There are a lot of free web services or web applications being offered on the web. Whether it is something like mail, maps or communications, these services often meet or exceed personal users requirements. But how about for business use? Is it something that should be added to your product?
First of all, read the fine print. Find out if you are allowed to use the service from a business or for business purposes. We aren't talking about re-branding Google Maps to "My Company Maps" entirely, which is obviously forbidden in the Google terms of use (And every other mapping product's terms of use, of course). For the purposes of this article, let's assume we are talking about your business adding significant value to the service. Most public services allow business accesses, but have certain restrictions on number of accesses per day, or size of storage, or something like that. If the terms meet your needs, remember that they can be changed at any time and that you don't have a permanent right to use their services.
Before you begin any new project around a particular service, you next want to impose some restrictions and drive development in a proper manner. Make the service as modular as possible. Instead of hard-coding something to do a lookup with one provider's service only, abstract it enough that you can later field-replace the component should the service be taken down, or allow the configuration in the software. It is important to ensure that you also monitor the terms of service for the connection to ensure it hasn't changed or to ensure that you or your customers haven't been blocked. In some circumstances, it may be better or mandatory to have the requests hit your public server and then you drive the connections solely to the public service. This redirection may allow you to cache data, re-deploy it in another format, but most importantly it allows you to keep statistics to ensure you aren't exceeding the public services terms of use.
Remember also the rule of change. Things change, always. If we talk about mapping software, the providers constantly try to add new features, become higher resolution or something like that. The law also may have an effect, for example, Google maps has to blur faces. If your software relied on previous features that suddenly change or completely disappear, you have no recourse and just have to redevelop if you want to keep your products on-line and providing value.
And what if the service is wrong? What if you ask for a temperature conversion and retrieve an obviously wrong value? Does your business need to have accuracy or you have to support those errors? Most of these companies have support for their on-line services, and have invested interests in fixing problems. Some may only have a window of repair for their next release and you will have to suffer through. Make sure you have a way to deal with things that they publish that you cannot control.
Can you disclaim this in your software? I have heard of people adding exclusions in their service agreements for products that state something to the effect of "uses components of xxx public product, which has its own terms and conditions that you also must abide by." However, if your product is 90% xxx public product, and only 10% stuff you added, you really haven't sold a workable product when the public product is taken down. Since your product disintegrates, you may have to (by law!) replace the cost of the product for your users.
Is it valuable then to use these services in the long term? We think so. At least in the "here and now". Most companies offering public services track usage. The more the public use it, generally, the more they provide in terms of support and features. Only if economic conditions or something drastic occurs will the plug be pulled. And remember, that plug will effect tens of millions of other users, too.