Patent Publication Number: US-9430591-B2

Title: System and method for automatically determining relationships between software artifacts using multiple evidence sources

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is a continuation of U.S. patent application Ser. No. 13/855,400, filed on Apr. 2, 2013, which is a continuation of U.S. patent application Ser. No. 11/763,496, filed on Jun. 15, 2007, which claims the benefit of U.S. Provisional Patent Application Ser. No. 60/853,292 filed on Oct. 20, 2006, and entitled “System and Method for Automatically Determining Relationships between Software Artifacts Using Multiple Evidence Sources.” The disclosures of the aforementioned U.S. patent application Ser. Nos. 13/855,400 and 11/763,496, and U.S. Provisional Patent Application Ser. No. 60/853,292 are expressly incorporated herein by reference in their entireties. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the electrical, electronic, and software arts, and, more particularly, to techniques for software traceability. 
     BACKGROUND OF THE INVENTION 
     Software traceability is important in attaining effective end-to-end software engineering. Indeed, it is a significant factor in conducting and achieving a wide range of activities and goals, including tool integration, propagation of change, impact of change analysis, task assistance and semi-automation, consistency management, IT governance, and process assessment. Yet the software traceability problem has remained among the most intractable of problems for more than two decades. There are at least two issues that contribute to this intractability. First, people remain largely unmotivated to provide and evolve traceability information, as the stakeholder who knows the information is rarely the one who benefits from it. Second, even if the people were motivated, it is not feasible for humans to define and maintain traceability information throughout the course of evolution. There are too many stakeholders, too many software artifacts, too much evolution, and far too many interrelationships for this task to be addressed entirely by people. 
     Accordingly, automation has been attempted in the area of software traceability. Numerous researchers have attempted to automate the identification of artifact interrelationships, using a wide variety of techniques. These attempts have all experienced significant problems with scalability, reliability, correctness and usability and, as a result, none of them are currently in use in any real-world applications. Prior techniques have typically demonstrated different cost-benefit tradeoffs, particularly with respect to performance, precision, and recall. None of the techniques used have been considered efficient and reliable enough for use in real software processes. The limited sets of tools that developers have been offered to utilize traceability information have also demonstrated poor functional and usability characteristics. Fully automating the identification and evolution of interrelationships has not been possible, given that some relationship semantics are implicit and depend on human knowledge. 
     It would be desirable to overcome the limitations in previous approaches. 
     SUMMARY OF THE INVENTION 
     Principles of the present invention provide techniques for automatically determining relationships between software artifacts using multiple evidence sources. In one aspect, an exemplary method (which can be computer implemented) of inferring whether at least a first relationship exists between at least first and second entities includes the steps of applying a first assessor to obtain a first confidence level pertaining to putative existence of the at least first relationship between the at least first and second entities, applying a second assessor to obtain a second confidence level pertaining to putative existence of the at least first relationship between the at least first and second entities, and combining the first and second confidence levels to obtain an overall inference whether the at least first relationship exists between the at least first and second entities. The “entities” can include, by way of example and not limitation, one or more of software artifacts (further discussion is provided below), stakeholders, and tasks. 
     Information about one or more of assessors, relationships, and entities can be obtained by active and/or passive techniques. In one or more instances, steps are performed by a software tool (with human intervention as appropriate). Such tool can advantageously facilitate editing of the obtained information. A given pair of entities can be identified. These can be any two entities where we wish to check for the existence of one or more relationships between such entities. Two or more assessors are applied to obtain confidence levels in the existence of one or more relationships (for example, the at least first relationship mentioned above). In one simple case, we apply first and second assessors, but there is no limit to the number of assessors that can be applied, so that an additional step of can be performed of applying a plurality of additional assessors to obtain a plurality of additional confidence levels pertaining to putative existence of the at least first relationship between the at least first and second entities. In such a case, where additional assessors are employed, the step of combining the first and second confidence levels further includes combining the plurality of additional confidence levels to obtain the overall inference regarding the given candidate relationship. 
     Note that we can use more than two assessors, we can look for additional types of relationships between the same two entities, and we can look for the same or different relationships between additional entities. Thus, we can check whether there are one or more additional possible types of relationships between the two entities that were identified. If this is the case, appropriate steps can be repeated for such additional possible relationship(s). If such is not the case, a determination can be made whether we wish to examine one or more additional pairs of entities for the existence of one or more possible relationships. If such is the case, we identify another given pair of entities, and proceed as before. However, if we do not wish to examine additional entities, we can form a graph-like representation, as discussed below. 
