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  • Choosing a distributed shared memory solution

    - by mindas
    I have a task to build a prototype for a massively scalable distributed shared memory (DSM) app. The prototype would only serve as a proof-of-concept, but I want to spend my time most effectively by picking the components which would be used in the real solution later on. The aim of this solution is to take data input from an external source, churn it and make the result available for a number of frontends. Those "frontends" would just take the data from the cache and serve it without extra processing. The amount of frontend hits on this data can literally be millions per second. The data itself is very volatile; it can (and does) change quite rapidly. However the frontends should see "old" data until the newest has been processed and cached. The processing and writing is done by a single (redundant) node while other nodes only read the data. In other words: no read-through behaviour. I was looking into solutions like memcached however this particular one doesn't fulfil all our requirements which are listed below: The solution must at least have Java client API which is reasonably well maintained as the rest of app is written in Java and we are seasoned Java developers; The solution must be totally elastic: it should be possible to add new nodes without restarting other nodes in the cluster; The solution must be able to handle failover. Yes, I realize this means some overhead, but the overall served data size isn't big (1G max) so this shouldn't be a problem. By "failover" I mean seamless execution without hardcoding/changing server IP address(es) like in memcached clients when a node goes down; Ideally it should be possible to specify the degree of data overlapping (e.g. how many copies of the same data should be stored in the DSM cluster); There is no need to permanently store all the data but there might be a need of post-processing of some of the data (e.g. serialization to the DB). Price. Obviously we prefer free/open source but we're happy to pay a reasonable amount if a solution is worth it. In any way, paid 24hr/day support contract is a must. The whole thing has to be hosted in our data centers so SaaS offerings like Amazon SimpleDB are out of scope. We would only consider this if no other options would be available. Ideally the solution would be strictly consistent (as in CAP); however, eventual consistence can be considered as an option. Thanks in advance for any ideas.

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  • How stable are Cisco IOS OIDs for querying data with SNMP across different model devices?

    - by Daniel Papasian
    I'm querying a bunch of information from cisco switches using SNMP. For instance, I'm pulling information on neighbors detected using CDP by doing an snmpwalk on .1.3.6.1.4.1.9.9.23 Can I use this OID across different cisco models? What pitfalls should I be aware of? To me, I'm a little uneasy about using numeric OIDs - it seems like I should be using a MIB database or something and using the named OIDs, in order to gain cross-device compatibility, but perhaps I'm just imagining the need for that.

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  • Call to a member function num_rows() on a non-object

    - by Patrick
    I need to get the number of rows of a query (so I can paginate results). As I'm learning codeigniter (and OO php) I wanted to try and chain a -num_rows() to the query, but it doesn't work: //this works: $data['count'] = count($this->events->findEvents($data['date'], $data['keyword'])); //the following doesn't work and generates // Fatal Error: Call to a member function num_rows() on a non-object $data['count2'] = $this->events->findEvents($data['date'], $data['keyword'])->num_rows(); the model returns an array of objects, and I think this is the reason why I can't use a method on it. function findEvents($date, $keyword, $limit = NULL, $offset = NULL) { $data = array(); $this->db->select('events.*, venues.*, events.venue AS venue_id'); $this->db->join('venues', 'events.venue = venues.id'); if ($date) { $this->db->where('date', $date); } if ($keyword) { $this->db->like('events.description', $keyword); $this->db->or_like('venues.description', $keyword); $this->db->or_like('band', $keyword); $this->db->or_like('venues.venue', $keyword); $this->db->or_like('genre', $keyword); } $this->db->order_by('date', 'DESC'); $this->db->order_by('events.priority', 'DESC'); $this->db->limit($limit, $offset); //for pagination purposes $Q = $this->db->get('events'); if ($Q->num_rows() > 0) { foreach ($Q->result() as $row) { $data[] = $row; } } $Q->free_result(); return $data; } Is there anything that i can do to be able to use it? EG, instead of $data[] = $row; I should use another (OO) syntax?

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  • Sending data from one Protocol to another Protocol in Twisted?

    - by veb
    Hi! One of my protocols is connected to a server, and with the output of that I'd like to send it to the other protocol. I need to access the 'msg' method in ClassA from ClassB but I keep getting: exceptions.AttributeError: 'NoneType' object has no attribute 'write' Actual code: http://pastebin.com/MQPhduSY Any ideas please? :-)

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  • How does Bitmap.Save(Stream, ImageFormat) format the data?

    - by Matt Jacobsen
    I have a non transparent, colour bitmap with length 2480 and width 3507. Using Bitmap.GetPixel(int x, int y) I am able to get the colour information of each pixel in the bitmap. If I squirt the bitmap into a byte[]: MemoryStream ms = new MemoryStream(); bmp.Save(ms, ImageFormat.Bmp); ms.Position = 0; byte[] bytes = ms.ToArray(); then I'd expect to have the same information, i.e. I can go to bytes[1000] and read the colour information for that pixel. It turns out that my array of bytes is larger than I anticipated. I thought I'd get an array with 2480 x 3507 = 8697360 elements. Instead I get an array with 8698438 elements - some sort of header I presume. In what format the bytes in my array stored? Is there a header 1078 bytes long followed by Alpha, Red, Green, Blue values for every byte element, or something else?

