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• Handling incremental Data Modeling Changes in Functional Programming

  - by Adam Gent

  Most of the problems I have to solve in my job as a developer have to do with data modeling. For example in a OOP Web Application world I often have to change the data properties that are in a object to meet new requirements. If I'm lucky I don't even need to programmatically add new "behavior" code (functions,methods). Instead I can declarative add validation and even UI options by annotating the property (Java). In Functional Programming it seems that adding new data properties requires lots of code changes because of pattern matching and data constructors (Haskell, ML). How do I minimize this problem? This seems to be a recognized problem as Xavier Leroy states nicely on page 24 of "Objects and Classes vs. Modules" - To summarize for those that don't have a PostScript viewer it basically says FP languages are better than OOP languages for adding new behavior over data objects but OOP languages are better for adding new data objects/properties. Are there any design pattern used in FP languages to help mitigate this problem? I have read Phillip Wadler's recommendation of using Monads to help this modularity problem but I'm not sure I understand how?

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• Best emailing approach with template emails

  - by Harun Baris Bulut

  Hi all, We are creating a project with lots of different mail templates in it. There are different messages for different purposes and we are trying to make the coding easy and understandable for the future. By the way we have different transport classes like e-mail, sms, twitter vs... Now we are doing this but I dont know if there is a better solution. We have a class called H2B_Message_Container_Mail_About_Blablabla it has 4 methods; interface H2B_Message_Mail_Interface { public function setName($name); public function setValue($key, $value); public function getMailBody(); public function getMailSubject(); } and in the mail body there are various variables as expected. before we send the mail, we get the variable values from the database with JSON format and decode it. Then we send it like; $mail = new H2B_Message_Mail(); $mail->setTemplate($newTemplate); $mail->send(); The question is; is there a better way to do this ?

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• Implementing parts of rfc4226 (HOTP) in mysql

  - by Moose Morals

  Like the title says, I'm trying to implement the programmatic parts of RFC4226 "HOTP: An HMAC-Based One-Time Password Algorithm" in SQL. I think I've got a version that works (in that for a small test sample, it produces the same result as the Java version in the code), but it contains a nested pair of hex(unhex()) calls, which I feel can be done better. I am constrained by a) needing to do this algorithm, and b) needing to do it in mysql, otherwise I'm happy to look at other ways of doing this. What I've got so far: -- From the inside out... -- Concatinate the users secret, and the number of time its been used -- find the SHA1 hash of that string -- Turn a 40 byte hex encoding into a 20 byte binary string -- keep the first 4 bytes -- turn those back into a hex represnetation -- convert that into an integer -- Throw away the most-significant bit (solves signed/unsigned problems) -- Truncate to 6 digits -- store into otp -- from the otpsecrets table select (conv(hex(substr(unhex(sha1(concat(secret, uses))), 1, 4)), 16, 10) & 0x7fffffff) % 1000000 into otp from otpsecrets; Is there a better (more efficient) way of doing this?

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• How to map different UI views in a RESTful web application?

  - by MicE

  Hello, I'm designing a web application, which will support both standard UIs (accessed via browsers) and a RESTful API (an XML/JSON-based web service). User agents will be able to differentiate between these by using different values in the Accept HTTP header. The RESTful API will use the following URI structure (example for an "article" resource): GET /article/ - gets a list of articles POST /article/ - adds a new article PUT /article/{id} - updates an existing article based on {id} DELETE /article/{id} - deletes an existing article based on {id} The UI part of the application will however need to support multiple views, for example: a standard resource view a view for submitting a new resource a view for editing an existing resource a view for deleting an existing resource (i.e. display delete confirmation) Note that the latter three views are still accessed via GET, even though they are processed via overloaded POST. Possible solution: Introduce additional parameters (keywords) into URIs which would identify individual views - i.e. on top of the above, the application would support the following URIs (but only for Content-Type: text/html): GET /article/add - displays a form for adding a new article (fetched via GET, processed via POST) GET /article/123 - displays article 123 in "view" mode (fetched via GET) GET /article/123/edit - displays article 123 in "edit" mode (fetched via GET, processed via PUT overloaded as POST) GET /article/123/delete - displays "delete" confirmation for article 123 (fetched via GET, processed via DELETE overloaded as POST) A better implementation of the above might be to put the add/edit/delete keywords into a GET parameter - since they do not change the resource we're working with, it might be better to keep the base URI same for all of them. My question is: How would you map the above URI structure to UIs served to the regular user, considering that there can be several views per each resource, please? Do you agree with the possible solution detailed above, or would you recommend a different approach based on your experience? NB: we've already implemented an application which consists of a standalone RESTful API and a standalone web application. I'm currently looking into options for future projects where these two would be merged together (i.e. in order to reduce overhead). Thank you, M.

