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• Merging two separate DNS zones

  - by cube

  This is a hypothetical question. Let's suppose I have two networks, each with its own DNS server. Network A has names a1.local, a2.local, ... and network B has b1.local, b2.local, .... Zone file for each of the networks looks something like this: $ORIGIN local @ IN SOA .... blah blah blah a1 A 1.2.3.4 a2 A 2.3.4.5 ... for A, and $ORIGIN local @ IN SOA .... blah blah blah b1 A 3.4.5.6 b2 A 4.5.6.7 ... for B. Now I also have a regular internet domain example.com and I want to access the machines as a1.A.example.com, b1.B.example.com, ... How will I have to change the configuration of name servers in networks A and B? (in fact I am writing a super-magic DNS server, currently serving A and B separately, but there is a chance that I will have to add the ability to merge the networks; so I'm interested in knowing the problems which lie ahead of me and how to prepare for the possibility)

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• Open source app to manage and run commands on cloud servers? [closed]

  - by Mark Theunissen

  I'm creating a SaaS platform, and I need a component / library that can create, delete and store the connection details for cloud servers. It also needs to support executing shell commands on these servers and returning the response to the caller. I want a central database of servers and their configuration, plus the ability to reach out and manage the servers via SSH execution of bash scripts. I don't want something that needs agents on every server like Chef. For example, this command is received by the hypothetical application: CREATE USER server = server12345 name = myuser It's translated into the following set of actions and executed by the app, which knows how to connect to server12345, and how to create a user on that server: $ ssh root@server12345 $ adduser myuser And returns the output from the shell: Added user myuser. I've done research on Google and can't quite quite find something that does this already. I've found: fabric This part handles the executing of the shell commands very elegantly, and can take multiple server definitions, but it's supposed to be a deployment tool so doesn't do everything that would be required above - for example, it doesn't have a daemon mode where it listens for commands - it expects to be executed on the shell. It also can't provide the central database functionality. libcloud This library can handle the server admin (CRUD) part, but doesn't have a command interface daemon either, and doesn't let you execute commands on the servers. I guess I need something that is a combination of libcloud, fabric and django for an API. Or something else that does that same thing regardless of language. Overmind Overmind is a GUI and wrapper around libcloud, but doesn't support the command execution part. What am I missing here?

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• Measuring Code Quality

  - by DotNetBlues

  Several months back, I was tasked with measuring the quality of code in my organization. Foolishly, I said, "No problem." I figured that Visual Studio has a built-in code metrics tool (Analyze -> Calculate Code Metrics) and that would be a fine place to start with. I was right, but also very wrong. The Visual Studio calculates five primary metrics: Maintainability Index, Cyclomatic Complexity, Depth of Inheritance, Class Coupling, and Lines of Code. The first two are figured at the method level, the second at (primarily) the class level, and the last is a simple count. The first question any reasonable person should ask is "Which one do I look at first?" The first question any manager is going to ask is, "What one number tells me about the whole application?" My answer to both, in a way, was "Maintainability Index." Why? Because each of the other numbers represent one element of quality while MI is a composite number that includes Cyclomatic Complexity. I'd be lying if I said no consideration was given to the fact that it was abstract enough that it's harder for some surly developer (I've been known to resemble that remark) to start arguing why a high coupling or inheritance is no big deal or how complex requirements are to blame for complex code. I should also note that I don't think there is one magic bullet metric that will tell you objectively how good a code base is. There are a ton of different metrics out there, and each one was created for a specific purpose in mind and has a pet theory behind it. When you've got a group of developers who aren't accustomed to measuring code quality, picking a 0-100 scale, non-controversial metric that can be easily generated by tools you already own really isn't a bad place to start. That sort of answers the question a developer would ask, but what about the management question; how do you dashboard this stuff when Visual Studio doesn't roll up the numbers to the solution level? Since VS does roll up the MI to the project level, I thought I could just figure out what sort of weighting Microsoft used to roll method scores up to the class level and then to the namespace and project levels. I was a bit surprised by the answer: there is no weighting. That means that a class with one 1300 line method (which will score a 0 MI) and one empty constructor (which will score a 100 MI) will have an overall MI of a respectable 50. Throw in a couple of DTOs that are nothing more than getters and setters (which tend to score 95 or better) and the project ends up looking really, really healthy. The next poor bastard who has to work on the application is probably not going to be singing the praises of its maintainability, though. For the record, that 1300 line method isn't a hypothetical, either. So, what does one do with that? Well, I decided to weight the average by the Lines of Code per method. For our above example, the formula for the class's MI becomes ((1300 * 0) + (1 * 100))/1301 = .077, rounded to 0. Sounds about right. Continue the pattern for namespace, project, solution, and even multi-solution application MI scores. This can be done relatively easily by using the "export to Excel" button and running a quick formula against the data. On the short list of follow-up questions would be, "How do I improve my application's score?" That's an answer for another time, though.

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• Ask the Readers: Would You Be Willing to Give Windows Up and Use a Different O.S.?