     In one instance we could apply a third assessor to obtain a third confidence level pertaining to putative existence of at least a second relationship between the at least first and second entities, and could also apply a fourth assessor to obtain a fourth confidence level pertaining to putative existence of the at least second relationship between the at least first and second entities. We can combine the third and fourth confidence levels to obtain an overall inference whether the at least second relationship exists between the at least first and second entities. The third and fourth assessors are typically different than the first and second assessors, because we are looking for a different kind of relationship, but the invention is not limited to such case, as it is possible to have two assessors that are essentially the same but infer different relationships. 
     Further, in one instance, we could apply the first assessor to obtain a third confidence level pertaining to putative existence of the at least first relationship between at least third and fourth entities, and could also apply the second assessor to obtain a fourth confidence level pertaining to putative existence of the at least first relationship between the at least third and fourth entities. We could then combine the third and fourth confidence levels to obtain an overall inference whether the at least first relationship exists between the at least third and fourth entities. Of course, additional pairs can be examined for the same or different relationships than other pairs, depending on the types of relationships possible between the particular pair. 
     Thus, the described steps can be repeated for a plurality of additional entities and relationships. As noted, an additional step can include forming a graph-like representation depicting the relationships among the entities. We use the term “graph-like” rather than web-like to avoid confusion with the world-wide-web. The term “network” is also appropriate to refer to the representation. Another additional step can include updating the graph-like representation to reflect changes in the relationships. In one or more instances, at least some of the changes in the relationships result from changes in at least some of the entities. 
     As noted, in one or more embodiments, all of the steps are performed by a software tool (understood to include the possibility of human input to the tool as appropriate). In one or more instances, such a tool could include, by way of example and not limitation, one or more of (i) a list of candidate types of relationships including at least the first relationship and the second relationship, and (ii) a list of assessors for each of the candidate types of relationships, the list including at least the first and second assessors for the first relationship and the third and fourth assessors for the second relationship. In this case, an additional step could include facilitating editing of both the list of candidate types of relationships and the list of assessors for each of the candidate types of relationships by a user of the tool. 
     In the case where the entities are software artifacts, one non-limiting example of the at least first relationship is a “tests” relationship, that is, one artifact tests another artifact (specific non-limiting examples will be given below). In such case, the first assessor could be, by way of example and not limitation, a create-time assessor, a name matching assessor, a control flow assessor, a user interaction assessor, or a preceding version assessor. The second assessor would be a different assessor than the first assessor, again, by way of example and not limitation, a different assessor selected from the list in the prior sentence. Another possible example of a relationship between software artifacts is an “implements” relationship, discussed further below. 
     In a preferred approach, the combining step includes performing a summation discussed hereinbelow. In an alternative approach to the combining step, each of the first assessor, the second assessor, and the plurality of additional assessors represents the confidence levels as one of n discrete logical values, and the combining step includes a logical combination of the n discrete logical values. In one specific example, this can be done according to a 5-valued logic, such as “definitely,” “probably,” “possibly,” “definitely not,” and “inconsistent.” In this alternative example, weights are not employed. 
     As noted, information about one or more of assessors, relationships, and entities can be obtained by active and/or passive techniques. In general terms, regardless of whether active or passive techniques are employed, one or more steps can be repeated in a pair-wise manner for a plurality of additional entities and relationships. For each of the pairs of entities, additional steps to be performed can include determining which of a plurality of candidate relationships can apply to a given one of the pairs of entities, and determining which of a plurality of candidate assessors can apply to a given one of the plurality of candidate relationships for the given one of the pairs of entities. 
     In another aspect, an exemplary method of building a database associated with a central authority, the database comprising at least a plurality of candidate relationships and a plurality of candidate assessors, includes the steps of (i) facilitating registration of the plurality of candidate assessors with the central authority and (ii) facilitating registration of the plurality of candidate relationships. The registration of the plurality of candidate assessors includes data regarding which of the plurality of candidate relationships a given one of the candidate assessors is capable of assessing. The registration of the plurality of candidate relationships includes data regarding which kinds of entities a given one of the candidate relationships can apply to. 
     In yet another aspect, an exemplary method of building a database associated with a relationship manager program, the database comprising at least a plurality of candidate relationships and a plurality of candidate assessors, includes the steps of facilitating registration of the plurality of candidate assessors with the manager program, based at least in part upon input from human experts having assessor-related knowledge, and facilitating registration of the plurality of candidate relationships with the manager program, based at least in part upon input from human relationship experts having relationship-related knowledge. The registration of the plurality of candidate assessors includes at least indications of which of the plurality of candidate assessors can assess which kinds of the candidate relationships. The registration of the plurality of candidate relationships including at least indications of which of the plurality of candidate relationships can apply to given pairs of the plurality of entities. 
