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  • A Knights Tale

    - by Phil Factor
    There are so many lessons to be learned from the story of Knight Capital losing nearly half a billion dollars as a result of a deployment gone wrong. The Knight Capital Group (KCG N) was an American global financial services firm engaging in market making, electronic execution, and institutional sales and trading. According to the recent order (File No.3.15570) against Knight Capital by U.S. Securities and Exchange Commission?, Knight had, for many years used some software which broke up incoming “parent” orders into smaller “child” orders that were then transmitted to various exchanges or trading venues for execution. A tracking ‘cumulative quantity’ function counted the number of ‘child’ orders and stopped the process once the total of child orders matched the ‘parent’ and so the parent order had been completed. Back in the mists of time, some code had been added to it  which was excuted if a particular flag was set. It was called ‘power peg’ and seems to have had a similar design and purpose, but, one guesses, would have shared the same tracking function. This code had been abandoned in 2003, but never deleted. In 2005, The tracking function was moved to an earlier point in the main process. It would seem from the account that, from that point, had that flag ever been set, the old ‘Power Peg’ would have been executed like Godzilla bursting from the ice, making child orders without limit without any tracking function. It wasn’t, presumably because the software that set the flag was removed. In 2012, nearly a decade after ‘Power Peg’ was abandoned, Knight prepared a new module to their software to cope with the imminent Retail Liquidity Program (RLP) for the New York Stock Exchange. By this time, the flag had remained unused and someone made the fateful decision to reuse it, and replace the old ‘power peg’ code with this new RLP code. Had the two actions been done together in a single automated deployment, and the new deployment tested, all would have been well. It wasn’t. To quote… “Beginning on July 27, 2012, Knight deployed the new RLP code in SMARS in stages by placing it on a limited number of servers in SMARS on successive days. During the deployment of the new code, however, one of Knight’s technicians did not copy the new code to one of the eight SMARS computer servers. Knight did not have a second technician review this deployment and no one at Knight realized that the Power Peg code had not been removed from the eighth server, nor the new RLP code added. Knight had no written procedures that required such a review.” (para 15) “On August 1, Knight received orders from broker-dealers whose customers were eligible to participate in the RLP. The seven servers that received the new code processed these orders correctly. However, orders sent with the repurposed flag to the eighth server triggered the defective Power Peg code still present on that server. As a result, this server began sending child orders to certain trading centers for execution. Because the cumulative quantity function had been moved, this server continuously sent child orders, in rapid sequence, for each incoming parent order without regard to the number of share executions Knight had already received from trading centers. Although one part of Knight’s order handling system recognized that the parent orders had been filled, this information was not communicated to SMARS.” (para 16) SMARS routed millions of orders into the market over a 45-minute period, and obtained over 4 million executions in 154 stocks for more than 397 million shares. By the time that Knight stopped sending the orders, Knight had assumed a net long position in 80 stocks of approximately $3.5 billion and a net short position in 74 stocks of approximately $3.15 billion. Knight’s shares dropped more than 20% after traders saw extreme volume spikes in a number of stocks, including preferred shares of Wells Fargo (JWF) and semiconductor company Spansion (CODE). Both stocks, which see roughly 100,000 trade per day, had changed hands more than 4 million times by late morning. Ultimately, Knight lost over $460 million from this wild 45 minutes of trading. Obviously, I’m interested in all this because, at one time, I used to write trading systems for the City of London. Obviously, the US SEC is in a far better position than any of us to work out the failings of Knight’s IT department, and the report makes for painful reading. I can’t help observing, though, that even with the breathtaking mistakes all along the way, that a robust automated deployment process that was ‘all-or-nothing’, and tested from soup to nuts would have prevented the disaster. The report reads like a Greek Tragedy. All the way along one wants to shout ‘No! not that way!’ and ‘Aargh! Don’t do it!’. As the tragedy unfolds, the audience weeps for the players, trapped by a cruel fate. All application development and deployment requires defense in depth. All IT goes wrong occasionally, but if there is a culture of defensive programming throughout, the consequences are usually containable. For financial systems, these defenses are required by statute, and ignored only by the foolish. Knight’s mistakes weren’t made by just one hapless sysadmin, but were progressive errors by an  IT culture spanning at least ten years.  One can spell these out, but I think they’re obvious. One can only hope that the industry studies what happened in detail, learns from the mistakes, and draws the right conclusions.

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  • What would most games benefit from having?

    - by Phil
    I think I've seen "questions" like this on stackoverflow but sorry if I'm overstepping any bounds. Inspired by my recent question and all the nice answers (Checklist for finished game?) I think every gamedev out there has something he/she thinks that almost every game should have. That knowledge is welcome here! So this is probably going to be an inspirational subjective list of some sorts and the point is that anyone reading this question will see a point or two that they've overlooked in their own development and might benefit from adding. I think a good example might be: "some sort of manual or help section. Of course it should be proportional to how advanced the game is. Some users won't need it and won't go looking for it but the other ones that do will become very frustrated if they can't remember how to do something specific that should be in the manual". A bad example might be "good gameplay". Of course every game benefits from this but the answer is not very helpful.

