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• Need personal advice on how to get out of a company..

  - by SOfan

  Hi, I am an SO user since past 6 months and this is the first time I am turning to SO for personal help. I have asked technical questions before with my real ID. I am stuck inside a service based IT company for the past one year and haven't been able to decide if to leave it, when to leave it and how to leave it. I had taken 2 weeks LWP on medical reason roughly at end of 1 year and then soon after reporting, I applied for 2 months more LWP (on medical/personal ground) with the intention of working on my health,take up a hobby class to ward off depression,pessimism, to have some fun in life, and to look for a job which I really would be excited about - that interests me and which matches with my strength. My leave starts from this Monday. So in any case, I had hard set in mind that I will leave the company after I join them back hopefully with some job offer already in hand (after figuring out what I want do). Neither I can stand the past project,past colleagues,company, HR, pathetically low salary. But if I really listen to my heart, I don't want to have to go back to that office after my sabbatical and again have to see those people. I will have to resign it after my sabbatical ends. Then HR people perhaps wont like it, may even accuse me on face or behind back that primary purpose of my leave must have been to hunt for a better job and I lied about medical and person reasons. Also, if they get nasty and force me to serve 2 months notice period. There is no way I see myself after sabbatical resuming in old project or starting new work. It will be a pain. Since they have already approved 2 months leave and stuff, ideally if they want, they should be just able to relieve me right on the next day after I join back. But, I don't know if they want to get nasty, will they mention about my 2 months sabbatical leave in my experience letter or more scary, the term medical/personal reason. I have hard earned my experience here, have worked against my will, mostly it has been painful and slogged like anything, because I realize the importance of work experience in IT industry. I don't have greed to have those 2 months included extra in my experience letter, but I don't want to mess up with my experience letter in a way which makes my next employer ask question, get suspicious, or be wary if I have any medical reason going on. Being an emotional,moody person or somebody who can't be in an environment, once my mind and heart starts hating it. I think it perhaps is best, if I resign on Monday itself telling them (in polite manner) something that look I took sabbatical for some reason but I don't want to resume working in the company after my sabbatical ends. So please accept my resignation. Now tell me what you want to do about my leave request, my notice period and when you are willing to relieve me. What should I write and how? Some background: I am working in an IT company in India.I am overqualified in the company. It is grossly underpaying me. My education qualifications far exceed anyone's in the whole company being a CS undergrad as well as a CS grad. I joined this company after finishing the grad. I had self-doubts about my skills and interest as a programmer. I like doing research oriented work, though didn't have any particular success during grad. My life here has been very hectic. The project containing many many sub-projects has kept me on my toes and I have never really liked the work. I have been playing against my strength. Also the company strict internet usage policy (you can't read gmails, can't browse any non-work related sites not even news). When working for a client, from the machine we can't even check company related emails.For this one has to go to kiosk like 5 machines in a small room etc. Most of the times those machines are not available, so it was not unusual to keep making rounds to these kiosk machines to check company emails, browse company related emails etc.So it was not so easy to keep in touch with company related basic affairs for a not particular careful person. Things like this which are new to me, make me feel restricted. I am an undecisive person with a sense of failure, self-doubt, not meeting up unrealistic expectation. Somewhere at back of mind, I envy my classmates who make a smooth transition from company to company without causing any gap in their resume. I on other hand have gaps in resume. I get tired after working in a place for sometime. problem with colleagues in general. I am not particular great with people, have few friends, not known for a fun nature, rather serious, scholar. I am not a typical conventional female. I think females are usually more disciplined. But I am not so. I reach office late (though after informing manager). I don't want to blame them entirely, because from my past, it is not unusual for me to get undecisive on things. Also I had doubts about my ability as researched and to succeed there. of building a relationship in a group, to have something to talk about, newspaper. I get cut-off from people. peer pressure. I make blunders in coding, lose patience. Consciously or unconsciously I feel contempt for people here, work here, environment here. I have doubts that either I go to a place which does innovation, does research oriented work, product biggies, have great motivated people, have competent people passionate about products they are building. But then I also doubt my ability to survive there. I have identified that an idea job for me would be 4 days a week, a high salary job. When among people in company/team, I can't think much. I need some time at home to read good authentic books written in good style on what work I am doing.So that I am comfortable with my understanding of work. I get into pressure easily under deadline and need 5th day to cool myself off. I took for 2 weeks leave, because each day was hell for me. May be the depression phase of bipolar is on and also partially it could be that being a work centered person, who derives happiness,self-esteem from work, haven't been enjoying work and have been working for the sole person of proving stability, and ability to stick, against all odds, and facing what challenges I see, bonding with people, identifying opportunities to learn in given task etc.have been averaging one day LWP in 1 week or 10 days. or may be because of my nature,ADD,not being able to switch context,out of touch with news, don't have a circle of friends with who I enjoy. less knowledge in general to talk about, just some technical stuff.anyway, so due to emotional reason, some practical reason etc, I wanted to be very sure before leaving. So my leave starts from Monday and I should feel happy about it. I have taken the leave to for a few purposes - to take care of my health by regular yoga/exercise (with project on, I just can't do anything regular), reassess myself to see what I want to try next which work I might like, look for next job, take up a hobby which I like say singing. I am not clear on my career,job aspiration. I have tried my hands on research. During this year appraisal yesterday, I even had some conflict with my last manager. In meeting with me one on one, he would say all nice things about me, but in feedback to new manager, he hasn't given any excellent feedback. It is all only good. I am angry at this old Manager. Also new manager also scolded me as I didn't agree to his appraisal and waited to hear myself from old Manager. He kind of scolded me for wasting his time. Am I being unethical somewhere? I am always very conscious of if I am cheating anywhere. What advice I am seeking? How to resign and what to write in resignation letter

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• Multiple setInterval in a HTML5 Canvas game

  - by kushsolitary

  I'm trying to achieve multiple animations in a game that I am creating using Canvas (it is a simple ping-pong game). This is my first game and I am new to canvas but have created a few experiments before so I have a good knowledge about how canvas work. First, take a look at the game here. The problem is, when the ball hits the paddle, I want a burst of n particles at the point of contact but that doesn't came right. Even if I set the particles number to 1, they just keep coming from the point of contact and then hides automatically after some time. Also, I want to have the burst on every collision but it occurs on first collision only. I am pasting the code here: //Initialize canvas var canvas = document.getElementById("canvas"), ctx = canvas.getContext("2d"), W = window.innerWidth, H = window.innerHeight, particles = [], ball = {}, paddles = [2], mouse = {}, points = 0, fps = 60, particlesCount = 50, flag = 0, particlePos = {}; canvas.addEventListener("mousemove", trackPosition, true); //Set it's height and width to full screen canvas.width = W; canvas.height = H; //Function to paint canvas function paintCanvas() { ctx.globalCompositeOperation = "source-over"; ctx.fillStyle = "black"; ctx.fillRect(0, 0, W, H); } //Create two paddles function createPaddle(pos) { //Height and width this.h = 10; this.w = 100; this.x = W/2 - this.w/2; this.y = (pos == "top") ? 0 : H - this.h; } //Push two paddles into the paddles array paddles.push(new createPaddle("bottom")); paddles.push(new createPaddle("top")); //Setting up the parameters of ball ball = { x: 2, y: 2, r: 5, c: "white", vx: 4, vy: 8, draw: function() { ctx.beginPath(); ctx.fillStyle = this.c; ctx.arc(this.x, this.y, this.r, 0, Math.PI*2, false); ctx.fill(); } }; //Function for creating particles function createParticles(x, y) { this.x = x || 0; this.y = y || 0; this.radius = 0.8; this.vx = -1.5 + Math.random()*3; this.vy = -1.5 + Math.random()*3; } //Draw everything on canvas function draw() { paintCanvas(); for(var i = 0; i < paddles.length; i++) { p = paddles[i]; ctx.fillStyle = "white"; ctx.fillRect(p.x, p.y, p.w, p.h); } ball.draw(); update(); } //Mouse Position track function trackPosition(e) { mouse.x = e.pageX; mouse.y = e.pageY; } //function to increase speed after every 5 points function increaseSpd() { if(points % 4 == 0) { ball.vx += (ball.vx < 0) ? -1 : 1; ball.vy += (ball.vy < 0) ? -2 : 2; } } //function to update positions function update() { //Move the paddles on mouse move if(mouse.x && mouse.y) { for(var i = 1; i < paddles.length; i++) { p = paddles[i]; p.x = mouse.x - p.w/2; } } //Move the ball ball.x += ball.vx; ball.y += ball.vy; //Collision with paddles p1 = paddles[1]; p2 = paddles[2]; if(ball.y >= p1.y - p1.h) { if(ball.x >= p1.x && ball.x <= (p1.x - 2) + (p1.w + 2)){ ball.vy = -ball.vy; points++; increaseSpd(); particlePos.x = ball.x, particlePos.y = ball.y; flag = 1; } } else if(ball.y <= p2.y + 2*p2.h) { if(ball.x >= p2.x && ball.x <= (p2.x - 2) + (p2.w + 2)){ ball.vy = -ball.vy; points++; increaseSpd(); particlePos.x = ball.x, particlePos.y = ball.y; flag = 1; } } //Collide with walls if(ball.x >= W || ball.x <= 0) ball.vx = -ball.vx; if(ball.y > H || ball.y < 0) { clearInterval(int); } if(flag == 1) { setInterval(emitParticles(particlePos.x, particlePos.y), 1000/fps); } } function emitParticles(x, y) { for(var k = 0; k < particlesCount; k++) { particles.push(new createParticles(x, y)); } counter = particles.length; for(var j = 0; j < particles.length; j++) { par = particles[j]; ctx.beginPath(); ctx.fillStyle = "white"; ctx.arc(par.x, par.y, par.radius, 0, Math.PI*2, false); ctx.fill(); par.x += par.vx; par.y += par.vy; par.radius -= 0.02; if(par.radius < 0) { counter--; if(counter < 0) particles = []; } } } var int = setInterval(draw, 1000/fps); Now, my function for emitting particles is on line 156, and I have called this function on line 151. The problem here can be because of I am not resetting the flag variable but I tried doing that and got more weird results. You can check that out here. By resetting the flag variable, the problem of infinite particles gets resolved but now they only animate and appear when the ball collides with the paddles. So, I am now out of any solution.

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• The True Cost of a Solution

