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  • Design Pattern for building a Budget

    - by Scott
    So I've looked at the Builder Pattern, Abstract Interfaces, other design patterns, etc. - and I think I'm over thinking the simplicity behind what I'm trying to do, so I'm asking you guys for some help with either recommending a design pattern I should use, or an architecture style I'm not familiar with that fits my task. So I have one model that represents a Budget in my code. At a high level, it looks like this: public class Budget { public int Id { get; set; } public List<MonthlySummary> Months { get; set; } public float SavingsPriority { get; set; } public float DebtPriority { get; set; } public List<Savings> SavingsCollection { get; set; } public UserProjectionParameters UserProjectionParameters { get; set; } public List<Debt> DebtCollection { get; set; } public string Name { get; set; } public List<Expense> Expenses { get; set; } public List<Income> IncomeCollection { get; set; } public bool AutoSave { get; set; } public decimal AutoSaveAmount { get; set; } public FundType AutoSaveType { get; set; } public decimal TotalExcess { get; set; } public decimal AccountMinimum { get; set; } } To go into more detail about some of the properties here shouldn't be necessary, but if you have any questions about those I will fill more out for you guys. Now, I'm trying to create code that builds one of these things based on a set of BudgetBuildParameters that the user will create and supply. There are going to be multiple types of these parameters. For example, on the sites homepage, there will be an example section where you can quickly see what your numbers look like, so they would be a much simpler set of SampleBudgetBuildParameters then say after a user registers and wants to create a fully filled out Budget using much more information in the DebtBudgetBuildParameters. Now a lot of these builds are going to be using similar code for certain tasks, but might want to also check the status of a users DebtCollection when formulating a monthly spending report, where as a Budget that only focuses on savings might not want to. I'd like to reduce code duplication (obviously) as much as possible, but in my head, every way I can think to do this would require using a base BudgetBuilderFactory to return the correct builder to the caller, and then creating say a SimpleBudgetBuilder that inherits from a BudgetBuilder, and put all duplicate code in the BudgetBuilder, and let the SimpleBudgetBuilder handle it's own cases. Problem is, a lot of the unique cases are unique to 2/4 builders, so there will be duplicate code somewhere in there obviously if I did that. Can anyone think of a better way to either explain a solution to this that may or may not be similar to mine, or a completely different pattern or way of thinking here? I really appreciate it.

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  • Online modelling tool for server desing / architecture

    - by 2ge
    I am looking for some online (the best is free) tool for designing our servers. We use almost 10 servers now, and it becoming mess, to remember, where, what service is running. So, I'd like to have some online modeling tool, where I can set up things like: - server host - server hw parameters - server os - server services with running programs I am looking for server designing tool like online SQL modeling on http://ondras.zarovi.cz/sql/demo/?keyword=default (WWW SQL designer) Any ideas ?

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  • How are "Json.org"-like specs graphs called and how can I generate them?

    - by Sebastián Grignoli
    In http://www.json.org Douglas Crockford shows the specs of the JSON format in two interesting ways: In the right side column he lists a text spec that looks like a YACC or LEX listing. In the main body of the homepage, he put several images that gives us a simple way to visually understand the valid sequences that composes a JSON string. Those images look like a description of the path that a finite state automaton would follow when parsing the JSON string. Wich are the names (if any) of that listing format and that kind of graphics? Is there any software that renders a source file containing the specification into that kind of images?

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  • Looking for a real-world example illustrating that composition can be superior to inheritance