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  • Software Tuned to Humanity

    - by Phil Factor
    I learned a great deal from a cynical old programmer who once told me that the ideal length of time for a compiler to do its work was the same time it took to roll a cigarette. For development work, this is oh so true. After intently looking at the editing window for an hour or so, it was a relief to look up, stretch, focus the eyes on something else, and roll the possibly-metaphorical cigarette. This was software tuned to humanity. Likewise, a user’s perception of the “ideal” time that an application will take to move from frame to frame, to retrieve information, or to process their input has remained remarkably static for about thirty years, at around 200 ms. Anything else appears, and always has, to be either fast or slow. This could explain why commercial applications, unlike games, simulations and communications, aren’t noticeably faster now than they were when I started programming in the Seventies. Sure, they do a great deal more, but the SLAs that I negotiated in the 1980s for application performance are very similar to what they are nowadays. To prove to myself that this wasn’t just some rose-tinted misperception on my part, I cranked up a Z80-based Jonos CP/M machine (1985) in the roof-space. Within 20 seconds from cold, it had loaded Wordstar and I was ready to write. OK, I got it wrong: some things were faster 30 years ago. Sure, I’d now have had all sorts of animations, wizzy graphics, and other comforting features, but it seems a pity that we have used all that extra CPU and memory to increase the scope of what we develop, and the graphical prettiness, but not to speed the processes needed to complete a business procedure. Never mind the weight, the response time’s great! To achieve 200 ms response times on a Z80, or similar, performance considerations influenced everything one did as a developer. If it meant writing an entire application in assembly code, applying every smart algorithm, and shortcut imaginable to get the application to perform to spec, then so be it. As a result, I’m a dyed-in-the-wool performance freak and find it difficult to change my habits. Conversely, many developers now seem to feel quite differently. While all will acknowledge that performance is important, it’s no longer the virtue is once was, and other factors such as user-experience now take precedence. Am I wrong? If not, then perhaps we need a new school of development technique to rival Agile, dedicated once again to producing applications that smoke the rear wheels rather than pootle elegantly to the shops; that forgo skeuomorphism, cute animation, or architectural elegance in favor of the smell of hot rubber. I struggle to name an application I use that is truly notable for its blistering performance, and would dearly love one to do my everyday work – just as long as it doesn’t go faster than my brain.

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  • Alternatives for saving data with jquery

    - by Phil Vallone
    I am not sure if this question is considered too broad, but I would like to reach out to my fellow programmers to see what alternatives are out there for saving data using jquery. I have a content management system that generates an set of HTML pages called an IETM (Interactive Electronic Technical Manual). The HTML pages are written in HTML and uses jquery. The ITEM is meant to be light weight, portable and run on most modern browsers. I am looking for a way to save data. I have considered cookies and sqlite. Are there any other alternatives for saving data using jquery?

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  • Hadoop, NOSQL, and the Relational Model

    - by Phil Factor
    (Guest Editorial for the IT Pro/SysAdmin Newsletter)Whereas Relational Databases fit the world of commerce like a glove, it is useless to pretend that they are a perfect fit for all human endeavours. Although, with SQL Server, we’ve made great strides with indexing text, in processing spatial data and processing markup, there is still a problem in dealing efficiently with large volumes of ephemeral semi-structured data. Key-value stores such as Cassandra, Project Voldemort, and Riak are of great value for ephemeral data, and seem of equal value as a data-feed that provides aggregations to an RDBMS. However, the Document databases such as MongoDB and CouchDB are ideal for semi-structured data for which no fixed schema exists; analytics and logging are obvious examples. NoSQL products, such as MongoDB, tackle the semi-structured data problem with panache. MongoDB is designed with a simple document-oriented data model that scales horizontally across multiple servers. It doesn’t impose a schema, and relies on the application to enforce the data structure. This is another take on the old ‘EAV’ problem (where you don’t know in advance all the attributes of a particular entity) It uses a clever replica set design that allows automatic failover, and uses journaling for data durability. It allows indexing and ad-hoc querying. However, for SQL Server users, the obvious choice for handling semi-structured data is Apache Hadoop. There will soon be an ODBC Driver for Apache Hive .and an Add-in for Excel. Additionally, there are now two Hadoop-based connectors for SQL Server; the Apache Hadoop connector for SQL Server 2008 R2, and the SQL Server Parallel Data Warehouse (PDW) connector. We can connect to Hadoop process the semi-structured data and then store it in SQL Server. For one steeped in the culture of Relational SQL Databases, I might be expected to throw up my hands in the air in a gesture of contempt for a technology that was, judging by the overblown journalism on the subject, about to make my own profession as archaic as the Saggar makers bottom knocker (a potter’s assistant who helped the saggar maker to make the bottom of the saggar by placing clay in a metal hoop and bashing it). However, on the contrary, I find that I'm delighted with the advances made by the NoSQL databases in the past few years. Having the flow of ideas from the NoSQL providers will knock any trace of complacency out of the providers of Relational Databases and inspire them into back-fitting some features, such as horizontal scaling, with sharding and automatic failover into SQL-based RDBMSs. It will do the breed a power of good to benefit from all this lateral thinking.

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  • At times, you need to hire a professional.

    - by Phil Factor
    After months of increasingly demanding toil, the development team I belonged to was told that the project was to be canned and the whole team would be fired.  I’d been brought into the team as an expert in the data implications of a business re-engineering of a major financial institution. Nowadays, you’d call me a data architect, I suppose.  I’d spent a happy year being paid consultancy fees solving a succession of interesting problems until the point when the company lost is nerve, and closed the entire initiative. The IT industry was in one of its characteristic mood-swings downwards.  After the announcement, we met in the canteen. A few developers had scented the smell of death around the project already hand had been applying unsuccessfully for jobs. There was a sense of doom in the mass of dishevelled and bleary-eyed developers. After giving vent to anger and despair, talk turned to getting new employment. It was then that I perked up. I’m not an obvious choice to give advice on getting, or passing,  IT interviews. I reckon I’ve failed most of the job interviews I’ve ever attended. I once even failed an interview for a job I’d already been doing perfectly well for a year. The jobs I’ve got have mostly been from personal recommendation. Paradoxically though, from years as a manager trying to recruit good staff, I know a lot about what IT managers are looking for.  I gave an impassioned speech outlining the important factors in getting to an interview.  The most important thing, certainly in my time at work is the quality of the résumé or CV. I can’t even guess the huge number of CVs (résumés) I’ve read through, scanning for candidates worth interviewing.  Many IT Developers find it impossible to describe their  career succinctly on two sides of paper.  They leave chunks of their life out (were they in prison?), get immersed in detail, put in irrelevancies, describe what was going on at work rather than what they themselves did, exaggerate their importance, criticize their previous employers, aren’t  aware of the important aspects of a role to a potential employer, suffer from shyness and modesty,  and lack any sort of organized perspective of their work. There are many ways of failing to write a decent CV. Many developers suffer from the delusion that their worth can be recognized purely from the code that they write, and shy away from anything that seems like self-aggrandizement. No.  A resume must make a good impression, which means presenting the facts about yourself in a clear and positive way. You can’t do it yourself. Why not have your resume professionally written? A good professional CV Writer will know the qualities being looked for in a CV and interrogate you to winkle them out. Their job is to make order and sense out of a confused career, to summarize in one page a mass of detail that presents to any recruiter the information that’s wanted. To stand back and describe an accurate summary of your skills, and work-experiences dispassionately, without rancor, pity or modesty. You are no more capable of producing an objective documentation of your career than you are of taking your own appendix out.  My next recommendation was more controversial. This is to have a professional image overhaul, or makeover, followed by a professionally-taken photo portrait. I discovered this by accident. It is normal for IT professionals to face impossible deadlines and long working hours by looking more and more like something that had recently blocked a sink. Whilst working in IT, and in a state of personal dishevelment, I’d been offered the role in a high-powered amateur production of an old ex- Broadway show, purely for my singing voice. I was supposed to be the presentable star. When the production team saw me, the air was thick with tension and despair. I was dragged kicking and protesting through a succession of desperate grooming, scrubbing, dressing, dieting. I emerged feeling like “That jewelled mass of millinery, That oiled and curled Assyrian bull, Smelling of musk and of insolence.” (Tennyson Maud; A Monodrama (1855) Section v1 stanza 6) I was then photographed by a professional stage photographer.  When the photographs were delivered, I was amazed. It wasn’t me, but it looked somehow respectable, confident, trustworthy.   A while later, when the show had ended, I took the photos, and used them for work. They went with the CV to job applications. It did the trick better than I could ever imagine.  My views went down big with the developers. Old rivalries were put immediately to one side. We voted, with a show of hands, to devote our energies for the entire notice period to getting employable. We had a team sourcing the CV Writer,  a team organising the make-overs and photographer, and a third team arranging  mock interviews. A fourth team determined the best websites and agencies for recruitment, with the help of friends in the trade.  Because there were around thirty developers, we were in a good negotiating position.  Of the three CV Writers we found who lived locally, one proved exceptional. She was an ex-journalist with an eye to detail, and years of experience in manipulating language. We tried her skills out on a developer who seemed a hopeless case, and he was called to interview within a week.  I was surprised, too, how many companies were experts at image makeovers. Within the month, we all looked like those weird slick  people in the ‘Office-tagged’ stock photographs who stare keenly and interestedly at PowerPoint slides in sleek chromium-plated high-rise offices. The portraits we used still adorn the entries of many of my ex-colleagues in LinkedIn. After a months’ worth of mock interviews, and technical Q&A, our stutters, hesitations, evasions and periphrastic circumlocutions were all gone.  There is little more to relate. With the résumés or CVs, mugshots, and schooling in how to pass interviews, we’d all got new and better-paid jobs well  before our month’s notice was ended. Whilst normally, an IT team under the axe is a sad and depressed place to belong to, this wonderful group of people had proved the power of organized group action in turning the experience to advantage. It left us feeling slightly guilty that we were somehow cheating, but I guess we were merely leveling the playing-field.

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  • Database Migration Scripts: Getting from place A to place B