     One or more embodiments of the invention or elements thereof can be implemented in the form of a computer product including a computer usable medium with computer usable program code for performing the method steps indicated. Furthermore, one or more embodiments of the invention or elements thereof can be implemented in the form of an apparatus including a memory and at least one processor that is coupled to the memory and operative to perform exemplary method steps. 
     These and other features, aspects, and advantages of the present invention will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a flow chart of exemplary method steps according to an aspect of the invention, 
         FIG. 2  illustrates exemplary traceability relationships, according to an aspect of the invention; 
         FIG. 3  illustrates an exemplary initial relationship hierarchy, according to another aspect of the invention; 
         FIG. 4  illustrates an exemplary examination for a “tests” relationship, according to one exemplary application of an embodiment of the invention; 
         FIG. 5  is a view similar to  FIG. 4 , for the case of an evolving relationship; 
         FIG. 6  illustrates exemplary relationships of interest; 
         FIG. 7  shows an exemplary high-level architecture that can implement one or more inventive embodiments; and 
         FIG. 8  depicts a computer system that may be useful in implementing one or more aspects and/or elements of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     One or more embodiments of the invention can help developers manage software complexity by offering semi-automated support for capturing and mining relationships among artifacts and/or developer tasks at different stages of the software lifecycle. Developers can then use and manage information contained in the relationships. The use of these relationships can, in one or more instances, facilitate one or more of traceability, propagation of change, change impact analysis, evolution, and comprehension. As used herein, “facilitating” an action includes performing the action, making the action easier, helping to carry the action out, or causing the action to be performed. Thus, by way of example and not limitation, instructions executing on one processor might facilitate an action carried out by instructions executing on a remote processor, by sending appropriate data or commands to cause or aid the action to be performed. 
     Referring to  FIG. 1 , flow chart  100  shows steps in an exemplary method, according to an aspect of the invention, of inferring whether at least a first relationship exists between at least first and second entities. The method is preferably substantially computer-implemented with human intervention as appropriate. The method includes, in general terms, the steps of applying a first assessor to obtain a first confidence level pertaining to putative existence of the at least first relationship between the at least first and second entities; applying a second assessor to obtain a second confidence level pertaining to putative existence of the at least first relationship between the at least first and second entities; and combining the first and second confidence levels to obtain an overall inference whether the at least first relationship exists between the at least first and second entities. The steps of applying the first and second assessors are shown in block  110  of flow chart  100 , and the combining step is depicted in block  112 . 
     The “entities” can include, by way of example and not limitation, one or more of software artifacts (further discussion is provided below), stakeholders, and tasks. 
     The flow chart  100  will now be described in detail. After beginning at start block  102 , step  104  includes determining information about one or more of assessors, relationships, and entities. As will be discussed herein, such information can be obtained by active and/or passive techniques. As will be discussed further below, in one or more instances, steps are performed by a software tool (with human intervention as appropriate). Such tool can advantageously facilitate editing of the information obtained in step  104 , as shown at step  106 . At step  108 , a given pair of entities can be identified. These can be any two entities where we wish to check for the existence of one or more relationships between such entities. As noted, at block  110 , we apply two or more assessors to obtain confidence levels in the existence of one or more relationships (for example, the at least first relationship mentioned above). In one simple case, we applied first and second assessors, but there is no limit to the number of assessors that can be applied, so that an additional step of can be performed of applying a plurality of additional assessors to obtain a plurality of additional confidence levels pertaining to putative existence of the at least first relationship between the at least first and second entities. In such a case, where additional assessors are employed, the step of combining the first and second confidence levels further includes combining the plurality of additional confidence levels to obtain the overall inference regarding the given candidate relationship, as shown in step  112 . 
     Note that, for purposes of linguistic brevity, mention is made of “we applied,” “we wish” and so on; use of “we” does not necessarily imply human agency but is intended to also cover steps performed automatically, such as by the aforementioned software tool. 
     Note that we can use more than two assessors, we can look for additional types of relationships between the same two entities, and we can look for the same or different relationships between additional entities. Thus, decision block  114  involves checking whether there are one or more additional possible types of relationships between the two entities that were identified in step  108 . If this is the case, as per the “YES” branch of block  114 , steps  110  and  112  can be repeated for such additional possible relationship(s). If such is not the case, as per the “NO” branch of block  114 , another decision block can be executed, as at block  116 . Here, a determination is made whether we wish to examine one or more additional pairs of entities for the existence of one or more possible relationships. If such is the case, as per the “YES” branch of block  114 , we proceed to block  108  and identify another given pair of entities, and proceed as before. However, if we do not wish to examine additional entities, as per the “NO” branch of block  116 , we move on to block  118 , as discussed further below. 
