From: Hoff Hoffman [hoffman@xdelta.zko.dec.nospam] Sent: Thursday, July 03, 2003 1:14 PM To: Info-VAX@Mvb.Saic.Com Subject: OpenVMS Frequently Asked Questions (FAQ), Part 5/9 Files NOTE: All ATA-related disk sizes listed in this section are stated in units of "disk (base ten) gigabytes" (1 GB = 10^9 bytes) and NOT in units of "software (base two) gigabytes" (1 GB = 2^30 (1073741824.) bytes. See Section 14.26. Be aware that larger disks that are using an extension of SCSI-2- disks that are using a mode page field that the SCSI-2 specifications normally reserved for tape devices-to permit a larger disk volume size will require a SCSI driver update for OpenVMS, and this change is part of V7.1-2 and later, and also part of ALPSCSI07_062 and later. (These larger disks disks will typically report a DRVERR, or will see the volume size "rounded down".) SCSI disks larger than 16777216 blocks cira 8.455 GB (base ten); 8GB (base two) require this ECO, or require the use of OpenVMS Alpha V7.1-2 or later. Applications written in C can be limited to file sizes of two gigabytes and less, as a result of the use of longword values within C file operations, and specifically off_t. This restriction is lifted in OpenVMS V7.3-1 and later, and with the application of the C ECO kits available for specific earlier releases. The use of a longword for off_t restricts applications using native C I/O to file sizes of two gigabytes or less, or these applications must use native RMS or XQP calls for specific operations. Also see Section 14.14, Section 14.26. __________________________________________________________ 9.6 What is the maximum file size, and the RMS record size limit? RMS can store individual files of a size up to the maximum supported volume size. Under OpenVMS V6.0 and later, the volume size and the RMS maximum file size limit is 2**31 * 512 bytes-one terabyte (1 TB). "Use a volume set to provide a large, homogeneous public file space. You must use a volume set to create files that are larger than a single physical disk volume. (The file system attempts to balance the load 9-6 Files on the volume sets, for example, by creating new files on the volume that is the least full at the time.)" "You can add volumes to an existing volume set at any time. The maximum number of volumes in a volume set is 255." The RMS formats-sequential, relative, and indexed- are limited by the one terabyte maximum volume size. RMS relative files are further limited to a number of records that will fit in 32 bits-4 billion records. Sequential and indexed formats do not have a record limit. Also see Section 10.14, Section 14.26. __________________________________________________________ 9.7 How do I write CD-Recordable or DVD media on OpenVMS? How to create CD-R, CD-RW, DVD-R, DVD+R, DVD-RW, or DVD+RW media on OpenVMS? o Acquire a comparatively recent SCSI-based or ATA (IDE) CD-R or DVD-R/RW or DVD+R/RW drive. Older drives can be problematic, while newer drives are readily available, cheap and very fast. o Get LDDRIVER from the Freeware. Versions of LDDRIVER are latent in OpenVMS Alpha V7.3-1 and later. (Look within SYS$MANAGER:CDRECORD.COM for details.) o Get CDRECORD or CDWRITE or other similar recording tool. (CDRECORD and CDWRITE are freely available, though versions are not on the Freeware V5.0 distribition; the URLs are referenced later in this section). Versions of CDRECORD are latent in OpenVMS Alpha V7.3-1 and later. o Build the contents of the disk on the LD device partition. o Use the CDRECORD or CDWRITE or other tool to record the contents of the LD partition directly onto the CD-R or CD-RW media. 9-7 Files Alternatively, consider the following command on OpenVMS Alpha V7.3-1 and later: @SYS$MANAGER:CDRECORD.COM HELP While folks have had success getting PC-based CD-R/RW or DVD-R/RW or DVD+R/RW tools to work with OpenVMS partitions, it is far easier and more reliable to use the OpenVMS-based versions of these tools and directly- attached devices. More details: Creation of CD recordable or DVD recordable media under OpenVMS typically involves one of two approaches: the use of the optional CD-R (`Scribe') capabilities available for the InfoServer or other "offline" hardware packages (PC-based packages will be included in this), or the use of a host-based package such as the CDRECORD or CDWRITE13_VMS or other utilities, OpenVMS ports of common open-source tools made available by Dr. Eberhard Heuser-Hofmann and others. OpenVMS can read ODS-2, ODS-5, and ISO-9960 format CD-ROMs. (If you are very careful, you can create a dual-format CD-R; a CD-R with both ODS-2 and ISO-9660 or both ODS-5 and ISO-9660 or both.) InfoServer hardware configurations are no longer available from HP, but may potentially be acquired through other means; as used equipment. http://www.geocities.com/SiliconValley/Lakes/9999/vmscdwri.html Additional information is available at the following sites: o http://www.djesys.com/vms/cdrom.html o http://www.cd-info.com/CDIC/Technology/CD-R/vms.html o http://www.faqs.org/faqs/cdrom/cd- recordable/part1/preamble.html o http://www.tmesis.com/CDrom/ o http://www.tditx.com/~odsiso/ 9-8 Files U.S. Design offers a package that includes the tools necessary to create a CD or DVD-R with either ISO-9660 or ODS-2 format, for standalone CD-R/RW, DVD-R, or DVD+R/RW drives, for recent OpenVMS versions. Details are available at: o http://www.usdesign.com/ _____________________________ 9.7.1 CD and DVD notation, terminology? CD-ROM is pre-recorded Compact Disk media, and is the original and oldest CD format. The original CD media was physically stamped, a recording process that is now largely reserved to the highest-volume media reproduction requirements. CD-R is CD Recordable, a write-once storage medium that can be read by all but the oldest of CD drives; a format which can be read and often even recorded by most CD-RW drives. CD-RW is CD ReWritable, a format which is readable by many CD drives and by most CD-R drives, and with media that can be recorded and re-recorded by CD-RW drives. CD media recording speeds are listed as multiples of 150 kilobytes per second, so a 10X drive records at 1500 kilobytes (1.5 megabytes) per second. 600 MB (70 minutes) and 700 MB (80 minutes) recording capacities are both widely available. The minutes designation is derived from the traditional audio-format recording capacity of the particular media. DVD-R/RW is the older of two common Digital Versatile Disk recording formats, and the DVD-R Recordable or DVD-RW ReWritable media can be read by many DVD drives. As with CD-R formats in older CD drives, older DVD and particularly first-generation DVD players may have problems reading this media format. DVD+R/RW is the newer of the two common Digital Versatile Disk recording formats, and the DVD+R Recordable or DVD+RW ReWritable media can be read by many DVD drives. Akin to DVD-R/RW media, older 9-9 Files and particularly first-generation DVD drives can have problems reading this media format. The DVD Plus-series drives and media tend to record faster than Minus drives, as (as of this writing) the Plus (+) drives do not require an initial media formatting pass and the Minus (-) drives do. While the appropriate Plus (+) or Minus (-) DVD raw media must be chosen for the particular DVD recorder (and DVD recording drives that are compatible with and capable of using both Plus and Minus media are available), the resulting recorded media is generally readable (playable) in all recent DVD drives and DVD players, regardless of type. (Compatibility is best within the same media-series devices of course, but be certain to verify compatibility across devices regardless of the particular device or particular recording media chosen.) Presently Plus (+) media is slightly more expensive than Minus (-), but with the prices of all CD and all DVD media continuing to consistently fall, the differences in DVD media costs are becoming irrelevent for