a table, but for each of them there should be some value mappings, which performed using SELECT statements on another table in the same database. For a specific execution, it took 90 minutes to run. I used a profiler (JProfiler - the application is Java-based) to determine how much time does each part of the application take. It yields that 60% of the time was spent on INSERT method calls, and almost 20% on SELECT calls (the rest distributed in other parts). After some trials, I came to this situation: I commented out the INSERT query that took 60% of the time. I was expecting for the total run time to be around 35 minutes, as I have removed 60% of the 90 minutes. But the whole process took the same 90 minutes (doing only SELECTs and nothing else), but each SELECT took longer this time! Everything was running sync, there were no async calls. And there was only one single thread of execution. SELECT and INSERT queries are very simple, and don't have anything special, and they are on different tables, but on the same DB. I tested with both the DB on the application machine, and on a remote network machine. I can't think of any explanation for this, as the Profiler (Application profiler, not SQL Profiler) reported the changes in the method call times, and by removing INSERT statements SELECT statements took longer to run. Can anyone give me some kind of explanation of what could have happened? (there can't be cache / query optimization stuff, because the queries were run in sync, and in a single thread, and it was far from affecting the cache this much) I should note that the bottleneck of the speed was in SQL server, using most of the CPU time.

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  • Ipsec config problem // openswan

    - by user90696
    I try to configure Ipsec on server with openswan as client. But receive error - possible, it's auth error. What I wrote wrong in config ? Thank you for answers. #1: STATE_MAIN_I2: sent MI2, expecting MR2 003 "f-net" #1: received Vendor ID payload [Cisco-Unity] 003 "f-net" #1: received Vendor ID payload [Dead Peer Detection] 003 "f-net" #1: ignoring unknown Vendor ID payload [ca917959574c7d5aed4222a9df367018] 003 "f-net" #1: received Vendor ID payload [XAUTH] 108 "f-net" #1: STATE_MAIN_I3: sent MI3, expecting MR3 003 "f-net" #1: discarding duplicate packet; already STATE_MAIN_I3 010 "f-net" #1: STATE_MAIN_I3: retransmission; will wait 20s for response 003 "f-net" #1: discarding duplicate packet; already STATE_MAIN_I3 003 "f-net" #1: discarding duplicate packet; already STATE_MAIN_I3 003 "f-net" #1: discarding duplicate packet; already STATE_MAIN_I3 010 "f-net" #1: STATE_MAIN_I3: retransmission; will wait 40s for response 031 "f-net" #1: max number of retransmissions (2) reached STATE_MAIN_I3. Possible authentication failure: no acceptable response to our first encrypted message 000 "f-net" #1: starting keying attempt 2 of at most 3, but releasing whack other side - Cisco ASA. parameters for my connection on our Linux server : VPN Gateway 8.*.*.* (Cisco ) Phase 1 Exchange Type Main Mode Identification Type IP Address Local ID 4.*.*.* (our Linux server IP) Remote ID 8.*.*.* (VPN server IP) Authentication PSK Pre Shared Key Diffie-Hellman Key Group DH 5 (1536 bit) or DH 2 (1024 bit) Encryption Algorithm AES 256 HMAC Function SHA-1 Lifetime 86.400 seconds / no volume limit Phase 2 Security Protocol ESP Connection Mode Tunnel Encryption Algorithm AES 256 HMAC Function SHA-1 Lifetime 3600 seconds / 4.608.000 kilobytes DPD / IKE Keepalive 15 seconds PFS off Remote Network 192.168.100.0/24 Local Network 1 10.0.0.0/16 ............... Local Network 5 current openswan config : # config setup klipsdebug=all plutodebug="control parsing" protostack=netkey nat_traversal=no virtual_private=%v4:10.0.0.0/8,%v4:192.168.0.0/16,%v4:172.16.0.0/12 oe=off nhelpers=0 conn f-net type=tunnel keyexchange=ike authby=secret auth=esp esp=aes256-sha1 keyingtries=3 pfs=no aggrmode=no keylife=3600s ike=aes256-sha1-modp1024 # left=4.*.*.* leftsubnet=10.0.0.0/16 leftid=4.*.*.* leftnexthop=%defaultroute right=8.*.*.* rightsubnet=192.168.100.0/24 rightid=8.*.*.* rightnexthop=%defaultroute auto=add

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  • All websites migrated from server running IIS6 to IIS7

    - by Leah
    Hi, I hope someone will be able to help me with this. We have recently migrated all of our clients' sites to a new server running IIS7 - all the sites were originally running on a server running IIS6. Ever since the migration, lots of our clients are reporting error messages. There seems to be quite a number of issues related to sending emails and also, we have had the following error message reported by several different clients: Server Error in '/' Application. -------------------------------------------------------------------------------- Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that <machineKey> configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Web.HttpException: Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that <machineKey> configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster. I have read elsewhere that this error can appear if a button is clicked before the whole page has finished loading. But as this error has now appeared on multiple sites and only since the server migration, it seems to me that it must be something else. I was wondering if someone could tell me if there is something specific which needs to be changed for .NET sites when sites are moved from a server running IIS6 to a server running IIS7? I don't deal with the actual servers very much so I'm afraid this is very much a grey area for me. Any help would be very much appreciated.