     Thus, in one instance of the “YES” branch of block  114 , we could apply a third assessor to obtain a third confidence level pertaining to putative existence of at least a second relationship between the at least first and second entities, and could also apply a fourth assessor to obtain a fourth confidence level pertaining to putative existence of the at least second relationship between the at least first and second entities. We can combine the third and fourth confidence levels to obtain an overall inference whether the at least second relationship exists between the at least first and second entities. The third and fourth assessors are typically different than the first and second assessors, because we are looking for a different kind of relationship, but the invention is not limited to such case, as it is possible to have two assessors that are essentially the same but infer different relationships. 
     Further, in one instance of the “YES” branch of block  116 , we could apply the first assessor to obtain a third confidence level pertaining to putative existence of the at least first relationship between at least third and fourth entities, and could also apply the second assessor to obtain a fourth confidence level pertaining to putative existence of the at least first relationship between the at least third and fourth entities. We could then combine the third and fourth confidence levels to obtain an overall inference whether the at least first relationship exists between the at least third and fourth entities. Of course, additional pairs can be examined for the same or different relationships than other pairs, depending on the types of relationships possible between the particular pair. 
     Thus, the described steps can be repeated for a plurality of additional entities and relationships. As per block  118 , an additional step can include forming a graph-like representation depicting the relationships among the entities. We use the term “graph-like” rather than web-like to avoid confusion with the world-wide-web. The term “network” is also appropriate to refer to the representation. As per block  120 , another additional step can include updating the graph-like representation to reflect changes in the relationships. In one or more instances, at least some of the changes in the relationships result from changes in at least some of the entities. 
     As noted, in one or more embodiments, all of the steps are performed by a software tool (understood to include the possibility of human input to the tool as appropriate). In one or more instances, such a tool could include, by way of example and not limitation, one or more of (i) a list of candidate types of relationships including at least the first relationship and the second relationship, and (ii) a list of assessors for each of the candidate types of relationships, the list including at least the first and second assessors for the first relationship and the third and fourth assessors for the second relationship. In this case, an additional step could include facilitating editing of both the list of candidate types of relationships and the list of assessors for each of the candidate types of relationships by a user of the tool. One example of this step is block  106  of flow chart  100 . 
     In the case where the entities are software artifacts, one non-limiting example of the at least first relationship is a “tests” relationship, that is, one artifact tests another artifact (specific non-limiting examples will be given below). In such case, the first assessor could be, by way of example and not limitation, a create-time assessor, a name matching assessor, a control flow assessor, a user interaction assessor, or a preceding version assessor. The second assessor would be a different assessor than the first assessor, again, by way of example and not limitation, a different assessor selected from the list in the prior sentence. Another possible example of a relationship between software artifacts is an “implements” relationship, discussed further below. 
     In a preferred approach, the combining step  112  includes performing the summation: 
                     ∑     n   =   1     N     ⁢     (       V   n     ·     w   n       )             (   1   )               
where:
 
     each of the first assessor, the second assessor, and the plurality of additional assessors represents the confidence levels as a value, V n , between zero and one, with n indicating an nth one of the assessors, 
     w n  is a weight for the nth one of the assessors, and 
     N=the total number of assessors. 
     In one or more instances, the weights are all between 0 and 1 and sum to 1; in one or more instances, weights are assigned uniformly (that is, w n =1/N). 
     In an alternative approach to the combining step  112 , each of the first assessor, the second assessor, and the plurality of additional assessors represents the confidence levels as one of n discrete logical values, and the combining step includes a logical combination of the n discrete logical values. In one specific example, this can be done according to a 5-valued logic, such as “definitely,” “probably,” “possibly,” “definitely not,” and “inconsistent.” In this alternative example, weights are not employed. 
     As noted, step  104  includes determining information about one or more of assessors, relationships, and entities, and such information can be obtained by active and/or passive techniques. In general terms, regardless of whether active or passive techniques are employed, one or more steps in  FIG. 1  can be repeated in a pair-wise manner for a plurality of additional entities and relationships (as per the discussion of decision blocks  114  and  116 ). For each of the pairs of entities, additional steps to be performed can include determining which of a plurality of candidate relationships can apply to a given one of the pairs of entities, and determining which of a plurality of candidate assessors can apply to a given one of the plurality of candidate relationships for the given one of the pairs of entities. 