all but the production of huge volumes of DVD media. The rated DVD recording speeds are in multiples of 1353 kilobytes per second, thus a DVD 1X drive is roughly equivalent to a CD 9X drive in I/O requirements and transfer speed. DVD drive recording speed can and does vary. DVD disk drive recording speed is limited by the rated recording speed of the media used, so the slower (and cheaper) DVD media will not record any more quickly in a faster drive. A 2.4X DVD drive loaded with 1X media will record at 1X. 9-10 Files __________________________________________________________ 9.8 What I/O transfer size limits exist in OpenVMS? The maximum transfer size is an attribute of the particular I/O device, controller and driver combination; there is no inherent limit imposed by OpenVMS (other than the fact that, today, byte counts and LBNs are generally limited to 32 bits). The maximum size of a device I/O request is limited by the value in UCB$L_MAXBCNT, which is set by the device driver based on various factors. (Also check the setting of the MAXBUF system parameter for buffered I/O transfers, and check the process quotas.) Currently, SCSI drivers limit I/O transfers to FE00(16) bytes, 65024 bytes (decimal). The reasons for this transfer size limitation are largely historical. Similarly, DSSI devices are limited to the same value, this for hardware-specific reasons. Transfers to HSC and HSJ device controllers via the CI are limited to 1,048,576 bytes. Client MSCP-served devices are limited to 65535 bytes-to help ensure that the I/O fragmentation processing happens on the client and not on the server system. Parts of the OpenVMS I/O subsystem are optimized for data transfers less than 64KB, because (obviously) most I/O operations are (substantially) less than that. OpenVMS can handle larger transfers, if the driver and the device can handle it. Also see Section 9.4, Section 9.5. __________________________________________________________ 9.9 Can I use ODBC to connect to OpenVMS database files? Yes, you can use various available third-party packages that permit remote ODBC clients to access RMS files and various commercial databases via the network. For RMS, consider acquiring one of the packages available from EasySoft, Attunity Connect (formerly known as ISG Navigator), Oracle (DB Integrator), SolutionsIQ, and Synergex. 9-11 Files For specific commercial databases (other than RMS, of course), contact the database vendor directly for assistance. __________________________________________________________ 9.10 If my disks are shown as VIOC Compatible, am I using XFC? Yes, you are using XFC caching. Disks that are using XFC caching use communication and coordination protocols that are compatible with the older VIOC caching implementation. With the initial implementation of XFC on OpenVMS, you can use the command SHOW MEMORY/CACHE to see no disks reported in full XFC mode; all disks shown will be listed in VIOC Compatable Mode. If you have the OpenVMS system parameter VCC_FLAGS set to 2 and are using OpenVMS Alpha V7.3-1 or later, or are using OpenVMS Alpha V7.3 with the VMS73_XFC V2.0 ECO kit or later, you are using XFC. 9-12 _______________________________________________________ 10 OpenVMS Programming Information __________________________________________________________ 10.1 Modular Programming, Facility Prefixes and Symbol Naming? Please first review the OpenVMS Programming Concepts Manual and the Guide to Modular Programming manuals. Both are available within the OpenVMS documentation set, and provide details of the expected norms for OpenVMS programs. o Learn about the facility prefix, and use a the appropriate prefix uniformly throughout all external symbols, all logical names, and all files located in shared directories. The prefix and the use of the dollar sign (<$>) and the underscore (<_>) help avoid collisions with other products. Use of the dollar sign is reserved to registered products. o Please consider use of tools such as the Freeware SDL package, and the GNM package. These permit you to generate include files and message documentation akin to that of OpenVMS, providing users of your product with a familiar environment. o For product installations, consider use of the PCSI installation utility, and provide a product-specific configuration DCL command procedure (usually SYS$MANAGER:prefix$CONFIG.COM) if configuration is required. o The product startup file is usually named SYS$STARTUP:prefix$STARTUP.COM, and the shutdown file (if needed) is usually SYS$STARTUP:prefix$SHUTDOWN.COM. OpenVMS provides a registry for facility prefixes and for MESSAGE message compiler codes. To request a prefix and a message facility code for a product you are reselling, send your request in a mail message addressed to product[-at-sign-]hylndr.sqp.zko.dec.com, 10-1 OpenVMS Programming Information requesting the submission form and details of the registration process. Note Please do not request facility prefixes for products that local to your business, your site, or your system. Facility prefixes and message codes and the facility registration process are intended solely for HP products and Partner Products (and yes, even OpenVMS Freeware packages) that will be distributed across multiple OpenVMS customer sites. For a list of common coding bugs, please see the remainder of this section of the FAQ and specifically Section 10.24, please also see the Ask The Wizard topic (1661), and for information on debugging an OpenVMS application, please see topic (7552). o http://www.openvms.compaq.com/wizard/ o http://www.openvms.compaq.com/wizard/wizard.zip For additional information, please see Section 3.9. __________________________________________________________ 10.2 Can I have a source code example of calling...? Please use the available SEARCH command on OpenVMS, and please remember to search the available resources, including the support databases and the newsgroup archives. Please also realize that most OpenVMS system services use similar calling sequences, meaning that an example of calling sys$getjpi can be used as an example for sys$getsyi and sys$getdvi. Students: please do not expect folks to write your homework for you. As for search resources: o SEARCH SYS$EXAMPLES:*.* target o SEARCH TCPIP$EXAMPLES:*.* target o http://askq.compaq.com/ o http://www.openvms.compaq.com/freeware/ o http://www.google.com/ 10-2 OpenVMS Programming Information OpenVMS programming documentation, including the numerous example programs found in recent versions of the OpenVMS Programming Concepts manual, is available: o http://www.openvms.compaq.com:8000/ o http://www.openvms.compaq.com/doc/ o http://www.openvms.compaq.com/commercial/ As for details of argument passing, most OpenVMS system services and RTL routines pass string arguments by descriptor. Languages which support native string data types create descriptors automatically; those which do not (eg., C) require that you set them up explicitly. For further details on using descriptors and particularly for using descriptors from C, please see Section 10.13. There is extensive information available on how to call OpenVMS system services and OpenVMS Run-Time Library routines, including examples in numerous languages. Among the best available references are: o Your language's User Manual o OpenVMS Programming Environment Manual o OpenVMS Programming Concepts Manual o OpenVMS Programming Interfaces: Calling a System Routine o OpenVMS Calling Standard In addition, if you are a subscriber to the HP Software Information Network (available to those with a software support contract), the support database contains hundreds of worked examples of calling system services and RTL routines, including the one that seems to trip up almost everyone, SMG$CREATE_MENU. Arne Vajhøj has put together a collection of OpenVMS example programs. It can be found at: o ftp://ftp.hhs.dk/pub/vms/ 10-3 OpenVMS Programming Information