  - by D'Arcy Lussier

  I had a Twitter chat recently with someone suggesting Oracle and SQL Server were losing out to OSS (Open Source Software) in the enterprise due to their issues with scaling or being too generic (one size fits all). I challenged that a bit, as my experience with enterprise sized clients has been different – adverse to OSS but receptive to an established vendor. The response I got was: Found it easier to influence change by showing how X can’t solve our problems or X is extremely costly to scale. Money talks. I think this is definitely the right approach for anyone pitching an alternate or alien technology as part of a solution: identify the issue, identify the solution, then present pros and cons including a cost/benefit analysis. What can happen though is we get tunnel vision and don’t present a full view of the costs associated with a solution. An “Acura”te Example (I’m so clever…) This is my dream vehicle, a Crystal Black Pearl coloured Acura MDX with the SH-AWD package! We’re a family of 4 (5 if my daughters ever get their wish of adding a dog), and I’ve always wanted a luxury type of vehicle, so this is a perfect replacement in a few years when our Rav 4 has hit the 8 – 10 year mark. MSRP – $62,890 But as we all know, that’s not *really* the cost of the vehicle. There’s taxes and fees added on, there’s the extended warranty if I choose to purchase it, there’s the finance rate that needs to be factored in… MSRP –   $62,890 Taxes –      $7,546 Warranty - $2,500 SubTotal – $72,936 Finance Charge – $ 1094.04 Grand Total – $74,030 Well! Glad we did that exercise – we discovered an extra $11k added on to the MSRP! Well now we have our true price…or do we? Lifetime of the Vehicle I’m expecting to have this vehicle for 7 – 10 years. While the hard cost of the vehicle is known and dealt with, the costs to run and maintain the vehicle are on top of this. I did some research, and here’s what I’ve found: Fuel and Mileage Gas prices are high as it is for regular fuel, but getting into an MDX will require that I *only* purchase premium fuel, which comes at a premium price. I need to expect my bill at the pump to be higher. Comparing the MDX to my 2007 Rav4 also shows I’ll be gassing up more often. The Rav4 has a city MPG of 21, while the MDX plummets to 16! The MDX does have a bigger fuel tank though, so all in all the number of times I hit the pumps might even out. Still, I estimate I’ll be spending approximately $8000 – $10000 more on gas over a 10 year period than my current Rav4. Service Options Limited Although I have options with my Toyota here in Winnipeg (we have 4 Toyota dealerships), I do go to my original dealer for any service work. Still, I like the fact that I have options. However, there’s only one Acura dealership in all of Winnipeg! So if, for whatever reason, I’m not satisfied with the level of service I’m stuck. Non Warranty Service Work Also let’s not forget that there’s a bulk of work required every year that is *not* covered under warranty – oil changes, tire rotations, brake pads, etc. I expect I’ll need to get new tires at the 5 years mark as well, which can easily be $1200 – $1500 (I just paid $1000 for new tires for the Rav4 and we’re at the 5 year mark). Now these aren’t going to be *new* costs that I’m not used to from our existing vehicles, but they should still be factored in. I’d budget $500/year, or $5000 over the 10 years I’ll own the vehicle. Final Assessment So let’s re-assess the true cost of my dream MDX: MSRP                    $62,890 Taxes                       $7,546 Warranty                 $2,500 Finance Charge         $1094 Gas                        $10,000 Service Work            $5000 Grand Total           $89,030 So now I have a better idea of 10 year cost overall, and I’ve identified some concerns with local service availability. And there’s now much more to consider over the original $62,890 price tag. Tying This Back to Technology Solutions The process that we just went through is no different than what organizations do when considering implementing a new system, technology, or technology based solution, within their environments. It’s easy to tout the short term cost savings of particular product/platform/technology in a vacuum. But its when you consider the wider impact that the true cost comes into play. Let’s create a scenario: A company is not happy with its current data reporting suite. An employee suggests moving to an open source solution. The selling points are: - Because its open source its free - The organization would have access to the source code so they could alter it however they wished - It provided features not available with the current reporting suite At first this sounds great to the management and executive, but then they start asking some questions and uncover more information: - The OSS product is built on a technology not used anywhere within the organization - There are no vendors offering product support for the OSS product - The OSS product requires a specific server platform to operate on, one that’s not standard in the organization All of a sudden, the true cost of implementing this solution is starting to become clearer. The company might save money on licensing costs, but their training costs would increase significantly – developers would need to learn how to develop in the technology the OSS solution was built on, IT staff must learn how to set up and maintain a new server platform within their existing infrastructure, and if a problem was found there was no vendor to contact for support. The true cost of implementing a “free” OSS solution is actually spinning up a project to implement it within the organization – no small cost. And that’s just the short-term cost. Now the organization must ensure they maintain trained staff who can make changes to the OSS reporting solution and IT staff that will stay knowledgeable in the new server platform. If those skills are very niche, then higher labour costs could be incurred if those people are hard to find or if trained employees use that knowledge as leverage for higher pay. Maybe a vendor exists that will contract out support, but then there are those costs to consider as well. And let’s not forget end-user training – in our example, anyone that runs reports will need to be trained on how to use the new system. Here’s the Point We still tend to look at software in an “off the shelf” kind of way. It’s very easy to say “oh, this product is better than vendor x’s product – and its free because its OSS!” but the reality is that implementing any new technology within an organization has a cost regardless of the retail price of the product. Training, integration, support – these are real costs that impact an organization and span multiple departments. Whether you’re pitching an improved business process, a new system, or a new technology, you need to consider the bigger picture costs of implementation. What you define as success (in our example, having better reporting functionality) might not be what others define as success if implementing your solution causes them issues. A true enterprise solution needs to consider the entire enterprise.

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• General Policies and Procedures for Maintaining the Value of Data Assets

  Here is a general list for policies and procedures regarding maintaining the value of data assets. Data Backup Policies and Procedures Backups are very important when dealing with data because there is always the chance of losing data due to faulty hardware or a user activity. So the need for a strategic backup system should be mandatory for all companies. This being said, in the real world some companies that I have worked for do not really have a good data backup plan. Typically when companies tend to take this kind of approach in data backups usually the data is not really recoverable.  Unfortunately when companies do not regularly test their backup plans they get a false sense of security because they think that they are covered. However, I can tell you from personal and professional experience that a backup plan/system is never fully implemented until it is regularly tested prior to the time when it actually needs to be used. Disaster Recovery Plan Expanding on Backup Policies and Procedures, a company needs to also have a disaster recovery plan in order to protect its data in case of a catastrophic disaster.  Disaster recovery plans typically encompass how to restore all of a company’s data and infrastructure back to a restored operational status.  Most Disaster recovery plans also include time estimates on how long each step of the disaster recovery plan should take to be executed.  It is important to note that disaster recovery plans are never fully implemented until they have been tested just like backup plans. Disaster recovery plans should be tested regularly so that the business can be confident in not losing any or minimal data due to a catastrophic disaster. Firewall Policies and Content Filters One way companies can protect their data is by using a firewall to separate their internal network from the outside. Firewalls allow for enabling or disabling network access as data passes through it by applying various defined restrictions. Furthermore firewalls can also be used to prevent access from the internal network to the outside by these same factors. Common Firewall Restrictions Destination/Sender IP Address Destination/Sender Host Names Domain Names Network Ports Companies can also desire to restrict what their network user’s view on the internet through things like content filters. Content filters allow a company to track what webpages a person has accessed and can also restrict user’s access based on established rules set up in the content filter. This device and/or software can block access to domains or specific URLs based on a few factors. Common Content Filter Criteria Known malicious sites Specific Page Content Page Content Theme  Anti-Virus/Mal-ware Polices Fortunately, most companies utilize antivirus programs on all computers and servers for good reason, virus have been known to do the following: Corrupt/Invalidate Data, Destroy Data, and Steal Data. Anti-Virus applications are a great way to prevent any malicious application from being able to gain access to a company’s data.  However, anti-virus programs must be constantly updated because new viruses are always being created, and the anti-virus vendors need to distribute updates to their applications so that they can catch and remove them. Data Validation Policies and Procedures Data validation is very important to ensure that only accurate information is stored. The existence of invalid data can cause major problems when businesses attempt to use data for knowledge based decisions and for performance reporting. Data Scrubbing Policies and Procedures Data scrubbing is valuable to companies in one of two ways. The first can be used to clean data prior to being analyzed for report generation. The second is that it allows companies to remove things like personally Identifiable information from its data prior to transmit it between multiple environments or if the information is sent to an external location. An example of this can be seen with medical records in regards to HIPPA laws that prohibit the storage of specific personal and medical information. Additionally, I have professionally run in to a scenario where the Canadian government does not allow any Canadian’s personal information to be stored on a server not located in Canada. Encryption Practices The use of encryption is very valuable when a company needs to any personal information. This allows users with the appropriated access levels to view or confirm the existence or accuracy of data within a system by either decrypting the information or encrypting a piece of data and comparing it to the stored version.  Additionally, if for some unforeseen reason the data got in to the wrong hands then they would have to first decrypt the data before they could even be able to read it. Encryption just adds and additional layer of protection around data itself. Standard Normalization Practices The use of standard data normalization practices is very important when dealing with data because it can prevent allot of potential issues by eliminating the potential for unnecessary data duplication. Issues caused by data duplication include excess use of data storage, increased chance for invalidated data, and over use of data processing. Network and Database Security/Access Policies Every company has some form of network/data access policy even if they have none. These policies help secure data from being seen by inappropriate users along with preventing the data from being updated or deleted by users. In addition, without a good security policy there is a large potential for data to be corrupted by unassuming users or even stolen. Data Storage Policies Data storage polices are very important depending on how they are implemented especially when a company is trying to utilize them in conjunction with other policies like Data Backups. I have worked at companies where all network user folders are constantly backed up, and if a user wanted to ensure the existence of a piece of data in the form of a file then they had to store that file in their network folder. Conversely, I have also worked in places where when a user logs on or off of the network there entire user profile is backed up. Training Policies One of the biggest ways to prevent data loss and ensure that data will remain a company asset is through training. The practice of properly train employees on how to work with in systems that access data is crucial when trying to ensure a company’s data will remain an asset. Users need to be trained on how to manipulate a company’s data in order to perform their tasks to reduce the chances of invalidating data.

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• PASS Summit 2010 BI Workshop Feedbacks

  - by Davide Mauri

  As many other speakers already did, I’d like to share with the SQL Community the feedback of my PASS Summit 2010 Workshop. For those who were not there, my workshop was the “BI From A-Z” and the main objective of that workshop was to introduce people in the BI world not only from a technical point of view but insist a lot on the methodological and “engineered” approach. The will to put more engineering in the IT (and specially in the BI field) is something that has been growing stronger and stronger in me every day for of this last 5 years since is simply envy the fact that Airbus, Fincatieri, BMW (just to name a few) can create very complex machine “just” using putting people together and giving them some rules to follow (Of course this is an oversimplification but I think you get what I mean). The key point of engineering is that, after having defined the project blueprint, you have the possibility to give to a huge number of people, the rules to follow, the correct tools in order to implement the rules easily and semi-automatically and a way to measure the quality of the results. Could this be done in IT? Very big question, so my scope is now limited to BI. So that’s the main point of my workshop: and entry-level approach to BI (level was 200) in order to allow attendees to know the basics, to understand what tools they should use for which purpose and, above all, a set of rules and tools in order to make a BI solution scalable in terms of people working on it, while still maintaining a very good quality. All done not focusing only on the practice but explaining the theory behind to see how it can help *a lot* to build a correct solution despite the technology used to implement it. The idea is to reach a point where more then 70% of the work done to create a BI solution can be reused even if technologies changes. This is a very demanding challenge nowadays with the coming of Denali and its column-aligned storage and the shiny-new DAX language. As you may understand I was looking forward to get the feedback since you may have noticed that there’s a lot of “architectural” stuff in IT but really nothing on “engineering”. So how the session could be perceived by the attendees was really unknown to me. The feedback could also give a good indication if the need of more “engineering” is something I feel only by myself or if is something more broad. I’m very happy to be able to say that the overall score of 4.75 put my workshop in the TOP 20 session (on near 200 sessions)! Here’s the detailed evaluations: How would you rate the usefulness of the information presented in your day-to-day environment? 4.75 Answer:    # of Responses 3    1         4    12        5    42               How would you rate the Speaker's presentation skills? 4.80 Answer:    # of Responses 3 : 1         4 : 9         5 : 45               How would you rate the Speaker's knowledge of the subject? 4.95 Answer:    # of Responses 4 :  3         5 : 52               How would you rate the accuracy of the session title, description and experience level to the actual session? 4.75 Answer:    # of Responses 3 : 2         4 : 10         5 : 43               How would you rate the amount of time allocated to cover the topic/session? 4.44 Answer:    # of Responses 3 : 7         4 : 17        5 : 31               How would you rate the quality of the presentation materials? 4.62 Answer:    # of Responses 4 : 21        5 : 34 The comments where all very positive. Many of them asked for more time on the subject (or to shorten the very last topics). I’ll make treasure of these comments and will review the content accordingly. We’ll organize a two-day classes on this topic, where also more examples will be shown and some arguments will be explained more deeply. I’d just like to answer a comment that asks how much of what I shown is “universally applicable”. I can tell you that all of our BI project follow these rules and they’ve been applied to different markets (Insurance, Fashion, GDO) with different people and different teams and they allowed us to be “Adaptive” against the customer. The more the rules are well defined and the more there are tools that supports their implementations, the easier is to add new people to the project and to add or change solution features. Think of a car. How come that almost any mechanic can help you to fix a problem? Because they know what to expect. Because there a rules that allow them to identify the problem without having to discover each time how the car has been implemented build. And this is of course also true for car upgrades/improvements. Last but not least: thanks a lot to everyone for coming!

