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  • How could i send a html5 sqlite database from an iphone ?

    - by Edoc
    Hi everybody, i'm developing a webapp for iphone/ipod and using the client's side database. I want my webapp to work mainly offline and allow users to fill the database and at a certain point i'd like to send my database to a server to process and store all the informations. The problem is i can't find a proper way to send my tables to a server in order to fill its database with the one sent from the iphone. Does anyone has a clue ?

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  • How to utilize intranet bandwith

    - by tguclu
    Hi Is it possible to measure which web pages are visited mostyy and download their contenet so that people can access them offline. Basic scheme is: There will be client software on each user PC which will extract domain information on http requests and decide if it's already available on server or not. On the server side there will be another software which updates downloaded web pages. Do you think is this a good way of utilizing intranet bandwith ? thanks

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  • Java threads for the beginner

    - by Boba
    I've been trying to explain Java threading to a colleague who has never been exposed to multi-threaded applications, but apparently I'm not a very good teacher. Can anyone recommend a good online or offline resource that can explain threading in a simple, step-by-step manner? I know it's a complex topic, but surely there exists an article, book, or other explanation that can result in an "Aha! I get it, finally!" moment.

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  • simple and reliable centralized logging inside Amazon VPC

    - by Nakedible
    I need to set up centralized logging for a set of servers (10-20) in an Amazon VPC. The logging should be as to not lose any log messages in case any single server goes offline - or in the case that an entire availability zone goes offline. It should also tolerate packet loss and other normal network conditions without losing or duplicating messages. It should store the messages durably, at the minimum on two different EBS volumes in two availability zones, but S3 is a good place as well. It should also be realtime so that the messages arrive within seconds of their generation to two different availability zones. I also need to sync logfiles not generated via syslog, so a syslog-only centralized logging solution would not fulfill all the needs, although I guess that limitation could be worked around. I have already reviewed a few solutions, and I will list them here: Flume to Flume to S3: I could set up two logservers as Flume hosts which would store log messages either locally or in S3, and configure all the servers with Flume to send all messages to both servers, using the end-to-end reliability options. That way the loss of a single server shouldn't cause lost messages and all messages would arrive in two availability zones in realtime. However, there would need to be some way to join the logs of the two servers, deduplicating all the messages delivered to both. This could be done by adding a unique id on the sending side to each message and then write some manual deduplication runs on the logfiles. I haven't found an easy solution to the duplication problem. Logstash to Logstash to ElasticSearch: I could install Logstash on the servers and have them deliver to a central server via AMQP, with the durability options turned on. However, for this to work I would need to use some of the clustering capable AMQP implementations, or fan out the deliver just as in the Flume case. AMQP seems to be a yet another moving part with several implementations and no real guidance on what works best this sort of setup. And I'm not entirely convinced that I could get actual end-to-end durability from logstash to elasticsearch, assuming crashing servers in between. The fan-out solutions run in to the deduplication problem again. The best solution that would seem to handle all the cases, would be Beetle, which seems to provide high availability and deduplication via a redis store. However, I haven't seen any guidance on how to set this up with Logstash and Redis is one more moving part again for something that shouldn't be terribly difficult. Logstash to ElasticSearch: I could run Logstash on all the servers, have all the filtering and processing rules in the servers themselves and just have them log directly to a removet ElasticSearch server. I think this should bring me reliable logging and I can use the ElasticSearch clustering features to share the database transparently. However, I am not sure if the setup actually survives Logstash restarts and intermittent network problems without duplicating messages in a failover case or similar. But this approach sounds pretty promising. rsync: I could just rsync all the relevant log files to two different servers. The reliability aspect should be perfect here, as the files should be identical to the source files after a sync is done. However, doing an rsync several times per second doesn't sound fun. Also, I need the logs to be untamperable after they have been sent, so the rsyncs would need to be in append-only mode. And log rotations mess things up unless I'm careful. rsyslog with RELP: I could set up rsyslog to send messages to two remote hosts via RELP and have a local queue to store the messages. There is the deduplication problem again, and RELP itself might also duplicate some messages. However, this would only handle the things that log via syslog. None of these solutions seem terribly good, and they have many unknowns still, so I am asking for more information here from people who have set up centralized reliable logging as to what are the best tools to achieve that goal.

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  • What's the difference between find and findstr commands in Windows?

    - by Prashant Bhate
    In Windows, what are the differences between find and findstr commands? Both seems to search text in files: find c:\>find /? Searches for a text string in a file or files. FIND [/V] [/C] [/N] [/I] [/OFF[LINE]] "string" [[drive:][path]filename[ ...]] /V Displays all lines NOT containing the specified string. /C Displays only the count of lines containing the string. /N Displays line numbers with the displayed lines. /I Ignores the case of characters when searching for the string. /OFF[LINE] Do not skip files with offline attribute set. "string" Specifies the text string to find. [drive:][path]filename Specifies a file or files to search. If a path is not specified, FIND searches the text typed at the prompt or piped from another command. findstr c:\>findstr /? Searches for strings in files. FINDSTR [/B] [/E] [/L] [/R] [/S] [/I] [/X] [/V] [/N] [/M] [/O] [/P] [/F:file] [/C:string] [/G:file] [/D:dir list] [/A:color attributes] [/OFF[LINE]] strings [[drive:][path]filename[ ...]] /B Matches pattern if at the beginning of a line. /E Matches pattern if at the end of a line. /L Uses search strings literally. /R Uses search strings as regular expressions. /S Searches for matching files in the current directory and all subdirectories. /I Specifies that the search is not to be case-sensitive. /X Prints lines that match exactly. /V Prints only lines that do not contain a match. /N Prints the line number before each line that matches. /M Prints only the filename if a file contains a match. /O Prints character offset before each matching line. /P Skip files with non-printable characters. /OFF[LINE] Do not skip files with offline attribute set. /A:attr Specifies color attribute with two hex digits. See "color /?" /F:file Reads file list from the specified file(/ stands for console). /C:string Uses specified string as a literal search string. /G:file Gets search strings from the specified file(/ stands for console). /D:dir Search a semicolon delimited list of directories strings Text to be searched for. [drive:][path]filename Specifies a file or files to search. Use spaces to separate multiple search strings unless the argument is prefixed with /C. For example, 'FINDSTR "hello there" x.y' searches for "hello" or "there" in file x.y. 'FINDSTR /C:"hello there" x.y' searches for "hello there" in file x.y. Regular expression quick reference: . Wildcard: any character * Repeat: zero or more occurances of previous character or class ^ Line position: beginning of line $ Line position: end of line [class] Character class: any one character in set [^class] Inverse class: any one character not in set [x-y] Range: any characters within the specified range \x Escape: literal use of metacharacter x \<xyz Word position: beginning of word xyz\> Word position: end of word For full information on FINDSTR regular expressions refer to the online Command Reference.

