Connection is a special flow element that serves to interconnect other flow elements. The network of connections in a flow determines how jobs can travel between the flow elements.
To connect two flow elements that are already present on the canvas, do one of the following:
-
Drag the connection icon from the Elements pane and drop it onto the first flow element; then click on the second flow element or
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Double-click the first flow element to start a connection and drop it on the second flow element to connect it with the first flow element or
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Select "Start connection" in the context menu of the first flow element and drop the extension on the second flow element.
Keywords
Keywords can be used with the search function above the Flow Elements pane.
The keywords for the Connection element are:
- move
- filter
- traffic-light
Flow element types
In terms of connectivity, there are four types of flow elements (other than connection itself):
Flow element type |
Description |
|---|---|
Folder |
Represents a folder on disk that can hold jobs before, after or in between processing steps; folder has a central role in Switch (see below) |
Processor |
Processes jobs and thus accepts incoming and outgoing connections |
Producer |
Injects jobs into a flow from an outside source (such as an email inbox); a producer does not accept incoming connections |
Consumer |
Consumes jobs from a flow and possibly transports them to an outside target (such as an FTP site); a consumer does not allow outgoing connections |
The central role of folder
At least one of the two flow elements being connected must be a folder. In other words, a flow element other than a folder can be connected only to a folder.
A simple rule of thumb is "there must always be a folder in between".
Connection types
There are several types of connections, each with a slightly different set of properties. The type of a connection is determined by the flow element from which the connection originates. All connections originating at a particular flow element have the same type. Some flow elements also restrict the number of outgoing connections.
Connection type |
Description |
|---|---|
| Move | Simply moves jobs along (under the control of Switch); a flow element with outgoing move connections often produces only a single output along one of the outgoing connections (for example, file balancer), or it may allow just one outgoing connection |
Filter |
Offers properties for file filtering in addition to the move properties; a flow element with multiple outgoing filter connections (for example, folder) usually sends identical copies of its output along these connections (assuming a connection's filter allow the output to pass) |
| Traffic-light | Offers data and log subtypes and allows to set success-, warning- and error- filters; this connection type is used by flow elements that produce a report for human consumption and/or validate jobs against some specified rules (for example, preflight); multiple connections of the same subtype carry identical copies of the output |
| No-options | Jobs are moved under the control of a third-party application; this connection type is used only in conjunction with generic application; it offers only the most basic set of properties |
Properties
The following table lists the properties for all connection types (i.e. no single connection offers all of these properties). Some flow elements "inject" extra properties in their outgoing connections. These properties are described with the flow element that injects them.
Property |
Description |
|---|---|
Name |
The name of the connection displayed in the canvas; most connections have a blank name (the default) but the user can add a name if so desired; some flow elements use the name of their connections for special purposes (these rare cases are described for each flow element where applicable) |
Corner angle |
Determines the layout of a connection as it is drawn on the canvas Consider the rectangle formed by drawing horizontal and vertical line segments through the center of the two flow elements being connected; the breakpoint in the connection line can be positioned anywhere on the diagonal of this rectangle The corner angle is an integer number in the range [-90, 90] inclusive; the value is a measure for how much the corner formed at the breakpoint differs from a straight line; thus a zero value means a straight line (the default) and a value of ±90 means a rectangular corner (the breakpoint is positioned at one of its extremes) |
Hold jobs |
While set to yes, jobs are not allowed to move through the connection; this is mostly used to temporarily hold jobs (perhaps because there is a problem with a process downstream) The value of this property can be modified while the flow is active (through a canvas context menu item); see putting connections on hold |
Include these jobs |
Jobs that match the specified filter are moved through this connection, unless they are explicitly excluded (see next property); refer to Specifying file filters for more details |
Exclude these jobs |
Jobs that match the specified filter are never moved through this connection; refer to Specifying file filters for more details |
Include these folders |
Subfolders that match the specified filter are included for this connection; injected by producers that retrieve jobs from an outside folder hierarchy, such as FTP receive; refer to Specifying file filters for more details |
Exclude these folders |
Subfolders that match the specified filter are ignored for this connection; injected by producers that retrieve jobs from an outside folder hierarchy, such as FTP receive; refer to Specifying file filters for more details |
Carry this type of jobs |
Determines the type of files carried by this connection:
|
Dataset name |
If the previous property is set to "Data with log", this property defines the name of the metadata dataset containing the log file attached to the data file; see Picking up metadata |
Success out |
If set to yes, a file will move along the connection if the originating process did not log any warnings or errors |
Warning out |
If set to yes, a file will move along the connection if the originating process logged at least one warning and no errors |
| Error out | If set to yes, a file will move along the connection if the originating process logged at least one error |