{"id":2120,"date":"2016-01-13T17:12:16","date_gmt":"2016-01-13T17:12:16","guid":{"rendered":"https:\/\/www.couchbase.com\/blog\/?p=2120"},"modified":"2016-01-13T17:12:16","modified_gmt":"2016-01-13T17:12:16","slug":"storing-blobs-in-couchbase-for-content-management","status":"publish","type":"post","link":"https:\/\/www.couchbase.com\/blog\/storing-blobs-in-couchbase-for-content-management\/","title":{"rendered":"Storing Blobs in Couchbase for Content Management"},"content":{"rendered":"

This blog was originally posted on Cecile Le Pape's personal blog. To see to original blog post, click\u00a0here<\/a>.\u00a0<\/em><\/p>\n

\u00a0<\/p>\n

In my previous post<\/a>, I talked about how to setup a flexible content management service using Couchbase as the metadata repository, on top of an Apache Chemistry server. The blobs themselves (pdf, pptx, docx, etc) are stored in a separate file system or in a blob store. Today, I would like to show how Couchbase can be used to store the blobs themselves, using a custom chunk manager. The idea is to store not only the metadata of a document (date of creation, creator, name, etc.) but in addition the blob itself.<\/p>\n

The purpose of this new architecture is to reduce the number of different systems (and licences to pay) and also to benefit directly from the replication features offered by Couchbase.<\/p>\n

First, let\u2019s remember that Couchbase is not a blob store. This a memory-based document store, with an adhoc cache management tuned so that most of the data stored in Couchbase should be in RAM for fast querying. Data are also replicated between nodes (if replication is enabled) inside the cluster and optionnaly outside the cluster if XDCR is used. This is why data stored in Couchbase can not be larger than 20 MB. This is a hard limit, and in real life 1MB is already a large document to store.<\/p>\n

Knowing that, the point is: how can I store large binary data in Couchbase ? Simple answer: chunk it!<\/p>\n

The new architecture looks now like this:<\/p>\n

<\/p>\n

There is now 2 buckets in Couchbase:<\/p>\n

    \n
  1. cmismeta<\/em> : used to store metadata<\/li>\n
  2. cmisstore<\/em> : used to store blobs<\/li>\n<\/ol>\n

    \u00a0<\/p>\n

    When a folder is created, only the bucket cmismeta is modified with a new entry because of course, a folder is not associated to any blob. This is simply a structure used by the user to organise the documents and navigate in the folder tree. Folders are virtuals. The entry point of the structure is the root folder as described previously<\/a>.<\/p>\n

    When a document (for instance a pdf or a pptx) is inserted into a folder, 3 things happen:<\/p>\n