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• Efficient data importing?

  - by Kevin

  We work with a lot of real estate, and while rearchitecting how the data is imported, I came across an interesting issue. Firstly, the way our system works (loosely speaking) is we run a Coldfusion process once a day that retrieves data provided from an IDX vendor via FTP. They push the data to us. Whatever they send us is what we get. Over the years, this has proven to be rather unstable. I am rearchitecting it with PHP on the RETS standard, which uses SOAP methods of retrieving data, which is already proven to be much better than what we had. When it comes to 'updating' existing data, my initial thought was to query only for data that was updated. There is a field for 'Modified' that tells you when a listing was last updated, and the code I have will grab any listing updated within the last 6 hours (give myself a window in case something goes wrong). However, I see a lot of real estate developers suggest creating 'batch' processes that run through all listings regardless of updated status that is constantly running. Is this the better way to do it? Or am I fine with just grabbing the data I know I need? It doesn't make a lot of sense to me to do more processing than necessary. Thoughts?

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• Home server hard drive: 186k start-stop cycles in 325 days?

  - by j-g-faustus

  I set up a home server about a year ago, using Ubuntu server (10.04 LTS at the moment), four disks in RAID 5 for storage (WD Green 1.5 TB) and a laptop drive for the OS. Today the output of smartctl, a command line utility for checking the SMART attributes of a hard drive, tells me that the primary OS drive has had no less than 186,000 start-stop cycles in 325 days and may be nearing the end of its lifespan. The smartctl output is in "normalized values", in this case a number between 200 and 000, where 200 is "brand new" and 000 means "worn out". My disk gets 001. So I wonder what happened: 186k start/stop cycles in 7820 hours is about one start/stop per 2.5 minutes around the clock. This seems somewhat excessive for a computer that sees actual use once or twice per day. (The RAID disks are normal, averaging to one start/stop per day, as expected.) Does anyone have similar experiences, or pointers to what might be the issue here? Specifically I'd like to know Why the massive start/stop count? Do I have some sort of configuration issue? Could there be a background service that is causing trouble? Could having a laptop disk as the OS drive be part of the problem? Can anyone confirm or deny this? Here is the /etc/hdparm.conf configuration /dev/sda { apm = 127 spindown_time = 120 } and the most relevant parts of smartctl --attributes /dev/sda: smartctl version 5.38 [x86_64-unknown-linux-gnu] Copyright (C) 2002-8 Bruce Allen === START OF READ SMART DATA SECTION === SMART Attributes Data Structure revision number: 16 Vendor Specific SMART Attributes with Thresholds: ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 1 Raw_Read_Error_Rate 0x002f 200 200 051 Pre-fail Always - 0 4 Start_Stop_Count 0x0032 001 001 000 Old_age Always - 185875 9 Power_On_Hours 0x0032 090 090 000 Old_age Always - 7820 12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 109 193 Load_Cycle_Count 0x0032 118 118 000 Old_age Always - 246833 194 Temperature_Celsius 0x0022 107 098 000 Old_age Always - 36 As I generally prefer my drives to last more than a year, any advice is appreciated.

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• CUDA: When to use shared memory and when to rely on L1 caching?

