UML Sequence Diagram

This purchase order processing UML activity diagram was created on the base of activity diagram from the software architecture documentation wiki of the Software Engineering Institute (SEI) of Carnegie Mellon University (CMU).
[wiki.sei.cmu.edu/ sad/ index.php/ Image:PurchaseOrderActivityDiagram.png]
"A purchase order (PO) is a commercial document and first official offer issued by a buyer to a seller, indicating types, quantities, and agreed prices for products or services. Acceptance of a purchase order by a seller forms a contract between the buyer and seller, so no contract exists until the purchase order is accepted. It is used to control the purchasing of products and services from external suppliers.
Creating a purchase order is typically the first step of the purchase to pay process in an ERP system." [Purchase order. Wikipedia]
This purchase order processing UML activity diagram example was created using the ConceptDraw PRO diagramming and vector drawing software extended with the ATM UML Diagrams solution from the Software Development area of ConceptDraw Solution Park.

The vector stencils library "Bank UML activity diagram" contains 32 shapes of UML activity diagram.
Use it for object-oriented modeling of your bank information system.
"Activity diagrams are constructed from a limited number of shapes, connected with arrows. The most important shape types:
* rounded rectangles represent actions;
* diamonds represent decisions;
* bars represent the start (split) or end (join) of concurrent activities;
* a black circle represents the start (initial state) of the workflow;
* an encircled black circle represents the end (final state).
Arrows run from the start towards the end and represent the order in which activities happen.
Activity diagrams may be regarded as a form of flowchart. Typical flowchart techniques lack constructs for expressing concurrency. However, the join and split symbols in activity diagrams only resolve this for simple cases; the meaning of the model is not clear when they are arbitrarily combined with decisions or loops.
While in UML 1.x, activity diagrams were a specialized form of state diagrams, in UML 2.x, the activity diagrams were reformalized to be based on Petri net-like semantics, increasing the scope of situations that can be modeled using activity diagrams. These changes cause many UML 1.x activity diagrams to be interpreted differently in UML 2.x." [Activity diagram. Wikipedia]
This example of UML activity diagram symbols for the ConceptDraw PRO diagramming and vector drawing software is included in the ATM UML Diagrams solution from the Software Development area of ConceptDraw Solution Park.