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  • How to export SQL Server data from corrupted database (with disk write error)

    - by damitamit
    IT realised there was a disk write error on our production SQL Server 2005 and hence was causing the backups to fail. By the time they had realised this the nightly backup was old, so were not able to just restore the backup on another server. The database is still running and being used constantly. However DBCC CheckDB fails. Also the SQL Server backup task fails, Copy Database fails, Export Data Wizard fails. However it seems all the data can be read from the tables (i.e using bcp etc) Another observation I have made is that the Transaction Log is nearly double the size of the Database. (Does that mean all the changes arent being written to the MDF?) What would be the best plan of attack to get the database to a state where backups are working and the data is safe? Take the database offline and use the MDF/LDF to somehow create the database on another sql server? Export the data from the database using bcp. Create the database (use the Generate Scripts function on the corrupt db to create the schema on the new db) on another sql server and use bcp again to import the data. Some other option that is the right course of action in this situation? The IT manager says the data is safe as if the server fails, the data can be restored from the mdf/ldf. I'm not sure so insisted that we start exporting the data each night as a failsafe (using bcp for example). IT are also having issues on the hardware side of things as supposedly the disk error in on a virtualized disk and can't be rebuilt like a normal raid array (or something like that). Please excuse my use of incorrect terminology and incorrect assumptions on how Sql Server operates. I'm the application developer and have been called to help (as it seems IT know less about SQL Server than I do). Many Thanks, Amit Results of DBBC CheckDB: Msg 1823, Level 16, State 2, Line 1 A database snapshot cannot be created because it failed to start. Msg 7928, Level 16, State 1, Line 1 The database snapshot for online checks could not be created. Either the reason is given in a previous error or one of the underlying volumes does not support sparse files or alternate streams. Attempting to get exclusive access to run checks offline. Msg 5030, Level 16, State 12, Line 1 The database could not be exclusively locked to perform the operation. Msg 7926, Level 16, State 1, Line 1 Check statement aborted. The database could not be checked as a database snapshot could not be created and the database or table could not be locked. See Books Online for details of when this behavior is expected and what workarounds exist. Also see previous errors for more details. Msg 823, Level 24, State 3, Line 1 The operating system returned error 1(error not found) to SQL Server during a write at offset 0x00000674706000 in file 'G:\AX40_Dynamics_Live.mdf'. Additional messages in the SQL Server error log and system event log may provide more detail. This is a severe system-level error condition that threatens database integrity and must be corrected immediately. Complete a full database consistency check (DBCC CHECKDB). This error can be caused by many factors; for more information, see SQL Server Books Online.

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  • Google PageSpeed, optimizing Google's own elements

    - by mowgli
    I'm trying Google's PageSpeed online service Ironically, it's primarily highlighting Google's own services as something that needs improvement on my site 1) jQuery from Google: blocking. So I moved all javascript from <head> to the end of the document before </body>. That helped 2) Linking to external Google Font CSS (in <head>): blocking. But the font is critical to the design of the page and should load before much else 3) Google Analytics: Caching is not good. (Google has set it internally to 2 hours expiration). Don't know how to change this (this is also placed at the bottom of page) The Google Font is highlighted as a big priority to change. How can I fix this? Where/how should I call the the font?

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  • Windows 7 Phone Database Rapid Repository – V2.0 Beta Released

    - by SeanMcAlinden
    Hi All, A V2.0 beta has been released for the Windows 7 Phone database Rapid Repository, this can be downloaded at the following: http://rapidrepository.codeplex.com/ Along with the new View feature which greatly enhances querying and performance, various bugs have been fixed including a more serious bug with the caching that caused the GetAll() method to sometimes return inconsistent results (I’m a little bit embarrased by this bug). If you are currently using V1.0 in development, I would recommend swapping in the beta immediately. A full release will be available very shortly, I just need a few more days of testing and some input from other users/testers.   *Breaking Changes* The only real change is the RapidContext has moved under the main RapidRepository namespace. Various internal methods have been actually made ‘internal’ and replaced with a more friendly API (I imagine not many users will notice this change). Hope you like it Kind Regards, Sean McAlinden

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  • How Mary Meeker’s Latest Findings May Make You Re-Imagine Commerce