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  • Test A SSH Connection from Windows commandline

    - by IguanaMinstrel
    I am looking for a way to test if a SSH server is available from a Windows host. I found this one-liner, but it requires the a Unix/Linux host: ssh -q -o "BatchMode=yes" user@host "echo 2>&1" && echo "UP" || echo "DOWN" Telnet'ing to port 22 works, but that's not really scriptable. I have also played around with Plink, but I haven't found a way to get the functionality of the one-liner above. Does anyone know Plink enough to make this work? Are there any other windows based tools that would work? Please note that the SSH servers in question are behind a corporate firewall and are NOT internet accessible. Arrrg. Figured it out: C:\>plink -batch -v user@host Looking up host "host" Connecting to 10.10.10.10 port 22 We claim version: SSH-2.0-PuTTY_Release_0.62 Server version: SSH-2.0-OpenSSH_4.7p1-hpn12v17_q1.217 Using SSH protocol version 2 Server supports delayed compression; will try this later Doing Diffie-Hellman group exchange Doing Diffie-Hellman key exchange with hash SHA-256 Host key fingerprint is: ssh-rsa 1024 aa:aa:aa:aa:aa:aa:aa:aa:aa:aa:aa:aa:aa:aa:aa:aa Initialised AES-256 SDCTR client->server encryption Initialised HMAC-SHA1 client->server MAC algorithm Initialised AES-256 SDCTR server->client encryption Initialised HMAC-SHA1 server->client MAC algorithm Using username "user". Using SSPI from SECUR32.DLL Attempting GSSAPI authentication GSSAPI authentication initialised GSSAPI authentication initialised GSSAPI authentication loop finished OK Attempting keyboard-interactive authentication Disconnected: Unable to authenticate C:\>

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  • Estimating compressed file size using a list parameter

    - by Sai
    I am currently compressing a list of files from a directory in the following format: tar -cvjf test_1.tar.gz -T test_1.lst --no-recursion The above command will compress only those files mentioned in the list. I am doing this because this list is generated such that it fits a DVD. However, during compression the compression rate decreases the estimated file size and there is abundant space left in the DVD. This is something like a Knapsack algorithm. I would like to estimate the compressed file size and add some more files to the list. I found that it is possible to estimate file size using the following command: tar -cjf - Folder/ | wc -c This command does not take a list parameter. Is there a way to estimate compressed file size? I am also looking into options like perl scripts etc. Edit: I think I should provide more information since I have been doing a lot of web search. I came across a perl script(Link)that sort of emulates the Knapsack algorithm. The current problem with the above mentioned script is that it splits the files in their original state. When I compress the files after splitting them, there are opportunities for adding more files which I consider to be inefficient. There are 2 ways I could resolve the inefficiency: a) Compress individual files and save them in a directory using a script. The compressed file could provide a best estimate. I could generate a script using a folder of compressed files and use them on the uncompressed ones. b) Check whether the compressed file's size is less than the required size. If so, I should keep adding files until I meet the requirement. However, the addition of new files to the compressed file is an optimization problem by itself.

