The hottest view of digital workflow from JDF spec

JDF (job definition format) launched by CIP4 organization is developed on the basis of CIP3 PPF (print production format) and adobe pjtf (portable job ticket format). It is the key technology to realize the digital printing workflow. Recently, the author browsed the technical specifications of version 1.3 of JDF newly published by CIP4 organization, preliminarily learned the operation structure of JDF, the components of JDF workflow and JDF workflow, and had a preliminary understanding of this, and also deepened the understanding of digital workflow. It is written here for reference. Maybe my understanding is more one-sided. I hope to throw a brick to attract jade for further discussion

1. JDF structure

a job is a complete JDF project. Each job is organized in a tree structure, containing all the information required to complete the expected project. Information is collected to nodes, and each node represents an expected job to be executed. Therefore, JDF jobs are composed of a set of nodes that describe the steps required to make the final product. These nodes, in addition to being connected to the input, not only stipulate the basic requirements of food contact materials input and output, but also are incorporated into the hierarchical tree structure (as shown in Figure 1)

in order to better understand the workflow of JDF, here we take the production of the whole book as an example to illustrate the meaning of each digital node in the JDF structure diagram (as shown in Table 1)

in the JDF structure, the top nodes (such as 1, 2 and 3) represent the intention of the product to be produced, that is, to describe the final product required and the composition of the product. In this example of making a book, the assignment has two sub elements: cover and content. Each node must have clear requirements, so nodes 2 and 3 must be further described. The content page includes color pages and black-and-white pages. Due to different processing methods for making different pages, high-density polyethylene outer protective pipe polyurethane foam prefabricated directly buried insulation pipe cj/t114 ⑵ 000 type, which requires further branches of tree structure. As a tree branch, each child node defines an element of a product, which has a set of unique characteristics, so the information contained in the node needs to be further described. For example, different media, different sizes or different color requirements

it can be seen that the workflow of JDF is determined by the structure of JDF. The more complex the structure is, the stronger the function of its workflow is

II. Composition of JDF workflow

the main components of JDF workflow are composed of four parts, which are commonly referred to as agents, controllers, devices and machines. These four main parts are used to generate, modify, determine the route, explain and perform the task that the puncture device of JDF electronic universal experimental machine should keep its original sharpness intact. At the same time, MIS (Management Information System) manages the workflow generated by these components

(1) machine

machine refers to the part designed to execute the process in the workflow system, which is usually called physical equipment. Such as a printing machine or a binding machine, it also includes the software part for running a specific machine. Workstations processed by computers, whether through automatic file processing or manual control, are still considered machines if they are not connected to the JDF interface

(2) equipment

the equipment must be a machine that can execute the JDF node, start and really run. The device must support JMF (job management format) information in order to interact dynamically with the controller. In the workflow system, the most basic function of the device is to execute the information specified by the media and the route specified by the controller

(3) media

anything used to form JDF can be considered as a media. Media is responsible for describing JDF in JDF workflow. It can generate a JDF job, add nodes and modify nodes in existing jobs. The media can be software programs, automated tools, or text programs

(4) the controller

medium is used to generate and modify JDF information, and the controller is used to determine the route of relevant equipment. The minimum requirement of the controller is to be able to control the operation of at least one equipment, or at least to control the sub controller that enables one equipment to start and operate. In some cases, a controller like a pyramid hierarchy can be established to control a series of low-level controllers with the help of the controller at the top of the pyramid. However, the bottom level controller of the pyramid must have the ability of equipment. Therefore, the controller must be able to work together with other controllers

in order to communicate with each other and devices, the controller must support the exchange protocol of JDF files and JMF. The controller can also determine process planning and scheduling data, such as process time and planned production volume

in addition, the system that monitors the relationship between various parts of a workflow is called MIS management information system. MIS is a macro controller, which is responsible for indicating and monitoring the implementation of all aspects of the workflow. Therefore, it must keep in touch with the actual production equipment, which can be completed by using JMF information in real time, or using the inspection records in JDF

in order to make MIS effectively communicate with other workflow components, JDF provides important information services in the form of JMF. Here, a variety of information types can be used, ranging from simple one-way communication to inquiry, and even commands. System designers have great flexibility in how to choose and use information structures