Additional information and examples for OpenVMS are available via: o http://www.openvms.compaq.com/wizard/ o http://www.openvms.compaq.com/wizard/wizard.zip For additional information, please see Section 3.9. and via: o http://www.openvms.compaq.com/freeware/ __________________________________________________________ 10.3 How do I get the arguments from the command line? If you're writing a program and want to accept arguments from a foreign command, you can use LIB$GET_ FOREIGN to get the command line and parse it yourself, or if you're programming in C, use the normal argc/argv method. To write an application which uses the normal DCL verb/qualifier/parameter syntax for invocation, see the description of the CLI$ routines in the OpenVMS Callable Utility Routines Reference Manual. It is possible to write an application which can be used both ways; if a DCL verb isn't used to invoke the image, the application parses the command line itself. One way to do this is to call CLI$GET_VALUE for a required parameter. If it is not present (or you get an error), call LIB$GET_FOREIGN to get the command line and do the manual parse. See also Section 8.1. __________________________________________________________ 10.4 How do I get a formatted error message in a variable? Use the SYS$PUTMSG system service with an action routine that stores the message line(s) in the variable of your choice. Be sure the action routine returns a "false" (low bit clear) function value so that SYS$PUTMSG doesn't then try to display the message (unless you want it to.) See the description of $PUTMSG in the System Services Reference Manual for an example of using an action routine. 10-4 OpenVMS Programming Information __________________________________________________________ 10.5 How do I link against SYS$SYSTEM:SYS.STB on an Alpha system? LINK/SYSEXE is the OpenVMS Alpha equivalent of linking against SYS.STB. This links against the base image: SYS$BASE_IMAGE.EXE Also see Section 10.11, particularly for pointers to the details on shareable images and shareable image creation. __________________________________________________________ 10.6 How do I do a SET DEFAULT from inside a program? The problem is that SYS$SETDDIR only changes the default directory - NOT the default disk. The default disk is determined by the logical SYS$DISK. If you want to change the default disk within a program, then call LIB$SET_LOGICAL to change the logical SYS$DISK. You will need to call both LIB$SET_LOGICAL and SYS$SETDDIR to change both default disk and the default directory! __________________________________________________________ 10.7 How do I turn my Fortran COMMON into a shareable image on Alpha? You need to add SYMBOL_VECTOR=(=PSECT) to your options file. On OpenVMS VAX all OVR/REL/GBL psects were automatically exported into the shareable image's Global Symbol Table. On OpenVMS Alpha you have to tell the linker that you want this done by means of the PSECT keyword in the SYMBOL_VECTOR options file statement. This has several advantages over OpenVMS VAX. First, you don't have to worry about the address of the psect when you try to create a new, upwardly compatible version of the shareable image. Second, you can control which psects, if any, are made visible outside the shareable image. By default, COMMON PSECTs in HP Fortran for OpenVMS Alpha (as well as most other OpenVMS Alpha compilers) are NOSHR. On VAX, the default was SHR which required you to change the attribute to NOSHR if you wanted 10-5 OpenVMS Programming Information your COMMON to be in a shareable image but not write- shared by all processes on the system. If you do want write-sharing, use: CDEC$ PSECT common-name=SHR in the Fortran source code (the CDEC$ must be begin in column 1) or a linker options file PSECT_ATTR statement to set the COMMON PSECT attribute to SHR. For further information, see the Linker manual. __________________________________________________________ 10.8 How do I convert between IEEE and VAX floating data? In OpenVMS V6.1 and later, the routine CVT$CONVERT_ FLOAT is documented in the LIB$ Run-Time Library Reference Manual, and can perform floating point conversions between any two of the following floating datatypes: VAX (F,D,G,H), little-endian IEEE (single, double, quad), big-endian IEEE (single, double, quad), CRAY and IBM System\370, etc. HP Fortran (all OpenVMS platforms) has a feature which will perform automatic conversion of unformatted data during input or output. See the HP Fortran documentation for information on "non-native data in I/O" and the CONVERT= OPEN statement keyword. There are floating-point conversion source code packages available for various platforms. For further floating-point related information, see: o http://www.hhs.dk/anonymous/pub/vms/collection/ieee.zip __________________________________________________________ 10.9 How do I get the argument count in a Fortran routine? On VAX, many programmers would use a MACRO routine which accessed the AP register of the caller to get the address of the argument list and hence the argument count. This was not guaranteed to work on VAX, but usually did. However, it doesn't work at all on OpenVMS Alpha, as there is no AP register. On Alpha systems, you must use a language's built-in function to retrieve the argument count, if any. In Fortran this is 10-6 OpenVMS Programming Information IARGCOUNT, which is also available in DEC Fortran on OpenVMS VAX. Note that omitting arguments to Fortran routines is non-standard and is unsupported. It will work in many cases - read the DEC Fortran release notes for additional information. __________________________________________________________ 10.10 How do I get a unique system ID for licensing purposes? Many software developers desire to use a unique hardware ID to "lock" a given copy of their product to a specific system. Most VAX and Alpha systems do not have a unique hardware-set "system ID" that can be used for this purpose. HP OpenVMS products do not use hardware IDs in the licensing methods, as many users consider a hardware-based licensing scheme to be negative attribute when considering software purchases. HP OpenVMS uses a software-based system called the License Management Facility (LMF). This provides for software keys (Product Authorization Keys or PAKS) which support capacity and user-based license checking. HP offers an LMF PAK Generator to CSA members-see Section 2.12. For information on licensing, please see Section 12.5. However, if a hardware-based method is required, the most common method is based on an Ethernet adaptor hardware address. Sample source code for implementing this is available at: o http://www.openvms.compaq.com/wizard/ o http://www.openvms.compaq.com/wizard/wizard.zip For additional information, please see Section 3.9. 10-7 OpenVMS Programming Information __________________________________________________________ 10.11 What is an executable, shareable, system or UWSS image? Executable code in OpenVMS typically resides in an image-an image is a file-the file extension is typically .EXE-that contains this code. Common types of images include executable images, shareable images, system images, and protected (UWSS) images. Executable images are programs that can be directly executed. These images can grant enhanced privileges, with an INSTALL of the image with /PRIVILEGE, or can grant enhanced access with the specification of a subsystem identifier on the ACL associated with the image. Shareable images contain code executed indirectly, these images are referenced from executable images and/or from other shareable images. These images can not grant enhanced privileges, even with the use of INSTALL with /PRIVILEGE or a subsystem identifier. These shareable images can be dynamically activated (a LINK that occurs at run-time) via the LIB$FIND_ IMAGE_SYMBOL run-time library (RTL) routine. (See `protected images' for information on `privileged shareable images'.) System images are intended to run directly on the VAX or Alpha hardware-these are normally used for the kernel code that comprises an operating system. Protected images-also refered to as User-Written System Services (UWSS), or as privileged shareable images-are similiar in some ways to a standard shareable images, but these images include a `change mode' handler, and execute in an `inner' processor mode (privileged mode; executive or kernel), and code executing in inner modes has implicit SETPRV privilege. Must be INSTALLed with /PROTECT. Note that inner-mode code has restrictions around calling library routines, around calling various system services, and around calling code located in other protected or shareable images. 