In computer science, persistence refers to the characteristic of state that outlives the process that created it. From Wikipedia: http://en.wikipedia.org/wiki/Persistence_%28computer_science%29

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NSUserDefaults, Core Data or neither?

Everytime I press a certain button, it should remove a random index from a dictionary and then save that dictionary everytime its modified. I have done this using NSUserDefaults. I have found that ...
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Maintaining consistency with loosely coupled business and data layers

Take the following sequence of events: Business layer requests data x and y from data layer. Data layer returns version 1 of x and y. Business layer starts performing logic based on data x and y. ...
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How to correctly model aggregation with respect to persistence?

When modeling bigger domain entities you will probably have some kind of relation between these entities. These relations will usually result in entities referencing different entities. If i am not ...
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19 views

Message persistence in Message Queues

I have looked into several message queues as referenced in this link. Several of the larger and more popular ones are in memory only. I can understand the need for this in some situations however in ...
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Is there a practical reason not to use a .NET “setting” to store data that is not a setting?

.NET applications developed using Visual Studio have an easy way to store and recover user settings. You can add the default value of a setting in a special class and have read/write access to it at ...
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47 views

When do I prefer a local DB over serialization for local data storage?

I recently started developing a small calendar application, in which I can add and view several calendar entries, which contain several data like name, date, alarm settings and so on. Those values ...
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Saving tabular, spreadsheet-like data in a relational database?

I'm hoping this question isn't too broad or too prone to opinionated answers, since I could really use some pointers. I'm trying to come up with a way to persist tabular, spreadsheet-like1, data in a ...
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112 views

Persistence Strategies - Filling a cache strategy

Let's say I have an interface IDataAccessObject<TSource> with CRUD methods to access a data source. I have an implementation StrategyDataAccessObject<TSource>, which uses an strategy ...
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1answer
173 views

Enterprise Architecture: Where to put persistence/dbContext management? [closed]

I'm working on architecting a somewhat enterprise-level solution and have a question about how to best handle the persistence details. My overall setup is that there's a core set of business logic/...
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253 views

Persistence models for Event Sourcing

I am intrigued by the Event Sourcing pattern but am struggling to design an event sourcing model and put it in concrete form. First off, I want to make sure that I understand the main use cases of ...
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What data type should Gateway return in Repository Pattern to eliminate refactoring when switching persistence mechanisms?

Following this description of the Repository Pattern, we have three main concerns that need their own classes: The "Repository," which takes and returns Domain Models. The "Gateway," which takes ...
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Persisting and manipulating JS ArrayBuffer data on the server

My node.js app has to deal with (sometimes large; a few MB) tables of numerical data. I'm about to use JavaScript's native binary objects for this purpose (i.e. ArrayBuffer and friends), because they'...
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191 views

iOS Best practice for handling model objects

There are different levels I'm asking this question at. Case 1: Let's think about the typical drill-down design. Say a table view controller has an array of custom objects, and tapping a cell will ...
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DDD – duplicity between Aggregates – should I use one table?

I understand that there exists duplicity of data between Bounded Contexts. The thing is that I'm not really sure about duplicity of data between Aggregate roots. Example: I have product in Product ...
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137 views

Rich client persistence without a database

We have a pretty sizable .NET rich client app that currently uses nHibernate and Firebird embedded for persistence. Due to the nature of the app, we need to load the entire database into memory when ...
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186 views

Is there a detriment to using SQLite over a pList for persistence?

I'm making a fairly simple application and I've got a settings menu that stores times and some boolean values. I have the application storing and retrieving data already but I started to wonder if ...
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189 views

DDD using an ORM and a Active Directory Server for Persistence

With Domain Driven Design one would model out the domain. One would then use an ORM of some sort to take care of the persistence. Say you have a Product entity which has a Name, SKU and an Owner. This ...
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Strategies for maintaining backwards compatibility when persisting objects to XML [duplicate]

I am using XStream to persist Java objects to files. This works fine and so far I have had no problems. However, in the course of development, the objects have changed. Some new properties have been ...
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1answer
49 views

Do my “dal” and “fileHandler” interfaces overlap?

I want my program to: read some input lines from CSV file write the output lines to plain string file read some input from the same file in (2) and compare it to some calculated data I want to ...
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1answer
176 views

Persist data downloaded by Celery workers

I'm working in a tool that downloads tweets from Twitter to process them later. For this purpose I'm using Celery with RabbitMQ, sending task with the keywords that must be tracked by the workers. My ...
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1answer
307 views

Creating/updating entity save strategy

Please note: although I'm talking about Java in this question, what I'm asking about here should really be language-agnostic. I am dabbling in OR/M for the first time, and have cooked up the ...
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229 views

How do you keep your motivation and enthusiasm for a never ending project? [closed]

At the beginning of a project I tend to finish tasks quickly. However, after a while I start getting bored doing the same thing over and over again. It feels like I am stagnant. How do you keep ...
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1answer
119 views

What programmable system can provide persistent scheduling? [closed]

I want to write an application that creates scheduled events at specific times. When the delay elapses the event notifies the application. The scheduled events must not be stored in the application's ...
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Decimal vs. Integer; Given a fixed range of values, which is preferable for accurate computation?

