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• SQLAuthority News – Great Time Spent at Great Indian Developers Summit 2014

  - by Pinal Dave

  The Great Indian Developer Conference (GIDS) is one of the most popular annual event held in Bangalore. This year GIDS is scheduled on April 22, 25. I will be presented total four sessions at this event and each session is very different from each other. Here are the details of four of my sessions, which I presented there. Pluralsight Shades This event was a great event and I had fantastic fun presenting a technology over here. I was indeed very excited that along with me, I had many of my friends presenting at the event as well. I want to thank all of you to attend my session and having standing room every single time. I have already sent resources in my newsletter. You can sign up for the newsletter over here. Indexing is an Art I was amazed with the crowd present in the sessions at GIDS. There was a great interest in the subject of SQL Server and Performance Tuning. Audience at GIDS I believe event like such provides a great platform to meet and share knowledge. Pinal at Pluralsight Booth Here are the abstract of the sessions which I had presented. They were recorded so at some point in time they will be available, but if you want the content of all the courses immediately, I suggest you check out my video courses on the same subject on Pluralsight. Indexes, the Unsung Hero Relevant Pluralsight Course Slow Running Queries are the most common problem that developers face while working with SQL Server. While it is easy to blame SQL Server for unsatisfactory performance, the issue often persists with the way queries have been written, and how Indexes has been set up. The session will focus on the ways of identifying problems that slow down SQL Server, and Indexing tricks to fix them. Developers will walk out with scripts and knowledge that can be applied to their servers, immediately post the session. Indexes are the most crucial objects of the database. They are the first stop for any DBA and Developer when it is about performance tuning. There is a good side as well evil side to indexes. To master the art of performance tuning one has to understand the fundamentals of indexes and the best practices associated with the same. We will cover various aspects of Indexing such as Duplicate Index, Redundant Index, Missing Index as well as best practices around Indexes. SQL Server Performance Troubleshooting: Ancient Problems and Modern Solutions Relevant Pluralsight Course Many believe Performance Tuning and Troubleshooting is an art which has been lost in time. However, truth is that art has evolved with time and there are more tools and techniques to overcome ancient troublesome scenarios. There are three major resources that when bottlenecked creates performance problems: CPU, IO, and Memory. In this session we will focus on High CPU scenarios detection and their resolutions. If time permits we will cover other performance related tips and tricks. At the end of this session, attendees will have a clear idea as well as action items regarding what to do when facing any of the above resource intensive scenarios. Developers will walk out with scripts and knowledge that can be applied to their servers, immediately post the session. To master the art of performance tuning one has to understand the fundamentals of performance, tuning and the best practices associated with the same. We will discuss about performance tuning in this session with the help of Demos. Pinal Dave at GIDS MySQL Performance Tuning – Unexplored Territory Relevant Pluralsight Course Performance is one of the most essential aspects of any application. Everyone wants their server to perform optimally and at the best efficiency. However, not many people talk about MySQL and Performance Tuning as it is an extremely unexplored territory. In this session, we will talk about how we can tune MySQL Performance. We will also try and cover other performance related tips and tricks. At the end of this session, attendees will not only have a clear idea, but also carry home action items regarding what to do when facing any of the above resource intensive scenarios. Developers will walk out with scripts and knowledge that can be applied to their servers, immediately post the session. To master the art of performance tuning one has to understand the fundamentals of performance, tuning and the best practices associated with the same. You will also witness some impressive performance tuning demos in this session. Hidden Secrets and Gems of SQL Server We Bet You Never Knew Relevant Pluralsight Course SQL Trio Session! It really amazes us every time when someone says SQL Server is an easy tool to handle and work with. Microsoft has done an amazing work in making working with complex relational database a breeze for developers and administrators alike. Though it looks like child’s play for some, the realities are far away from this notion. The basics and fundamentals though are simple and uniform across databases, the behavior and understanding the nuts and bolts of SQL Server is something we need to master over a period of time. With a collective experience of more than 30+ years amongst the speakers on databases, we will try to take a unique tour of various aspects of SQL Server and bring to you life lessons learnt from working with SQL Server. We will share some of the trade secrets of performance, configuration, new features, tuning, behaviors, T-SQL practices, common pitfalls, productivity tips on tools and more. This is a highly demo filled session for practical use if you are a SQL Server developer or an Administrator. The speakers will be able to stump you and give you answers on almost everything inside the Relational database called SQL Server. I personally attended the session of Vinod Kumar, Balmukund Lakhani, Abhishek Kumar and my favorite Govind Kanshi. Summary If you have missed this event here are two action items 1) Sign up for Resource Newsletter 2) Watch my video courses on Pluralsight Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: MySQL, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, SQLAuthority News, T SQL Tagged: GIDS

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• Breaking up the Workday– Overcoming the Workaholic Syndrome

  - by dwahlin

  Hi, my name’s Dan Wahlin and I’m a workaholic – I admit it. It’s good from the standpoint that I get a lot done but it also has a lot of cons associated with it as well that I’m not proud of. I literally can’t watch TV without feeling like I should be doing something more productive (although I have no problem going to see movies at a theater or watching sporting events – that’s my escape I guess). On vacation it’s sometimes difficult the first few days to just “let go” of work and enjoy the time with my family. I always feel like I should be checking email and following up with different business projects. Fortunately, my wife knows me really well after 17 years of marriage and “gently” restricts my usage of laptops and other gadgets while we’re out. She also reminds me that constantly burying my face in gadgets just isn’t cool and shows a distinct lack of self control. On a given day I typically put in between 12 (at a minimum) up to 16-18 hours working on projects. My company does .NET consulting (ASP.NET/jQuery, SharePoint and Silverlight) but we also do a lot in the training space so there’s always a client project, some new courseware or some other deliverable that has to be worked on. My normal process for handling that is to just work my butt off and see how much I can get done. That process has worked well for a long time but when you start realizing that your happiness comes from how much work you accomplished that day then you have a problem. That’s especially true if you have kids (which I do….two awesome boys). It’s almost as if working more hours feels like I’m more successful or something which is of course ridiculous. It may actually mean that I’m too distracted or disorganized. Lately I’ve realized that while I’m still productive and always meet my deadlines, I’m really burnt out by the afternoon and have lost some of the excitement I used to have. Part of that’s normal I think given that I’ve been doing this for close to 15 years now, but in thinking through it more I realized that I just need to get away from the desk and take a break. By far, the happiest time of my life was my childhood. Part of that was due to having awesome parents, having far less responsibility (a big factor I suspect), being able to hang-out with friends at school, playing sports, games, etc. but I think a big part of the overall happiness came from being outside a lot. I lived on my bike as a little kid and as I grew up I shared time between riding an ATV all over the place, shooting hoops on the basketball court, playing golf and working on a golf course (all outside work of course).  Being a software developer and trainer I generally spend 95% or more of my day indoors and only see the sun when driving from place to place or by looking out the window (that’s sad because I live in a suburb of Phoenix, AZ where it’s nearly always sunny). I haven’t looked into any scientific studies on the matter, but I’d be willing to bet there’s a direct correlation between overall productivity/happiness and being outside some throughout the day (sunny or not). But, I wasn’t sure what to do about it since I do have a lot of deadlines I need to meet after all. While talking with my wife last night I mentioned how I feel like I’m in a rut and want to get the “fun” back that I used to have. She immediately said that I need to start making time for breaks (a real quick fact – she’s a lot smarter than me and nearly always right). Of course my first thought was that I’d be less productive taking breaks. If I spend 2 hours just relaxing then I’m losing 2 hours of work. But, I thought about it more and realized that I’m probably less productive when I work 10+ hours and only take less than 30 minutes for a lunch break to relax a little. I bet my brain is screaming, “Please let me relax a little so I can figure out these problems you’re trying to resolve!”. So, starting today I’m going to try to break the workaholic habit and spend time outside of the office. That could mean sitting around outside, working out, golfing, or whatever. I’ve decided that no gadgets are allowed during that time and that I shouldn’t work for more than 4 hours straight without taking a break. I have no idea how my little “break the workaholic syndrome” experiment will go or how long it will last, but I’d be very interested in hearing from others on how they keep fresh and focused without working yourself to death. If you have any specific ideas, techniques or practices you follow please share them. There’s a lot more to life than work and some of us (and I’m thinking of myself specifically) need to take a long, hard look at what kind of balance we currently have. I’d hate to look back at my life when I’m 80 years old and say, “The only thing I did was work – I missed out on life!”.

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• SSIS: Building SQL databases on-the-fly using concatenated SQL scripts

  - by DrJohn

  Over the years I have developed many techniques which help automate the whole SQL Server build process. In my current process, where I need to build entire OLAP data marts on-the-fly, I make regular use of a simple but very effective mechanism to concatenate all the SQL Scripts together from my SSMS (SQL Server Management Studio) projects. This proves invaluable because in two clicks I can redeploy an entire SQL Server database with all tables, views, stored procedures etc. Indeed, I can also use the concatenated SQL scripts with SSIS to build SQL Server databases on-the-fly. You may be surprised to learn that I often redeploy the database several times per day, or even several times per hour, during the development process. This is because the deployment errors are logged and you can quickly see where SQL Scripts have object dependency errors. For example, after changing a table structure you may have forgotten to change any related views. The deployment log immediately points out all the objects which failed to build so you can fix and redeploy the database very quickly. The alternative approach (i.e. doing changes in the database directly using the SSMS UI) would require you to check all dependent objects before making changes. The chances are that you will miss something and wonder why your app returns the wrong data – a common problem caused by changing a table without re-creating dependent views. Using SQL Projects in SSMS A great many developers fail to make use of SQL Projects in SSMS (SQL Server Management Studio). To me they are invaluable way of organizing your SQL Scripts. The screenshot below shows a typical SSMS solution made up of several projects – one project for tables, another for views etc. The key point is that the projects naturally fall into the right order in file system because of the project name. The number in the folder or file name ensures that the projects the SQL scripts are concatenated together in the order that they need to be executed. Hence the script filenames start with 100, 110 etc. Concatenating SQL Scripts To concatenate the SQL Scripts together into one file, I use notepad.exe to create a simple batch file (see example screenshot) which uses the TYPE command to write the content of the SQL Script files into a combined file. As the SQL Scripts are in several folders, I simply use several TYPE command multiple times and append the output together. If you are unfamiliar with batch files, you may not know that the angled bracket (>) means write output of the program into a file. Two angled brackets (>>) means append output of this program into a file. So the command-line DIR > filelist.txt would write the content of the DIR command into a file called filelist.txt. In the example shown above, the concatenated file is called SB_DDS.sql If, like me you place the concatenated file under source code control, then the source code control system will change the file's attribute to "read-only" which in turn would cause the TYPE command to fail. The ATTRIB command can be used to remove the read-only flag. Using SQLCmd to execute the concatenated file Now that the SQL Scripts are all in one big file, we can execute the script against a database using SQLCmd using another batch file as shown below: SQLCmd has numerous options, but the script shown above simply executes the SS_DDS.sql file against the SB_DDS_DB database on the local machine and logs the errors to a file called SB_DDS.log. So after executing the batch file you can simply check the error log to see if your database built without a hitch. If you have errors, then simply fix the source files, re-create the concatenated file and re-run the SQLCmd to rebuild the database. This two click operation allows you to quickly identify and fix errors in your entire database definition.Using SSIS to execute the concatenated file To execute the concatenated SQL script using SSIS, you simply drop an Execute SQL task into your package and set the database connection as normal and then select File Connection as the SQLSourceType (as shown below). Create a file connection to your concatenated SQL script and you are ready to go.   Tips and TricksAdd a new-line at end of every fileThe most common problem encountered with this approach is that the GO statement on the last line of one file is placed on the same line as the comment at the top of the next file by the TYPE command. The easy fix to this is to ensure all your files have a new-line at the end.Remove all USE database statementsThe SQLCmd identifies which database the script should be run against.  So you should remove all USE database commands from your scripts - otherwise you may get unintentional side effects!!Do the Create Database separatelyIf you are using SSIS to create the database as well as create the objects and populate the database, then invoke the CREATE DATABASE command against the master database using a separate package before calling the package that executes the concatenated SQL script.    

