Inclusion and exclusion criteria.

Table 4: Inclusion and exclusion criteria.

Criteria		Rationale
Inclusion	I1: Studies in the form of academic peer-reviewed conference and journal articles.	Peer-reviewed papers guarantee a level of quality and the well-trusted volume of content.
	I2: Studies published between 2006 and January 2018.	Eleven years has been selected as the SLR period. This decision was made based on the start time (2006) that UBRs closed and alternative Web service discovery and recommendation solutions emerged.
	I3: Studies with proposed solution and evaluation/validation of Web service discovery and recommendation.	We are looking for methods, algorithms, datasets and evaluation metrics using clustering and association rules in Web service discovery and recommendation.
Exclusion	E1: Studies in the form of abstracts, posters, short papers (less than six pages), technical reports, tutorial summary or books.	These studies do not usually provide the information needed for this review.
	E2: Studies that are not in the English language.	Although there are different languages, we excluded non-English studies due to language limitations.
	E3: Studies were Keywords (Web services discovery or clustering or association rules or Web services recommendations) were not addressed explicitly in the article.	We are investigating studies which are related to the research questions. These keywords are needed for screening the primary selected studies.
	E4: Studies that do not include their methods, datasets or validation procedures.	Studies will be eliminated if they do not consider the full-text scanning phase. This is because they will not relate to the research questions.