Editor Manual. Gruppe 3 Christoph Höger, Jonas Hurrelmann, Peggy Sylopp, Sebastian Szczepanski

Transcription

1 Editor Manual Gruppe 3 Christoph Höger, Jonas Hurrelmann, Peggy Sylopp, Sebastian Szczepanski September 5, 2007

2 Contents 1 Introduction Motivation Formal specification Petri Nets Net transformation rules Algebraic higher-order networks Implementation details Installation Example Workflow Philosophers in library Command reference Basic features Copy & Paste Undo / Redo Direct Edit Properties View ObjectNet editor Palette Additional features GraphLayout Fire Transition Rule Editor Palette Creating and deleting a nac Copy Graphs High-Level Net editor Palette Transitions

3 Chapter 1 Introduction 1.1. Motivation The visual editor for RONs was implemented due the project Visual Languages at the Technical University Berlin in RONs are so called Reconfigureable Object Nets, which allow the visual modelling of concurrent workflows. One of the basic motivations is derived from the (Formal modeling and analysis of flexible processes in mobile ad-hoc networks) project, supported by the DFG (Deutsche Forschungsgemeinschaft). The MANETs (Mobile Ad-hoc Networks) are used in a network of mobile devices, where team members communicate with one another via wireless links without relying on an underlying infrastructure. Team members execute a set of activities modeled as workflow. This can be used in emergency scenarios, such as the documentation after earthquakes on archaelogical sites. The MANETs topology both influences and is influenced by the workflow. The workflow modifications are modeled as required by transformations of the topology. The goal is to adequately specify techniques for multi-level modeling of workflows in those MANETs. On proposed solution, is to apply algebraic approaches based on algebraic higher-order nets (AHON) with Petri nets, graphs and rules as tokens, while the AHON coordinates the workflow execution and rule application. Additionally a suitable algebra has to be defined for the AHON, e.g. for calculation of applicability of rules and resulting nets. In contrast RONs are a subset of AHON with fixed transition types and such do not have a formal semantic given by a signature and algebra. Such RONs can have, like Petri nets, an visual represenation and thus allow the flexible and intuitive modelling of workflows that can be described by the given set of transition types. The aim of the project was, to implement an visual appealing and usable editor to easily create RONs. This manual will guide you trough the basic usage of the editor and give you a short introduction to the mathematical background needed to formalize RONs and Petri nets Formal specification It is suggested that you read this section, if you have no prior knowledge of Petri nets or RONs as we assume you understood the basic concepts throughout the rest of the manual. We may add, that you can also model RONs without a deep understanding of the grounding category theory. 2

4 1.2.1 Petri Nets A Petri net (also known as a place/transition net or P/T net) is one of several mathematical representations of discrete distributed systems. As a modeling language, it graphically depicts the structure of a distributed system as a directed bipartite graph with annotations. As such, a Petri net has place nodes, transition nodes, and directed arcs connecting places with transitions. Petri nets were invented in 1962 by Carl Adam Petri in his Ph.D thesis. A Petri net consists of places, transitions, and directed arcs. Arcs run between places and transitions - not between places and places or transitions and transitions. The places from which an arc runs to a transition are called the input places of the transition; the places to which arcs run from a transition are called the output places of the transition. Places may contain any number of tokens. A distribution of tokens over the places of a net is called a marking. Transitions act on input tokens by a process known as firing. A transition is enabled if it can fire, i.e., there are tokens in every input place. When a transition fires, it consumes the tokens from its input places, performs some processing task, and places a specified number of tokens into each of its output places. It does this atomically, i.e. in one single non-pre-emptible step. Execution of Petri nets is nondeterministic. This means two things: 1. multiple transitions can be enabled at the same time, any one of which can fire 2. none are required to fire - they fire at will, between time 0 and infinity, or not at all (i.e. it is totally possible that nothing fires at all). Since firing is nondeterministic, Petri nets are well suited for modeling the concurrent behavior of distributed systems. 1 We can also define Petri nets algebraically: Let N = (P, T, A, M 0, W, C) be a 6-tuple, where P is a non-empty set of places T is a non-empty set of transitions A is the set of arcs A (P T ) (T P ) M 0 : P N is the initial marking, so the count of tokens for every place W : A N + are the arc weights, so the costs for firing the transition C : P N + { } are the capacities for the places which can possibly be infinite. We assume that a capacity of 0 is equivalent to a capacity of. Further we define pre(t) = {p P (p, t) A} and post(t) = {p P (t, p) A}. Thus we can decide if an transition t T can fire if for a marking M n to the time n the following holds: 1. p pre(t) : M n (p) W (p, t) 2. p pre(t) \ post(t) : C(p) M n (p) + W (t, p) 3. p pre(t) post(t) : C(p) M n (p) W (p, t) + W (t, p) 1 Please also refer to where large parts of this section were derived from. 3