  - by Asian Angel

  When it comes to computers, Windows definitely rules the desktop in comparison to other operating systems. What we would like to know this week is if you would actually be willing to give up using Windows altogether and move to a different operating system on your computers. Note: This week’s Ask the Readers post is posing a hypothetical situation, so please refrain from starting arguments or a flame war in the comments. Good reasoned discussion is always welcome. There is no doubt that Windows is the dominant operating system in use today. Everywhere you go or look it is easy to find computers with Windows installed such as at work, home, the library, government offices, and more. For many people it is the operating system that they know and are comfortable with, which makes changing to a different operating system less appealing. Adding to the preference for Windows (or dependency based on your view) is the custom software that many businesses use on a daily basis. Throw in the high volume of people who depend on and use Microsoft Office as a standard for their business documents and it is little wonder that Windows is so dominant. So what would you use if you did decide to take a break from or permanently move away from Windows? If your choice is Linux then you have a large and wonderful variety of distributions to choose from based on what you want out of your system. Want a distribution that is easy to work with? You could choose Ubuntu, Linux Mint, or others that are engineered to be ready to go “out of the box”. Like a challenge? Perhaps Arch Linux is more your style. One of the most attractive features of all about Linux is the price…it is very hard to beat free! Maybe Mac OS X sounds like the perfect choice. It has a certain mystique and elegance associated with it and many OS X fans refuse to use anything else if given a choice. Then there is the soon to be released Chrome OS with its’ emphasis on cloud computing. This is a system that is definitely focused on being as low-maintenance and hassle-free as possible. Quick on, quick off, minimalist, and made to be portable. All of the system’s updates will occur automatically leaving you free to work and play in the cloud. But it does have its’ limitations…no installing all of those custom apps that you love using on Windows or other systems…it is literally all about the browsing window and web apps. So there you have it. If the opportunity presented itself would you, could you give Windows up and use a different operating system? Would it be easy or hard for you to do? Perhaps it would not really matter so long as you could do what you needed or wanted to do on a computer. And maybe this is the perfect time to try something new and find out…that new favorite operating system could be just an install disc away. Let us know your thoughts in the comments! How-To Geek Polls require Javascript. Please Click Here to View the Poll. Latest Features How-To Geek ETC The Complete List of iPad Tips, Tricks, and Tutorials The 50 Best Registry Hacks that Make Windows Better The How-To Geek Holiday Gift Guide (Geeky Stuff We Like) LCD? LED? Plasma? The How-To Geek Guide to HDTV Technology The How-To Geek Guide to Learning Photoshop, Part 8: Filters Improve Digital Photography by Calibrating Your Monitor The Brothers Mario – Epic Gangland Style Mario Brothers Movie Trailer [Video] Score Awesome Games on the Cheap with the Humble Indie Bundle Add a Colorful Christmas Theme to Your Windows 7 Desktop This Windows Hack Changes the Blue Screen of Death to Red Edit Images Quickly in Firefox with Pixlr Grabber Zoho Writer, Sheet, and Show Now Available in Chrome Web Store

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• Package Version Numbers, why are they so important

  - by Chris W Beal

  One of the design goals of IPS has been to allow people to easily move forward to a supported "Surface" of component. That is to say, when you  # pkg update your system, you get the latest set of components which all work together, based on the packages you already have installed. During development, this has meant simply you update to the latest "build" of the components. (During development, we build everything and publish everything every two weeks). Now we've released Solaris 11 using the IPS technologies, things are a bit more complicated. We need to be able to reflect all the types of Solaris release we are doing. For example Solaris Development builds, Solaris Update builds and "Support Repository Updates" (the replacement for patches) in the version scheme. So simply saying "151" as the build number isn't sufficient to articulate what you are running, or indeed what is available to update to In my previous blog post I talked about creating your own package, and gave an example FMRI of pkg://tools/[email protected],0.5.11-0.0.0 But it's probably more instructive to look at the FMRI of a Solaris package. The package "core-os" contains all the common utilities and daemons you need to use Solaris.  $ pkg info core-os Name: system/core-os Summary: Core Solaris Description: Operating system core utilities, daemons, and configuration files. Category: System/Core State: Installed Publisher: solaris Version: 0.5.11 Build Release: 5.11 Branch: 0.175.0.0.0.2.1 Packaging Date: Wed Oct 19 07:04:57 2011 Size: 25.14 MB FMRI: pkg://solaris/system/[email protected],5.11-0.175.0.0.0.2.1:20111019T070457Z The FMRI is what we will concentrate on here. In this package "solaris" is the publisher. You can use the pkg publisher command to see where the solaris publisher gets it's bits from $ pkg publisher PUBLISHER TYPE STATUS URI solaris origin online http://pkg.oracle.com/solaris/release/ So we can see we get solaris packages from pkg.oracle.com.  The package name is system/core-os. These can be arbitrary length, just to allow you to group similar packages together. Now on the the interesting? bit, the versions, everything after the @ is part of the version. IPS will only upgrade to a "higher" version. [email protected],5.11-0.175.0.0.0.2.1:20111019T070457Z core-os = Package Name0.5.11 = Component - in this case we're saying it's a SunOS 5.11 package, = separator5.11 = Built on version - to indicate what OS version you built the package on- = another separator0.175.0.0.0.2.1 = Branch Version : = yet another separator20111019T070457Z = Time stamp when the package was published So from that we can see the Branch Version seems rather complex. It is necessarily so, to allow us to describe the hierachy of releases we do In this example we see the following 0.175: is known as the trunkid, and is incremented each build of a new release of Solaris. During Solaris 11 this should not change  0: is the Update release for Solaris. 0 for FCS, 1 for update 1 etc 0: is the SRU for Solaris. 0 for FCS, 1 for SRU 1 etc 0: is reserved for future use 2: Build number of the SRU 1: Nightly ID - only important for Solaris developersTake a hypothetical example [email protected],5.11-0.175.1.5.0.4.1:<something> This would be build 4 of SRU 5 of Update 1 of Solaris 11 This is actually documented in a MOS article 1378134.1 Which you can read if you have a support contract.

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• ARTS Reference Model for Retail

  - by Sanjeev Sharma

  Consider a hypothetical scenario where you have been tasked to set up retail operations for a electronic goods or daily consumables or a luxury brand etc. It is very likely you will be faced with the following questions: What are the essential business capabilities that you must have in place?  What are the essential business activities under-pinning each of the business capabilities, identified in Step 1? What are the set of steps that you need to perform to execute each of the business activities, identified in Step 2? Answers to the above will drive your investments in software and hardware to enable the core retail operations. More importantly, the choices you make in responding to the above questions will several implications in the short-run and in the long-run. In the short-term, you will incur the time and cost of defining your technology requirements, procuring the software/hardware components and getting them up and running. In the long-term, as you grow in operations organically or through M&A, partnerships and franchiser business models  you will invariably need to make more technology investments to manage the greater complexity (scale and scope) of business operations.  "As new software applications, such as time & attendance, labor scheduling, and POS transactions, just to mention a few, are introduced into the store environment, it takes a disproportionate amount of time and effort to integrate them with existing store applications. These integration projects can add up to 50 percent to the time needed to implement a new software application and contribute significantly to the cost of the overall project, particularly if a systems integrator is called in. This has been the reality that all retailers have had to live with over the last two decades. The effect of the environment has not only been to increase costs, but also to limit retailers' ability to implement change and the speed with which they can do so." (excerpt taken from here) Now, one would think a lot of retailers would have already gone through the pain of finding answers to these questions, so why re-invent the wheel? Precisely so, a major effort began almost 17 years ago in the retail industry to make it less expensive and less difficult to deploy new technology in stores and at the retail enterprise level. This effort is called the Association for Retail Technology Standards (ARTS). Without standards such as those defined by ARTS, you would very likely end up experiencing the following: Increased Time and Cost due to resource wastage arising from re-inventing the wheel i.e. re-creating vanilla processes from scratch, and incurring, otherwise avoidable, mistakes and errors by ignoring experience of others Sub-optimal Process Efficiency due to narrow, isolated view of processes thereby ignoring process inter-dependencies i.e. optimizing parts but not the whole, and resulting in lack of transparency and inter-departmental finger-pointing Embracing ARTS standards as a blue-print for establishing or managing or streamlining your retail operations can benefit you in the following ways: Improved Time-to-Market from parity with industry best-practice processes e.g. ARTS, thus avoiding “reinventing the wheel” for common retail processes and focusing more on customizing processes for differentiations, and lowering integration complexity and risk with a standardized vocabulary for exchange between internal and external i.e. partner systems Lower Operating Costs by embracing the ARTS enterprise-wide process reference model for developing and streamlining retail operations holistically instead of a narrow, silo-ed view, and  procuring IT systems in compliance with ARTS thus avoiding IT budget marginalization While parity with industry standards such as ARTS business process model by itself does not create a differentiation, it does however provide a higher starting point for bridging the strategy-execution gap in setting up and improving retail operations.

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• CI tests to enforce specific development rules - good practice?

