I won’t repeat any definitions of what NoSQL databases are, nor a review of any specific products. I’ve read plenty about NoSQL databases and I think that the general view of developers is that it is one more tool in the arsenal of application development. I generally believe that you should choose the right tool for the job at hand. So, you may get that task one day where the advantages of using a NoSQL database outweigh the disadvantages. Can, or how can you use this database with Uniface? The answer definitely depends on the specific NoSQL database product. Between them all, they have a large variation in their APIs and data structures. For that reason I will just describe my experiences doing some prototyping with CouchDB from Apache. Be aware that this is slightly different to Couchbase, which appears to be a commercialised offshoot from what Apache took on board as an open source project. For brevity, I refer you to the website for information about CouchDB’s characteristics: https://couchdb.apache.org/ The major characteristic of CouchDB is that the documents stored in the database are in JSON format. While investigating another project, I stumbled upon a convenient source of JSON formatted documents that I could use to store in my CouchDB database. I hope that you aren’t offended by simple Chuck Norris jokes. It is a unique genre that not all will enjoy, but it served my purposes adequately. Thus in studying my prototype, you could imagine how you would handle more business related data. I have provided a sample form in the community samples part of Uniface.info. All you need to do, besides compiling that one form, is to download and install CouchDB from the earlier link provided. I downloaded the Windows version. I manually created the “cnjokes” database using the CouchDB provided Futon utility, also installed with the Couch DB. I also manually defined the design document “vcnjokes”; more about that later. The top part of the COUCHTEST01 form is really a “utility” area, where you can manually enter URIs and run requests against the “cnjokes” database. These requests use the UHTTP internal Uniface component. The way the CouchDB API is structured gives you a very RESTful web service interface, though there are some comments on how RESTful CouchDB really is, within their online tutorials. The results of the calls are available in the message frame. You can press the GET button without adding anything to the URI and you will see some global information about the “cnjokes” database. Overall, this “utility” is not as flexible as the CouchDB provided Futon utility, but it might be helpful during further Uniface development. The 4 buttons, and accompanying entity and fields provide the real prototype; effectively demonstrating a CRUD lifecycle of managing CouchDB documents. The UHTTP component is used to obtain a CN joke in JSON format from an internet website, and then the UHTTP component is used to interact with the localhost CouchDB server. The document format is deliberately unchanged between the external joke website and CouchDB. However, you could manipulate the JSON before storing it in CouchDB if required, using Structs. Note that I have used $uuid as the basis for assigning a document ID. The other 3 buttons query the CouchDB database using views. Ad-hoc queries are not possible in CouchDB. The 3 views are defined in a single “design document” called “vcnjokes”. The source for that design document are provided with the sample download, as comments for the COUCHTEST01 form.
- Button “Get all current jokes from CouchDB” uses view "joke_by_jokeid". All jokes are retrieved, and sorted by joke_ID, but only a few columns are selected. It cannot be edited as the revision ID is not available. Note that escaped quotation symbols in the data are displayed as quotations.
- Button “Get all nerdy jokes from CouchDB” uses view "nerdy_joke". The jokes list is filtered to those that have a category of “nerdy”. This list also cannot be edited.
- Button “Get all current data from CouchDB for edit” uses view “all”. This view references all of the document and so all fields, including revision ID, are available. Thus editing can be done, and when stored, the new revision number is updated. Note that escaped quotation symbols appear as stored, for ease of updating.
When preparing the JSON for display in a Uniface form, it is certainly necessary to use Structs to manipulate it into the Component data structure. In fact the choice of the external data structure of the form entities is quite arbitrary. CouchDB has no fixed schema. Thus you can never be sure that an external application won’t add data that renders your entities and fields obsolete. All I could do is generate a useful number of jokes, and observe that some of them have one category with a value of “nerdy”. However, I can see that the category is defined as a JSON array, and so I make sure to set $tags->jsonClass = "array" before converting the struct to a JSON string. This is what led to the one to many relationship between CNJOKE and JCATEGORY. With my CouchDB data set, I verified my schema by manually adding several extra categories to some jokes, using structure editor commands to add and remove occurrences (tool tip text will assist you). Hopefully this prototype demonstrates how modern features in Uniface allow integration with other modern software systems.
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