5 When firing a transition t T, it follows that for all p P : M n (p) W (p, t) p pre(t) M n+1 (p) = M n (p) + W (t, p) p post(t) M n (p) otherwise Example For illustration we consider the Consumer-Producer-Net: It shows the behavior that a consumer may only get a product from the producer if it is ready and the producer stops production until the consumer consumed the product Net transformation rules We now consider graph rewriting rules which are used to perform the transformation of petri nets. We follow closely the double-pushout approach (DPO): From the perspective of the DPO approach a graph rewriting rule is a pair of morphisms in the category of graphs with total graph morphisms as arrows: r = (L K R) where K L is injective. The graphs L and R are respectively called the left-hand side (LHS) and the right-hand side (RHS) of the rule. The graph K is called invariant or sometimes the gluing graph. A rewriting step or application of a rule r to a host graph G is defined by two pushout diagrams both originating in the same morphism m: L K R G D G (this is where the name double-pushout comes from). Another graph morphism m : L G models an occurrence of L in G and is called a match. Practical understanding of this is that L is a subgraph that is matched from G, and after a match is found, L is replaced with R in host graph G where K serves as some kind of interface. 2 We can now extend this by adding one ore more negative application conditions (NAC) by setting r = (N i L K R). This means, for a match m : L G satisfy the NAC, there is no injective morphism x : N i G such that x n = m with n : L N i ( morphism from left side into the NAC). Practically this means, we define a matching from the LHS to the RHS and all the NACs. We restrict all the matchings to be injective, to make things easier and unique. As we have a bipartite graph G = (N,E), we also restrict the morphisms f to be type-safe, hence type(f (n)) = type(n) n N and we force the source and target to be compatible such that sour ce(f (e)) = f (sour ce(e)) and tar get(f (e)) = f (tar get(e)) e E. Finally we also need to ensure that f P pre 1 = pre 2 f T and f P post 1 = post 2 f T always holds to make the morphisms valid. This means, that pre and post have to be consistent, such that the total weights of the incoming and outgoing arcs are invariant under the morphism. 2 Please also refer to where large parts of this section were derived from. 4

6 1.2.3 Algebraic higher-order networks There are several extensions to the classical Petri nets, for example colored Petri nets, where tokens are colored to make them distinguishable. We are using a subclass of Algebraic higher-oder networks (AHON), as an extension to the classical Petri nets. The token of AHONs are either object nets (in the sense of petri nets) or rules that define the transformation of object nets. The basic structure is again based on places and transitions that are connected via directed arcs. In general an AHON allows you to define an signature and algebra to apply a wide range of operations on higher-order transitions and arcs. As we only consider RONs, we will now define the subset of transitions and places that are allowed. First off a high-level places are typed either as NET or RULE and thus can either hold object nets or rules and do not have a capacity. Also the arcs have no weights in contrast to our regular Petri nets. There are four types of high-level transition: 1. STANDARD: Moves object nets and rules through the high-level net (this implies delete, copy, move and union operation) 2. FIRE: Fires a transition in an object net on a high-level place 3. APPLYRULE: Apply an network transformation rule on a object net 4. SPLIT: Split an object net on a high-level token into it s connected components So in detail this means for a transition to be valid and active: STANDARD Incoming: At most one RULE place and arbitrary NET places Outgoing: Arbitrary NET (RULE) places, if there is at least an incoming NET (RULE) place. Active: At least one token on each incoming place Action: On all outgoing NET places put the disjoint union of all the uppermost object nets tokens taken from the incoming NET places. On all outgoing RULE places, put the uppermost rule token that was taken from the incoming RULE place. Remove all tokens add to the outgoing places from the incoming places. FIRE Incoming: One and only one NET places Outgoing: One and only one NET places Active: At least one token is on the incoming place and the low-level object net as at least on transition that can fire Action: Fire a transition of the uppermost token of the incoming place and put the token on the outgoing place (if there is more than one transition that can fire in the object net, ask the user) 5