III. JDF workflow

in the digital workflow system, the whole printing operation is an interconnected workflow in the important links such as prepress, printing, post printing, with the help of JDF, from the submission of the operation to rip, film output, plate making, inking, cutting, binding, and then to sending. This is determined by the structure of JDF. JDF uses a structure to define the processes needed to produce each expected result and identify the elements needed to complete these processes. All processes are decomposed into many nodes, and the whole job is represented by a tree structure with these nodes. All the nodes together represent the required printed matter

each independent node of JDF is defined according to the form of input and output. The input node is composed of the resources it uses and the parameters that control it. For example, to make the cover of a booklet, the process parameters of node input description should include trapping, rip, image layout, etc. the output of the node should be the post rip image, but the post rip image will become the input resource to describe the next node

if a node does not represent the final product, the resources generated by a node may be modified or consumed by subsequent nodes (such as ink, paper, etc. of consumables). In the printing process, the output product generated after the completion of a certain process will become the input product of the next printing process, and so on until the end of all processes

it is particularly emphasized that JDF operation, like any printing operation, is defined according to the original intention of the final product. However, JDF job is different from ordinary printing job. The difference is that JDF allows the whole job to be pre-defined from pre press to post press, and all resources and processes required in the whole print production can be identified and arranged on the node. Therefore, a complete printing job is completed by executing a series of nodes of the whole job in the JDF workflow, so as to realize the digital workflow of pre press, printing, post press, sending and other links

IV. understanding of digital workflow

through the preliminary analysis of JDF specification, the author has a certain understanding of digital workflow

1. digital workflow is a powerful system engineering

for digital workflow, because its emergence and use are relatively late, manufacturers and users have different understanding of it. Manufacturers often emphasize the importance of digital workflow, while users think it is dispensable. From the perspective of JDF, digital workflow itself is not a commodity, let alone a single product. Therefore, it is impossible for any manufacturer to produce a complete set of marketable workflow products

jdf in the digital workflow, no matter how many departments are involved in the whole operation and what process steps and equipment are used, they are defined in the form of "nodes". By implementing a series of printing processes represented by "nodes", we can not only organically connect production management and management information system, but also integrate all printing links such as prepress, printing, post printing and sending, so that all information, such as production plan, work progress, real-time tracking of operations and equipment, can be shared by the whole system. Therefore, the fully digital workflow connected through JDF "nodes" is a powerful system engineering (as shown in Figure 2). Its control of the whole printing process is highly integrated and automated, and plays an important role in improving printing quality and production efficiency

2. Necessary conditions for realizing digital workflow

workflow is an information technology that uses electronic systems to manage and monitor the production process. In the printing industry, digital workflow is a process that realizes the automation and high integration of printing products with digital production control information. In order to realize a fully digital workflow, two conditions must be met

(1) the degree of digitalization continues to improve

digital workflow is developed on the basis of information digitalization, so it is required to continuously improve the degree of digitalization in the process of printing production. We should adopt digital documents, digital proofing, digital printing equipment and computer to manage the data flow of production and office systems, so that the whole process flow can realize data, standardization, standardization, networking management and ICC Color Management and other new technologies. This condition is a prerequisite for printing enterprises to realize digital process

(2) it has a set of compatible and powerful industrial standards

in this regard, CIP4 organization has formulated relevant standards for the printing industry, such as PDF, JDF, etc. The key is how to use these industrial standards to develop a workflow that meets the requirements of printing enterprises. At present, many manufacturers have developed relevant new products, such as Agfa's: apogee x, Heidelberg's meta dimension, Kodak's PRINERGY, screen's trueflow 3, Peking University Founder's Changliu, etc., which provide a good solution for the printing digital workflow (1) engineering plastics

in foreign countries, the application of full digital workflow system based on JDF specification has begun to popularize. In China, different printing enterprises