    - by Job
    I watched a bunch of lectures on Clojure and functional programming by Rich Hickey as well as some of the SICP lectures, and I am sold on many concepts of functional programming. I incorporated some of them into my C# code at a previous job, and luckily it was easy to write C# code in a more functional style. At my new job we use Python and multiple inheritance is all the rage. My co-workers are very smart but they have to produce code fast given the nature of the company. I am learning both the tools and the codebase, but the architecture itself slows me down as well. I have not written the existing class hierarchy (neither would I be able to remember everything about it), and so, when I started adding a fairly small feature, I realized that I had to read a lot of code in the process. At the surface the code is neatly organized and split into small functions/methods and not copy-paste-repetitive, but the flip side of being not repetitive is that there is some magic functionality hidden somewhere in the hierarchy chain that magically glues things together and does work on my behalf, but it is very hard to find and follow. I had to fire up a profiler and run it through several examples and plot the execution graph as well as step through a debugger a few times, search the code for some substring and just read pages at the time. I am pretty sure that once I am done, my resulting code will be short and neatly organized, and yet not very readable. What I write feels declarative, as if I was writing an XML file that drives some other magic engine, except that there is no clear documentation on what the XML should look like and what the engine does except for the existing examples that I can read as well as the source code for the 'engine'. There has got to be a better way. IMO using composition over inheritance can help quite a bit. That way the computation will be linear rather than jumping all over the hierarchy tree. Whenever the functionality does not quite fit into an inheritance model, it will need to be mangled to fit in, or the entire inheritance hierarchy will need to be refactored/rebalanced, sort of like an unbalanced binary tree needs reshuffling from time to time in order to improve the average seek time. As I mentioned before, my co-workers are very smart; they just have been doing things a certain way and probably have an ability to hold a lot of unrelated crap in their head at once. I want to convince them to give composition and functional as opposed to OOP approach a try. To do that, I need to find some very good material. I do not think that a SCIP lecture or one by Rich Hickey will do - I am afraid it will be flagged down as too academic. Then, simple examples of Dog and Frog and AddressBook classes do not really connivence one way or the other - they show how inheritance can be converted to composition but not why it is truly and objectively better. What I am looking for is some real-world example of code that has been written with a lot of inheritance, then hit a wall and re-written in a different style that uses composition. Perhaps there is a blog or a chapter. I am looking for something that can summarize and illustrate the sort of pain that I am going through. I already have been throwing the phrase "composition over inheritance" around, but it was not received as enthusiastically as I had hoped. I do not want to be perceived as a new guy who likes to complain and bash existing code while looking for a perfect approach while not contributing fast enough. At the same time, my gut is convinced that inheritance is often the instrument of evil and I want to show a better way in a near future. Have you stumbled upon any great resources that can help me?

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  • Virtualhost one https site, the rest http

    - by RJP1
    I have a linode server with Apache2 running a handful of sites with virtualhosting. All sites work fine on port 80, but one site has a ssl certificate and also runs okay. My problem is as follows: The non-https sites, if visiting https://domain.com - show the contents of the only secure site... Is there a way of disabling the *:443 match for these non-secure sites? Thanks! EDIT (more information): Here's a typical config in sites-available for a normal insecure http site: <VirtualHost *:80> ServerName www.insecure.com ServerAlias insecure.com ... </VirtualHost> The secure https site is as follows: <VirtualHost *:80> ServerName www.secure.com Redirect permanent / https://secure.com/ </VirtualHost> <VirtualHost *:80> ServerName secure.com RedirectMatch permanent ^/(.*) https://secure.com/$1 </VirtualHost> <VirtualHost *:443> SSLEngine on SSLProtocol all SSLCertificateChainFile ... SSLCertificateFile ... SSLCertificateKeyFile ... SSLCACertificateFile ... ServerName secure.com ServerAlias secure.com ... </VirtualHost> So, visiting: http:/insecure.com - works http:/www.insecure.com - works http:/secure.com - redirects to https:/secure.com - works http:/www.secure.com - redirects to https:/secure.com - works https:/insecure.com - shows https:/secure.com - WRONG!

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  • Time Synch Architecture in Windows Domain Environment

    - by Param
    I just read the following article -- "In a domain, time synchronization takes place when Windows Time Service turns on during system startup and periodically while the system is running." ( http://technet.microsoft.com/en-us/library/cc779145%28v=ws.10%29.aspx ) From the above article i get to know that the first sync it take as soon as i start my system, but after that in how many minutes or second or in how many periodic interval my windows client ( Window XP, window7 or window server 2008 member ) synch with my Domain controller (PDC emulator )??? Do you have any idea, and how should i verify my synch time interval? My Domain Controller is Window server 2008 R2 Standard

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  • [Notepad++] delete rest of line after specific string

    - by nixdagibts
    I'm looking for a way to search for a specific string e.g. '=UUID:' and delete it and all following characters per line. I would prefer a way/macro/addon for notepad++. But all other tools or scripts are welcome :) Before ://81.88.22.6/=UUID:63969B2469B7A94EBBDBD7CB5B9C00BA ://-ad.cgi*=UUID:3C8EFF48B674CC42BF5B6E2B7BA820E7 ://-ads/*=UUID:0D6CF7D5BE3F034C8A136CC99A074406 Note that the numbers are always different per line so you couldn't do a search 'n replace with them. Should look like this after ://81.88.22.6/ ://-ad.cgi* ://-ads/*

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  • postfix: deliver mail to specific emai addresses locally and send the rest to relayhost

    - by sme
    I want to achieve the following with postfix: Almost all outgoing emails shall be sent via a relayhost, configured in main.cf with relayhost = my.mailserver There's one specific email address ([email protected]) for which I want the email to be delivered locally. I set up a local account on the machine to match the email address and added "mydomain.com" to the mydestination property in main.cf. Then of course postfix tries to deliver every email to @mydomain.com locally and bounces them because the respective user doesn't exist. Question http://serverfault.com/questions/149453/hybrid-gmail-mx-postfix-for-local-accounts seems to be somewhat related (though more complicated).

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  • Parse.com REST API in Java (NOT Android)

    - by Orange Peel
    I am trying to use the Parse.com REST API in Java. I have gone through the 4 solutions given here https://parse.com/docs/api_libraries and have selected Parse4J. After importing the source into Netbeans, along with importing the following libraries: org.slf4j:slf4j-api:jar:1.6.1 org.apache.httpcomponents:httpclient:jar:4.3.2 org.apache.httpcomponents:httpcore:jar:4.3.1 org.json:json:jar:20131018 commons-codec:commons-codec:jar:1.9 junit:junit:jar:4.11 ch.qos.logback:logback-classic:jar:0.9.28 ch.qos.logback:logback-core:jar:0.9.28 I ran the example code from https://github.com/thiagolocatelli/parse4j Parse.initialize(APP_ID, APP_REST_API_ID); // I replaced these with mine ParseObject gameScore = new ParseObject("GameScore"); gameScore.put("score", 1337); gameScore.put("playerName", "Sean Plott"); gameScore.put("cheatMode", false); gameScore.save(); And I got that it was missing org.apache.commons.logging, so I downloaded that and imported it. Then I ran the code again and got Exception in thread "main" java.lang.NoSuchMethodError: org.slf4j.spi.LocationAwareLogger.log(Lorg/slf4j/Marker;Ljava/lang/String;ILjava/lang/String;Ljava/lang/Throwable;)V at org.apache.commons.logging.impl.SLF4JLocationAwareLog.debug(SLF4JLocationAwareLog.java:120) at org.apache.http.client.protocol.RequestAddCookies.process(RequestAddCookies.java:122) at org.apache.http.protocol.ImmutableHttpProcessor.process(ImmutableHttpProcessor.java:131) at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:193) at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:85) at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:108) at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:186) at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:82) at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:106) at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:57) at org.parse4j.command.ParseCommand.perform(ParseCommand.java:44) at org.parse4j.ParseObject.save(ParseObject.java:450) I could probably fix this with another import, but I suppose then something else would pop up. I tried the other libraries with similar results, missing a bunch of libraries. Has anyone actually used REST API successfully in Java? If so, I would be grateful if you shared which library/s you used and anything else required to get it going successfully. I am using Netbeans. Thanks.

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  • Sharp architecture; Accessing Validation Results

    - by nabeelfarid
    I am exploring Sharp Architecture and I would like to know how to access the validation results after calling Entity.IsValid(). I have two scenarios e.g. 1) If the entity.IsValid() return false, I would like to add the errors to ModelState.AddModelError() collection in my controller. E.g. in the Northwind sample we have an EmployeesController.Create() action when we do employee.IsValid(), how can I get access to the errors? public ActionResult Create(Employee employee) { if (ViewData.ModelState.IsValid && employee.IsValid()) { employeeRepository.SaveOrUpdate(employee); } // .... } [I already know that when an Action method is called, modelbinder enforces validation rules(nhibernate validator attributes) as it parses incoming values and tries to assign them to the model object and if it can't parse the incoming values  then it register those as errors in modelstate for each model object property. But what if i have some custom validation. Thats why we do ModelState.IsValid first.] 2) In my test methods I would like to test the nhibernate validation rules as well. I can do entity.IsValid() but that only returns true/ false. I would like to Assert against the actual error not just true/ false. In my previous projects, I normally use a wrapper Service Layer for Repositories, and instead of calling Repositories method directly from controller, controllers call service layer methods which in turn call repository methods. In my Service Layer all my custom validation rules resides and Service Layer methods throws a custom exception with a NameValueCollection of errors which I can easily add to ModelState in my controller. This way I can also easily implement sophisticated business rules in my service layer as well. I kow sharp architecture also provides a Service Layer project. But what I am interested in and my next question is: How I can use NHibernate Vaidators to implement sophisticated custom business rules (not just null,empty, range etc.) and make Entity.IsValid() to verify those rules too ?

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  • Python libusb pyusb "mach-o, but wrong architecture"

    - by Jon
    I am having some trouble with the pyusb module. I have narrowed down the problem to a single line, and have created a small example script to replicate the error. #!/usr/bin/env python """ This module was created to isolate the problem in the pyusb package. Operating system: Mac OS 10.6.3 Python Version: 2.6.4 libusb 1.0.8 has been successfully installed using: sudo port install libusb I have also tried modifying /opt/local/etc/macports/macports.conf to force the i386 architecture instead of x86_64. """ from ctypes import * import ctypes.util libname = ctypes.util.find_library('usb-1.0') print 'libname: ', libname l = CDLL(libname, RTLD_GLOBAL) # RESULT: #libname: /usr/local/lib/libusb-1.0.dylib #Traceback (most recent call last): # File "./pyusb_problem.py", line 7, in <module> # l = CDLL(libname, RTLD_GLOBAL) # File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/ctypes/__init__.py", line 353, in __init__ # self._handle = _dlopen(self._name, mode) #OSError: dlopen(/usr/local/lib/libusb-1.0.dylib, 10): no suitable image found. Did find: # /usr/local/lib/libusb-1.0.dylib: mach-o, but wrong architecture # End of File This same script runs on Ubuntu 10.04 successfully. I have tried building the libusb module (directly from source AND through macports) for 32-bit (i386) instead of x86_64 (default for OS 10.6), but I receive the same error. Thank-you in advance for your help!