  - by KeithS

  The following is all purely hypothetical and any particular portion of it may or may not accurately describe real persons or situations, whether living, dead or just pretending. Let's say I'm a senior dev or architect in charge of a dev team working on a project. This project includes a security library for user authentication/authorization of the application under development. The library must be available for developers to edit; however, I wish to "trust but verify" that coders are not doing things that could compromise the security of the finished system, and because this isn't my only responsibility I want it to be done in an automated way. As one example, let's say I have an interface that represents a user which has been authenticated by the system's security library. The interface exposes basic user info and a list of things the user is authorized to do (so that the client app doesn't have to keep asking the server "can I do this?"), all in an immutable fashion of course. There is only one implementation of this interface in production code, and for the purposes of this post we can say that all appropriate measures have been taken to ensure that this implementation can only be used by the one part of our code that needs to be able to create concretions of the interface. The coders have been instructed that this interface and its implementation are sacrosanct and any changes must go through me. However, those are just words; the security library's source is open for editing by necessity. Any of my devs could decide that this secured, private, hash-checked implementation needs to be public so that they could do X, or alternately they could create their own implementation of this public interface in a different library, exposing the hashing algorithm that provides the secure checksum, in order to do Y. I may not be made aware of these changes so that I can beat the developer over the head for it. An attacker could then find these little nuggets in an unobfuscated library of the compiled product, and exploit it to provide fake users and/or falsely-elevated administrative permissions, bypassing the entire security system. This possibility keeps me awake for a couple of nights, and then I create an automated test that reflectively checks the codebase for types deriving from the interface, and fails if it finds any that are not exactly what and where I expect them to be. I compile this test into a project under a separate folder of the VCS that only I have rights to commit to, have CI compile it as an external library of the main project, and set it up to run as part of the CI test suite for user commits. Now, I have an automated test under my complete control that will tell me (and everyone else) if the number of implementations increases without my involvement, or an implementation that I did know about has anything new added or has its modifiers or those of its members changed. I can then investigate further, and regain the opportunity to beat developers over the head as necessary. Is this considered "reasonable" to want to do in situations like this? Am I going to be seen in a negative light for going behind my devs' backs to ensure they aren't doing something they shouldn't?

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• The World of SQL Database Deployment

  - by GGBlogger

  In my early development days, I used Microsoft Access for building databases. It made things easy since I only needed to package the database with the installation package so my clients would have access to it. When we began the development of a new package in Visual Studio .NET I decided to use SQL Server Express. It was free and provided good tools - also free. I thought it was a tremendous idea until it came time to distribute our new software! What a surprise. The nightmare Ah, the choices! Detach the database and have the client reattach it to a newly installed – oh wait. FIRST my new client needs to download and install SQL Server Express with SQL Server Management Studio. That’s not a great thing, but it is one more nightmare step for users who may have other versions of SQL installed. Then the question became – do we detach and reattach or do we do a backup. It was too late (bad planning) to revert to Microsoft Access but we badly needed a simple way to package and distribute both the database AND sample contents. Red Gate to the rescue It took me a while to find an answer but I did find it in a package called SQL Packager sold by a relatively unpublicized company in England called Red Gate. They call their products “ingeniously simple” and I must agree with that description. With SQL Packager you point to the database (more in a minute) you want to distribute. A few mouse clicks and dialogs and you have an executable file that you can ship virtually anywhere and virtually any way which, when run, installs the database on your destination SQL Server instance! It really is that simple. Easier to show than tell Let’s explore a hypothetical case. Let’s say you have a local SQL database of customers and you have decided you want to share it with your subsidiaries or partners. Here is the underlying screen you will see on starting SQL Packager. There are a bunch of possibilities here but I’m going to keep this relatively simple. At this point I simply want to illustrate the simplicity of generating an executable to deliver your database. You will notice that you can set up a new package, edit an existing package or change a bunch of options. Start SQL packager And the following is the default dialog you get on startup. In the next dialog, I’ve selected the Server and Database. I’ve also selected Windows Authentication. Pressing Next causes SQL Packager to run a number of checks and produce a report. Now you’re given a comprehensive list of what is going to be packaged and you’re allowed to change it if you desire. I’ve never made any changes here so I can’t really make any suggestions. The just illustrates the comprehensive nature of so many Red Gate products including this one. Clicking Next gives you still further options. SQL Packager then works its magic and shows you a dialog with the results. Packager then gives you a dialog of the scripts it has generated. The capture above only shows 1 of 4 tabs. Finally pressing Next gives you the option to generate a .NET executable of a C# project. I’ve only generated an executable so I’m not in a position to tell you what the C# project looks like. That may be the subject of further discussions. You can rename the package and tell SQL Packager where to save it. I’ve skipped a lot but this will serve to illustrate the comprehensive (and ingenious) things Red Gate does. All in all, it’s a superb way to distribute populated SQL databases. Oh – we’ll save running the resulting executable for later also but believe me it’s insanely simple.

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• FullCalendar and events: function

  - by Ernest

  I am trying to display my events from a MySQL database. I'm using the events function. My XML file being returned is pretty basic. I've looked at all of the FullCalendar questions and most of them talk about JSON and point to the documentation for JSON. I can't use JSON. I have to go XML. Can you tell me where I'm off. Here is a sample of what my xml looks like: Grow Your Business on the Web 2010-06-05T9:30 2010-06-05T12:30 O The whole file is prefaced with a tag and closed with a tag. My jquery is as follows: $(document).ready(function() { $('#calendar').fullCalendar({ height: 550, theme: true, header: { left: 'prev,next today', center: 'title', right: 'month,agendaWeek,agendaDay' }, editable: true, events: function(start, end, callback) { $.ajax({ url: 'ncludeFiles/sbdp-cal-xml.php', dataType: 'xml', data: { // our hypothetical feed requires UNIX timestamps start: Math.round(start.getTime() / 1000), end: Math.round(end.getTime() / 1000) }, success: function(doc) { var events = []; $(doc).find('event').each(function() { events.push({ title: $(this).attr('title'), start: $(this).attr('start'), end: $(this).attr('end'), className: $(this).attr('className'), url: $(this).attr('url') }); }); callback(events); } }); } }); }); I'd appreciate any help you could give me. Thanks!