  - by Roger Dahl

  After Compute Capability 2.0 (Fermi) was released, I've wondered if there are any use cases left for shared memory. That is, when is it better to use shared memory than just let L1 perform its magic in the background? Is shared memory simply there to let algorithms designed for CC < 2.0 run efficiently without modifications? To collaborate via shared memory, threads in a block write to shared memory and synchronize with __syncthreads(). Why not simply write to global memory (through L1), and synchronize with __threadfence_block()? The latter option should be easier to implement since it doesn't have to relate to two different locations of values, and it should be faster because there is no explicit copying from global to shared memory. Since the data gets cached in L1, threads don't have to wait for data to actually make it all the way out to global memory. With shared memory, one is guaranteed that a value that was put there remains there throughout the duration of the block. This is as opposed to values in L1, which get evicted if they are not used often enough. Are there any cases where it's better too cache such rarely used data in shared memory than to let the L1 manage them based on the usage pattern that the algorithm actually has?

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• How to fix display on external Samsung Syncmaster shifted to the right when connected to Macbook Pro?

  - by joe larson

  Is there something special I need to do to be able to use external LCD displays with my new MacBook Pro? Do I need extra software, or do I possibly need a different cable? I'm attempting to use an external display with my MBP. I've got a "Mini DisplayPort to VGA Female Adapter for Mac", plugged into the thunderbolt port on my MBP, which I understood should be compatible with thunderbolt. I've tried this with three different SyncMaster models: a B2330 (21.5"), a EX2220 (22"), and a third (also 22" ish) which I don't have the model # for -- but all are 1920x1080 resolution; plus an additional HP monitor of similar size and resolution. In all four cases, the MBP recognizes the screen and choses the correct resolution. However, the display is shifted over about 1 inch. This is true no matter if I change screen resolutions also. The controls on the monitor for horizontal position don't help. Also, sometimes (especially if I drag an app over into the second screen), the screen starts skipping left to right and having bands of fuzz. Additionally, the monitor will periodically blink off for a moment, trying to switch from Digital to Analog and back (the Syncmaster shows text on the screen to tell you it's trying to do this). Often when it comes back from one of these blank-outs, it will show OK (no skipping or fuzz) but still shifted right; then after a few seconds it will go wrong again skipping and fuzzy. This photo shows the worst of it. I've added red rectangles to show the physical edge of the screen, and a yellow rectangle to show the empty space on the left of the screen. (Sorry for the awful quality and lighting!) Also, it's worth noting I am on Mac OS X 10.6.7, and yes I have this update 1.4 installed.

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• MVC design question for forms

  - by kenny99

  Hi, I'm developing an app which has a large amount of related form data to be handled. I'm using a MVC structure and all of the related data is represented in my models, along with the handling of data validation from form submissions. I'm looking for some advice on a good way to approach laying out my controllers - basically I will have a huge form which will be broken down into manageable categories (similar to a credit card app) where the user progresses through each stage/category filling out the answers. All of these form categories are related to the main relation/object, but not to each other. Does it make more sense to have each subform/category as a method in the main controller class (which will make that one controller fairly massive), or would it be better to break each category into a subclass of the main controller? It may be just for neatness that the second approach is better, but I'm struggling to see much of a difference between either creating a new method for each category (which communicates with the model and outputs errors/success) or creating a new controller to handle the same functionality. Thanks in advance for any guidance!

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• Autologin for web application

  - by Maulin

  We want to AutoLogin feature to allow user directly login using link into our Web Application. What is the best way achieve this? We have following approches in our mind. 1) Store user credentials(username/password) in cookie. Send cookie for authentication. e.g. http: //www.mysite.com/AutoLogin (here username/password will be passed in cookie) OR Pass user credentials in link URL. http: //www.mysite.com/AutoLogin?userid=<&password=< 2) Generate randon token and store user random token and user IP on server side database. When user login using link, validate token and user IP on server. e.g. http: //www.mysite.com/AutoLogin?token=< The problem with 1st approach is if hacker copies link/cookie from user machine to another machine he can login. The problem with 2nd approach is the user ip will be same for all users of same organization behind proxy. Which one is better from above from security perspective? If there is better solution which is other than mentioned above, please let us know.