10-8 OpenVMS Programming Information Loadable images and device drivers are images that can be used to add code into the OpenVMS kernel. Pseudo- device drivers are a particularly convenient way to add executable code, with associated driver-defined data structures, into the kernel. The pseudo-device driver includes the UCB and DDB data structures, and a calling interface with support for both privileged and unprivileged access to the driver code via sys$qio[w] calls. A cookbook approach to creating OpenVMS shareable images is available at the URL: o http://www.openvms.compaq.com/wizard/ o http://www.openvms.compaq.com/wizard/wizard.zip For additional information, please see Section 3.9. __________________________________________________________ 10.12 How do I do a file copy from a program? There are several options available for copying files from within a program. Obvious choices include using lib$spawn(), system(), sys$sndjbc() or sys$creprc() to invoke a DCL COPY command. Other common alternatives include using the callable convert routines and the BACKUP application programming interface (V7.1 and later). __________________________________________________________ 10.13 What is a descriptor? A descriptor is a data structure that describes a string or an array. Each descriptor contains information that describes the type of the data being referenced, the size of the data, and the address of the data. It also includes a description of the storage used for the data, typically static or dynamic. Descriptors are passed by reference. The following are examples of creating and using descriptors in C, with the use of the angle brackets normally expected by the C include statements deliberately altered in deference to HTML: 10-9 OpenVMS Programming Information #include {descrip.h} #include {lib$routines.h} #include {stsdef.h} int RetStat; char TxtBuf[TXTSIZ] struct dsc$descriptor StaticDsc = { 0, DSC$K_DTYPE_T, DSC$K_CLASS_S, NULL }; struct dsc$descriptor DynDsc = { 0, DSC$K_DTYPE_T, DSC$K_CLASS_D, NULL }; int DynDscLen = 255; $DESCRIPTOR( ConstDsc, "This is a string" ); /* finish setting up a static descriptor */ StaticDsc.dsc$w_length = TXTSIZ; StaticDsc.dsc$a_pointer = (void *) TxtBuf; /* finish setting up a dynamic descriptor */ RetStat = lib$sget1_dd( &DynDscLen, &DynDsc ); if ( !$VMS_STATUS_SUCCESS( RetStat ) ) return RetStat; /* release the dynamic storage */ RetStat = lib$sfree1_dd( &DynDsc ); if (!$VMS_STATUS_SUCCESS( RetStat )) return RetStat; Static descriptors reference storage entirely under application program control, and the contents of the descriptor data structure can be modified as required (by the application). OpenVMS routines do not modify the contents of a static descriptor, nor do they alter the address or length values stored in the static descriptor. (The term "static" refers to the descriptor data structure, and not necessarily to the storage referenced by the descriptor.) Dynamic descriptors reference storage under the control of the run-time library, and the contents of a dynamic descriptor data structure-once initialized- can only be modified under control of run-time library routines. The dynamic storage referenced by the dynamic descriptor is allocated and maintained by the run-time library routines. Various OpenVMS routines do alter the contents of the descriptor data structure, changing the value for the amount and the address of the storage 10-10 OpenVMS Programming Information associated with the dynamic descriptor, as required. Routines can obviously access and alter the contents of the storage referenced by the descriptor. OpenVMS languages that include support for strings or arrays are expected to use descriptors for the particular structure. Most OpenVMS languages, such as Fortran and BASIC, use descriptors entirely transparently. Some, like DEC C, require the programmer to explicitly create and maintain the descriptor. For further information on string descriptors, see the OpenVMS Programming Concepts manual, part of the OpenVMS documentation set. Fortran defaults to passing integers by reference and characters by descriptor. The following sites discuss mixing Fortran and C source code in the same application: o http://www.hhs.dk/anonymous/pub/vms/misc/FORTRAN_C_ CALL.COM o ftp://ftp.hhs.dk/pub/vms/misc/FORTRAN_C_CALL.COM __________________________________________________________ 10.14 How many bytes are in a disk block? A disk block is the minimum unit of disk storage allocation in OpenVMS. Under OpenVMS VAX and OpenVMS Alpha, the disk volume block size is consistent, with each block containing 512 bytes. The minimum disk allocation granularity actually permissible (in the ODS-2 and ODS-5 volume structures commonly used on OpenVMS) is determined on a per-volume basis, and is typically based on a combination of the total number blocks on the disk volume and the total size of the volume storage bitmap. The allocation granularity is known as the volume cluster factor- the cluster factor is the number of blocks in a disk cluster, and it is the smallest number of blocks that can be allocated on a particular disk volume. 10-11 OpenVMS Programming Information Prior to OpenVMS V7.2, the maximum permissible size of the bitmap requires larger cluster factors as volume sizes increase. Starting with V7.2, the bitmap can be larger, and cluster factors as small as one block can be used. The number of bytes in a file can be determined by multiplying the number of blocks allocated for the file times the number of bytes in a block. For sequential files (only), the FFB (XAB$W_FFB, in the File Header XAB) value can be used to find out how much of the last (XAB$L_EBK) block is used. FFB and EBK are meaningful only for sequential files, and only in a limited context-partial block allocations are not permitted. For other file formats, the EOF marker is not meaningful. Disk allocations always occur only in units of the cluster factors, which can be from one block up to (potentially) clusters of eighteen blocks or more, depending on the volume cluster factor. (OpenVMS V7.2 and later optionally provide for a cluster factor of one up to volumes of approximately 137 gigabytes.) OpenVMS assumes that the device driver and the underlying storage device will present the file system with addressable units of storage of 512 bytes in size, or the appearance of same. Various third-party CD-ROM devices, for instance, support only 2048 byte blocks, and such devices are incompatible with the standard OpenVMS device drivers. To determine the number of bytes required for a file from DCL, one option uses the f$file_attributes item EOF, multiplied by the size of a block in bytes (512). This does not account for the unused space in the last block of a sequential file, but it also does not have to differentiate sequential files from other files. 