     Where an active technique is employed, the candidate relationships and the candidate assessors can be obtained by performing the steps of facilitating registration of the plurality of candidate assessors with a central authority and facilitating registration of the plurality of candidate relationships. The registration of the plurality of candidate assessors can include data regarding which of the plurality of candidate relationships a given one of the candidate assessors is capable of assessing. The registration of the plurality of candidate relationships can include data regarding which kinds of entities a given one of the candidate relationships can apply to. In some instances, the registration of the plurality of candidate assessors further includes data regarding which kinds of entities a given one of the candidate assessors is capable of assessing. 
     Stated in another way, in an exemplary active approach, one finds the two entities to be checked, looks up what type of entities they are, and sees what kinds of relationships can exist between those kinds of entities, and what kinds of assessors can assess those kinds of relationship(s). An assessor can “declare” the types of relationships it knows how to assess and different types of relationships can be registered, and the types of the entities that such relationships can apply to can also be registered. Assessors are typically registered by the type of relationships they know how to assess, and registration by the types of entities they know how to assess may also be useful. 
     The active approach can be conducted in conjunction with other method steps, or as an independent method, or as some combination thereof. Thus, an exemplary method of building a database associated with a central authority, the database comprising at least a plurality of candidate relationships and a plurality of candidate assessors, includes a step of facilitating registration of the plurality of candidate assessors with the central authority. The registration of the plurality of candidate assessors includes data regarding which of the plurality of candidate relationships a given one of the candidate assessors is capable of assessing. The method also includes the step of facilitating registration of the plurality of candidate relationships. The registration of the plurality of candidate relationships includes data regarding which kinds of entities a given one of the candidate relationships can apply to. Optionally, the registration of the plurality of candidate assessors further includes data regarding which kinds of entities a given one of the candidate assessors is capable of assessing. 
     An exemplary passive technique will now be discussed. In one or more instances, there are human experts that understand what the relationships are and which assessors to apply to assess them. The relationships and assessors can be registered. Assessors are built to assess whether a given relationship holds between two elements. Such relationships only make sense between elements of a certain type (for example, the relationship “FatherOf” only makes sense between two people; not between a person and an inanimate object). When an element is created or changed in the system, it is advantageous to be able to determine the relationships in which it participates. A manager program can be notified of such create and/or change events, and can apply any applicable assessors between the new element and other elements to create the necessary relationships. Since not all assessors assess relationships that make sense for that type of element, the manager program is advised which ones do (that is, which ones are applicable) through a registration process. The decision about which assessors should be registered as applicable to which types of elements can be made by a human being who programs it into the system. 
     Thus, in an exemplary passive technique, the candidate relationships and the candidate assessors are obtained by performing the steps of facilitating registration of the plurality of candidate assessors with a manager program and facilitating registration of the plurality of candidate relationships with the manager program. The facilitating registration of the plurality of candidate assessors with the manager program can be based, at least in part, upon input from human experts having assessor-related knowledge. The registration of the plurality of candidate assessors can include at least indications of which of the plurality of candidate assessors can assess which kinds of the candidate relationships. The facilitating registration of the plurality of candidate relationships with the manager program can be based, at least in part, upon input from human relationship experts having relationship-related knowledge. The registration of the plurality of candidate relationships can include at least indications of which of the plurality of candidate relationships can apply to given pairs of the plurality of entities. The determining which of the plurality of candidate relationships can apply to a given one of the pairs of entities and the determining which of the plurality of candidate assessors can apply to a given one of the plurality of candidate relationships for the given one of the pairs of entities can be done by executing the manager program (refer to exemplary discussion of element  718  in  FIG. 7  below). 
     The passive approach can be conducted in conjunction with other method steps, or as an independent method, or as some combination thereof. Thus, an exemplary method of building a database associated with a relationship manager program, the database comprising at least a plurality of candidate relationships and a plurality of candidate assessors, includes a step of facilitating registration of the plurality of candidate assessors with the manager program, based at least in part upon input from human experts having assessor-related knowledge. The registration of the plurality of candidate assessors includes at least indications of which of the plurality of candidate assessors can assess which kinds of the candidate relationships. The method also includes the step of facilitating registration of the plurality of candidate relationships with the manager program, based at least in part upon input from human relationship experts having relationship-related knowledge. The registration of the plurality of candidate relationships includes at least indications of which of the plurality of candidate relationships can apply to given pairs of the plurality of entities. 
