Analysis of print mode of virtual application and cloud computing

Printing is essential for many applications. Relative to cloud data, cloud computing virtual world, print is actually physical output, always have to get the hand to complete. Whether a virtual application can be printed or not is related to the integrity of the virtual application. In order to get the service-side virtual applications to print exactly as the local application of the same feeling, need to ensure that both commonality and efficiency.

At present, remote access and virtual application products are mainly used in the following printing mode:

1. Map printing. The basic principle is to map the client printer to the server, select the mapped printer output when printing, the network will print machine code to the client, the client directly to send the printer.

There are a number of drawbacks to this pattern: first, you need to install a printer driver that matches the terminal printer on the server, how many printers the client has, and how many print drivers the service may have to install. In addition, because the server's printing is maintained at the hardware level, the operating system does not do session isolation, the end user can see, and select "Someone else's" printer, will occur the wrong printer's "channeling" event. More lethal, according to the different printing drive, the output is PostScript or ESC, PCL and other printing machine code, network transfer data is very large, not only affect the printing speed, and because the server operating system does not print pool buffer, when the printing volume is large, will serve "suffocated" phenomenon.

2. Virtual printing. The principle is to convert the printout to the standard format on the server side, and then decode and print it to the client. The current common format is Adobe PDF, Ms Xps, the former conversion rate and compression rate is better.

Regardless of the server load or network transmission, the virtual print mode is undoubtedly better than the mapping of the printing mode has inherent advantages, but how to ensure the stability of the system operation, and to give users a better operating experience, the product of the software work still has a lot of space.

This paper takes the remote access management software of "Benefit and VA virtual Application Management platform" as an example to analyze the realization way of virtual printing and the design details of the mature software PRODUCT.

Software Name: VA virtual Application Management Platform software version: 5.1.4.7179

Applicable platform: Server _win2003 servers, Win2003 server 64Bit, Win2008 server (SP1/SP2), Win2008 64Bit Serve, Win2008 Serve, R2, Client _ Full range of Windows systems

Product website: http://www.eheva.com Trial Download: Http://eheva.com/Va/Download/VAsetup.rar

Benefits and VA Adopt virtual printing mode, the print task is done by the service side "common print driver" and the client "intelligent printing".

On the server side, VA automatically installs a generic virtual print driver VA Universal Printer, setting up a virtual printer vaprinter. VA Universal Virtual Print driver complete: A, print direct output to PDF (all printing using the same virtual printer); B, automatic identification of the print source session, to ensure the session isolation between printing; C, automatic network flow balance to the terminal (to prevent the network from being blocked by the print task, to ensure higher priority operation and display instructions unblocked);D, session queue buffer, first hit first get (guarantee print order); E, the server can record logs (even traceable to the original print content).

To accommodate different resources and applications, you can also use the VA console to set the following settings on the server:

Print conversion Process Control

According to the scale of system resources and the nature of application software, the priority function of print background conversion is set in VA console, which is helpful to ensure the stability of server system. If you choose a higher conversion mode, when the server resources are busy, the priority of the printing process, to improve printing efficiency.

Predefined paper Type

VA Universal Virtual Print driver supports a wide range of printer paper types, including a variety of conventional paper types, such as A4, B5, and so on, also supports a variety of unconventional custom paper, VA console once defined a custom paper type, you do not need to do two times on the client definition, will automatically pass the paper parameter to the client, and automatically create the custom paper type on the client computer.

Service-side print efficiency test

After the actual test 200 pages of virtual printing pressure test, the service end of about 25 seconds to complete the printing. Detailed observation of the printing process, found that the 200-page test page from the server to the client to compress to 644K files, due to high compression rate, transmission speed, in the client physical printer printing efficiency is naturally high. For conventional enterprise Information application, this printing efficiency will have a good experience.

VA client program "AR application Executor" in the local characteristics of the configuration, the print mode has the above mapped print and virtual printing mode choice, "Use virtual printing" for its default settings:

We know that the PDF document printing is not difficult, but different documents, reports and even Bill printing, which requires easy operation, but also to meet the needs of various applications changes, how to deal with this contradiction, the software designers is a test. In the AR printing function we see a novel design, through a "Smart Print dialog box", the user only need to make simple settings, they can achieve a variety of different printing needs. Without special requirements, all options are satisfied with a carefully set default value.

In the Smart Print dialog box, you can preview in real time, print range, zoom rotation, multi-page typesetting and other dynamic adjustment operations.

Paper-Type "server priority/Client First" option, this means that when the printed document paper type is not the same as the printer's paper type, the paper type print output that is set by the document or printer is selected, and if the printer does not support document paper type, the paper type is printed with the printer setting, even if the service side is selected first. This kind of intelligent design fully guarantees the actual effect of printing in the default state.

Intelligent in the design, in addition to paper-type matching, but also includes automatic printing countdown setup options:

Start automatically when document paper and printer paper do not change: If the application prints the required paper type and the paper type of the client printer does not change, start the countdown from the set time (for example, 10 seconds, or 0 seconds), and if the print parameter is not resized, the Settings window will be automatically closed to start printing; Do not countdown, you must click the "Print" button to print.

Always start automatically, regardless of whether or not the document paper or printer paper has changed: Always countdown to print automatically.

Do not start automatically, manually start: Each time you must click the "Print" button before you print.

Through these three kinds of automatic printing mode choice, that can minimize the operation workload, can also take into account the special circumstances of human participation needs, and set flexible and convenient.

Through the above analysis and testing, we see benefits and VA This product uses the reasonable technical route, solves the printing drive, the session isolation, the network transmission and so on, and takes into account the printing efficiency and the individuality demand balance aspect to give the sufficient attention, Through the meticulous function design realizes the different application and the user to the remote virtual printing localization simulation request and the operation experience, is the present virtual application printing mode complete solution.