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  • Making REST request using LWP::Simple

    - by Alienfluid
    I am trying to use LWP::Simple to make a GET request to a REST service. Here's the simple code: use LWP::Simple; $uri = "http://api.stackoverflow.com/0.8/questions/tagged/php"; $jsonresponse= get $uri; print $jsonresponse; On my local machine, running Ubuntu 10.4, and Perl version 5.10.1: farhan@farhan-lnx:~$ perl --version This is perl, v5.10.1 (*) built for x86_64-linux-gnu-thread-multi I can get the correct response and have it printed on the screen. E.g.: farhan@farhan-lnx:~$ head -10 output.txt { "total": 1000, "page": 1, "pagesize": 30, "questions": [ { "tags": [ "php", "arrays", "coding-style" (... snipped ...) But on my host's machine to which I SSH into, I get garbage printed on the screen for the same exact code. I am assuming it has something to do with the encoding, but the REST service does not return the character set type in the response, so how do I force LWP::Simple to use the correct encoding? Any ideas what may be going on here? Here's the version of Perl on my host's machine: [dredd]$ perl --version This is perl, v5.8.8 built for x86_64-linux-gnu-thread-multi

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  • sharp architecture question

    - by csetzkorn
    I am trying to get my head around the sharp architecture and follow the tutorial. I am using this code: using Bla.Core; using System.Collections.Generic; using Bla.Core.DataInterfaces; using System.Web.Mvc; using SharpArch.Core; using SharpArch.Web; using Bla.Web; namespace Bla.Web.Controllers { public class UsersController { public UsersController(IUserRepository userRepository) { Check.Require(userRepository != null,"userRepository may not be null"); this.userRepository = userRepository; } public ActionResult ListStaffMembersMatching(string filter) { List<User> matchingUsers = userRepository.FindAllMatching(filter); return View("ListUsersMatchingFilter", matchingUsers); } private readonly IUserRepository userRepository; } } I get this error: The name 'View' does not exist in the current context I have used all the correct using statements and referenced the assemblies as far as I can see. The views live in Bla.Web in this architecture. Can anyone see the problem? Thanks. Christian

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  • Help Modifying Generic REST Helper PHP Example Code to Support XML DOM

    - by Jennifer Baker
    Hi! I found this example PHP source code at HTTP POST from PHP, without cURL I need some help modifying the example PHP source to support XML DOM for manipulating a REST API. I thought that if I update the CASE statement for the XML section below from $r = simplexml_load_string($res); to $r = new DOMDocument(); $r->load($res); that it would work but it doesn't. :( Any help would be appreciated. function rest_helper($url, $params = null, $verb = 'GET', $format = 'xml') { $cparams = array( 'http' => array( 'method' => $verb, 'ignore_errors' => true ) ); if ($params !== null) { $params = http_build_query($params); if ($verb == 'POST') { $cparams['http']['content'] = $params; } else { $url .= '?' . $params; } } $context = stream_context_create($cparams); $fp = fopen($url, 'rb', false, $context); if (!$fp) { $res = false; } else { // If you're trying to troubleshoot problems, try uncommenting the // next two lines; it will show you the HTTP response headers across // all the redirects: // $meta = stream_get_meta_data($fp); // var_dump($meta['wrapper_data']); $res = stream_get_contents($fp); } if ($res === false) { throw new Exception("$verb $url failed: $php_errormsg"); } switch ($format) { case 'json': $r = json_decode($res); if ($r === null) { throw new Exception("failed to decode $res as json"); } return $r; case 'xml': $r = simplexml_load_string($res); if ($r === null) { throw new Exception("failed to decode $res as xml"); } return $r; } return $res; }

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  • Creating a REST client API using Reactive Extensions (Rx)