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• Data Source Connection Pool Sizing

  - by Steve Felts

  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:10.0pt; font-family:"Times New Roman","serif";} One of the most time-consuming procedures of a database application is establishing a connection. The connection pooling of the data source can be used to minimize this overhead.  That argues for using the data source instead of accessing the database driver directly. Configuring the size of the pool in the data source is somewhere between an art and science – this article will try to move it closer to science.  From the beginning, WLS data source has had an initial capacity and a maximum capacity configuration values.  When the system starts up and when it shrinks, initial capacity is used.  The pool can grow to maximum capacity.  Customers found that they might want to set the initial capacity to 0 (more on that later) but didn’t want the pool to shrink to 0.  In WLS 10.3.6, we added minimum capacity to specify the lower limit to which a pool will shrink.  If minimum capacity is not set, it defaults to the initial capacity for upward compatibility.   We also did some work on the shrinking in release 10.3.4 to reduce thrashing; the algorithm that used to shrink to the maximum of the currently used connections or the initial capacity (basically the unused connections were all released) was changed to shrink by half of the unused connections. The simple approach to sizing the pool is to set the initial/minimum capacity to the maximum capacity.  Doing this creates all connections at startup, avoiding creating connections on demand and the pool is stable.  However, there are a number of reasons not to take this simple approach. When WLS is booted, the deployment of the data source includes synchronously creating the connections.  The more connections that are configured in initial capacity, the longer the boot time for WLS (there have been several projects for parallel boot in WLS but none that are available).  Related to creating a lot of connections at boot time is the problem of logon storms (the database gets too much work at one time).   WLS has a solution for that by setting the login delay seconds on the pool but that also increases the boot time. There are a number of cases where it is desirable to set the initial capacity to 0.  By doing that, the overhead of creating connections is deferred out of the boot and the database doesn’t need to be available.  An application may not want WLS to automatically connect to the database until it is actually needed, such as for some code/warm failover configurations. There are a number of cases where minimum capacity should be less than maximum capacity.  Connections are generally expensive to keep around.  They cause state to be kept on both the client and the server, and the state on the backend may be heavy (for example, a process).  Depending on the vendor, connection usage may cost money.  If work load is not constant, then database connections can be freed up by shrinking the pool when connections are not in use.  When using Active GridLink, connections can be created as needed according to runtime load balancing (RLB) percentages instead of by connection load balancing (CLB) during data source deployment. Shrinking is an effective technique for clearing the pool when connections are not in use.  In addition to the obvious reason that there times where the workload is lighter,  there are some configurations where the database and/or firewall conspire to make long-unused or too-old connections no longer viable.  There are also some data source features where the connection has state and cannot be used again unless the state matches the request.  Examples of this are identity based pooling where the connection has a particular owner and XA affinity where the connection is associated with a particular RAC node.  At this point, WLS does not re-purpose (discard/replace) connections and shrinking is a way to get rid of the unused existing connection and get a new one with the correct state when needed. So far, the discussion has focused on the relationship of initial, minimum, and maximum capacity.  Computing the maximum size requires some knowledge about the application and the current number of simultaneously active users, web sessions, batch programs, or whatever access patterns are common.  The applications should be written to only reserve and close connections as needed but multiple statements, if needed, should be done in one reservation (don’t get/close more often than necessary).  This means that the size of the pool is likely to be significantly smaller then the number of users.   If possible, you can pick a size and see how it performs under simulated or real load.  There is a high-water mark statistic (ActiveConnectionsHighCount) that tracks the maximum connections concurrently used.  In general, you want the size to be big enough so that you never run out of connections but no bigger.   It will need to deal with spikes in usage, which is where shrinking after the spike is important.  Of course, the database capacity also has a big influence on the decision since it’s important not to overload the database machine.  Planning also needs to happen if you are running in a Multi-Data Source or Active GridLink configuration and expect that the remaining nodes will take over the connections when one of the nodes in the cluster goes down.  For XA affinity, additional headroom is also recommended.  In summary, setting initial and maximum capacity to be the same may be simple but there are many other factors that may be important in making the decision about sizing.

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• Complex event system for DungeonKeeper like game

  - by paul424

  I am working on opensource GPL3 game. http://opendungeons.sourceforge.net/ , new coders would be welcome. Now there's design question regarding Event System: We want to improve the game logic, that is program a new event system. I will just repost what's settled up already on http://forum.freegamedev.net/viewtopic.php?f=45&t=3033. From the discussion came the idea of the Publisher / Subscriber pattern + "domains": My current idea is to use the subscirbers / publishers model. Its similar to Observable pattern, but instead one subscribes to Events types, not Object's Events. For each Event would like to have both static and dynamic type. Static that is its's type would be resolved by belonging to the proper inherited class from Event. That is from Event we would have EventTile, EventCreature, EvenMapLoader, EventGameMap etc. From that there are of course subtypes like EventCreature would be EventKobold, EventKnight, EventTentacle etc. The listeners would collect the event from publishers, and send them subcribers , each of them would be a global singleton. The Listeners type hierachy would exactly mirror the type hierarchy of Events. In each constructor of Event type, the created instance would notify the proper listeners. That is when calling EventKnight the proper ctor would notify the Listeners : EventListener, CreatureLisener and KnightListener. The default action for an listner would be to notify all subscribers, but there would be some exceptions , like EventAttack would notify AttackListener which would dispatch event by the dynamic part ( that is the Creature pointer or hash). Any comments ? #include <vector> class Subscriber; class SubscriberAttack; class Event{ private: int foo; int bar; protected: // static std::vector<Publisher*> publishersList; static std::vector<Subscriber*> subscribersList; static std::vector<Event*> eventQueue; public: Event(){ eventQueue.push_back(this); } static int subscribe(Subscriber* ss); static int unsubscribe(Subscriber* ss); //static int reg_publisher(Publisher* pp); //static int unreg_publisher(Publisher* pp); }; // class Publisher{ // }; class Subscriber{ public: int (*newEvent) (Event* ee); Subscriber( ){ Event::subscribe(this); } Subscriber( int (*fp) (Event* ee) ):newEvent(fp){ Subscriber(); } ~Subscriber(){ Event::unsubscribe(this); } }; class EventAttack: Event{ private: int foo; int bar; protected: // static std::vector<Publisher*> publishersList; static std::vector<SubscriberAttack*> subscribersList; static std::vector<EventAttack*> eventQueue; public: EventAttack(){ eventQueue.push_back(this); } static int subscribe(SubscriberAttack* ss); static int unsubscribe(SubscriberAttack* ss); //static int reg_publisher(Publisher* pp); //static int unreg_publisher(Publisher* pp); }; class AttackSubscriber :Subscriber{ public: int (*newEvent) (EventAttack* ee); AttackSubscriber( ){ EventAttack::subscribe(this); } AttackSubscriber( int (*fp) (EventAttack* ee) ):newEventAttack(fp){ AttackSubscriber(); } ~AttackSubscriber(){ EventAttack::unsubscribe(this); } }; From that point, others wanted the Subject-Observer pattern, that is one would subscribe to all event types produced by particular object. That way it came out to add the domain system : Huh, to meet the ability to listen to particular game's object events, I though of introducing entity domains . Domains are trees, which nodes are labeled by unique names for each level. ( like the www addresses ). Each Entity wanting to participate in our event system ( that is be able to publish / produce events ) should at least now its domain name. That would end up in Player1/Room/Treasury/#24 or Player1/Creature/Kobold/#3 producing events. The subscriber picks some part of a tree. For example by specifiing subtree with the root in one of the nodes like Player1/Room/* ,would subscribe us to all Players1's room's event, and Player1/Creature/Kobold/#3 would subscribe to Players' third kobold's event. Does such event system make sense to you ? I have many implementation details to ask as well, but first let's start some general discussion. Note1: Notice that in the case of a fight between two creatues fight , the creature being attacked would have to throw an event, becuase it is HE/SHE/IT who have its domain address. So that would be BeingAttackedEvent() etc. I will edit that post if some other reflections on this would come out. Note2: the existing class hierarchy might be used to get the domains addresses being build in constructor . In a ctor you would just add + ."className" to domain address. If you are in a class'es hierarchy leaf constructor one might use nextID , hash or any other charactteristic, just to make the addresses distinguishable . Note3:subscribing to all entity's Events would require knowledge of all possible events produced by this entity . This could be done in one function call, but information on E produced would have to be handled for every Entity. SmartNote4 : Finding proper subscribers in a tree would be easy. One would start in particular Leaf for example Player1/Creature/Kobold/#3 and go up one parent a time , notifiying each Subscriber in a Node ie. : Player1/Creature/Kobold/* , Player1/Creature/* , Player1/* etc, , up to a root that is /* .<<<< Note5: The Event system was needed to have some way of incorporating Angelscript code into application. So the Event dispatcher was to be a gate to A-script functions. But it came out to this one.

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• How to decrypt an encrypted Apple iTunes iPhone backup?

  - by afit

  I've been asked by a number of unfortunate iPhone users to help them restore data from their iTunes backups. This is easy when they are unencrypted, but not when they are encrypted, whether or not the password is known. As such, I'm trying to figure out the encryption scheme used on mddata and mdinfo files when encrypted. I have no problems reading these files otherwise, and have built some robust C# libraries for doing so. (If you're able to help, I don't care which language you use. It's the principle I'm after here!) The Apple "iPhone OS Enterprise Deployment Guide" states that "Device backups can be stored in encrypted format by selecting the Encrypt iPhone Backup option in the device summary pane of iTunes. Files are encrypted using AES128 with a 256-bit key. The key is stored securely in the iPhone keychain." That's a pretty good clue, and there's some good info here on Stackoverflow on iPhone AES/Rijndael interoperability suggesting a keysize of 128 and CBC mode may be used. Aside from any other obfuscation, a key and initialisation vector (IV)/salt are required. One might assume that the key is a manipulation of the "backup password" that users are prompted to enter by iTunes and passed to "AppleMobileBackup.exe", padded in a fashion dictated by CBC. However, given the reference to the iPhone keychain, I wonder whether the "backup password" might not be used as a password on an X509 certificate or symmetric private key, and that the certificate or private key itself might be used as the key. (AES and the iTunes encrypt/decrypt process is symmetric.) The IV is another matter, and it could be a few things. Perhaps it's one of the keys hard-coded into iTunes, or into the devices themselves. Although Apple's comment above suggests the key is present on the device's keychain, I think this isn't that important. One can restore an encrypted backup to a different device, which suggests all information relevant to the decryption is present in the backup and iTunes configuration, and that anything solely on the device is irrelevant and replacable in this context. So where might be the key be? I've listed paths below from a Windows machine but it's much of a muchness whichever OS we use. The "\appdata\Roaming\Apple Computer\iTunes\itunesprefs.xml" contains a PList with a "Keychain" dict entry in it. The "\programdata\apple\Lockdown\09037027da8f4bdefdea97d706703ca034c88bab.plist" contains a PList with "DeviceCertificate", "HostCertificate", and "RootCertificate", all of which appear to be valid X509 certs. The same file also appears to contain asymmetric keys "RootPrivateKey" and "HostPrivateKey" (my reading suggests these might be PKCS #7-enveloped). Also, within each backup there are "AuthSignature" and "AuthData" values in the Manifest.plist file, although these appear to be rotated as each file gets incrementally backed up, suggested they're not that useful as a key, unless something really quite involved is being done. There's a lot of misleading stuff out there suggesting getting data from encrypted backups is easy. It's not, and to my knowledge it hasn't been done. Bypassing or disabling the backup encryption is another matter entirely, and is not what I'm looking to do. This isn't about hacking apart the iPhone or anything like that. All I'm after here is a means to extract data (photos, contacts, etc.) from encrypted iTunes backups as I can unencrypted ones. I've tried all sorts of permutations with the information I've put down above but got nowhere. I'd appreciate any thoughts or techniques I might have missed.

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• How to use BCDEdit to dual boot Windows installations?

