3. Ovrimos Components

This chapter is an introduction to the components of Ovrimos. Short descriptions of the components and the ways Ovrimos may be used are presented here.

The notion of an Ovrimos connection  is described toward the end of the chapter. This information will help you decide on the number of connections required for working with Ovrimos.

  
3.1 Ovrimos at a glance

 

Figure 3.1 presents the Ovrimos components, the types of users (i.e. dbman, admin, end-user, developer) and the kind of usage (i.e. interactive, script, via a library, in HTTP environment etc.) of each component.

  

Figure 3.1: Ovrimos components

3.2 The Ovrimos Server

The Ovrimos core consists of an SQL Server, an HTTP Server and a Database Manager program.

SQL Terminal, Roadmap and Administrator Console are integrated parts of Ovrimos, allowing interaction with the databases through the use of a Web browser.

  
3.2.1 The SQL Server

Ovrimos allows you to create and manage databases and, in general, store, update, and retrieve data in relational schemata, either with the use of SQL statements and scripts or with your favorite application (EXCEL, DELPHI etc.) via ODBC. Java applets, Scheme scripts, and Application programs may also address Ovrimos for storage, handling and retrieval of relational data.

  
3.2.2 The HTTP Server

The HTTP server is an integrated part of Ovrimos. It allows you to communicate with Ovrimos databases through any Web browser. All other activities, requiring a Web server, may be conducted seamlessly through Ovrimos, at the same time the database applications are running.

  
3.2.3 Database Manager

All database management, i.e. creation, deletion, starting and stopping, editing of database properties etc., is performed by the Database Manager daemon process. You can access Database Manager through any Web browser.

The person who may access Database Manager is user dbman. Authentication is required for connecting to the Database Manager. When the authentication dialog box appears, type dbman for User Name  and pass   for Password. We recommend that you change this password as soon as you log in.

More on Database Manager in 4.(The Database Manager).

  
3.2.4 SQL Terminal

SQL Terminal allows you to execute SQL statements for data definition  and data manipulation . Statements are executed interactively, but SQL scripts too are submitted to the SQL Terminal. You can use the SQL Terminal through any Web browser.

All authorized database users may access SQL Terminal. Initially, there is only one user, authorized to log in. This is user admin. When the authentication dialog box appears for the first time, type admin for User Name  and pegasus   for Password . We recommend that you change this password as soon as you log in, by using the UPDATE USER statement. See also B.4.(Supported SQL Statements).

More on SQL Terminal in 5.(SQL Terminal).

  
3.2.5 Roadmap

Roadmap is a graphical, tree-like display of the database catalog objects, i.e. users, tables and views. Objects are displayed to the required level of detail. You can access Roadmap through any Web browser.

Every authorized database user has access to some of the database objects, while only admin is authorized to view information about database users.

More on Roadmap in 6.(Roadmap).

   
3.2.6 Administrator Console

The Administrator Console is designed for an easy monitoring of database resource usage (connections etc.). You can use the Administrator Console through any Web browser.

Only admin is authorized to use Administrator Console.

More on Administrator Console in 7.(Administrator Console).

  
3.3 The SQL Query Tool

The SQL Query Tool is a powerful, although somewhat primitive tool, for interactive SQL statement and batch SQL script execution. SQL Query Tool is run from the command line (i.e. DOS prompt from WIN32 and terminal line from U*ix)

There is a great deal of overlap between what you can do with SQL Terminal and SQL Query Tool.

Any authorized database user may use SQL Query Tool.

More on SQL Query Tool in 9.(SQL Query Tool). See also 5.(SQL Terminal).

  
3.4 The ODBC Interface

Ovrimos allows Open Database Connectivity through an ODBC driver. ODBC compatible programs may use the Ovrimos databases after installing the ODBC driver.

More on ODBC driver installation and usage in 10.1.(ODBC).

  
3.5 The JDBC Interface

Ovrimos allows Java Database Connectivity though a JDBC driver. This is a type 4 JDBC driver (all-Java native protocol driver), conforming to JDBC 1.1. specifications. The JDBC driver is copied by the installation program and does not require a special installation procedure. The user may execute applications as well as stored procedures written in Java. More on JDBC driver installation and usage in 10.2.(JDBC).

3.6 Users favorite languages

  
3.6.1 C, C++

Since C and C++ do not define an interface for connection with databases, Ovrimos provides a library of functions to connect to and use Ovrimos databases by C application programs.

The description of C library functions is beyond the scope of this documentation, therefore, it is not provided here. Interested users/developers are urged to contact support@ovrimos.com

  
3.6.2 Perl

Perl already defines an interface for database connection. Ovrimos provides users with a DBI driver, which is very simple to install.

More on DBI installation and usage of Perl with Ovrimos in 10.3.(DBI).

  
3.6.3 Scheme

Ovrimos has a built-in Scheme interpreter. It is, therefore, possible to execute Scheme scripts. These scripts have Scheme statements and may contain HTML or any other kind of output. The script is executed by the Ovrimos server.

For more information on running Scheme, see 8.5.2.(Scheme scripts).

   
3.7 Database Connections

The notion of a connection, although somewhat technical, is discussed briefly at this point to let users know early how many connections they may require for their working environment needs. The maximum number of concurrent connections is determined by the user's purchased license .

3.7.1 What is a connection

A connection starts when you establish communication between a client of Ovrimos and the Ovrimos Server. Every data transfer occurs during a connection. Connections are made from the following Ovrimos components:

• SQL Terminal

  SQL Terminal makes long-lived connections. These connections are terminated when you explicitly Disconnect from SQL Terminal. Quitting the browser through which you have accessed SQL Terminal does not terminate the connection, but idle connections are terminated after their allotted time has expired. See HTTPSESSIONTIMEOUT in A.2.2.(Database parameters).

  One more connection is required by SQL Terminal every time you upload a script. The lifespan of this connection is the duration of the script execution.

• Roadmap. Here the connections are short-lived, lasting only for the duration of the request.

  No connection is required for viewing table information from Roadmap.

• SQL Query Tool
  SQL Query Tool also makes long-term connections. These connections are terminated when you quit SQL Query Tool.

• Connections are also required by all other programs that communicate with Ovrimos, via ODBC, JDBC, DBI, client libraries, etc. In this case, the duration and the number of connections are determined by the application program.

  When Scheme scripts with SQL statements are executed, a connection is required. Scheme scripts without SQL statements require no connections.

  There is no extra connection for running a stored procedure. See also 10.5.(Stored Procedures).

The number of concurrent connections you have acquired when purchasing the license applies to each database created. As an example, if you have purchased a 10-connection license, you may have as many as 10 open connections (concurrent connections) to each database at a time. This is true for every database you create. If you have 5 databases, and your license allows 10 concurrent connections, you can have as many as $5\times10=50$ concurrent connections maximum (10 connections per database maximum).