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• what type of bug causes a program to slowly use more processor power and all of a sudden go to 100%?

  - by reinier

  Hi, I was hoping to get some good ideas as to what might be causing a really nasty bug. This is a program which is transmitting data over a socket, and also receives messages back. I could explain lots more, but I don't think this will help here. I'm just searching for hypothetical problems which can cause the following behaviour: program runs processor time slowly accumulates (till around 60%) all of a sudden (could be after 30 but also after 60 seconds) the processor time shoots to 100%. the program halts completely In my syslog it always ends on one line with a memory allocation (something similar to: myArray = new byte[16384]) in the same thread. now here is the weird part: if I set the debugger anywhere...it immediately stops on that line. So just the act of setting a breakpoint, made the thread continue (it wasn't running since I saw no log output anymore) I was thinking 'deadlock' but that would not cause 100% processor power. If anything, the opposite. Also, setting a breakpoint would not cause a deadlock to end. anyone else a theoretical suggestion as to what kind of 'construct' might cause this effect? (apart from 'bad programming') ;^) thanks EDIT: I just noticed.... by setting the sendspeed slower, the problem shows itself much later than expected. I would think around the same amount of packets send...but no the amount of packets send is much higher this way before it has the same problem.

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• Proof of library bug vs developer side application bug

  - by Paralife

  I have a problem with a specific java client library. I wont say here the problem or the name of the library because my question is a different one. Here is the situation: I have made a program that uses the library. The program is a class named 'WorkerThread' that extends Thread. To start it I have made a Main class that only contains a main() function that starts the thread and nothing else. The worker uses the library to perform comm with a server and get results. The problem appears when I want to run 2 WorkerThreads simultaneously. What I first did was to do this in the Main class: public class Main { public static void main(String args[]) { new WorkerThread().start(); // 1st thread. new WorkerThread().start(); // 2nd thread. } } When I run this, both threads produce irrational results and what is more , some results that should be received by 1st thread are received by the 2nd instead. If instead of the above, I just run 2 separate processes of one thread each, then everything works fine. Also: 1.There is no static class or method used inside WorkerThread that could cause the problem. My application consists of only the worker thread class and contains no static fields or methods 2.The library is supposed to be usable in a multithreaded environment. In my thread I just create a new instance of a library's class and then call methods on it. Nothing more. My question is this: Without knowing any details of my implementation, is the above situation and facts enough to prove that there is a bug in the library and not in my programm? Is it safe to assume that the library inside uses a static method or object that is indirectly shared by my 2 threads and this causes the problem? If no then in what hypothetical situation could the bug originate in the worker class code?

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• Invalidating Memcached Keys on save() in Django

  - by Zack

  I've got a view in Django that uses memcached to cache data for the more highly trafficked views that rely on a relatively static set of data. The key word is relatively: I need invalidate the memcached key for that particular URL's data when it's changed in the database. To be as clear as possible, here's the meat an' potatoes of the view (Person is a model, cache is django.core.cache.cache): def person_detail(request, slug): if request.is_ajax(): cache_key = "%s_ABOUT_%s" % settings.SITE_PREFIX, slug # Check the cache to see if we've already got this result made. json_dict = cache.get(cache_key) # Was it a cache hit? if json_dict is None: # That's a negative Ghost Rider person = get_object_or_404(Person, display = True, slug = slug) json_dict = { 'name' : person.name, 'bio' : person.bio_html, 'image' : person.image.extra_thumbnails['large'].absolute_url, } cache.set(cache_key) # json_dict will now exist, whether it's from the cache or not response = HttpResponse() response['Content-Type'] = 'text/javascript' response.write(simpljson.dumps(json_dict)) # Make sure it's all properly formatted for JS by using simplejson return response else: # This is where the fully templated response is generated What I want to do is get at that cache_key variable in it's "unformatted" form, but I'm not sure how to do this--if it can be done at all. Just in case there's already something to do this, here's what I want to do with it (this is from the Person model's hypothetical save method) def save(self): # If this is an update, the key will be cached, otherwise it won't, let's see if we can't find me try: old_self = Person.objects.get(pk=self.id) cache_key = # Voodoo magic to get that variable old_key = cache_key.format(settings.SITE_PREFIX, old_self.slug) # Generate the key currently cached cache.delete(old_key) # Hit it with both barrels of rock salt # Turns out this doesn't already exist, let's make that first request even faster by making this cache right now except DoesNotExist: # I haven't gotten to this yet. super(Person, self).save() I'm thinking about making a view class for this sorta stuff, and having functions in it like remove_cache or generate_cache since I do this sorta stuff a lot. Would that be a better idea? If so, how would I call the views in the URLconf if they're in a class?

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• Best and easiest algorithm to search for a vertex on a Graph?