7 (a) Copy (b) Union (c) Move (d) Delete Figure 1.1: Examples for STANDARD transitions Figure 1.2: Example for a FIRE transition APPLYRULE Incoming: Exactly one RULE place and at least one NET place Outgoing: Arbitrary NET and RULE places. Active: At least one token on each incoming place and there is at least one match in the uppermost rule. Action: Remove the uppermost token from every incoming NET place and the uppermost token from every incoming RULE place. Apply the rule token taken to the union of all taken object net token. Put the result on every NET outgoing place and put the rule token to all outgoing RULE places. SPLIT Incoming: Exactly one NET place and no RULE place Outgoing: Exactly one NET place and no RULE place 6

8 Figure 1.3: Example for a APPLYRULE transition Figure 1.4: Example for a SPLIT transition Active: At least one token on the incoming place Action: Take the uppermost token from the incoming place and split this object net in all connected components and create for each connected component a new token. Put each of the new tokens into the outgoing place. 7

9 1.3. Implementation details To give you an basic understanding on how the RON was implemented, consider the (partial) model that it is based on: RON Rule HLArc HLNode LHS NAC RHS HLTransition kind HLPlace type Token ObjectNet Codomain HLTransitionKind STANDARD APPLYRULE FIRE SPLIT HLPlaceType NET RULE ONArc weight ONNode Mapping ONPlace tokens capacity ONTransition The colors distinguish the milestones of the project: 1. In the first phase the object net (Petri net) editing capabilities were implemented 2. In the second phase rules were made editable 3. In the third phase the editing capabilities of high-level nets was added As already mentioned the project is implemented as an Eclipse plug-in. Additionally the Eclipse Modelling Framework (EMF) was used to create the underlying model (see above) and the Graphical Editing Framework (GEF) as basis for the editor. The underlying graph transformations are realized by the Attributed Graph Grammar System (AGG) a development environment for attributed graph transformation systems developed by the graph grammar group at TU Berlin. For further details, look at the project websites and refer to the JavaDoc based documentation for RON. 8

10 1.4. Installation The easiest way to install RON is to use the update feature of Eclipse: 1. Go to Help Software Updates Find and Install Select Search for new features to install and press Next 3. In Eclipse 3.2.x activate the Callisto Update Site, in Eclipse 3.3 activate the Europe Discovery Site. 4. Choose New Remote Site... and enter RON as name and as URL and confirm with OK. Make sure the newly-created RON item is also active. 5. Press Finish. 6. When asked for a mirror choose one an press OK. 7. Activate the RON item as a feature to install. 8. Press Select Required when an error about missing dependencies occurs. 9. Press Next, read and accept the license and press Next again. 10. Finally press Finish and confirm the restart of Eclipse. Important: You need at least Java 5 to use the editor. Note: RON was tested with Eclipse and Eclipse 3.3. Older and newer version are untested and may not work. You can also install RON from source, to do so extract the source archive to your workspace and import the project. Please refer to the Eclipse manual for further details. 9

11 Chapter 2 Example Workflow 2.1. Philosophers in library This is a step-by-step example guide. It will help you to create your first RON with the RONEditor and teach you the basic features and workflow of the editor. 1. First start Eclipse and create a new empty project. Go to File New Project... General Project 2. Enter Example as the Project Name. 3. Add a new RON to your project. Go to File New Other... Other RON File Creation Wizard 4. Choose the project Example under parent folder and stick to the suggested file name RON1.ron 5. Double click into the white area labeled RON1.ron. The RONView will show up. 10

12 6. Click on ObjectNetPlace in the Palette and then click into the white area with the label <default>. 7. You now can enter text into the little white box. Choose the text Library and hit return. 8. Repeat step 6 and 7 and name the new ObjectNetPlace Entrance-Hall. 11

13 9. Now choose RulePlace from the Palette, place it in the <default> area and name it leavelibraryrule. Repeat this step and name the other place enterlibraryrule 10. Choose Fire from the Palette, place it in the area and name it read. This will create a Fire-Transition. 12

