How to draw a business architecture diagram — 3. Breakdown diagram

Decomposition diagram: It is the orderly separation of research objects or the orderly collection of fine-grained elements.
The decomposition diagram is the second diagram of the three views of the business architecture. It has two purposes: one is top-down "decomposition", and the other is bottom-up "collection". However, whether it is decomposition or summary, it is drawn from top to bottom, so these types of diagrams are collectively referred to as "exploded diagrams."
The decomposition diagram can give a more detailed affiliation between the internal elements of the research object, which is a fine-grained expression. It is usually used for detailed design in architecture diagrams. Drawing an exploded diagram requires a deep understanding of the research object.
The decomposition diagram is a "static expression" of the research elements (comparatively speaking, the flowchart is a "dynamic expression", see the next article for details).

1. Model interpretation

Take the income and expenditure function of an enterprise as an example to illustrate the expression method of the following decomposition diagram model

1. Decomposition: From top to bottom, the coarse-grained elements are decomposed step by step from "① → ② → ③" down according to a certain relationship.
2. Layering: It can be seen that on the same exploded diagram, there are three layers, namely: ①layer, ②layer, and ③layer.
3. Dependent: You can see the relationship between the main item and the child item. Each lower level is a child item relative to the upper level. ③ is a child item of ②, and ② is a child item of ①.
4. Partition: In addition to the performance of "layering" from the decomposition diagram, it can also be seen that the performance of "partition", ②, ③, ④, ⑤ are all partitions.
5. Relationship: The association line indicates the relationship between the upper and lower levels. The association line with arrows is not used here. If you want to emphasize the direction of decomposition, you can use the association line with arrows.
6. Granularity: The granularity of the elements in each layer (①layer, ②layer, ③layer) must be consistent.

2. Model drawing method (take "downward decomposition" as an example)

First of all, make sure that the results of your analysis are applicable using "exploded diagrams". The order of drawing is: layering, division, function, the order of drawing is as follows,

1. Layering: First determine the layering (horizontal)
   □The first layer is the "object", □The second layer is the split of the first layer (2.1 and 2.2);
   □The third layer is the split of the second layer (3.1 .1/3.1.2; 3.2.1～3.2.1);

2. Partition: then determine the partition (horizontal)
   □The composition of partition ④: 2.1; 3.1.1 and 3.1.2;
   □The composition of partition ⑤: 2.2; 3.2.1, 3.2.2 and 3.2.3;
   if there are more below The previous steps are repeated. The exploded view has a wide range of uses and various forms, including both vertical and horizontal layouts.

3. Applicable scenarios

Any object that can be split to the next level can draw its exploded view. such as

1. Function: System → Subsystem → Module → Function;
2. Organization: Industry → Enterprise → Department → Position → Role;
3. Work: business operation → finance → budget → reimbursement → payment;
4. Items: material classification → equipment classification → fixed assets; etc.

For more information, please refer to the book "Dahua Software Engineering—Requirements Analysis and Software Design".