     Based on the description thus far, it will be appreciated that one or more inventive embodiments advantageously find the “sweet spot” between (i) manual input from the user and (ii) automation, by leveraging information about the stakeholders&#39; tasks. The herein-described traceability relationship identification and evolution technique can be referred to as semi-automated relationship inferencing (SARI), and can cover both the initial identification of these relationships, as well as the removal of relationships when they become, for example, incorrect, useless, or irrelevant. Traceability relationships include, for example, the relationship between code and the design it implements, between a test case and the code it tests, and between a design and the use case(s) it realizes. One or more inventive embodiments can address a subset of common traceability relationships. SARI can, in one or more embodiments, exhibit one or more of the following characteristics:
         For each type of relationship, multiple techniques are combined, according to one or more inventive aspects disclosed herein, to identify new relationships and discard invalid ones. In this way, one or more embodiments leverage the best features of a variety of techniques to produce better results, while minimizing their individual weaknesses. Moreover, the architecture is open and extensible—new techniques can be incorporated at any time.   Relationships between existing artifacts are identified (not just when artifacts are created) so no unrealistic assumptions about starting from scratch need be made. Relationships can also be captured during the artifact creation process, a time when more information is often available to help with the creation of such relationships. For example, it is easy to tell which code is being tested at the point where a developer creates a test case for that code. It is comparatively more difficult to determine this information once the test case exists.   One or more embodiments of SARI assign qualitative “goodness” ratings to each relationship, as well as an explanation for why it is believed that the relationship is valid. This enables stakeholders to understand and control the tradeoff between completeness and accuracy.   One or more embodiments feature incrementality and scalability.       

     When one or more embodiments of the semi-automated inferencing engine identify problematic relationships (ones they cannot resolve by themselves), help can be solicited from the user, preferably in a non-intrusive, focused manner, thus minimizing the amount of effort an unwilling stakeholder has to put into maintaining traceability information. By combining a variety of novel and user-friendly techniques, one or more inventive embodiments help stakeholders to develop, evolve, and use traceability effectively to manage software complexity. Semi-automated support can be provided for capturing and mining relationships among artifacts and/or developer tasks at different stages of the software lifecycle, and this can help stakeholders to use these relationships to facilitate one or more of traceability, propagation of change and change impact analysis, evolution, task assistance and semi-automation, assessment, and comprehension. 
     Further discussion will now be provided regarding application of exemplary inventive techniques to the software lifecycle. As discussed above, relationships among entities may be inferred. Exemplary types of entities include stakeholders, software artifacts, and tasks. This list is not intended to be limiting. Software artifacts can include, by way of example and not limitation, products of a piece of work, such as a word processing document, a presentation, a spreadsheet, and so on. In general, an artifact is a result of some process. Processes can include software development, governmental processes, mathematical processes, scientific processes, and so on; indeed, anything that can be represented in some accessible medium. We seek to determine whether relationships exist between artifacts; for example, between two stakeholders, between a stakeholder and an artifact, between a task and a stakeholder who performs it, between a task and an artifact, between two tasks, and so on. Traceability relationships in the software lifecycle thus relate corresponding artifacts across phases of the lifecycle and across artifact versions. With reference to  FIG. 2 , a plurality of use cases  202  may lead to a plurality of model designs  204 , for example in the UML unified modeling language. These model designs may in turn lead to JAVA code  206  and associated JUnit test cases  208 . (JAVA is a general-purpose, class-based, object-oriented language.) JUnit is a well-known simple framework for writing repeatable tests and is an instance of the XUnit architecture. 
     By way of a simple example, we might have two word processing documents. We seek to determine if they are related, and, if so, what kind of relationship(s) exist. For example, if the two entities were people, they might have the relationship father of child, husband of wife, employee of employer, and so on. The different techniques for determining whether a particular relationship exists have been referred to herein as assessors. In the case of the two word processing documents, exemplary assessors could include natural language analysis of the contents, or the structure of the documents, and so on. Thus, in one or more instances, implicit relationships between entities are found, made explicit, and connected up into a graph-like structure. 
     Additional non-limiting examples of entities, relationships, and assessors will now be provided. With reference to  FIG. 3 , an initial relationship hierarchy  300  begins with the most general case of “related to,” at location  302 . A next level includes the possible relationships “feature of,” “realizes,” “refines,” “depends on,” “tests,” “stakeholder of,” and “relates stakeholders,” labeled  304  through  316  respectively. Location  306  branches out to “pertains to”  318  and “implements/realizes”  320 . “Depends on”  310  branches to “refers to”  322  which in turn branches to “contains/comprises”  324 , “demonstrates problem in”  326 , and “uses”  328 . The latter in turn branches to “invokes”  330  and “data used by/member used by”  332 . “Invokes”  330  branches to “in control flow of”  334  and “exercises/invokes”  336 . “Test (code, test)”  338  is a branch of both  336  and  312 . “Test (req, test)”  340  is a branch of  312 . 
     Still referring to  FIG. 3 , relationship  316  branches to “successor of”  342  and “manages”  344 . Relationship  314  branches to “owner of,” “knows,” “originates,” “architects,” and “realizes,”  346 - 354  respectively. “Knows”  348  can include “expert on”  356 . 