    - by Phil Factor
    We’ll be looking at a typical database ‘migration’ script which uses an unusual technique to migrate existing ‘de-normalised’ data into a more correct form. So, the book-distribution business that uses the PUBS database has gradually grown organically, and has slipped into ‘de-normalisation’ habits. What’s this? A new column with a list of tags or ‘types’ assigned to books. Because books aren’t really in just one category, someone has ‘cured’ the mismatch between the database and the business requirements. This is fine, but it is now proving difficult for their new website that allows searches by tags. Any request for history book really has to look in the entire list of associated tags rather than the ‘Type’ field that only keeps the primary tag. We have other problems. The TypleList column has duplicates in there which will be affecting the reporting, and there is the danger of mis-spellings getting there. The reporting system can’t be persuaded to do reports based on the tags and the Database developers are complaining about the unCoddly things going on in their database. In your version of PUBS, this extra column doesn’t exist, so we’ve added it and put in 10,000 titles using SQL Data Generator. /* So how do we refactor this database? firstly, we create a table of all the tags. */IF  OBJECT_ID('TagName') IS NULL OR OBJECT_ID('TagTitle') IS NULL  BEGIN  CREATE TABLE  TagName (TagName_ID INT IDENTITY(1,1) PRIMARY KEY ,     Tag VARCHAR(20) NOT NULL UNIQUE)  /* ...and we insert into it all the tags from the list (remembering to take out any leading spaces */  INSERT INTO TagName (Tag)     SELECT DISTINCT LTRIM(x.y.value('.', 'Varchar(80)')) AS [Tag]     FROM     (SELECT  Title_ID,          CONVERT(XML, '<list><i>' + REPLACE(TypeList, ',', '</i><i>') + '</i></list>')          AS XMLkeywords          FROM   dbo.titles)g    CROSS APPLY XMLkeywords.nodes('/list/i/text()') AS x ( y )  /* we can then use this table to provide a table that relates tags to articles */  CREATE TABLE TagTitle   (TagTitle_ID INT IDENTITY(1, 1),   [title_id] [dbo].[tid] NOT NULL REFERENCES titles (Title_ID),   TagName_ID INT NOT NULL REFERENCES TagName (Tagname_ID)   CONSTRAINT [PK_TagTitle]       PRIMARY KEY CLUSTERED ([title_id] ASC, TagName_ID)       ON [PRIMARY])        CREATE NONCLUSTERED INDEX idxTagName_ID  ON  TagTitle (TagName_ID)  INCLUDE (TagTitle_ID,title_id)        /* ...and it is easy to fill this with the tags for each title ... */        INSERT INTO TagTitle (Title_ID, TagName_ID)    SELECT DISTINCT Title_ID, TagName_ID      FROM        (SELECT  Title_ID,          CONVERT(XML, '<list><i>' + REPLACE(TypeList, ',', '</i><i>') + '</i></list>')          AS XMLkeywords          FROM   dbo.titles)g    CROSS APPLY XMLkeywords.nodes('/list/i/text()') AS x ( y )    INNER JOIN TagName ON TagName.Tag=LTRIM(x.y.value('.', 'Varchar(80)'))    END    /* That's all there was to it. Now we can select all titles that have the military tag, just to try things out */SELECT Title FROM titles  INNER JOIN TagTitle ON titles.title_ID=TagTitle.Title_ID  INNER JOIN Tagname ON Tagname.TagName_ID=TagTitle.TagName_ID  WHERE tagname.tag='Military'/* and see the top ten most popular tags for titles */SELECT Tag, COUNT(*) FROM titles  INNER JOIN TagTitle ON titles.title_ID=TagTitle.Title_ID  INNER JOIN Tagname ON Tagname.TagName_ID=TagTitle.TagName_ID  GROUP BY Tag ORDER BY COUNT(*) DESC/* and if you still want your list of tags for each title, then here they are */SELECT title_ID, title, STUFF(  (SELECT ','+tagname.tag FROM titles thisTitle    INNER JOIN TagTitle ON titles.title_ID=TagTitle.Title_ID    INNER JOIN Tagname ON Tagname.TagName_ID=TagTitle.TagName_ID  WHERE ThisTitle.title_id=titles.title_ID  FOR XML PATH(''), TYPE).value('.', 'varchar(max)')  ,1,1,'')    FROM titles  ORDER BY title_ID So we’ve refactored our PUBS database without pain. We’ve even put in a check to prevent it being re-run once the new tables are created. Here is the diagram of the new tag relationship We’ve done both the DDL to create the tables and their associated components, and the DML to put the data in them. I could have also included the script to remove the de-normalised TypeList column, but I’d do a whole lot of tests first before doing that. Yes, I’ve left out the assertion tests too, which should check the edge cases and make sure the result is what you’d expect. One thing I can’t quite figure out is how to deal with an ordered list using this simple XML-based technique. We can ensure that, if we have to produce a list of tags, we can get the primary ‘type’ to be first in the list, but what if the entire order is significant? Thank goodness it isn’t in this case. If it were, we might have to revisit a string-splitter function that returns the ordinal position of each component in the sequence. You’ll see immediately that we can create a synchronisation script for deployment from a comparison tool such as SQL Compare, to change the schema (DDL). On the other hand, no tool could do the DML to stuff the data into the new table, since there is no way that any tool will be able to work out where the data should go. We used some pretty hairy code to deal with a slightly untypical problem. We would have to do this migration by hand, and it has to go into source control as a batch. If most of your database changes are to be deployed by an automated process, then there must be a way of over-riding this part of the data synchronisation process to do this part of the process taking the part of the script that fills the tables, Checking that the tables have not already been filled, and executing it as part of the transaction. Of course, you might prefer the approach I’ve taken with the script of creating the tables in the same batch as the data conversion process, and then using the presence of the tables to prevent the script from being re-run. The problem with scripting a refactoring change to a database is that it has to work both ways. If we install the new system and then have to rollback the changes, several books may have been added, or had their tags changed, in the meantime. Yes, you have to script any rollback! These have to be mercilessly tested, and put in source control just in case of the rollback of a deployment after it has been in place for any length of time. I’ve shown you how to do this with the part of the script .. /* and if you still want your list of tags for each title, then here they are */SELECT title_ID, title, STUFF(  (SELECT ','+tagname.tag FROM titles thisTitle    INNER JOIN TagTitle ON titles.title_ID=TagTitle.Title_ID    INNER JOIN Tagname ON Tagname.TagName_ID=TagTitle.TagName_ID  WHERE ThisTitle.title_id=titles.title_ID  FOR XML PATH(''), TYPE).value('.', 'varchar(max)')  ,1,1,'')    FROM titles  ORDER BY title_ID …which would be turned into an UPDATE … FROM script. UPDATE titles SET  typelist= ThisTaglistFROM     (SELECT title_ID, title, STUFF(    (SELECT ','+tagname.tag FROM titles thisTitle      INNER JOIN TagTitle ON titles.title_ID=TagTitle.Title_ID      INNER JOIN Tagname ON Tagname.TagName_ID=TagTitle.TagName_ID    WHERE ThisTitle.title_id=titles.title_ID    ORDER BY CASE WHEN tagname.tag=titles.[type] THEN 1 ELSE 0  END DESC    FOR XML PATH(''), TYPE).value('.', 'varchar(max)')    ,1,1,'')  AS ThisTagList  FROM titles)fINNER JOIN Titles ON f.title_ID=Titles.title_ID You’ll notice that it isn’t quite a round trip because the tags are in a different order, though we’ve managed to make sure that the primary tag is the first one as originally. So, we’ve improved the database for the poor book distributors using PUBS. It is not a major deal but you’ve got to be prepared to provide a migration script that will go both forwards and backwards. Ideally, database refactoring scripts should be able to go from any version to any other. Schema synchronization scripts can do this pretty easily, but no data synchronisation scripts can deal with serious refactoring jobs without the developers being able to specify how to deal with cases like this.

