Today, mainframes contain a considerable portion of business applications worldwide. It is estimated that the current inventory of production COBOL running on mainframes is 150 to 200 billion lines of code. Despite the efforts to change within the mainframe environment, these mainframes, nowadays, face major problems for host organizations due to a combined set of financial, business related, technical and organizational problems. Moreover, the factors like diminishing resources (COBOL programmers), lack of documentation, inability to integrate with other systems, increasing maintenance costs, etc. have caused the organizations search for migration solutions. To overcome this problem within the context of modernization, over the years several main migration approaches that ranges from simple screen scraping methods to complete re-write of applications or re-hosting of platforms have been developed. To contribute to the solution of this overall problem, this thesis proposes a methodology framework specifically for the COBOL/CICS based mainframes. The research studies in this topic within this field are mainly focused on the technical aspects whereas our concentration is covering not only that but the other essential aspects of the problem domain. These are organizational view, project management view and process view. Within the thesis study, a special interest is given to the modernization strategy selection among migration, rewrite, packaged and do-nothing alternatives. Experimental results are also provided within the thesis to prove the usability of the approach for this selection.

Software as a Service (SaaS) är en metod för att leverera mjukvara där lösningen är centralt lagrad och erbjuden som en tjänst. SaaS erbjuder flera olika fördelar ur både den tekniska och den kommerciella synvinkeln. Som en konsekvens av det är många företag mycket motiverade att flytta sina föråldrade system till SaaS för att fortsätta vara konkurrenskraftiga på marknaden. Tyvärr så är sådana stora migreringar ofta utmanande och problematiska, SaaS lägger till ännu fler utmaningar till den problematiken. Den här studien föreslår en effektiv processmodell för SaaS-migrering när systemen som ska migreras till SaaS är föråldrade. Den föreslagna modellen siktar på att guida SaaS-migreringsprojektet i rätt riktning och därmed utöka sannolikheten för att det skall lyckas. Kvalitativa metoder har använts för att utveckla och validera modellen. Den initiala modellen utvecklades från experimentiell kunskap i kombination med att studera och analysera relevant arbete i området. Modellen modifierades iterativt ytterligare genom att konsultera både akademiska och industri-experter med relaterad bakgrund. Slutligen så valdes experted på ämnet ut och öppna intervjuer genomfördes för att validera modellen. Resultaten från intervjuerna föreslår att den föreslagna process-modellen är väl anpassad för att appliceras i industrin och förväntas kunna hjälpa en organisation att genomföra SaaS-migreringsprojekt effektivt och framgångsrikt. / Software as a Service (SaaS) is a software delivery method in which software is centrally hosted and offered as a commodity. SaaS provides numerous advantages both from technical and business perspective. Hence, many companies are highly motivated to move their legacy systems to the SaaS in order to stay competitive in the market. However, any migration of legacy systems is usually challenging and failure prone. SaaS migration adds more challenges on top of that. This thesis proposes an effective SaaS migration process model for migrating legacy application to SaaS. Proposed process model aims to guide the SaaS migration projects in the right direction and thus increase the success rate. Qualitative method was used to develop and validate our model. The initial SaaS migration process model was developed from experimental knowledge in combination with studying and analysing relevant work in this field. The model was further modified in iteration by consulting both academic and industry experts with related background. Finally, experts were selected on the subject matter and conducted structured open-ended interviews to validate the model. The interview results suggest that the proposed process model is well suited to be applied in industry and is largely expected to help an organization to drive the SaaS migration project effectively and successfully.