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  • JRuby Slick CanvasGameContainer using too much heap memory

    - by Jwosty
    I'm using Java's Slick library (great, by the way) just fine from JRuby. To start a game, I use AppGameContainer which works completely fine and as expected, but if I try to use CanvasGameContainer instead (I want a resizable window and Slick uses an old version of LWJGL that doesn't support this directly) it throws this error: Fri Jun 01 10:22:07 MDT 2012 INFO:Slick Build #274 Error: Your application used more stack memory than the safety cap of 2048K. Specify -J-Xss####k to increase it (#### = cap size in KB). Specify -w for full StackOverflowError stack trace I've tried increasing the heap size until my computer can't allocate any more memory, but to no avail. The CanvasGameContainer uses an awt window to display, which is resizable. Any ideas on why this is happening and/or how to fix this?

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  • Spinlocks, How Much Useful Are They?

    - by unknown
    How often do you find yourself actually using spinlocks in your code? How common is it to come across a situation where using a busy loop actually outperforms the usage of locks? Personally, when I write some sort of code that requires thread safety, I tend to benchmark it with different synchronization primitives, and as far as it goes, it seems like using locks gives better performance than using spinlocks. No matter for how little time I actually hold the lock, the amount of contention I receive when using spinlocks is far greater than the amount I get from using locks (of course, I run my tests on a multiprocessor machine). I realize that it's more likely to come across a spinlock in "low-level" code, but I'm interested to know whether you find it useful in even a more high-level kind of programming?

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  • Is writing a reference atomic on 64bit VMs

    - by Steffen Heil
    Hi The java memory model mandates that writing a int is atomic: That is, if you write a value to it (consisting of 4 bytes) in one thread and read it in another, you will get all bytes or none, but never 2 new bytes and 2 old bytes or such. This is not guaranteed for long. Here, writing 0x1122334455667788 to a variable holding 0 before could result in another thread reading 0x112233440000000 or 0x0000000055667788. Now the specification does not mandate object references to be either int or long-sized. For type safety reasons I suspect they are guaranteed to be written atomiacally, but on a 64bit VM these references could be very well 64bit values (merely memory addresses). No here are my question: Are there any memory model specs covering this (that I haven't found)? Are long-writes suspect to be atomic on 64bit VMs? Are VMs forced to map references to 32bit? Regards, Steffen

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  • Edit form not being instantiated

    - by 47
    I have two models like this: class OptionsAndFeatures(models.Model): options = models.TextField(blank=True, null=True) entertainment = models.TextField(blank=True, null=True) seats_trim = models.TextField(blank=True, null=True) convenience = models.TextField(blank=True, null=True) body_exterior = models.TextField(blank=True, null=True) lighting = models.TextField(blank=True, null=True) safety = models.TextField(blank=True, null=True) powertrain = models.TextField(blank=True, null=True) suspension_handling = models.TextField(blank=True, null=True) specs_dimensions = models.TextField(blank=True, null=True) offroad_capability = models.TextField(blank=True, null=True) class Vehicle(models.Model): ... options_and_features = models.ForeignKey(OptionsAndFeatures, blank=True, null=True) I have a model form for the OptionsAndFeaturesclass that I'm using in both the add and edit views. In the add view it works just fine. But the edit view renders the OptionsAndFeatures as blank. The code for the edit view is as follows: def edit_vehicle(request, stock_number=None): vehicle = get_object_or_404(Vehicle, stock_number=stock_number) if request.method == 'POST': # save info else: vehicle_form = VehicleForm(instance=vehicle) photos = PhotosFormSet(instance=vehicle) options = OptionsForm(instance=vehicle) #render_to_reponse What could be the problem here?

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  • Design for complex ATG applications