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• Defining Your Online Segmentation and Targeting Strategy

  - by Christie Flanagan

  Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} A lot of times, companies will put online segmentation and targeting on the back burner because they don’t know where to start. Often, I’ve heard web managers say that their segments aren’t well understood yet, so they can’t really deliver personalized online experiences that are meaningful. This lack of complete understanding means that they don't really bother to try. But, I don’t think you necessarily need to have an elaborate segmentation and targeting strategy already in place to start delivering a more relevant online customer experience. Sometimes it helps to think of how segmentation and targeting might solve some of the challenges your sites visitors are currently experiencing on your web presence, rather than doing nothing and waiting until a fully baked segmentation strategy lands in your inbox.  For example, perhaps you have a broad and varied service offering that makes it difficult for site visitors to easily find the solutions that are most relevant for them.  How can segmentation and targeting help solve this problem?  Or maybe it’s like the airline I described in Monday’s post where the special deals featured on the home page are only relevant to site visitors from a couple of cities.  Couldn’t segmentation and targeting help them to highlight offers on their home page that are relevant to a larger share of their site visitors? Your early segmentation and targeting efforts do not need to be complicated.  There are simple ways to start delivering a more relevant online customer experience, even if you’re dealing with anonymous site visitors.  These include targeting content to site visitors based on: Referral: Deliver targeted content to your site visitors that is based on where they came from or the search term they used to find your site Behavior:  Deliver content to your site visitors that is related or similar to content they’ve clicked on already Location:  Deliver content your site visitors that is most relevant for their geographic location (this would solve that pesky airline home page problem described above) So as you can see, there really are some very simple ways in which you can start improving your online customer experience using very basic segmentation and targeting methods.  One thing to keep in mind as you start to define you segmentation and targeting strategy is that there are many different types of attributes or combinations of attributes upon which you can base your segmentation and targeting strategy.  In addition to referral, behavior and location, other attributes that you should consider are: Profile Information:  What profile information do you know about this customer already?  Perhaps they provided some information on their interests and preferences when they first registered with your site. Time:  What time is it and how does that impact what my site visitors are looking for or trying to do? Demographics: What are my site visitors’ ages, incomes or ethnicities? Which attributes you select to include in your segmentation strategy will depend on your unique business needs and objectives.  Attributes such as behavior or referral may not be the most important targeting criteria depending on your situation. For example, if you’re a newspaper you might know that certain visitors are sports fans based on their profile information.  You can create a segment for sports fans and target sports related content to that segment of your readership online.  Or perhaps, a reader is browsing stories that are related to politics; you can use that visitor’s behavior to assign him or her to a segment for those interested in politics. From there you can recommend more stories to that visitor based on their interest in politics. For an airline, the visitor’s location may be a more important attribute. By detecting the visitor’s location, you can assign them to an appropriate segment and then target special flights and offers to them based on their likely departure airport. As you can see, there are many practical ways that you can start improving the experience your customers receive on your web presence using fairly basic segmentation and targeting techniques. If you want to learn more about segmentation and targeting using Oracle’s web experience management solution, check out this helpful video that demonstrates these powerful capabilities in Oracle WebCenter Sites. ***** On Demand Webcast Featuring Brian Solis of Altimeter Group Trends such as the mobile web, social media, gamification and real-time are changing customer behavior and expectations. In this new environment, many businesses will struggle. Some will fall by the wayside, while others learn to adapt and thrive. Watch this on demand webcast with Altimeter Group digital analyst and author, Brian Solis, and discover what your organization needs to know about how to compete in the new era of Digital Darwinism. View now.

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• Infiniband: a highperformance network fabric - Part I

  - by Karoly Vegh

  Introduction:At the OpenWorld this year I managed to chat with interesting people again - one of them answering Infiniband deepdive questions with ease by coffee turned out to be one of Oracle's IB engineers, Ted Kim, who actually actively participates in the Infiniband Trade Association and integrates Oracle solutions with this highspeed network. This is why I love attending OOW. He granted me an hour of his time to talk about IB. This post is mostly based on that tech interview.Start of the actual post: Traditionally datatransfer between servers and storage elements happens in networks with up to 10 gigabit/seconds or in SANs with up to 8 gbps fiberchannel connections. Happens. Well, data rather trickles through.But nowadays data amounts grow well over the TeraByte order of magnitude, and multisocket/multicore/multithread Servers hunger data that these transfer technologies just can't deliver fast enough, causing all CPUs of this world do one thing at the same speed - waiting for data. And once again, I/O is the bottleneck in computing. FC and Ethernet can't keep up. We have half-TB SSDs, dozens of TB RAM to store data to be modified in, but can't transfer it. Can't backup fast enough, can't replicate fast enough, can't synchronize fast enough, can't load fast enough. The bad news is, everyone is used to this, like back in the '80s everyone was used to start compile jobs and go for a coffee. Or on vacation. The good news is, there's an alternative. Not so-called "bleeding-edge" 8gbps, but (as of now) 56. Not layers of overhead, but low latency. And it is available now. It has been for a while, actually. Welcome to the world of Infiniband. Short history:Infiniband was born as a result of joint efforts of HPAQ, IBM, Intel, Sun and Microsoft. They planned to implement a next-generation I/O fabric, in the 90s. In the 2000s Infiniband (from now on: IB) was quite popular in the high-performance computing field, powering most of the top500 supercomputers. Then in the middle of the decade, Oracle realized its potential and used it as an interconnect backbone for the first Database Machine, the first Exadata. Since then, IB has been booming, Oracle utilizes and supports it in a large set of its HW products, it is the backbone of the famous Engineered Systems: Exadata, SPARC SuperCluster, Exalogic, OVCA and even the new DB backup/recovery box. You can also use it to make servers talk highspeed IP to eachother, or to a ZFS Storage Appliance. Following Oracle's lead, even IBM has jumped the wagon, and leverages IB in its PureFlex systems, their first InfiniBand Machines.IB Structural Overview: If you want to use IB in your servers, the first thing you will need is PCI cards, in IB terms Host Channel Adapters, or HCAs. Just like NICs for Ethernet, or HBAs for FC. In these you plug an IB cable, going to an IB switch providing connection to other IB HCAs. Of course you're going to need drivers for those in your OS. Yes, these are long-available for Solaris and Linux. Now, what protocols can you talk over IB? There's a range of choices. See, IB isn't accepting package loss like Ethernet does, and hence doesn't need to rely on TCP/IP as a workaround for resends. That is, you still can run IP over IB (IPoIB), and that is used in various cases for control functionality, but the datatransfer can run over more efficient protocols - like native IB. About PCI connectivity: IB cards, as you see are fast. They bring low latency, which is just as important as their bandwidth. Current IB cards run at 56 gbit/s. That is slightly more than double of the capacity of a PCI Gen2 slot (of ~25 gbit/s). And IB cards are equipped usually with two ports - that is, altogether you'd need 112 gbit/s PCI slots, to be able to utilize FDR IB cards in an active-active fashion. PCI Gen3 slots provide you with around ~50gbps. This is why the most IB cards are configured in an active-standby way if both ports are used. Once again the PCI slot is the bottleneck. Anyway, the new Oracle servers are equipped with Gen3 PCI slots, an the new IB HCAs support those too. Oracle utilizes the QDR HCAs, running at 40gbp/s brutto, which translates to a 32gbp/s net traffic due to the 10:8 signal-to-data information ratio. Consolidation techniques: Technology never stops to evolve. Mellanox is working on the 100 gbps (EDR) version already, which will be optical, since signal technology doesn't allow EDR to be copper. Also, I hear you say "100gbps? I will never use/need that much". Are you sure? Have you considered consolidation scenarios, where (for example with Oracle Virtual Network) you could consolidate your platform to a high densitiy virtualized solution providing many virtual 10gbps interfaces through that 100gbps? Technology never stops to evolve. I still remember when a 10mbps network was impressively fast. Back in those days, 16MB of RAM was a lot. Now we usually run servers with around 100.000 times more RAM. If network infrastrucure speends could grow as fast as main memory capacities, we'd have a different landscape now :) You can utilize SRIOV as well for consolidation. That is, if you run LDoms (aka Oracle VM Server for SPARC) you do not have to add physical IB cards to all your guest LDoms, and you do not need to run VIO devices through the hypervisor either (avoiding overhead). You can enable SRIOV on those IB cards, which practically virtualizes the PCI bus, and you can dedicate Physical- and Virtual Functions of the virtualized HCAs as native, physical HW devices to your guests. See Raghuram's excellent post explaining SRIOV. SRIOV for IB is supported since LDoms 3.1.  This post is getting lengthier, so I will rename it to Part I, and continue it in a second post. 