10-12 OpenVMS Programming Information __________________________________________________________ 10.15 How many bytes are in a memory page? A memory page is the minimum unit of memory allocation in OpenVMS. With OpenVMS VAX, the memory page size matches the disk block size: it is always 512 bytes. With OpenVMS Alpha, the memory page size is variable, and it can range from 8192 bytes (8 kilobytes) up to 64 kilobytes. The current system page size can be determined using the sys$getsyi or f$getsyi PAGE_SIZE item. Programs with hardcoded constants for the memory page size (or page alignment) should always assume a page size of 64 kilobytes. On OpenVMS Alpha, a 512 byte area of memory-equivilent in size to an OpenVMS VAX memory page-is refered to as a pagelet. __________________________________________________________ 10.16 How do I create a process under another username? Many server processes can operate within the context of the target user using privileges, using calls such as sys$chkpro and (more commonly in this context) sys$check_access as needed to determine if access would be permitted for the specified user within the current security model. With OpenVMS V6.2 and later, the persona system services (SYS$PERSONA_*) can be used to assume the persona of the specified user-these allow the server to operate as the specified user, in a controlled fashion. The persona services can be used as a "wrapper" around a sys$creprc process creation call, as well-this will create a seperate process entirely under the assumed persona. Information on the persona system services is included in the OpenVMS V6.2 new features documentation, and in the OpenVMS V7.1 and later system services documentation. These system services exist and are supported in OpenVMS V6.2 and later releases. 10-13 OpenVMS Programming Information Typical mechanisms for creating a process under another username include: o personna services around a sys$creprc call. See above. o via DECnet task-to-task, using explicit specification of username and password, or using a DECnet proxy. This creates a network-mode job under the target user. The network-mode job might do little more than a RUN/DETACH of an image passed in via task-to-task-task-to-task communications are fully available using strictly DCL-to-DCL processing, or using a compiled language and DCL, etc.) o SUBMIT/USER, or the username argument on the sys$sndjbc call. This creates a batch-mode job under the specified username. The batch-mode job might do little more than a RUN/DETACH of an image passed in via a parameter. o the UIC argument on the sys$creprc call. This mimics the UIC of the target user, and is certainly not the prefered mechanism for this task. o Via pseudo-terminals... There are likely a few other mechanisms around... There are various tools available from DECUS and other sources that allow various forms of user impersonation, as well. These tools will require version-dependent kernel code and enhanced privileges for some of (or all of) their operations. __________________________________________________________ 10.17 Why do lib$spawn, lib$set_symbol fail in detached processes? The processing within run-time library (RTL) calls such as lib$attach, lib$disable_ctrl, lib$do_command, lib$enable_ctrl, lib$get_symbol, lib$run_program, lib$set_symbol, lib$set_logical, and lib$spawn, is dependent on and requires the presence of a command language interpreter (CLI), such as DCL. Without a CLI present in the current process, these calls will fail 10-14 OpenVMS Programming Information with a "NOCLI, no CLI present to perform function" error. Detached processes typically do not have a CLI present. In place of lib$spawn, sys$creprc can often be used. The context of the parent process (symbols and logical names) will not be propogated into the subprocess when sys$creprc is used, though when there is no CLI present in the process this (lack of) propogation is moot. To create a detached process with a CLI, you must specify LOGINOUT as the target image as discussed elsewhere in the FAQ, or only use these calls (and any other calls requiring a CLI) from images that are running in an "interactive", "batch", or "other" mode process. Also note that the lib$spawn and the C system call will fail in a CAPTIVE login environment. The lib$spawn call can be gotten to work in this environment with the specification of the TRUSTED flag. __________________________________________________________ 10.18 Where can I obtain Bliss, and the libraries and supporting files? The Bliss language compilers and documentation are available on the OpenVMS Freeware distributions. Bliss language source code that contains the following statement: LIBRARY 'SYS$LIBRARY:STARLET.L32'; or similar requires the presence of the Bliss libraries. These libraries are created on the target system using the Bliss require files, and are built using the following Bliss commands: STARLET.L32 contains the public interfaces to OpenVMS: $ BLISS /LIBRARY=SYS$COMMON:[SYSLIB]STARLET.L32 - SYS$LIBRARY:STARLET.REQ 10-15 OpenVMS Programming Information LIB.L32 contains both the public and private interfaces to OpenVMS: $ BLISS /LIBRARY=SYS$COMMON:[SYSLIB]LIB.L32 - SYS$LIBRARY:LIB.REQ+SYS$LIBRARY:STARLET.REQ The equivilent files for Bliss64 are created with: $ BLISS/A64/LIBRARY=SYS$COMMON:[SYSLIB]LIB.L64 - SYS$LIBRARY:LIB.R64+STARLET.REQ+STARLET.R64 $ BLISS/A64/LIBRARY=SYS$COMMON:[SYSLIB]STARLET.L64 - SYS$LIBRARY:STARLET.R64 Some Bliss code may also require the OpenVMS VAX architecture flags. The following is the equivilent of the Alpha ARCH_DEFS.REQ module: ! ! This is the OpenVMS VAX version of ARCH_DEFS.REQ, and ! contains the architectural definitions for conditionally ! compiling OpenVMS Bliss sources for use on VAX systems. ! (If you should encounter compilation errors here, please ! seriously consider upgrading your Bliss compiler.) ! MACRO VAXPAGE = 1%; MACRO BIGPAGE = 0%; ! MACRO VAX = ! = 1 if compiled BLISS/VAX %BLISS(BLISS32V)%; ! = 0 if not compiled BLISS/VAX MACRO EVAX = ! = 1 if compiled BLISS/E* (Obsolete, old name) (%BLISS(BLISS32E) OR %BLISS(BLISS64E))%; ! = 0 if compiled /VAX /Inn MACRO ALPHA = ! = 1 if compiled BLISS/E* (New arch name) (%BLISS(BLISS32E) OR %BLISS(BLISS64E))%; ! = 0 if compiled /VAX /Inn MACRO IA64 = ! = 1 if compiled BLISS/I* (New arch name) (%BLISS(BLISS32I) OR %BLISS(BLISS64I))%; ! = 0 if compiled /VAX or /Ann MACRO ADDRESSBITS = %BPADDR%; ! = 32 or 64 based on compiler used Some Bliss code may require the definition files for the OpenVMS older LIBRTL routine lib$tparse, or the newer lib$table_parse call: $ BLISS /LIBRARY=SYS$COMMON:[SYSLIB]TPAMAC.L32 - SYS$LIBRARY:TPAMAC.REQ 10-16 OpenVMS Programming Information __________________________________________________________ 10.19 How can I open a file for shared access? When creating a file, it is often useful to allow other applications and utilities-such as TYPE-to share read access to the file. This permits you to examine the contents of a log file, for instance. A C source example that demonstrates how to do this is available in topic (2867) in the OpenVMS Ask The Wizard area: o http://www.openvms.compaq.com/wizard/ o http://www.openvms.compaq.com/wizard/wizard.zip For additional information, please see Section 3.9. Depending on the environment, you may need to use C calls such as fsync and fflush, and-in specific cases- the setvbuf(_IONBF) call. __________________________________________________________ 10.20 How can I have common sources for messages, constants? Use the GNM tools on the OpenVMS Freeware to have common sources for MSG (message) files and SDML (Document) documentation files. Use the DOCUMENT command to convert the SDML documentation into the necessary formats (Text, Postscript, HTML, etc). Use the MESSAGE/SDL tool (latent in OpenVMS) to create an SDL file based on the messages. Then use the SDL tool (available on the OpenVMS Freeware) to convert the SDL file into language-specific definitions. (There is also a converter around to convert SDL into SDML, if you want to get pictures of the data structures for your documentation.) __________________________________________________________ 10.21 How do I activate the OpenVMS Debugger from an application? #include {lib$routines.h} #include {ssdef.h} #include {string.h} 