     With reference now to  FIG. 4 , consider the “tests’ relationship  312 . This relationship can be between a piece of source code, such as “C1” code  402 , and the test case, such as “TestC1”  404 , that tests it to see if it is correct. Many different types of assessors could be used to see if such a relationship exists, for example, an “invokes” assessor sees whether the test case invokes the method in the source code and a “name-matching” assessor sees if the names indicate a relationship. There may be a standard naming convention, such that, for example, “test” is pre-pended to the name of the code segment to be tested to get the name of the test case for that segment. A “control flow” assessor checks whether anything that the test case calls, whether directly or indirectly, is in the source code; if so, a relationship exists. An “implements” assessor sees whether the real code implements the “sketch” of the code. A model or sketch is often made of code before actual code is written. Such model or sketch may be similar to a “storyboard” and can include, for example, pseudocode (or may be even less concrete than pseudocode). The models or sketches are often created in one tool and the actual code in another tool. The “implements” assessor finds such connections by, for example, inferring a connection between a sketch or model of a class, and the actual class. A “user interaction” assessor allows a human user to advise whether a relationship exists. Yet another possible assessor is a “preceding version” assessor which sees whether there was a relationship of the given kind between previous versions of the given elements. This particular assessor may be relatively weak. 
     In the example of  FIG. 4 , four assessors are employed, namely, JUnit create-time assessor  406 , labeled “A,” name matching assessor  408 , labeled “B,” control flow assessor  410 , labeled “C,” and user interaction assessor  412 , labeled “D.” The JUnit create-time assessor is an example of a highly reliable assessor; in the Eclipse software environment, when a JUnit test case is created, one can specify at such time exactly what JAVA code it is intended to test. Here, as indicated at  414 , assessors A, B and C are run to see if a “tests” relationship exists between C1 and TestC1; they indicate, respectively, “definitely,” “possibly,” and “definitely” and are combined to yield an overall score of “definitely.” Then, at  416 , we examine for a “tests” relationship between “foo” and testFoo.” Assessors B and C yield, respectively, “possibly” and “definitely,” resulting in an overall assessment of “possibly.” At  418 , we look for a “tests” relationship between “bar” and TestBar”. Assessors B, C and D yield, respectively, “possibly,” “definitely not,” and “definitely,” resulting in an overall assessment of “definitely.” Finally, at  420 , we look for a “tests” relationship between “bar” and “testFoo.” Assessor C yields a result of “definitely” leading to an overall conclusion of “definitely.” 
     As noted, one or more inventive embodiments lead to a map of relationships between entities. Updates over time can be detected. For example, if one married one&#39;s fiancé, the relationship would change from “fiancé” to “spouse.” Changes in relationships may be a result of changes in entities themselves, for example, editing the word processing document in the above examples. Attention should now be given to  FIG. 5 , which is similar to  FIG. 4 , except as described hereinafter. Elements in  FIG. 5  similar to those in  FIG. 4  have received the same reference character incremented by 100, and will not be described again except to the extent that they differ substantially form those in  FIG. 4 .  FIG. 5  shows one example of how inventive techniques can be applied to relationships that evolve over time. Here, “testFoo” has been renamed to “testFoo2.” Now the name matching assessor yields “definitely not” while the control flow assessor yields “definitely,” and the overall result is “inconsistent,” as at  516 . 
       FIG. 6  gives some additional specific, non-limiting examples of interesting relationships. The “depends on” relationship  602  includes more specific cases such as “uses”  604 , “tests”  606 , and “demonstrates problem in”  608 . Blocks  604  and  606  can each lead to “exercises” relationship  610 . “Implements”  614  is a special case of “realizes”  612 , and “expert on”  618  is a special case of “stakeholder of”  616 . 
     An advantage of one or more embodiments of the invention is that the skilled artisan can implement assessors using whatever techniques he or she likes. Advantageously, such embodiment(s) provide such artisans with support in building and running their assessors to do traceability inferencing, regardless of the techniques they choose to do the assessment. 
       FIG. 7  shows an exemplary system architecture  700  that can be used to implement one or more embodiments of the invention. A first tool  702  creates a design  704 , while a second tool  706  creates a code segment  708 . We desire to see if block  708  implements  704 ; as shown at block  710 , the overall assessment is “probably” and an appropriate explanation for the result can be displayed, for example, as shown with regard to  FIGS. 4  and  5 . A third tool  712  creates test case  714  and we seek to determine whether block  714  tests block  708 . As per block  716 , the overall assessment is “definitely,” and again, an appropriate explanation can be displayed. Relationship manager  718  monitors all the just-described elements, and includes, by way of example and not limitation, assessors  720  that can assess the “expert on” relationship, assessors  722  that can assess the “implements” relationship, and assessors  724  that can assess the “tests” relationship. Human expert  726  may have an “expert on” relationship with design  704 . 