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  • Pros and cons of creating a print friendly page to remove the use of pdfs?

    - by Phil
    the company I work for has a one page invoice that uses the library tcpdf. they wanted to do some design changes that I found are just incredibly difficult for setting up in .pdf format. Using html/css I could easily create the page and have it print very nicely, but I have a feeling that I am over looking something. What are the pros and cons of setting up a page just for printing? What are the pros and cons of putting out a .pdf? I could also use the CSS inline so that if they wanted to download it and open it they could.

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  • Calc direction vector based on destination vector and distance from enemy in AS3

    - by Phil
    I'm working on a zombie game in AS3 where I want a character to be able to move away from a zombie depending upon how close the zombie is. The character also has a destination that it's trying to get too on the screen. Ok so I have 2 vectors, one pointing to my destination, and one pointing to the zombie which I then invert to get my "away" vector. I then turn the distance between my character and the zombie into a value between 0 and 1. And then I'm stuck on how to get a resultant vector for my character. How would I use my 0-1 value to calculate how much of the away vector is used and how much of the original destination vector is still left if that makes sense? to end up with 1 direction vector to move my character? So if the zombie is right where my character is, then my direction vector = away vector, and if I'm far away from the zombie than my direction vector = destination vector, but how do I calculate the in-between? Ideally need the answer in AS3.

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  • Python Web Applications: What is the way and the method to handle Registrations, Login-Logouts and Cookies? [on hold]

    - by Phil
    I am working on a simple Python web application for learning purposes. I have chosen a very minimalistic and simple framework. I have done a significant amount of research but I couldn't find a source clearly explaining what I need, which is as follows: I would like to learn more about: User registration User Log-ins User Log-outs User auto-logins I have successfully handled items 1 and 3 due to their simple nature. However, I am confused with item 2 (log-ins) and item 4 (auto-logins). When a user enters username and password, and after hashing with salts and matching it in the DB; What information should I store in the cookies in order to keep the user logged in during the session? Do I keep username+password but encrypt them? Both or just password? Do I keep username and a generated key matching their password? If I want the user to be able to auto-login (when they leave and come back to the web page), what information then is kept in the cookies? I don't want to use modules or libraries that handle these things automatically. I want to learn basics and why something is the way it is. I would also like to point out that I do not mind reading anything you might offer on the topic that explains hows and whys. Possibly with algorithm diagrams to show the process. Some information: I know about setting headers, cookies, encryption (up to some level, obviously not an expert!), request objects, SQLAlchemy etc. I don't want any data kept in a single web application server's store. I want multiple app-servers to be handle a user, and whatever needs to be kept on the server to be done with a Postgres/MySQL via SQLAlchemy (I think, this is called stateless?) Thank you.

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  • Documentation and Test Assertions in Databases

    - by Phil Factor
    When I first worked with Sybase/SQL Server, we thought our databases were impressively large but they were, by today’s standards, pathetically small. We had one script to build the whole database. Every script I ever read was richly annotated; it was more like reading a document. Every table had a comment block, and every line would be commented too. At the end of each routine (e.g. procedure) was a quick integration test, or series of test assertions, to check that nothing in the build was broken. We simply ran the build script, stored in the Version Control System, and it pulled everything together in a logical sequence that not only created the database objects but pulled in the static data. This worked fine at the scale we had. The advantage was that one could, by reading the source code, reach a rapid understanding of how the database worked and how one could interface with it. The problem was that it was a system that meant that only one developer at the time could work on the database. It was very easy for a developer to execute accidentally the entire build script rather than the selected section on which he or she was working, thereby cleansing the database of everyone else’s work-in-progress and data. It soon became the fashion to work at the object level, so that programmers could check out individual views, tables, functions, constraints and rules and work on them independently. It was then that I noticed the trend to generate the source for the VCS retrospectively from the development server. Tables were worst affected. You can, of course, add or delete a table’s columns and constraints retrospectively, which means that the existing source no longer represents the current object. If, after your development work, you generate the source from the live table, then you get no block or line comments, and the source script is sprinkled with silly square-brackets and other confetti, thereby rendering it visually indigestible. Routines, too, were affected. In our system, every routine had a directly attached string of unit-tests. A retro-generated routine has no unit-tests or test assertions. Yes, one can still commit our test code to the VCS but it’s a separate module and teams end up running the whole suite of tests for every individual change, rather than just the tests for that routine, which doesn’t scale for database testing. With Extended properties, one can get the best of both worlds, and even use them to put blame, praise or annotations into your VCS. It requires a lot of work, though, particularly the script to generate the table. The problem is that there are no conventional names beyond ‘MS_Description’ for the special use of extended properties. This makes it difficult to do splendid things such ensuring the integrity of the build by running a suite of tests that are actually stored in extended properties within the database and therefore the VCS. We have lost the readability of database source code over the years, and largely jettisoned the use of test assertions as part of the database build. This is not unexpected in view of the increasing complexity of the structure of databases and number of programmers working on them. There must, surely, be a way of getting them back, but I sometimes wonder if I’m one of very few who miss them.

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  • Separating text strings into a table of individual words in SQL via XML.