    - by Glen Borkowski
    Overview Needless to say, some ATG applications are more complex than others.  Some ATG applications support a single site, single language, single catalog, single currency, have a single development staff, single business team, and a relatively simple business model.  The real complex applications have to support multiple sites, multiple languages, multiple catalogs, multiple currencies, a couple different development teams, multiple business teams, and a highly complex business model (and processes to go along with it).  While it's still important to implement a proper design for simple applications, it's absolutely critical to do this for the complex applications.  Why?  It's all about time and money.  If you are unable to manage your complex applications in an efficient manner, the cost of managing it will increase dramatically as will the time to get things done (time to market).  On the positive side, your competition is most likely in the same situation, so you just need to be more efficient than they are. This article is intended to discuss a number of key areas to think about when designing complex applications on ATG.  Some of this can get fairly technical, so it may help to get some background first.  You can get enough of the required background information from this post.  After reading that, come back here and follow along. Application Design Of all the various types of ATG applications out there, the most complex tend to be the ones in the telecommunications industry - especially the ones which operate in multiple countries.  To get started, let's assume that we are talking about an application like that.  One that has these properties: Operates in multiple countries - must support multiple sites, catalogs, languages, and currencies The organization is fairly loosely-coupled - single brand, but different businesses across different countries There is some common functionality across all sites in all countries There is some common functionality across different sites within the same country Sites within a single country may have some unique functionality - relative to other sites in the same country Complex product catalog (mostly in terms of bundles, eligibility, and compatibility) At this point, I'll assume you have read through the required reading and have a decent understanding of how ATG modules work... Code / configuration - assemble into modules When it comes to defining your modules for a complex application, there are a number of goals: Divide functionality between the modules in a way that maps to your business Group common functionality 'further down in the stack of modules' Provide a good balance between shared resources and autonomy for countries / sites Now I'll describe a high level approach to how you could accomplish those goals...  Let's start from the bottom and work our way up.  At the very bottom, you have the modules that ship with ATG - the 'out of the box' stuff.  You want to make sure that you are leveraging all the modules that make sense in order to get the most value from ATG as possible - and less stuff you'll have to write yourself.  On top of the ATG modules, you should create what we'll refer to as the Corporate Foundation Module described as follows: Sits directly on top of ATG modules Used by all applications across all countries and sites - this is the foundation for everyone Contains everything that is common across all countries / all sites Once established and settled, will change less frequently than other 'higher' modules Encapsulates as many enterprise-wide integrations as possible Will provide means of code sharing therefore less development / testing - faster time to market Contains a 'reference' web application (described below) The next layer up could be multiple modules for each country (you could replace this with region if that makes more sense).  We'll define those modules as follows: Sits on top of the corporate foundation module Contains what is unique to all sites in a given country Responsible for managing any resource bundles for this country (to handle multiple languages) Overrides / replaces corporate integration points with any country-specific ones Finally, we will define what should be a fairly 'thin' (in terms of functionality) set of modules for each site as follows: Sits on top of the country it resides in module Contains what is unique for a given site within a given country Will mostly contain configuration, but could also define some unique functionality as well Contains one or more web applications The graphic below should help to indicate how these modules fit together: Web applications As described in the previous section, there are many opportunities for sharing (minimizing costs) as it relates to the code and configuration aspects of ATG modules.  Web applications are also contained within ATG modules, however, sharing web applications can be a bit more difficult because this is what the end customer actually sees, and since each site may have some degree of unique look & feel, sharing becomes more challenging.  One approach that can help is to define a 'reference' web application at the corporate foundation layer to act as a solid starting point for each site.  Here's a description of the 'reference' web application: Contains minimal / sample reference styling as this will mostly be addressed at the site level web app Focus on functionality - ensure that core functionality is revealed via this web application Each individual site can use this as a starting point There may be multiple types of web apps (i.e. B2C, B2B, etc) There are some techniques to share web application assets - i.e. multiple web applications, defined in the web.xml, and it's worth investigating, but is out of scope here. Reference infrastructure In this complex environment, it is assumed that there is not a single infrastructure for all countries and all sites.  It's more likely that different countries (or regions) could have their own solution for infrastructure.  In this case, it will be advantageous to define a reference infrastructure which contains all the hardware and software that make up the core environment.  Specifications and diagrams should be created to outline what this reference infrastructure looks like, as well as it's baseline cost and the incremental cost to scale up with volume.  Having some consistency in terms of infrastructure will save time and money as new countries / sites come online.  Here are some properties of the reference infrastructure: Standardized approach to setup of hardware Type and number of servers Defines application server, operating system, database, etc... - including vendor and specific versions Consistent naming conventions Provides a consistent base of terminology and understanding across environments Defines which ATG services run on which servers Production Staging BCC / Preview Each site can change as required to meet scale requirements Governance / organization It should be no surprise that the complex application we're talking about is backed by an equally complex organization.  One of the more challenging aspects of efficiently managing a series of complex applications is to ensure the proper level of governance and organization.  Here are some ideas and goals to work towards: Establish a committee to make enterprise-wide decisions that affect all sites Representation should be evenly distributed Should have a clear communication procedure Focus on high level business goals Evaluation of feature / function gaps and how that relates to ATG release schedule / roadmap Determine when to upgrade & ensure value will be realized Determine how to manage various levels of modules Who is responsible for maintaining corporate / country / site layers Determine a procedure for controlling what goes in the corporate foundation module Standardize on source code control, database, hardware, OS versions, J2EE app servers, development procedures, etc only use tested / proven versions - this is something that should be centralized so that every country / site does not have to worry about compatibility between versions Create a innovation team Quickly develop new features, perform proof of concepts All teams can benefit from their findings Summary At this point, it should be clear why the topics above (design, governance, organization, etc) are critical to being able to efficiently manage a complex application.  To summarize, it's all about competitive advantage...  You will need to reduce costs and improve time to market with the goal of providing a better experience for your end customers.  You can reduce cost by reducing development time, time allocated to testing (don't have to test the corporate foundation module over and over again - do it once), and optimizing operations.  With an efficient design, you can improve your time to market and your business will be more flexible  and agile.  Over time, you'll find that you're becoming more focused on offering functionality that is new to the market (creativity) and this will be rewarded - you're now a leader. In addition to the above, you'll realize soft benefits as well.  Your staff will be operating in a culture based on sharing.  You'll want to reward efforts to improve and enhance the foundation as this will benefit everyone.  This culture will inspire innovation, which can only lend itself to your competitive advantage.

