intro

INTRODUCTION

Welcome to Ovrimos! The current text presents Ovrimos version 2.0. This text is less technical than a programmer's guide and is meant as a concise on-line help text for users who have just obtained a copy of Ovrimos and wish to explore the product features.

Product description

Ovrimos is
a) a complete transactional data storage and retrieval system, based on the relational database model and
b) a programmable Web server.
It is a multi-user, relational database with ODBC and JDBC connectivity, demanding relatively few resources.
The client-server architecture it is based on, allows numerous concurrent users. Moreover, Ovrimos supports CGI, PERL DBI, the Unicode character set, and is ideal for Web databases.

Ovrimos is in the same "league" as other well known and established database engines (i.e. Oracle, Microsoft SQL Server, etc.), but has some distinctive characteristics that differentiate it from the rest and render it attractive and appealing to developers, EDP managers, and end-users. The more important of the above mentioned characteristics are:

It also communicates with clients through HTTP. In fact, HTTP is used for the user/administrator interface. Consequently, all functions -i.e. the database administration and the data management via SQL commands- are executed through a Web browser. The advantage of this characteristic is the fact that both the user and the administrator are using an interface that is already familiar to them, and the product is taking advantage of the Internet browsers' ever-evolving technology.
Ovrimos has a set of built-in functions that can manage MIME-typed BLOBs and can deliver them to Web browsers as images, videos, sounds etc., without the need of any special programming code.
Ovrimos supports Unicode natively. As a consequence, the user can insert Unicode strings and retrieve them as such. Moreover, in these Unicode strings, one can apply all the functions that may be used in ASCII strings.
Up till now, all known database engines execute stored procedures using their own proprietary language. In contrast, Ovrimos executes stored procedures in C, C++, Java and Perl. The advantage is obvious, since the programmer does not need to learn any proprietary language.
Ovrimos is user friendly and easy to use, especially by administrators and developers. For example, Ovrimos administrators can monitor all activities on the SQL and HTTP server, regarding the resources used, and thus making their task of resource allocation and fine tuning considerably easier. On the other hand, the developer can easily develop applications using the tools he/she is familiar to, without having to learn new ones. As a consequence, the application development cost is reduced.
The HTTP server Ovrimos: a) supports server-side scripts, b) preserves connection states and c) can execute SQL and Scheme files as well as CGI.
Ovrimos needs few resources: a) approximately 3-4 MB of free disk space, depending on Operating System, plus 100 KB for each database is required, and b) 2 MB RAM plus 150 KB per connected session.

Ovrimos AND USER GROUPS

Administrators

Version 2.5 of Ovrimos has features that are attractive to system administrators. The main ones are:

Error Recovery. Even on the event of a power supply failure, Ovrimos will be automatically restored to the logical situation it was before the crash.
Actual on-line backup. The system administrator can take backups from the database while it is still on and fully operative.
Interactive Data Description Language.
SQL and Web Monitor. The system administrator can monitor all functions of both the SQL and the Web server -i.e. the SQL commands given by each user, the system's workload, etc.
Database fine-tuning. The system administrator can easily tune the database parameters so that optimization of database performance is possible. This operation, of course, can not be done on-line.
Database administration through the Web. It is a simple task to start, stop, create a new or delete an old database, even remotely, via a Web browser.

Developers

Ovrimos Version 2.5 is specially designed to cater to the needs of demanding developers. In view of the latter, it has advanced, and sometimes unique, features such as:

Stored procedures in C, C++, Java, and Perl. It offers AGI (Another Gateway Interface), which allows the developers to have stored procedures in the programming language of their choice (Cobol, Pascal, etc.). In order to implement the above, AGI source code is provided, so that the developers can also use their own compiler, or port it to another platform and language.
Ovrimos offers a small, robust API to communicate with the following programming languages: C, C++, Java, Perl, Scheme (a LISP dialect).
ODBC and JDBC connectivity which allows programmers that have developed applications with ODBC or JDBC interface to port them to Ovrimos.
Programmable Web Server. Developers can create HTML output, using Scheme as a script language.

ISPs

Ovrimos Version 2.5 has some distinctive advantages for ISPs:

It is both a Web and an SQL server.
Its Web server is programmable (using Scheme).
Ovrimos Web server can execute SQL scripts, which is a unique characteristic.
It supports Perl.
MIME-typed BLOBs are supported. Ovrimos has a set of built-in functions, which can manage MIME-typed BLOBs and can deliver them in Web browsers as images, videos, sounds, etc. without the need of any special programming code (unique characteristic).
Database administration through the Web. It is a simple task to start, stop, create a new or delete an old database, even remotely, via a Web browser.
It needs very few resources: a) approximately 1 to 10 MB (depending on platform) of free disk space is required, and b) 2 MB RAM plus 150 KB per connected session.

Corporate Users

There are reasons that Ovrimos is attractive to EDP managers and they should consider using it as their database platform:

It is extremely reliable and stable, has a high performance transactional engine, with built-in error recovery mechanism, while it has high availability due to on-line backup.
It is easy to learn, install, administer and use.
It complies to and supports open standards, so that the users are not locked in through proprietary standards. For example, the main known databases have stored procedures in proprietary languages, i.e. Oracle has PL/SQL, Microsoft has SQL Transact, whereas Ovrimos has stored procedures in C, C++, Java, and Perl.
It supports many hardware and Operating System platforms.

End-Users

Ovrimos Version 2.5 is very appealing to end-users as well, as:

It is user friendly: a) since it is using as interface a Web browser, so that the end-user is working in a familiar environment, b) it communicates with all known office automation applications, such as Excel, Word, Lotus, etc. with cut and paste functions and data import or export through ODBC drivers.
The end-user can easily execute SQL scripts either on client or server site, via the web browser.

FEATURES SUPPORTED IN VERSION 2.5

SQL-89 / SQL2 (SQL-92) entry level

ODBC 2.0 support

ODBC 2.0 extended SQL grammar level 2 API plus Integrity Enhancement Facility (IEF): Some extra features are: selects in FROM clauses, updateable views, scrollable cursors, privilege inheritance (roles) for easier administration.

Multi-user operation, multi-CPU support: A very large number of users may connect to each database at the same time. Only about 150 KB of RAM space is required per session, therefore the limit is practically very high.

TCP/IP: The TCP/IP protocol is used as a communication means between client and server, either in single-user or in multi-user version.

Unlimited number of records: Up to a maximum of 4 billion records per table (2^32).

Referential integrity: All data manipulation is restricted by integrity rules specified at data description time. Enforcement of the rules is automatic.

Query optimization: An optimizer uses available keys and information about tables to produce an optimized query.

Data encryption: Data encryption, based on 256 bit keys, may be applied separately on each user database. The option to encrypt is selected at database creation time.

Transactions: A sequence of operations is guaranteed to be atomic for recovery purposes. The user can accept them all (commit) or discard them all (rollback) in a single operation.

Nested transactions: Ovrimos allows nested transactions up to, theoretically, any depth. Commit or rollback of a nested transaction is performed in the confines of its outer transaction.

Error recovery: Rollback of uncommitted transactions or roll-forward of committed ones after any failure.

Simple Backup/Restore facility: Ovrimos allows automatic and fast backup and restore of user's data.

Four isolation levels: All isolation levels, as described by the SQL Standard (i.e. Read uncommitted, Read committed, Repeatable read and Serializable) are implemented.

Interactive DDL (Data Description Language): Table, index, and user creation does not have to be performed by any separate DBA program. Interactive (direct) SQL is used for all DDL operations.

C, C++ API: Programmers may develop C or C++ applications, using Ovrimos through a programmer's library.

32-bit ODBC driver: A 32-bit ODBC driver is supplied for interfacing with other products.

BLOB support: It supports Binary Large Objects (BLOBs) for storing and retrieving arbitrary sized pieces of data.

JDBC 1.1 driver: A JDBC 1.1 driver is offered.

HTTP Server: An integrated HTTP server that can publish documents pertaining to the database, or all databases (e.g. the manual), can deploy Java applets to use the database from within Web browsers, can deliver MIME-typed BLOBs using special URLs.