    - by Jonas Follesø
    I'm trying to get my head around the right use cases for Reactive Extensions (Rx). The examples that keeps coming up are UI events (drag and drop, drawing), and suggestions that Rx is suitable for asynchronous applications/operations such as web service calls. I'm working on an application where I need to write a tiny client API for a REST service. I need to call four REST end-points, three to get some reference data (Airports, Airlines, and Statuses), and the fourth is the main service that will give you flight times for a given airport. I have created classes exposing the three reference data services, and the methods look something like this: public Observable<Airport> GetAirports() public Observable<Airline> GetAirlines() public Observable<Status> GetStatuses() public Observable<Flights> GetFlights(string airport) In my GetFlights method I want each Flight to hold a reference the Airport it's departing from, and the Airline operating the flight. To do that I need the data from GetAirports and GetAirlines to be available. My initial thinking was something like this: Write a Rx Query that will Subscribe on the three reference services (Airports, Airlines and Statuses) Add results into a Dictionary (airline code and Airline object) When all three GetAirports, GetAirlines and GetStatuses are complete, then return the GetFlights IObservable. Is this a reasonable scenario for Rx? I'm developing on the Windows Phone 7, so I'm not sure if there are major differences in the Rx implementations across the different platforms.

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  • Web application architecture, and application servers?

    - by seanieb
    Hi, I'm building a web application, and I need to use an architecture that allows me to run it on two servers. The application scrapes information from other sites periodically, and on input from the end user. To do this I'm using Php+curl to scrape the information, Php or python to parse it and store the results in a MySQLDB. Then I will use Python to run some algorithms on the data, this will happen both periodically and on input from the end user. I'm going to cache some of the results in the MySQL DB and sometimes if it is specific to the user, skip storing the data and serve it to the user. I'm think of using Php for the website front end on a separate web server, running the Php spider, MySQL DB and python on another server. As you can see I'm fairly clueless. I'm familiar with using Php, MySQL and the basics of Python, but bringing this all together using something more complex than a cron job is new to me. How do go about implementing this? What frame work(s) should I use? Is MVC a good architecture for this? (I'm new to MVC, architectures etc.) Is Cakephp a good solution? If so will I be able to control and monitor the Python code using it?

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  • Android - Basic CRUD (REST/RPC client) to remote server

    - by bsreekanth
    There are lot of discussion about REST client implementation in android, based on the talk at GoogleIO 2010, by Virgil Dobjanschi. My requirement may not necessarily involved, as I have some freedom to choose the configuration. I only target tablets configuration changes can be prevented if no other easy way (fix at Landscape mode etc) I am trying to achieve. Basic CRUD operation to my server (JSON RPC/ REST). Basically mimic an ajax request from android app (no webview, need native app) Based on the above mentioned talk, and some reading I see these options. Implement any of the 3 mentioned in the Google IO talk Especially, the last pattern may be more suitable as I don't care much of caching. But not sure how "real time" is sync implementation. Use HTTP request in AsyncTask. Simplest, but need to avoid re-sending request during change in device configuration (orientation change etc). Even if I fix at one orientation, recreation of activity still happens. So need to handle it elegantly. Use service to handle http request. So far, it say use service for long ruiing request. Not sure whether it is a good approach for simple GET/POST/PUt requests. Please share your experience on what could be the best way.

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  • make arm architecture c library in mac

    - by gamegamelife
    I'm trying to make my own c library in Mac and include it to my iphone program. The c code is simple , like this: math.h: int myPow2(int); math.c: #include "math.h" int myPow2(int num) { return num*num; } I search how to make the c library file ( .a or .lib ..etc) seems need to use gcc compiler (Is there other methods?) so I use this command: gcc -c math.c -o math.o ar rcs libmath.a math.o And include it in iPhone Project. Now it has the problem when build xcode iphone project. "file was built for unsupported file format which is not the architecture being linked" I found some pages discuss about the problem, but no detail how to make the i386/arm architecture library. And I finally use this command to do it: gcc -arch i386 -c math.c -o math.o /Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/arm-apple-darwin10-gcc-4.2.1 -c math.c -o math.o I dont know if this method is correct? Or there has another method to do it?

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  • Declarative Architectures in Infrastructure as a Service (IaaS)

