## 1 Introduction  
The World is generic and the user demands are rapidly changing as time goes by [1; 2]. The fundamental factor in the success of a software product line (SPL) is to understand what users really want [1; 2]. SPL is a paradigm where applications are derived from core assets which are built in domain engineering [3]. In order to fulfil user requirements, it is necessary for SPL organizations to know the opinions on the products that they have already floated on the market. The opinion may tell about user satisfaction which measures how software product, provided service, and overall user experience either falls short of or meets user expectations. Therefore, it is critical to monitor users' feedback in order to know what users really want. Otherwise, it will remain a dream to be ahead in a competitive software market and the privileges of organization's yesterday could be superseded by tomorrow's growing challenges. Social Network Services (SNS) are applications that connect users to each other by creating personal information profiles. Personal information may include photos, video, audio, location, likes, dislikes and area of interest [4]. In SNS, individuals are related (directly or indirectly) to each other based on common interest, friendship, or trust, etc. [5]. Using SNS, billions of users do their activities by building relationships, posting their opinions, or talking about their particular experiences. Recently, SNS have gained substantial attention from academia and industrial researchers. It has unlocked innovative ways of research in various fields like marketing, economics, arts, and information technology (IT) [6]. SNS users are growing exponentially [7] which provides highly diverse data that has brought revolution in many areas of data science. From the software engineering point of view, SNS have laid the foundation of unprecedented opportunities for software organizations to get instant feedback from a large number of their end-users [8]. Such feedback can be used to elicit new requirements and to plan the rapid evolution of software in the next release. SNS have been used in various phases of the software development lifecycle, such as project planning, Requirements Engineering (RE), and implementation of software projects [9]. In RE, SNS have demonstrated their ability in supporting and improving several process activities, such as requirements gathering [7; 9], negotiation [10], stakeholder identification and prioritization [11; 12] and many others. Several studies have used SNS to elicit user requirements from SNS. These [13; 14; 15] are representative examples where SNS are utilized to conduct RE activities. [PERSON] et al. [13] used Twitter to automatically identify, group, and rank tweets that are potentially relevant to software evolution. The tweets were classified into improvement request and others. [PERSON] et al. [14] have proposed an approach that extracts tweets from Twitter to elicit user requirements. The authors have classified tweets into bug reports, user requirements and others. They have extracted 949 user requirements and 1061 bug reports for 10 selected software products. [PERSON] et al. [15] have presented an empirical study which extracts user feedback from app stores. The authors have examined the usage of feedback features, the content of feedback, and its impact on the end-users. [PERSON] et al. [16] proposed an SNS-based process for minimizing the in-group bias as well as identifying stakeholders and eliciting user requirements. However, these research articles do not consider requirements engineering for SPL. The RE process for SPL should be in line with the aim of SPL. SPLs are designed aiming for short time-to-market, quality, and rapid development. Therefore, to successfully cope with short time-to-market time, the RE process used should be fast, easy and inexpensive. In this paper, we propose an SNS-based RE process to conduct RE activities. Our proposed approach collects user tweets and comments from Twitter and Facebook respectively.