14 11. Choose ApplyRule from the Palette, place it in the area and name it leavelib. Repeat it and create another ApplyRule and name it enterlib. 12. In the next step choose Arc from the Palette and fist click the fire transition and then click into the Library place. 13

15 13. Repeat the previous step and connect all places and transitions according to the picture below. 14. Choose Token from the Palette and click into the Entrance-Hall place. 14

16 15. Now select the Token labeled neu and change the name to philo1 You can change attributes like name of all elements via the Properties-View 16. Double click the philo1 token in the Entrance-Hall place. The ObjectNetView will show up. 15

17 17. Click on Place in the Palette, click into the philo1 area and name the place thinking. Change the attribute token to 1 via the Properties-View. 18. Click on Transition in Palette, click into the philo1 area and name the place think. 16

18 19. Choose Arc from the Palette and first click the think transition and then click into the thinking place. You can see that this is the same procedure like in the RONView. Create an additional Arc from thinking to think. 20. To close the ObjectNetView click the small " x" next to the philo1 label above the philo1 area (this is the way you close a view). Create another token in the same way you created the philo1 token and name the new token philo2 17

19 21. Create two additional token and place them into the RulePlaces and name them according to the picture below. 22. Now double click the enterlibrary token in the enterlibraryrule place. The RuleView will show up. 18

20 23. You can now edit the LHS of the rule via the lhs area. You can edit the lhs area like the area of an ObjectNetView. Create an net like in the picture below. 24. You can also edit the RHS of the rule via the rhs area. You can edit the rhs area like the area of the the LHS. Create an net like in the picture below. 19

21 25. Choose Map from Palette and click on thinking in the lhs and then click on thinking in the rhs. (This is the way you create mappings for rules) Close the RuleView like you did it with the ObjectNetView. 26. Repeat the rule creation procedure with the leavelib rule. Create the rule according to the picture below. When finished close the RuleView. 20

22 Congratulation you created your first simple RON with the help of the RONEditor. You can now try to fire the transitions by double clicking them. Note: If a transition can t fire it will be grayed out. After double clicking on the enterlib rule the View should look like the picture below. Try to fire other transitions and examine the modified philo tokens by double clicking on them. To learn more about the functionality of the other transitions look into the reference. 21

23 Chapter 3 Command reference 3.1. Basic features Copy & Paste There are several ways to copy and paste: 1. In the right-click popup menu by choosing Copy or Paste. 2. In the main menu with Edit Copy and Edit Paste, where the content of the clipboard will be pasted to the selected part. 3. In the toolbar by pressing for copy and for paste, where the content of the clipboard again will be pasted to the selected part Undo / Redo You can always undo and redo your work, in case you made a mistake: 1. In the right-click popup menu by choosing Undo or Redo. 2. In the main menu with Edit Undo and Edit Redo. 3. In the toolbar by pressing for undo and for redo Direct Edit Gives the possibility to edit components in the ObjectNetView directly. Select the component, then click on the text. (Example component transition): Now you can manipulate the text directly. ENTER or deselecting the component concludes your changes. 22

24 3.1.4 Properties View Proper- Figure 3.1: ties View Name and type of the components can be admitted or modified by selecting the object and writing into the object property view in the eclipse environment ObjectNet editor Figure 3.2: ObjectNet Editor 23

25 3.2.1 Palette The palette provides tools for creating an editing object nets. Figure 3.3: Palette ObjectNetView In the ObjectNetView you can see and edit object nets. Properties View The Properties View window is the one where you can view and modify the properties of the selected components. Components: Place, Transition Allows the creation of places and transition. Choose the component from the Palette and left-click somewhere into the ObjectNetView to place it there. You will be prompted for a name using the direct edit feature. Press the enter-key oder deselect the component the finish you entry. Component: Arc Allows the creation and positioning of Arcs in object nets. It is not possible to connect 2 places (or Transitions). You first choose in the palette the Arc component and then click one after another the target and source element in the ObjectNetView. Afterwards it is possible to set the edge weight. By hitting the enter key or by deselecting you conclude the entry. Component: MagicArc Enables to create and constitute automaticaly arcs with nodes in object nets. If there is already a Place drawed, it is possible to draw an Arc and the following according node by selecting MagicArcs and pressing the mouse button at the same time. If the previous node is a transition, repeated clicking the mouse button will generate a place otherwise, a transition will be generated. 24