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  • Master Data

    - by david.butler(at)oracle.com
    Let's take a deeper look at what we mean when we talk about 'Master' data. In its most general sense, master data is data that exists in more than one operational application. These are the applications that automate business processes. These applications require significant amounts of data to function correctly.  This includes data about the objects that are involved in transactions, as well as the transaction data itself.  For example, when a customer buys a product, the transaction is managed by a sales application.  The objects of the transaction are the Customer and the Product.  The transactional data is the time, place, price, discount, payment methods, etc. used at the point of sale. Many thousands of transactional data attributes are needed within the application. These important data elements are local to the applications and have no bearing on other applications. Harmonization and synchronization across applications is not necessary. The Customer and Product objects of the transaction also have a large number of attributes. Customer for example, includes hierarchies, hierarchical and matrixed relationships, contacts, classifications, preferences, accounts, identifiers, profiles, and addresses galore for 'ship to', 'mail to'; 'service at'; etc. Dozens of attributes exist for individuals, hundreds for organizations, and thousands for products. This data has meaning beyond any particular application. It exists in many applications and drives the vital cross application enterprise business processes. These are the processes that define and differentiate the organization. At every decision point, information about the objects of the process determines the direction of the process flow. This is the nature of the data that exists in more than one application, and this is why we call it 'master data'. Let me elaborate. Parties Oracle has developed a party schema to model all participants in your daily business operations. It models people, organizations, groups, customers, contacts, employees, and suppliers. It models their accounts, locations, classifications, and preferences.  And most importantly, it models the vast array of hierarchical and matrixed relationships that exist between all the participants in your real world operations.  The model logically separates people and organizations from their relationships and accounts.  This separation creates flexibility unmatched in the industry and accounts for the fact that the Oracle schema for Customers, Suppliers, and Accounts is a true superset of the wide variety of commercial and homegrown customer models in existence. Sites Sites are places where business is conducted. They can be addresses, clusters such as retail malls, locations within a cluster, floors within a building, places where meters are located, rooms on floors, etc.  Fully understanding all attributes of a site is key to many business processes. Attributes such as 'noise abatement policy' at a point of delivery, or the size of an oven in a business kitchen drive day-to-day activities such as delivery schedules or food promotions. Typically this kind of data is siloed in departments and scattered across applications and spreadsheets.  This leads to conflicting information and poor operational efficiencies. Oracle's Global Single Schema can hold all site attributes in one place and enables a single version of authoritative site information across the enterprise. Products and Services The Oracle Global Single Schema also includes a number of entities that define the products and services a company creates and offers for sale. Key entities include Items organized into Catalogs and Price Lists. The Catalog structures provide for the ability to capture different views of a product such as engineering, manufacturing, and service which are based on a unified product model. As a result, designers, manufacturing engineers, purchasers and partners can work simultaneously on a common product definition. The Catalog schema allows for unlimited attributes, combines them into meaningful groups, and maps them to catalog categories to track these different types of information. The model also maps an unlimited number of functional structures for each item. For example, multiple Bills of Material (BOMs) can be constructed representing requirements BOM, features BOM, and packaging BOM for an item. The Catalog model also supports hierarchical information about each item and all standard Global Data Synchronization attributes. Business Processes Utilizing Linked Data Entities Each business entity codified into a centralized master data environment significantly improves the efficiency of the automated business processes that use the consolidated data.  When all the key business entities used by an organization's process are so consolidated, the advantages are multiplied.  The primary reason for business process breakdowns (i.e. data errors across application boundaries) is eliminated. All processes are positively impacted and business process automation is itself automated.  I like to use the "Call to Resolution" business process as an example to help illustrate this important point. It involves call center applications, service applications, RMA applications, transportation applications, inventory applications, etc. Customer, Site, Product and Supplier master data must all be correct and consistent across these applications.  What's more, the data relationships between customer and product, and product and suppliers must be right. This is the minimum quality needed to insure the business process flows without error. But that is not the end of the story. Critical master data attributes such as customer loyalty, profitability, credit worthiness, and propensity to buy can optimize the call center point of contact component of the process. Critical product information such as alternative parts or equivalent products can optimize the resolution selected by the process. A comprehensive understanding of the 'service at' location can help insure multiple trips are avoided in the process. Full supplier information on reliability, delivery delays, and potential alternates can prevent supplier exceptions and play a significant role in optimizing the process.  In other words, these master data attributes enable the optimization of the "Call to Resolution" enterprise business process. Master data supports and guides business process flows. Thus the phrase 'Master Data' is indeed appropriate. MDM is the software that houses, manages, and governs the master data that resides in all applications and controls the enterprise business processes. A complete master data solution takes a data model that holds fully attributed master data entities and their inter-relationships. Oracle has this model. Oracle, with its deep understanding of application data is the logical choice for managing all your master data within the enterprise whether or not your organization actually runs any Oracle Applications.

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  • Can't get Xdebug to work on Windows 7

    - by Derek
    I installed the latest XAMPP package which includes PHP 5.3.0. I am trying to enable Xdebug, but it just won't work. Here's what I changed in the php.ini shipped with XAMPP: ; uncommented zend_extension = "X:\xampp\php\ext\php_xdebug.dll" ; added the following lines: xdebug.remote_enable=true xdebug.remote_host=localhost xdebug.remote_port=9000 xdebug.remote_handler=dbgp Apache starts fine, but when I open http://localhost/ in my browser, I get the following error If I click the Close the program button, the error message will reappear in a second as if it was in an infinite loop. I'd greatly appreciate any help in getting this to work. I am running a fresh install of Windows 7 Ultimate 64-bit. EDIT: From the result of phpinfo(): Zend Extension Build API220090626,TS,VC6 PHP Extension Build API20090626,TS,VC6 Debug Build no Thread Safety enabled

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  • Are JSF 2.x ViewScoped Beans Thread Safe?

    - by Mark
    I've been googling for a couple hours on this issue to no eval. WELD docs and the CDI spec are pretty clear regarding thread safety of the scopes provided. For example: Application Scope - not safe Session Scope - not safe Request Scope - safe, always bound to a single thread Conversation Scope - safe (due to the WELD proxy serializing access from multiple request threads) I can't find anything on the View Scope defined by JSF 2.x. It is in roughly the same bucket as the Conversation Scope in that it is very possible for multiple requests to hit the scope concurrently despite it being bound to a single view / user. What I don't know is if the JSF implementation serializes access to the bean from multiple requests. Anyone have knowledge of the spec or of the Morraja/MyFaces implementations that could clear this up?

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  • The Future of Project Management is Social