  - by Nazgulled

  Hi, After implementing most of the common and needed functions for my Graph implementation, I realized that a couple of functions (remove vertex, search vertex and get vertex) don't have the "best" implementation. I'm using adjacency lists with linked lists for my Graph implementation and I was searching one vertex after the other until it finds the one I want. Like I said, I realized I was not using the "best" implementation. I can have 10000 vertices and need to search for the last one, but that vertex could have a link to the first one, which would speed up things considerably. But that's just an hypothetical case, it may or may not happen. So, what algorithm do you recommend for search lookup? Our teachers talked about Breadth-first and Depth-first mostly (and Dikjstra' algorithm, but that's a completely different subject). Between those two, which one do you recommend? It would be perfect if I could implement both but I don't have time for that, I need to pick up one and implement it has the first phase deadline is approaching... My guess, is to go with Depth-first, seems easier to implement and looking at the way they work, it seems a best bet. But that really depends on the input. But what do you guys suggest?

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• Relational database data explorer / visualization?

  - by Ian Boyd

  Is there a tool that can let one browse relational data as a graph of connected nodes? For example, i'm faced with trying to cleanse some anomolous data. i can start with two offending rows. In this particular example, the TransactionID should, by business rules, be unique to the table, but i find a transaction that violates that rule: SELECT * FROM LCTTrans WHERE TransactionID = 1075048 LCTID TransactionID ========= ============= 4358 1075048 4359 1075048 2 row(s) affected But really what i want to begin to hunt down all the related data, to try to see which is right. So this hypothetical software would start by showing me these two rows: Next, i want to see that transaction that is linked into this table: Now that transaction points to an MAL, so show me that: Now lets add those two LCTs, that the transaction is "on". A transaction can be on only one LCT, yet this one is pointing to two: Okay computer, both of those LCTs point to an MAL and the transaction that created them, show me those: Those last two transactions, they also point at an MAL, and they themselves point to an LCT, show me those: Okay, now are there any entries in LCTTrans that point to LCTs 4358 or 4359?... And so on, and so on. Now i did all this manually, running single selects, copying and pasting uniqueidentifier keys and converting them into friendly id numbers so i could easily see the relationships. Is there software that can do this?

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• Ideas for a rudimentary software licensing implementation

  - by Ross

  I'm trying to decide how to implement a very basic licensing solution for some software I wrote. The software will run on my (hypothetical) clients' machines, with the idea being that the software will immediately quit (with a friendly message) if the client is running it on greater-than-n machines (n being the number of licenses they have purchased). Additionally, the clients are non-tech-savvy to the point where "basic" is good enough. Here is my current design, but given that I have little to no experience in the topic, I wanted to ask SO before I started any development on it: A remote server hosts a MySQL database with a table containing two columns: client-key and license quantity The client-side application connects to the MySQL database on startup, offering it's client-key that I've put into a properties file packaged into the distribution (I would create a new distribution for each new client) Chances are, I'll need a second table to store validation history, so that with some short logic, the software can decide if it can be run on a given machine (maybe a sliding window of n machines using the software per 24 hours) If the software cannot establish a connection to the MySQL database, or decides that it's over the n allowed machines per day, it closes The connection info for the remote server hosting the MySQL database should be hard-coded into the app? (That sounds like a bad idea, but otherwise they could point it to some other always-validates-to-success server) I think that about covers my initial design. The intent being that while it certainly isn't full-proof, I think I've made it at least somewhat difficult to create an easily-sharable cracking solution. Also, I can easily adjust the license amount for a given client/key pair. I gotta figure this has been done a million times before, so tell me about a better solution that's just as simple to implement and provides the same (low) amount of security. In the event that external libraries are used, I prefer Java, as that's what the software has been written in.

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• How do I use a modalViewController Identically in Two Controllers?

  - by Theory

  I'm using the Three20 TTMessageController in my app. I've figured out how to use it, adding on a bunch of other stuff (including TTMessageControllerDelegate methods and ABPeoplePickerNavigationControllerDelegate methods). It works great for me, after a bit of a struggle to figure it out. The trouble I'm having now is a design issue: I want to use it identically in two different places, including with the same delegate methods. My current approach is that I've put all the code into a single class inheriting from NSObject, called ComposerProxy, and I'm just having the two controllers that use it use the proxy, like so: ComposerProxy *proxy = [[ComposerProxy alloc] initWithController:this]; [proxy go]; The go method constructs the TTMessageController, configures it, adds it to a UINavigationController, and presents it: [self.controller presentModalViewController: navController animated: YES]; This works great, as I have all my code nicely encapsulated in ComposerProxy and I need only the above two lines anywhere I want to use it. The downside, though, is that I can't dealloc the proxy variable without getting crashes. I can't autorelease it, either: same problem. So I'm wondering if my proxy approach is a poor one. How does one normally encapsulate a bunch of behaviors like this without requiring a lot of duplicate code in the classes that use it? Do I need to add a delegate class to my ComposerProxy and make the controller responsible for dismissing the modal view controller in a hypothetical composerDidFinish method or some such? Many TIA!

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• Perl: remove relative path components?