    - by Brenna Johnson-Oracle
    0 0 1 954 5439 Endeca Technologies 45 12 6381 14.0 Normal 0 false false false EN-US JA 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-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:12.0pt; font-family:Cambria; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin;} Today, Mary Meeker released her highly anticipated annual “Internet Trends” presentation for 2014. All 164 slides are jam-packed with pretty much everything you need to know about the state of the Internet. And as luck would have it, Oracle is staying ahead of these trends (but we’ll talk about that later). There were a few surprises, some stats to solidify what you likely already know, and Meeker’s novel observations about where we are all going. What interested me the most is not only how people are engaging in their personal lives, but how they engage with brands. As you could probably predict, Internet usage growth is slowing while tablet user and mobile data traffic growth continue their meteoric rise around the globe, with tremendous growth in underpenetrated markets like China, India, Brazil and Indonesia. Now hold those the “Internet is dead” comments. Keep in mind there’s still plenty of room to grow, and a multiscreen model is Meeker’s vision for our future. Despite 1.5x YOY growth for mobile traffic, mobile still only makes up about 23% of all traffic today. With tablet shipments easily outpacing figures for PCs even at their height (in 2007), mobile will only continue on it’s path, but won’t be everything to everyone. Mobile won’t replace every touchpoint, it’s just created our shorter attention spans and demand for simpler, more personal experiences. As Meeker points out TVs, tablets, PCs, and smartphones are used for different activities at present, but lines will blur (for example, 84% of smartphones owners use their device while watching TV). Day-to-day activities are being re-imagining through simple, beautiful user experiences. It seems like every day I discover a new way a brand/site/app made the most mundane or mounting task enjoyable and frictionless – and I’m not alone. Meeker points out the evolution of how we do everything from how we communicate, get information, use money, meet someone, get places, order a meal, and consume media is all done through new user interfaces that make day-to-day tasks simpler. This movement has caused just about everyone’s patience for a poor UX to take a nosedive. And it’s not just the digital user experience, technology is making a lot of people’s offline lives easier, and less expensive. Today 47% of online shopping utilizes free shipping— nearly half. And Meeker predicts same day local delivery will be the “next big thing” (and you can take a guess on who will own that). Content, Community and Commerce creates the “Internet Trifecta.” Meeker pointed out that when content, communities and commerce occur in a single experience it’s embraced by consumers, which translates to big dollars for brands. The magic happens when consumers can get inspired, research, and buy in a single experience. As the buying cycle has changed and touchpoints (Web, mobile, social, store) are no longer tied to “roles” or steps in the customer journey, brands must make all experiences (content and commerce) available in a single, adaptable experience. (We at Oracle Commerce have a lot to say on this topic – stay tuned!) And in what Meeker calls the “biggest re-imagination of all:” consumers enabled with smartphones and sensors are creating troves of findable and sharable data, which she says is in the early stages, by growing rapidly. She notes that transparency and patterns of consumers with this hardware (FYI - there are up to 10 sensors embedded in smartphones now) has created a Big Data treasure chest to be mined to improve business and the life of the consumer. The opportunities are endless. So what does it all mean for a company doing business online? Start thinking about how you can: Re-imagine your experience. Not your online experience and your mobile experience and your social experience – your overall experience. When consumers can research, buy, and advocate from anywhere (and their attention spans are at an all-time low) channels don’t exist. Enable simple and beautiful interactions informed by all of the online and offline data you leverage across your enterprise. Ethically leverage the endless supply of data (user generated content, clicks, purchases, in-store behavior, social activity) to make experiences more beautiful, more accurate, and more personalized (not to mention, more lucrative for you). Re-imagine content and commerce. Content and commerce must co-exist in a single destination where shoppers can get inspired, explore, research, share, and purchase in a collective experience. Think of how you can deliver an experience where all types of experiences (brand stories and commerce) adapt to every customer need. (Look for more on this topic coming soon). Re-imagine your reach. Look to Meeker’s findings to see how the global appetite for digital experiences is growing, but under-served in many places (i.e.: India, Mexico, Indonesia, Brazil, Philippines, etc.). Growing your online business to a new geography doesn’t have to mean starting from scratch or having an entirely new team manage the new endeavor. Expand using what you’ve already built in a multisite framework, with global language support. And of course, make sure it’s optimized for mobile! Re-imagine the possible. After every Meeker report, I’m always left with the thought “we are just at the beginning.” Everyday there is more data, more possibilities, more online consumers, and more opportunities to use new latest technology to get closer to your customers and be more successful. There’s a lot going on in our Product Development and Product Innovations groups to automate innovation for our customers, so that they can continue to stay ahead of these trends, without disrupting their business. Check out a recent interview with our Innovations Team on some of these new possibilities. Staying on track despite the seemingly endless possibilities out there is the hard part. Prioritizing where you will focus based on your unique brand promise, customer and goals is what you do best. To learn how Oracle Commerce can help your business achieve your goals check out oracle.com/commerce. Check out Meeker’s entire report here.

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  • TFS 2010 and the missing Area & Iterations (stale data) Issue

    - by andresv
    The symptom is this: you change some area or iteration in a TFS Project, but the change is not reflected (or updated) in VS or any other TFS Client. Well, it happens that TFS now has some clever caching mechanisms that need to be updated when you make a change like this, and those changes are propagated by some scheduled jobs TFS is continuously running in the Application Tier.  So, you you get this behavior, please check (and possibly restart) the "Visual Studio Team Foundation Background Job Agent" service. In my case, this service was logging a very odd "Object Reference Not Set" into the Windows Event Log, and a simple restart fixed it. Hope this is fixed by RTM...   (we are using the RC version). And by the way, if the job agent is broken there are some other things that stops working like email notifications. Best regards, Andrés G Vettori, CTO, VMBC  

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  • Tom Kyte szeminárium Budapesten, 2010. ápr. 19-20.