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• Computer Networks UNISA - Chap 15 &ndash; Network Management

  - by MarkPearl

  After reading this section you should be able to Understand network management and the importance of documentation, baseline measurements, policies, and regulations to assess and maintain a network’s health. Manage a network’s performance using SNMP-based network management software, system and event logs, and traffic-shaping techniques Identify the reasons for and elements of an asset managements system Plan and follow regular hardware and software maintenance routines Fundamentals of Network Management Network management refers to the assessment, monitoring, and maintenance of all aspects of a network including checking for hardware faults, ensuring high QoS, maintaining records of network assets, etc. Scope of network management differs depending on the size and requirements of the network. All sub topics of network management share the goals of enhancing the efficiency and performance while preventing costly downtime or loss. Documentation The way documentation is stored may vary, but to adequately manage a network one should at least record the following… Physical topology (types of LAN and WAN topologies – ring, star, hybrid) Access method (does it use Ethernet 802.3, token ring, etc.) Protocols Devices (Switches, routers, etc) Operating Systems Applications Configurations (What version of operating system and config files for serve / client software) Baseline Measurements A baseline is a report of the network’s current state of operation. Baseline measurements might include the utilization rate for your network backbone, number of users logged on per day, etc. Baseline measurements allow you to compare future performance increases or decreases caused by network changes or events with past network performance. Obtaining baseline measurements is the only way to know for certain whether a pattern of usage has changed, or whether a network upgrade has made a difference. There are various tools available for measuring baseline performance on a network. Policies, Procedures, and Regulations Following rules helps limit chaos, confusion, and possibly downtime. The following policies and procedures and regulations make for sound network management. Media installations and management (includes designing physical layout of cable, etc.) Network addressing policies (includes choosing and applying a an addressing scheme) Resource sharing and naming conventions (includes rules for logon ID’s) Security related policies Troubleshooting procedures Backup and disaster recovery procedures In addition to internal policies, a network manager must consider external regulatory rules. Fault and Performance Management After documenting every aspect of your network and following policies and best practices, you are ready to asses you networks status on an on going basis. This process includes both performance management and fault management. Network Management Software To accomplish both fault and performance management, organizations often use enterprise-wide network management software. There various software packages that do this, each collect data from multiple networked devices at regular intervals, in a process called polling. Each managed device runs a network management agent. So as not to affect the performance of a device while collecting information, agents do not demand significant processing resources. The definition of a managed devices and their data are collected in a MIB (Management Information Base). Agents communicate information about managed devices via any of several application layer protocols. On modern networks most agents use SNMP which is part of the TCP/IP suite and typically runs over UDP on port 161. Because of the flexibility and sophisticated network management applications are a challenge to configure and fine-tune. One needs to be careful to only collect relevant information and not cause performance issues (i.e. pinging a device every 5 seconds can be a problem with thousands of devices). MRTG (Multi Router Traffic Grapher) is a simple command line utility that uses SNMP to poll devices and collects data in a log file. MRTG can be used with Windows, UNIX and Linux. System and Event Logs Virtually every condition recognized by an operating system can be recorded. This is typically done using event logs. In Windows there is a GUI event log viewer. Similar information is recorded in UNIX and Linux in a system log. Much of the information collected in event logs and syslog files does not point to a problem, even if it is marked with a warning so it is important to filter your logs appropriately to reduce the noise. Traffic Shaping When a network must handle high volumes of network traffic, users benefit from performance management technique called traffic shaping. Traffic shaping involves manipulating certain characteristics of packets, data streams, or connections to manage the type and amount of traffic traversing a network or interface at any moment. Its goals are to assure timely delivery of the most important traffic while offering the best possible performance for all users. Several types of traffic prioritization exist including prioritizing traffic according to any of the following characteristics… Protocol IP address User group DiffServr VLAN tag in a Data Link layer frame Service or application Caching In addition to traffic shaping, a network or host might use caching to improve performance. Caching is the local storage of frequently needed files that would otherwise be obtained from an external source. By keeping files close to the requester, caching allows the user to access those files quickly. The most common type of caching is Web caching, in which Web pages are stored locally. To an ISP, caching is much more than just convenience. It prevents a significant volume of WAN traffic, thus improving performance and saving money. Asset Management Another key component in managing networks is identifying and tracking its hardware. This is called asset management. The first step to asset management is to take an inventory of each node on the network. You will also want to keep records of every piece of software purchased by your organization. Asset management simplifies maintaining and upgrading the network chiefly because you know what the system includes. In addition, asset management provides network administrators with information about the costs and benefits of certain types of hardware or software. Change Management Networks are always in a stage of flux with various aspects including… Software changes and patches Client Upgrades Shared Application Upgrades NOS Upgrades Hardware and Physical Plant Changes Cabling Upgrades Backbone Upgrades For a detailed explanation on each of these read the textbook (Page 750 – 761)

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• Myths about Coding Craftsmanship part 2

  - by tom

  Myth 3: The source of all bad code is inept developers and stupid people When you review code is this what you assume?  Shame on you.  You are probably making assumptions in your code if you are assuming so much already.  Bad code can be the result of any number of causes including but not limited to using dated techniques (like boxing when generics are available), not following standards (“look how he does the spacing between arguments!” or “did he really just name that variable ‘bln_Hello_Cats’?”), being redundant, using properties, methods, or objects in a novel way (like switching on button.Text between “Hello World” and “Hello World “ //clever use of space character… sigh), not following the SOLID principals, hacking around assumptions made in earlier iterations / hacking in features that should be worked into the overall design.  The first two issues, while annoying are pretty easy to spot and can be fixed so easily.  If your coding team is made up of experienced professionals who are passionate about staying current then these shouldn’t be happening.  If you work with a variety of skills, backgrounds, and experience then there will be some of this stuff going on.  If you have an opportunity to mentor such a developer who is receptive to constructive criticism don’t be a jerk; help them and the codebase will improve.  A little patience can improve the codebase, your work environment, and even your perspective. The novelty and redundancy I have encountered has often been the use of creativity when language knowledge was perceived as unavailable or too time consuming.  When developers learn on the job you get a lot of this.  Rather than going to MSDN developers will use what they know.  Depending on the constraints of their assignment hacking together what they know may seem quite practical.  This was not stupid though I often wonder how much time is actually “saved” by hacking.  These issues are often harder to untangle if we ever do.  They can also grow out of control as we write hack after hack to make it work and get back to some development that is satisfying. Hacking upon an existing hack is what I call “feeding the monster”.  Code monsters are anti-patterns and hacks gone wild.  The reason code monsters continue to get bigger is that they keep growing in scope, touching more and more of the application.  This is not the result of dumb developers. It is probably the result of avoiding design, not taking the time to understand the problems or anticipate or communicate the vision of the product.  If our developers don’t understand the purpose of a feature or product how do we expect potential customers to do so? Forethought and organization are often what is missing from bad code.  Developers who do not use the SOLID principals should be encouraged to learn these principals and be given guidance on how to apply them.  The time “saved” by giving hackers room to hack will be made up for and then some. Not as technical debt but as shoddy work that if not replaced will be struggled with again and again.  Bad code is not the result of dumb developers (usually) it is the result of trying to do too much without the proper resources and neglecting the right thing that needs doing with the first thoughtless thing that comes into our heads. Object oriented code is all about relationships between objects.  Coders who believe their coworkers are all fools tend to write objects that are difficult to work with, not eager to explain themselves, and perform erratically and irrationally.  If you constantly find you are surrounded by idiots you may want to ask yourself if you are being unreasonable, if you are being closed minded, of if you have chosen the right profession.  Opening your mind up to the idea that you probably work with rational, well-intentioned people will probably make you a better coder and it might even make you less grumpy.  If you are surrounded by jerks who do not engage in the exchange of ideas who do not care about their customers or the durability of the code you are building together then I suggest you find a new place to work.  Myth 4: Customers don’t care about “beautiful” code Craftsmanship is customer focused because it means that the job was done right, the product will withstand the abuse, modifications, and scrutiny of our customers.  Users can appreciate a predictable timeline for a release, a product delivered on time and on budget, a feature set that does not interfere with the task(s) it is supporting, quick turnarounds on exception messages, self healing issues, and less issues.  These are all hindered by skimping on craftsmanship.  When we write data access and when we write reusable code.   What do you think?  Does bad code come primarily from low IQ individuals?  Do customers care about beautiful code?

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• T-SQL Tuesday #34: Help! I Need Somebody!

  - by Most Valuable Yak (Rob Volk)

  Welcome everyone to T-SQL Tuesday Episode 34!  When last we tuned in, Mike Fal (b|t) hosted Trick Shots.  These highlighted techniques or tricks that you figured out on your own which helped you understand SQL Server better. This month, I'm asking you to look back this past week, year, century, or hour...to a time when you COULDN'T figure it out.  When you were stuck on a SQL Server problem and you had to seek help. In the beginning... SQL Server has changed a lot since I started with it.  <Cranky Old Guy> Back in my day, Books Online was neither.  There were no blogs. Google was the third-place search site. There were perhaps two or three community forums where you could ask questions.  (Besides the Microsoft newsgroups...which you had to access with Usenet.  And endure the wrath of...Celko.)  Your "training" was reading a book, made from real dead trees, that you bought from your choice of brick-and-mortar bookstore. And except for your local user groups, there were no conferences, seminars, SQL Saturdays, or any online video hookups where you could interact with a person. You'd have to call Microsoft Support...on the phone...a LANDLINE phone.  And none of this "SQL Family" business!</Cranky Old Guy> Even now, with all these excellent resources available, it's still daunting for a beginner to seek help for SQL Server.  The product is roughly 1247.4523 times larger than it was 15 years ago, and it's simply impossible to know everything about it.*  So whether you are a beginner, or a seasoned pro of over a decade's experience, what do you do when you need help on SQL Server? That's so meta... In the spirit of offering help, here are some suggestions for your topic: Tell us about a person or SQL Server community who have been helpful to you.  It can be about a technical problem, or not, e.g. someone who volunteered for your local SQL Saturday.  Sing their praises!  Let the world know who they are! Do you have any tricks for using Books Online?  Do you use the locally installed product, or are you completely online with BOL/MSDN/Technet, and why? If you've been using SQL Server for over 10 years, how has your help-seeking changed? Are you using Twitter, StackOverflow, MSDN Forums, or another resource that didn't exist when you started? What made you switch? Do you spend more time helping others than seeking help? What motivates you to help, and how do you contribute? Structure your post along the lyrics to The Beatles song Help! Audio or video renditions are particularly welcome! Lyrics must include reference to SQL Server terminology or community, and performances must be in your voice or include you playing an instrument. These are just suggestions, you are free to write whatever you like.  Bonus points if you can incorporate ALL of these into a single post.  (Or you can do multiple posts, we're flexible like that.)  Help us help others by showing how others helped you! Legalese, Your Rights, Yada yada... If you would like to participate in T-SQL Tuesday please be sure to follow the rules below: Your blog post must be published between Tuesday, September 11, 2012 00:00:00 GMT and Wednesday, September 12, 2012 00:00:00 GMT. Include the T-SQL Tuesday logo (above) and hyperlink it back to this post. If you don’t see your post in trackbacks, add the link to the comments below. If you are on Twitter please tweet your blog using the #TSQL2sDay hashtag.  I can be contacted there as @sql_r, in case you have questions or problems with comments/trackback.  I'll have a follow-up post listing all the contributions as soon as I can. Thank you all for participating, and special thanks to Adam Machanic (b|t) for all his help and for continuing this series!