10-17 OpenVMS Programming Information main() { char ascic_debug_commands[128]; char *dbgcmd = "*show calls;go;exit"; strcpy( ascic_debug_commands, dbgcmd ); ascic_debug_commands[0] = (char) strlen( dbgcmd ) - 1; lib$signal(SS$_DEBUG,1,ascic_debug_commands); return 1; } __________________________________________________________ 10.22 Dealing with Endian-ness? OpenVMS on VAX, OpenVMS on Alpha and OpenVMS on Intel IA-64 platforms (as well as all Microsoft Windows implementations and platforms) all support and all use the little-endian byte ordering. Certain Alpha microprocessors and certain Intel Itanium processors can be configured to operate in big-endian and potentially in bi-endian mode. HP-UX typically operates big-endian. With little-endian byte order, the least significant byte is always the first byte; the byte at the lowest address. With big-endian byte ordering, the byte storage order in memory is dependent on the size of the data (byte, word, longword) that is being referenced. Endian-ness is a problem has been solved many times before. Some of the typical solutions include htonl/htons and ntohl/ntohs in the standard C library and the TCP/IP Services XDR (eXternal Data Representation) libraries. One of the more recently introduced network formats, and one that is seeing extensive press and marketing coverage, is XML. 10-18 OpenVMS Programming Information __________________________________________________________ 10.23 How to resolve LINK-I-DATMISCH errors? The message LINK-I-DATMISCH is informational, and indicates that the version of the specified shareable image found in the system shareable image directory does not match the version of the shareable image that was originally loaded into IMAGELIB.OLB, one of the OpenVMS libraries typically searched by the LINKER. From a privileged username, you can usually completely repair this via the following DCL command: $ LIB/REPLACE/SHARE SYS$LIBRARY:IMAGELIB.OLB SYS$SHARE:LIBRTL.EXE This command assumes that the shareable image that was found in the SYS$SHARE: area is valid and upward- compatiable, and that the image has simply replaced an older version without also updating IMAGELIB. __________________________________________________________ 10.24 Compaq C and other OpenVMS C Programming Considerations? VAX C V3.2 was released for OpenVMS VAX systems in 1991. DEC C V4.0 replaced VAX C V3.2 in 1993 as the HP C compiler for OpenVMS VAX systems. HP C is the ANSI C compiler for OpenVMS Alpha systems. VAX C predates the ANSI C standards, and has various areas that are not compliant with ANSI C requirements. HP C is an ANSI C compiler, and can also compile most VAX C code when /STANDARD=VAXC is specified. Versions of this compiler between V3.2 and V6.5 (exclusive) were known as DEC C, DIGITAL C, and Compaq C. Both compilers can be installed at the same time on the same OpenVMS VAX system, allowing a migration from VAX C to DEC C, and allowing the same DEC C code to be used on OpenVMS VAX and OpenVMS Alpha. The system manager can choose the system default C compiler when HP C is installed on a system with VAX C, and a C programmer can explicitly select the required compiler for a any particular compilation. A current "C" license PAK allows access to both VAX C and HP C on the same OpenVMS VAX system. 10-19 OpenVMS Programming Information Various HP C versions can be installed on OpenVMS VAX V5.5-2 and later. OpenVMS VAX releases such as V5.5-2 and V6.0 will require the installation of a HP C RTL kit, a kit that is included with the HP C compiler. OpenVMS VAX versions V6.1 and later do not require a seperate RTL kit, but HP C RTL ECO kits are available to resolve problems found with the C RTL on various OpenVMS releases. With HP C, for automatic resolution of the standard C library routines by the LINKER utility, use the /PREFIX qualifier, such as /PREFIX=ALL_ENTRIES. If a particular application program replaces an existing C library routine, use /PREFIX=(ALL_ENTRIES,EXCEPT=(...)). (VAX C required explicit specification of an RTL shareable image or C object library during the link.) When the /PREFIX is requested, the compiler generates a "decc$" prefix on the specified symbols. This prefix allows the LINKER to resolve the external symbols against the symbols present in the DECC$SHR library. The DECC$SHR library is included in the IMAGELIB.OLB shareable image library, and IMAGELIB is searched by default when any program (written in any language) is LINKed. Because the standard C library routine names are very likely to match application routines written in other languages, a prefix "decc$" is added to the C symbol names to assure their uniqueness; to prevent symbol naming conflicts. C programs, however, can sometimes have private libraries for various purposes, and the external routines share the same names as the library routines. (This is not recommended, but there are applications around that use this technique.) Thus the need to explicity specify whether or not the "decc$" prefix should be prepended to the external symbol names by the compiler. The qualifiers, and most (all?) with associated pragmas, that may be of interest when migrating VAX C code to HP C include: o /PREFIX=ALL_ENTRIES 10-20 OpenVMS Programming Information As mentioned above. Failure to specificy this qualifier can cause the compiler to not add the prefixes for the names of the C library routines into the references placed in the object module, which can in turn cause problems resolving the external symbols in the library when the object code is linked. o /ASSUME=WRITABLE_STRING_LITERALS Some VAX C programs erroneously write to the string literals. By default, HP C does not allow the constants to change. o /SHARE_GLOBALS Enables sharing ("shr") of globals and of extern variables. HP C sets externs as non-shareable ("noshr"), VAX C as "shr". o /EXTERN_MODE=COMMON_BLOCK VAX C assumes common block model for external linkages. o /[NO]MEMBER_ALIGNMENT Refers to the padding placed between member elements within a struct. Disabling member alignment packs the data more tightly into memory, but this packaging has performance implications, both on OpenVMS VAX and particularly on OpenVMS Alpha systems. Permit structure members to be naturally aligned whenever possible, and avoid using /NOMEMBER_ ALIGNMENT. If you need to disable member alignment, use the equivilent #pragma to designate the specific structures. The alignment of structure members normally only comes into play with specific unaligned data structures-such as the sys$creprc quota itemlist- and with data structures that are using data that was organized by a system using byte or other non-member alignment. 10-21 OpenVMS Programming Information Versions of HP C such as V6.0 include the capability to extract the contents of the standard header libraries into directories such as SYS$SYSROOT:[DECC$LIB...], and provide various logical names that can be defined to control library searches. With HP C versions such as V6.0, the default operations of the compiler match the expectations of most OpenVMS programmers, without requiring any definitions of site-specific library- related logical names. (And logical names left from older DEC C versions can sometimes cause the compiler troubles locating header files.) HP C V5.6 and later include a backport library, a mechanism by which HP C running on older OpenVMS releases can gain access to newer RTL routines added to the RTL in later OpenVMS releases-the language RTLs ship with OpenVMS itself, and not with the compilers. Example C code is available in SYS$EXAMPLES:, in DECW$EXAMPLES (when the DECwindows examples are installed), in TCPIP$SERVICES (or on older releases, UCX$EXAMPLES) when HP TCP/IP Services is installed), on the Freeware CD-ROMs, and at web sites such as o http://www.openvms.compaq.com/wizard/ o http://www.openvms.compaq.com/wizard/wizard.zip For additional information, please see Section 