This appendix covers some basic technical issues that are of use to INTV! users.

The sections include:

• The FLEXlm licensing system
• IP Multicast and TTL Value
• Graphics file formats

MDL employs version 3.0 of Globetrotter Software’s (formerly Highland Software) Flexible License Manager (FLEXlm) for license key management. FLEXlm allows for node-locked and floating software licenses available anywhere on the network instead of only for a specific workstation. Floating licenses enable users to make more efficient use of fewer licenses by sharing among several systems.

The four main components of licensing are

• the License Manager daemon (lmgrd)
• the vendor daemon (insoftd)
• the license file (license.dat)
• the software to be licensed

The License Manager daemon (lmgrd) is in charge of initiating the vendor daemon (insoftd) and handling initial contact with the MDL software. There is a daemon running for each vendor who has a FLEXlm licensed product on the network. The vendor daemon keeps track of how many licenses are checked out, verifies encryption codes, and checks expiration dates. The software communicates with the MDL’s vendor daemon (insoftd) to verify licensing before proceeding. The vendor daemon checks to see if any licenses are available and then accepts or denies the request.

Normally, the License Manager daemon is started during the boot process in either the /etc/rc.InSoftLicense or /etc/init.d/lmgrd script depending on your platform. The License Manager uses the license file specified by the -c switch. The license file is read into memory when the daemon is first started. To incorporate changes made to the license.dat file, you must stop and restart the License Manager daemon. To stop the daemon, first determine the pid of the License Manager, lmgrd. Then, use the kill command to force the lmgrd process to exit. You should also check for the insoftd process, using the same method, and kill it if it is still running.

To start the daemon, either reboot or run the appropriate boot script manually.

The license file is used by the license daemon to determine several important facts about licensing. Normally, the license.dat file is located in the etc/ subdirectory in Communique!’s Install Directory, but it may be elsewhere if you have decided to relocate it. The license.dat file contains one SERVER line, one DAEMON line per vendor, and multiple FEATURE lines.

SERVER nodename hostid port-number

SERVER lines specify the host that will be acting as the License Server. The id is the workstation’s hostid (not hostname). The port number 5150 is determined by MDL and normally should not be changed. An example of a typical SERVER line is show below:

SERVER lonestar 80325305 5150

DAEMON daemon-name path options

The DAEMON line specifies the vendor daemon to be used. The path should be the full path and filename of the daemon. The available options are described in Globetrotter’s "FLEXlm End User Manual". A typical DAEMON is shown below.

DAEMON insoftd /opt/insoft/intv/bin/<arch>/insoftd

where <arch> specifies your machine’s architecture, either sunos, solaris, or hpux.

FEATURE name daemon version expdate number code "vendor string" hostid

Each FEATURE line specifies licensing information for an available feature that may be requested by the MDL software. Currently the following features are supported:

opendve.engine—allows the user to run the ISconferenceEngine process. The ISconferenceEngine is essential for using OpenDVE applications like INTV!. Each user running INTV! requires an opendve.engine license.

intv.chooser—An INTV! chooser license allows you to run the INTV! Media Chooser on the workstation.

intv.station—An INTV! station license allows you to run the INTV! Station software on the workstation.

The version specifies the version of the vender daemon, not of the application software. INTV! 2.0 uses version 4.000 of the MDL vendor daemon. Do not change this value.

MDL does not use the vendor field. The string field should be set to an empty string,

The trailing hostid is used only if the license is node-locked. A typical FEATURE line is shown below.

FEATURE cpendve.engine insoftd 4.000 01-jan-00 1 BB6C3264DA440D48848F "" 80123405

Trailing hostids are not used for floating licenses.

If you have other products that use the FLEXlm license management system at your site, you may wish to merge your license files together. By combining your licenses, you will have only one license.dat file and one lmgrd process running on a central server. This is not a requirement, because you could run multiple lmgrd processes on the same node, each serving licenses for a particular product or group of products. If you want to run only one License Server, there are several factors to consider:

1. Each license.dat file should have only one SERVER line, unless you are running redundant servers.

2. Each FEATURE line lists a vendor daemon that it uses to communicate with the vendor’s products. MDL’s daemon is called insoftd. You should include a DAEMON line for insoftd.

3. The path to the MDL daemon, as listed on the DAEMON line, must be accessible to the License Server.

4. MDL currently uses version 3.0 of the FLEXlm licensing product. Previous releases of the lmgrd will not function correctly with MDL products.

If you need more information about the FLEXlm licensing system, the "FLEXlm End User Manual" is available from Globetrotter Software, (408) 255-5616.

