Take today's topics in reality. I haven't written a letter for a long time, I am going to write a letter to my home, so I will write a letter next to the table. After a few days of brewing concept, I will complete it. After I finished writing, I bought an envelope and a few stamps, putting the information of the recipient and the address, sender, sender address, zip code, and then I will send it to the post office. Letter. After a week, I came to the phone to say I received a letter. So my letter has finally completed the journey through many ways.
In the above description, we can get the following concept: letters, envelope information, post office, me, and my home. According to the envelope information I offer, the post office sent the letter to my house through some way. This is a brief description of the entire time. The delivery letter in the post office uses himself to transfer according to the administrative division and the transfer path established.
Say that we look back, the responsibility of the workflow engine, the user provides the process definition XPDL (process delivery information, and each link information of the process processing), process service processing information, process participant information, workflow engine needs to do Simply put, just accept user instructions, including the establishment process, distribution work tasks, etc., then the engine distributes work items to the specified participant, and the specific business operations that each participant must perform is the process is not perceived. Just know that those people need to do things, but doing the business don't know (just like the post office doesn't know my letter content, he sent the letter to my house to complete the task, my family knows the specific letter content). Of course, the post office will give us a receipt when we send a letter to query the letter status. This receipt is that I and the post office can be used. According to the number, I can query the letter status, and the post office can also query the delivery of the letter. However, in the workflow engine, this number becomes two, one to the user, the event encoding provided by the user under the record, one is the encoding information of the logo used inside the engine. This allows users to check the current event processing status to the engine at any time.
The focus of this class is that we must separate the engines and application system developers should separate, so that the engine avoids unnecessary coupling, increasing the adaptability of the engine. At the same time, it is abstracted the three major data sets in the engine:
(1) Process definition data XPDL
(2) Process period data runtime
(3) Organization model adopted by the process
In addition, the engine also provides some additional features, such as calling an external application interface (when sending a message), the engine will call these external applications appropriately.
Of course, from the postal system ratio can be more than many other workflow engine interface. Due to this reasons, I don't talk much.