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• Knowing your user is key--Part 1: Motivation

  - by erikanollwebb

  I was thinking where the best place to start in this blog would be and finally came back to a theme that I think is pretty critical--successful gamification in the enterprise comes down to knowing your user.  Lots of folks will say that gamification is about understanding that everyone is a gamer.  But at least in my org, that argument won't play for a lot of people.  Pun intentional.  It's not that I don't see the attraction to the idea--really, very few people play no games at all.  If they don't play video games, they might play solitaire on their computer.  They may play card games, or some type of sport.  Mario Herger has some great facts on how much game playing there is going on at his Enterprise-Gamification.com website. But at the end of the day, I can't sell that into my organization well.  We are Oracle.  We make big, serious software designed run your whole business.  We don't make Angry Birds out of your financial reporting tools.  So I stick with the argument that works better.  Gamification techniques are really just good principals of user experience packaged a little differently.  Feedback?  We already know feedback is important when using software.  Progress indicators?  Got that too.  Game mechanics may package things in a more explicit way but it's not really "new".  To know how to use game mechanics, and what a user experience team is important for, is totally understanding who our users are and what they are motivated by. For several years, I taught college psychology courses, including Motivation.  Motivation is generally broken down into intrinsic and extrinsic motivation.  There's intrinsic, which comes from within the individual.  And there's extrinsic, which comes from outside the individual.  Intrinsic motivation is that motivation that comes from just a general sense of pleasure in the doing of something.  For example, I like to cook.  I like to cook a lot.  The kind of cooking I think is just fun makes other people--people who don't like to cook--cringe.  Like the cake I made this week--the star-spangled rhapsody from The Cake Bible: two layers of meringue, two layers of genoise flavored with a raspberry eau de vie syrup, whipped cream with berries and a mousseline buttercream, also flavored with raspberry liqueur and topped with fresh raspberries and blueberries. I love cooking--I ask for cooking tools for my birthday and Christmas, I take classes like sushi making and knife skills for fun.  I like reading about you can make an emulsion of egg yolks, melted butter and lemon, cook slowly and transform them into a sauce hollandaise (my use of all the egg yolks that didn't go into the aforementioned cake).  And while it's nice when people like what I cook, I don't do it for that.  I do it because I think it's fun.  My former boss, Ultan Ó Broin, loves to fish in the sea off the coast of Ireland.  Not because he gets prizes for it, or awards, but because it's fun.  To quote a note he sent me today when I asked if having been recently ill kept him from the beginning of mackerel season, he told me he had already been out and said "I can fish when on a deathbed" (read more of Ultan's work, see his blogs on User Assistance and Translation.). That's not the kind of intensity you get about something you don't like to do.  I'm sure you can think of something you do just because you like it. So how does that relate to gamification?  Gamification in the enterprise space is about uncovering the game within work.  Gamification is about tapping into things people already find motivating.  But to do that, you need to know what that user is motivated by. Customer Relationship Management (CRM) is one of those areas where over-the-top gamification seems to work (not to plug a competitor in this space, but you can search on what Bunchball* has done with a company just a little north of us on 101 for the CRM crowd).  Sales people are naturally competitive and thrive on that plus recognition of their sales work.  You can use lots of game mechanics like leaderboards and challenges and scorecards with this type of user and they love it.  Show my whole org I'm leading in sales for the quarter?  Bring it on!  However, take the average accountant and show how much general ledger activity they have done in the last week and expose it to their whole org on a leaderboard and I think you'd see a lot of people looking for a new job.  Why?  Because in general, accountants aren't extraverts who thrive on competition in their work.  That doesn't mean there aren't game mechanics that would work for them, but they won't be the same game mechanics that work for sales people.  It's a different type of user and they are motivated by different things. To break this up, I'll stop here and post now.  I'll pick this thread up in the next post. Thoughts? Questions? *Disclosure: To my knowledge, Oracle has no relationship with Bunchball at this point in time.

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• Think before you animate

  - by David Paquette

  Animations are becoming more and more common in our applications.  With technologies like WPF, Silverlight and jQuery, animations are becoming easier for developers to use (and abuse).  When used properly, animation can augment the user experience.  When used improperly, animation can degrade the user experience.  Sometimes, the differences can be very subtle. I have recently made use of animations in a few projects and I very quickly realized how easy it is to abuse animation techniques.  Here are a few things I have learned along the way. 1) Don’t animate for the sake of animating We’ve all seen the PowerPoint slides with annoying slide transitions that animate 20 different ways.  It’s distracting and tacky.  The same holds true for your application.  While animations are fun and becoming easy to implement, resist the urge to use the technology just because you think the technology is amazing.   2) Animations should (and do) have meaning I recently built a simple Windows Phone 7 (WP7) application, Steeped (download it here).  The application has 2 pages.  The first page lists a number of tea types.  When the user taps on one of the tea types, the application navigates to the second page with information about that tea type and some options for the user to choose from.       One of the last things I did before submitting Steeped to the marketplace was add a page transition between the 2 pages.  I choose the Slide / Fade Out transition.  When the user selects a tea type, the main page slides to the left and fades out.  At the same time, the details page slides in from the right and fades in.  I tested it and thought it looked great so I submitted the app.  A few days later, I asked a friend to try the app.  He selected a tea type, and I was a little surprised by how he used the app.  When he wanted to navigate back to the main page, instead of pressing the back button on the phone, he tried to use a swiping gesture.  Of course, the swiping gesture did nothing because I had not implemented that feature.  After thinking about it for a while, I realized that the page transition I had chosen implied a particular behaviour.  As a user, if an action I perform causes an item (in this case the page) to move, then my expectation is that I should be able to move it back.  I have since added logic to handle the swipe gesture and I think the app flows much better now. When using animation, it pays to ask yourself:  What story does this animation tell my users?   3) Watch the replay Some animations might seem great initially but can get annoying over time.  When you use an animation in your application, make sure you try using it over and over again to make sure it doesn’t get annoying.  When I add an animation, I try watch it at least 25 times in a row.  After watching the animation repeatedly, I can make a more informed decision whether or not I should keep the animation.  Often, I end up shortening the length of the animations.   4) Don’t get in the users way An animation should never slow the user down.  When implemented properly, an animation can give a perceived bump in performance.  A good example of this is a the page transitions in most of the built in apps on WP7.  Obviously, these page animations don’t make the phone any faster, but they do provide a more responsive user experience.  Why?  Because most of the animations begin as soon as the user has performed some action.  The destination page might not be fully loaded yet, but the system responded immediately to user action, giving the impression that the system is more responsive.  If the user did not see anything happen until after the destination page was fully loaded, the application would feel clumsy and slow.  Also, it is important to make sure the animation does not degrade the performance (or perceived performance) of the application.   Jut a few things to consider when using animations.  As is the case with many technologies, we often learn how to misuse it before we learn how to use it effectively.

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• Gamification = -10#/3mo

  - by erikanollwebb

  One of the purposes of gamification of anything is to see if you can modify the behavior of the user. In the enterprise, that might mean getting sales people to enter more information into a CRM system, encouraging employees to update their HR records, motivating people to participate in forums and discussions, or process invoices more quickly.  Wikipedia defines behavior modification as "the traditional term for the use of empirically demonstrated behavior change techniques to increase or decrease the frequency of behaviors, such as altering an individual's behaviors and reactions to stimuli through positive and negative reinforcement of adaptive behavior and/or the reduction of behavior through its extinction, punishment and/or satiation."  Gamification is just a way to modify someone's behavior using game mechanics. And the magic question is always whether it works. So I thought I would present my own little experiment from the last few months.  This spring, I upgraded to a Samsung Galaxy 4.  It's a pretty sweet phone in many ways, but one of the little extras I discovered was a built in app called S Health. S Health is an app that you can use to track calories, weight, exercise and it has a built in pedometer. I looked at it when I got the phone, but assumed you had to turn it on to use it so I didn't look at it much.  But sometime in July, I realized that in fact, it just ran in the background and was quietly tracking my steps, with a goal of 10,000 per day.  10,000 steps per day is this magic number recommended by the Surgeon General and the American Heart Association.  Dr. Oz pushes it as the goal for daily exercise.  It's about 5 miles of walking. I'm generally not the kind of person who always has my phone with me.  I leave it in my purse and pull it out when I need it.  But then I realized that meant I wasn't getting a good measure of my steps.  I decided to do a little experiment, and carry it with me as much as possible for a week.  That's when I discovered the gamification that changed my life over the last 3 months.  When I hit 10,000 steps, the app jingled out a little "success!" tune and I got a badge.  I was hooked.  I started carrying my phone.  I started making sure I had shoes I could walk in with me.  I started walking at lunch time, because I realized how often I sat at my desk for 8-10 hours every day without moving.  I started pestering my husband to walk with me after work because I hadn't hit my 10,000 yet, leading him at one point to say "I'm not as much a slave to that badge as you are!"  I started looking at parking lots differently.  Can't get a space up close?  No worries, just that many steps toward my 10,000.  I even tried to see if there was a second power user level at 15,000 or 20,000 (*sadly, no).  If I was close at the end of the day, I have done laps around my house until I got my badge.  I have walked around the block one more time to get my badge.  I have mentally chastised myself when I forgot to put my phone in my pocket because I don't know how many steps I got.  The badge below I got when my boss and I were in New York City and we walked around the block of our hotel just to watch the badge pop up. There are a bunch of tools out on the market now that have similar ideas for helping you to track your exercise, make it social.  There are apps (my favorite is still Zombies, Run!).  You could buy a FitBit or UP by Jawbone.   Interactive fitness makes the Expresso stationary bike with built in video games.  All designed to help you be more aware of your activity and keep you engaged and motivated.  And the idea is to help you change your behavior. I know someone who would spend extra time and work hard on the Expresso because he had built up strategies for how to kill the most dragons while he was riding to get more points.  When the machine broke down, he didn't ride a different bike because it just wasn't that interesting. But for me, just the simple jingle and badge have been all I needed.  I admit, I still giggle gleefully when I hear the tune sing out from my pocket. After a few weeks, I noticed I had dropped a few pounds.  Not a lot, just 2-3.  But then I was really hooked.  I started making a point both to eat a little less and hit 10,000 steps as much as I could.  I bemoaned that during the floods in Boulder, I wasn't hitting my 10,000 steps.  And now, a few months later, I'm almost 10 lbs lighter. All for 1 badge a day. So yes, simple gamification can increase motivation and engagement.  And that can lead to changes in behavior.  Now the job is to apply that to the enterprise space in a meaningful and engaging way. 