  - by Ian Boyd

  What are the bcdedit commands necessary to setup dual boot between different installations of Windows?5 Background i recently installed Windows 8 onto a separate hard drive1. Now that Windows 8 in installed i want to dual-boot back to Windows 7. i have my two2 hard drives: So you can see that i have my two disks, with the partitions containing Windows: Windows 7: \\PhysicalDisk0 (partition 03) Windows 8: \\PhysicalDisk2 (partition 1) What i'm trying to figure out how is how to use bcdedit to instruct the thing that boots Windows that there is another Windows installation out there. Running bcdedit now, it shows current configuration: C:\WINDOWS\system32>bcdedit Windows Boot Manager -------------------- identifier {bootmgr} device partition=\Device\HarddiskVolume2 description Windows Boot Manager locale en-US inherit {globalsettings} integrityservices Enable default {current} resumeobject {ce153eb7-3786-11e2-87c0-e740e123299f} displayorder {current} toolsdisplayorder {memdiag} timeout 30 Windows Boot Loader ------------------- identifier {current} device partition=C: path \WINDOWS\system32\winload.exe description Windows 8 locale en-US inherit {bootloadersettings} recoverysequence {ce153eb9-3786-11e2-87c0-e740e123299f} integrityservices Enable recoveryenabled Yes allowedinmemorysettings 0x15000075 osdevice partition=C: systemroot \WINDOWS resumeobject {ce153eb7-3786-11e2-87c0-e740e123299f} nx OptIn bootmenupolicy Standard hypervisorlaunchtype Auto i cannot find any documentation on the difference between Windows Boot Manager and Windows Boot Loader. Documentation There is some documentation on Bcdedit: Technet: Command Line Reference - Bcdedit Technet: Windows Automated Installation Kit - BCDEdit Command Line Options Whitepaper - BCDEdit Commands for Boot Environment (Word Document) But they don't explain how edit the binary boot configuration data If i had to guess, i would think that a Windows Boot Manager instructs the BIOS what program it should run. That program would give the user a set of boot choices. That leaves Windows Boot Loader do be a particular boot choice, that represents a particular installation of Windows. If that is the case i would need to create a new Windows Boot Loader entry. This means i might want to use the /create parameter: /create Creates a new boot entry: bcdedit [/store filename] /create [id] /d description [/application apptype | /inherit [apptype] | /inherit DEVICE | /device] So i assume a syntax of: >bcdedit /create /d "The old Windows 7" /application osloader Where application can be one of the following types: Apptype Description BOOTSECTOR The boot sector application OSLOADER The Windows boot loader RESUME A resume application Unfortunately, the only documentation about osloader is "The Windows boot loader". i don't see how that can differentiate between Windows 8 on one hard drive, and Windows 7 on another. The other possible parameter when /create a boot loader is >bcdedit /create /D "Windows Vista" /device "The Quick Brown Fox" Unfortunately the documentation is missing for /device: /device Optional. If id is not set to a well-known identifier, the option that is used to specify the new boot entry as an additional device options entry. Since i did not set id to a well-known identifier, i must set /device to "the option that is used to specify the new boot entry as an additional device options entry". i know all those words; they're all English. But i have on idea what it is saying; those words in that order seem nonsensical. So i'm somewhat stymied. i don't want to be like Dan Stolts from Microsoft: I found no content that was particularly helpful when I hosed my machine by playing with BCDEdit. This post would have been ok if there was much more detail especially on the /set command OSDevice, etc. So once I got my machine fixed, I documented the solution and the information is here.... i mean, if a Microsoft guy can't even figure out how to use BCDEdit to edit his BCD, then what chance to i have? Bonus Reading BCDEdit Command-Line Options Bcdedit Server 2008 R2 or Windows 7 System Will NOT Boot After Making Changes To Boot Manager Using BCDEdit Visual BCD Editor4 Windows 7 and Windows 8 RTM Dual Boot Setup Footnotes 1 Since the Windows 8 installer would have damaged my Windows 7 install, i decided to unplug my "main" hard drive during the install. Which is a long-winded explanation of why the Windows 8 installer didn't detect the existing Windows 7 install. Normally the installer would have automatically created the required entries for dual-boot. Not that the reason i'm asking the question is important. 2 Really there's three drives, but the third is just bulk storage. The existence of a 3rd hard drive is irrelevant to the question. i only mention it in case someone wants to know why the screenshot has 3 hard drives when i only mention two. 3 i arbitrarily started numbering partitions at "zero"; not to imply that partitions are numbered starting at zero. i only mention partitions because i don't see how any boot-loader could do its job without knowing which partition, and which folder, an installation of Windows is located in. 4 i'm asking about BCDEdit. i tried Visual BCD Editor. It seems to be a visual BCD editor. That is to say that it's a GUI, but still uses the same terminology as BCDEdit, and requires the same knowledge that BCD doesn't document. 5 For simplicity sake we'll assume that all installation of Windows i want to dual-boot between are Windows Vista or later, making them all compatible with the BCDEdit and the binary boot loader. The alternative would require delving into the intricacies of the old ntloader. Nor am i asking about dual booting to Linux; or how to boot to a Virtual Hard Drive (vhd) image. Just modern versions of Windows on existing hard drives in the same machine. Note: You can ignore everything after the word Background. It's all pointless exposition to satisfy some people's need for "research effort" before they'll consider being helpful. Some people have even been known to summarily close questions unless there is research effort. Some people have been know to close questions if there is too much research effort. Some people close questions when i put the note saying that they can ignore everything after the Background out of spite. Some people are just grumpy.

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• Multi-level navigation controller on left-hand side of UISplitView with a small twist.

  - by user141146

  Hi. I'm trying make something similar to (but not exactly like) the email app found on the iPad. Specifically, I'd like to create a tab-based app, but each tab would present the user with a different UISplitView. Each UISplitView contains a Master and a Detail view (obviously). In each UISplitView I would like the Master to be a multi-level navigational controller where new UIViewControllers are pushed onto (or popped off of) the stack. This type of navigation within the UISplitView is where the application is similar to the native email app. To the best of my knowledge, the only place that has described a decent "splitviewcontroller inside of a uitabbarcontroller" is here: http://stackoverflow.com/questions/2475139/uisplitviewcontroller-in-a-tabbar-uitabbarcontroller and I've tried to follow the accepted answer. The accepted solution seems to work for me (i.e., I get a tab-bar controller that allows me to switch between different UISplitViews). The problem is that I don't know how to make the left-hand side of the UISplitView to be a multi-level navigation controller. Here is the code I used within my app delegate to create the initial "split view 'inside' of a tab bar controller" (it's pretty much as suggested in the aforementioned link). - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { NSMutableArray *tabArray = [NSMutableArray array]; NSMutableArray *array = [NSMutableArray array]; UISplitViewController *splitViewController = [[UISplitViewController alloc] init]; MainViewController *viewCont = [[MainViewController alloc] initWithNibName:@"MainViewController" bundle:nil]; [array addObject:viewCont]; [viewCont release]; viewCont = [[DetailViewController alloc] initWithNibName:@"DetailViewController" bundle:nil]; [array addObject:viewCont]; [viewCont release]; [splitViewController setViewControllers:array]; [tabArray addObject:splitViewController]; [splitViewController release]; array = [NSMutableArray array]; splitViewController = [[UISplitViewController alloc] init]; viewCont = [[Master2 alloc] initWithNibName:@"Master2" bundle:nil]; [array addObject:viewCont]; [viewCont release]; viewCont = [[Slave2 alloc] initWithNibName:@"Slave2" bundle:nil]; [array addObject:viewCont]; [viewCont release]; [splitViewController setViewControllers:array]; [tabArray addObject:splitViewController]; [splitViewController release]; // Add the tab bar controller's current view as a subview of the window [tabBarController setViewControllers:tabArray]; [window addSubview:tabBarController.view]; [window makeKeyAndVisible]; return YES; } the class MainViewController is a UIViewController that contains the following method: - (IBAction)push_me:(id)sender { M2 *m2 = [[[M2 alloc] initWithNibName:@"M2" bundle:nil] autorelease]; [self.navigationController pushViewController:m2 animated:YES]; } this method is attached (via interface builder) to a UIButton found within MainViewController.xib Obviously, the method above (push_me) is supposed to create a second UIViewController (called m2) and push m2 into view on the left-side of the split-view when the UIButton is pressed. And yet it does nothing when the button is pressed (even though I can tell that the method is called). Thoughts on where I'm going wrong? TIA!

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• Drools flow architecture, Drools flow events with AND join nodes

  - by Shoukry K

  I have been evaluating a number of frameworks including jBPM and Drools flow for my application requirements. Lots of the opinions seem to be inclined towards Drools flow as its more flexible, knowledge oriented, easier to integrate with business rules, etc.. The application is some sort of an Email Campaign manager , where different customers can sign in, prepare (design) and launch email campaigns. The application should be able to do the following : 1- Receive a list of email addresses, send emails to each of these addresses starting from a certain date and during a certain time interval of the day , do some custom actions, and then wait for reply emails. 2- If a reply email is received and depending on the response text of the email , and depending on the time the email was received certain actions need to happen, web service calls need to take place, and error handling for these calls. 3- The application will manage and run many and different campaigns (different customers and different flows for each customer) at any point of time. The first question is : Is Drools flow the way to go about this? My main concerns are scalability, suspending, resuming flows, and long wait, and flows management. As you see from the requirements : There is a scheduling part : Certain flows need to be run at a certain point in time, they need to get suspended and then resumed. For example start sending emails starting on Dec 1st 2010 and send emails only in the time interval between 08:00 and 17:00 GMT. By then it might be that all subscribers have been sent emails, but it might not be the case, the process needs to (resume) on Dec 2nd and send a second batch, however certain (users) already received emails and they should be able to (continue at different stages of the flow) There are long wait states : Days or even weeks , i need to persist, suspend / resume and terminate flows (manage flows) External Events : This is where i got stuck first, i tried to put together a simple flow (see attached screenshot) See image http://img46.imageshack.us/img46/9620/workflowwithevents.png , there is a start node , connected to an action node, connected to a join. An event node is connected to a second action node, which is connected to the join. The join is an AND join , after the join there is an action and the end node. Here is the sample code i am using to launch the flow : KnowledgeBuilder builder = KnowledgeBuilderFactory .newKnowledgeBuilder(); builder.add(ResourceFactory.newClassPathResource("campaign.rf", CampaignsDroolsPoc.class), ResourceType.DRF); if (builder.hasErrors()) { KnowledgeBuilderErrors errors = builder.getErrors(); Iterator<KnowledgeBuilderError> iterator = errors.iterator(); while (iterator.hasNext()) { System.out.println(iterator.next().toString()); } } KnowledgeBase base = KnowledgeBaseFactory.newKnowledgeBase(); base.addKnowledgePackages(builder.getKnowledgePackages()); final StatefulKnowledgeSession ksession = base .newStatefulKnowledgeSession(); // KnowledgeRuntimeLoggerFactory.newConsoleLogger(ksession); ksession.getWorkItemManager().registerWorkItemHandler("Log", new SendSMSWorkItemHandler()); ProcessInstance startProcess = ksession.startProcess("flow"); System.out.println("Signaling event"); startProcess.signalEvent("ev1", "ev1"); System.out.println("Signaled"); ksession.fireUntilHalt(); I am noticing that the event get triggered, the action node connected to the event gets triggered, however things seem to get stuck at the join. The flow does not continue past the AND join and the flow seems to get stuck. The action following the node does not get triggered. I also went through the drools flow documentation , and all the example codes, however i didn't find anything there. In addition any hints about the way to go about architecting the solution, and implementing it would be great.