26 3.3. Additional features Beside the basic functions for the creation of components the ObjectNet Editor provides additional functions for facilitating the creating of the layout and the editing GraphLayout Arranges places and transitions automatically. Click on the white background of the ObjectNetViews or click on it in the tree, to select the ObjectNet. With a click on the graph layout button in the toolbar, the layout of the object net is now computed and applied. You can, as always, undo you work if you are not satisfied with the automatic layout Fire Transition Allows to fire steps in a object net. If a transition is activated (can fire) it will be colored green, you can then select it and fire it by clicking (Fire Transition) in the toolbar or double-clicking it Rule Editor In fact the Rule Editor is a ObjectNet Editor with 3 seperate view. One view for the lhs,rhs and nac s. In addition to the ObjectNet Editor you are able to create mappings Palette The palette provides tools for creating and editing rules. In addition to the componets known from the ObjectNet Editor there is a new component for creating rule mappings. Figure 3.4: Palette Component: Map Creates mappings between nodes. You can create injective mappings by first clicking a place or a transition in the lhs. As a feedback it s border is colored red. Now select the place or transition in the rhs or nac. Remember that you can only match places with places and transitions with transitions. If the transition ist not pre- and postcompatible an error message is shown in the error log view. After 25

27 the match is created it will get a distinctive color. When you repeat the action on an active mapping it well get cleared Creating and deleting a nac You can create or delete a nac by selecting Create NAC or Delete NAC from the right-click popup menu. The nac-views also can be switched by the popup menu Copy Graphs You can copy lhs rhs or lhs nac by selecting the according command from the right-click popup menu High-Level Net editor Allows the editing of algebraic high-level nets with Petri nets, graphs and rules as tokens Palette The Palette allows you to generate or select components. Components can be transitions or places and arcs. Figure 3.5: Palette Transitions As we are dealing with RONs there is a fixed set of transitions you can choose from, you can select them from the Palette and later-on change the type via the Propeties View. The transitions will be colored red, if the transition is invalid so if the pre- and postconditions do not hold (refer to the defintion of RONs when in doubt). The color of the transition will be gray if it is inactive, so if it cannot fire. Finally the transition will get a color depending on the type if it is valid and it can fire. As with the object net, you can fire the transition by double-clicking it. 26

28 Component: STANDARD The STANDARD transition moves object nets and rules through the high-level network. You can model the operations delete, copy, move, union with it. Component: FIRE The FIRE transition allows you to fire the object nets, that lie on the input place. If there is more than one possibilty to fire the object net, you will be asked for the transition that should be fired. If more than one transition is applicable Fire Dialog is from the rightclick menu selectable. Component: APPLYRULE The APPLYRULE transition applies a net transformation rule on an object net. APPLYRULE is not applicable, a error dialog is shown. If If more than one match are possible Match Dialog is from the rightclick menu selectable. Component: SPLIT 27

29 The SPLIT transition allows you to split the object nets on the incoming places to be splitted in it s connected components. The connected components will be placed on the outgoing places. High-level places There are two types of high-level places. One that can hold object nets and one that can hold rules. Component: RulePlace The high-level place of type rule is a place which can contain rules. To edit a rule, double-click on the name and an editor window opens automatically. A high-level place of type rule can contain arbitrary rules. By mouse rollover a tooltip of the token is shown. It is possible to move rules that are on the places around via drag and drop. This way you can also change the order of the rules. Please note that you can only move object nets to places of the matching type. Component: ObjectNetPlace The high-level place of type object net is a place which can contain object nets. To edit an object net, double-click on the name and an editor window opens automatically. When a transition is fired the uppermost of the objects is taken. A high-level place of type object net can contain arbitrary object nets. It is possible to move object nets that are on the places around via drag and drop. This way you can also change the order of the object nets. Please note that you can only move object nets to places of the matching type. Component: Token Allows you to creates tokens. Selecting and clicking into a high-level place of type object nets will create an empty object net token. Selecting and clicking into a high-level place of type rule will create an empty rule token. Component: Arc 28

30 Allows the creation of Arcs. You can only create arcs between places and transitions (and vice versa) but not between two places or two transitions. To do so, first click on the start node and then click onto the end node. 29