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• Proxied calls not working as expected

  - by AndyH

  I have been modifying an application to have a cleaner client/server split to allow for load splitting and resource sharing etc. Everything is written to an interface so it was easy to add a remoting layer to the interface using a proxy. Everything worked fine. The next phase was to add a caching layer to the interface and again this worked fine and speed was improved but not as much as I would have expected. On inspection it became very clear what was going on. I feel sure that this behavior has been seen many times before and there is probably a design pattern to solve the problem but it eludes me and I'm not even sure how to describe it. It is easiest explained with an example. Let's imagine the interface is interface IMyCode { List<IThing> getLots( List<String> ); IThing getOne( String id ); } The getLots() method calls getOne() and fills up the list before returning. The interface is implemented at the client which is proxied to a remoting client which then calls the remoting server which in turn calls the implementation at the server. At the client and the server layers there is also a cache. So we have :- Client interface | Client cache | Remote client | Remote server | Server cache | Server interface If we call getOne("A") at the client interface, the call is passed to the client cache which faults. This then calls the remote client which passes the call to the remote server. This then calls the server cache which also faults and so the call is eventually passed to the server interface which actually gets the IThing. In turn the server cache is filled and finally the client cache also. If getOne("A") is again called at the client interface the client cache has the data and it gets returned immediately. If a second client called getOne("B") it would fill the server cache with "B" as well as it's own client cache. Then, when the first client calls getOne("B") the client cache faults but the server cache has the data. This is all as one would expect and works well. Now lets call getLots( [ "C", "D" ] ). This works as you would expect by calling getOne() twice but there is a subtlety here. The call to getLots() cannot directly make use of the cache. Therefore the sequence is to call the client interface which in turn calls the remote client, then the remote server and eventually the server interface. This then calls getOne() to fill the list before returning. The problem is that the getOne() calls are being satisfied at the server when ideally they should be satisfied at the client. If you imagine that the client/server link is really slow then it becomes clear why the client call is more efficient than the server call once the client cache has the data. This example is contrived to illustrate the point. The more general problem is that you cannot just keep adding proxied layers to an interface and expect it to work as you would imagine. As soon as the call goes 'through' the proxy any subsequent calls are on the proxied side rather than 'self' side. Have I failed to learn or not learned something correctly? All this is implemented in Java and I haven't used EJBs. It seems that the example may be confusing. The problem is nothing to do with cache efficiencies. It is more to do with an illusion created by the use of proxies or AOP techniques in general. When you have an object whose class implements an interface there is an assumption that a call on that object might make further calls on that same object. For example, public String getInternalString() { return InetAddress.getLocalHost().toString(); } public String getString() { return getInternalString(); } If you get an object and call getString() the result depends where the code is running. If you add a remoting proxy to the class then the result could be different for calls to getString() and getInternalString() on the same object. This is because the initial call gets 'deproxied' before the actual method is called. I find this not only confusing but I wonder how I can control this behavior especially as the use of the proxy may be by a third party. The concept is fine but the practice is certainly not what I expected. Have I missed the point somewhere?

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• Understanding the 'High Performance' meaning in Extreme Transaction Processing

  - by kyap

  Despite my previous blogs entries on SOA/BPM and Identity Management, the domain where I'm the most passionated is definitely the Extreme Transaction Processing, commonly called XTP.I came across XTP back to 2007 while I was still FMW Product Manager in EMEA. At that time Oracle acquired a company called Tangosol, which owned an unique product called Coherence that we renamed to Oracle Coherence. Beside this innovative renaming of the product, to be honest, I didn't know much about it, except being a "distributed in-memory cache for Extreme Transaction Processing"... not very helpful still.In general when people doesn't fully understand a technology or a concept, they tend to find some shortcuts, either correct or not, to justify their lack-of understanding... and of course I was part of this category of individuals. And the shortcut was "Oracle Coherence Cache helps to improve Performance". Excellent marketing slogan... but not very meaningful still. By chance I was able to get away quickly from that group in July 2007* at Thames Valley Park (UK), after I attended one of the most interesting workshops, in my 10 years career in Oracle, delivered by Brian Oliver. The biggest mistake I made was to assume that performance improvement with Coherence was related to the response time. Which can be considered as legitimus at that time, because after-all caches help to reduce latency on cached data access, hence reduce the response-time. But like all caches, you need to define caching and expiration policies, thinking about the cache-missed strategy, and most of the time you have to re-write partially your application in order to work with the cache. At a result, the expected benefit vanishes... so, not very useful then?The key mistake I made was my perception or obsession on how performance improvement should be driven, but I strongly believe this is still a common problem to most of the developers. In fact we all know the that the performance of a system is generally presented by the Capacity (or Throughput), with the 2 important dimensions Speed (response-time) and Volume (load) :Capacity (TPS) = Volume (T) / Speed (S)To increase the Capacity, we can either reduce the Speed(in terms of response-time), or to increase the Volume. However we tend to only focus on reducing the Speed dimension, perhaps it is more concrete and tangible to measure, and nicer to present to our management because there's a direct impact onto the end-users experience. On the other hand, we assume the Volume can be addressed by the underlying hardware or software stack, so if we need more capacity (scale out), we just add more hardware or software. Unfortunately, the reality proves that IT is never as ideal as we assume...The challenge with Speed improvement approach is that it is generally difficult and costly to make things already fast... faster. And by adding Coherence will not necessarily help either. Even though we manage to do so, the Capacity can not increase forever because... the Speed can be influenced by the Volume. For all system, we always have a performance illustration as follow: In all traditional system, the increase of Volume (Transaction) will also increase the Speed (Response-Time) as some point. The reason is simple: most of the time the Application logics were not designed to scale. As an example, if you have a while-loop in your application, it is natural to conceive that parsing 200 entries will require double execution-time compared to 100 entries. If you need to "Speed-up" the execution, you can only upgrade your hardware (scale-up) with faster CPU and/or network to reduce network latency. It is technically limited and economically inefficient. And this is exactly where XTP and Coherence kick in. The primary objective of XTP is about designing applications which can scale-out for increasing the Volume, by applying coding techniques to keep the execution-time as constant as possible, independently of the number of runtime data being manipulated. It is actually not just about having an application running as fast as possible, but about having a much more predictable system, with constant response-time and linearly scale, so we can easily increase throughput by adding more hardwares in parallel. It is in general combined with the Low Latency Programming model, where we tried to optimize the network usage as much as possible, either from the programmatic angle (less network-hoops to complete a task), and/or from a hardware angle (faster network equipments). In this picture, Oracle Coherence can be considered as software-level XTP enabler, via the Distributed-Cache because it can guarantee: - Constant Data Objects access time, independently from the number of Objects and the Coherence Cluster size - Data Objects Distribution by Affinity for in-memory data grouping - In-place Data Processing for parallel executionTo summarize, Oracle Coherence is indeed useful to improve your application performance, just not in the way we commonly think. It's not about the Speed itself, but about the overall Capacity with Extreme Load while keeping consistant Speed. In the future I will keep adding new blog entries around this topic, with some sample codes experiences sharing that I capture in the last few years. In the meanwhile if you want to know more how Oracle Coherence, I strongly suggest you to start with checking how our worldwide customers are using Oracle Coherence first, then you can start playing with the product through our tutorial.Have Fun !

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• "Guiding" a Domain Expert to Retire from Programming

  - by James Kolpack

  I've got a friend who does IT at a local non-profit where they're using a custom web application which is no longer supported by the company who built it. (out of business, support was too expensive, I'm not sure...) Development on this app started around 10+ years ago so the technologies being harnessed are pretty out of date now - classic asp using vbscript and SQL Server 2000. The application domain is in the realm of government bookkeeping - so even though the development team is long gone, there are often new requirements of this software. Enter the... The domain expert. This is an middle aged accounting whiz without much (or any?) prior development experience. He studied the pages, code and queries and learned how to ape the style of the original team which, believe me, is mediocre at best. He's very clever and very tenacious but has no experience in software beyond what he's picked up from this app. Otherwise, he's a pleasant guy to talk to and definitely knows his domain. My friend in IT, and probably his superiors in the company, want him out of the code. They view him as wasting his expertise on coding tasks he shouldn't be doing. My friend got me involved with a few small contracts which I handled without much problem - other than somewhat of a communication barrier with the domain expert. He explained the requirements very quickly, assuming prior knowledge of the domain which I do not have. This is partially his normal style, and I think maybe a bit of resentment from my involvement. So, I think he feels like the owner of the code and has entrenched himself in a development position. So... his coding technique. One of his latest endeavors was to make a page that only he could reach (theoretically - the security model for the system is wretched) where he can enter a raw SQL query, run it, and save the query to run again later. A report that I worked on had been originally implemented by him using 6 distinct queries, 3 or 4 temp tables to coordinate the data between the queries, and the final result obtained by importing the data from the final query into Access and doing a pivot and some formatting. It worked - well, some of the results were incorrect - but at what a cost! (I implemented the report in a single query with at least 1/10th the amount of code.) He edits code in notepad. He doesn't seem to know about online reference material for the languages. I recently read an article on Dr. Dobbs titled "What Makes Bad Programmers Different" - and instantly thought of our domain expert. From the article: Their code is large, messy, and bug laden. They have very superficial knowledge of their problem domain and their tools. Their code has a lot of copy/paste and they have very little interest in techniques that reduce it. The fail to account for edge cases, while inefficiently dealing with the general case. They never have time to comment their code or break it into smaller pieces. Empirical evidence plays no little role in their decisions. 5.5 out of 6. My friend is wanting me to argue the case to their management - specifically, I got this email from their manager to respond to: ...Also, I need to talk to you about what effect there is from Domain Expert continuing to make edits to the live environment. If that is a problem for you I need to know so I can have his access blocked. Some examples would help. In my opinion, from a technical standpoint, it's dangerous to have him making changes without any oversight. On the other hand, I'm just doing one-off contracts at this point and don't have much desire to get involved deeply enough that I'm essentially arguing as one of the Bobs from Office Space. I'd like to help my friend out - but I feel like I'm getting in the middle of a political battle. More importantly - if I do get involved and suggest that his editing privileges be removed, it needs to be handled carefully so that doesn't feel belittled. He is beyond a doubt the foremost expert on this system. I'm hoping this is familiar territory for some other stackechangers, because I'm feeling a little bewildered. How should I respond? Should I argue that he shouldn't be allowed to touch the code? Should I phrase it as "no single developer, no matter how experienced, should be working on production code unchecked"? Should I argue to keep him involved with the code, but with a review process? Should I say "glad I could help, but uh, I'm busy now!" Other options? Thanks a bunch!