    - by Natalia Rachelson
    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:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} A guest post by Kazim Isfahani, Director, Product Marketing, Oracle Rapid Ascent. Breakneck Speed. Lightning Fast. Perhaps even overwhelming. No matter which set of adjectives we use to describe it, social media’s rise into the enterprise mainstream has been unprecedented. Indeed, the big 4 social media powerhouses (Facebook, Google+, LinkedIn, and Twitter), have nearly 2 Billion users between them. You may be asking (as you should really) “That’s all well and good for the consumer, but for me at my company, what’s your point? Beyond the fact that I can check and post updates, that is.” Good question, kind sir. Impact of Social and Collaboration on Project Management I’ll dovetail this discussion to the project management realm, since that’s what I’m writing about. Speed is a big challenge for project-driven organizations. Anything that can help speed up project delivery - be it a new product introduction effort or a geographical expansion project - fast is a good thing. So where does this whole social thing fit particularly since there are already a host of tools to help with traditional project execution? The fact is companies have seen improvements in their productivity by deploying departmental collaboration and other social-oriented solutions. McKinsey’s survey on social tools shows we have reached critical scale: 72% of respondents report that their companies use at least one and over 40% say they are using social networks and blogs. We don’t hear as much about the impact of social media technologies at the project and project manager level, but that does not mean there is none. Consider the new hire. The type of individual entering the workforce and executing on projects is a generation of worker expecting visually appealing, easy to use and easy to understand technology meshing hand-in-hand with business processes. Consider the project manager. The social era has enhanced the role that the project manager must play. Today’s project manager must be a supreme communicator, an influencer, a sympathizer, a negotiator, and still manage to keep all stakeholders in the loop on project progress. Social tools play a significant role in this effort. Now consider the impact to the project team. The way that a project team functions has changed, with newer, social oriented technologies making the process of information dissemination and team communications much more fluid. It’s clear that a shift is occurring where “social” is intersecting with project management. The Rise of Social Project Management We refer to the melding of project management and social networking as Social Project Management. Social Project Management is based upon the philosophy that the project team is one part of an integrated whole, and that valuable and unique abilities exist within the larger organization. For this reason, Social Project Management systems should be integrated into the collaborative platform(s) of an organization, allowing communication to proceed outside the project boundaries. What makes social project management "social" is an implicit awareness where distributed teams build connected links in ways that were previously restricted to teams that were co-located. Just as critical, Social Project Management embraces the vision of seamless online collaboration within a project team, but also provides for, (and enhances) the use of rigorous project management techniques. Social Project Management acknowledges that projects (particularly large projects) are a social activity - people doing work with people, for other people, with commitments to yet other people. The more people (larger projects), the more interpersonal the interactions, and the more social affects the project. The Epitome of Social - Fusion Project Portfolio Management If I take this one level further to discuss Fusion Project Portfolio Management, the notion of Social Project Management is on full display. With Fusion Project Portfolio Management, project team members have a single place for interaction on projects and access to any other resources working within the Fusion ERP applications. This allows team members the opportunity to be informed with greater participation and provide better information. The application’s the visual appeal, and highly graphical nature makes it easy to navigate information. The project activity stream adds to the intuitive user experience. The goal of productivity is pervasive throughout Fusion Project Portfolio Management. Field research conducted with Oracle customers and partners showed that users needed a way to stay in the context of their core transactions and yet easily access social networking tools. This is manifested in the application so when a user executes a business process, they not only have the transactional application at their fingertips, but also have things like e-mail, SMS, text, instant messaging, chat – all providing a number of different ways to interact with people and/or groups of people, both internal and external to the project and enterprise. But in the end, connecting people is relatively easy. The larger issue is finding a way to serve up relevant, system-generated, actionable information, in real time, which will allow for more streamlined execution on key business processes. Fusion Project Portfolio Management’s design concept enables users to create project communities, establish discussion threads, manage event calendars as well as deliver project based work spaces to organize communications within the context of a project – all within a secure business environment. We’d love to hear from you and get your thoughts and ideas about how Social Project Management is impacting your organization. To learn more about Oracle Fusion Project Portfolio Management, please visit this link

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  • NUMA-aware placement of communication variables

    - by Dave
    For classic NUMA-aware programming I'm typically most concerned about simple cold, capacity and compulsory misses and whether we can satisfy the miss by locally connected memory or whether we have to pull the line from its home node over the coherent interconnect -- we'd like to minimize channel contention and conserve interconnect bandwidth. That is, for this style of programming we're quite aware of where memory is homed relative to the threads that will be accessing it. Ideally, a page is collocated on the node with the thread that's expected to most frequently access the page, as simple misses on the page can be satisfied without resorting to transferring the line over the interconnect. The default "first touch" NUMA page placement policy tends to work reasonable well in this regard. When a virtual page is first accessed, the operating system will attempt to provision and map that virtual page to a physical page allocated from the node where the accessing thread is running. It's worth noting that the node-level memory interleaving granularity is usually a multiple of the page size, so we can say that a given page P resides on some node N. That is, the memory underlying a page resides on just one node. But when thinking about accesses to heavily-written communication variables we normally consider what caches the lines underlying such variables might be resident in, and in what states. We want to minimize coherence misses and cache probe activity and interconnect traffic in general. I don't usually give much thought to the location of the home NUMA node underlying such highly shared variables. On a SPARC T5440, for instance, which consists of 4 T2+ processors connected by a central coherence hub, the home node and placement of heavily accessed communication variables has very little impact on performance. The variables are frequently accessed so likely in M-state in some cache, and the location of the home node is of little consequence because a requester can use cache-to-cache transfers to get the line. Or at least that's what I thought. Recently, though, I was exploring a simple shared memory point-to-point communication model where a client writes a request into a request mailbox and then busy-waits on a response variable. It's a simple example of delegation based on message passing. The server polls the request mailbox, and having fetched a new request value, performs some operation and then writes a reply value into the response variable. As noted above, on a T5440 performance is insensitive to the placement of the communication variables -- the request and response mailbox words. But on a Sun/Oracle X4800 I noticed that was not the case and that NUMA placement of the communication variables was actually quite important. For background an X4800 system consists of 8 Intel X7560 Xeons . Each package (socket) has 8 cores with 2 contexts per core, so the system is 8x8x2. Each package is also a NUMA node and has locally attached memory. Every package has 3 point-to-point QPI links for cache coherence, and the system is configured with a twisted ladder "mobius" topology. The cache coherence fabric is glueless -- there's not central arbiter or coherence hub. The maximum distance between any two nodes is just 2 hops over the QPI links. For any given node, 3 other nodes are 1 hop distant and the remaining 4 nodes are 2 hops distant. Using a single request (client) thread and a single response (server) thread, a benchmark harness explored all permutations of NUMA placement for the two threads and the two communication variables, measuring the average round-trip-time and throughput rate between the client and server. In this benchmark the server simply acts as a simple transponder, writing the request value plus 1 back into the reply field, so there's no particular computation phase and we're only measuring communication overheads. In addition to varying the placement of communication variables over pairs of nodes, we also explored variations where both variables were placed on one page (and thus on one node) -- either on the same cache line or different cache lines -- while varying the node where the variables reside along with the placement of the threads. The key observation was that if the client and server threads were on different nodes, then the best placement of variables was to have the request variable (written by the client and read by the server) reside on the same node as the client thread, and to place the response variable (written by the server and read by the client) on the same node as the server. That is, if you have a variable that's to be written by one thread and read by another, it should be homed with the writer thread. For our simple client-server model that means using split request and response communication variables with unidirectional message flow on a given page. This can yield up to twice the throughput of less favorable placement strategies. Our X4800 uses the QPI 1.0 protocol with source-based snooping. Briefly, when node A needs to probe a cache line it fires off snoop requests to all the nodes in the system. Those recipients then forward their response not to the original requester, but to the home node H of the cache line. H waits for and collects the responses, adjudicates and resolves conflicts and ensures memory-model ordering, and then sends a definitive reply back to the original requester A. If some node B needed to transfer the line to A, it will do so by cache-to-cache transfer and let H know about the disposition of the cache line. A needs to wait for the authoritative response from H. So if a thread on node A wants to write a value to be read by a thread on node B, the latency is dependent on the distances between A, B, and H. We observe the best performance when the written-to variable is co-homed with the writer A. That is, we want H and A to be the same node, as the writer doesn't need the home to respond over the QPI link, as the writer and the home reside on the very same node. With architecturally informed placement of communication variables we eliminate at least one QPI hop from the critical path. Newer Intel processors use the QPI 1.1 coherence protocol with home-based snooping. As noted above, under source-snooping a requester broadcasts snoop requests to all nodes. Those nodes send their response to the home node of the location, which provides memory ordering, reconciles conflicts, etc., and then posts a definitive reply to the requester. In home-based snooping the snoop probe goes directly to the home node and are not broadcast. The home node can consult snoop filters -- if present -- and send out requests to retrieve the line if necessary. The 3rd party owner of the line, if any, can respond either to the home or the original requester (or even to both) according to the protocol policies. There are myriad variations that have been implemented, and unfortunately vendor terminology doesn't always agree between vendors or with the academic taxonomy papers. The key is that home-snooping enables the use of a snoop filter to reduce interconnect traffic. And while home-snooping might have a longer critical path (latency) than source-based snooping, it also may require fewer messages and less overall bandwidth. It'll be interesting to reprise these experiments on a platform with home-based snooping. While collecting data I also noticed that there are placement concerns even in the seemingly trivial case when both threads and both variables reside on a single node. Internally, the cores on each X7560 package are connected by an internal ring. (Actually there are multiple contra-rotating rings). And the last-level on-chip cache (LLC) is partitioned in banks or slices, which with each slice being associated with a core on the ring topology. A hardware hash function associates each physical address with a specific home bank. Thus we face distance and topology concerns even for intra-package communications, although the latencies are not nearly the magnitude we see inter-package. I've not seen such communication distance artifacts on the T2+, where the cache banks are connected to the cores via a high-speed crossbar instead of a ring -- communication latencies seem more regular.

