08 junio 2008

ISIS3 - what is ISIS-NBP - nugget 2

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Sent: Saturday, June 07, 2008 12:24 PM
Subject: ISIS3 - what is ISIS-NBP - nugget 2

In the last ISIS-NBP nugget [1,2], we have briefly introduced the project's goals and architecture. Today we begin to explain the concept of the ISIS-NBP Cell.

 |        Databases            |
 |           |                 |
 |  Console---Engine---Gateway |

The ISIS-NBP Cell is a toolset that should be installed or deployed all together, guaranteeing the presence of a minimum functionality set. This means that, after an ISIS-NBP Cell is deployed, the user always have four elements available: Databases, Engine, Console and Gateway.

Let us examine each of ISIS-NBP cell components:

Engine is the logic processing unit, the Cell's heart and soul that binds all other components together. It is invisible for the end-users, but it is her that makes everything work. Moreover, the Engine was designed to be extensible by means of a plug-in system. Therefore, developers can implement add-ons or plug-ins to add missing functionality to the Cell. The Cell is not monolithic and immutable software, but can be extended to incrementally accommodate new user demands.

Databases are encapsulated data repositories and organized by collections. Encapsulation means that any access to data files must undergo one of the Cell's interfaces: namely the Gateway or the Console. These interfaces shield the users from delving into technical details about the databases in use, if they do not want to. Moreover, databases are grouped into named collections. One clear benefit of this approach is avoiding path issues. For example, when some database files are moved from one position to another in the file system their path changes, but not the name of the collection that they belong to. That is one of the reasons why ISIS-NBP applications should "talk" to a Cell, not to their underlying database files.

Console is an interactive environment to allow users direct data manipulation in an user friendly fashion. Users can inspect and browse collections, databases, records and fields. For example, the expression below represents the field (tag) 26 in the first records from the cds database belonging to the sample collection:

      In:  sample.cds[1][26]

    Out: ^aParis^bUnesco^c-1965

Power users can use the Console to do maintenance, execute commands or even run scripts. The Console has the same power of expression present in a full-fledged programming language. In future nuggets, we are going to explain in details what can be achieved in the Console and how. 

Gateway is the other Cell interface providing a standard set of services for remote (network) access, cross-cell and external systems interoperability. The Gateway allows users to open remote interactive consoles and manipulate data as if they were logged in the same machine where the Cell is installed. Two or more different Cells can talk to each other to execute backups or synchronize their data. Users can use regular Internet browsers to navigate through some Cell's databases. Any of these tasks can be accomplished by means of the Gateway component.

For the time being, there is support for authenticated remote console access (using ssh) and web browsing data (using HTTP). Developers might be glad to know that support for a XML-RPC API is underway, making it possible to create client applications in many programming languages. Other protocols should be supported in the near future.

This e-mail is a teaser, the second of a series that will give further details about the ISIS-NBP Cell, the project goals and development status quo. In the references section below, we give you pointers to previous nuggets.

ISIS-NBP will be presented during the 3rd World Meeting of ISIS

See Congress Site in: http://www.eventos.bvsalud.org/agendas/isis3/?lang=en


 [1] First Isis-NBP nugget

     [2] ISIS-NBP = ISIS new based platform, is the new architecture of ISIS developed by BIREME.

This note was prepared by Rodrigo Sienra, consultant of ISIS-NBP project.

  | |  Ernesto Spinak                | |   | |  spinaker@adinet.com.uy        | |   | |  Montevideo, Uruguay           | |   | |  tel/fax  (5982) 622-3352      | |   | |  celular  (598)  99612238      | |  

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