    - by Fekete Zoltán
    Még lehet jelentkezni Tom Kyte 2010-es budapesti szemináriumára, az itt található linkeken keresztül: - 2010. április 19-20., Budapesten tantermi szeminárium keretében. Témák: The top 10 - no 11 - new features of Oracle; Database 11g; All about binding; Materialized Views, Caching; Effective Indexing; Storage Techniques; Reorganizing objects - when and how. ASK TOM!

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  • Quick ways to boost performance and scalability of ASP.NET, WCF and Desktop Clients

    - by oazabir
    There are some simple configuration changes that you can make on machine.config and IIS to give your web applications significant performance boost. These are simple harmless changes but makes a lot of difference in terms of scalability. By tweaking system.net changes, you can increase the number of parallel calls that can be made from the services hosted on your servers as well as on desktop computers and thus increase scalability. By changing WCF throttling config you can increase number of simultaneous calls WCF can accept and thus make most use of your hardware power. By changing ASP.NET process model, you can increase number of concurrent requests that can be served by your website. And finally by turning on IIS caching and dynamic compression, you can dramatically increase the page download speed on browsers and and overall responsiveness of your applications. Read the CodeProject article for more details. http://www.codeproject.com/KB/webservices/quickwins.aspx Please vote for me if you find the article useful.

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  • GDC 2012: Best practices in developing a web game

    GDC 2012: Best practices in developing a web game (Pre-recorded GDC content) There's a new wave of console/pc/mobile game developers moving to the web looking to take advantage of the massive user base, along side of the powerful social graphs available there. The web as a platform is a very different technology stack than consoles / mobile, and as such, requires different development processes. This talk is targeted towards game developers who are looking to understand more about the development processes for web development including where to host your assets, proper techniques in caching to the persistant file store; dealing with sessions, storing user state, user login, game state storage, social graph integration, localization, audio, rendering, hardware detection and testing / distribution. If you're interested in developing a web game, you need to attend this talk! Speaker: Colt McAnlis From: GoogleDevelopers Views: 5149 131 ratings Time: 01:03:52 More in Science & Technology

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  • Oracle Database 12c Spatial: Vector Performance Acceleration

    - by Okcan Yasin Saygili-Oracle
    Most business information has a location component, such as customer addresses, sales territories and physical assets. Businesses can take advantage of their geographic information by incorporating location analysis and intelligence into their information systems. This allows organizations to make better decisions, respond to customers more effectively, and reduce operational costs – increasing ROI and creating competitive advantage. Oracle Database, the industry’s most advanced database,  includes native location capabilities, fully integrated in the kernel, for fast, scalable, reliable and secure spatial and massive graph applications. It is a foundation for deploying enterprise-wide spatial information systems and locationenabled business applications. Developers can extend existing Oracle-based tools and applications, since they can easily incorporate location information directly in their applications, workflows, and services. Spatial Features The geospatial data features of Oracle Spatial and Graph option support complex geographic information systems (GIS) applications, enterprise applications and location services applications. Oracle Spatial and Graph option extends the spatial query and analysis features included in every edition of Oracle Database with the Oracle Locator feature, and provides a robust foundation for applications that require advanced spatial analysis and processing in the Oracle Database. It supports all major spatial data types and models, addressing challenging business-critical requirements from various industries, including transportation, utilities, energy, public sector, defense and commercial location intelligence. Network Data Model Graph Features The Network Data Model graph explicitly stores and maintains a persistent data model withnetwork connectivity and provides network analysis capability such as shortest path, nearest neighbors, within cost and reachability. It loads partitioned networks into memory on demand, overcomingthe limitations of in-memory analysis. Partitioning massive networks into manageable sub-networkssimplifies the network analysis. RDF Semantic Graph Features RDF Semantic Graph has native support for World Wide Web Consortium standards. It has open, scalable, and secure features for storing RDF/OWL ontologies anddata; native inference with OWL 2, SKOS and user-defined rules; and querying RDF/OWL data withSPARQL 1.1, Java APIs, and SPARQLgraph patterns in SQL. Video: Oracle Spatial and Graph Overview Oracle spatial is embeded on oracle database product. So ,we can use oracle installer (OUI).The Oracle Universal Installer (OUI) is used to install Oracle Database software. OUI is a graphical user interface utility that enables you to view the Oracle software that is installed on your machine, install new Oracle Database software, and delete Oracle software that you no longer need to use. Online Help is available to guide you through the installation process. One of the installation options is to create a database. If you select database creation, OUI automatically starts Oracle Database Configuration Assistant (DBCA) to guide you through the process of creating and configuring a database. If you do not create a database during installation, you must invoke DBCA after you have installed the software to create a database. You can also use DBCA to create additional databases. For installing Oracle Database 12c you may check the Installing Oracle Database Software and Creating a Database tutorial under the Oracle Database 12c 2-Day DBA Series.You can always check if spatial is available in your database using  "select comp_id, version, status, comp_name from dba_registry where comp_id='SDO';"   One of the most notable improvements with Oracle Spatial and Graph 12c can be seen in performance increases in vector data operations. Enabling the Spatial Vector Acceleration feature (available with the Spatial option) dramatically improves the performance of commonly used vector data operations, such as sdo_distance, sdo_aggr_union, and sdo_inside. With 12c, these operations also run more efficiently in parallel than in prior versions through the use of metadata caching. For organizations that have been facing processing limitations, these enhancements enable developers to make a small set of configuration changes and quickly realize significant performance improvements. Results include improved index performance, enhanced geometry engine performance, optimized secondary filter optimizations for Spatial operators, and improved CPU and memory utilization for many advanced vector functions. Vector performance acceleration is especially beneficial when using Oracle Exadata Database Machine and other large-scale systems. Oracle Spatial and Graph vector performance acceleration builds on general improvements available to all SDO_GEOMETRY operations in these areas: Caching of index metadata, Concurrent update mechanisms, and Optimized spatial predicate selectivity and cost functions. These optimizations enable more efficient use of: CPU, Memory, and Partitioning Resulting in substantial query performance improvements.UsageTo accelerate the performance of spatial operators, it is recommended that you set the SPATIAL_VECTOR_ACCELERATION database system parameter to the value TRUE. (This parameter is authorized for use only by licensed Oracle Spatial users, and its default value is FALSE.) You can set this parameter for the whole system or for a single session. To set the value for the whole system, do either of the following:Enter the following statement from a suitably privileged account:   ALTER SYSTEM SET SPATIAL_VECTOR_ACCELERATION = TRUE;Add the following to the database initialization file (xxxinit.ora):   SPATIAL_VECTOR_ACCELERATION = TRUE;To set the value for the current session, enter the following statement from a suitably privileged account:   ALTER SESSION SET SPATIAL_VECTOR_ACCELERATION = TRUE; Checkout the complete list of new features on Oracle.com @ http://www.oracle.com/technetwork/database/options/spatialandgraph/overview/index.html Spatial and Graph Data Sheet (PDF) Spatial and Graph White Paper (PDF)