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• Using Active Directory to authenticate users in a WWW facing website

  - by Basiclife

  Hi, I'm looking at starting a new web app which needs to be secure (if for no other reason than that we'll need PCI accreditation at some point). From previous experience working with PCI (on a domain), the preferred method is to use integrated windows authentication which is then passed all the way through the app to the database. This allows for better auditing as well as object-level permissions (ie an end user can't read the credit card table). There are advantages in that even if someone compromises the webserver, they won't be able to glean any additional information from the database. Also, the webserver isn't storing any database credentials (beyond perhaps a simple anonymous user with very few permissions) So, now I'm looking at the new web app which will be on the public internet. One suggestion is to have a Active Directory server and create windows accounts on the AD for each user of the site. These users will then be placed into the appropriate NT groups to decide which DB permissions they should have (and which pages they can access). ASP already provides the AD membership provider and role provider so this should be fairly simple to implement. There are a number of questions around this - Scalability, reliability, etc... and I was wondering if there is anyone out there with experience of this approach or, even better, some good reasons why to do it / not to do it. Any input appreciated Regards Basiclife

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• Why is MySQL with InnoDB doing a table scan when key exists and choosing to examine 70 times more ro

  - by andysk

  Hello, I'm troubleshooting a query performance problem. Here's an expected query plan from explain: mysql> explain select * from table1 where tdcol between '2010-04-13:00:00' and '2010-04-14 03:16'; +----+-------------+--------------------+-------+---------------+--------------+---------+------+---------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+--------------------+-------+---------------+--------------+---------+------+---------+-------------+ | 1 | SIMPLE | table1 | range | tdcol | tdcol | 8 | NULL | 5437848 | Using where | +----+-------------+--------------------+-------+---------------+--------------+---------+------+---------+-------------+ 1 row in set (0.00 sec) That makes sense, since the index named tdcol (KEY tdcol (tdcol)) is used, and about 5M rows should be selected from this query. However, if I query for just one more minute of data, we get this query plan: mysql> explain select * from table1 where tdcol between '2010-04-13 00:00' and '2010-04-14 03:17'; +----+-------------+--------------------+------+---------------+------+---------+------+-----------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+--------------------+------+---------------+------+---------+------+-----------+-------------+ | 1 | SIMPLE | table1 | ALL | tdcol | NULL | NULL | NULL | 381601300 | Using where | +----+-------------+--------------------+------+---------------+------+---------+------+-----------+-------------+ 1 row in set (0.00 sec) The optimizer believes that the scan will be better, but it's over 70x more rows to examine, so I have a hard time believing that the table scan is better. Also, the 'USE KEY tdcol' syntax does not change the query plan. Thanks in advance for any help, and I'm more than happy to provide more info/answer questions.

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• Saving twice don't update my object in JDO

  - by Javi

  Hello I have an object persisted in the GAE datastore using JDO. The object looks like this: public class MyObject implements Serializable, StoreCallback { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) @Extension(vendorName="datanucleus", key="gae.encoded-pk", value="true") private String id; @Persistent private String firstId; ... } As usually when the object is stored for the first time a new id value is generated for the identifier. I need that if I don't provide a value for firstId it sets the same value as the id. I don't want to solve it with a special getter which checks for null value in firstId and then return the id value because I want to make queries relating on firstId. I can do it in this way by saving the object twice (Probably there's a better way to do this, but I'll do it in this way until I find a better one). But it is not working. when I debug it I can see that result.firstId is set with the id value and it seems to be persisted, but when I go into the datastore I see that firstId is null (as it was saved the first time). This save method is in my DAO and it is called in another save method in the service annotated with @Transactional. Does anyone have any idea why the second object in not persisted properly? @Override public MyObject save(MyObject obj) { PersistenceManager pm = JDOHelper.getPersistenceManagerFactory("transactions-optional"); MyObject result = pm.makePersistent(obj); if(result.getFirstId() == null){ result.setFirstId(result.getId()); result = pm.makePersistent(result); } return result; } Thanks.