    - by Phil Factor
    p.MsoNormal {margin-top:0cm; margin-right:0cm; margin-bottom:10.0pt; margin-left:0cm; line-height:115%; font-size:11.0pt; font-family:"Calibri","sans-serif"; } Nearly nine years ago, Mike Rorke of the SQL Server 2005 XML team blogged ‘Querying Over Constructed XML Using Sub-queries’. I remember reading it at the time without being able to think of a use for what he was demonstrating. Just a few weeks ago, whilst preparing my article on searching strings, I got out my trusty function for splitting strings into words and something reminded me of the old blog. I’d been trying to think of a way of using XML to split strings reliably into words. The routine I devised turned out to be slightly slower than the iterative word chop I’ve always used in the past, so I didn’t publish it. It was then I suddenly remembered the old routine. Here is my version of it. I’ve unwrapped it from its obvious home in a function or procedure just so it is easy to appreciate. What it does is to chop a text string into individual words using XQuery and the good old nodes() method. I’ve benchmarked it and it is quicker than any of the SQL ways of doing it that I know about. Obviously, you can’t use the trick I described here to do it, because it is awkward to use REPLACE() on 1…n characters of whitespace. I’ll carry on using my iterative function since it is able to tell me the location of each word as a character-offset from the start, and also because this method leaves punctuation in (removing it takes time!). However, I can see other uses for this in passing lists as input or output parameters, or as return values.   if exists (Select * from sys.xml_schema_collections where name like 'WordList')   drop XML SCHEMA COLLECTION WordList go create xml schema collection WordList as ' <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:element name="words">        <xs:simpleType>               <xs:list itemType="xs:string" />        </xs:simpleType> </xs:element> </xs:schema>'   go   DECLARE @string VARCHAR(MAX) –we'll get some sample data from the great Ogden Nash Select @String='This is a song to celebrate banks, Because they are full of money and you go into them and all you hear is clinks and clanks, Or maybe a sound like the wind in the trees on the hills, Which is the rustling of the thousand dollar bills. Most bankers dwell in marble halls, Which they get to dwell in because they encourage deposits and discourage withdrawals, And particularly because they all observe one rule which woe betides the banker who fails to heed it, Which is you must never lend any money to anybody unless they don''t need it. I know you, you cautious conservative banks! If people are worried about their rent it is your duty to deny them the loan of one nickel, yes, even one copper engraving of the martyred son of the late Nancy Hanks; Yes, if they request fifty dollars to pay for a baby you must look at them like Tarzan looking at an uppity ape in the jungle, And tell them what do they think a bank is, anyhow, they had better go get the money from their wife''s aunt or ungle. But suppose people come in and they have a million and they want another million to pile on top of it, Why, you brim with the milk of human kindness and you urge them to accept every drop of it, And you lend them the million so then they have two million and this gives them the idea that they would be better off with four, So they already have two million as security so you have no hesitation in lending them two more, And all the vice-presidents nod their heads in rhythm, And the only question asked is do the borrowers want the money sent or do they want to take it withm. Because I think they deserve our appreciation and thanks, the jackasses who go around saying that health and happi- ness are everything and money isn''t essential, Because as soon as they have to borrow some unimportant money to maintain their health and happiness they starve to death so they can''t go around any more sneering at good old money, which is nothing short of providential. '   –we now turn it into XML declare @xml_data xml(WordList)  set @xml_data='<words>'+ replace(@string,'&', '&amp;')+'</words>'    select T.ref.value('.', 'nvarchar(100)')  from (Select @xml_data.query('                      for $i in data(/words) return                      element li { $i }               '))  A(list) cross apply A.List.nodes('/li') T(ref)     …which gives (truncated, of course)…

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  • Bluescreen after Ubuntu 12.10 installation, after recommended boot repair "no filesystem found" please help!

    - by Phil
    After I tried to install Ubuntu 12.10 into my Windows 7 a black screen came up and nothing happened for over five minutes. So I force shutdown my computer and started again on the linux CD. I partitioned the Linux partitions manually and installed Ubuntu. At the next reboot I got a bluescreen from Windows three secounds after loading. I tried to repair the problem by using boot-repair. Then I got out the url: http://paste.ubuntu.com/1430803 And after the next restart he told me that he didn't found the filesystem. Because he didn't found the filesystem it was unable to repair it with the windows CD. Then I tried to repair it with TestDisk and was able to change the Windows Partition into NTFS, but I was not able to repair the windows 7 boot partition. Now I get the message that No Bootloader is found when I restart. Please help me.

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  • When things go awry

    - by Phil Factor
    The moment the Entrepreneur opened his mouth on prime-time national TV, spelled out the URL and waxed big on how exciting ‘his’ new website was, I knew I was in for a busy night. I’d designed and built it. All at once, half a million people tried to log into the website. Although all my stress-testing paid off, I have to admit that the network locked up tight long before there was any danger of a database or website problem. Soon afterwards, the Entrepreneur and the Big Boss were there in the autopsy meeting. We picked through all our systems in detail to see how they’d borne the unexpected strain. Mercifully, in view of the sour mood of the Big Boss, it turned out that the only thing we could have done better was buy a bigger pipe to and from the internet. We’d specified that ‘big pipe’ when designing the system. The Big Boss had then railed at the cost and so we’d subsequently compromised. I felt that my design decisions were vindicated. The Big Boss brooded for a while. Then he made the significant comment: “What really ****** me off is the fact that, for ten minutes, we couldn’t take people’s money.” At that point I stopped feeling smug. Had the internet connection been better, the system would have reached its limit and failed rather precipitously, and that wasn’t what he wanted. Then it occurred to me that what had gummed up the connection was all those images on the site, that had made it so impressive for the visitors. If there had been a way to automatically pare down the site to the bare essentials under stress… Hmm. I began to consider disaster-recovery in the broadest sense – maintaining a service in spite of unusual or unexpected events. What he said makes a lot of sense: sacrifice whatever isn’t essential to keep the core service running when we approach the capacity limits. Maybe in IT we should borrow (or revive) the business concept of the ‘Skeleton service’, maintaining only the priority parts under stress, using a process that is well-prepared and carefully rehearsed. How might this work? Whatever the event we have to prepare for, it is all about understanding the priorities; knowing what one can dispense with when the going gets tough. In the event of database disaster, it’s much faster to deploy a skeletal system with only the essential data than to restore the entire system, though there would have to be a reconciliation process to update the revived database retrospectively, once the emergency was over. It isn’t just the database that could be designed for resilience. One could prepare for unusually high traffic in a website by designing a system that degraded gradually to a ‘skeletal’ site, one that maintained the commercial essentials without fat images, JavaScript libraries and razzmatazz. This is all what the Big Boss scathingly called ‘a mere technicality’. It seems to me that what is needed first is a culture of application and database design which acknowledges that we live in a very imperfect world, and react accordingly when things go awry.