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  • Blogging platform for shared hosting?

    - by Ankit
    First of all, this is not for flame wars. So, please do not bash some blogging platform :P I have a shared hosting account. I want to setup a blog on it. Now, the thing is that as it is shared hosting, I do not have as much bandwidth as some expensive hosting. I have tried using Wordpress with the caching plugins configured. It still does not seem to speed it much. Also if I create a simple PHP website, the speed is fine. Can someone suggest me some lightweight platform?

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  • Best PHP-based web development 'stack' of 2011

    - by Jens Roland
    I have been building PHP-based web sites for many years, and lately it seems I'm discovering another interesting new tool or method once every few weeks. This begs the question - what is the current state of the art in PHP development stacks for the seasoned coder? I'm specifically interested in the following: High-performance web server Database MVC framework Build tool Revision control Continuous Integration Automated testing Non-persistent caching I'd like to optimize my stack for scalability and rapid development. I'm not looking for personal preference here, I'm looking for real, quantifiable reasons to pick this-over-that.

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  • Do Not Optimize Without Measuring

    - by Alois Kraus
    Recently I had to do some performance work which included reading a lot of code. It is fascinating with what ideas people come up to solve a problem. Especially when there is no problem. When you look at other peoples code you will not be able to tell if it is well performing or not by reading it. You need to execute it with some sort of tracing or even better under a profiler. The first rule of the performance club is not to think and then to optimize but to measure, think and then optimize. The second rule is to do this do this in a loop to prevent slipping in bad things for too long into your code base. If you skip for some reason the measure step and optimize directly it is like changing the wave function in quantum mechanics. This has no observable effect in our world since it does represent only a probability distribution of all possible values. In quantum mechanics you need to let the wave function collapse to a single value. A collapsed wave function has therefore not many but one distinct value. This is what we physicists call a measurement. If you optimize your application without measuring it you are just changing the probability distribution of your potential performance values. Which performance your application actually has is still unknown. You only know that it will be within a specific range with a certain probability. As usual there are unlikely values within your distribution like a startup time of 20 minutes which should only happen once in 100 000 years. 100 000 years are a very short time when the first customer tries your heavily distributed networking application to run over a slow WIFI network… What is the point of this? Every programmer/architect has a mental performance model in his head. A model has always a set of explicit preconditions and a lot more implicit assumptions baked into it. When the model is good it will help you to think of good designs but it can also be the source of problems. In real world systems not all assumptions of your performance model (implicit or explicit) hold true any longer. The only way to connect your performance model and the real world is to measure it. In the WIFI example the model did assume a low latency high bandwidth LAN connection. If this assumption becomes wrong the system did have a drastic change in startup time. Lets look at a example. Lets assume we want to cache some expensive UI resource like fonts objects. For this undertaking we do create a Cache class with the UI themes we want to support. Since Fonts are expensive objects we do create it on demand the first time the theme is requested. A simple example of a Theme cache might look like this: using System; using System.Collections.Generic; using System.Drawing; struct Theme { public Color Color; public Font Font; } static class ThemeCache { static Dictionary<string, Theme> _Cache = new Dictionary<string, Theme> { {"Default", new Theme { Color = Color.AliceBlue }}, {"Theme12", new Theme { Color = Color.Aqua }}, }; public static Theme Get(string theme) { Theme cached = _Cache[theme]; if (cached.Font == null) { Console.WriteLine("Creating new font"); cached.Font = new Font("Arial", 8); } return cached; } } class Program { static void Main(string[] args) { Theme item = ThemeCache.Get("Theme12"); item = ThemeCache.Get("Theme12"); } } This cache does create font objects only once since on first retrieve of the Theme object the font is added to the Theme object. When we let the application run it should print “Creating new font” only once. Right? Wrong! The vigilant readers have spotted the issue already. The creator of this cache class wanted to get maximum performance. So he decided that the Theme object should be a value type (struct) to not put too much pressure on the garbage collector. The code Theme cached = _Cache[theme]; if (cached.Font == null) { Console.WriteLine("Creating new font"); cached.Font = new Font("Arial", 8); } does work with a copy of the value stored in the dictionary. This means we do mutate a copy of the Theme object and return it to our caller. But the original Theme object in the dictionary will have always null for the Font field! The solution is to change the declaration of struct Theme to class Theme or to update the theme object in the dictionary. Our cache as it is currently is actually a non caching cache. The funny thing was that I found out with a profiler by looking at which objects where finalized. I found way too many font objects to be finalized. After a bit debugging I found the allocation source for Font objects was this cache. Since this cache was there for years it means that the cache was never needed since I found no perf issue due to the creation of font objects. the cache was never profiled if it did bring any performance gain. to make the cache beneficial it needs to be accessed much more often. That was the story of the non caching cache. Next time I will write something something about measuring.