CGI support: The SQL terminal provided doubles as a CGI program, allowing Web application writers to integrate results from parameterized SQL scripts into HTML pages.

Stored procedures: The users are able to write stored procedures in their favorite language, using a look-alike of the corresponding interface. For example, Java users will use an interface similar to JDBC, Perl users will use an interface similar to DBI. Nick-named AGI (Another Gateway Interface), it allows centralization of the business logic in OLTP (On-line Transaction Processing) applications.

CGI: A usable subset of CGI 1.1 has been implemented.

HTML interface for the user: The user will be able to browse the database catalog, perform SQL transactions and even upload SQL files for execution, using a conventional Web browser. This is possible due to an innovative implementation of persistent HTTP sessions. No client-side cookies are used.

HTML interface for the administrator: The administrator is able to monitor active connections and statements, thread usage and HTTP sessions and even shut down the database, using a conventional Web browser.

Domains: The user can define domains: subsets of basic types using SQL constraints.

Database manager: Database administration and monitoring of several databases handled by Ovrimos will be performed via the user's favorite browser.

Unicode: Unicode support in the form of UNICODE CHAR and UNICODE VARCHAR types.

UTC/Local Time: Times and timestamps are held in UTC (a.k.a. GMT) internally, but are interpreted relative to the session timezone, set by the user.

Bulk updates: Sets of update statements, up to approximately 64 KB worth of text, can be submitted to the server for very fast execution.

Server-side scripts: Users can take advantage of persistent HTTP sessions to write entire HTML applications using Scheme.

Memory mapping: A database file-to-memory mapping mechanism enhances performance since data storage and retrieval is done in the computer's main memory.

Operating System Platforms

Despite being lightweight, Ovrimos version 2.5 has been tested successfully with large databases on both Win 32 and U*x architectures. Particularly, version 2.5 will be available in the following operating systems:

Windows NT
Linux (Intel and Alpha)
Solaris 2.x (Intel and SPARC)
IRIX (Silicon Graphics)
True64 Unix
UnixWare 2.x
FreeBSD
SCO Unix
BSDI

Differences from previous versions

A few shortcomings of the previous versions are now overcome and some new features appear in version 2.5. The main additional features of version 2.5 are the following:

Stored Procedures: The users are now able to write stored procedures in the programming language in which they are fluent, using a look-alike of the corresponding interface. For example, Java users may use an interface similar to JDBC, Perl users may use an interface similar to DBI. Nick-named AGI (Another Gateway Interface), it allows speedups of orders of magnitude in OLTP (On-line Transaction Processing).

CGI and CGI scripts: A usable subset of CGI 1.1 is implemented. Besides, Ovrimos may now execute CGI scripts without the need of a separate Web server.

HTML interface for the user: The user is now able to browse the database catalog, perform SQL transactions and even upload SQL files for execution using a conventional Web browser. This is possible thanks to the implementation of persistent HTTP sessions. The best point of the technique used is that no client-side cookies are used.

HTML interface for the administrator: The administrator is now able to shutdown the database and monitor active connections and statements, as well as HTTP sessions, using a conventional Web browser.

Server-side scripts: Users can take advantage of persistent HTTP sessions to write entire HTML applications using Scheme.

Database Manager: Database administration and monitoring of several databases handled by Ovrimos is now performed via the user's favorite browser.

Domains: The user is now able to define domains: subsets of basic data types using SQL constraints.

Unicode: Unicode support is in form of UNICODE CHAR and UNICODE VARCHAR types. The implementation of Unicode allows users to employ Unicode as easily and effectively as ASCII.

UTC/Local Time: Times and Timestamps are held in UTC (a.k.a. GMT) internally, but are interpreted relative to the user's time zone. An example that sets the time zone is explained in the SQL Appendix.

Bulk Updates: Sets of update statements, up to approximately 64k worth of text, can be submitted to the server for very fast execution.

FUTURE ENHANCEMENTS

Secure Web server (SSL support)
Table replication
Sagas (very long transactions)

Next chapter: Working Environment