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  • I want to host clients' websites, but not their email. What's the easiest way to handle this?

    - by Phil
    My company lets non-technical users build their own niche industry websites on our server, which we host. they can currently point their nameservers at their registrar to us, which ends up with them no longer having access to their email if they've already set it up through said registrar. We don't want to interfere with their existing email, nor do we want to get into the business of setting up email for them through our service. Thus, having them point A records/cname to us would work, but is this too complex for a non-technie user? We thought of having them point nameservers to us but pointing the MX records back to them, but this is also beyond their scope. Is there an easy way to 'point records' at their initial state? Any other ideas/feedback?

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  • bad practice to create a print friendly page to remove the use of pdfs?

    - by Phil
    the company I work for has a one page invoice that uses the library tcpdf. they wanted to do some design changes that I found are just incredibly difficult for setting up in .pdf format. using html/css I could easily create the page and have it print very nicely, but I have a feeling that I am over looking something. is it a good practice to set up a page just for printing? and if not, is it at least better than putting out a ugly .pdf? I could also use the CSS inline so that if they wanted to download it and open it they could.

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  • Top down space game control problem

    - by Phil
    As the title suggests I'm developing a top down space game. I'm not looking to use newtonian physics with the player controlled ship. I'm trying to achieve a control scheme somewhat similar to that of FlatSpace 2 (awesome game). I can't figure out how to achieve this feeling with keyboard controls as opposed to mouse controls though. Any suggestions? I'm using Unity3d and C# or javaScript (unityScript or whatever is the correct term) works fine if you want to drop some code examples. Edit: Of course I should describe FlatSpace 2's control scheme, sorry. You hold the mouse button down and move the mouse in the direction you want the ship to move in. But it's not the controls I don't know how to do but rather the feeling of a mix of driving a car and flying an aircraft. It's really well made. Youtube link: FlatSpace2 on iPhone I'm not developing an iPhone game but the video shows the principle of the movement style. Edit 2 As there seems to be a slight interest, I'll post the version of the code I've used to continue. It works good enough. Sometimes good enough is sufficient! using UnityEngine; using System.Collections; public class ShipMovement : MonoBehaviour { public float directionModifier; float shipRotationAngle; public float shipRotationSpeed = 0; public double thrustModifier; public double accelerationModifier; public double shipBaseAcceleration = 0; public Vector2 directionVector; public Vector2 accelerationVector = new Vector2(0,0); public Vector2 frictionVector = new Vector2(0,0); public int shipFriction = 0; public Vector2 shipSpeedVector; public Vector2 shipPositionVector; public Vector2 speedCap = new Vector2(0,0); void Update() { directionModifier = -Input.GetAxis("Horizontal"); shipRotationAngle += ( shipRotationSpeed * directionModifier ) * Time.deltaTime; thrustModifier = Input.GetAxis("Vertical"); accelerationModifier = ( ( shipBaseAcceleration * thrustModifier ) ) * Time.deltaTime; directionVector = new Vector2( Mathf.Cos(shipRotationAngle ), Mathf.Sin(shipRotationAngle) ); //accelerationVector = Vector2(directionVector.x * System.Convert.ToDouble(accelerationModifier), directionVector.y * System.Convert.ToDouble(accelerationModifier)); accelerationVector.x = directionVector.x * (float)accelerationModifier; accelerationVector.y = directionVector.y * (float)accelerationModifier; // Set friction based on how "floaty" controls you want shipSpeedVector.x *= 0.9f; //Use a variable here shipSpeedVector.y *= 0.9f; //<-- as well shipSpeedVector += accelerationVector; shipPositionVector += shipSpeedVector; gameObject.transform.position = new Vector3(shipPositionVector.x, 0, shipPositionVector.y); } }

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  • Static pages for large photo album

    - by Phil P
    I'm looking for advice on software for managing a largish photo album for a website. 2000+ pictures, one-time drop (probably). I normally use MarginalHack's album, which does what I want: pre-generate thumbnails and HTML for the pictures, so I can serve without needing a dynamic run-time, so there's less attack surface to worry about. However, it doesn't handle pagination or the like, so it's unwieldy for this case. This is a one-time drop for pictures from a wedding, with a shared usercode/password for distribution to the guests; I don't wish to put the pictures in a third-party hosting environment. I don't wish to use PHP, simply because that's another run-time to worry about, I might relent and use something dynamic if it's Python or Perl based (as I can maintain things written in those). I currently have: Apache serving static files, Album-generated, some sub-directories to divide up the content to be a little more manageable. Something like Album but with pagination already handled would be great, but I'm willing to have something a little more dynamic, if it lets people comment or caption and store the extra data in something like an sqlite DB. I'd want something light-weight, not a full-blown CMS with security updates every three months. I don't want to upload pictures of other peoples' children into a third-party free service where I don't know what the revenue model is. (For my site: revenue is none, costs out of pocket). Existing server hosting is *nix, Apache, some WSGI. Client-side I have MacOS. Any advice?