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  • Aggregating cache data from OCEP in CQL

    - by Manju James
    There are several use cases where OCEP applications need to join stream data with external data, such as data available in a Coherence cache. OCEP’s streaming language, CQL, supports simple cache-key based joins of stream data with data in Coherence (more complex queries will be supported in a future release). However, there are instances where you may need to aggregate the data in Coherence based on input data from a stream. This blog describes a sample that does just that. For our sample, we will use a simplified credit card fraud detection use case. The input to this sample application is a stream of credit card transaction data. The input stream contains information like the credit card ID, transaction time and transaction amount. The purpose of this application is to detect suspicious transactions and send out a warning event. For the sake of simplicity, we will assume that all transactions with amounts greater than $1000 are suspicious. The transaction history is available in a Coherence distributed cache. For every suspicious transaction detected, a warning event must be sent with maximum amount, total amount and total number of transactions over the past 30 days, as shown in the diagram below. Application Input Stream input to the EPN contains events of type CCTransactionEvent. This input has to be joined with the cache with all credit card transactions. The cache is configured in the EPN as shown below: <wlevs:caching-system id="CohCacheSystem" provider="coherence"/> <wlevs:cache id="CCTransactionsCache" value-type="CCTransactionEvent" key-properties="cardID, transactionTime" caching-system="CohCacheSystem"> </wlevs:cache> Application Output The output that must be produced by the application is a fraud warning event. This event is configured in the spring file as shown below. Source for cardHistory property can be seen here. <wlevs:event-type type-name="FraudWarningEvent"> <wlevs:properties type="tuple"> <wlevs:property name="cardID" type="CHAR"/> <wlevs:property name="transactionTime" type="BIGINT"/> <wlevs:property name="transactionAmount" type="DOUBLE"/> <wlevs:property name="cardHistory" type="OBJECT"/> </wlevs:properties </wlevs:event-type> Cache Data Aggregation using Java Cartridge In the output warning event, cardHistory property contains data from the cache aggregated over the past 30 days. To get this information, we use a java cartridge method. This method uses Coherence’s query API on credit card transactions cache to get the required information. Therefore, the java cartridge method requires a reference to the cache. This may be set up by configuring it in the spring context file as shown below: <bean class="com.oracle.cep.ccfraud.CCTransactionsAggregator"> <property name="cache" ref="CCTransactionsCache"/> </bean> This is used by the java class to set a static property: public void setCache(Map cache) { s_cache = (NamedCache) cache; } The code snippet below shows how the total of all the transaction amounts in the past 30 days is computed. Rest of the information required by CardHistory object is calculated in a similar manner. Complete source of this class can be found here. To find out more information about using Coherence's API to query a cache, please refer Coherence Developer’s Guide. public static CreditHistoryData(String cardID) { … Filter filter = QueryHelper.createFilter("cardID = :cardID and transactionTime :transactionTime", map); CardHistoryData history = new CardHistoryData(); Double sum = (Double) s_cache.aggregate(filter, new DoubleSum("getTransactionAmount")); history.setTotalAmount(sum); … return history; } The java cartridge method is used from CQL as seen below: select cardID, transactionTime, transactionAmount, CCTransactionsAggregator.execute(cardID) as cardHistory from inputChannel where transactionAmount1000 This produces a warning event, with history data, for every credit card transaction over $1000. That is all there is to it. The complete source for the sample application, along with the configuration files, is available here. In the sample, I use a simple java bean to load the cache with initial transaction history data. An input adapter is used to create and send transaction events for the input stream.

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  • Silverlight Cream for January 11, 2011 -- #1024