    - by BuckWoody
    I deal with computing architectures by first laying out requirements, and then laying in any constraints for it's success. Only then do I bring in computing elements to apply to the system. As an example, a requirement might be "world-side availability" and a constraint might be "with less than 80ms response time and full HA" or something similar. Then I can choose from the best fit of technologies which range from full-up on-premises computing to IaaS, PaaS or SaaS. I also deal in abstraction layers - on-premises systems are fully under your control, in IaaS the hardware is abstracted (but not the OS, scale, runtimes and so on), in PaaS the hardware and the OS is abstracted and you focus on code and data only, and in SaaS everything is abstracted - you merely purchase the function you want (like an e-mail server or some such) and simply use it. When you think about solutions this way, the architecture moves to the primary factor in your decision. It's problem-first architecting, and then laying in whatever technology or vendor best fixes the problem. To that end, most architects design a solution using a graphical tool (I use Visio) and then creating documents that  let the rest of the team (and business) know what is required. It's the template, or recipe, for the solution. This is extremely easy to do for SaaS - you merely point out what the needs are, research the vendor and present the findings (and bill) to the business. IT might not even be involved there. In PaaS it's not much more complicated - you use the same Application Lifecycle Management and design tools you always have for code, such as Visual Studio or some other process and toolset, and you can "stamp out" the application in multiple locations, update it and so on. IaaS is another story. Here you have multiple machines, operating systems, patches, virus scanning, run-times, scale-patterns and tools and much more that you have to deal with, since essentially it's just an in-house system being hosted by someone else. You can certainly automate builds of servers - we do this as technical professionals every day. From Windows to Linux, it's simple enough to create a "build script" that makes a system just like the one we made yesterday. What is more problematic is being able to tie those systems together in a coherent way (as a solution) and then stamp that out repeatedly, especially when you might want to deploy that solution on-premises, or in one cloud vendor or another. Lately I've been working with a company called RightScale that does exactly this. I'll point you to their site for more info, but the general idea is that you document out your intent for a set of servers, and it will deploy them to on-premises clouds, Windows Azure, and other cloud providers all from the same script. In other words, it doesn't contain the images or anything like that - it contains the scripts to build them on-premises or on a cloud vendor like Microsoft. Using a tool like this, you combine the steps of designing a system (all the way down to passwords and accounts if you wish) and then the document drives the distribution and implementation of that intent. As time goes on and more and more companies implement solutions on various providers (perhaps for HA and DR) then this becomes a compelling investigation. The RightScale information is here, if you want to investigate it further. Yes, there are other methods I've found, but most are tied to a single kind of cloud, and I'm not into vendor lock-in. Poppa Bear Level - Hands-on EvaluateRightScale at no cost.  Just bring your Windows Azurecredentials and follow the these tutorials: Sign Up for Windows Azure Add     Windows Azure to a RightScale Account Windows Azure Virtual Machines     3-tier Deployment Momma Bear Level - Just the Right level... ;0)  WindowsAzure Evaluation Guide - if you are new toWindows Azure Virtual Machines and new to RightScale, we recommend that youread the entire evaluation guide to gain a more complete understanding of theWindows Azure + RightScale solution.    WindowsAzure Support Page @ support.rightscale.com - FAQ's, tutorials,etc. for  Windows Azure Virtual Machines (Work in Progress) Baby Bear Level - Marketing WindowsAzure Page @ www.rightscale.com - find overview informationincluding solution briefs and presentation & demonstration videos   Scale     and Automate Applications on Windows Azure  Solution Brief     - how RightScale makes Windows Azure Virtual Machine even better SQL     Server on Windows Azure  Solution Brief   -       Run Highly Available SQL Server on Windows Azure Virtual Machines

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  • High Availability for IaaS, PaaS and SaaS in the Cloud

    - by BuckWoody
    Outages, natural disasters and unforeseen events have proved that even in a distributed architecture, you need to plan for High Availability (HA). In this entry I'll explain a few considerations for HA within Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS) and Software-as-a-Service (SaaS). In a separate post I'll talk more about Disaster Recovery (DR), since each paradigm has a different way to handle that. Planning for HA in IaaS IaaS involves Virtual Machines - so in effect, an HA strategy here takes on many of the same characteristics as it would on-premises. The primary difference is that the vendor controls the hardware, so you need to verify what they do for things like local redundancy and so on from the hardware perspective. As far as what you can control and plan for, the primary factors fall into three areas: multiple instances, geographical dispersion and task-switching. In almost every cloud vendor I've studied, to ensure your application will be protected by any level of HA, you need to have at least two of the Instances (VM's) running. This makes sense, but you might assume that the vendor just takes care of that for you - they don't. If a single VM goes down (for whatever reason) then the access to it is lost. Depending on multiple factors, you might be able to recover the data, but you should assume that you can't. You should keep a sync to another location (perhaps the vendor's storage system in another geographic datacenter or to a local location) to ensure you can continue to serve your clients. You'll also need to host the same VM's in another geographical location. Everything from a vendor outage to a network path problem could prevent your users from reaching the system, so you need to have multiple locations to handle this. This means that you'll have to figure out how to manage state between the geo's. If the system goes down in the middle of a transaction, you need to figure out what part of the process the system was in, and then re-create or transfer that state to the second set of systems. If you didn't write the software yourself, this is non-trivial. You'll also need a manual or automatic process to detect the failure and re-route the traffic to your secondary location. You could flip a DNS entry (if your application can tolerate that) or invoke another process to alias the first system to the second, such as load-balancing and so on. There are many options, but all of them involve coding the state into the application layer. If you've simply moved a state-ful application to VM's, you may not be able to easily implement an HA solution. Planning for HA in PaaS Implementing HA in PaaS is a bit simpler, since it's built on the concept of stateless applications deployment. Once again, you need at least two copies of each element in the solution (web roles, worker roles, etc.) to remain available in a single datacenter. Also, you need to deploy the application again in a separate geo, but the advantage here is that you could work out a "shared storage" model such that state is auto-balanced across the world. In fact, you don't have to maintain a "DR" site, the alternate location can be live and serving clients, and only take on extra load if the other site is not available. In Windows Azure, you can use the Traffic Manager service top route the requests as a type of auto balancer. Even with these benefits, I recommend a second backup of storage in another geographic location. Storage is inexpensive; and that second copy can be used for not only HA but DR. Planning for HA in SaaS In Software-as-a-Service (such as Office 365, or Hadoop in Windows Azure) You have far less control over the HA solution, although you still maintain the responsibility to ensure you have it. Since each SaaS is different, check with the vendor on the solution for HA - and make sure you understand what they do and what you are responsible for. They may have no HA for that solution, or pin it to a particular geo, or perhaps they have a massive HA built in with automatic load balancing (which is often the case).   All of these options (with the exception of SaaS) involve higher costs for the design. Do not sacrifice reliability for cost - that will always cost you more in the end. Build in the redundancy and HA at the very outset of the project - if you try to tack it on later in the process the business will push back and potentially not implement HA. References: http://www.bing.com/search?q=windows+azure+High+Availability  (each type of implementation is different, so I'm routing you to a search on the topic - look for the "Patterns and Practices" results for the area in Azure you're interested in)

