SOFTBRIDGE DESIGN STACK 116

The Softbridge stack is a socially aware, or people-oriented, abstraction for the design of ICT4D communication systems (see Figure 8-1). The Softbridge stack extends the 'Big 4' described in Section 3.1 with three additional layers: media, temporality and people. The media and temporality layers are added to include communication application properties into the design stack. The people layer represents connectivity between end-users within the context of their socio-economic and socio-cultural environment. We use RA/RI criteria to explore the people layer to enable the model to reach beyond technology to bridge Heeks' (2002) 'design-reality gap', and achieve an alignment of technical and social considerations. The inclusion of the community is also aligned with the arguments of Best (2003) and Purbo (2005) that the community is the primary source of successful ICT4D projects.

Figure 8-1 Softbridge design stack

The Softbridge stack specifies seven key ICT4D bridges. Power bridges deal with the poor power provision that is common in developing regions. Network bridges involve networking equipment and protocols, usually wireless. A variety of end-user devices can be deployed; mobile devices are particularly useful. Media includes text, voice and video communication, and can be adapted, e.g. text-to-speech. The temporality bridges can be any combination of synchronous, asynchronous and semi-synchronous. User interface bridges are usually linked to media and device characteristics. The ultimate communicating entities are people, not applications. Social influences on the entire process are examined with RA/RI criteria.

The Softbridge stack is not meant to be a replacement for the OSI and TCP/IP models. Rather, the Softbridge and OSI stacks should be viewed as complementary. The OSI stack can be considered a 'drill down' into the Softbridge network layer, as shown in part (a) of Figure 8-2. It is also possible to think of the Softbridge stack as an expansion and extrapolation of the OSI application layer. In this view, the Softbridge stack represents application layer considerations not limited to the network API.

Real Access/Real Impact People Temporality Media Device Network Power Interface People Temporality Media Device Network Power Interface

Figure 8-2 Softbridge stack's relationship to OSI

The Softbridge stack is not meant to be a replacement for the OSI stack for the network programmer. The two stacks should be considered as complimentary. As shown in (a), the OSI stack can be considered a 'drill down' into more detailed internals of the Softbridge network layer. On the other hand, (b) shows how the Softbridge stack can also be construed to include application-oriented considerations for the OSI stack.

The combination of the words 'soft' and 'bridge' are derived as follows. There are bridges between components at respective layers. These bridges may be homogenous or heterogeneous. In a digital divide context, bridges are often between disparate components, e.g. SIMBA v3's bridging between SMS on a cell phone to IM on a PC server to voice on a PSTN handset or VoIP soft phone. SIMBA v3 had heterogeneous bridging at all seven Softbridge layers (see Figure A-14). On the other hand, MUTI prototypes are examples of homogenous bridges with respect to a variety of choices, e.g. provision of text, voice and video media in either real-time or store-and-forward modes. Bridges are considered 'soft' because they are malleable, usually in software.

Softbridge and OSI stacks are very similar structurally and conceptually. Each layer can be considered a 'black box' where components can be swapped in and out based on encapsulation and data hiding. Both Softbridge and OSI stacks hide implementation details for the benefit of designers, as discussed in Section 2.1.1. The virtual bridges between Softbridge layers are conceptually similar to the virtual connectivity between OSI layers (see Figure 2-1). Packet traversal through the OSI stack follows an ordered trajectory. Softbridge layers are also layered according to dependencies. People require a user interface to use an application and the application requires temporalities and media, all of which are implemented on a device that is, in turn, connected to a network, all of which have to be powered. OSI Softbridge People Temporality Media Device Network Power Interface Application Session Transport Network Link Physical Presentation OSI Softbridge People Temporality Media Device Network Power Interface Application Session Transport Network Link Physical Presentation (a) (b)

There are, however, fundamental differences between Softbridge and OSI (or TCP/IP) stacks. Firstly, the communication application is explicitly included in the Softbridge stack in the media and temporality layers. Secondly, people are explicitly included in the Softbridge stack to emphasise socio-cultural relationships to the technical layers. RA/RI criteria considerations affect design choices made at all Softbridge layers and carry design ramifications between and amongst layers. Softbridge characterises how social factors can impact on all of the technical layers. A different view of the stack is shown in Figure 8-3.

Figure 8-3 Intermeshed Softbridge stack layers

Unlike the traditional models, Softbridge layers are very much intermeshed and all layers have some inter-relationship to all other layers via both technical and social considerations. The flower petal arrangement does not restrict interaction with adjacent layers. For example, the poor power in rural environs called for a store and forward approach to temporality. Rather, the arrangement of technical layers around the people layer emphasises the intermeshed nature of Softbridge layers with an emphasis on the people aspects.

For OSI, the parameters and return values of the APIs are the 'leaks' between layers. The leakiness and encapsulation in the Softbridge stack operate differently. The two views of the Softbridge stack convey two complementary approaches to use of the stack for design. Firstly, the layers can be considered stacked as in Figure 8-1 in order to encapsulate and isolate design decisions and implementation within each layer. Secondly, the layers as shown in Figure 8-3 help tease out inter-relationships to better inform the design of each layer in terms of social factors. Thus the Softbridge layers can work differently from the OSI stack layers.

Placing people at the centre of the abstraction explicitly includes the challenging social aspects of ICT4D. The research communities involved with ICT4D advocate such a people- centred approach (Brewer et al., 2005; Deardon et al., 2007; Dray et al., 2003; Thomas et al., 2008a, 2008b; Toyama & Dias, 2008). In order to do this, we use RA/RI criteria to address

Power Network

Device Temporality

Interface Media

the people issues in the Softbridge stack as reported in Sections 6.4.7 and 7.4.7. We often used RA/RI criteria as a checklist and lens to include social issues in ICT4D design. We could manipulate software prototypes in an effort to increase access to ICT, or at least target a prototype at some level of access. For example, SIMBA v3 included SMS as an interface to text relay because many of the participants had already integrated cell phones and SMS into their daily lives. The mobile MUTI v3 prototype was based on very similar reflection concerning handhelds. The nurses already had their own cell phones. The cell phone device for MUTI v3 was much more accessible and appropriate for them than the cumbersome laptop and peripherals of the first two MUTI phases. Thus, the RA/RI criteria of accessibility and appropriateness were designed into communication software prototypes. Successive prototypes became more aligned with social realities via iterative action research, as people layer issues became better understood and designed into prototypes. It follows, then, that RA/RI criteria also feature strongly in evaluation of communication.