    - by Dave Campbell
    1,000 blogposts is quite a few, but to die-hard geeks, 1000 isn't the number... 1K is the number, and today is my 1K blogpost! I've been working up to this for at least 11 months. Way back at MIX10, I approached some vendors about an idea I had. A month ago I contacted them and others, and everyone I contacted was very generous and supportive of my idea. My idea was not to run a contest, but blog as normal, and whoever ended up on my 1K post would get some swag... and I set a cut-off at 13 posts. So... blogging normally, I had some submittals, and then ran my normal process to pick up the next posts until I hit a total of 13. To provide a distribution channel for the swag, everyone on the list, please send me your snail mail (T-shirts) and email (licenses) addresses as soon as possible.   I'd like to thank the following generous sponsors for their contributions to my fun (in alphabetic order): and Rachel Hawley for contributing 4 Silverlight control sets First Floor Software and Koen Zwikstra for contributing 13 licenses for Silverlight Spy and Sara Faatz/Jason Beres for contributing 13 licenses for Silverlight Data Visualization controls and Svetla Stoycheva for contributing T-Shirts for everyone on the post and Ina Tontcheva for contributing 13 licenses for RadControls for Silverlight + RadControls for Windows Phone and Charlene Kozlan for contributing 1 combopack standard, 2 DataGrid for Silverlight, and 2 Listbox for Silverlight Standard And now finally...in this Issue: Nigel Sampson, Jeremy Likness, Dan Wahlin, Kunal Chowdhurry, Alex Knight, Wei-Meng Lee, Michael Crump, Jesse Liberty, Peter Kuhn, Michael Washington, Tau Sick, Max Paulousky, Damian Schenkelman Above the Fold: Silverlight: "Demystifying Silverlight Dependency Properties" Dan Wahlin WP7: "Using Windows Phone Gestures as Triggers" Nigel Sampson Expression Blend: "PathListBox: making data look cool" Alex Knight From SilverlightCream.com: Using Windows Phone Gestures as Triggers Nigel Sampson blogged about WP7 Gestures, the Toolkit, and using Gestures as Triggers, and actually makes it looks simple :) Jounce Part 9: Static and Dynamic Module Management Jeremy Likness has episode 9 of his explanation of his MVVM framework, Jounce, up... and a big discussion of Modules and Module Management from a Jounce perspective. Demystifying Silverlight Dependency Properties Dan Wahlin takes a page from one of his teaching opportunities, and shares his knowledge of Dependency Properties with us... beginning with what they are, defining them in code, and demonstrating their use. Customizing Silverlight ChildWindow Style using Blend Kunal Chowdhurry has a great post up about getting your Child Windows to match the look & feel of the rest of youra app... plus a bunch of Blend goodness thrown in. PathListBox: making data look cool File this post by Alex Knight in the 'holy crap' file along with the others in this series! ... just check out that cool Ticker Style Path ListBox at the top of the blog... too cool! Web Access in Windows Phone 7 Apps Wei-Meng Lee has the 3rd part of his series on WP7 development up and in this one is discussing Web Access... I mean *discussing* it... tons of detail, code, and explanation... great post. Prevent your Silverlight XAP file from caching in your browser. Michael Crump helps relieve stress on Silverlight developers everywhere by exploring how to avoid caching of your XAP in the browser... (WPFS) MVVM Light Toolkit: Soup To Nuts Part I Jesse Liberty continues his Windows Phone from Scratch series with a new segment exploring Laurent Bugnion's MVVMLight Toolkit beginning with acquiring and installing the toolkit, then proceeds to discuss linking the View and ViewModel, the ViewModel Locator, and page navigation. Silverlight: Making a DateTimePicker Peter Kuhn attacks a problem that crops up on the forums a lot -- a DateTimePicker control for Silverlight... following the "It's so simple to build one yourself" advice, he did so, and provides the code for all of us! Windows Phone 7 Animated Button Press Michael Washington took exception to button presses that gave no visual feedback and produced a behavior that does just that. Using TweetSharp in a Windows Phone 7 app Tau Sick demonstrates using TweetSharp to put a twitter feed into a WP7 app, as he did in "Hangover Helper"... all the instructions from getting Tweeetshaprt to the code necessary. Bindable Application Bar Extensions for Windows Phone 7 Max Paulousky has a post discussing some real extensions to the ApplicationBar for WP7.. he begins with a bindable application bar by Nicolas Humann that I've missed, probably because his blog is in French... and extends it to allow using DelegateCommand. How to: Load Prism modules packaged in a separate XAP file in an OOB application Damian Schenkelman posts about Prism, AppModules in separate XAPs and running OOB... if you've tried this, you know it's a hassle.. Damian has the solution. 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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  • Microsoft TechEd 2010 - Day 2 @ Bangalore