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• UK OUG Conference Highlights and Insights

  - by Richard Bingham

  As per my preemptive post, this was the first time the annual conference organized by the UK Oracle User Group (UKOUG) was split into two events, one for Oracle Applications and another in December for Oracle Technology. Apps13, as it was branded, was hailed as a success, with over 1000 registered attendees and three days of sessions, exhibition, round-tables and many other types of content. As this poster on their stand illustrates, the UKOUG is a strong community with popular participants from both big and small Oracle partners and customers. The venue was a more intimate setting than previous years also, allowing everyone to casually bump into those they hoped to. It gave a real feeling of an Apps Community. The main themes over the days where CRM and Customer Experience, HCM, and FIN/SCM. This allowed people to attend just one focused day if they wanted. In addition the Apps Transformation stream ran across all three days, offering insights, advice, and details on the newer product solutions like Fusion Applications.  Here are some of the key take-aways I got from the conference, specific to my role in Fusion Applications Developer Relations: User Experience continues to be a significant reason for adopting some of the newer application products available, with immediately obvious gains in user productivity and satisfaction reported by customers. Also this doesn't stop with the baked-in UX either, with their Design Patterns proving popular and indeed currently being extended to including things like extending on ADF mobile and customizing the Simplified UI. More on this to come from us soon. The executive sessions emphasized the "it's a journey" phrase, illustrating that modern business applications are powered by technologies such as Cloud, Mobile, Social and Big Data and these can be harnessed to help propel your organization forward. Indeed the emphasis is away from the traditional vendor prescribed linear applications road map, and towards plotting a course based on business priorities supported by a broad range of integrated solutions. To help with this several conference sessions demoed the new "Applications Navigator" tool, developed in partnership with OUG members, which offers a visual framework to help organizations plan their Oracle Applications investments around business and technology imperatives. Initial reaction was positive, especially as customers do not need to decipher Oracle's huge product catalog and embeds the best blend of proven and integrated applications solutions. We'll share more on this when it is generally available. Several sessions focused around explanations and interpretation of Oracle OpenWorld 2013, helping highlight the key Oracle Applications messages and directions. With a relative small percentage of conference attendees also at OpenWorld (from a show of hands) this was a popular way to distill the information available down into specific items of interest for the community. Please note the original OpenWorld 2013 content is still available for download but will not remain available forever (via the Oracle website OpenWorld Content Catalog > pick a session > see the PDF download). With the release of E-Business Suite 12.2 the move to develop and deploy on the Fusion Middleware stack becomes a reality for many Oracle Applications customers. This coupled with recent E-Business Suite features such as the Integrated SOA Gateway and the E-Business Suite SDK for Java, illustrates how the gap between the technologies and techniques involved in extending E-Business Suite and Fusion Applications is quickly narrowing. We'll see this merging continue to evolve going forwards. Getting started with Oracle Cloud Applications is actually easier than many customers expected, with a broad selection of both large and medium sized organizations explaining how they added new features to their existing Oracle Applications portfolios. New functionality available from Fusion HCM and CX are popular extensions that do not have to disrupt those core business services. Coexistence is the buzzword here, and the available integration is also simpler than many expected, commonly involving an initial setup data load, then regularly incremental synchronizations, often without a need for real-time constant communication between systems. With much of this pre-built already the implementation process is also quite rapid. With most people dressed in suits, we wanted to get the conversations going without the traditional english reserve, so we decided to make ourselves a bit more obvious, as the photo below shows. This seemed to be quite successful and helped those interested identify and approach us. Keep a look out for similar again. In fact if you're in the UK there is an "Apps Transformation Day" planned by the UKOUG for the 19th March 2014, with more details to follow. Again something we'll be sure to participate in. I am hoping to attend the next half of the UKOUG annual conference, Tech13, that focuses more on Oracle technology and where there is more likely to be larger attendance of those interested in the lower-level aspects of applications customization and development. If you're going, let me know and maybe we can meet up.

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• Styling ASP.NET MVC Error Messages

  - by MightyZot

  Originally posted on: http://geekswithblogs.net/MightyZot/archive/2013/11/11/styling-asp.net-mvc-error-messages.aspxOff the cuff, it may look like you’re stuck with the presentation of your error messages (model errors) in ASP.NET MVC. That’s not the case, though. You actually have quite a number of options with regard to styling those boogers. Like many of the helpers in MVC, the Html.ValidationMessageFor helper has multiple prototypes. One of those prototypes lets you pass a dictionary, or anonymous object, representing attribute values for the resulting markup. @Html.ValidationMessageFor( m => Model.Whatever, null, new { @class = “my-error” }) By passing the htmlAttributes parameter, which is the last parameter in the call to the prototype of Html.ValidationMessageFor shown above, I can style the resulting markup by associating styles to the my-error css class.  When you run your MVC project and view the source, you’ll notice that MVC adds the class field-validation-valid or field-validation-error to a span created by the helper. You could actually just style those classes instead of adding your own…it’s really up to you. Now, what if you wanted to move that error message around? Maybe you want to put that error message in a box or a callout. How do you do that? When I first started using MVC, it didn’t occur to me that the Html.ValidationMessageFor helper just spits out a little bit of markup. I wanted to put the error messages in boxes with white backgrounds, our site originally had a black background, and show a little nib on the side to make them look like callouts or conversation bubbles. Not realizing how much freedom there is in the styling and markup, and after reading someone else’s post, I created my own version of the ValidationMessageFor helper that took out the span and replaced it with divs. I styled the divs to produce the effect of a popup box and had a lot of trouble with sizing and such. That’s a really silly and unnecessary way to solve this problem. If you want to move your error messages around, all you have to do is move the helper. MVC doesn’t appear to care where you put it, which makes total sense when you think about it. Html.ValidationMessageFor is just spitting out a little markup using a little bit of reflection on the name you’re passing it. All you’ve got to do to style it the way you want it is to put it in whatever markup you desire. Take a look at this, for example… <div class=”my-anchor”>@Html.ValidationMessageFor( m => Model.Whatever )</div> @Html.TextBoxFor(m => Model.Whatever) Now, given that bit of HTML, consider the following CSS… <style> .my-anchor { position:relative; } .field-validation-error {    background-color:white;    border-radius:4px;    border: solid 1px #333;    display: block;    position: absolute;    top:0; right:0; left:0;    text-align:right; } </style> The my-anchor class establishes an anchor for the absolutely positioned error message. Now you can move the error message wherever you want it relative to the anchor. Using css3, there are some other tricks. For example, you can use the :not(:empty) selector to select the span and apply styles based upon whether or not the span has text in it. Keep it simple, though. Moving your elements around using absolute positioning may cause you issues on devices with screens smaller than your standard laptop or PC. While looking for something else recently, I saw someone asking how to style the output for Html.ValidationSummary.  Html.ValidationSummery is the helper that will spit out a list of property errors, general model errors, or both. Html.ValidationSummary spits out fairly simple markup as well, so you can use the techniques described above with it also. The resulting markup is a <ul><li></li></ul> unordered list of error messages that carries the class validation-summary-errors In the forum question, the user was asking how to hide the error summary when there are no errors. Their errors were in a red box and they didn’t want to show an empty red box when there aren’t any errors. Obviously, you can use the css3 selectors to apply different styles to the list when it’s empty and when it’s not empty; however, that’s not support in all browsers. Well, it just so happens that the unordered list carries the style validation-summary-valid when the list is empty. While the div rendered by the Html.ValidationSummary helper renders a visible div, containing one invisible listitem, you can always just style the whole div with “display:none” when the validation-summary-valid class is applied and make it visible when the validation-summary-errors class is applied. Or, if you don’t like that solution, which I like quite well, you can also check the model state for errors with something like this… int errors = ViewData.ModelState.Sum(ms => ms.Value.Errors.Count); That’ll give you a count of the errors that have been added to ModelState. You can check that and conditionally include markup in your page if you want to. The choice is yours. Obviously, doing most everything you can with styles increases the flexibility of the presentation of your solution, so I recommend going that route when you can. That picture of the fat guy jumping has nothing to do with the article. That’s just a picture of me on the roof and I thought it was funny. Doesn’t every post need a picture?

