The ttchmod ToolTalk client (see Listing 5) is much simpler than the ttchmodd ToolTalk server. The client opens a ToolTalk process and locates the session. The TtChmod process-type message request consists of the Chmod operation with the file name and mode input arguments. It is sent to the ToolTalk Service to be brokered to a registered server application accepting the ptype pattern. However, note that this example omits error checking and garbage collection with tt_mark and tt_release.
The Desktop Action database in CDE describes methods and objects for applications to act upon. CDE's Desktop Service can describe an action like DtChmod, shown in Listing 6, that can be forwarded through the ToolTalk Service to ttchmodd. If the action does not receive the appropriate arguments, then the Desktop can prompt the user, as shown in Figure 3.
The relationship of the Desktop Action definitions to CDE methods is similar to the relationship of ptype definitions to ToolTalk processes. For an example of Desktop actions and data types, run dttypes at the command line to dump the database to the screen.
The APIs of the Desktop Service can invoke actions registered in the Desktop database either from a C program or from a dtksh script, as shown in Listing 7. The dtchmod.ds dtksh script prompts the user, with the message dialogue, as shown in Figure 4, to confirm with the user before requesting changes to the file's mode.
In addition to calling Desktop actions from C programs and dtksh shell scripts, users can initiate requests from the command line, as shown here:
dtaction DtChmod /etc/motd 644
If the appropriate arguments are given, then the action is forwarded to ToolTalk; otherwise, the user is first queried, as shown in Figure 3.
We have seen how the ttchmodd service registered with ToolTalk can receive messages matching the TtChmod ptype pattern from ToolTalk clients, from Desktop clients written in either C or dtksh, from the command line and from double clicking on file object icons. These examples demonstrate how client and server applications can be developed independently, mixed and matched, and upgraded separately through plug-and-play. A ToolTalk-enabled application service registered with its ptype definition can be developed without specific knowledge of its counterpart.
CDE defines a message dictionary of desktop-specific ToolTalk process types, operations and arguments as seen from viewing the database. Others, such as Computer-Aided Design (CAD) and Electronic Design Automation (EDA) services have developed supplemental dictionaries. You can use existing ptypes or define your own, but the important point to know is how to register the process-type identifier, operation and arguments.
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
Free to Linux Journal readers.Register Now!
- SUSE LLC's SUSE Manager
- My +1 Sword of Productivity
- Murat Yener and Onur Dundar's Expert Android Studio (Wrox)
- Managing Linux Using Puppet
- Non-Linux FOSS: Caffeine!
- Doing for User Space What We Did for Kernel Space
- SuperTuxKart 0.9.2 Released
- Parsing an RSS News Feed with a Bash Script
- Google's SwiftShader Released
- Rogue Wave Software's Zend Server
With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide