FAQ

License - GPL or negotiated commercial license. See nplicense.txt

Client Component - The client is written in Java and requires a Java Runtime Environment (JRE) compatible with the OS you run it on. A CD distribution may contain an embedded JRE. A download distribution will require you to download various components and install them. See download.html for the required packages. Once you have them see client-install.html.

File format - DataView stores local tables as compressed xml using gzip compression and gives them an extension of .tbl or .mtbl for linked tables. Sample data is included with the download. The free programming editor jEdit can be used to edit data files then by hand. On Unix based systems you can read them with the "less" command.

Server Component - The server component is implemented as a Java Servlet with a few supporting classes. It requires a servlet runner which can be connected through an Apache module (recommended for ssl) or run standalone. It must be able to connect to a server database using a JDBC driver. The current version uses MySQL but other databases can be used - one class may need to be modified.

Demo server - The readme.txt file included in the download provides information on how to access a sample account on a demo server. The demo account allows you to download sample tables, run Merge and Update but not upload files.

Remote error messages - Common error messages sent back to the DataView client:
IllegalAccessException - requested operation requires a higher privilege level
SaxException - the request or response has xml format errors
Server error - these numbers have meanings that correspond to to standard http error codes.
If the server component has debug on it will write detailed msgs to the servlet error logs.

Transport protocol - The DataView client sends database requests as compressed xml over http or https and the server responds with compressed xml. File request use a slightly different protocol that combines xml request and response sections with binary file transfer. If the transport protocols change before version 1.0 you will need to download a new dataview-version.jar file and drop it into your databaveiw/lib or dataview/jre/lib/ext directory.

SSL - DataView can connect via https if the client JRE accepts the server certificate as valid. Certificates that are signed by Verisign, Thawte or other commercial vendors are normally accepted. You can import your own self signed certificate into the JRE using command line tools provided with the JRE. See docs/server-certs.html for more detail. NOTE: if you bundle a JRE with DataView you only have to do this once for all copies you distribute to your company employees.

User realms - The first time you connect to a DataView server you must enter a realm, username and password. These are checked in a dvuser table and if the user has sufficient privilege for the operation they are requesting the process is run with a database connection obtained from a pool that has the same name as the realm. The connection may have access to more than one database name depending on how you set up your connection privileges on the database server.

Local database - The DataView client can connect directly to a database server on your local machine or LAN using a JDBC connection. Connection parameters are stored in a *.pool file that you can load or unload from the menu. This is handy for intranets or testing but does not support file tranfers or verify DataView application users. See docs/advanced-localdb.html for more information.

Data Encryption - The DataView client can encrypt files, tables or specific columns with symmetric keys. To enable AES encryption you must download the "Unlimited Strength Jurisdiction Policy Files" from Sun and install them in the client JRE. See download.html. NOTE: if you bundle a JRE with DataView you only have to do this once for all copies you distribute to your company employees.

Public/Private Key Encryption - DataView can use a public key to create a package that can only be decrypted by the recipient's private Key. To enable public/private keys you must download a crypto package from bouncycastle.org and install it in your classpath. See download.html. NOTE: if you bundle a JRE with DataView you only have to do this once for all copies you distribute to your company employees.

Default encryption keys - Default encryption keys are designed to protect your data from common thieves but not from government agencies with powerful computing resources. AES data keys are 256 bits. Public/Private keys are 2048 bits. Password based keys that protect them on your local hard disk or USB device are 168 bits. If you need stronger encryption you can create new classes that implemenet DataView encryption interfaces with stronger algorithms and larger keys.

Updated: 3/21/2005