JOpera for Eclipse

11.1: Versioning

11.1.1: Introduction

The versioning represents an extension to JOpera aiming at a better version management of processes and programs. It enables to qualify a version with a tag, e.g. stable, unstable or deprecated, and provides UI functionalities to duplicate existing entities and increment automatically their version number.

11.1.2: Use

The use of versioning is straightforward. The general information section, as seen in Figure 11.1, provides a line for version management and a few corresponding widgets.

Figure 11.1: The versioning widgets in the general information section

Duplication

A duplication of the current process or program is performed when the Create New Version button is clicked. By doing so, the version number is automatically incremented.

Deletion

Similarly, the deletion of the current process or program is executed when the Delete this Version button is pressed.

Tagging

The tagging of the entity currently displayed is done by mean of the combo menu, as shown in Figure 11.2.

Figure 11.2: Tagging an entity

Outline

The outline, in JOpera design mode, has been slightly extended to group all same entities with different version numbers together under their common entity name, as seen in Figure 11.3.

Figure 11.3: Outline view

11.2: database setup

For the Lineage module to work, in particular the memoization, lineage browser and logger, it is necessary to set up a PostgreSQL database. The database should be accessible from the host where JOpera runs, in case it is not local. This means that the right host authorization line should be present in the pg_hba.conf PostgreSQL configuration file, like for instance the following one:

host    all         all         192.168.1.0/24       md5

Which allows a database access with md5 authentication for a JOpera client that is on the subnet 192.168.1.0/24. Additionally, a user and password should be set up. The next step is to enter the database connection information in JOpera. This can be done using Eclipse Jopera's preference page as seen in Figure 11.4.

Figure 11.4: Database settings

11.3: Memoization

11.3.1: Introduction

Memoization allows executed instances of programs or processes to get cached in the database. Later on, a reexecution of the same entity with the same input parameters can be restored directly from database without being reexecuted. This is especially interesting for entities that are either fully deterministic or deterministic within a certain time window, and in addition, have a large execution latency.

11.3.2: Use of Memoization

Execution Logging

The use of memoization for JOpera is straightforward and can be done using JOpera UI. The tooling is integrated in the execution section, just underneath the general information section, which are both visible in design mode. A screenshot of the execution settings section is presented in Figure 11.5.

Figure 11.5: Memoization parameters

The memoization settings are on the first line of the panel, which is only present if the jopera.ui.lineage plug-in has been installed. We see in Figure 11.5 the case were memoization has been switched off for the current process by ticking the Disabled radio box. It is interesting to note that each process or program has got its own memoization settings, so a fine granularity of which entities have their execution logged to the database for memoization is possible. Figure 11.6 shows the case, where memoization is turned on. This is done by ticking the Deterministic radio button on the panel.

Figure 11.6: Memoization turned on

In case a process or program is not fully deterministic but has an execution that can be seen as deterministic inside a certain time window, it is also possible to use the memoization module. Such a process could be some web service returning information that has a certain time of validity, like a stock quotation or an exchange rate service. As a web service, or another service type having a non-negligible latency, it can be interesting to cache its result during the validity period to increase the system performance. The Figure 11.7 shows a setting where the data of some execution will remain valid during a one-hour time span, specifying a cache duration in seconds of 3600.

Figure 11.7: Caching with a one hour lifetime

Used of Cached Data

The last step is to use the cached data from the database during process execution. This is a setting that appears in the launcher panel. In the second tab, Start Options, the radio button Use Cached Execution Data if Available needs to be ticked. This can be seen in the Figure 11.8.

Figure 11.8: Memoization launch configuration

11.4: Lineage Tracking

11.4.1: Introduction

The goal of lineage tracking is, on the one hand, to perform logging of lineage data during process execution, and on the other hand, to allow a confortable browsing of this data, accumulated in the database. The former is performed automatically during process execution and the latter is done using four main components.

• The lineage summary: this view shows the entities logged in the database. It shows various of their attributes and enables to choose one of them and go to the instance browser.
• The instance browser: this view shows a list of instances from an entity along with a certain number of relevant parameters. it is possible to choose an instance and view it in the next component, the lineage browser.
• The lineage browser: this is a graphical component that enables to view graphically programs and processes as well as their relation with respect to lineage tracking. It is possible to browse their hierarchy and dependence. When an entity is selected, its complete property set shows up in the property view.
• The property view: visualize the properties of an entity selected in the lineage browser.

11.4.2: Lineage Summary

As mentioned above, this panel is used to visualize the entities, processes and programs, that have been logged to the database. A certain number of attributes like, among others, name, package, version or description can be seen. A screenshot of the lineage summary can be observed in Figure 11.9.

Figure 11.9: The lineage summary

When an entity is double-clicked, the second view, the instance browser, shows up, listing its instances. When the refresh icon on the right of the task bar is pressed, as seen in Figure 11.10 the list gets fetched again from the database. The refresh function is also accessible from the context menu.

Figure 11.10: The refresh icon

11.4.3: Instance Browser

The instance browser lists the instances of a certain entity logged in the database. In this view, attributes like the input and output parameters along with the execution time and various execution timestamps can be examined. Figure 11.11 shows the instance browser.

Figure 11.11: The instance browser

A search among the available instances can be performed using the search panel. It can be chosen, as seen in Figure 11.12, if we want to find tuples with an attribute containing, starting, ending or exactly equal to the value entered in the text field. All instances that have any attribute matching the search pattern is then retrieved.

Figure 11.12: The search capability

After having entered a search string and pressed the search button or pressed return, the result shows up, like in Figure 11.13.

Figure 11.13: The search result

Here as well, like in the summary view, the refresh button on the top right of the view can be used to refresh the view content. Additionally, when an instance in the instance browser is double-clicked, the corresponding graphical element shows up in the lineage browser panel.

11.4.4: Lineage Browser

The lineage browser is used to browse graphically the entities instances. A starting point could be what is seen in Figure 11.14.

Figure 11.14: A process in the lineage browser

When a process is double-clicked, it is opened or closed, depending of its initial state. We see for instance in Figure 11.15 the initial process that has been opened, displaying its internal task.

Figure 11.15: A process that has been opened

Any entity that is selected, displays its properties in the property panel, as seen in Figure 11.16.

Figure 11.16: Properties of a selected entity

The contextual menu over an entity displays what can be done with it. Commands from the following list are available.

• Get Parent: retrieves hierarchical data from the database and shows the selected entity in its parent context.
• Set New Root: a child entity can be chosen as the new root of the graphical representation
• Expand All: recursive open of the complete subtree rooted by the selected element
• Collapse All: recursive close of the complete subtree
• Expand Process: open the selected process, equivalent to a double-click on it.
• Collapse Process: close the selected process, equivalent to a double-click on it.

We see a screenshot of the context menu in Figure 11.17.

Figure 11.17: Context menu of the lineage browser

Finally, we see the result of the previous process after having run the Get Parent command in Figure 11.18. ProcB is here represented, as mentioned, in its parent context of ProcA.

Figure 11.18: The result of Get Parent

11.4.5: Property Panel

The property panel is just a normal property panel, as shown in Figure 11.16. It simply displays the properties of the selected item of the lineage browser.