On The Road to Hades–Helpful Automatic Development Email Summarization Alberto Bacchelli, Michele Lanza, Ebrisa Savina Mastrodicasa REVEAL @ Faculty of Informatics - University of Lugano, Switzerland Abstract—During the development of software systems, pro- Considered the numerous reasons why a programmer might grammers often discuss issues such as structural decisions, start an email conversation with a single colleague or the defects, time management, etc. Especially in distributed devel- entire rest of the team, and that a software project might opment, where most of the discussions among developers take place via email, developers receive daily dozens, if not hundreds, be carried out for several months or years, it is easy to of messages, either personally sent to them or broadcasted by picture the vast amount of produced emails. For example, on mailing lists they are subscribed to. Dealing with these emails the Apache developer mailing list, there were about 4,996 requires developers to spend long time reading voluminous messages in the year 2004 and 2,340 in 2005, and for gcc, amounts of text. these numbers were 19,173 and 15,082 [3]. To maintain A way to solve this problem is summarization: Producing a summary of a text means reducing it to a version based only team coordination and perform work on a software system, on fundamental elements, by removing the parts unnecessary software developers must keep track, read, and understand a for the comprehension. Since researchers presented techniques voluminous amount of electronic communication. This is a for automatically summarizing natural language documents challenge, not only because of the large number of emails– or source code, we are interested in investigating whether it which require time and effort to be read–popping up day after would be possible to also summarize development emails, so that developers could consult small summaries instead of long day in a developer’s mailbox, but also because retrieving threads. In this paper, on the basis of our first experiences past information from such messages can be time consuming in tackling development email summarization, we discuss the and frustrating. Sometimes, the amount of information may challenges that go hand in hand with such an endeavor. be overwhelming, causing messages to be left unread and searches to be abandoned, which in turn lead to duplicate, I. Motivation uncoordinated, or non-optimized work to be performed [15]. Software development projects, especially if large-scale, One way to alleviate this information overload issue is require a remarkable coordination effort amongst the project to provide a summary of development emails. A correct workers. Given the intensity and problems that come with and helpful summary (i.e., the text reduced to a version coordination, it is no wonder that coordination is considered without the parts unnecessary for the comprehension) enables the main reason why adding more developers to an ongoing developers to reduce the time spent reading new emails or software project might not speed up development [4]. perusing messages that have been returned from searches, Coordination is driven by communication. In co-located found through browsing, or recommended by team members. development teams, unplanned informal face-to-face meetings Given the growing amount of produced and recorded are the favorite form of communication when developers need textual information, often referenced as big data, there is to coordinate or face program comprehension problems [12]. substantial interest and a large body of work in the automated Personal meetings, besides disrupting developers’ attention generation of summaries for natural language documents, and and retaining knowledge by a few developers [10], are inap- software development related artifacts (e.g., [7], [15]). On plicable to distributed development projects. Developers, thus, the basis of the success of existing efforts on automatic replace face-to-face meetings with electronic communication summarization, we wonder whether it would be possible to means. Instant messaging, wikis, forums are viable options, devise a tool, which we call Hades, to automatically generate but the decisive role is played by emails, indeed: “Mailing helpful summaries of development emails. In this paper, we lists are the bread and butter of project communications” [6]. specifically analyze and discuss the challenges that go hand Emails are asynchronous, thus evade time zone barriers and in hand with such an endeavor. We investigate the challenges do not disrupt developers’s attention; mailing lists broadcast in devising a successful research methodology and in creating discussions, announcements, and decisions to all participants, an effective summarization technique to be implemented in thus maintaining developers’ awareness; emails are not bound a tool that can be used in real world scenarios. to specific abstraction levels (as opposed to commit messages, Structure of the paper: In Section II, we present existing design documents, or code comments), thus they can be and related work in the area of textual summarization; in used to discuss issues ranging from low-level decisions (e.g., Section III, we present the challenges that have to be tackled, implementation, bug fixing) up to high-level considerations both in terms of research method and in creating an effective (e.g., design rationales); mailing lists archive messages, thus approach; in Section IV, we discuss our findings from a offering a historical perspective. more high level perspective and conclude. II. Related Work III. Challenges After analyzing the related work in document and software Automatic summarization of documents written in natural artifact summarization, we started to investigate whether it language has been attempted by researchers for more than half could be possible to automatically generate helpful summaries a century [8]. We focus on efforts regarding summarization of development emails. By exploring possible research of emails and software development artifacts. methods and approaches to devise an effective technique, we found many unanswered questions while performing this Emails constitute a composite, chronologically ordered, task. In the following we analyze these open questions, so and structured (due to message metadata such as author, that we can see the state-of-the-practice in this topic and subject, or date) material that can be summarized with underline aspects that call for further studies. different methods. Lam et al. [11] proposed a system to summarize email messages by exploiting thread reply chains A. Methodology and commonly found features (like the proper names in Given the same development email, distinct people are very subjects found in the main sentences of the body). They likely to summarize it differently and give differing feedback asked four participants to use their system on their own on others’ summaries. This is true not only in the case of messages and provide feedback on the results. The gathered abstractive summaries (i.e., composing a document with new opinions were that the summary quality was either excellent sentences that express only the core messages), but also for or very bad (without intermediate results), the system worked extractive ones (i.e., selecting a subset of existing sentences best on either very short or very long email thread (sometimes, to form the summary). This situation binds the results of for short messages, reading the summary took longer), and any summarization approach to the subjective evaluation the system would have been useful to decide which email to of humans. To alleviate this issue, we have to follow a read first but it did not obviate the need to read it. Rambow et sound research method that considers the twofold nature (i.e., al. [14] proposed a technique to extract sentences exploiting quantitative and qualitative) of this topic. Unfortunately, there machine learning techniques. By considering a thread as a is no well-established research method: Researchers adopted single text, they fixed an incremental set of features that dissimilar approaches in their studies for both creating composed a vector view of every sentence in the thread itself. golden sets of summaries and evaluating the output of their They computed features that are usable for all text genres (e.g., approaches. Especially in the software engineering domain, the length of the sentence), features obtained considering where only few studies cover artifact summarization, the the thread broken into messages (e.g., absolute position of a proposed research methods appear scattered and inconsistent message in the thread), and features specific to the thread with one another. For this reason, the first open challenge structure (e.g., number of responses to a message, number of in this topic is finding a common base for a sound research recipients of a message). They presented results in terms of method. precision and recall with respect to a golden set of sentences We claim that the two main points when reasoning about selected by two human readers, but did not evaluate resulting the research method to use are the development email corpus summaries using word/string based similarity metric and/or and the participants to be involved in the study. human judgments. Other summarization efforts include the Corpus: Methodological questions regarding the corpus start one of Carenini et al., who built a fragment quotation graph to by deciding the population from