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• Getting Started with ADF Mobile Sample Apps

  - by Denis T

  Getting Started with ADF Mobile Sample Apps   Installation Steps Install JDeveloper 11.1.2.3.0 from Oracle Technology Network After installing JDeveloper, go to Help menu and select "Check For Updates" and find the ADF Mobile extension and install this. It will require you restart JDeveloper For iOS development, be on a Mac and have Xcode installed. (Currently only Xcode 4.4 is officially supported. Xcode 4.5 support is coming soon) For Android development, have the Android SDK installed. In the JDeveloper Tools menu, select "Preferences". In the Preferences dialog, select ADF Mobile. You can expand it to select configure your Platform preferences for things like the location of Xcode and the Android SDK. In your /jdeveloper/jdev/extensions/oracle.adf.mobile/Samples folder you will find a PublicSamples.zip. Unzip this into the Samples folder so you have all the projects ready to go. Open each of the sample application's .JWS file to open the corresponding workspace. Then from the "Application" menu, select "Deploy" and then select the deployment profile for the platform you wish to deploy to. Try deploying to the simulator/emulator on each platform first because it won't require signing. Note: If you wish to deploy to the Android emulator, it must be running before you start the deployment.   Sample Application Details   Recommended Order of Use Application Name Description 1 HelloWorld The "hello world" application for ADF Mobile, which demonstrates the basic structure of the framework. This basic application has a single application feature that is implemented with a local HTML file. Use this application to ascertain that the development environment is set up correctly to compile and deploy an application. See also Section 4.2.2, "What Happens When You Create an ADF Mobile Application." 2 CompGallery This application is meant to be a runtime application and not necessarily to review the code, though that is available. It serves as an introduction to the ADF Mobile AMX UI components by demonstrating all of these components. Using this application, you can change the attributes of these components at runtime and see the effects of those changes in real time without recompiling and redeploying the application after each change. See generally Chapter 8, "Creating ADF Mobile AMX User Interface." 3 LayoutDemo This application demonstrates the user interface layout and shows how to create the various list and button styles that are commonly used in mobile applications. It also demonstrates how to create the action sheet style of a popup component and how to use various chart and gauge components. See Section 8.3, "Creating and Using UI Components" and Section 8.5, "Providing Data Visualization." Note: This application must be opened from the Samples directory or the Default springboard option must be cleared in the Applications page of the adfmf-application.xml overview editor, then selected again. 4 JavaDemo This application demonstrates how to bind the user interface to Java beans. It also demonstrates how to invoke EL bindings from the Java layer using the supplied utility classes. See also Section 8.10, "Using Event Listeners" and Section 9.2, "Understanding EL Support." 5 Navigation This application demonstrates the various navigation techniques in ADF Mobile, including bounded task flows and routers. It also demonstrates the various page transitions. See also Section 7.2, "Creating Task Flows." Note: This application must be opened from the Samples directory or the Default springboard option must be cleared in the Applications page of the adfmf-application.xml overview editor, then selected again. 6 LifecycleEvents This application implements lifecycle event handlers on the ADF Mobile application itself and its embedded application features. This application shows you where to insert code to enable the applications to perform their own logic at certain points in the lifecycle. See also Section 5.6, "About Lifecycle Event Listeners." Note: iOS, the LifecycleEvents sample application logs data to the Console application, located at Applications-Utilities-Console application. 7 DeviceDemo This application shows you how to use the DeviceFeatures data control to expose such device features as geolocation, e-mail, SMS, and contacts, as well as how to query the device for its properties. See also Section 9.5, "Using the DeviceFeatures Data Control." Note: You must also run this application on an actual device because SMS and some of the device properties do not function on an iOS simulator or Android emulator. 8 GestureDemo This application demonstrates how gestures can be implemented and used in ADF Mobile applications. See also Section 8.4, "Enabling Gestures." 9 StockTracker This application demonstrates how data change events use Java to enable data changes to be reflected in the user interface. It also has a variety of layout use cases, gestures and basic mobile patterns. See also Section 9.7, "Data Change Events."

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• Plagued by multithreaded bugs

  - by koncurrency

  On my new team that I manage, the majority of our code is platform, TCP socket, and http networking code. All C++. Most of it originated from other developers that have left the team. The current developers on the team are very smart, but mostly junior in terms of experience. Our biggest problem: multi-threaded concurrency bugs. Most of our class libraries are written to be asynchronous by use of some thread pool classes. Methods on the class libraries often enqueue long running taks onto the thread pool from one thread and then the callback methods of that class get invoked on a different thread. As a result, we have a lot of edge case bugs involving incorrect threading assumptions. This results in subtle bugs that go beyond just having critical sections and locks to guard against concurrency issues. What makes these problems even harder is that the attempts to fix are often incorrect. Some mistakes I've observed the team attempting (or within the legacy code itself) includes something like the following: Common mistake #1 - Fixing concurrency issue by just put a lock around the shared data, but forgetting about what happens when methods don't get called in an expected order. Here's a very simple example: void Foo::OnHttpRequestComplete(statuscode status) { m_pBar->DoSomethingImportant(status); } void Foo::Shutdown() { m_pBar->Cleanup(); delete m_pBar; m_pBar=nullptr; } So now we have a bug in which Shutdown could get called while OnHttpNetworkRequestComplete is occuring on. A tester finds the bug, captures the crash dump, and assigns the bug to a developer. He in turn fixes the bug like this. void Foo::OnHttpRequestComplete(statuscode status) { AutoLock lock(m_cs); m_pBar->DoSomethingImportant(status); } void Foo::Shutdown() { AutoLock lock(m_cs); m_pBar->Cleanup(); delete m_pBar; m_pBar=nullptr; } The above fix looks good until you realize there's an even more subtle edge case. What happens if Shutdown gets called before OnHttpRequestComplete gets called back? The real world examples my team has are even more complex, and the edge cases are even harder to spot during the code review process. Common Mistake #2 - fixing deadlock issues by blindly exiting the lock, wait for the other thread to finish, then re-enter the lock - but without handling the case that the object just got updated by the other thread! Common Mistake #3 - Even though the objects are reference counted, the shutdown sequence "releases" it's pointer. But forgets to wait for the thread that is still running to release it's instance. As such, components are shutdown cleanly, then spurious or late callbacks are invoked on an object in an state not expecting any more calls. There are other edge cases, but the bottom line is this: Multithreaded programming is just plain hard, even for smart people. As I catch these mistakes, I spend time discussing the errors with each developer on developing a more appropriate fix. But I suspect they are often confused on how to solve each issue because of the enormous amount of legacy code that the "right" fix will involve touching. We're going to be shipping soon, and I'm sure the patches we're applying will hold for the upcoming release. Afterwards, we're going to have some time to improve the code base and refactor where needed. We won't have time to just re-write everything. And the majority of the code isn't all that bad. But I'm looking to refactor code such that threading issues can be avoided altogether. One approach I am considering is this. For each significant platform feature, have a dedicated single thread where all events and network callbacks get marshalled onto. Similar to COM apartment threading in Windows with use of a message loop. Long blocking operations could still get dispatched to a work pool thread, but the completion callback is invoked on on the component's thread. Components could possibly even share the same thread. Then all the class libraries running inside the thread can be written under the assumption of a single threaded world. Before I go down that path, I am also very interested if there are other standard techniques or design patterns for dealing with multithreaded issues. And I have to emphasize - something beyond a book that describes the basics of mutexes and semaphores. What do you think? I am also interested in any other approaches to take towards a refactoring process. Including any of the following: Literature or papers on design patterns around threads. Something beyond an introduction to mutexes and semaphores. We don't need massive parallelism either, just ways to design an object model so as to handle asynchronous events from other threads correctly. Ways to diagram the threading of various components, so that it will be easy to study and evolve solutions for. (That is, a UML equivalent for discussing threads across objects and classes) Educating your development team on the issues with multithreaded code. What would you do?

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• How to configure Hudson and git plugin with an SSH key

  - by jlpp

  I've got Hudson (continuous integration system) with the git plugin running on a Tomcat Windows Service. msysgit is installed and the msysgit bin dir is in the path. PuTTY/Pageant/plink are installed and msysgit is configured to use them. When I run a job that attempts to clone the git repository I get the following error: $ git clone -o origin git@hostname:project.git "e:\HUDSON_HOME\jobs\Project Trunk\workspace" ERROR: Error cloning remote repo 'origin' : Could not clone git@hostname:project.git ERROR: Cause: Error performing git clone -o origin git@hostname:project.git e:\HUDSON_HOME\jobs\Project Trunk\workspace Trying next repository ERROR: Could not clone from a repository FATAL: Could not clone hudson.plugins.git.GitException: Could not clone Running git clone -o origin git@hostname:project.git "e:\HUDSON_HOME\jobs\Project Trunk\workspace" from the command line works without error. I've confirmed that my issue is not the same as http://stackoverflow.com/questions/1177292/hudson-git-clone-error because git is in the path and I don't get any error about the git executable on Hudson's Configure System page. This leads me to believe that the problem is that the user who owns the Tomcat/Hudson Windows service (Local System) has no SSH key set up to be able to clone the git repository. My question is, how can I set things up so that the git plugin/msysgit know to use a particular SSH key when trying to clone? I don't think Pageant will work because the Tomcat service is running as the "Local System" user, but I may be wrong. I have tried setting Pageant up as a service (using runassvc.exe), passing the appropriate key, and having it run as "Local System". The Tomcat/Hudson service doesn't seem to be able to see the key from the pageant service. Are there any other techniques for setting up a key? Thanks. EDIT: The discussion on http://n4.nabble.com/Hudson-with-git-and-ssh-td375633.html shows that someone else had a similar question. ssh-agent was suggested and this tool does come with msysgit but I'm not sure how to use it in conjunction with the Hudson service. Still, good clue if anyone can fill in the gaps. Thanks to Peter for the comment with the link. Also, the discussion on http://n4.nabble.com/questions-about-git-and-github-plug-ins-td383420.html starts off with the same question. I'm trying to resurrect that thread.

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• Best ASP.NET E-Commerce Framework (aspDotNetStoreFront, AbleCommerce, BVCommerce, MediaChase,...)

  - by EfficionDave

  I need a full-featured asp.net E-Commerce solution for a project. It needs to be easily extensible as I need to extend it to integrate with a custom Flash based personalization engine. It should also have a great administrative back-end that handles inventory tracking, report, labels, shipping, ... so that the client can really use it as the basis for their business. I've used quite a few different E-Commerce systems including OSCommerce, Zen Cart, Catalook, and eTailer. While I was impressed with Zen Cart and eTailer, this project is big enough that I want to try a more serious, commercial offering. I'm particularly interested in thoughts on aspdotnetstorefront, BVCommerce, AbleCommerce, and MediaChase. [UPDATE] I've done quite a bit of evaluation since I posted this question and will give some of my findings below: BVCommerce - The price point is nice, the product seems fairly well regarded, and I've heard good things about customizing/extending it, it just doesn't seem like it's going to meet my needs as an Top Tier ECommerce solution. After viewing the tutorial videos, the Admin interface just seems too basic and outdated. aspDotNetStorefront - The integration with DotNetNuke was it's biggest selling point for me but after reading peoples opinions, it's integration seems quite weak. It's sounds like there's a significant learning curve and the architecture just doesn't sound like it's as clean as it should be. AbleCommerce - After a rather thorough evaluation, I have selected AbleCommerce for at least my next project. The Admin interface is beautiful and has a nice list of features. The E-Commerce portion of the user side is very well done, highly skin-able (using Master Pages and a couple other techniques), and the checkout workflow has all the features I need while still being very clean. Source to the API can be bought for $500 but you generally won't need it. There are some 3rd party modules available but there's not currently a large market for these. The biggest glaring weakness of AbleCommerce I've found is their CMS capabilities are very limited and not at all well suited for a non-technical user to make most site content updates. But I have a good solution for that that I plan adapting into AbleCommerce. They will automatically generate a site for you to play with to your heart's content for 30 days. It is defniitely worth checking out.

