Back links and link discovery

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Back links and link discovery are different implementations of link relationships between artifacts in integrated tools. In both cases, integrations are based on the Open Services for Lifecycle Collaboration (OSLC) protocol. With back links, two artifacts are related to one another by a pair of links. Each artifact stores a link that points to the other artifact. With link discovery, artifacts are related by a single link.

Back links

When artifacts in different tools are related with back links, both artifacts detect that they are linked to each other because each artifact has a link to the other stored in its data. The relationship is expressed through the use of two separate links, as shown in the following figure.

The image shows two links between object 1 and object 2.

In this type of linking relationship, you do not need to complete extra operations, such as running a query, to discover traceability. However, you must ensure the symmetry and integrity of the linked data. For example, if you remove a link from Tool A, you must ensure that the corresponding link is removed from Tool B.

Link discovery

When link discovery is used to link artifacts, each relationship is expressed through the use of one link from a source artifact to a target artifact. The tool that contains the source artifacts is queried by the tool that contains the target artifact to determine which artifacts are linked.

The query is a supplemental operation. For example, even if Tool A has a set of links that point to Tool B, to complete a full traceability analysis, Tool A must run a query to know what is linked from Tool B.

The image shows a link from Tool A to Tool B and a discovered link from Tool B to Tool A.

In this type of linking relationship, one tool does not need to update the other tool when links are added or removed. However, to determine traceability, you must complete extra operations. To complete those operations, you typically must authenticate with the other tool's user database and you might need a license.

Linking with IBM applications

When you link to IBM® applications, back links are used with the applications in the Configuration Management (CM) domain. Link discovery is used with other applications in the Requirements Management (RM), Architecture Management (AM), and Quality Management (QM) domains.
Note: The integration with IBM Engineering Test Management (ETM) uses link discovery only if IBM Engineering Requirements Management DOORS® (DOORS) version 9.6.1.4 or later is integrated with Engineering Test Management version 6.0.1 or later, and the minimum client version of 9.6.1.4 is set on the DOORS database. If both conditions are not met, then back links are used.
When DOORS is integrated with another installation of DOORS, they are linked by using back links.
The following list shows how the links operate between DOORS and other applications:
  • Links from DOORS to IBM Engineering Requirements Management DOORS Next

    The source artifact stores the link.

    The target tool must perform a query against the source tool to discover which source artifacts have a link relationship with a specific target artifact.

  • Links from DOORS to ETM or IBM Engineering Systems Design Rhapsody® - Design Manager (RDM)

    The target artifact stores the link.

    The source tool must perform a query against the target tool to discover which target artifacts have a link relationship with a specific source artifact.

The following image shows these link relationships.

The image shows the linking implementation for the integration with QM, CM, RM, and AM tools.

*Links between DOORS and RDM or IBM Software Architect Extension for Design Management are always stored in the Design Management application, even if they were created in DOORS.