Multicast is a networking technology that reduces duplication of network data. Most networking schemes would send a copy of a Station’s audio and video signal to each receiver using the INTV! Media Chooser. If you have 11 people viewing an INTV! broadcast, then normal TCP/IP would have to send out 11 video signals and 11 audio signals. Multicast enables INTV! to send out only one stream of video data and one stream of audio data regardless of the number of viewers.

Multicast packets are received only by workstations interested in the packets. In this case, workstations running INTV! Media Choosers receive multicast packets transmitted by Stations. This "packet filtering" is done in low-level hardware, not by the CPU.

For multicast to function correctly, an explicit route to the multicast address must be defined so that the workstation will recognize it as a valid local address. The multicast address is normally 224.0.0.0. The route is normally added to /etc/rc.local during installation, and is done with the following command:

route add "224.0.0.0" hostname 0

Time To Live (TTL) is an attribute of IP multicast that defines how far a multicast packet travels out across the network. Each time a multicast packets travels through a gateway, its TTL value is decremented by 1. Some gateways may decrement the TTL value by 2, 3, or more to control the distribution of multicast packets. Although there are no set standards for TTL values, there are a few conventions that have been established:

1 Restrict the packets to the local subnet

32 Restrict the packets to the site

64 Restrict the packets to the region

128 Restrict the packets to the continent

256 Do not restrict the packets travel at all

You will want to use the lowest TTL possible to avoid wasting bandwidth on uninterested segments of your network.

The Graphics Interchange Format (GIF) was created by Compuserve and is now a widely supported format. Most PC, Macintosh, and UNIX programs that read and write graphics data support GIF.

One limitation to GIF is that files are limited to 8-bit color (256 colors). If you save a 24-bit image in GIF, the image will be dithered down to an 8-bit image with 256 colors. GIF uses a moderate compression scheme that produces files much smaller then Windows BMP, but in most cases larger than files created by the JPEG file format.

JPEG or JFIF files use the JPEG compression algorithm developed by the Joint Photographic Experts Group. The JPEG file format is not as widely supported as GIF and TIFF, but it is becoming more popular.

The JPEG format can store 24-bit color images (16.7 million colors) and achieves incredible compression ratios. There are two drawbacks to using the JPEG format for your files, however.

First JPEG employs lossy compression. To achieve such dramatic compression levels, JPEG removes image data which may result in a slight decrease in image clarity. Typically, this loss in quality is not noticed by the unaided eye, even for photographic or real world images, but you will not want to use JPEG when fine image details should not be lost.

The second drawback to JPEG is speed. JPEG files take longer to load and save than with other formats. This delay may become an issue if you are using a relatively slow computer or are working with large images.

The PCX format developed by ZSoft is used primarily on MS-DOS, Microsoft Windows, and Windows NT platforms. Most applications running on PCs support the PCX format.

PCX can store up to 24-bit color images (16.7 million colors). It employs a simple, lossless compression scheme that is very fast to decode but can produce files of considerable size, especially for 24-bit images.

The SGI image library format is used primarily on Silicon Graphics UNIX workstations. Most applications running on SGI machines will support the SGI format, but applications designed for other platforms are unlikely to support it.

The SGI image library format can store 24-bit images (16.7 million colors). INTV! writes the simplest form of the SGI image library format without using file compression to ensure compatibility with other applications. This can produce files of considerable size, especially for 24-bit images.

The Sun Raster format is used primarily on Sun Microsystems UNIX workstations. Most applications running on Sun machines, and many on other UNIX platforms, support the Sun Raster format; but PC and Macintosh applications are unlikely to support it.

The Sun Raster format can store 24-bit color images (16.7 million colors). INTV! uses the simplest form of Sun Raster file compression to ensure compatibility with other applications. This method employs a lossless run length encoded compression scheme which is very fast to decode but can produce files of considerable size, especially for 24-bit images.

The Targa (or TGA) format is used primarily on MS-DOS, Microsoft Windows, and Windows NT platforms. The Targa format is supported mainly by high-end graphics applications, especially those packages dealing with scanners, frame grabbers, and ray tracing.

The Targa format can store up to 32-bit color images. It employs a simple, lossless run length encoded compression scheme that is very fast to decode but can produce files of considerable size, especially for 24- and 32-bit images.

The Tagged Image File Format (TIFF) is a widely supported format storing up to 24-bit color images (16.7 million colors). INTV! uses the simplest form of TIFF file compression to ensure compatibility with other applications. This form employs a simple, lossless compression scheme that is very fast to decode but can produce files of considerable size, especially for 24-bit images.

The X Window Dump (XWD) format is used by UNIX workstations running X Windows. INTV! writes files in the XWD format and will read XWD files created by other applications, such as the UNIX command xwd.

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