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  • EFS Remote Encryption

    - by Apoulet
    We have been trying to setup EFS across our domain. Unfortunately Reading/Writing file over network share does not work, we get an "Access Denied" error. Another worrying fact is that I managed to get it working for 1 machine but no other would work. The machines are all Windows 2008R2, running as VM under ESXi host. According to: http://technet.microsoft.com/en-us/library/bb457116.aspx#EHAA We setup the involved machine to be trusted for delegation The user are not restricted and can be trusted for delegation. The users have logged-in on both side and can read/write encrypted files without issues locally. I enabled Kerberos logging in the registry and this is the relevant logs that I get on the machine that has the encrypted files. In order for all certificate that the user possess (Only Key Name changes): Event ID 5058: Audit Success, "Other System Events" Key file operation. Subject: Security ID: {MyDOMAIN}\{MyID} Account Name: {MyID} Account Domain: {MyDOMAIN} Logon ID: 0xbXXXXXXX Cryptographic Parameters: Provider Name: Microsoft Software Key Storage Provider Algorithm Name: Not Available. Key Name: {CE885431-9B4F-47C2-8415-2D766B999999} Key Type: User key. Key File Operation Information: File Path: C:\Users\{MyID}\AppData\Roaming\Microsoft\Crypto\RSA\S-1-5-21-4585646465656-260371901-2912106767-1207\66099999999991e891f187e791277da03d_dfe9ecd8-31c4-4b0f-9b57-6fd3cab90760 Operation: Read persisted key from file. Return Code: 0x0[/code] Event ID 5061: Audit Faillure, "System Intergrity" [code]Cryptographic operation. Subject: Security ID: {MyDOMAIN}\{MyID} Account Name: {MyID} Account Domain: {MyDOMAIN} Logon ID: 0xbXXXXXXX Cryptographic Parameters: Provider Name: Microsoft Software Key Storage Provider Algorithm Name: RSA Key Name: {CE885431-9B4F-47C2-8415-2D766B999999} Key Type: User key. Cryptographic Operation: Operation: Open Key. Return Code: 0x8009000b Could this be related to this error from the CryptAcquireContext function NTE_BAD_KEY_STATE 0x8009000BL The user password has changed since the private keys were encrypted. The problem is that the users I using at the moment can not change their password.

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  • How does Windows 7 taskbar "color hot-tracking" feature calculate the colour to use?

    - by theyetiman
    This has intrigued me for quite some time. Does anyone know the algorithm Windows 7 Aero uses to determine the colour to use as the hot-tracking hover highlight on taskbar buttons for currently-running apps? It is definitely based on the icon of the app, but I can't see a specific pattern of where it's getting the colour value from. It doesn't seem to be any of the following: An average colour value from the entire icon, otherwise you would get brown all the time with multi-coloured icons like Chrome. The colour used the most in the image, otherwise you'd get yellow for the SQL Server Management Studio icon (6th from left). Also, the Chrome icon used red, green and yellow in equal measure. A colour located at certain pixel coordinates within the icon, because Chrome is red -indicating the top of the icon - and Notepad++ (2nd from right) is green - indicating the bottom of the icon. I asked this question on ux.stackoverflow.com and it got closed as off-topic, but someone answered with the following: As described by Raymond Chen in this MSDN blog article: Some people ask how it's done. It's really nothing special. The code just looks for the predominant color in the icon. (And, since visual designers are sticklers for this sort of thing, black, white, and shades of gray are not considered "colors" for the purpose of this calculation.) However I wasn't really satisfied with that answer because it doesn't explain how the "predominant" colour is calculated. Surely on the SQL Management Studio icon, the predominant colour, to my eyes at least, is yellow. Yet the highlight is green. I want to know, specifically, what the algorithm is.

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  • Windows media scaling/interpolation method

    - by MichaelH
    Usually in Windows, if videos or other media is upscaled from a certain resolution to a higher resolution (e.g. "monitor size"), a bilinear filtering algorithm or similar is used, such that the upscaled material doesn't look blocky. On my system however, the used interpolation algorithm changed from 'bilinear' to 'nearest neighbor' at some point, with the effect that upscaled videos (e.g. viewed in MPC or WMP, and also Skype video streams) and games (e.g. from PopCap) appear rather blocky. Not sure what the common factor between those is, could be DirectShow(?). I am not aware of having changed any setting that could have affected this state, in fact I am not even aware such a setting exists. I'm guesing that some installed software must have changed something on my computer. My computer is running Windows 7, but I had already experienced the same effect on an XP machine some while ago, where it changed back again to the more pleasing bilinear interpolation after a while, as magically as the first time. What could be wrong with this installation, and how can I change this upscaling interpolation behavior?

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  • How many guesses per second are possible against an encrypted disk? [closed]

    - by HappyDeveloper
    I understand that guesses per second depends on the hardware and the encryption algorithm, so I don't expect an absolute number as answer. For example, with an average machine you can make a lot (thousands?) of guesses per second for a hash created with a single md5 round, because md5 is fast, making brute force and dictionary attacks a real danger for most passwords. But if instead you use bcrypt with enough rounds, you can slow the attack down to 1 guess per second, for example. 1) So how does disk encryption usually work? This is how I imagine it, tell me if it is close to reality: When I enter the passphrase, it is hashed with a slow algorithm to generate a key (always the same?). Because this is slow, brute force is not a good approach to break it. Then, with the generated key, the disk is unencrypted on the fly very fast, so there is not a significant performance lose. 2) How can I test this with my own machine? I want to calculate the guesses per second my machine can make. 3) How many guesses per second are possible against an encrypted disk with the fastest PC ever so far?

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