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• Is it possible to specify a generic constraint for a type parameter to be convertible FROM another t

  - by fostandy

  Suppose I write a library with the following: public class Bar { /* ... */ } public class SomeWeirdClass<T> where T : ??? { public T BarMaker(Bar b) { // ... play with b T t = (T)b return (T) b; } } Later, I expect users to use my library by defining their own types which are convertible to Bar and using the SomeWeirdClass 'factory'. public class Foo { public static explicit operator Foo(Bar f) { return new Bar(); } } public class Demo { public static void demo() { Bar b = new Bar(); SomeWeirdClass<Foo> weird = new SomeWeirdClass<Foo>(); Foo f = weird.BarMaker(b); } } this will compile if i set where T : Foo but the problem is that I don't know about Foo at the library's compile time, and I actually want something more like where T : some class that can be instantiated, given a Bar Is this possible? From my limited knowledge it does not seem to be, but the ingenuity of the .NET framework and its users always surprises me... This may or not be related to the idea of static interface methods - at least, I can see the value in being able to specify the presence of factory methods to create objects (similar to the same way that you can already perform where T : new()) edit: Solution - thanks to Nick and bzIm - For other readers I'll provide a completed solution as I understand it: edit2: This solution requires Foo to expose a public default constructor. For an even stupider better solution that does not require this see the very bottom of this post. public class Bar {} public class SomeWeirdClass<T> where T : IConvertibleFromBar<T>, new() { public T BarMaker(Bar b) { T t = new T(); t.Convert(b); return t; } } public interface IConvertibleFromBar<T> { T Convert(Bar b); } public class Foo : IConvertibleFromBar<Foo> { public static explicit operator Foo(Bar f) { return null; } public Foo Convert(Bar b) { return (Foo) b; } } public class Demo { public static void demo() { Bar b = new Bar(); SomeWeirdClass<Foo> weird = new SomeWeirdClass<Foo>(); Foo f = weird.BarMaker(b); } } edit2: Solution 2: Create a type convertor factory to use: #region library defined code public class Bar {} public class SomeWeirdClass<T, TFactory> where TFactory : IConvertorFactory<Bar, T>, new() { private static TFactory convertor = new TFactory(); public T BarMaker(Bar b) { return convertor.Convert(b); } } public interface IConvertorFactory<TFrom, TTo> { TTo Convert(TFrom from); } #endregion #region user defined code public class BarToFooConvertor : IConvertorFactory<Bar, Foo> { public Foo Convert(Bar from) { return (Foo) from; } } public class Foo { public Foo(int a) {} public static explicit operator Foo(Bar f) { return null; } public Foo Convert(Bar b) { return (Foo) b; } } #endregion public class Demo { public static void demo() { Bar b = new Bar(); SomeWeirdClass<Foo, BarToFooConvertor> weird = new SomeWeirdClass<Foo, BarToFooConvertor>(); Foo f = weird.BarMaker(b); } }

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• Is it possible to specify a generic constraint for a type parameter to be convertible FROM another t

  - by fostandy

  Suppose I write a library with the following: public class Bar { /* ... */ } public class SomeWeirdClass<T> where T : ??? { public T BarMaker(Bar b) { // ... play with b T t = (T)b return (T) b; } } Later, I expect users to use my library by defining their own types which are convertible to Bar and using the SomeWeirdClass 'factory'. public class Foo { public static explicit operator Foo(Bar f) { return new Bar(); } } public class Demo { public static void demo() { Bar b = new Bar(); SomeWeirdClass<Foo> weird = new SomeWeirdClass<Foo>(); Foo f = weird.BarMaker(b); } } this will compile if i set where T : Foo but the problem is that I don't know about Foo at the library's compile time, and I actually want something more like where T : some class that can be instantiated, given a Bar Is this possible? From my limited knowledge it does not seem to be, but the ingenuity of the .NET framework and its users always surprises me... This may or not be related to the idea of static interface methods - at least, I can see the value in being able to specify the presence of factory methods to create objects (similar to the same way that you can already perform where T : new()) edit: Solution - thanks to Nick and bzIm - For other readers I'll provide a completed solution as I understand it: edit2: This solution requires Foo to expose a public default constructor. For an even stupider better solution that does not require this see the very bottom of this post. public class Bar {} public class SomeWeirdClass<T> where T : IConvertibleFromBar<T>, new() { public T BarMaker(Bar b) { T t = new T(); t.Convert(b); return t; } } public interface IConvertibleFromBar<T> { T Convert(Bar b); } public class Foo : IConvertibleFromBar<Foo> { public static explicit operator Foo(Bar f) { return null; } public Foo Convert(Bar b) { return (Foo) b; } } public class Demo { public static void demo() { Bar b = new Bar(); SomeWeirdClass<Foo> weird = new SomeWeirdClass<Foo>(); Foo f = weird.BarMaker(b); } } edit2: Solution 2: Create a type convertor factory to use: #region library defined code public class Bar {} public class SomeWeirdClass<T, TFactory> where TFactory : IConvertorFactory<Bar, T>, new() { private static TFactory convertor = new TFactory(); public T BarMaker(Bar b) { return convertor.Convert(b); } } public interface IConvertorFactory<TFrom, TTo> { TTo Convert(TFrom from); } #endregion #region user defined code public class BarToFooConvertor : IConvertorFactory<Bar, Foo> { public Foo Convert(Bar from) { return (Foo) from; } } public class Foo { public Foo(int a) {} public static explicit operator Foo(Bar f) { return null; } public Foo Convert(Bar b) { return (Foo) b; } } #endregion public class Demo { public static void demo() { Bar b = new Bar(); SomeWeirdClass<Foo, BarToFooConvertor> weird = new SomeWeirdClass<Foo, BarToFooConvertor>(); Foo f = weird.BarMaker(b); } }

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• On REST: WADL or not IDL, is the following approach right ?

  - by redben

  This question is a bit long, please bear with me. In REST, i think we should not need WADL or any IDL. But rather something that would implicitly cover its concept. The way I think about it is when we (humans) surf the Web, when we go to a web site for the first time, we don't know what services it provides. You discover those on the html home page (or a sitemap page in a help section) or maybe just the main menu on the home page. If you make an analogy, the homepage or site map to us humans is what WSDL is to WS-* or what WADL could be to a REST service. Only that its just like any other html content. I think that in REST the following is a good way to do things, respecting the HATEOS paradigm. Have a top level (or default) resource that lists links to your other resources. For a library example, say RestLibrary.com/ it could be something like: <root xmlns:lib="http://librarystandards.com/libraryml"> <resource class="lib:book"> <link type="application/vnd.libraryml+xml" template="mylib.com/book/{isbn}" /> <link type="application/vnd.libraryml+xml" rel="add" href="mylib.com/book" method="POST" /> <link type="application/vnd.libraryml+xml" rel="update" template="mylib.com/book/{isbn}" method="PUT" /> </resource> <resource class="lib:bookList"> <link template="mylib.com/book?keywords={keywords}" type="application/vnd.openlibrary+xml" rel="search" /> </resource> </root> Note that it is assumed that the media type "application/vnd.libraryml+xml" is a defined standard or (may be just proprietary vocabulary) named libraryml. Also, the client should be able to understand this "homepage" resource (elements root, resource and link). This is the part that could be used instead of WADL : an Abstract vocabulary that should be understandable by any client. You could use an existing standard like Atom for example. But the main idea is to have an abstract vocabulary understandable by any client. Why not WADL then ? well wadl is only for service discovery. The idea here is to have an light abstract vocabulary that would serve as a base for hypermedia. A "root" vocabulary. Like in owl we have owl:thing...etc Now if the client knows the "libraryml" standard it can follow the links to the things it understands (after parsing the media type properties and xmlns). If not, it just won't. When i can't understand how to deal with something in REST architecture i tend to see how we Humans do it in the Web. In the Web, we have the Generic language that is HTML that enables site builders to deliver any specific content, regardless of its meaning to the client (the user), Browsers understand HTML but not the "meaning" of its content. It is the user that understands the (domain specific) content. If i go to say QuantumPhysics.org, my browser can render the home page (it is just html after all) and i can read the home page. If i understand quantum then fine i can continue browsing. If i don't i just get out (unless i want to learn the hardway :) ) In the RetsLibrary.com example the client app is just like me+my browser on QuantumPhysics.org. the media type "application/vnd.libraryml+xml" is quantum physics (knowledge). http is http in both examples. Now HTML of QuantumPhysics.org is in RestLibrary.com is XML + that tiny little abstract vocabulary (root resource and link, that you could replace with something like Atom). So does this approach have any value ? don't we need a root tiny hyper-vocabulary so we can succeed with hypermedia and the "initial URI" concept ? edit Yeah why not RDF as the root vocabulary !

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• Setting Session Variable from UpdatePanel

  - by Gavin

  I am using ASP.NET 2.0 AJAX Extensions 1.0 with the version v1.0.20229 of the AJAX Control Toolkit (which to my knowledge is the latest for .NET 2.0/Visual Studio 2005). My web page (aspx) has a DropDownList control on an UpdatePanel. In the handler for the DropDownList's SelectedIndexChanged event I attempt to set a session variable. The first time the event is fired, I get a Sys.WebForms.PageRequestManagerParserErrorException: "The message received from the server could not be parsed". If I continue, subsequent SelectedIndexChanged's are handled successfully. I have stumbled upon a solution whereby if I initialise the session variable in my Page_Load (so the event handler is just setting the value of a session variable that already exists as opposed to creating a new one) the problem goes away. I'm happy to do this, but I'm curious as to exactly what the underlying cause is. Can anyone explain? (My suspicion is that setting the session variable receives a response from the server which is then returned to the 'caller', but it's not the sort of response it knows how to deal with causing the exception?) EDIT: I reproduced the problem in a seperate little project: Default.aspx <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="SessionTest._Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server"> <title>Untitled Page</title> </head> <body> <form id="form1" runat="server"> <asp:ScriptManager ID="ScriptManager1" runat="server" /> <div> <asp:UpdatePanel id="upCategorySelector" runat="server"> <ContentTemplate> Category: <asp:DropDownList ID="ddlCategory" runat="server" AutoPostBack="true" OnSelectedIndexChanged="ddlCategories_SelectedIndexChanged"> <asp:ListItem>Item 1</asp:ListItem> <asp:ListItem>Item 2</asp:ListItem> <asp:ListItem>Item 3</asp:ListItem> </asp:DropDownList> </ContentTemplate> </asp:UpdatePanel> </div> </form> </body> </html> Default.aspx.cs using System; using System.Data; using System.Configuration; using System.Collections; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; namespace SessionTest { public partial class _Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { // If I do this, the exception does not occur. if (Session["key"] == null) Session.Add("key", 0); } protected void ddlCategories_SelectedIndexChanged(object sender, EventArgs e) { // If Session["key"] has not been created, setting it from // the async call causes the excaption Session.Add("key", ((DropDownList)sender).SelectedValue); } } }

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• howto only tunnel specific hosts route through openvpn client on tomato