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  • Will pool the connection help threading in sqlite (and how)?

    - by mamcx
    I currently use a singleton to acces my database (see related question) but now when try to add some background processing everything fall apart. I read the sqlite docs and found that sqlite could work thread-safe, but each thread must have their own db connection. I try using egodatabase that promise a sqlite wrapper with thread safety but is very buggy, so I return to my old FMDB library I start to see how use it in multi-thread way. Because I have all code with the idea of singleton, change everything will be expensive (and a lot of open/close connections could become slow), so I wonder if, as the sqlite docs hint, build a pooling for each connection will help. If is the case, how make it? How know wich connection get from the pool (because 2 threads can't share the connection)? I wonder if somebody already use sqlite in multu-threading with NSOperation or similar stuff, my searching only return "yeah, its possible" but let the details to my imagination...

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  • Conversion of pointer-to-pointer between derived and base classes?

    - by Mike Mueller
    Regarding the following C++ program: class Base { }; class Child : public Base { }; int main() { // Normal: using child as base is allowed Child *c = new Child(); Base *b = c; // Double pointers: apparently can't use Child** as Base** Child **cc = &c; Base **bb = cc; return 0; } GCC produces the following error on the last assignment statement: error: invalid conversion from ‘Child**’ to ‘Base**’ My question is in two parts: Why is there no implicit conversion from Child** to Base**? I can make this example work with a C-style cast or a reinterpret_cast. Using these casts means throwing away all type safety. Is there anything I can add to the class definitions to make these pointers cast implicitly, or at least phrase the conversion in a way that allows me to use static_cast instead?

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  • C++ 'mutable' keyword

    - by Rob
    A while ago I came across some code that marked a member variable of a class with the 'mutable' keyword. As far as I can see it simply allows you to modify a variable in a 'const' method: class Foo { private: mutable bool done_; public: void doSomething() const { ...; done_ = true; } }; Is this the only use of this keyword or is there more to it than meets the eye? I have since used this technique in a class, marking a boost::mutex as mutable allowing const functions to lock it for thread-safety reasons, but, to be honest, it feels like a bit of a hack.

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  • Return a dynamic string from std::exception's `what`

    - by Shtééf
    I'm convinced at this point that I should be creating subclasses of std::exception for all my exception throwing needs. Now I'm looking at how to override the what method. The situation that I'm facing, it would be really handy if the string what returns be dynamic. Some pieces of code parse an XML file for example, and adding a position or line number to the error message is useful to me. What I'd like to know: what returns a const char *, which implies any catcher is likely not going to free the string. So I need some other place to store the result, but where would that be? (I need thread-safety.) what also includes throw() in its signature. While I can prevent my what from throwing anything, it seems to me that this method really isn't intended for anything too dynamic. If what is not the right place, then where should I be doing this instead?

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  • How can I use my own connection class with a strongly typed dataset?

    - by Maslow
    I have designed a class with sqlClient.SqlCommand wrappers to implement such functionality as automatic retries on timeout, Async (thread safety), error logging, and some sql server functions like WhoAmI. I've used some strongly typed datasets mainly for display purposes only, but I'd like to have the same database functionality that I use with my class. Is there an interface I can implement or a way to hook my command/connection class into the dataset at design or runtime? Or would I need to somehow write a wrapper for the dataset to implement these types of functions? if this is the only option could it be made generic to wrap anything that inherits from dataset?

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  • Making swap faster, easier to use and exception-safe

    - by FredOverflow
    I could not sleep last night and started thinking about std::swap. Here is the familiar C++98 version: template <typename T> void swap(T& a, T& b) { T c(a); a = b; b = c; } If a user-defined class Foo uses external ressources, this is inefficient. The common idiom is to provide a method void Foo::swap(Foo& other) and a specialization of std::swap<Foo>. Note that this does not work with class templates since you cannot partially specialize a function template, and overloading names in the std namespace is illegal. The solution is to write a template function in one's own namespace and rely on argument dependent lookup to find it. This depends critically on the client to follow the "using std::swap idiom" instead of calling std::swap directly. Very brittle. In C++0x, if Foo has a user-defined move constructor and a move assignment operator, providing a custom swap method and a std::swap<Foo> specialization has little to no performance benefit, because the C++0x version of std::swap uses efficient moves instead of copies: #include <utility> template <typename T> void swap(T& a, T& b) { T c(std::move(a)); a = std::move(b); b = std::move(c); } Not having to fiddle with swap anymore already takes a lot of burden away from the programmer. Current compilers do not generate move constructors and move assignment operators automatically yet, but as far as I know, this will change. The only problem left then is exception-safety, because in general, move operations are allowed to throw, and this opens up a whole can of worms. The question "What exactly is the state of a moved-from object?" complicates things further. Then I was thinking, what exactly are the semantics of std::swap in C++0x if everything goes fine? What is the state of the objects before and after the swap? Typically, swapping via move operations does not touch external resources, only the "flat" object representations themselves. So why not simply write a swap template that does exactly that: swap the object representations? #include <cstring> template <typename T> void swap(T& a, T& b) { unsigned char c[sizeof(T)]; memcpy( c, &a, sizeof(T)); memcpy(&a, &b, sizeof(T)); memcpy(&b, c, sizeof(T)); } This is as efficient as it gets: it simply blasts through raw memory. It does not require any intervention from the user: no special swap methods or move operations have to be defined. This means that it even works in C++98 (which does not have rvalue references, mind you). But even more importantly, we can now forget about the exception-safety issues, because memcpy never throws. I can see two potential problems with this approach: First, not all objects are meant to be swapped. If a class designer hides the copy constructor or the copy assignment operator, trying to swap objects of the class should fail at compile-time. We can simply introduce some dead code that checks whether copying and assignment are legal on the type: template <typename T> void swap(T& a, T& b) { if (false) // dead code, never executed { T c(a); // copy-constructible? a = b; // assignable? } unsigned char c[sizeof(T)]; std::memcpy( c, &a, sizeof(T)); std::memcpy(&a, &b, sizeof(T)); std::memcpy(&b, c, sizeof(T)); } Any decent compiler can trivially get rid of the dead code. (There are probably better ways to check the "swap conformance", but that is not the point. What matters is that it's possible). Second, some types might perform "unusual" actions in the copy constructor and copy assignment operator. For example, they might notify observers of their change. I deem this a minor issue, because such kinds of objects probably should not have provided copy operations in the first place. Please let me know what you think of this approach to swapping. Would it work in practice? Would you use it? Can you identify library types where this would break? Do you see additional problems? Discuss!

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  • serialize/deserialize a LinkedHashMap (android) java

    - by user348058
    So i want to pass a LinkedHashMap to an intent. //SEND THE MAP Intent singlechannel = new Intent(getBaseContext(),singlechannel.class); singlechannel.putExtra("db",shows1);//perase to startActivity(singlechannel); //GET THE MAP LinkedHashMap<String,String> db = new LinkedHashMap<String,String>(); db=(LinkedHashMap<String,String>) getIntent().getSerializableExtra("db"); This one Worked Like a charm with HashMap. But with LinkedHashMap i got a problem I got a warning "Type safety: Unchecked cast from Serializable to LinkedHashMap" But i had this warning with HashMap too? Any ideas.Any help is much appreciated Also I just saw this. https://issues.apache.org/jira/browse/HARMONY-6498

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  • Webapp: safetly update a shared List/Map in the AppContext

    - by al nik
    I've Lists and Maps in my WebAppContext. Most of the time these are only read by multiple Threads but sometimes there's the need to update or add some data. I'm wondering what's the best way to do this without incurring in a ConcurrentModificationException. I think that using CopyOnWriteArrayList I can achieve what I want in terms of - I do not have to sync on every read operation- I can safety update the list while other threads are reading it. Is this the best solution? What about Maps?

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  • An algorithm Problem

    - by Vignesh
    For coverage, I've a set of run time variables of from my program execution. It happens that I get it from a series of executions(Automated testing). ie. its a vector<vector<var,value>> I've a limited set of variables with expected values and generate combination s, that is I have vector<vector<var,value>(smaller than the execution vector)>. Now I need to compare and tell which of the combination I generated were exactly executed in one of the tests. My algo is O(n^4). Is there any way to bring it down. Something like set intersection. I'm using java, and vectors because of thread safety.

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  • Best data-structure to use for two ended sorted list

    - by fmark
    I need a collection data-structure that can do the following: Be sorted Allow me to quickly pop values off the front and back of the list Remain sorted after I insert a new value Allow a user-specified comparison function, as I will be storing tuples and want to sort on a particular value Thread-safety is not required Optionally allow efficient haskey() lookups (I'm happy to maintain a separate hash-table for this though) My thoughts at this stage are that I need a priority queue and a hash table, although I don't know if I can quickly pop values off both ends of a priority queue. I'm interested in performance for a moderate number of items (I would estimate less than 200,000). Another possibility is simply maintaining an OrderedDictionary and doing an insertion sort it every-time I add more data to it. Furthermore, are there any particular implementations in Python. I would really like to avoid writing this code myself.

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  • Are concurrency issues possible when using the WCF Service Behavoir attribute set to ConcurrencyMode

    - by Brandon Linton
    We have a WCF service that makes a good deal of transactional NHibernate calls. Occasionally we were seeing SQL timeouts, even though the calls were updating different rows and the tables were set to row level locking. After digging into the logs, it looks like different threads were entering the same point in the code (our transaction using block), and an update was hanging on commit. It didn't make sense, though, because we believed that the following service class attribute was forcing a unique execution thread per service call: [ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Multiple, InstanceContextMode = InstanceContextMode.PerCall)] We recently changed the concurrency mode to ConcurrencyMode.Single and haven't yet run into any issues, but the bug was very difficult to reproduce (if anyone has any thoughts on flushing a bug like that out, let me know!). Anyway, that all brings me to my question: shouldn't an InstanceContextMode of PerCall enforce thread-safety within the service, even if the ConcurrencyMode is set to multiple? How would it be possible for two calls to be serviced by the same service instance? Thanks!

