Introduction to CouchDB with .NET part 5: concurrency and eventual consistency

Introduction

In the previous post we continued our discussion of the CouchDB HTTP API. In particular we looked at those endpoints that modify the database and the documents. We inserted a new database and some documents. We also saw how to update documents. An interesting feature of CouchDB is that it keeps the old versions of an updated document until the database is compacted. Document deletion marks a document with the “_deleted” flag set to true. We can still read the older versions of the document and restore it like it was before. Again, this can only be done until the database has been compacted. DB compaction generally removes old versions of a document and those documents that were marked with the “_deleted” flag. These versions are called revisions and we saw the role of revision IDs

In this post we’ll briefly discuss how concurrency is handled in CouchDB.

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Introduction to CouchDB with .NET part 4: continuing with the CouchDB HTTP API

Introduction

In the previous post we started looking into the CouchDB HTTP Web API. The API allows us to communicate with the CouchDB server using HTTP calls. This and the ubiquitous JSON arguments make integration with CouchDB quite straightforward for all platforms that are capable to execute HTTP calls and surely any serious programming language should be equipped with web request execution. The HTTP API responds with JSON by default and that also makes for a seamless integration.

We have primarily looked at various requests that did not modify the database or the documents. In this post we’ll continue with testing the database and document modification endpoints in the API.

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Introduction to CouchDB with .NET part 3: starting with the CouchDB HTTP API

Introduction

In the previous post we looked at the CouchDB administrative UI called Fauxton. The UI that shipped with earlier versions of CouchDB is called Futon so you will still come across that name if you work with older CouchDB projects. Fauxton is quite easy and straightforward to use. The database section allows us to create, update and delete databases and documents. Many functions are meant to be handled by database admins such as CouchDB users, access rights, processes and configuration.

In this post we’ll start exploring the CouchDB HTTP-based API.

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Introduction to CouchDB with .NET part 2: Fauxton UI basics

Introduction

In the previous post we laid the foundations for this series. We’ll discuss the basics of the NoSql document-based data store CouchDB. CouchDB stores its records in documents as JSON which makes integration with clients relatively easy. CouchDB comes with a web-based administrative UI that allows us to create databases, check their content, create users, administrators and many other things that we’ll eventually cover in this series. CouchDB is completely schemaless, has no data integrity checks and its JSON storage format allows us to store our domain objects in a more natural way than table-based relational databases do.

We successfully installed CouchDB on Windows. It was a straightforward and painless experience. The installer also set up a Windows Service so that the CouchDB server is up and running all the time. We had to solve one issue though after the initial setup: 3 administrative databases were not installed and we had to create them in the UI. In the absence of those tables the CouchDB server keeps logging the same exception message in the log file.

In this post we’ll be looking into various basic functions in the CouchDB management UI called Fauxton.

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Introduction to CouchDB with .NET part 1: foundations and setup

Introduction

CouchDB is a document based NoSql database by Apache written mostly in the Erlang programming language with C and C++ added in. It is also open-source and free-of-charge in both hobby and real-life commercial projects. If you’ve only worked with traditional relational databases like MS SQL with its tables, schemas, integrity checks, primary and secondary keys etc. then a document database will require a significant shift in the way you think of storing data. CouchDB shares a number of traits with MongoDB which is the most popular document based data store at this time. Both CouchDB and MongoDB store their data in documents, they don’t have any strictly enforced schema and no strict data integrity by way of secondary keys. They can both store our domain objects “as they are”, without the need of designing tables for them. In other words CouchDB represents our domain objects much closer than table-based relational databases can do. CouchDB and MongoDB can run on both Linux and Windows. Also, they can be clustered with in a master-slave setup with a primary database serves as the read/write node and the secondary databases all share the read-load. The master is then responsible for replicating data modifications such as inserts, updates and deletes to the secondary nodes.

CouchDB comes with a built-in management tool where we can view our databases and documents, edit them, delete them and perform a range of other administrative tasks. Relational databases are still the norm and the primary choice among developers for the data storage needs for their projects. However, it’s always good to know that there are alternatives that offer alternative ways of storing data. Both CouchDB and MongoDB provide fast read and write operations. CouchDB offers a REST API based query interface with the usual HTTP verbs like GET, PUT, DELETE etc. Querying can be performed with either predefined views or a new query language called Mango that was added to CouchDB 2.0.

In this series we’ll be looking at the basics of CouchDB, how to set it up on Windows, how to insert data, how to execute queries and finally how to communicate with a CouchDB database from your .NET project.

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