     A variety of techniques, utilizing dedicated hardware, general purpose processors, firmware, software, or a combination of the foregoing may be employed to implement the present invention or components thereof. One or more embodiments of the invention, or elements thereof, can be implemented in the form of a computer product including a computer usable medium with computer usable program code for performing the method steps indicated. Furthermore, one or more embodiments of the invention, or elements thereof, can be implemented in the form of an apparatus including a memory and at least one processor that is coupled to the memory and operative to perform exemplary method steps. 
     One or more embodiments can make use of software running on a general purpose computer or workstation. With reference to  FIG. 8 , such an implementation might employ, for example, a processor  802 , a memory  804 , and an input/output interface formed, for example, by a display  806  and a keyboard  808 . The term “processor” as used herein is intended to include any processing device, such as, for example, one that includes a CPU (central processing unit) and/or other forms of processing circuitry. Further, the term “processor” may refer to more than one individual processor. The term “memory” is intended to include memory associated with a processor or CPU, such as, for example, RAM (random access memory), ROM (read only memory), a fixed memory device (for example, hard drive), a removable memory device (for example, diskette), a flash memory and the like. In addition, the phrase “input/output interface” as used herein, is intended to include, for example, one or more mechanisms for inputting data to the processing unit (for example, mouse), and one or more mechanisms for providing results associated with the processing unit (for example, printer). The processor  802 , memory  804 , and input/output interface such as display  806  and keyboard  808  can be interconnected, for example, via bus  810  as part of a data processing unit  812 . Suitable interconnections, for example via bus  810 , can also be provided to a network interface  814 , such as a network card, which can be provided to interface with a computer network, and to a media interface  816 , such as a diskette or CD-ROM drive, which can be provided to interface with media  818 . 
     Accordingly, computer software including instructions or code for performing the methodologies of the invention, as described herein, may be stored in one or more of the associated memory devices (for example, ROM, fixed or removable memory) and, when ready to be utilized, loaded in part or in whole (for example, into RAM) and executed by a CPU. Such software could include, but is not limited to, firmware, resident software, microcode, and the like. 
     Furthermore, the invention can take the form of a computer program product accessible from a computer-usable or computer-readable medium (for example, media  818 ) providing program code for use by or in connection with a computer or any instruction execution system. For the purposes of this description, a computer usable or computer readable medium can be any apparatus for use by or in connection with the instruction execution system, apparatus, or device. 
     The medium can be an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system (or apparatus or device) or a propagation medium. Examples of a computer-readable medium include a semiconductor or solid-state memory (for example memory  804 ), magnetic tape, a removable computer diskette (for example media  818 ), a random access memory (RAM), a read-only memory (ROM), a rigid magnetic disk and an optical disk. Current examples of optical disks include compact disk-read only memory (CD-ROM), compact disk-read/write (CD-R/W) and DVD. 
     A data processing system suitable for storing and/or executing program code will include at least one processor  802  coupled directly or indirectly to memory elements  804  through a system bus  810 . The memory elements can include local memory employed during actual execution of the program code, bulk storage, and cache memories which provide temporary storage of at least some program code in order to reduce the number of times code must be retrieved from bulk storage during execution. 
     Input/output or I/O devices (including but not limited to keyboards  808 , displays  806 , pointing devices, and the like) can be coupled to the system either directly (such as via bus  810 ) or through intervening I/O controllers (omitted for clarity). 
     Network adapters such as network interface  814  may also be coupled to the system to enable the data processing system to become coupled to other data processing systems or remote printers or storage devices through intervening private or public networks. Modems, cable modem and Ethernet cards are just a few of the currently available types of network adapters. 
     In any case, it should be understood that the components illustrated herein may be implemented in various forms of hardware, software, or combinations thereof, for example, application specific integrated circuit(s) (ASICS), functional circuitry, one or more appropriately programmed general purpose digital computers with associated memory, and the like. Given the teachings of the invention provided herein, one of ordinary skill in the related art will be able to contemplate other implementations of the components of the invention. 
     It will be appreciated and should be understood that the exemplary embodiments of the invention described above can be implemented in a number of different fashions. Given the teachings of the invention provided herein, one of ordinary skill in the related art will be able to contemplate other implementations of the invention. Indeed, although illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various other changes and modifications may be made by one skilled in the art without departing from the scope or spirit of the invention.