  - by kcome

  I am relatively newbie in networking world although I did coding and know some sysadmin background for a long time. and here I'm only one step from my destination. The whole picture is : at home I use one LinkSys E3000 as the gateway(don't know yet if this is it's name), wireless AP and no other routing/switching devices. It serves 1 PC and 1 Mac with LAN, 1 Mac Mini + 1 iPad + 2 smartphones with WIFI. My goal is use an openvpn client on the E3000 (with tomato firmware) and make my iPad and smartphone's all WiFi traffic through it, and other devices route remain the same non-openvpn route. So far I'm able to connect openvpn client on E3000 to an openvpn server, tunnel all my devices' all traffic through that openvpn connection. What's left is howto selectively route by source IP (at least in my guessing) to the tunnel while don't bother others. I had learned some 'iptables' and 'route' in past few days however without much luck, so here comes my question. Here are some info which will help you get the structure. ifconfig -a output, some useless lines striped, and in the web interface C0:C1:C0:1A:E0:28 is WAN, C0:C1:C0:1A:E0:27 is LAN, C0:C1:C0:1A:E0:29 is 2.4G wifi AP, C0:C1:C0:1A:E0:2A is 5G wifi AP. root@router:/tmp/home/root# ifconfig -a br0 Link encap:Ethernet HWaddr C0:C1:C0:1A:E0:27 inet addr:192.168.1.1 Bcast:192.168.1.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 eth0 Link encap:Ethernet HWaddr C0:C1:C0:1A:E0:27 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 eth1 Link encap:Ethernet HWaddr C0:C1:C0:1A:E0:29 UP BROADCAST RUNNING ALLMULTI MULTICAST MTU:1500 Metric:1 eth2 Link encap:Ethernet HWaddr C0:C1:C0:1A:E0:2A UP BROADCAST RUNNING ALLMULTI MULTICAST MTU:1500 Metric:1 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host ppp0 Link encap:Point-to-Point Protocol inet addr:172.200.1.43 P-t-P:172.200.0.1 Mask:255.255.255.255 UP POINTOPOINT RUNNING MULTICAST MTU:1480 Metric:1 vlan1 Link encap:Ethernet HWaddr C0:C1:C0:1A:E0:27 UP BROADCAST RUNNING ALLMULTI MULTICAST MTU:1500 Metric:1 vlan2 Link encap:Ethernet HWaddr C0:C1:C0:1A:E0:28 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 wl0.1 Link encap:Ethernet HWaddr C0:C1:C0:1A:E0:29 BROADCAST MULTICAST MTU:1500 Metric:1 brctl show output root@router:/tmp/home/root# brctl show bridge name bridge id STP enabled interfaces br0 8000.c0c1c01ae027 no vlan1 eth1 eth2 before openvpn route-up script root@router:/tmp/home/root# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 172.200.0.1 0.0.0.0 255.255.255.255 UH 0 0 0 ppp0 192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 br0 127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo 0.0.0.0 172.200.0.1 0.0.0.0 UG 0 0 0 ppp0 openvpn server push PUSH: Received control message: 'PUSH_REPLY,redirect-gateway,dhcp-option DNS 8.8.8.8,route 172.20.0.1,topology net30,ping 10,ping-restart 120,ifconfig 172.20.0.6 172.20.0.5' openvpn's stock route-up script Apr 24 14:52:06 router daemon.notice openvpn[1768]: /sbin/ifconfig tun11 172.20.0.6 pointopoint 172.20.0.5 mtu 1500 Apr 24 14:52:08 router daemon.notice openvpn[1768]: /sbin/route add -net 72.14.177.29 netmask 255.255.255.255 gw 172.200.0.1 Apr 24 14:52:08 router daemon.notice openvpn[1768]: /sbin/route add -net 0.0.0.0 netmask 128.0.0.0 gw 172.20.0.5 Apr 24 14:52:08 router daemon.notice openvpn[1768]: /sbin/route add -net 128.0.0.0 netmask 128.0.0.0 gw 172.20.0.5 Apr 24 14:52:08 router daemon.notice openvpn[1768]: /sbin/route add -net 172.20.0.1 netmask 255.255.255.255 gw 172.20.0.5 route after openvpn root@router:/tmp/home/root# route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 172.20.0.5 0.0.0.0 255.255.255.255 UH 0 0 0 tun11 72.14.177.29 172.200.0.1 255.255.255.255 UGH 0 0 0 ppp0 172.200.0.1 0.0.0.0 255.255.255.255 UH 0 0 0 ppp0 172.20.0.1 172.20.0.5 255.255.255.255 UGH 0 0 0 tun11 192.168.1.0 0.0.0.0 255.255.255.0 U 0 0 0 br0 127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo 0.0.0.0 172.20.0.5 128.0.0.0 UG 0 0 0 tun11 128.0.0.0 172.20.0.5 128.0.0.0 UG 0 0 0 tun11 0.0.0.0 172.200.0.1 0.0.0.0 UG 0 0 0 ppp0 something I had noticed and tried: * on the web interface of openvpn client there is an option "Create NAT on tunnel", if i check this, there is the following script (probably executed after openvpn connection established) root@router:/tmp/home/root# cat /tmp/etc/openvpn/fw/client1-fw.sh #!/bin/sh iptables -I INPUT -i tun11 -j ACCEPT iptables -I FORWARD -i tun11 -j ACCEPT iptables -t nat -I POSTROUTING -s 192.168.1.0/255.255.255.0 -o tun11 -j MASQUERADE if i uncheck this option, the last line will not appear. Then I guess probably the my issue will be solved by iptables and NAT related commands, I just haven't got enough knowledge to figure them out. I tried run iptables -t nat -I POSTROUTING -s 192.168.1.6 -o tun11 -j MASQUERADE manually after openvpn connected (192.168.1.6 is the ip address of my iPad), then my iPad get internet with openvpn tunnel, however all other devices can't reach internet. in case if needed, here is the iptables about NAT root@router:/tmp/home/root# iptables -t nat -L -n Chain PREROUTING (policy ACCEPT) target prot opt source destination DROP all -- 0.0.0.0/0 192.168.1.0/24 WANPREROUTING all -- 0.0.0.0/0 172.200.1.43 upnp all -- 0.0.0.0/0 172.200.1.43 Chain POSTROUTING (policy ACCEPT) target prot opt source destination MASQUERADE all -- 0.0.0.0/0 0.0.0.0/0 SNAT all -- 192.168.1.0/24 192.168.1.0/24 to:192.168.1.1 Chain OUTPUT (policy ACCEPT) target prot opt source destination Chain WANPREROUTING (1 references) target prot opt source destination DNAT icmp -- 0.0.0.0/0 0.0.0.0/0 to:192.168.1.1 Chain upnp (1 references) target prot opt source destination DNAT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:5353 to:192.168.1.3:5353 Thanks in advance for helping and read this so much, I hope i made every info you need to give a help :)

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• Poor upload/download speed on 2 x ADSL lines into a Cisco 2621XM

  - by 2020mobile

  Hi, Sorry never been on this site before so I apologise if not the right section or even forum. I have users complaining of very slow internetn connectivity on site and have checked with our ISP who have said that the line is testing at 8mb. We have 2 x BT lines that have our ISP broadand on them. Both lines go into a Cisco 2600 series router that then has a PIX firewall off that. Connectivity is successful just gone really slow and unable to download anything. Config is below: version 12.3 no service pad service tcp-keepalives-in service tcp-keepalives-out service timestamps debug datetime msec service timestamps log datetime msec service password-encryption ! hostname ROUTER-ADSL-INTERNET ! logging buffered 16384 informational enable secret xxx enable password xxx ! username xxx username xxx clock summer-time UK recurring last Sun Mar 1:00 last Sun Oct 1:00 aaa new-model ! ! aaa authentication login default local aaa authorization exec default local aaa session-id common ip subnet-zero no ip source-route ! ! ! ip audit notify log ip audit po max-events 100 no ip bootp server ip name-server 213.208.106.212 no mpls ldp logging neighbor-changes no ftp-server write-enable ! ! ! ! ! ! ! ! ! ! no voice hpi capture buffer no voice hpi capture destination ! ! ! ! ! ! ! ! interface ATM0/0 description 01270 111111 no ip address no atm ilmi-keepalive pvc 0/38 encapsulation aal5mux ppp dialer dialer pool-member 1 ! dsl operating-mode auto ! interface FastEthernet0/0 ip address 82.133.32.9 255.255.255.248 shutdown speed 100 full-duplex no cdp enable ! interface ATM0/1 description 01270 222222 no ip address no atm ilmi-keepalive pvc 0/38 encapsulation aal5mux ppp dialer dialer pool-member 1 ! dsl operating-mode auto ! interface FastEthernet0/1 ip address 217.146.115.49 255.255.255.240 duplex auto speed auto no cdp enable ! interface Dialer0 ip address 217.146.115.250 255.255.255.248 encapsulation ppp dialer pool 1 dialer-group 1 ppp authentication chap callin ppp chap hostname [email protected] ppp chap password 7 xxxxx ppp multilink ! ip classless ip route 0.0.0.0 0.0.0.0 Dialer0 ! no ip http server no ip http secure-server ! no logging trap access-list 10 permit 217.146.115.50 access-list 10 permit 82.133.32.10 access-list 10 deny any access-list 22 permit 217.146.115.50 access-list 22 permit 217.206.239.86 access-list 22 permit 82.133.32.10 access-list 22 deny any dialer-list 1 protocol ip permit no cdp run ! ! snmp-server community xxxxxx RO 10 snmp-server enable traps tty radius-server authorization permit missing Service-Type ! ! ! ! ! ! line con 0 exec-timeout 5 0 password 7 xxxxxx line aux 0 no exec line vty 0 4 access-class 22 in exec-timeout 5 0 password 7 xxxxxx transport input telnet ssh transport output none line vty 5 15 password 7 xxxxxx transport input telnet ssh ! ntp clock-period 17180095 ntp server 130.88.200.98 ! ! end Now my knowledge is very limited but ISP have said that while the lines are bonded each needs a seperate login as they've recently changed their L2TP router and that enforces the use of seperate logins - when the lines were configured we were given two logins. So, my question is what changes do I need to make to the config in order to get this working? it was ok before their change and I do have another login :- 01270 111111 - [email protected] 01270 222222 - [email protected] Apologies for the long email and thanks for taking the time to read it. Any more info I can provide please let me know. Thanks,

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• How do you automap List<float> or float[] with Fluent NHibernate?

  - by Tom Bushell

  Having successfully gotten a sample program working, I'm now starting to do Real Work with Fluent NHibernate - trying to use Automapping on my project's class heirarchy. It's a scientific instrumentation application, and the classes I'm mapping have several properties that are arrays of floats e.g. private float[] _rawY; public virtual float[] RawY { get { return _rawY; } set { _rawY = value; } } These arrays can contain a maximum of 500 values. I didn't expect Automapping to work on arrays, but tried it anyway, with some success at first. Each array was auto mapped to a BLOB (using SQLite), which seemed like a viable solution. The first problem came when I tried to call SaveOrUpdate on the objects containing the arrays - I got "No persister for float[]" exceptions. So my next thought was to convert all my arrays into ILists e.g. public virtual IList<float> RawY { get; set; } But now I get: NHibernate.MappingException: Association references unmapped class: System.Single Since Automapping can deal with lists of complex objects, it never occured to me it would not be able to map lists of basic types. But after doing some Googling for a solution, this seems to be the case. Some people seem to have solved the problem, but the sample code I saw requires more knowledge of NHibernate than I have right now - I didn't understand it. Questions: 1. How can I make this work with Automapping? 2. Also, is it better to use arrays or lists for this application? I can modify my app to use either if necessary (though I prefer lists). Edit: I've studied the code in Mapping Collection of Strings, and I see there is test code in the source that sets up an IList of strings, e.g. public virtual IList<string> ListOfSimpleChildren { get; set; } [Test] public void CanSetAsElement() { new MappingTester<OneToManyTarget>() .ForMapping(m => m.HasMany(x => x.ListOfSimpleChildren).Element("columnName")) .Element("class/bag/element").Exists(); } so this must be possible using pure Automapping, but I've had zero luck getting anything to work, probably because I don't have the requisite knowlege of manually mapping with NHibernate. Starting to think I'm going to have to hack this (by encoding the array of floats as a single string, or creating a class that contains a single float which I then aggregate into my lists), unless someone can tell me how to do it properly. End Edit Here's my CreateSessionFactory method, if that helps formulate a reply... private static ISessionFactory CreateSessionFactory() { ISessionFactory sessionFactory = null; const string autoMapExportDir = "AutoMapExport"; if( !Directory.Exists(autoMapExportDir) ) Directory.CreateDirectory(autoMapExportDir); try { var autoPersistenceModel = AutoMap.AssemblyOf<DlsAppOverlordExportRunData>() .Where(t => t.Namespace == "DlsAppAutomapped") .Conventions.Add( DefaultCascade.All() ) ; sessionFactory = Fluently.Configure() .Database(SQLiteConfiguration.Standard .UsingFile(DbFile) .ShowSql() ) .Mappings(m => m.AutoMappings.Add(autoPersistenceModel) .ExportTo(autoMapExportDir) ) .ExposeConfiguration(BuildSchema) .BuildSessionFactory() ; } catch (Exception e) { Debug.WriteLine(e); } return sessionFactory; }