3.9. _____________________________ 10.24.1 Other common C issues The localtime() function and various other functions maintain the number of years since 1900 in the "struct tm" structure member tm_year. This field will contain a value of 100 in the year 2000, 101 for 2001, etc., and the yearly incrementation of this field is expected to continue. The C epoch typically uses a longword (known as time_ t) to contain the number of seconds since midnight on 1-Jan-1970. At the current rate of consumption of seconds, this longword is expected to overflow (when interpreted as a signed longword) circa 03:14:07 on 19-Jan-2038 (GMT), as this time is circa 0x7FFFFFFF 10-22 OpenVMS Programming Information seconds since the C base date. (The most common solution is to ensure that time_t is an unsigned.) If C does not correctly handle the display of the local system time, then check the UTC configuration on OpenVMS-the most common symptom of this is a skew of one hour (or whatever the local daylight savings time change might be). This skew can be caused by incorrect handling of the "is_dst" setting in the application program, or by an incorrect OpenVMS UTC configuration on the local system. (See section Section 4.4.) Floating point is prohibited in OpenVMS Alpha inner- mode (privileged) code, and in any process or other execution context that does not have floating point enabled. C programmers developing and working with OpenVMS Alpha high-IPL kernel-mode code such as device drivers will want to become familiar with the floating point processing available in the environment, and with the C compiler qualifier /INSTRUCTION_SET=[NO]FLOATING_ POINT. Device drivers and other similar kernel-mode C code must be compiled with /INSTRUCTION_SET=FLOATING_ POINT and /EXTERN_MODEL=STRICT_REFDEF. Additionally, the SYS$LIBRARY:SYS$LIB_C.TLB/LIBRARY parameter will be needed to be appended to the module specification or declared via the C compiler's include library logical name mechanism when the C compiler is resolving kernel-mode data structures and definitions. This library contains OpenVMS kernel-mode and other system declaractions, and particularly a mixture of undocumented definitions and declarations, and particularly definitions and declarations that are subject to change (and that can accordingly lead to requirements for the recompilation of application code). When sharing variables with other languages, here is some example HP C code... 10-23 OpenVMS Programming Information ... #pragma extern_model save #pragma extern_model strict_refdef extern int VMS$GL_FLAVOR; #pragma extern_model restore ... and here is some associated example Bliss code... ... EXTERNAL VMS$GL_FLAVOR, .... _____________________________ 10.24.2 Other common C++ issues HP C++ (a separate compiler from HP C) provides both symbol mangling and symbol decoration. Some of the details of working with longer symbol names and the resulting symbol name mangling in mixed language environments are listed in the shareable image cookbook, and in the C++ documentation. Symbol name decoration permits the overloading of functions (by adding characters to the external symbol for the function to indicate the function return type and the argument data types involved), and mixed- language external references can and often do need to disable this decoration via the extern "C" declaration mechanism: extern "C" { extern int ExternSymbol(void *); extern int OtherExternSymbol(void *); } Also see Section 14.7 for information on /ARCHITECTURE and /OPTIMIZE=TUNE. See Section 10.17 for information on the C system and the lib$spawn call in CAPTIVE environments. 10-24 OpenVMS Programming Information Constructs such as the order of incrementation or decrementation and the order of argument processing within an argument list are all implementation-defined. This means that C coding constructs such as: i = i++; a[i] = i++; foo( i, i++, --i); are undefined and can have (adverse) implications when porting the C code to another C compiler or to another platform. In general, any combination of ++, -, =, +=, -=, *=, etc operators that will cause the same value to be modified multiple times (between what the ANSI/ISO C standard calls "sequence points") produce undefined and implementation-specific results. Within C, the following are the "sequence points": the ";" at the end of a C statment, the ||, &&, ?:, and comma operators, and a call to a function. Note specifically that = is NOT a sequence point, and that the individual arguments contained within a function argument list can be processed from right to left, from left to right, or at any random whim. HP C for OpenVMS VAX (formerly DEC C) and VAX C do differ in the related processing. So you are looking for OpenVMS-specific definitions (include files)? UCBDEF.H, PCBDEF.H and other OpenVMS-specific definitions-these are considered part of OpenVMS and not part of the C compiler kit-are available on all recent OpenVMS Alpha releases. To reference the version-dependent symbol library sys$share:sys$lib_c.tlb, use a command similar to the following for compilation: $ CC sourcea+SYS$LIBRARY:SYS$LIB_C/LIB You can also define DECC$TEXT_LIBRARY to reference the library. You will want to review the Programming Concepts manual, and specifically take a quick look at Chapter 21. 10-25 OpenVMS Programming Information And some general background: the STARLET definitions (and thus the sys$starlet_c.tlb library) contain the symbols and the definitions that are independent of the OpenVMS version. The LIB definitions (and thus sys$lib_c) contain symbols and definitions that can be dependent on the OpenVMS version. You won't need to rebuild your code after an OpenVMS upgrade if you have included definitions from STARLET. The same cannot be said for some of the definitions in LIB-you might need to rebuild your code. (The UCB structure can and has changed from release to release, for instance.) Recent versions of C automatically search sys$starlet_ c.tlb. Explicit specification of sys$lib_c.tlb is required. Also see the Ask The Wizard website topics (2486), (3803), and (1661): o http://www.openvms.compaq.com/wizard/ o http://www.openvms.compaq.com/wizard/wizard.zip For additional information, please see Section 3.9. See Section 9.5 for information on the C off_t limitations, resolved in OpenVMS V7.3-1 and later and in ECO kits available for specific OpenVMS releases. The use of a longword for off_t restricts applications using native C I/O to file sizes of two gigabytes or less, or these applications must use native RMS or XQP calls for specific operations. __________________________________________________________ 10.25 Status of Programming Tools on OpenVMS VAX? DECthreads V7.3 and the HP C compiler (also known as Compaq C and DEC C) V6.4 are presently expected to be the last updates and the last releases of these development packages for use on OpenVMS VAX. The run- time support for both DECthreads (CMA$RTL) and for C (DECC$CRTL) will continue to be maintained, and will continue to be available on OpenVMS VAX. The VAX C V3.2 compiler is the final VAX C compiler release for OpenVMS VAX, and the VAX C Run-Time Library (VAXCRTL) will also continue to be available. 10-26 OpenVMS Programming Information New development and new features and product enhancements continue for the OpenVMS Alpha and the OpenVMS IA-64 DECthreads and C compilers. 