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• Advantages/disadvantages of Python and Ruby

  - by Seburdis

  I know this is going to seem a little like all the other python vs ruby question out there, but I'm not looking specifically to pick one over the other all the time. My question is, essentially, why would you use one language over the other when you are starting a new project? What features does ruby have that python doesn't that would make you decide on it for a given project? What about python over ruby? I was just recently thinking about the differentiation between the two languages because of Jamis Buck's "There is no magic, only awesome" series of articles (4 parts, available here) when I realized I really don't know enough about the two languages to know when to choose one over the other. I'm hoping to get objective answers from people who have experience with both languages, rather than just "python is better, ruby sucks" kind of responses. If you know of a feature in one language that doesn't exist in the other and is great in a certain situation, feel free to chime in and say why you think it's awesome. If you have another language comparable to these that you'd like to suggest pros/cons for, like groovy for example, that would be appreciated too. Some thing I know each language has going for it: Ruby: Awesome metaprogramming Great community Wide selection of Gems Rails Great code readability, usually MacRuby is great for native development on Mac without objc Amazing testing tools (cucumber, rspec, shoulda, autotest, etc.) Python: Whitespace indentation List comprehensions Better functional programming support? Lots of support on linux Easy_install isn't far from gems Great variety of libraries available

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• JScrollPanel without scrollbars

  - by Erik Itland

  I'm trying to use a JScrollPanel to display a JPanel that might be too big for the containing Jpanel. I don't want to show the scrollbars (yes, this is questionable UI design, but it is my best guess of what the customer wants. We use the same idea other places in the application, and I feel this case have given me enough time to ponder if I can do it in a better way, but if you have a better idea I might accept it an answer.) First attempt: set verticalScrollBarPolicy to NEVER. Result: Scrolling using mouse wheel doesn't work. Second attempt: set the scrollbars to null. Result: Scrolling using mouse wheel doesn't work. Third attempt: set scrollbars visible property to false. Result: It is immidiately set visible by Swing. Fourth attempt: inject a scrollbar where setVisible is overridden to do nothing when called with true. Result: Can't remember exactly, but I think it just didn't work. Fifth attempt: inject a scrollbar where setBounds are overridden. Result: Just didn't look nice. (I might have missed something here, though.) Sixth attempt: ask stackoverflow. Result: Pending. Scrolling works once scrollbars are back.

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• Elegantly handling constraint violations in EJB/JPA environment?

  - by hallidave

  I'm working with EJB and JPA on a Glassfish v3 app server. I have an Entity class where I'm forcing one of the fields to be unique with a @Column annotation. @Entity public class MyEntity implements Serializable { private String uniqueName; public MyEntity() { } @Column(unique = true, nullable = false) public String getUniqueName() { return uniqueName; } public void setUniqueName(String uniqueName) { this.uniqueName = uniqueName; } } When I try to persist an object with this field set to a non-unique value I get an exception (as expected) when the transaction managed by the EJB container commits. I have two problems I'd like to solve: 1) The exception I get is the unhelpful "javax.ejb.EJBException: Transaction aborted". If I recursively call getCause() enough times, I eventually reach the more useful "java.sql.SQLIntegrityConstraintViolationException", but this exception is part of the EclipseLink implementation and I'm not really comfortable relying on it's existence. Is there a better way to get detailed error information with JPA? 2) The EJB container insists on logging this error even though I catch it and handle it. Is there a better way to handle this error which will stop Glassfish from cluttering up my logs with useless exception information? Thanks.

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• Can I autoregister my clients/servers in local DNS?