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  • Is the first persistance of an Entity Data Model in EF 4.0 slower due to the connection cost ?

    - by Scott Davies
    Hi, I've got a console app written that persists an object graph via Entity Framework 4.0. I loop through this to dump the execution times for each persistance. The first persistance is always the largest. Is this due to EF making the initial connection to the database and/or JIT'ing ? Here's a sample of the output: Persisted graph in **3318** millseconds. Persisted graph in 25 millseconds. Persisted graph in 26 millseconds. Persisted graph in 22 millseconds. Thanks, Scott

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  • How to get max of composite data in SQL?

    - by Siddharth Sinha
    SELECT "Name""Month","Year","Value" from Table WHERE "Name" LIKE '%JERRY%' AND "Year" = (SELECT MAX("Year") FROM Table where "Name" LIKE '%JERRY%') AND "Month"= (SELECT MAX("Month") FROM Table where "Name" LIKE '%JERRY%' AND "Year"= (SELECT MAX("Year") FROM Table where "Name" LIKE '%JERRY%')) Table -- Name | Year | Month | Value ----------------------------- JERRY 2012 9 100 JERRY 2012 9 120 JERRY 2012 9 130 JERRY 2012 8 20 JERRY 2011 12 50 So i want the first three rows as output. As for the latest month for the latest year i need all the values. Can someone suggest a better cleaner query?

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  • Why can't I include these data files in a Python distribution using distutils?

    - by froadie
    I'm writing a setup.py file for a Python project so that I can distribute it. The aim is to eventually create a .egg file, but I'm trying to get it to work first with distutils and a regular .zip. This is an eclipse pydev project and my file structure is something like this: ProjectName src somePackage module1.py module2.py ... config propsFile1.ini propsFile2.ini propsFile3.ini setup.py Here's my setup.py code so far: from distutils.core import setup setup(name='ProjectName', version='1.0', packages=['somePackage'], data_files = [('config', ['..\config\propsFile1.ini', '..\config\propsFile2.ini', '..\config\propsFile3.ini'])] ) When I run this (with sdist as a command line parameter), a .zip file gets generated with all the python files - but the config files are not included. I thought that this code: data_files = [('config', ['..\config\propsFile1.ini', '..\config\propsFile2.ini', '..\config\propsFile3.ini'])] indicates that those 3 specified config files should be copied to a "config" directory in the zip distribution. Why is this code not accomplishing anything? What am I doing wrong? (I have also tried playing around with the paths of the config files... But nothing seems to help. Would Python throw an error or warning if the path was incorrect / file was not found?)

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  • How do you read data from a ADODB stream in ASP as byte values?

    - by user89691
    I have an ASP routine that gets a binary file's contents and writes it to a stream. The intention is to read it from the stream and process it st the server. So I have: ResponseBody = SomeRequest (SomeURL) ; var BinaryInputStream = Server.CreateObject ("ADODB.Stream") ; BinaryInputStream.Type = 1 ; // binary BinaryInputStream.Open ; BinaryInputStream.Write (ResponseBody) ; BinaryInputStream.Position = 0 ; var DataByte = BinaryInputStream.Read (1) ; Response.Write (typeof (DataByte)) ; // displays "unknown" How do I get the byte value of the byte I have just read from the stream? Asc () and byte () don't work (JScript) TIA

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  • Why does this data YYYY-MM-DD regex fail in Java?

    - by ProfessionalAmateur
    Hello StackOverFlow, My first question and Im excited... I've lurked since go-live and love the site, however I apologize for any newbie errors, formatting, etc... I'm attempting to validate the format of a string field that contains a date in Java. We will receive the date in a string, I will validate its format before parsing it into a real Date object. The format being passed in is in the YYYY-MM-DD format. However I'm stuck on one of my tests, if I pass in "1999-12-33" the test will fail (as it should with a day number 33) with this incomplete pattern: ((19|20)\\d{2})-([1-9]|0[1-9]|1[0-2])-([12][0-9]|3[01]) However as soon as I add the characters in bold below it passes the test (but should not) ((19|20)\\d{2})-([1-9]|0[1-9]|1[0-2])-(0[1-9]|[1-9]|[12][0-9]|3[01]) *additional note, I know I can change the 0[1-9]|[1-9] into 0?[1-9] but I wanted to break everything down to its most simple format to try and find why this isn't working. Here is the scrap test I've put together to run through all the different date scenarios: import java.util.regex.Matcher; import java.util.regex.Pattern; public class scrapTest { public scrapTest() { } public static void main(String[] args) { scrapTest a = new scrapTest(); boolean flag = a.verfiyDateFormat("1999-12-33"); } private boolean verfiyDateFormat(String dateStr){ Pattern datePattern = Pattern.compile("((19|20)\\d{2})-([1-9]|0[1-9]|1[0-2])-(0[1-9]|[1-9]|[12][0-9]|3[01])"); Matcher dateMatcher = datePattern.matcher(dateStr); if(!dateMatcher.find()){ System.out.println("Invalid date format!!! -> " + dateStr); return false; } System.out.println("Valid date format."); return true; } } Ive been programming for ~10 years but extremely new to Java, so please feel free to explain anything as elementary as you see fit.