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  • Notifications for Expiring DBSNMP Passwords

    - by Courtney Llamas
    Most user accounts these days have a password profile on them that automatically expires the password after a set number of days.   Depending on your company’s security requirements, this may be as little as 30 days or as long as 365 days, although typically it falls between 60-90 days. For a normal user, this can cause a small interruption in your day as you have to go get your password reset by an admin. When this happens to privileged accounts, such as the DBSNMP account that is responsible for monitoring database availability, it can cause bigger problems. In Oracle Enterprise Manager 12c you may notice the error message “ORA-28002: the password will expire within 5 days” when you connect to a target, or worse you may get “ORA-28001: the password has expired". If you wait too long, your monitoring will fail because the password is locked out. Wouldn’t it be nice if we could get an alert 10 days before our DBSNMP password expired? Thanks to Oracle Enterprise Manager 12c Metric Extensions (ME), you can! See the Oracle Enterprise Manager Cloud Control Administrator’s Guide for more information on Metric Extensions. To create a metric extension, select Enterprise / Monitoring / Metric Extensions, and then click on Create. On the General Properties screen select either Cluster Database or Database Instance, depending on which target you need to monitor.  If you have both RAC and Single instance you may need to create one for each. In this example we will create a Cluster Database metric.  Enter a Name for the ME and a Display Name. Then select SQL for the Adapter.  Adjust the Collection Schedule as desired, for this example we will collect this metric every 1 day. Notice for metric collected every day, we can determine the exact time we want to collect. On the Adapter page, enter the query that you wish to execute.  In this example we will use the query below that specifically checks for the DBSNMP user that is expiring within 10 days. Of course, you can adjust this query to alert for any user that can cause an outage such as an application account or service account such as RMAN. select username, account_status, trunc(expiry_date-sysdate) days_to_expirefrom dba_userswhere username = 'DBSNMP'and expiry_date is not null; The next step is to create the columns to store the data returned from the query.  Click Add and add a column for each of the fields in the same order that data is returned.  The table below will help you complete the column additions. Name Display Name Column Type Value Type Metric Category Unit Username User Name Key String Security AccountStatus Account Status Data String Security DaysToExpire Days Until Expiration Data Number Security Days When creating the DaysToExpire column, you can add a default threshold here for Warning and Critical (say < 10 and 5).  When all columns have been added, click Next. On the Credentials page, you can choose to use the default monitoring credentials or specify new credentials.  We will use the default credentials established for our target (dbsnmp). The next step is to test your Metric Extension.  Click on Add to select a target for testing, then click Select. Now click the button Run Test to execute the test against the selected target(s). We can see in the example below that the Metric Extension has executed and returned a value of 68 days to expire. Click Next to proceed. Review the metric extension in the final screen and click Finish. The metric will be created in Editable status.  Select the metric, click Actions and select Deployable Draft. You can do this once more to move to Published. Finally, we want to apply this metric to a target. When managing many targets, it’s best to add your metric to a template, for details on adding a Metric Extension to a template see the Administrator’s Guide. For this example, we will deploy this to a target directly. Select Actions / Deploy to Targets. Click Add and select the target you wish to deploy to and click Submit.  Once deployment is complete, we can go to the target and view the Metric & Collection Settings to see the new metric and its thresholds.   After some time, you will find the metric has collected and the days to expiration for DBSNMP user can be seen in the All Metrics view.   For metrics collected once per day, you may have to wait up to 24 hours to see the metric and current severity. In the example below, the current severity is Clear (green check) as it is not scheduled to expire within 10 days. To test the notification, we can edit the thresholds for the new metric so they trigger an alert.  Our password expires in 139 days, so we’ll change our Warning to 140 and leave Critical at 5, in our example we also changed the collection time to every 5 minutes.  At the next collection, you’ll find that the current severity changes to a Warning and any related Incident Rules would be triggered to create an Incident or Notification as desired. Now that you get a notification that your DBSNMP passwords is about to expire, you can use OEM Command Line Interface (EM CLI) verb update_db_password to change it at both the database target and the OEM target in one step.  The caveat is you must know the existing password to use the update_db_password command.  To learn more about EM CLI, see the Oracle Enterprise Manager Command Line Interface Guide.  Below is an example of changing the password with the update_db_password verb.  $ ./emcli update_db_password -target_name=emrep -target_type=oracle_database -user_name=dbsnmp -change_at_target=yes -change_all_references=yes Enter value for old_password :Enter value for new_password :Enter value for retype_new_password :Successfully submitted a job to change the password in Enterprise Manager and on the target database: "emrep"Execute "emcli get_jobs -job_id=FA66C1C4D663297FE0437656F20ACC84" to check the status of the job.Search for job name "CHANGE_PWD_JOB_FA66C1C4D662297FE0437656F20ACC84" on the Jobs home page to check job execution details. The subsequent job created will typically run quickly enough that a blackout is not needed, however if you submit a script with many targets to change, your job may run slower so adding a blackout to the script is recommended. $ ./emcli get_jobs -job_id=FA66C1C4D663297FE0437656F20ACC84 Name Type Job ID Execution ID Scheduled Completed TZ Offset Status Status ID Owner Target Type Target Name CHANGE_PWD_JOB_FA66C1C4D662297FE0437656F20ACC84 ChangePassword FA66C1C4D663297FE0437656F20ACC84 FA66C1C4D665297FE0437656F20ACC84 2014-05-28 09:39:12 2014-05-28 09:39:18 GMT-07:00 Succeeded 5 SYSMAN oracle_database emrep After implementing the above Metric Extension and using the EM CLI update_db_password verb, you will be able to stay on top of your DBSNMP password changes without experiencing an unplanned monitoring outage.  

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  • Is autoload thread-safe in Ruby 1.9?