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• Modern Java alternatives

  - by Ralph

  I'm not sure if stackoverflow is the best forum for this discussion. I have been a Java developer for 14 years and have written an enterprise-level (~500,000 line) Swing application that uses most of the standard library APIs. Recently, I have become disappointed with the progress that the language has made to "modernize" itself, and am looking for an alternative for ongoing development. I have considered moving to the .NET platform, but I have issues with using something the only runs well in Windows (I know about Mono, but that is still far behind Microsoft). I also plan on buying a new Macbook Pro as soon as Apple releases their new rumored Arrandale-based machines and want to develop in an environment that will feel "at home" in Unix/Linux. I have considered using Python or Ruby, but the standard Java library is arguably the largest of any modern language. In JVM-based languages, I looked at Groovy, but am disappointed with its performance. Rumor has it that with the soon-to-be released JDK7, with its InvokeDynamic instruction, this will improve, but I don't know how much. Groovy is also not truly a functional language, although it provides closures and some of the "functional" features on collections. It does not embrace immutability. I have narrowed my search down to two JVM-based alternatives: Scala and Clojure. Each has its strengths and weaknesses. I am looking for the stackoverflow readerships' opinions. I am not an expert at either of these languages; I have read 2 1/2 books on Scala and am currently reading Stu Halloway's book on Clojure. Scala is strongly statically typed. I know the dynamic language folks claim that static typing is a crutch for not doing unit testing, but it does provide a mechanism for compile-time location of a whole class of errors. Scala is more concise than Java, but not as much as Clojure. Scala's inter-operation with Java seems to be better than Clojure's, in that most Java operations are easier to do in Scala than in Clojure. For example, I can find no way in Clojure to create a non-static initialization block in a class derived from a Java superclass. For example, I like the Apache commons CLI library for command line argument parsing. In Java and Scala, I can create a new Options object and add Option items to it in an initialization block as follows (Java code): final Options options = new Options() { { addOption(new Option("?", "help", false, "Show this usage information"); // other options } }; I can't figure out how to the same thing in Clojure (except by using (doit...)), although that may reflect my lack of knowledge of the language. Clojure's collections are optimized for immutability. They rarely require copy-on-write semantics. I don't know if Scala's immutable collections are implemented using similar algorithms, but Rich Hickey (Clojure's inventor) goes out of his way to explain how that language's data structures are efficient. Clojure was designed from the beginning for concurrency (as was Scala) and with modern multi-core processors, concurrency takes on more importance, but I occasionally need to write simple non-concurrent utilities, and Scala code probably runs a little faster for these applications since it discourages, but does not prohibit, "simple" mutability. One could argue that one-off utilities do not have to be super-fast, but sometimes they do tasks that take hours or days to complete. I know that there is no right answer to this "question", but I thought I would open it up for discussion. If anyone has a suggestion for another JVM-based language that can be used for enterprise level development, please list it. Also, it is not my intent to start a flame war. Thanks, Ralph

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• Error when pushing to Heroku - StatementInvalid - Ruby on Rails

  - by bgadoci

  I am trying to deploy my first rails app to Heroku and seem to be having a problem. After git push heroku master I get an error saying that relation "tags does not exist. I understand that without knowledge of my application it will be hard to help but I am wondering if someone can point me in the right direction. I have checked the schema.rb file and also been over all my migrations and there doesn't seem to be a problem there. The error message lead me to believe that I left something out of my routes.rb file but can't seem to find anything there either. Perhaps just some help deciphering this message. Processing PostsController#index (for 99.7.50.140 at 2010-04-21 12:28:59) [GET] ActiveRecord::StatementInvalid (PGError: ERROR: relation "tags" does not exist : SELECT a.attname, format_type(a.atttypid, a.atttypmod), d.adsrc, a.attnotnull FROM pg_attribute a LEFT JOIN pg_attrdef d ON a.attrelid = d.adrelid AND a.attnum = d.adnum WHERE a.attrelid = '"tags"'::regclass AND a.attnum > 0 AND NOT a.attisdropped ORDER BY a.attnum ): app/controllers/posts_controller.rb:9:in `index' /home/heroku_rack/lib/static_assets.rb:9:in `call' /home/heroku_rack/lib/last_access.rb:25:in `call' /home/heroku_rack/lib/date_header.rb:14:in `call' thin (1.0.1) lib/thin/connection.rb:80:in `pre_process' thin (1.0.1) lib/thin/connection.rb:78:in `catch' thin (1.0.1) lib/thin/connection.rb:78:in `pre_process' thin (1.0.1) lib/thin/connection.rb:57:in `process' thin (1.0.1) lib/thin/connection.rb:42:in `receive_data' eventmachine (0.12.6) lib/eventmachine.rb:240:in `run_machine' eventmachine (0.12.6) lib/eventmachine.rb:240:in `run' thin (1.0.1) lib/thin/backends/base.rb:57:in `start' thin (1.0.1) lib/thin/server.rb:150:in `start' thin (1.0.1) lib/thin/controllers/controller.rb:80:in `start' thin (1.0.1) lib/thin/runner.rb:173:in `send' thin (1.0.1) lib/thin/runner.rb:173:in `run_command' thin (1.0.1) lib/thin/runner.rb:139:in `run!' thin (1.0.1) bin/thin:6 /usr/local/bin/thin:20:in `load' /usr/local/bin/thin:20 Also, here is my routes.rb file if that helps at all. ActionController::Routing::Routes.draw do |map| map.resources :ugtags map.resources :wysihat_files map.resources :users map.resources :votes map.resources :votes, :belongs_to => :user map.resources :tags, :belongs_to => :user map.resources :ugtags, :belongs_to => :user map.resources :posts, :collection => {:auto_complete_for_tag_tag_name => :get } map.resources :posts, :sessions map.resources :posts, :has_many => :comments map.resources :posts, :has_many => :tags map.resources :posts, :has_many => :ugtags map.resources :posts, :has_many => :votes map.resources :posts, :belongs_to => :user map.resources :tags, :collection => {:auto_complete_for_tag_tag_name => :get } map.resources :ugtags, :collection => {:auto_complete_for_ugtag_ugctag_name => :get } map.login 'login', :controller => 'sessions', :action => 'new' map.logout 'logout', :controller => 'sessions', :action => 'destroy' map.root :controller => "posts" map.connect ':controller/:action/:id' map.connect ':controller/:action/:id.:format' end

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• iPhone SDK / Objective C Syntax Question

  - by Koppo

  To all, I was looking at the sample project from http://iphoneonrails.com/ and I saw they took the NSObject class and added methods to it for the SOAP calls. Their sample project can be downloaded from here http://iphoneonrails.com/downloads/objective_resource-1.01.zip. My question is related to my lack of knowledge on the following syntax as I haven't seen it yet in a iPhone project. There is a header file called NSObject+ObjectiveResource.h where they declare and change NSObject to have extra methods for this project. Is the "+ObjectiveResource.h" in the name there a special syntax or is that just the naming convention of the developers. Finally inside the class NSObject we have the following #import <Foundation/Foundation.h> @interface NSObject (ObjectiveResource) // Response Formats typedef enum { XmlResponse = 0, JSONResponse, } ORSResponseFormat; // Resource configuration + (NSString *)getRemoteSite; + (void)setRemoteSite:(NSString*)siteURL; + (NSString *)getRemoteUser; + (void)setRemoteUser:(NSString *)user; + (NSString *)getRemotePassword; + (void)setRemotePassword:(NSString *)password; + (SEL)getRemoteParseDataMethod; + (void)setRemoteParseDataMethod:(SEL)parseMethod; + (SEL) getRemoteSerializeMethod; + (void) setRemoteSerializeMethod:(SEL)serializeMethod; + (NSString *)getRemoteProtocolExtension; + (void)setRemoteProtocolExtension:(NSString *)protocolExtension; + (void)setRemoteResponseType:(ORSResponseFormat) format; + (ORSResponseFormat)getRemoteResponseType; // Finders + (NSArray *)findAllRemote; + (NSArray *)findAllRemoteWithResponse:(NSError **)aError; + (id)findRemote:(NSString *)elementId; + (id)findRemote:(NSString *)elementId withResponse:(NSError **)aError; // URL construction accessors + (NSString *)getRemoteElementName; + (NSString *)getRemoteCollectionName; + (NSString *)getRemoteElementPath:(NSString *)elementId; + (NSString *)getRemoteCollectionPath; + (NSString *)getRemoteCollectionPathWithParameters:(NSDictionary *)parameters; + (NSString *)populateRemotePath:(NSString *)path withParameters:(NSDictionary *)parameters; // Instance-specific methods - (id)getRemoteId; - (void)setRemoteId:(id)orsId; - (NSString *)getRemoteClassIdName; - (BOOL)createRemote; - (BOOL)createRemoteWithResponse:(NSError **)aError; - (BOOL)createRemoteWithParameters:(NSDictionary *)parameters; - (BOOL)createRemoteWithParameters:(NSDictionary *)parameters andResponse:(NSError **)aError; - (BOOL)destroyRemote; - (BOOL)destroyRemoteWithResponse:(NSError **)aError; - (BOOL)updateRemote; - (BOOL)updateRemoteWithResponse:(NSError **)aError; - (BOOL)saveRemote; - (BOOL)saveRemoteWithResponse:(NSError **)aError; - (BOOL)createRemoteAtPath:(NSString *)path withResponse:(NSError **)aError; - (BOOL)updateRemoteAtPath:(NSString *)path withResponse:(NSError **)aError; - (BOOL)destroyRemoteAtPath:(NSString *)path withResponse:(NSError **)aError; // Instance helpers for getting at commonly used class-level values - (NSString *)getRemoteCollectionPath; - (NSString *)convertToRemoteExpectedType; //Equality test for remote enabled objects based on class name and remote id - (BOOL)isEqualToRemote:(id)anObject; - (NSUInteger)hashForRemote; @end What is the "ObjectiveResource" in the () mean for NSObject? What is that telling Xcode and the compiler about what is happening..? After that things look normal to me as they have various static and instance methods. I know that by doing this all user classes that inherit from NSObject now have all the extra methods for this project. My question is what is the parenthesis are doing after the NSObject. Is that referencing a header file, or is that letting the compiler know that this class is being over ridden. Thanks again and my apologies ahead of time if this is a dumb question but just trying to learn what I lack.

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• Search engine solution for Django that actually works?

  - by prometheus

  The story so far: Decided to go with Xapian as search backend because it has all search-engine features I was looking for, knows about Unicode, stemming, has few dependencies and requires no bloated app-server installation on top of it. Tried Django and Haystack (plus xapian-haystack, the backend glue code to tie Haystack to Xapian) because it was advertised on quite some blogs as "working". Did not work. Neither django-haystack nor the xapian-haystack project provide a version combination that actually works together. MASTER from both projects yields an error from Xapian, so it's not stable at all. Haystack 1.0.1 and xapian-haystack 1.0.x/1.1.0 are not API-compatible. Plus, in a minimally working installation of Haystack 1.0.1 and xapian-haystack MASTER, any complex query yields zero results due to errors in either django-haystack or xapian-haystack (I double-verified this), maybe because the unit-tests actually test very simple cases, and no edge-cases at all. Tried Djapian. The source-code is riddled with spelling errors (mind you, in variable names, not comments), documentation is also riddled with ambiguities and outdated information that will never lead to a working installation. Not surprisingly, users rarely ask for features but how to get it working in the first place. Next on the plate: exploring Solr (installing a Java environment plus Tomcat gives me headaches, the machine is RAM- and CPU-constrained), or Lucene (slightly less headaches, but still). Before I proceed spending more time with a solution that might or might not work as advertised, I'd like to know: Did anyone ever get an actual, real-world search solution working in Django? I'm serious. I find it really frustrating reading about "large problems mostly solved", and then realizing that you will never get a working installation from the source-code because, actually, all bloggers dealing with those "mostly solved problems" never went past basic installation and copy-pasting the official tutorials. So here are the requirements: must be able to search for 10-100 terms in one query must handle + (term must be present) and - (term must not be present), AND/OR must handle arbitrary grouping (i.e. parentheses around AND/OR) must allow for Django-ORM filtering before or after fulltext-search (i.e. pre-/post-processing of results with the full set of filters that Django knows about) alternatively, there must be a facility to bulk-fetch the result set and transform it into a QuerySet should be light on the machine, so preferably no humongous JVM and Java-based app-server installation Is there anything out there that does this? I'm not interested in anecdotal evidence, or references to some blog posts that claim it should be working. I'd like to hear from someone who actually has a fully-functional setup working in the real world, under real conditions, with real queries. EDIT: Let me repeat again that I'm not so much interested in anecdotal evidence that someone, somewhere has a somewhat running installation working with unspecified properties. I already went there, I read all the blog posts, mailing lists, I contacted the authors, but when it came to actual implementation of real-world scenarios, nothing ever worked as advertised. Also, and a user below brought that point up as well, considering the TCO of any project, I'm definitely not interested in hearing that someone, somewhere was able to pull it off once a vendor parachuted in an unknown number of specialists to monkey-patch the whole installation with specific domain-knowledge that's documented nowhere. So, please, if you claim you have a working installation that actually satisfies minimum requirements for a full-fledged search (see requirements above), please provide the following so that we can all benefit from a search solution for Django that actually solves the problem: exact Linux distribution, release version, exact release version of Haystack (or equivalent) and release version of search backend, exact release version of the search engine publicly (!) available documentation how to set up all components exactly in the way that your installation was set up such that the minimal requirements above are met. Thank you.