10-27 _______________________________________________________ 11 DECwindows __________________________________________________________ 11.1 How do I let someone else display something on my workstation? On a workstation, you will want to use the "Customize" menu of the session manager utility and select "Security". When the pop-up box appears, you can select the host node, username, and tranport that will allow you to launch an application that targets the workstation display. If this does not provide you with access to the display, You need a checklist of sorts: o Make sure that you've specified the X-windows "display" correctly on the remote host. For a DECnet transport, the specification uses two colons, while the TCP/IP transport typically uses one. The X Windows server and the X Windows screen follow the host specification, delimited by a period. For example: ________________________________________________________________ Table 11-1 X Windows Display Commands _______________________________________________________ Shell_____Command______________________________________ csh # setenv DISPLAY vms.domain:0.0 sh and ksh # $ DISPLAY=vms.domain:0.0 ; export DISPLAY DCL $ SET DISPLAY/CREATE/NODE=vms.domain - ___________________/TRANSPORT=TCPIP/SERVER=server/SCREEN=screen_ o If you have verified the command is correct and things are still not working, ensure the Security settings on the OpenVMS host side will allow the 11-1 DECwindows incoming connection: Pull down the "Options" menu in the Session Manager, and select "Security...". If you do not find your host and username and transport listed among the authorized users, you will need to add an entry. o There are various transports available, including LOCAL, DECNET, LAT, and TCPIP. You must Select the transport appropriate to the incoming connection. o If the transport is "DECnet", do NOT add the double colon (::) to the node name. o If the transport is "TCPIP", "Username" must be an asterisk (*). Why? Because unlike DECnet, the TCP/IP protocol does not provide the remote username information in the incoming connection. o If the connection is "TCPIP", it is best to use a full domain name (e.g. Node.Subd.Domain). However, you may have to use the IP address itself, if your host does not have a way to resolve the address via DNS. If you have the luxury of fixed addresses (eg: you are not using DHCP), then it can be helpful to add two entries for each TCP/IP host, one that specifies the host name and one that specifies the host address. o There are various TCP/IP packages for OpenVMS, and you must use syntax appropriate to the transport installed. o If a TCP/IP connection is still not working, ensure that the transport you want has been activated for use with DECwindows. See Section 11.15 for details of configuring TCP/IP as a transport. o There is a log file created in SYS$MANAGER: which can tell you which transports are loaded, and also tell you what connect attempts were rejected, including showing what the presented credentials were. This file is SYS$MANAGER:DECW$SERVER_0_ ERROR.LOG, although the 0 could be another number if you have multiple servers on the workstation. I 11-2 DECwindows have found this file to be very useful for tracking down what needs to be put in the Session Manager Security entries. __________________________________________________________ 11.2 How do I create a display on another workstation? To create a display from an OpenVMS host to a remote X Windows display, use one of the following DCL commands: $ SET DISPLAY /CREATE /TRANSPORT=net_transport /NODE=remote_node $ SET DISPLAY /CREATE /TRANSPORT=LAT /NODE=remote_node $ SET DISPLAY /CREATE /TRANSPORT=DECnet /NODE=remote_node $ SET DISPLAY /CREATE /TRANSPORT=TCPIP /NODE=remote_node Note that LAT is typically used only for the VXT series X Windows terminals, but it can also be used from OpenVMS to OpenVMS systems on various OpenVMS releases, such as on OpenVMS Alpha V6.1 and later. For details on configuring the TCP/IP transport, see Section 11.15. If you are interested in X Windows terminals and have an older VAXstation system around, please see the EWS package on Freeware V5.0. __________________________________________________________ 11.3 How can I get the information from SHOW DISPLAY into a symbol? Use the undocumented SHOW DISPLAY/SYMBOL, and then reference the symbols DECW$DISPLAY_NODE, DECW$DISPLAY_ SCREEN, DECW$DISPLAY_SERVER and/or DECW$DISPLAY_ TRANSPORT. An example of calling the underlying (and also undocumented) sys$qio programming interface for the WSDRIVER (WSAn:) is available at: http://www.openvms.compaq.com/freeware/srh_examples/DECUS_UNDOC_CLINIC/ 11-3 DECwindows __________________________________________________________ 11.4 How do I get a log of a DECterm session? If you are working from a Decterm, you can use the AutoPrint feature. Choose the "Printer..." menu item from the "Options" menu, set the printing destination to the name of the file you want, and set "Auto Print Mode". You are now free to continue. It should be noted that all of the characters and escape sequences are captured, but if you display the resulting log file on a DECterm, then you will see exactly what was originally displayed. __________________________________________________________ 11.5 Why does the DELETE key delete forward instead of backward? This involves the Motif virtual key bindings. When a Motif application starts, it looks at the vendor string returned in the display connection information and attempts to match the string to a table of virtual bindings. You can override the default bindings in your decw$xdefaults.dat file. Here is the entry you would make to get the default VMS bindings. 11-4 DECwindows *defaultVirtualBindings:\ osfCancel : <>F11 \n\ osfLeft : <>Left \n\ osfUp : <>Up \n\ osfRight : <>Right \n\ osfDown : <>Down \n\ osfEndLine :Alt <>Right \n\ osfBeginLine :Alt <>Left \n\ osfPageUp : <>Prior \n\ osfPageDown : <>Next \n\ osfDelete :Shift <>Delete \n\ osfUndo :Alt <>Delete \n\ osfBackSpace : <>Delete \n\ osfAddMode :Shift <>F8 \n\ osfHelp : <>Help \n\ osfMenu : <>F4 \n\ osfMenuBar : <>F10 \n\ osfSelect : <>Select \n\ osfActivate : <>KP_Enter \n\ osfCopy :Shift <>DRemove \n\ osfCut : <>DRemove \n\ osfPaste : <>Insert To merge: $ xrdb :== $decw$utils:xrdb.exe $ xrdb -nocpp -merge decw$xdefaults.dat Also note that the DECW$UTILS:DECW$DEFINE_UTILS.COM procedure can be used to establish the xrdb and other symbols. Also see the DECxterm directory of Freeware V5.0 for details on connecting to OpenVMS from various UNIX platforms. __________________________________________________________ 11.6 Why is DECwindows Motif not starting? First check to see if there is a graphics device, usually a G* device. (eg: On a DEC 2000 model 300, use the command SHOW DEVICE GQ) If you do not find a graphics device: o OpenVMS has failed to find the appropriate IRQ information for an EISA graphics card (on the 11-5 DECwindows DEC 2000 series) such as the HP (Compaq) QVision, and did not autoconfigure it. Run the correct ECU (for Tru64 UNIX and OpenVMS) and reboot. This is necessary only on EISA-based systems. o You have an EISA-based system (such as the DEC 2000 model 300) and do not have a HP (Compaq) QVision video card. This EISA graphics card should have Compaq printed on it, and identifies itself as a CPQ3011 or a CPQ3111. If it is not one of these two EISA devices, then OpenVMS does not support it. (There are no other supported EISA graphics controllers, and EISA graphics are normally used with DECwindows only on the DEC 2000 series systems.) o You have a PCI-based system, and do not have a supported graphics controller-examples of supported controllers include the following: o PowerStorm 3D30 o PowerStorm 4D20 o PowerStorm 300 o PowerStorm 350 o ELSA GLoria Synergy o 3DLabs Oxygen VX1 See Section 5.15 for further information on some of these graphics controllers. o You have booted the system minimally, or have otherwise disabled the device autoconfiguration process. If there is a G* graphics device present: o There may have been a severe error in the DECwindows startup. Type the contents of SYS$MANAGER:DECW$SERVER_0_ERROR.LOG for any information on errors starting the server. 11-6 ---------------------------- #include ----------------------------- For additional, please see the OpenVMS FAQ -- www.hp.com/go/openvms/faq --------------------------- pure personal opinion --------------------------- Hoff (Stephen) Hoffman OpenVMS Engineering hoff[at]hp.com