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  • Is frozenset adequate for caching of symmetric input data in a python dict?

    - by Debilski
    The title more or less says it all: I have a function which takes symmetric input in two arguments, e.g. something like def f(a1, a2): return heavy_stuff(abs(a1 - a2)) Now, I want to introduce some caching method. Would it be correct / pythonic / reasonably efficient to do something like this: cache = {} def g(a1, a2): return cache.setdefault(frozenset((tuple(a1), tuple(a2))), f(a1, a2)) Or would there be some better way?

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  • onselect in one combo it changes data dynamically in other combo?

    - by ajay
    Hello sir I am new to the jsp and ajax world. my problem is If i select one combo option then it should change the other combo options dynamically without submit button press. for example if i select the country then it should shows their states in other combo. I am using servlet & JSP and MS-ACCESS as backend. please reply as soon as possible. THANKING YOU....

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  • Is the Keychain suitable for storing general data, such as strings?

    - by cannyboy
    The Keychain seems to be used a lot for usernames and passwords, but is it a good idea to use it for other sensitive stuff (bank details, ID numbers etc), but with no password? What kind of encryption does the keychain use? The scenario I'm concerned about is a thief acquiring an iPhone (which is screen-locked) and being able to access the file system to get this info. Also, would using the Keychain involve export restrictions due to the use of encryption?

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  • Rails - Vestal Versions - Access previous version data w/o restoring?

    - by AnApprentice
    Hello, I'd like to use vestal versions to do the following: Determine the Content of the current record being saved Determine the Content of the last record saved In my model I have: class Note < ActiveRecord::Base versioned :if => :really_create_a_version? def really_create_a_version? XXXXXXXXXXXXXX XXXXXXXXXXXXXX end end Where the XXXX are, how can I get the note.content of the item about to be saved (i'm assuming it hasn't been saved yet to the DB? Is that correct? Also, how can I get the note.content of the save before the current save in progress? Thanks

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  • How to give default values for the sum, count if no data exist in mysql query which uses group by?

    - by Salil
    I am using following query which works fine for me except one problem SELECT f.period as month, sum(p.revenue * ((100-q.rate)/100)) as revenue ,count(distinct q.label) as tot_stmt FROM files f, reports p, rates q,albums a where f.period in ('2010-06-01','2010-05-01','2010-04-01','2010-03-01') and f.period_closed = true and q.period = f.period and a.id = q.album_id and p.file_id = f.id and p.upc = a.upc and p.revenue is not null GROUP BY month ORDER BY month DESC O/P = month            revenue     tot_stmt 2010-06-01     10.00         2 2010-05-01     340.47       2 I want result like following month            revenue     tot_stmt 2010-06-01     10.00         2 2010-05-01     340.47       2 2010-04-01     0.00           0 2010-03-01     0.00           0 Regards, Salil Gaikwad

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  • SQL query for getting data in two fields from one column.

    - by AmiT
    I have a table [Tbl1] containing two fields. ID as int And TextValue as nvarchar(max) Suppose there are 7 records. I need a resultset that has two columns Text1 and Text2. The Text1 should have first 4 records and Text2 should have remaining 3 records. [Tbl1] ID | TextValue 1. | Apple 2. | Mango 3. | Orange 4. | Pineapple 5. | Banana 6. | Grapes 7. | Sapota Now, the result-set should have Text1 | Text2 Apple | Banana Mango | Grapes Orange | Sapota Pineapple |

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  • How to update a table using a select group by in a second one as the data source in MySQL?

    - by Jader Dias
    I can't do this in MySQL UPDATE tableA, tableB SET tableA.column1 = SUM(tableB.column2) WHERE tableA.column3 = tableB.column4 GROUP BY tableB.column4 ; Neither can I UPDATE tableA, ( SELECT SUM(tableB.column2) sumB, tableB.column4 FROM tableB GROUP BY tableB.column4 ) t1 SET tableA.column1 = sumB WHERE tableA.column3 = column4 ; Besides it being illegal code, I think you can understand what I tried to do with the queries above. Both of them had the same intent. How can I do that in MySQL?

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  • How to do filtering data in UITableView like 'Recents' view in Phone application?

    - by Teerasej
    Hi, everyone. I am planning to applied the feature like 'Recents' view in Phone application of iPhone. This view show option on the top, 'All' and 'Missed'. Default option is 'All' but if you tap 'Missed' option the entry in UITableView which aren't 'Missed call' will slide out and disappear. This is the good feature. So I know you can help me by suggest or guide me some idea (any article is good too). I try to googling around but I couldn't find any good one.

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