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• Search engine solution for Django that actually works?

  - by prometheus

  The story so far: Decided to go with Xapian as search backend because it has all search-engine features I was looking for, knows about Unicode, stemming, has few dependencies and requires no bloated app-server installation on top of it. Tried Django and Haystack (plus xapian-haystack, the backend glue code to tie Haystack to Xapian) because it was advertised on quite some blogs as "working". Did not work. Neither django-haystack nor the xapian-haystack project provide a version combination that actually works together. MASTER from both projects yields an error from Xapian, so it's not stable at all. Haystack 1.0.1 and xapian-haystack 1.0.x/1.1.0 are not API-compatible. Plus, in a minimally working installation of Haystack 1.0.1 and xapian-haystack MASTER, any complex query yields zero results due to errors in either django-haystack or xapian-haystack (I double-verified this), maybe because the unit-tests actually test very simple cases, and no edge-cases at all. Tried Djapian. The source-code is riddled with spelling errors (mind you, in variable names, not comments), documentation is also riddled with ambiguities and outdated information that will never lead to a working installation. Not surprisingly, users rarely ask for features but how to get it working in the first place. Next on the plate: exploring Solr (installing a Java environment plus Tomcat gives me headaches, the machine is RAM- and CPU-constrained), or Lucene (slightly less headaches, but still). Before I proceed spending more time with a solution that might or might not work as advertised, I'd like to know: Did anyone ever get an actual, real-world search solution working in Django? I'm serious. I find it really frustrating reading about "large problems mostly solved", and then realizing that you will never get a working installation from the source-code because, actually, all bloggers dealing with those "mostly solved problems" never went past basic installation and copy-pasting the official tutorials. So here are the requirements: must be able to search for 10-100 terms in one query must handle + (term must be present) and - (term must not be present), AND/OR must handle arbitrary grouping (i.e. parentheses around AND/OR) must allow for Django-ORM filtering before or after fulltext-search (i.e. pre-/post-processing of results with the full set of filters that Django knows about) alternatively, there must be a facility to bulk-fetch the result set and transform it into a QuerySet should be light on the machine, so preferably no humongous JVM and Java-based app-server installation Is there anything out there that does this? I'm not interested in anecdotal evidence, or references to some blog posts that claim it should be working. I'd like to hear from someone who actually has a fully-functional setup working in the real world, under real conditions, with real queries. EDIT: Let me repeat again that I'm not so much interested in anecdotal evidence that someone, somewhere has a somewhat running installation working with unspecified properties. I already went there, I read all the blog posts, mailing lists, I contacted the authors, but when it came to actual implementation of real-world scenarios, nothing ever worked as advertised. Also, and a user below brought that point up as well, considering the TCO of any project, I'm definitely not interested in hearing that someone, somewhere was able to pull it off once a vendor parachuted in an unknown number of specialists to monkey-patch the whole installation with specific domain-knowledge that's documented nowhere. So, please, if you claim you have a working installation that actually satisfies minimum requirements for a full-fledged search (see requirements above), please provide the following so that we can all benefit from a search solution for Django that actually solves the problem: exact Linux distribution, release version, exact release version of Haystack (or equivalent) and release version of search backend, exact release version of the search engine publicly (!) available documentation how to set up all components exactly in the way that your installation was set up such that the minimal requirements above are met. Thank you.

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• Spotlight Infinite Indexing issue (external data drive)

  - by Manca Weeks

  This is an external drive, formerly a boot drive which is now in use only to access music files (sibelius, audio, midi, live, logic etc.) without transferring the data into a new boot system, partly because of the issue I am about to describe, but mostly because the majority of the data is mainly there for archival purposes. The user is a composer and prominent musician and needs to be able to rehash the data at will. I have tried several things - here is a list: - make complete filesystem clone with antonio diaz's ddrescue - run Disk Warrior on copy, repair whatever errors occurred - wipe out all ACLs on entire drive - set all permissions to the same value - wide open 777 - remove any system data (applications, system files, including hidden files to the best of my knowledge) by selecting only non-system/app data and using Carbon Copy Cloner to put only the data of interest onto a newly formatted drive - transfer data to newly formatted drive folder by folder, resetting the spotlight index in between adding each to observe for issues (interesting here is that no issues occurred except for in Documents folder - when I transferred only the Documents folder to a newly formatted drive on its own - no trouble. It appears almost as thought it may not be the content but the quantity or specific combination of data that results in problems) - use DataRescue to transfer the data to yet another newly formatted drive to expose any missed hidden files Between each of the above steps I stopped Spotlight (search for anything beginning with md in Activity Monitor - All Processes and quitting it), deleted the .Spotlight-V100 directory from the affected drive. Restart Splotlight indexing by adding drive to Spotlight privacy list and removing it. In each case the same issue occurs - Spotlight begins indexing normally (or so it seems), then the index estimated time increases, usually to 4 hours remaining. This is where it gets stuck and continues to predict 4 hours remaining but never finishes. Sometimes I can't eject the drive and have to quit the md.. processes from Activity Monitor to be able to eject the drive without Force Eject. Once I disconnect the drive after the 4 hours remaining situation - if I reattach it, Spotlight forever estimates remaining time and never gets going again. So there it is. It is apparently not a filesystem issue, not a permissions issue and not tied to any particular piece of hardware or protocol (used USB and FW drives). I have tried this on several machines (3 to be precise) and in 10.5.8 and 10.6.5. Simply disabling Spotlight on this volume is not an option because the owner has no clue where things are as the data on the volume dates back to music projects and compositions from 2003 and before. He needs to be able to query for results. Anyone got any ideas? ---update 2-6-11 Since I have not received any responses except the one below which appears to misunderstand my point, I am updating this post hoping to get more responses. I have used the terminal command sudo opensnoop -p PID where PID is the mdworker process ID to try and determine what Spotlight is doing and hopefully find the files it's having trouble with. Here's what happens: After indexing for a few hours, mdworker is gone. It no longer shows up in Activity Monitor under "All Processes" and the Terminal window with the opensnoop result stops moving. I then proceeded to execute the same command on mds to see what it was doing and here's what I get, repeatedly: 501 57 mds 21 / 501 57 mds 21 /Volumes/Sno Leppard 501 57 mds 21 /Volumes/Tiger 501 57 mds 21 /Volumes/Leppard 501 57 mds 21 /Volumes/Disk Warrior 501 57 mds 21 /Volumes/ONM Data These represent all the volumes currently mounted in the system. All except ONM Data, which is the one I am trying to index, are excluded from SPotlight indexing at the moment. The sequence above repeats over and over, with slight variation, sometimes skipping one of the volumes. Questions - what happened to mdworker? What is mds doing? I will let this run until tomorrow morning and throughout the day and monitor for any changes. Any input would be very much appreciated. Even if you're not sure what the ultimate answer is, please alert me to anything you think I may be missing. Hopefully at some point we will figure this out... Thanks, M __final edit__ I finally resolved the issue and here is how I did it. I used the terminal command "sudo opensnoop -p PID" where the PID is the process id of the processes I was monitoring. I was looking at all instances of mds and mdworker running in the system. After the third time through indexing the same data set (see info above), I contacted Apple and got to their highest level of support - they were flabbergasted as well. They advised me to install yet another default 10.6.6 system and try again. The same pattern repeated - mds and mdworker(s) would start indexing and eventually the spotlight icon would say 6 hours remaining and all mdworkers were gone, mds at 90% or so of CPU. But I did finally figure out that the first time mdworker stopped like that, the last file it touched was always in the same folder. I excluded that folder from spotlight search and the rest of the data set indexed within about 2 hours with no strange behavior or failures. I copied that folder to another machine and Spotlight barfed immediately. Exclude that folder and all is well again. I have no clue what is causing this behavior, still, but I did find a functional solution to the problem. Anyone with a similar problem - run opensnoop on all instances of mds and mdworker and wait patiently for wdworker to exit. Look at the last file it touched and exclude the enclosing folder from being indexed. I was able to repeat the issue and solution on 2 different installs and 2 different copies of the data set. Hope this helps. If we find an actual cause of the folder being such a problem (it is called MICHAEL BRECKER RECORD SOLOS and contains almost 1 GB of audio related files - performer, live, SD2 - things like that), I will edit again to let you all know. Thanks for ay attempts to help, M

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• What is Causing this IIS 7 Web Service Sporadic Connectivity Error?

  - by dpalau

  On sporadic occasions we receive the following error when attempting to call an .asmx web service from a .Net client application: "The underlying connection was closed: A connection that was expected to be kept alive was closed by the server. Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host." By sporadic I mean that it might occur zero, once every few days, or a half-dozen times a day for some users. It will never occur for the first web service call of a user. And the subsequent (usually the same) call will always work immediately after the failure. The failures happen across a variety of methods in the service and usually happens between 15-20 seconds (according to the log) from the time of the request. Looking in the IIS site log for the particular call will show one or the other of the following windows error codes: 121: The semaphore timeout period has elapsed. 1236: The network connection was aborted by the local system. Some additional environment details: Running on internal network web farm consisting of two servers running IIS7 on Windows Server 2008 OS. These problems did not occur when running in an older IIS6 web farm of three servers running on Windows Server 2003 (and we use a single IIS6/2003 instance for our development and staging environments with no issues). EDIT: Also, all of these server instances are VMWare virtual machines, not sure if that is a surprise anymore or not. The web service is a .Net 2.0/3.5 compiled .asmx web service that has its own application pool (.Net 2.0, integrated pipeline). Only has Windows Authentication enabled. We have another web service on the farm that uses the same physical path as the primary service, the only difference being that Basic Authentication is enabled. This is used for a portion of our ERP system. Have tried using the same and different application pool - no effect on the error. This site isn't hit as often as the primary site and has never had an error. As mentioned, the error will only happen when called from the .Net client - not from other applications. The client application is always creating a new web service object for each request and setting the service credentials to System.Net.CredentialCache.DefaultCredentials. The application is either deployed locally to a client or run in a Citrix server session. Those users running in Citrix doesn't seem to experience the issue, only locally deployed clients. The Citrix servers and the web farm are located in the same physical location and are located in the same IP range (10.67.xx.xx). Locally deployed clients experiencing the error are located elsewhere (10.105.xx.xx, 10.31.xx.xx). I've checked the OS logs to see if I can see any problems but nothing really sticks out. EDIT: Actually, I myself just ran into the error a little bit ago. I decided to check out the logs again and saw that there was a Security log entry of "Audit Failure" at the 'same' time (IIS log entry at 1:39:59, event log entry at 1:39:50). Not sure if this is a coincidence or not, I'll have to check out the logs of previous errors. I'm probably grasping for straws but the details: Log Name: Security Source: Microsoft-Windows-Security-Auditing Date: 7/8/2009 1:39:50 PM Event ID: 5159 Task Category: Filtering Platform Connection Level: Information Keywords: Audit Failure User: N/A Computer: is071019.<**.net Description: The Windows Filtering Platform has blocked a bind to a local port. Application Information: Process ID: 1260 Application Name: \device\harddiskvolume1\windows\system32\svchost.exe Network Information: Source Address: 0.0.0.0 Source Port: 54802 Protocol: 17 Filter Information: Filter Run-Time ID: 0 Layer Name: Resource Assignment Layer Run-Time ID: 36 I've also tried to use Failed Request Tracing in IIS7 but the service call never actually gets to where FRT can capture it (even though the failure is logged in the web service log). The network infrastructure group said they checked out the DNS and any NIC settings are correct so there is no 'flapping'. Everything pans out. I'm not sure that they checked out any domain controller servers though to see if that could be an issue. Any ideas? Or any other debugging strategies to get to the bottom of this? I'm just the developer in charge of the software and don't really have the knowledge on what to investigate from the networking side of things - although it does sound like a networking issue to me based on what is happening. Thanks in advance for any help.

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