  - by Christian Wattengård

  Right now I have a W2k12 server at home that I run as a domain controller. This has the extra benefit of registering every "subordinate" computers name in it's DNS so that I don't have to go around remembering IP's all the time. (And it let's me easily run dhcp also on my servers). I need to rework my home network for several odd reasons, and in this new scenario there is no place for a big honking W2k12 server box. I have a RasPI, and I have other smallish linux boxen I can use. (In a worst case scenario I'll use my NUC, but then I'll be forced to use my home cinema's UPnP-client for media... The HORROR!!) Is it possible to set up a DNS-server-"appliance" that somehow autoregisters it's own hostname.. Scenario: Router (N66u) on 172.20.20.1. Runs DHCP on 172.20.20.100-200 range. Server [verdant] of a *nix flavor on 172.20.20.2 Laptop [speedy] of W8 flavor on DHCP assigned Laptop [canary] of W8 flavor on DHCP assigned Desktop [lianyu] of Ubunto flavor on DHCP assigned What I would like is that all of the above servers (except possibly the router) would be available on verdant.starling.lan and canary.starling.lan and so on. This is how it works right now (except the Ubuntu box... I haven't cracked that one yet) because Windows just does this for you.. I would also be able to do this without any manual labor on the server. When I tell my box it's name is smoak it should "immediately" be available as smoak.starling.lan without any extra configuration on my part. How can I do this in a Linux (Ubuntu) environment? (Bonus comment upvote for naming the naming scheme :P )

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• Which SCM/VCS cope well with moving text between files?

  - by pfctdayelise

  We are having havoc with our project at work, because our VCS is doing some awful merging when we move information across files. The scenario is thus: You have lots of files that, say, contain information about terms from a dictionary, so you have a file for each letter of the alphabet. Users entering terms blindly follow the dictionary order, so they will put an entry like "kick the bucket" under B if that is where the dictionary happened to list it (or it might have been listed under both B, bucket and K, kick). Later, other users move the terms to their correct files. Lots of work is being done on the dictionary terms all the time. e.g. User A may have taken the B file and elaborated on the "kick the bucket" entry. User B took the B and K files, and moved the "kick the bucket" entry to the K file. Whichever order they end up getting committed in, the VCS will probably lose entries and not "figure out" that an entry has been moved. (These entries are later automatically converted to an SQL database. But they are kept in a "human friendly" form for working on them, with lots of comments, examples etc. So it is not acceptable to say "make your users enter SQL directly".) It is so bad that we have taken to almost manually merging these kinds of files now, because we can't trust our VCS. :( So what is the solution? I would love to hear that there is a VCS that could cope with this. Or a better merge algorithm? Or otherwise, maybe someone can suggest a better workflow or file arrangement to try and avoid this problem?

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• SQL with Regular Expressions vs Indexes with Logical Merging Functions

  - by geeko

  Hello Lads, I am trying to develop a complex textual search engine. I have thousands of textual pages from many books. I need to search pages that contain specified complex logical criterias. These criterias can contain virtually any compination of the following: A: Full words. B: Word roots (semilar to stems; i.e. all words with certain key letters). C: Word templates (in some languages are filled in certain templates to form various part of speech such as adjactives, past/present verbs...). D: Logical connectives: AND/OR/XOR/NOT/IF/IFF and parentheses to state priorities. Now, would it be faster to have the pages' full text in database (not indexed) and search though them all using SQL and Regular Expressions ? Or would it be better to construct indexes of word/root/template-page-location tuples. Hence, we can boost searching for individual words/roots/templates. However, it gets tricky as we interdouce logical connectives into our query. I thought of doing the following steps in such cases: 1: Seperately search for each individual words/roots/templates in the specified query. 2: On priority bases, we merge two result lists (from step 1) at a time depedning on the logical connective For example, if we are searching for "he AND (is OR was)": 1: We shall search for "he", "is" and "was" seperately and get result lists for each word. 2: Merge the result lists of "is" and "was" using the merging function OR-MERGE 3: Merge the merged result list from the OR-MERGE function with the one of "he" using the merging function AND-MERGE The result of step 3 is then returned as the result of the specified query. What do you think gurues ? Which is faster ? Any better ideas ? Thank you all in advance.

