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23
votes
5answers
2k views

Does immutability entirely eliminate the need for locks in multi-processor programming?

Part 1 Clearly Immutability minimizes the need for locks in multi-processor programming, but does it eliminate that need, or are there instances where immutability alone is not enough? It seems to ...
0
votes
2answers
53 views

Locking techniques

Delphi RAD libraries implement many thread friendly objects in a way which forces one to declare another object for storing the reference returned by that object's locking method. The object thus ...
0
votes
1answer
97 views

sqlite trigger or application event?

I've have two event queues(table mapped queues) based on two different states of same data stored in two different tables. The events are generated on create/update/delete on both the tables. ...
0
votes
2answers
51 views

Methods to keep an external service up to date that polls your service periodically?

Sorry if the title is hard to understand, it is easier if I describe the scenario to get the question across. I have a service that collects data, performs business logic and does all the normal ...
1
vote
0answers
924 views

Solutions for iOS collaborative sync (iCloud CoreData, CouchDB)?

I'm developing an iOS app where one of the features will be allowing users to share and collaborate on data (e.g. lists). From everything I've read and based on the way that iCloud CoreData sync works ...
1
vote
3answers
198 views

A pattern to “atomically” update a pair of objects

Is there a standard pattern in OOP to kind of "atomically" update a pair of objects, like a pair of bank accounts on a transaction? I would like to have somehow a single public method exposed that ...
0
votes
0answers
104 views

Numerous Sync/Async calls to webservice from hybrid app

I have a requirement where I have to make numerous calls to webservice to update the local database. Since I have to support lower-end Android phones also, I'm not yet sure as to how this would be ...
7
votes
2answers
8k views

When should I use StringBuilder or StringBuffer?

In a production web application, my fellow programmers used StringBuffer everywhere. Now I am taking care of application development and corrections. After reading StringBuilder and StringBuffer I ...
1
vote
2answers
148 views

An algorithm for a synchronization

I want to make a synchronization. What's the algorithm for it in a nutshell? 1) A client reads a local data and sends them to a server afterwards. The server compares them with its actual data, ...
7
votes
5answers
3k views

How best do you represent a bi-directional sync in a REST api?

Assuming a system where there's a Web Application with a resource, and a reference to a remote application with another similar resource, how do you represent a bi-directional sync action which ...
3
votes
4answers
3k views

How would you approach developing a Hotel Reservation System?

Till now, I have had the experience of developing either a desktop application or a Website. But, with this Hotel reservation system, I am interfacing a problem that needs both. The application ...
13
votes
8answers
11k views

Multithreading synchronization interview question: Find n words given m threads

I came across this question: You are given a paragraph , which contain n number of words, you are given m threads. What you need to do is , each thread should print one word and give the ...
0
votes
0answers
39 views

How to replicate state update to all the nodes in middle-ware cluster?

I am developing a middle-ware components that receives a stream of self-contained events. If event corresponds to a business rule a notification is generated. A system outgrew vertical scaling and it ...
1
vote
1answer
693 views

How to make a method synchronized across all instances of an object

Today I was asked this interview question and could not answer. : If you have two instances of a Person Object and each of them have a setAddres method that is synchronized. Now if it was only one ...
1
vote
3answers
273 views

Synchronization in the given Code

I had an interview few weeks back, and I was asked to write a code with Setters and Getters. I had written the following code; // Just an example Class ABC{ private int num; public void ...
0
votes
1answer
73 views

Implementation details of database synchronisation API

I want to achieve a database synchronisation between my server database and a client application. The server would run MySQL and the applications may run different database technologies, their ...
4
votes
2answers
745 views

Ideas for Offline & Sync Across Multiple Platforms [closed]

I'm looking for some implementation ideas to be able to have offline apps sync data to a central server. The server will be Sql Server 2008. The clients will download data from the server when ...
2
votes
1answer
249 views

Difference between mutex in windows and linux

Is that correct that a mutex object in Linux cannot be used for cross process synchronization as opposed to its Windows counterpart? If that is true - what was the idea to limit mutex synchronisation ...
2
votes
4answers
584 views

Best practice to sync long paths to filesystems where path length is limited?

I wrote a sync tool to synchronize folders/files from Alfresco to Windows. PROBLEM: In Alfresco, /files/can/have/very/very/very/long/filepaths/like/this.txt The Windows API prevents me from creating ...
4
votes
2answers
343 views

caching on multiple servers

Because we need to keep response times low, we get tons of requests, and we need to basically process ALMOST the same data (which I'll refer to as X) each request (the inputs are different though, so ...
0
votes
1answer
126 views

The best approach to building a mobile service that's also available when the connection drops?

Hopefully this question will be a good suit for P.SE since it is a whiteboard-level 'how can this be done' conceptual question. I'm trying to build a product that needs to be available to someone on ...
0
votes
3answers
221 views

Keeping SQL Server DB Up to date in Team environment [duplicate]

We are working in a Visual Studio Environment using TFS. When developers get the latest source code it includes a copy of the 'update' sql scripts for the database of the application. The challenge ...
2
votes
2answers
382 views

Is it a bad idea to sync file system with remote server using HTTP?