  - by jnylen

  I need to get Perl to remove relative path components from a Linux path. I've found a couple of functions that almost do what I want, but: File::Spec->rel2abs does too little. It does not resolve ".." into a directory properly. Cwd::realpath does too much. It resolves all symbolic links in the path, which I do not want. Perhaps the best way to illustrate how I want this function to behave is to post a bash log where FixPath is a hypothetical command that gives the desired output: '/tmp/test'$ mkdir -p a/b/c1 a/b/c2 '/tmp/test'$ cd a '/tmp/test/a'$ ln -s b link '/tmp/test/a'$ ls b link '/tmp/test/a'$ cd b '/tmp/test/a/b'$ ls c1 c2 '/tmp/test/a/b'$ FixPath . # rel2abs works here ===> /tmp/test/a/b '/tmp/test/a/b'$ FixPath .. # realpath works here ===> /tmp/test/a '/tmp/test/a/b'$ FixPath c1 # rel2abs works here ===> /tmp/test/a/b/c1 '/tmp/test/a/b'$ FixPath ../b # realpath works here ===> /tmp/test/a/b '/tmp/test/a/b'$ FixPath ../link/c1 # neither one works here ===> /tmp/test/a/link/c1 '/tmp/test/a/b'$ FixPath missing # should work for nonexistent files ===> /tmp/test/a/b/missing

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• Is it possible to use boost::bind to effectively concatenate functions?

  - by Catskul

  Assume that I have a boost::function of with an arbitrary signature called type CallbackType. Is it possible to use boost::bind to compose a function that takes the same arguments as the CallbackType but calls the two functors in succession? Hypothetical example using a magic template: Template<typename CallbackType> class MyClass { public: CallbackType doBoth; MyClass( CallbackType callback ) { doBoth = bind( magic<CallbackType>, protect( bind(&MyClass::alert, this) ), protect( callback ) ); } void alert() { cout << "It has been called\n"; } }; void doIt( int a, int b, int c) { cout << "Doing it!" << a << b << c << "\n"; } int main() { typedef boost::function<void (int, int, int)> CallbackType; MyClass<CallbackType> object( boost::bind(doIt) ); object.doBoth(); return 0; }

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• What are the benefits of the PHP the different PHP compression libraries?

  - by Christopher W. Allen-Poole

  I've been looking into ways to compress PHP libraries, and I've found several libraries which might be useful, but I really don't know much about them. I've specifically been reading about bcompiler and PHAR libraries. Is there any performance benefit in either of these? Are there any "gotchas" I need to watch out for? What are the relative benefits? Do either of them add to/detract from performance? I'm also interested in learning of other libs which might be out there which are not obvious in the documentation? As an aside, does anyone happen to know whether these work more like zip files which just happen to have the code in there, or if they operate more like Python's pre-compiling which actually runs a pseudo-compiler? ======================= EDIT ======================= I've been asked, "What are you trying to accomplish?" Well, I suppose the answer is that this is all hypothetical. It is a combination of these: What if my pet project becomes the most popular web project on earth and I want to distribute it quickly and easily? (hay, a man can dream, right?) It also seems if using PHAR can be done easily, it would be the best way to create a subversion snapshot. Python has this really cool pre-compiling policy, I wonder if PHP has something like that? These libraries seem to do something similar. Will they do that? Hey, these libraries seem pretty neat, but I'd like clarification on the differences as they seem to do the same thing

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• What is the best anti-crack scheme for your trial or subscription software?

  - by gmatt

  Writing code takes time and effort and just like any other human being we need to live by making an income (save for the few that are actually self sustainable.) Here are 3 general schemes to make a living: Independent developers can offer a trial then purchase scheme. An alternative is an open source base application with pay extensions. A last (probably least popular with customers) scheme is to enforce some kind of subscription. Then the price of the software pales in comparison to the long term subscription fees. So, my question would be a hypothetical one. Suppose that you invest thousands of hours into developing an application. Now suppose you can choose any one of the three options to make a living off this application--or any other option you want--and suppose you have a very real fear of loosing 80% of your revenue to a cracked version if one can be made. To be clear this application does not require the internet to perform all its useful functions, that is, your application is a prime candidate to be a cracked release on some website. Which option would you feel most comfortable with defending yourself against this possible situation and briefly describe why this option would be the best.

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• Natural vs surrogate keys on support tables

  - by Bugeo

  I have read many articles about the battle between natural versus surrogate primary keys. I agree in the use of surrogate keys to identify records of tables whose contents are created by the user. But in the case of supporting tables what should I use? For example, in a hypothetical table "orderStates". If you use a natural key would have the following data: TABLE ORDERSTATES {ID: "NEW", NAME: "New"} {ID: "MANAGEMENT" NAME: "Management"} {ID: "SHIPPED" NAME: "Shipped"} If I use a surrogate key would have the following data: TABLE ORDERSTATES {ID: 1 CODE: "NEW", NAME: "New"} {ID: 2 CODE: "MANAGEMENT" NAME: "Management"} {ID: 3 CODE: "SHIPPED" NAME: "Shipped"} Now let's take an example: a user enters a new order. In the case in which use natural keys, in the code I can write this: newOrder.StateOrderId = "NEW"; With the surrogate keys instead every time I have an additional step. stateOrderId_NEW = .... I retrieve the id corresponding to the recod code "NEW" newOrder.StateOrderId = stateOrderId_NEW; The same will happen every time I have to move the order in a new status. So, in this case, what are the reason to chose one key type vs the other one?