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• Passing arguments to objects created using the new operator?

  - by Abhijit

  Hi guys, I have a small C++ problem to which I don't know the best solution. I have two classes A and B as follows: class A { int n; B* b; public: A(int num): n(num) { b = new B[n]; for (int i = 0; i < n; i++) { b[i].setRef(this); } } ~A() { delete [] b; } }; class B { A* a; public: B() { } B(A* aref) { a = aref; } void setRef(A* aref) { a = aref; } }; I am creating an object of class A by passing to its constructor the number of objects of class B I want to be created. I want every object of class B to hold a pointer to the class A object that creates it. I think the best way to do this would be by passing the pointer to the class A object as a constructor argument to the class B object. However, since I'm using the new operator, the no-args constructor for class B is called. As a result, the only solution I can see here is calling the setRef(A*) method for every object of class B after it has been constructed using the new operator. Is there a better solution/design pattern that would be more applicable here? Would using placement new for class B be a better solution? Thanks in advance for your help.

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• Why does adding Crossover to my Genetic Algorithm gives me worse results?

  - by MahlerFive

  I have implemented a Genetic Algorithm to solve the Traveling Salesman Problem (TSP). When I use only mutation, I find better solutions than when I add in crossover. I know that normal crossover methods do not work for TSP, so I implemented both the Ordered Crossover and the PMX Crossover methods, and both suffer from bad results. Here are the other parameters I'm using: Mutation: Single Swap Mutation or Inverted Subsequence Mutation (as described by Tiendil here) with mutation rates tested between 1% and 25%. Selection: Roulette Wheel Selection Fitness function: 1 / distance of tour Population size: Tested 100, 200, 500, I also run the GA 5 times so that I have a variety of starting populations. Stop Condition: 2500 generations With the same dataset of 26 points, I usually get results of about 500-600 distance using purely mutation with high mutation rates. When adding crossover my results are usually in the 800 distance range. The other confusing thing is that I have also implemented a very simple Hill-Climbing algorithm to solve the problem and when I run that 1000 times (faster than running the GA 5 times) I get results around 410-450 distance, and I would expect to get better results using a GA. Any ideas as to why my GA performing worse when I add crossover? And why is it performing much worse than a simple Hill-Climb algorithm which should get stuck on local maxima as it has no way of exploring once it finds a local max?

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• Using modem for sending voice recording

  - by ircmaxell

  I've got an interesting one for you. I've been going over my server monitoring and notification systems (Nagios based), and realized that if our internet connection goes down, there's no way for it to notify me. I already have a modem listening (Via CentOS 5) on a spare POTS line so that I can dial-in in case our internet goes down. I was wondering if I could come up with a script (Shell, Python, etc) that can dial out and play a recorded message (wave file I'm guessing) when it's picked up. I know Windows supports voice calls over a voice modem, I was wondering if a solution existed for Linux... I know asterisk can probably do it, but isn't that overkill (A full blown VOIP system just for a notification mechanism that will hopefully never be used)? And wouldn't it interfere with the modem's primary function as a backup network interface (PPP spawned via mgetty)? I've done some searching, and haven't really come up with much. I know how to dial out from the command line, but only as a modem (not as voice). Worst case, I could set it up to dial out as a modem, and then just realize that if I get a call with modem sounds from that number that it's the notification... Any insight would be appreciated...