    - by sathya
    Microsoft TechEd 2010 - Day 2 @ Bangalore Today is the day 2 @ Microsoft TechEd 2010. We had lot of technical sessions as usual there were many tracks going on side by side and I was attending the Web simplified track, Which comprised of the following sessions :   Developing a scalable Media Application using ASP.NET MVC - This was a kind of little advanced stuff. Anyways I couldn't understand much because this was not my piece of cake and I havent worked on this before ASP.Net MVC Unplugged - This was really great because this session covered from the basics of MVC showing what is Model,View and Controller and how it worked and the speaker went into the details of the same. Building RESTful Applications with the Open Data Protocol - There were some concepts explained about this from the basics on how to build RESTful Services and it went on till some advanced configurations of the same. Developing Scalable Web Applications with AppFabric Caching - This session showed about the integration of AppFabric with the .Net Web Applications. Instead of using Inproc Sessions, we can use this AppFabric as a substitute for Caching and outofProc Session Storage without writing code and doing a little bit of configurations which brings in High Scalability, performance to our applications. (But unfortunately there were no demos for this session ) Deep Dive : WCF RIA Services - This session was also an interactive one, in this the speaker presented from the basics of WCF and took a Book Store Application as a sample and explained all details concepts on linking with RIA Services   Apart from these sessions, in between there happened some small events in the breaks like Some discussions about Technology, Innovations Music Jokes Mimicry, etc. And on doing all these things, the developers were given some kool gifts / goodies like USBs, T-Shirts, etc. And today I got a chance to do the following certification : (70-562) Microsoft Certified Technology Specialist in .NET 3.5 Web Applications Since I already have an MCTS in .NET 2.0, I wanted to do an MCPD and for doing the same I was required to do an update to my MCTS with the .NET 3.5 framework and I did the same I cleared it and now am an MCTS in .NET 3.5 Web Apps And on doing this I got a T-Shirt and they gave something called Learning $ of worth 30$. And in various stalls for attending each quiz or some game or some referrals we got some Learning $ which we can redeem later based on our Total Learning $. I got 105 $ which i was able to redeem and got a Microsoft Learning BagPack, 1 free Microsoft certification offer, a laptop light and an e-learning content activated. And after all these sessions and small events, we had something called Demo Extravaganza like I mentioned yesterday. This was a great funfilled event with lot of goodies for the attendees. There were some lucky draw which enabled 2 attendees to get Netbooks (Sponsored by Intel) and 1 attendee to get X-box (Sponsored by Citrix). After Choosing the raffle in the lucky draw they kept it on a device called Microsoft Surface which is a kind of big touch screen device and on putting the raffle on that it detected the code of the attendee and said intelligently how many sessions that person has attended and if he has attended more than 5 he got a Netbook and this was coded by a guy called Imran. Apart from they showed demos on : Research by 2 Tamilnadu students from Krishna Arts and Science college, taken 1200 photographs of their college from different angles and put that up in Bing maps using silverlight and linked with Photosynth, which showed a 3d view of their college based on the photos they uploaded Reasearch by Microsoft on Panaramic HD views of the images. One young guy from Microsoft Research showed a demo of this on Srivilliputhur Andal Temple, in Tamil Nadu and its history with a panoramic view of the temple and the near by places with narration of the historical information on the same and with the videos embedded in it with high definition images which we can zoom to a very detailed level. Some Demo on a business app with Silverlight, Business Intelligence (BI) and maps integrated. It showed the sales of a particular product across locations. Some kool demos by 2 geeks who used Robots to show their development talents. 2 Robots fought with each other 2 Robots danced in sync for the A.R. Rehman song Humma Humma... A dream home project by Raman. He is currently using the same in his home too. Robots are controlling his home currently. They showed a video on this. Here are the list of activities that Robot does for him When he reads a book, robot automatically scans that and shows that image of that person in the screen (TV or comp) in front of him. It shows a wikipedia about that person. It says that person is not in linked in. do you want to add him If he sees an IPL Match news in the book and smiles it understands he is interested in that and opens a website related to that and shows the current game and the scorecard. It cooks for him It cleans the room for him whenever he leaves the house when he is doing something if some intruder comes inside his house his computer automatically switches his screen showing the video of the person coming inside. When he wakes up it automatically opens up the system, loads his mails and the news by the side, etc. Some Demos on Microsoft Pivot. This was there in livelabs but it is now available in getpivot.com its a pivoting of the pictorial data based on some categories and filters on the searches that we do. And finally on filling up some feedback forms we got T-Shirts and Microsoft Visual Studio 2010 Training Kit CDs. Whats more on TechEd??? Stay tuned!!! Will update you soon on the other happenings!! PS : I typed a lot of content for more than a hour but I pressed a backspace and it went to the previous page and all my content were lost and I was not able to retrieve the same and I typed everything again.

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  • Hash Sum Mismatch using preseed (Ubuntu Server 12.04)

    - by xorma
    My install through Preseed fails at around 80% on Select and Install Software. In VT-4, I can see Hash Sum mismatch errors. This may be because I am going through a firewall which is caching files. There is no-cache option for apt but I can't seem to get it to work with Preseed. Have tried: d-i debian-installer/no-cache string true d-i apt-setup/no-cache boolean true d-i preseed/early_command string mkdir -p /target/etc/apt/apt.conf.d; echo "Acquire::http {No-Cache=True;};" > /target/etc/apt/apt.conf.d/no-cache but none of these are working. It appears that the early_command occurs too early so is over written once install starts. I'm not sure if the other commands are even correct. Anyone know what is the correct way of disabling achieving this through Preseed?

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  • Calling PowerShell from .NET

    I have been working with Windows Server AppFabric caching lately and have found it to be very impressive.  The more that I work with it the more that I can see areas that it can be utilized.  One of the things that will become quite evident as you start using it is that much of the setup and configuration is done through PowerShell cmdlets. I am in the process of putting together an application and I want the application to be able to create and pre-populate the cache.  As I looked...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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  • Good book/resource recommendation for HTML5 mobile game development?

    - by Greg Bala
    The problem: I am taking an existing, 5 year old, html based MMORTS game and "HTML5-ing" it, "AJAX-ing" it and most importantly, optimizing for mobile devices like iPhone, android etc. For these devices, the application will be packaged as a downloadable app that is a wrapper for a browser which actually shows the game.. The Question Looking for a good book, or books, or in-depth articles that would help me learn: what tools I have in iOS, andriod applications for optimizing an html based game. things like caching of images, etc what kind of connectivity, or interactivity I can expect between the html/javascript pages and the wrapper - can I play sounds in the wrapper by triggering them from javascript? etc tip and tricks to optimize html/html5 & Javascript application to run well on mobile devices ETC :) Any recommendations would be greatly appreciated!!

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  • Question about Target parameter of Matrix.CreateLookAt

    - by manning18
    I have a newbie question that's causing me a little bit of confusion when experimenting with cameras and reading other peoples implementations - does this parameter represent a point or a vector? In some examples I've seen people treat it like a specific point they are looking at (eg a position in the world), other times I see people caching the orientation of the camera in a rotation matrix and simply using the Matrix.Forward property as the "target", and other times it's a vector that's the result of targetPos - camPos and also I saw a camPos + orientation.Forward I was also just playing around with hard-coded target positions with same direction eg 1 to 10000 with no discernible difference in what I saw in the scene. Is the "Target" parameter actually a position or a direction (irrespective of magnitude)? Are there any subtle differences in behaviors, common mistakes or gotchas that are associated with what values you provide, or HOW you provide this paramter? Are all the methods I mentioned above equivalent? (sorry, I've only recently started and my math is still catching up)

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