I have started a project which will duplicate Dropbox or Google Drive behavior but using Amazon S3 az a backend. Idea is very simple, a Node.js server that watchs a directory for file changes and PUT ...
1
vote
2answers
126 views

Path of Replication

I'm currently developing a replication system to keep data in-synch between an arbitrary number of servers. Some of these servers exist in one cluster on one LAN. Others exist somewhere else in the ...
8
votes
1answer
682 views

HTML5 video sprites

I'm currently working on a project where there is a requirement to dynamically composite multiple synchronised video sources onto a single canvas. The initial prototype I put together loaded the video ...
3
votes
5answers
2k views

Is it possible to half-way synchronize javascript functions that include async calls?

I am wondering if there exists a way to half way synchronize javascript functions, where data is requested on the fly. I don't want to make it purely blocking (which I guess is impossible), I just ...
1
vote
6answers
718 views

why no hasLock/testLock on mutexes

looking through the docs of posix' pthread_mutex_t and window's mutex and CRITICAL_SECTION I noticed there is no easy way of checking whether the current thread holds a specific mutex posix' ...
8
votes
2answers
1k views

Is it time to deprecate synchronized, wait and notify?

Is there a single scenario (other than compatibility with ancient JVMs) where using synchronized is preferable to using a Lock? Can anyone justify using wait or notify over the newer systems? Is ...
0
votes
1answer
193 views

Synchronize Azure SQL (cloud) with Azure SQL Emulator (local)?

We have an Azure service (web role) that heavily depends on the database. For offline development/testing, we'd like to have the app+db run offline within the emulators. Running the webrole itself ...
5
votes
1answer
302 views

What's a good scheme for multi-user database synchronization?

I'm working on a system to allow multiple users to collaborate on an online project. Everything is fairly straightforward, except for keeping the users in sync. Each user has their own local copy of ...
0
votes
2answers
485 views

Syncing objects to a remote server, and caching on local storage

What's the best method of sycing objects (as JSON) to a remote server, with local caching? I have some objects that will pretty much just be plain-text with some extra meta-data. I was thinking of ...
2
votes
1answer
294 views

Does Dropbox use a cronjob to sync up? [closed]

I was looking into lipsync on a Dropbox clone. I was looking at the diagram on how it works here. It shows that a cronjob is used to keep files in sync between client and server. Does that mean that ...
7
votes
3answers
393 views

How do most sync programs monitor file changes?

Do sync programs like Dropbox typically track file changes by doing byte by byte comparisons, or using hashes, or using diff / keeping local commit logs like version control, or what?
4
votes
1answer
1k views

What is a good design pattern / lib for iOS 5 to synchronize with a web service?

We are developing an iOS application that needs to synchronize with a remote server using web services. The existing web services have an "operations" style rather than REST (implemented in WCF but ...
0
votes
1answer
608 views

Best way to update UI when dealing with data synchronization

I'm working on a bug at work. The app is written in Objective-C for iOS based device, for the iPad. I'm the new guy there and I've been given a hard task. Sometimes, the UIButton text property does ...
12
votes
2answers
3k views

Conflict resolution for two-way sync

How do you manage two-way synchronization between a 'main' database server and many 'secondary' servers, in particular conflict resolution, assuming a connection is not always available? For example, ...
6
votes
1answer
2k views

Atomic Memcache Operations in PHP

This post is a follow up to this question: http://stackoverflow.com/questions/10626904/php-atomic-memcache/10627226 Considering I am using Memcache (no d at the end) on PHP 5.3.10, I implemented a ...
3
votes
5answers
354 views

New application development - Use existing database or create a new one?

A Client has a huge Windows Application running on a Database. This client wants you to develop an "Express" version of this application, including only, let's say, 20% of its features. This Express ...
16
votes
2answers
8k views

Best practice/Patterns for two way data synchronisation

Quite often in my work the idea of 2-way data synchronisation between database systems crops up. The classic example is two slightly different CRM systems (say, Raiser's Edge and Salesforce) and the ...
12
votes
1answer
3k views

Redis vs Zookeeper

It seems silly to compare these two servers considering that they're meant for very different things. But if you think about it, they can do lots of similar things: store configuration data, ...
5
votes
2answers
1k views

How to sync calendars events programmatically?

I'd like to hear some ideas how to sync calendar events. Say I have two calendars having fields (id, title, start, end, updated, location and description). I'm struggling with starting point. Its easy ...
2
votes
3answers
249 views

Offline data that will need imported later

My existing application is a .NET 3.0 winform app that talks to a WCF service which in turn updates a MS SQL Server database; I can make changes at all spots (Windows client, WCF, server). I've had an ...
3
votes
1answer
745 views

synchronization web service methodologies or papers

I am building a web service (PHP+JSON) to sync with my iphone app. The main goals are: Backup Provide a web view for printing / sorting, manipulating. allow a group sync up and down. I am aware of ...
3
votes
3answers
207 views

How to improve enterprise level application that consists of only static methods

I am new in a enterprise level application project and discovered that 99% of everything I've seen in code is static methods, static properties. The application at hand is a distributed app ...
4
votes
3answers
749 views

How to do data synchronisation between two applications?

Our client has a CRM application (let's call it A) and a custom built Windows application (VB.NET) (let's call it B) that directly writes to and reads from the CRM database. Application A is used ...
1
vote
2answers
611 views

Multithreaded UI desktop application issues

I am involved into development a rich UI project: desktop windows application. Application uses asynchronous invocations and in its turn it should be ready to process external messages (events). The ...