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• How to feature-detect/test for specific jQuery (and Javascript) methods/functions used

  - by Zildjoms

  good day everyone, hope yer all doin awesome am very new to javascript and jquery, and i (think) i have come up with a simple fade-in/out implementation on a site am workin on (check out http://www.s5ent.com/expandjs.html - if you have the time to check it for inefficiency or what that'd be real sweet). i use the following functions/methods/collections and i would like to do a feature test before using them. uhm.. how? or is there a better way to go about this? jQuery $ .fadeIn([duration]) .fadeOut([duration]) .attr(attributeName,value) .append(content) .each(function(index,Element)) .css(propertyName,value) .hover(handlerIn(eventObject),handlerOut(eventObject)) .stop([clearQueue],[jumpToEnd]) .parent() .eq(index) JavaScript setInterval(expression,timeout) clearInterval(timeoutId) setTimeout(expression,timeout) clearTimeout(timeoutId) i tried looking into jquery.support for the jquery ones, but i find myself running into conceptual problems with it, i.e. for fadein/fadeout, i (think i) should test for $.support.opacity, but that would be false in ie whereas ie6+ could still fairly render the fades. also am using jquery 1.2.6 coz that's enough for what i need. the support object is in 1.3. so i'm hoping to avoid dragging-in more unnecessary code if i can. i also worked with browser sniffing, no matter how frowned-upon. but that's also a bigger problem for me because of non-standard ua strings and spoofing and everything else am not aware of. so how do you guys think i should go about this? or should i even? is there a better way to go about making sure that i don't run code that'll eventually break the page? i've set it up to degrade into a css hover when javascript ain't there.. expertise needed. much appreciated, thanks guyz!

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• Best terminal environment for Cygwin/Windows?

  - by Anders Sandvig

  Today I run Cygwin with rxvt using the following startup line: rxvt -bg black -sl 8192 -fg white -sr -g 150x56 -fn "Fixedsys" -e /usr/bin/bash --login -i This gives me a resizeable native Windows window which is much better than the standard "DOS box" the default cygwin.bat provides. However, the current configuration does have a couple of issues: I am not able to enter non-ASCII characters into the terminal window (i.e. æ, ø, å and Æ, Ø, Å, which I use semi-frequently. In fact, the terminal will not even accept them when I paste them into the window. If I paste a string like "bølle" (Norwegian for "bulley"), all I get is "blle". I am not able to render UTF-8 character, they only show as ?, even if they are supported by the font (i.e. when rendering the same characters in ISO-8859-1 they show just fine.). I am running English Windows Vista with locale and keyboard layout set to Norwegian (ISO-8859-1 character set?), but I've had the exact same issue on Windows 2000 and XP. Anyone knows how to fix this (i.e. a better way to configure rxvt)? Apart from the issues mentioned above, I'm very happy with rxvt, so if I find a way to resolve them I'd like to continue using it. However, if the issues are not (easily) solvable, are the any other good terminal solutions for Cygwin? Update The solution provided by Andy and Mattias (editing the .inputrc file) did solve the input problem, but output rendering is still an issue. Output is fine when I render in ISO-8859-1, but when using UTF-8 I only get ? for non-ASCII characters. This behavior is consistent between rxvt, urxvt (under Cygwin XFree X Server), mintty and PuttyCyg. Is there a similar configuration file where output encoding can be set (i.e. the equivalent of setting output locale on a Linux system)?

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• Java resource closing

  - by Bob

  Hi, I'm writing an app that connect to a website and read one line from it. I do it like this: try{ URLConnection connection = new URL("www.example.com").openConnection(); BufferedReader rd = new BufferedReader(new InputStreamReader(connection.getInputStream())); String response = rd.readLine(); rd.close(); }catch (Exception e) { //exception handling } Is it good? I mean, I close the BufferedReader in the last line, but I do not close the InputStreamReader. Should I create a standalone InputStreamReader from the connection.getInputStream, and a BufferedReader from the standalone InputStreamReader, than close all the two readers? I think it will be better to place the closing methods in the finally block like this: InputStreamReader isr = null; BufferedReader br = null; try{ URLConnection connection = new URL("www.example.com").openConnection(); isr = new InputStreamReader(connection.getInputStream()); br = new BufferedReader(isr); String response = br.readLine(); }catch (Exception e) { //exception handling }finally{ br.close(); isr.close(); } But it is ugly, because the closing methods can throw exception, so I have to handle or throw it. Which solution is better? Or what would be the best solution?

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