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  • SOA, Governance, and Drugs

    Why is IT governance important in service oriented architecture (SOA)? IT Governance provides a framework for making appropriate decisions based on company guidelines and accepted standards. This framework also outlines each stakeholder’s responsibilities and authority when making important architectural or design decisions. Furthermore, this framework of governance defines parameters and constraints that are used to give context and perspective when making decisions. The use of governance as it applies to SOA ensures that specific design principles and patterns are used when developing and maintaining services. When governance is consistently applied systems the following benefits are achieved according to Anne Thomas Manes in 2010. Governance makes sure that services conform to standard interface patterns, common data modeling practices, and promotes the incorporation of existing system functionality by building on top of other available services across a system. Governance defines development standards based on proven design principles and patterns that promote reuse and composition. Governance provides developers a set of proven design principles, standards and practices that promote the reduction in system based component dependencies.  By following these guidelines, individual components will be easier to maintain. For me personally, I am a fan of IT governance, and feel that it valuable part of any corporate IT department. However, depending on how it is implemented can really affect the value of using IT governance.  Companies need to find a way to ensure that governance does not become extreme in its policies and procedures. I know for me personally, I would really dislike working under a completely totalitarian or laissez-faire version of governance. Developers need to be able to be creative in their designs and too much governance can really impede the design process and prevent the most optimal design from being developed. On the other hand, with no governance enforced, no standards will be followed and accepted design patterns will be ignored. I have personally had to spend a lot of time working on this particular scenario and I have found that the concept of code reuse and composition is almost nonexistent.  Based on this, too much time and money is wasted on redeveloping existing aspects of an application that already exist within the system as a whole. I think moving forward we will see a staggered form of IT governance, regardless if it is for SOA or IT in general.  Depending on the size of a company and the size of its IT department,  I can see IT governance as a layered approach in that the top layer will be defined by enterprise architects that focus on abstract concepts pertaining to high level design, general  guidelines, acceptable best practices, and recommended design patterns.  The next layer will be defined by solution architects or department managers that further expand on abstracted guidelines defined by the enterprise architects. This layer will contain further definitions as to when various design patterns, coding standards, and best practices are to be applied based on the context of the solutions that are being developed by the department. The final layer will be defined by the system designer or a solutions architect assed to a project in that they will define what design patterns will be used in a solution, naming conventions, as well as outline how a system will function based on the best practices defined by the previous layers. This layered approach allows for IT departments to be flexible in that system designers have creative leeway in designing solutions to meet the needs of the business, but they must operate within the confines of the abstracted IT governance guidelines.  A real world example of this can be seen in the United States as it pertains to governance of the people in that the US government defines rules and regulations in the abstract and then the state governments take these guidelines and applies them based on the will of the people in each individual state. Furthermore, the county or city governments are the ones that actually enforce these rules based on how they are interpreted by local community.  To further define my example, the United States government defines that marijuana is illegal. Each individual state has the option to determine this regulation as it wishes in that the state of Florida determines that all uses of the drug are illegal, but the state of California legally allows the use of marijuana for medicinal purposes only. Based on these accepted practices each local government enforces these rules in that a police officer will arrest anyone in the state of Florida for having this drug on them if they walk down the street, but in California if a person has a medical prescription for the drug they will not get arrested.  REFERENCESThomas Manes, Anne. (2010). Understanding SOA Governance: http://www.soamag.com/I40/0610-2.php