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  • Why does my VertexDeclaration apparently not contain Position0?

    - by Phil
    I'm trying to get my code from calling each individual draw call down to using at least a VertexBuffer, and preferably an indexBuffer, but now that I'm attempting to test my code, I'm getting the error: The current vertex declaration does not include all the elements required by the current vertex shader. Position0 is missing. Which makes absolutely no sense to me, as my VertexDeclaration is: public readonly static VertexDeclaration VertexDeclaration = new VertexDeclaration( new VertexElement(0, VertexElementFormat.Vector3, VertexElementUsage.Position, 0), new VertexElement(sizeof(float) * 3, VertexElementFormat.Color, VertexElementUsage.Color, 0), new VertexElement(sizeof(float) * 3 + 4, VertexElementFormat.Vector3, VertexElementUsage.Normal, 0) ); Which clearly contains the information. I am attempting to draw with the following lines: VertexBuffer vb = new VertexBuffer(GraphicsDevice, VertexPositionColorNormal.VertexDeclaration, c.VertexList.Count, BufferUsage.WriteOnly); IndexBuffer ib = new IndexBuffer(GraphicsDevice, typeof(int), c.IndexList.Count, BufferUsage.WriteOnly); vb.SetData<VertexPositionColorNormal>(c.VertexList.ToArray()); ib.SetData<int>(c.IndexList.ToArray()); GraphicsDevice.DrawIndexedPrimitives(PrimitiveType.TriangleList, 0, 0, vb.VertexCount, 0, c.IndexList.Count/3); Where c is a Chunk class containing an 8x8x8 array of boxes. Full code is available at https://github.com/mrbaggins/Box/tree/ProperMeshing/box/box. Relevant locations are Chunk.cs (Contains the VertexDeclaration) and Game1.cs (Draw() is in Lines 230-250). Not much else of relevance to this problem anywhere else. Note that large commented sections are from old version of drawing.

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  • How to load a text file from a server into iPhone game with AS3 in Adobe AIR?

    - by Phil
    Im creating an iPhone game with Adobe AIR, and I want to be able to load a simple text msg into an dynamic text box on the games front screen from my server (and then be able to update that text file on the server, so it updates automatically in the game after the game is on the app store) How would I go about acheiving that? is it as simple as using a getURL? are there any specifical issues with trying to do this on the iPhone via AIR that I should be aware of? Thanks for any advice.

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  • Is it possible to give an animated GIF a transparent background?

    - by Phil
    I'm making a Fire Emblem-esque game. There are very cute 2D frames I made for each character, and, like a game like Fire Emblem, I want these characters to animate constantly. To circumvent the graphics programming involved I came up with a novel idea! I would make each character an animated gif, and only in special conditions ever halt their constant movement - in that case just change what image is being displayed. Simple enough. But I have a dilemma - I want the background of my .gifs to be transparent (so that the "grass" behind each character naturally shows, as per the screenshot - which has them as still images with transparent backgrounds). I know how to make a background transparent in numerous tools (GIMP, Photoshop). But it seems every .gif creator replaces the transparent background with something and I can't edit it back to transparent. Is it possible to have a .gif with a transparent "background"? Perhaps my knowledge of file formats is limiting me here.

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  • Chrome keeps crashing after updates

    - by Phil
    I'm a chrome user and an enthusiast but few days ago I made Ubuntu get some updates using Update Manager, then I turned off my notebook and when I restarted it, I tried to start Chrome which after a few seconds turned the screen completely black, and some errors appeared for few seconds and then I got logged off, and had to re-login, and when I opened Chrome again the same thing happened! I've uninstalled it with Synaptic and did complete cleanings before re-installing Chrome but nothing succeeded. Now I can't use either Chromium and Chrome, but Firefox works. It's a very strange thing, never happened to me before and I don't know what to do because I had all my bookmarks syncronized in Chrome! Please help if you can :)

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  • SQL Server 2008 - Management Studio issue

    - by Phil Streiff
    This is a known, documented issue with SQL Server 2008 Management Studio, but certain DDL operations like ALTERing a column datatype from Management Studio fails. For example, in Object Explorer, navigate to a table column > right-click on column > Modify. Then, change column datatype or length, then save and this error message displays: To workaround this problem, go to Query Editor and issue the following DDL statement instead:  TABLE dbo.FTPFile ALTER COLUMN CmdLine VARCHAR (100) ; ALTER   GO   The column change is successfuly applied now.

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  • What most games would benefit from having

    - by Phil
    I think I've seen "questions" like this on stackoverflow but sorry if I'm overstepping any bounds. Inspired by my recent question and all the nice answers (Checklist for finished game?) I think every gamedev out there has something he/she thinks that almost every game should have. That knowledge is welcome here! So this is probably going to be an inspirational subjective list of some sorts and the point is that anyone reading this question will see a point or two that they've overlooked in their own development and might benefit from adding. I think a good example might be: "some sort of manual or help section. Of course it should be proportional to how advanced the game is. Some users won't need it and won't go looking for it but the other ones that do will become very frustrated if they can't remember how to do something specific that should be in the manual". A bad example might be "good gameplay". Of course every game benefits from this but the answer is not very helpful.

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  • Best way to create neon glow line effect in AS3?

    - by Phil
    What's the best way to create a neon glow line effect in Flash AS3? Say similar to what's going on in the game gravitron360 on the xbox 360? Would it be a good idea to create movieclips with plain lines drawn in them and then apply a glow filter to them? or perhaps just apply the glow filter to the entire movieclip layer the movieclips are on? or just draw them manually and create a glow effect by converting the lines to fills and then softening edges? (wouldn't blend as well but would be the fastest CPU wise?) Thanks for any help

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