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Alfresco architecture

At the core of the Alfresco system is a repository supported by a server that persists content, metadata, associations, and full text indexes. Programming interfaces support multiple languages and protocols upon which developers can create custom applications and solutions. Out-of-the-box applications provide standard solutions such as document management, records management and web content management.

As an entirely Java application, the Alfresco system runs on virtually any system that can run Java Enterprise Edition. At the core is the Spring platform, providing the ability to modularize functionality, such as versioning, security, and rules. Alfresco uses scripting to simplify adding new functionality and developing new programming interfaces. This portion of the architecture is known as web scripts and can be used for both data and presentation services. The lightweight architecture is easy to download, install, and deploy.

There are many ways to slice and deploy Alfresco, however most deployments follow a general pattern. Ultimately, Alfresco is used to implement ECM solutions, such as Document Management (DM), Web Content Management (WCM), Records Management (RM), and Digital Asset Management (DAM). Across those solutions may also be elements of collaboration and search.

The solutions are typically split between clients and server, where clients offer users a user interface to the solution and the server provides content management services and storage. Solutions commonly offer multiple clients against a shared server, where each client is tailored for the environment in which it is used.

The following figure shows various architectural components.

Clients

Alfresco offers two primary web-based clients: Alfresco Share and Alfresco Explorer.

  • Alfresco Share can be deployed to its own tier separate from the Alfresco content application server. Alfresco Share focuses on the collaboration aspects of content management and streamlining the user experience. Alfresco Share is implemented using Spring Surf and can be customized without JSF knowledge.
  • Alfresco Explorer is deployed as part of the Alfresco content application server. It is a highly customizable power-user client that exposes all features of the Alfresco content application server and is implemented using Java Server Faces (JSF).

Clients also exist for portals (via JSR-168 portlets), mobile platforms, Microsoft Office, and the desktop. A client often overlooked is the folder drive of the operating system, where users share documents through a network drive. Using JLAN technology, Alfresco can look and act just like a folder drive. JLAN is the only Java server-side implementation of the CIFS protocol, letting users interact with Alfresco as they do any other normal file drive except the content is now stored and managed in the Alfresco content application server.

Server

The Alfresco content application server comprises a content repository and value-added services for building ECM solutions. Two standards define the content repository: CMIS (Content Management Interoperability Services) and JCR (Java Content Repository / JSR-170/286). These standards provide a specification for content definition and storage, content retrieval, versioning, and permissions. Complying with these standards provides a reliable, scalable, and efficient implementation.

The Alfresco content application server provides the following categories of services built upon the content repository:
  • Content services (transformation, tagging, metadata extraction)
  • Control services (workflow, records management, change sets)
  • Collaboration services (social graph, activities, wiki)

Clients communicate with the Alfresco content application server and its services through numerous supported protocols. HTTP and SOAP offer programmatic access while CIFS, FTP, WebDAV, IMAP, and Microsoft SharePoint protocols offer application access. The Alfresco installer provides an out-of-the-box prepackaged deployment where the Alfresco content application server (with embedded Alfresco Explorer) and Alfresco Share are deployed as distinct web applications inside Apache Tomcat.