Data Access Interfaces

Virtuoso .NET Data Provider

virtuoso.docs@openlinksw.com — Wed, 09 Apr 2008 14:35:56 GMT

A .NET Data Provider is a set of classes that provide database access for .NET applications. There are two .NET Data Providers for Virtuoso. Each of the Virtuoso providers reside in their own namespace and assembly. The difference between them is that one relies on the Virtuoso ODBC driver for communication with the server while another doesn't involve any intermediary unmanaged layers and performs all the communication with the server using managed code only. The ODBC-based provider depends on virtodbc.dll to function properly. Note that it calls the dll directly bypassing the ODBC Driver Manager so when an application uses the ODBC-based provider the ODBC-driver dll should also be in the PATH.

Interactive SQL Utility

virtuoso.docs@openlinksw.com — Wed, 09 Apr 2008 14:35:56 GMT

ISQL/ISQLO/ISQLU/isql-iodbc/isql-udbc The Virtuoso ISQL utility allows users to execute queries & scripts against the Virtuoso or other SQL servers (depending on the suffix). It also supports a large number of options and it's own commands. ISQL parses it's input for CREATE (PROCEDURE|TRIGGER|FUNCTION), '{', '}', ';', double and single quotes and comments to detect where the current command starts and finishes. If it's in a PROCEDURE|TRIGGER|FUNCTION declaration it changes it's command line prompt to '()' to help the user enter the correct command. Otherwise it considers semicolon (;) as the statement end and executes the statement.

Virtuoso Driver for ODBC

virtuoso.docs@openlinksw.com — Wed, 09 Apr 2008 14:35:56 GMT

Virtuoso Driver for JDBC

virtuoso.docs@openlinksw.com — Wed, 09 Apr 2008 14:35:56 GMT

The Virtuoso Drivers for JDBC are available in "jar" file formats for JDBC 1.x, JDBC 2.x and JDBC 3.x specifications. These are Type 4 Drivers implying that utilization is simply a case of adding the relevant "jar" file to your CLASSPATH and then providing an appropriate JDBC URL format in order to establish a JDBC session with a local or remote Virtuoso server. It is important to note that when you make a JDBC connection to a Virtuoso Server, you do also have access to Native and External Virtuoso tables. Thus, you actually have a type 4 JDBC Driver for any number of different database types that have been linked into Virtuoso. The JDBC 2 and JDBC 3 drivers also incorporate SSL encryption to enable very secure connections to the Virtuoso database.

OLE DB Provider for Virtuoso

virtuoso.docs@openlinksw.com — Wed, 09 Apr 2008 14:35:56 GMT

OLE DB is an open data access technology developed and promoted by Microsoft. It allows for uniform data access across diverse data sources including but not limited to conventional RDBMSes. Based on the COM architecture it provides very flexible and exhaustive set of interfaces any database application developer might ever need. At the same time, OLE DB is somewhat overcomplicated and therefore is rarely used directly. In the majority of cases people use ADO(+) instead, ADO is another, somewhat simpler, of Microsoft's data access technologies. However, ADO itself is based upon OLE DB, thus those who use ADO make indirect use of OLE DB as well. With the advent of ADO.NET, OLE DB is no longer as an much essential part of the overall Microsoft data access architecture as it used to be. However it still remains important and useful working together with the Microsoft OLE DB .NET Data Provider. The OLE DB Provider for Virtuoso (VIRTOLEDB) gives OLE DB and ADO applications access to the Virtuoso databases. In principle, the same thing is possible through the conjunction of the Virtuoso ODBC driver and Microsoft OLE DB Provider for ODBC. However, VIRTOLEDB provides native OLE DB access which is more complete and more efficient. Therefore it is preferable for this purpose.

Virtuoso In-Process Client

virtuoso.docs@openlinksw.com — Wed, 09 Apr 2008 14:35:56 GMT

The in-process client is an efficient mechanism used by hosted applications to access the database functionality of the hosting Virtuoso server. Normally applications access Virtuoso using the remote procedure call mechanism hidden behind some sort of higher-level API such as ADO.NET, ODBC, and so on. The RPC based mechanism is the only available interface for non-hosted applications. For hosted applications, when the application and the DBMS server reside in the same OS process, Virtuoso provides a mechanism based on direct in-process procedure calls. The in-process call mechanism by itself is not exposed to the applications. It is hidden behind the same APIs as the RPC one: ODBC, JDBC, ADO.NET. So in both cases applications deal with the same APIs and the application logic does not change. The application chooses which mechanism to use when it opens a database connection.

Unix Domain Socket Connections

virtuoso.docs@openlinksw.com — Wed, 09 Apr 2008 14:35:56 GMT

Client connections to Virtuoso servers running on the same Unix or Linux server host can benefit from faster connections utilizing Unix Domain Sockets. This does not apply to Windows platforms. By default Virtuoso will open a Unix Domain listen socket in addition to the TCP listen socket. The name of the UD socket will be: When a client attempts to connect to the Virtuoso server using the specific address localhost it will first try connecting to the UD socket, failing that it will silently revert to the TCP socket.