JSON and XML are two language-independent data formats which are frequently used in coding for software and mobile app development. We have here done a point-by-point comparison analysis of the two tools.
Among app developers (web and mobile), JSON has emerged as the most preferred language tool for interchanging data. The surge in the popularity of JSON (Javascript Object Notation) has come at the expense of the user-base of XML (Extensible Markup Language). Most users cite the greater user-friendliness of JSON as the key cause for it being able to trump XML. In here, we examine whether JSON is indeed better than XML, on the basis of some key attributes:
- The learning curve – For newbies to the field of coding for app development, both XML and JSON are equally simple. XML is definitely an easier language than SGML – but JSON might just have an edge, owing to its direct mapping feature on data structures. The smaller grammar and syntax set of JSON helps on this count too. However, there is not much of a difference – a certain time and effort has to be invested to learn either of the data marshalling tools.
- Need for manual typing – JSON holds all the aces in this regard. Many software programming experts and mobile app developers have referred to XML as a ‘verbose’ language – while brevity is the name of the game in JSON. Two sets of code of equal size (in terms of bytes) can be written using much fewer characters in JSON than it can be done in XML. The host of start and end tags required in XML contribute to its elaborateness. Although most data servers do compress data sets (via gzip or other tools) before sharing, the fat-free nature of JSON finds more favor among users.
- Extensible feature – This round goes to XML. The language supports a wide range of data types, while with JSON, all that developers can work with are numbers and text. Extending the data attributes in XML is fairly easy, although it is advisable to not store too many data types in a single data set (managing the set might become an issue in such cases). Of course, since JSON is not meant to be used as a document markup language per se, the need for including additional data types often does not arise.
- Use of Arrays – Coders have to work with ‘arrays’ only while working with JSON. While describing structured data in XML, there is no concept of array usage. There is, hence, just that extra need for software and app developers using JSON to be careful about declaring and managing the ‘arrays’ in their programs. Not properly defining the data arrays generally lead to errors being generated.
- Parsing (Server-side) – XML parsing capabilities are built-in in practically all popular server-side frameworks. Via parsing, an object model is created from the original text format. However, with the rapid popularity of JSON, most new servers are including parsing capabilities for it too. The function is similar to that of XML parsing, and there is no significant difference between the speed or accuracy of JSON and XML parsing. Fair to say, it is a tie between the two data formats on this count.
- Readability – Just a while earlier, we highlighted how XML was more extensible than JSON. While the latter is relatively more restrictive, the smaller range of data sets/formats supported by JSON has a definite advantage – it is more easily readable and understandable by programmers and mobile app development experts. XML offers much wider options for data formatting, which makes universal standardization of data slightly difficult. There is no such potential issue with JSON – simply because the formatting options are limited here. Both the formats use Unicode, which ensures data internationalization.
- Speed and memory usage – Another point where JSON comes up tops. Less characters have to be typed in JSON compared to XML, and browser-side parsing with the latter can be time-consuming (particularly if you are working with a large dataset). The DOM manipulation libraries required for XML parsing can take up fairly large memory spaces too. The sheer compactness of JSON ensures that it is faster (although not by much), and memory requirement is minimal.
- Data Querying – While coding for apps or any other software, developers often need to access/refer to certain parts of data that they had used earlier in their programs. Doing so in JSON is rather problematic, particularly if the exact location of that data is not known. The entire code has to be reiterated, to find out that piece of code. XML-users have a big advantage here, thanks to the presence of XPath. The latter allows users to directly access data in any specific part of the code. The lack of a dedicated querying interface in JSON is certainly a drawback.
- Sharing – This is where the basic difference in the nature of JSON and XML comes to the fore. Since the latter is a dedicated document markup language, it offers support for quick and seamless sharing of data graphs, pictures, charts, figures, and many other data types. The format or prototype of the data (in addition to the actual stored data) can also be shared. JSON, on the other hand, is a data markup tool, and really shines through when it comes to exporting/sharing array data. Irrespective of whether you are coding in Perl, Python or Javascript, it is easy to import JSON files without any risk of data loss. Traditional data is stored in ‘trees’ on XML (as opposed to ‘arrays’ in JSON), and it has to be transformed first, before sharing. The process is more cumbersome.
- Parsing (Browser-side) – Not every browser supports E4X (ECMA for XML), and this makes XML parsing on the browser-side stand on shaky grounds. The memory-related disadvantages of DOM documents have already been mentioned, and experts from the field of data management and app development opine that native Javascript files are easier to handle than these DOM documents. On its part, JSON does not have a parser. The eval () function is used to interpret JSON syntax (stored within the parent Javascript Syntax). Evaluation of JSON strings can be done with the same function as well.
- Tagging and validation – JSON does not have any feature comparable to XML schema, and hence, cannot be used for validation. In other words, if data validation is required in your work, using XML will probably be more advisable. Yet another advantage of XML is the option of tagging or using markup on text documents. The XSLT template can be used in XML to change the original data format (to text, SVG, comma-delimited or HTML). In fact, converting to JSON format with XSLT is also possible. In terms of flexibility and customization, XML does hold an edge.
- Representation as code objects – Software programmers and app developers generally work with dynamic, object-oriented languages which support easy representation of JSON objects as objects in the code. On the other hand, porting XML objects to the code can lead to alignment issues, since there are more data formatting options and greater scopes of interpretation and data representation. It is true that JSON ‘prohibits’ developers somewhat, but it is also a more easily usable language. In a nutshell, JSON is intuitive, XML is not.
- Parsing security – Parsing JSON data with eval () is easy and quick, but it can be risky as well. If an invalid JSON file is passed through the function (even if the Javascript code within is valid), the code gets executed, and the entire application can get messed up. The problem arises from the fact that any Javascript code gets automatically executed by the eval (). XML parsing is slower and requires more memory – but at least it does not involve any risk of erroneous code execution.
- Compatibility with different file formats – From plain text and pictures, to video and audio – files in practically any format can be attached with XML. JSON, on the other hand, is all about only the traditional file formats. This ‘limitation’ of JSON does, however, have an advantage – there is no way of including executable files in JSON, which can cause security concerns. Both the data marshalling tools are equally open and have proper self-describing features.
The above analysis indicates that, while JSON is definitely better than XML on certain grounds, the latter has its high points. Many of the apparent advantages of either tool are rather muddled too – since they come with potential risks (for instance, XML is extensible, supports more data types, but is heavier and can be confusing). The key here for web and mobile app developers is to understand that the two data formats are optimized for different things – JSON for data, and XML for documents. Another interesting point is that, most of JSON’s advantages are from the browser-side – the server-side is more or less a level-playing field.
Which one do you think is more efficient – JSON or XML?
Hussain Fakhruddin
CEO at Teknowledge Software
Hussain Fakhruddin is the founder/CEO of Teknowledge mobile apps company. He heads a large team of app developers, and has overseen the creation of nearly 600 applications. Apart from app development, his interests include reading, traveling and online blogging.
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