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• Perl: remove relative path components but leave symlinks alone?

  - by jnylen

  I need to get Perl to remove relative path components from a Linux path. I've found a couple of functions that almost do what I want, but: File::Spec->rel2abs does too little. It does not resolve ".." into a directory properly. Cwd::realpath does too much. It resolves all symbolic links in the path, which I do not want. Perhaps the best way to illustrate how I want this function to behave is to post a bash log where FixPath is a hypothetical command that gives the desired output: '/tmp/test'$ mkdir -p a/b/c1 a/b/c2 '/tmp/test'$ cd a '/tmp/test/a'$ ln -s b link '/tmp/test/a'$ ls b link '/tmp/test/a'$ cd b '/tmp/test/a/b'$ ls c1 c2 '/tmp/test/a/b'$ FixPath . # rel2abs works here ===> /tmp/test/a/b '/tmp/test/a/b'$ FixPath .. # realpath works here ===> /tmp/test/a '/tmp/test/a/b'$ FixPath c1 # rel2abs works here ===> /tmp/test/a/b/c1 '/tmp/test/a/b'$ FixPath ../b # realpath works here ===> /tmp/test/a/b '/tmp/test/a/b'$ FixPath ../link/c1 # neither one works here ===> /tmp/test/a/link/c1 '/tmp/test/a/b'$ FixPath missing # should work for nonexistent files ===> /tmp/test/a/b/missing

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• Rails - Seeking a Dry authorization method compatible with various nested resources

  - by adam

  Consensus is you shouldn't nest resources deeper than 1 level. So if I have 3 models like this (below is just a hypothetical situation) User has_many Houses has_many Tenants and to abide by the above i do map.resources :users, :has_many => :houses map.resorces :houses, :has_many => :tenants Now I want the user to be able edit both their houses and their tenants details but I want to prevent them from trying to edit another users houses and tenants by forging the user_id part of the urls. So I create a before_filter like this def prevent_user_acting_as_other_user if User.find_by_id(params[:user_id]) != current_user() @current_user_session.destroy flash[:error] = "Stop screwing around wiseguy" redirect_to login_url() return end end for houses that's easy because the user_id is passed via edit_user_house_path(@user, @house) but in the tenents case tenant house_tenent_path(@house) no user id is passed. But I can get the user id by doing @house.user.id but then id have to change the code above to this. def prevent_user_acting_as_other_user if params[:user_id] @user = User.find(params[:user_id] elsif params[:house_id] @user = House.find(params[:house_id]).user end if @user != current_user() #kick em out end end It does the job, but I'm wondering if there is a more elegant way. Every time I add a new resource that needs protecting from user forgery Ill have to keep adding conditionals. I don't think there will be many cases but would like to know a better approach if one exists.

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• [Delphi] How would you refactor this code?

  - by Al C

  This hypothetical example illustrates several problems I can't seem to get past, even though I keep trying!! ... Suppose the original code is a long event handler, coded in the UI, triggered when a user clicks a cell in a grid. Expressed as pseudocode it's: if Condition1=true then begin //loop through every cell in row, //if aCell/headerCellValue>1 then //color aCell red end else if Condition2=true then begin //do some other calculation adding cell and headerCell values, and //if some other product>2 then //color the whole row green end else show an error message I look at this and say "Ah, refactor to the strategy pattern! The code will be easier to understand, easier to debug, and easier to later extend!" I get that. And I can easily break the code into multiple procedures. The problem is ultimately scope related. Assume the pseudocode makes extensive use of grid properties, values displayed in cells, maybe even built-in grid methods. How do you move all that to another unit, without referencing the grid component in the UI--which would break all the "rules" about loose coupling that make OOP valuable? ... I'm really looking forward to responses. Thanks, as always -- Al C.

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• Selecting first instance of class but not nested instances via jQuery

  - by DA

  Given the following hypothetical markup: <ul class="monkey"> <li> <p class="horse"></p> <p class="cow"></p> </li> </ul> <dl class="monkey"> <dt class="horse"></dt> <dd class="cow"> <dl> <dt></dt> <dd></dd> </dl> <dl class="monkey"> <dt class="horse"></dt> <dd class="cow"></dd> </dl> </dd> </dl> I want to be able to grab the 'first level' of horse and cow classes within each monkey class. But I don't want the NESTED horse and cow classes. I started with .children, but that won't work with the UL example as they aren't direct children of .monkey. I can use find: $('.monkey').find('.horse, .cow') but that returns all instances, including the nested ones. I can filter the find: $('.monkey').find('.horse, .cow').not('.cow .horse, .cow .cow') but that prevents me from selecting nested instances on a second function call. So...I guess what I'm looking for is 'find first "level" of this descendant'. I could likely do this with some looping logic, but was wondering if there is a selector and/or some combo of selectors that would achieve that logic.

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