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  • Windows Service Hosting WCF Objects over SSL (https) - Custom JSON Error Handling Doesn't Work

    - by bpatrick100
    I will first show the code that works in a non-ssl (http) environment. This code uses a custom json error handler, and all errors thrown, do get bubbled up to the client javascript (ajax). // Create webservice endpoint WebHttpBinding binding = new WebHttpBinding(); ServiceEndpoint serviceEndPoint = new ServiceEndpoint(ContractDescription.GetContract(Type.GetType(svcHost.serviceContract + ", " + svcHost.assemblyName)), binding, new EndpointAddress(svcHost.hostUrl)); // Add exception handler serviceEndPoint.Behaviors.Add(new FaultingWebHttpBehavior()); // Create host and add webservice endpoint WebServiceHost webServiceHost = new WebServiceHost(svcHost.obj, new Uri(svcHost.hostUrl)); webServiceHost.Description.Endpoints.Add(serviceEndPoint); webServiceHost.Open(); I'll also show you what the FaultingWebHttpBehavior class looks like: public class FaultingWebHttpBehavior : WebHttpBehavior { public FaultingWebHttpBehavior() { } protected override void AddServerErrorHandlers(ServiceEndpoint endpoint, EndpointDispatcher endpointDispatcher) { endpointDispatcher.ChannelDispatcher.ErrorHandlers.Clear(); endpointDispatcher.ChannelDispatcher.ErrorHandlers.Add(new ErrorHandler()); } public class ErrorHandler : IErrorHandler { public bool HandleError(Exception error) { return true; } public void ProvideFault(Exception error, MessageVersion version, ref Message fault) { // Build an object to return a json serialized exception GeneralFault generalFault = new GeneralFault(); generalFault.BaseType = "Exception"; generalFault.Type = error.GetType().ToString(); generalFault.Message = error.Message; // Create the fault object to return to the client fault = Message.CreateMessage(version, "", generalFault, new DataContractJsonSerializer(typeof(GeneralFault))); WebBodyFormatMessageProperty wbf = new WebBodyFormatMessageProperty(WebContentFormat.Json); fault.Properties.Add(WebBodyFormatMessageProperty.Name, wbf); } } } [DataContract] public class GeneralFault { [DataMember] public string BaseType; [DataMember] public string Type; [DataMember] public string Message; } The AddServerErrorHandlers() method gets called automatically, once webServiceHost.Open() gets called. This sets up the custom json error handler, and life is good :-) The problem comes, when we switch to and SSL (https) environment. I'll now show you endpoint creation code for SSL: // Create webservice endpoint WebHttpBinding binding = new WebHttpBinding(); ServiceEndpoint serviceEndPoint = new ServiceEndpoint(ContractDescription.GetContract(Type.GetType(svcHost.serviceContract + ", " + svcHost.assemblyName)), binding, new EndpointAddress(svcHost.hostUrl)); // This exception handler code below (FaultingWebHttpBehavior) doesn't work with SSL communication for some reason, need to resarch... // Add exception handler serviceEndPoint.Behaviors.Add(new FaultingWebHttpBehavior()); //Add Https Endpoint WebServiceHost webServiceHost = new WebServiceHost(svcHost.obj, new Uri(svcHost.hostUrl)); binding.Security.Mode = WebHttpSecurityMode.Transport; binding.Security.Transport.ClientCredentialType = HttpClientCredentialType.None; webServiceHost.AddServiceEndpoint(svcHost.serviceContract, binding, string.Empty); Now, with this SSL endpoint code, the service starts up correctly, and wcf hosted objects can be communicated with just fine via client javascript. However, the custom error handler doesn't work. The reason is, the AddServerErrorHandlers() method never gets called when webServiceHost.Open() is run. So, can anyone tell me what is wrong with this picture? And why, is AddServerErrorHandlers() not getting called automatically, like it does when I'm using non-ssl endpoints? Thanks!

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  • Jquery data retrival returns null with json data

    - by user545520
    Hello Everyone, I have below sample json file: {"jsonData":{"REC":[{"TEST":"T","TEST1":"T1","TEST2":"T2"},{"R":"R","R1":"R1","R3":"R3"}], "DATA":{"FIRST":0,"SEC":1}}}. I want to retrieve data from json file,i am try like below,but it is giving null. from result object:i am retrieving data like below: to retrive the value T: this.jsonData.REC.TEST To retrieve the value R1: this.jsonData.DATA.FIRST Please correct me if i am doing any wrong. Thanks in Advance.

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