    - by SFEley
    It seems to me that the Ruby community has been freaking out a little about autoload since this famous thread, discouraging its use for thread safety reasons. Does anyone know if this is no longer an issue in Ruby 1.9.1 or 1.9.2? I've seen a bit of talk about wrapping requires in mutexes and such, but the 1.9 changelogs (or at least as much as I've been able to find) don't seem to address this particular question. I'd like to know if I can reasonably start autoloading in 1.9-only libraries without any reasonable grief. Thanks in advance for any insights.

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  • Using read() directly into a C++ std:vector

    - by Joe
    I'm wrapping up user space linux socket functionality in some C++ for an embedded system (yes, this is probably reinventing the wheel again). I want to offer a read and write implementation using a vector. Doing the write is pretty easy, I can just pass &myvec[0] and avoid unnecessary copying. I'd like to do the same and read directly into a vector, rather than reading into a char buffer then copying all that into a newly created vector. Now, I know how much data I want to read, and I can allocate appropriately (vec.reserve). I can also read into &myvec[0], though this is probably a VERY BAD IDEA. Obviously doing this doesn't allow myvec.size to return anything sensible. Is there any way of doing this that 1) Doesn't completely feel yucky from a safety/C++ perspective and 2) Doesn't involve two copies of the data block - once from kernel to user space and once from a C char * style buffer into a C++ vector. Any thoughts collective?

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  • Let your Signature Experience drive IT-decision making

    - by Tania Le Voi
    Today’s CIO job description:  ‘’Align IT infrastructure and solutions with business goals and objectives ; AND while doing so reduce costs; BUT ALSO, be innovative, ensure the architectures are adaptable and agile as we need to act today on the changes that we may request tomorrow.”   Sound like an unachievable request? The fact is, reality dictates that CIO’s are put under this type of pressure to deliver more with less. In a past career phase I spent a few years as an IT Relationship Manager for a large Insurance company. This is a role that we see all too infrequently in many of our customers, and it’s a shame.  The purpose of this role was to build a bridge, a relationship between IT and the business. Key to achieving that goal was to ensure the same language was being spoken and more importantly that objectives were commonly understood - hence service and projects were delivered to time, to budget and actually solved the business problems. In reality IT and the business are already married, but the relationship is most often defined as ‘supplier’ of IT rather than a ‘trusted partner’. To deliver business value they need to understand how to work together effectively to attain this next level of partnership. The Business cannot compete if they do not get a new product to market ahead of the competition, or for example act in a timely manner to address a new industry problem such as a legislative change. An even better example is when the Application or Service fails and the Business takes a hit by bad publicity, being trending topics on social media and losing direct revenue from online channels. For this reason alone Business and IT need the alignment of their priorities and deliverables now more than ever! Take a look at Forrester’s recent study that found ‘many IT respondents considering themselves to be trusted partners of the business but their efforts are impaired by the inadequacy of tools and organizations’.  IT Meet the Business; Business Meet IT So what is going on? We talk about aligning the business with IT but the reality is it’s difficult to do. Like any relationship each side has different goals and needs and language can be a barrier; business vs. technology jargon! What if we could translate the needs of both sides into actionable information, backed by data both sides understand, presented in a meaningful way?  Well now we can with the Business-Driven Application Management capabilities in Oracle Enterprise Manager 12cR2! Enterprise Manager’s Business-Driven Application Management capabilities provide the information that IT needs to understand the impact of its decisions on business criteria.  No longer does IT need to be focused solely on speeds and feeds, performance and throughput – now IT can understand IT’s impact on business KPIs like inventory turns, order-to-cash cycle, pipeline-to-forecast, and similar.  Similarly, now the line of business can understand which IT services are most critical for the KPIs they care about. There are a good deal of resources on Oracle Technology Network that describe the functionality of these products, so I won’t’ rehash them here.  What I want to talk about is what you do with these products. What’s next after we meet? Where do you start? Step 1:  Identify the Signature Experience. This is THE business process (or set of processes) that is core to the business, the one that drives the economic engine, the process that a customer recognises the company brand for, reputation, the customer experience, the process that a CEO would state as his number one priority. The crème de la crème of your business! Once you have nailed this it gets easy as Enterprise Manager 12c makes it easy. Step 2:  Map the Signature Experience to underlying IT.  Taking the signature experience, map out the touch points of the components that play a part in ensuring this business transaction is successful end to end, think of it like mapping out a critical path; the applications, middleware, databases and hardware. Use the wealth of Enterprise Manager features such as Systems, Services, Business Application Targets and Business Transaction Management (BTM) to assist you. Adding Real User Experience Insight (RUEI) into the mix will make the end to end customer satisfaction story transparent. Work with the business and define meaningful key performance indicators (KPI’s) and thresholds to enable you to report and action upon. Step 3:  Observe the data over time.  You now have meaningful insight into every step enabling your signature experience and you understand the implication of that experience on your underlying IT.  Watch if for a few months, see what happens and reconvene with your business stakeholders and set clear and measurable targets which can re-define service levels.  Step 4:  Change the information about which you and the business communicate.  It’s amazing what happens when you and the business speak the same language.  You’ll be able to make more informed business and IT decisions. From here IT can identify where/how budget is spent whether on the level of support, performance, capacity, HA, DR, certification etc. IT SLA’s no longer need be focused on metrics such as %availability but structured around business process requirements. The power of this way of thinking doesn’t end here. IT staff get to see and understand how their own role contributes to the business making them accountable for the business service. Take a step further and appraise your staff on the business competencies that are linked to the service availability. For the business, the language barrier is removed by producing targeted reports on the signature experience core to the business and therefore key to the CEO. Chargeback or show back becomes easier to justify as the ‘cost of day per outage’ can be more easily calculated; the business will be able to translate the cost to the business to the cost/value of the underlying IT that supports it. Used this way, Oracle Enterprise Manager 12c is a key enabler to a harmonious relationship between the end customer the business and IT to deliver ultimate service and satisfaction. Just engage with the business upfront, make the signature experience visible and let Enterprise Manager 12c do the rest. In the next blog entry we will cover some of the Enterprise Manager features mentioned to enable you to implement this new way of working.  

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