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• Detecting 'stealth' web-crawlers

  - by Jacco

  What options are there to detect web-crawlers that do not want to be detected? (I know that listing detection techniques will allow the smart stealth-crawler programmer to make a better spider, but I do not think that we will ever be able to block smart stealth-crawlers anyway, only the ones that make mistakes.) I'm not talking about the nice crawlers such as googlebot and Yahoo! Slurp. I consider a bot nice if it: identifies itself as a bot in the user agent string reads robots.txt (and obeys it) I'm talking about the bad crawlers, hiding behind common user agents, using my bandwidth and never giving me anything in return. There are some trapdoors that can be constructed updated list (thanks Chris, gs): Adding a directory only listed (marked as disallow) in the robots.txt, Adding invisible links (possibly marked as rel="nofollow"?), style="display: none;" on link or parent container placed underneath another element with higher z-index detect who doesn't understand CaPiTaLiSaTioN, detect who tries to post replies but always fail the Captcha. detect GET requests to POST-only resources detect interval between requests detect order of pages requested detect who (consistently) requests https resources over http detect who does not request image file (this in combination with a list of user-agents of known image capable browsers works surprisingly nice) Some traps would be triggered by both 'good' and 'bad' bots. you could combine those with a whitelist: It trigger a trap It request robots.txt? It doest not trigger another trap because it obeyed robots.txt One other important thing here is: Please consider blind people using a screen readers: give people a way to contact you, or solve a (non-image) Captcha to continue browsing. What methods are there to automatically detect the web crawlers trying to mask themselves as normal human visitors. Update The question is not: How do I catch every crawler. The question is: How can I maximize the chance of detecting a crawler. Some spiders are really good, and actually parse and understand html, xhtml, css javascript, VB script etc... I have no illusions: I won't be able to beat them. You would however be surprised how stupid some crawlers are. With the best example of stupidity (in my opinion) being: cast all URLs to lower case before requesting them. And then there is a whole bunch of crawlers that are just 'not good enough' to avoid the various trapdoors.

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• List of freely available programming books

  - by Karan Bhangui

  I'm trying to amass a list of programming books with opensource licenses, like Creative Commons, GPL, etc. The books can be about a particular programming language or about computers in general. Hoping you guys could help: Languages BASH Advanced Bash-Scripting Guide (An in-depth exploration of the art of shell scripting) C The C book C++ Thinking in C++ C++ Annotations How to Think Like a Computer Scientist C# .NET Book Zero: What the C or C++ Programmer Needs to Know About C# and the .NET Framework Illustrated C# 2008 (Dead Link) Data Structures and Algorithms with Object-Oriented Design Patterns in C# Threading in C# Common Lisp Practical Common Lisp On Lisp Java Thinking in Java How to Think Like a Computer Scientist Java Thin-Client Programming JavaScript Eloquent JavaScript Haskell Real world Haskell Learn You a Haskell for Great Good! Objective-C The Objective-C Programming Language Perl Extreme Perl (license not specified - home page is saying "freely available") The Mason Book (Open Publication License) Practical mod_perl (CreativeCommons Attribution Share-Alike License) Higher-Order Perl Learning Perl the Hard Way PHP Practical PHP Programming Zend Framework: Survive the Deep End PowerShell Mastering PowerShell Prolog Building Expert Systems in Prolog Adventure in Prolog Prolog Programming A First Course Logic, Programming and Prolog (2ed) Introduction to Prolog for Mathematicians Learn Prolog Now! Natural Language Processing Techniques in Prolog Python Dive Into Python Dive Into Python 3 How to Think Like a Computer Scientist A Byte of Python Python for Fun Invent Your Own Computer Games With Python Ruby Why's (Poignant) Guide to Ruby Programming Ruby - The Pragmatic Programmer's Guide Mr. Neighborly's Humble Little Ruby Book SQL Practical PostgreSQL x86 assembly Paul Carter's tutorial Lua Programming In Lua (for v5 but still largely relevant) Algorithms and Data Structures Algorithms Data Structures and Algorithms with Object-Oriented Design Patterns in Java Planning Algorithms Frameworks/Projects The Django Book The Pylons Book Introduction to Design Patterns in C++ with Qt 4 (Open Publication License) Version control The SVN Book Mercurial: The Definitive Guide Pro Git UNIX / Linux The Art of Unix Programming Linux Device Drivers, Third Edition Others Structure and Interpretation of Computer Programs The Little Book of Semaphores Mathematical Logic - an Introduction An Introduction to the Theory of Computation Developers Developers Developers Developers Linkers and loaders Beej's Guide to Network Programming Maven: The Definitive Guide I will expand on this list as I get comments or when I think of more :D Related: Programming texts and reference material for my Kindle What are some good free programming books? Can anyone recommend a free software engineering book? Edit: Oh I didn't notice the community wiki feature. Feel free to edit your suggestions right in!

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• Revisiting .NET, but what should I focus on?

  - by Wayne M

  After about a two-year hiatus, I'm brushing up on my .NET skills to find a .NET job (my previous two positions have very little development, or development using legacy technologies, so apart from a few very minor apps I have not touched .NET in close to two years). I'm aware of things like ASP.NET MVC, and I have previously read on things like NHibernate and DI/IOC, albeit I have yet to use them apart from very trivial "Hello World" type applications. I have a subscription to Rob Conery's Tekpub website and occasionally watch these videos when I have free time. My concern is this: I don't live in a very technical area. I would be surprised if any but the most tech-savvy companies have heard of, let alone use, ASP.NET MVC, NHibernate (or even LINQ/EF), or know about IoC. I would be willing to bet a large sum of money that 95% of the possible jobs I could obtain will use the following: Visual Source Safe, if any VCS at all ASP.NET 2.0 Webforms (3.5 if lucky) Raw ADO.NET on top of a very thin implementation of the Gateway pattern Stored Procedures in the database for most CRUD operations Gratuitous use of code-behind, with a Service layer if I'm lucky If I were extremely lucky, I might find a shop that has heard of ORMs and either uses one, or has wrote their own data abstraction. Also if I were lucky, the company would be using Model-View-Presenter. In light of this I'm not sure what I should focus on learning. Personally, I would prefer to be using the latest stuff - ASP.NET MVC, NHibernate, jQuery, WCF etc. Reality says I should go back to the basics, since it looks like most potential opportunities aren't going to be anywhere near the cutting edge, or anywhere close to it. And, as much as I would like to find a position and start to show the other developers the benefits, in my past experience this has usually resulted in my being fired for "not being a team player" and doing things the bad old way. So, I am curious how you would approach a situation like this? What should I focus on, in order to A) Reaquaint myself with .NET, and B) Prepare myself to obtain a .NET job again that is more than likely going to use techniques that I and most other knowledgeable developers will scoff at?

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• What is in your Mathematica tool bag?

  - by Timo

  We all know that Mathematica is great, but it also often lacks critical functionality. What kind of external packages / tools / resources do you use with Mathematica? I'll edit (and invite anyone else to do so too) this main post to include resources which are focused on general applicability in scientific research and which as many people as possible will find useful. Feel free to contribute anything, even small code snippets (as I did below for a timing routine). Also, undocumented and useful features in Mathematica 7 and beyond you found yourself, or dug up from some paper/site are most welcome. Please include a short description or comment on why something is great or what utility it provides. If you link to books on Amazon with affiliate links please mention it, e.g., by putting your name after the link. Packages: LevelScheme is a package that greatly expands Mathematica's capability to produce good looking plots. I use it if not for anything else then for the much, much improved control over frame/axes ticks. David Park's Presentation Package ($50 - no charge for updates) Tools: MASH is Daniel Reeves's excellent perl script essentially providing scripting support for Mathematica 7. (This is finally built in as of Mathematica 8 with the -script option.) Resources: Wolfram's own repository MathSource has a lot of useful if narrow notebooks for various applications. Also check out the other sections such as Current Documentation, Courseware for lectures, and Demos for, well, demos. Books: Mathematica programming: an advanced introduction by Leonid Shifrin (web, pdf) is a must read if you want to do anything more than For loops in Mathematica. Quantum Methods with Mathematica by James F. Feagin (amazon) The Mathematica Book by Stephen Wolfram (amazon) (web) Schaum's Outline (amazon) Mathematica in Action by Stan Wagon (amazon) - 600 pages of neat examples and goes up to Mathematica version 7. Visualization techniques are especially good, you can see some of them on the author's Demonstrations Page. Mathematica Programming Fundamentals by Richard Gaylord (pdf) - A good concise introduction to most of what you need to know about Mathematica programming. Undocumented (or scarcely documented) Features: How to customize Mathematica keyboard shortcuts. See this question. How to inspect patterns and functions used by Mathematica's own functions. See this answer How to achieve Consistent size for GraphPlots in Mathematica? See this question.

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• CSS layout mystery

  - by selfthinker

  Among the many two (or three) column layout techniques I sometimes use the following one: <div class="variant1"> <div class="left1"> <div class="left2"> left main content </div> </div> <div class="right1"> <div class="right2"> right sidebar </div> </div> </div> together with: .variant1 .left1 { float: left; margin-right: -200px; width: 100%; } .variant1 .left1 .left2 { margin-right: 200px; } .variant1 .right1 { float: right; width: 200px; } This works in all major browsers. But for some very strange reason exactly the same technique but reversed doesn't work: <div class="variant2"> <div class="left1"> <div class="left2"> left main content </div> </div> <div class="right1"> <div class="right2"> right sidebar </div> </div> </div> with .variant2 .left1 { float: left; width: 200px; } .variant2 .right1 { float: right; margin-left: -200px; width: 100%; } .variant2 .right1 .right2 { margin-left: 200px; } In the second variant all text in the sidebar cannot be selected and all links cannot be clicked. This is at least true for Firefox and Chrome. In IE7 the links can at least be clicked and Opera seems completely fine. Does anyone know the reason for this strange behaviour? Is it a browser bug? Please note: I am not looking for a working two column CSS layout technique, I know there are loads of them. And I don't necessarily need this technique to work. I only like to understand the reason why the second variant behaves like it does. Here is a link to a small test page which should illustrate the problem: http://selfthinker.org/stuff/css_layout_mystery.html

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