After getting into a "heated discussion" with someone, I figured I'd ask this question for the sake of posterity. I'm willing to be corrected if my assumption is incorrect but I'd like to hear a ...
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78 views

How to collect industry usage of data persistence technologies? [closed]

In our organization, we are using various data access/persistence technologies in different projects. The ones used till now are Hibernate, JPA, Spring Data JPA, JDBC, Spring JDBC, MyBatis, and ...
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195 views

Structural pattern for an unconventional use of a database

I'm writing a game client as a personal project and using using it as a vehicle to learn about Java database access, specifically Neo4j, and possibly Spring Data Neo4j if I decide it's appropriate. I'...
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246 views

Should my internal MVC/MVVM application use Web Services for Persistence?

Just talking about internal applications or intranet web apps... At some companies I've seen their business-logic piece (Model in MVC/VM in MVVM) on one (or both) sides of a Web Service. And on the ...
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Which approach would be better for persisting these overridable configuration keys and values? A simple key-value store, or a graph database?

I'm creating a system where there are config keys and values. So for example: config.key = 10 Is an example of a configuration key and a value. These keys can also have overrides based on "...
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What's a good way to make sure that locally serialized data can be deserialized in newer code?

Context: I'm working on an HTML 5 game without persisted state. Every time you refresh the page, you start at the beginning. People are requesting that they can start where they left off if they ...
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613 views

Can a version of Python's shelve module that knows when its entries have been modified be written in any programming language?

shelve is a Python module that makes it easy to persist a Python dictionary to disk (under the right conditions). The documentation for shelve gives this example to demonstrate one of the pitfalls of ...
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271 views

Manage the persistence of entities on iOS in several places: CoreData on the device, iCloud and on a REST API

For the needs of a project, I would persist the datas contained in Core Data in several places depending on the state of the user. If the user is logged to my API -> Persist the datas on my API. ...
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772 views

What are the bad points of using Core Data for iOS like an ORM

I just starting to use Core Data for my iOS app and I am thinking about how use Core Data for my needs. What are the features of my app: The user look for products proposed from a catalog. The user ...
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122 views

Persist AJAX values [closed]

I have a simulator that pulls data from a DB - calculates and return JSON result to an ajax call that renders a table for the results. The calculation procedure are as follow: grab X number of data ...
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93 views

Persisting type in Java - should I be using flags?

Is there some specific piece of advice around persist values that indicate type? Specifically I want to know if I should persist a flag/state indicating the type in persistence or not. I get the ...
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Persistence frameworks and common sense

I have studied some persistence frameworks mainly Hibernate, DORM, TMS Aurelius and I'm wondering. In a model of type: TOrderFiscal < > ----- > Items < > -------- > TOrderItem ------...
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How do I make a domain model that doesn't violate OOP?

My game reads a number of JSON files, deserializes them, and hands the resulting objects off to the classes that need them. These deserialized objects, which can be thought of as the domain model, are ...
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DDD and the persistence of value objects; must we denormalize?

I've been reading up a lot on Domain-Driven Development, and I came to the question of how to preserve lack of distinct identity with value objects (VOs). While in the DDD world, this is a requirement ...
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What's the easiest (quickest) way to share one dataset in my app with someone else

I have some javascript that creates a canvas image that I want users to be able to share. I simply need to save the image somehow. Nothing else. I've been contemplating using bits and pieces of ruby ...
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Can I share ~1k of dynamically updated data between HTML5/JS pages using only apache2?

I have an HTML5/Javascript web site. There is a form which updates JSON data. There are other pages which I would like to load that JSON data dynamically. I know how to do this via Tomcat/JSP but I'd ...
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How can I implement a modular “save” function for a game?

I have to implement a method to save my game in such a way that I can change the storage medium with the change of only a single variable. Ideally I'd use an interface to designate the required ...
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2k views

Best Practices for serializing/persisting String Object Dictionary entities

I'm noticing a trend towards using a dictionary of string to object (or sometimes string to string), instead of strongly typed objects. For example, the new Katana project makes heavy use of ...
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473 views

Workflow versioning

I believe I have a fundamental misunderstanding when it comes to workflow engines which I would appreciate if you could help me sort out. I'm not sure if my misunderstanding is specific to the ...
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What is a Ruby on Rails way to save images?

I develop on iOS, and I'm switching from a PHP backend to Ruby on Rails. The interchange format is JSON. A quick Google search for 'save images in Rails' has nearly every result talking about saving ...
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1k views

Does 'consider returning Null Object' apply to a DAO read method?

I was looking for an answer to the question of what a DAO should return when a search ends up to be for an entity that does not exist. There are some generic previous questions related to returning ...
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210 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 ...
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4answers
505 views

Is storing types in the database an anti pattern?

A little background on where this question is coming from. In my current .NET application I'm working on some features related to archiving a certain type of business entity called a "Project". ...
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4answers
326 views

Senior team members want to move query-relevant persistent data from DB to cache. Does this make sense?

I am a young engineer recently employed at a small company that sells products to the general public. We use Ruby On Rails and MySQL. Our database has a lot of customer data, but a great deal more of "...
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In agile development, should I try persistence in flat file before database?

Somebody explained to me that since in agile development, policy and the application logic should be more important than details such as persistence method, persistence decision should be taken at the ...
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How do I design a DAL when I have to deal with relationships?

Say I'm developing a bug tracker, where a ticket belongs to at most one milestone, and a milestone can have many tickets. When a milestone is deleted (from the database), all tickets associated with ...
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Patterns for a tree of persistent data with multiple storage options?

I have a real-world problem which I'll try to abstract into an illustrative example. So imagine I have data objects in a tree, where parent objects can access children, and children can access ...