PERFORMANCE EVALUATION OF JSON AND XML FOR DATA
EXCHANGE IN MOBILE SERVICES
Ivar Jørstad
Ubisafe/New Generation Communication, Bjølsengata 15, NO-0468 Oslo, Norway
Elias Bakken
Department of Informatics, University of Oslo, Gaustadalléen 23, NO-0371, Oslo, Norway
Tor Anders Johansen
Department of Informatics, University of Oslo, Gaustadalléen 23, NO-0371, Oslo, Norway
Keywords: Mobile services, JSON, XML, mobile middleware, AJAX.
Abstract: One of the major challenges of developing mobile services is that of data transfer back and forth between
the mobile device and the server side application parts. This paper provides a performance analysis and
comparison on the use of XML and JSON for data exchange for mobile services. Results obtained from
common emulators are provided, as well as results from live operation on state-of-the-art mobile devices.
1 INTRODUCTION
The future success of advanced mobile services
depends on the ability to seamlessly integrate mobile
application parts with server side components,
similar to how Web-based services and other
distributed services are realised.
This paper provides a study of two different
technologies for data representation when
exchanging data between a mobile application and a
server; eXtensible Markup Language (XML) and
JavaScript Object Notation (JSON).
2 RELATED WORKS
(Arora & Hardy, 2007) introduces an architecture
for mobile AJAX with Java ME technology. The
paper argues that since many existing products
support AJAX in the back-end, it might be sensible
to use also AJAX for mobile applications based on
JavaME as well.
(Zyp, 2008) provides a performance analysis of
Ajax, and shows how to optimize Web-based
applications. The analysis points to areas for
improvements in traditional Web-applications, but
does not consider mobile applications.
(GGGeek, 2007) gives a performance analysis of
different JSON parser libraries for PHP, but it does
not treat the subject with regards to mobile
applications and the client side limitations.
3 PERFORMANCE
EVALUATION
3.1 Goals
The primary goal of this performance evaluation is
to achieve knowledge on the general differences in
performance of using XML or JSON for data
exchange in mobile services.
3.2 Hypothesis
As JSON is a less verbose data representation format
than XML, it is expected that the parsing from JSON
representation into JavaME data structures is less
demanding on the processing and memory
237
Jørstad I., Bakken E. and Anders Johansen T. (2008).
PERFORMANCE EVALUATION OF JSON AND XML FOR DATA EXCHANGE IN MOBILE SERVICES.
In Proceedings of the International Conference on Wireless Information Networks and Systems, pages 237-240
DOI: 10.5220/0002025402370240
Copyright
c
 SciTePress

capabilities of the mobile device, compared to the
parsing of XML. Also, due to the different ways of
representing data structures (e.g. the characters used
to represent boundaries), how hierarchies are
constructed etc., it is expected that there is some
difference in performance.
It is also expected that some usage scenarios
might favour one of the data representation methods,
whereas others might favour the other method.
3.3 Test Framework
A JavaME MIDlet was developed which can request
data from a remote server. The data retrieved is
represented either in XML or JSON. The JSON
library used on the client side was JSON-J2ME
(http://tavon.org/work/JSON-J2ME), and the XML
parser used was the JavaMe port of NanoXML
(http://nanoxml.sourceforge.net/orig/kvm.html),
which is a DOM-style XML parser (i.e., creates an
in-memory representation of the XML document, as
opposed to an event-based parser). For future
studies, other parsers should be included as well.
The test cases used are:
• Parsing of many primitive elements
• Parsing of large elements
• Parsing of deep trees
• Parsing of array elements
3.4 Test Environments
All tests have been performed live on a Nokia N82
running in a MIDP 2.0 environment. The tests have
also been run in the Sun Wireless Toolkit Emulator.
By running in the emulated environment, the
processing capacity and memory of the host device,
and the variations of these according to
unpredictable behaviour of the device, become
closer to irrelevant, and have less influence on the
measurement results.
3.5 Results
3.5.1 Primitive Elements
This test consists of parsing JSON and XML
documents with an increasing number of primitive
elements. The results are seen in Figure 1 and Figure
2. The number of elements ranges from 10 to 5000
with 10 elements interval. All the elements are at the
same (second to top) level of the document. As can
be seen of the graph, there is no large difference in
the time spent processing XML or JSON in this
case. However, when run in the emulator with more
memory and processing power, it is evident that
JSON is performing better than XML. Both for
JSON and XML, the function is close to linear,
where the rate of increase in processing time is
approx. 17.9 for JSON, whereas for XML it is 21.2
(on the device).
3.5.2 Single Element with Increasing Size
This test consists of parsing JSON and XML
documents with one element of increasing size. The
results can be seen in Figure 3 (on device).
These functions are also linear, where the rate of
increase for JSON is close to 2.3, whereas for XML
it is close to 6.7.
3.5.3 Complex Structure/Deep Tree
This test consists of parsing JSON and XML
documents of increasing complexity. The
complexity is introduced by creating a tree of
primitive elements. The results can be seen in Figure
4. The function is in this case exponential for XML,
whereas it is linear for JSON. Running the same
case in the emulator, JSON (with rate of increase in
processing time at 0.37) is not visible in the same
graph as XML.
3.5.4 Array of Elements
The results of this test are seen in Figure 5 (device).
The graphs show that in this case, JSON also scales
much better with increasing size of the data structure
(array size).
3.5.5 Summary of Results and Discussion
In most of the cases used for this performance study,
JSON performs better than XML. Only in the case
with an increasing number of primitive elements is
XML close to the JSON performance, and in the
emulator with “unlimited” resources available JSON
still performs better.
The XML parser used in this analysis is a non-
validating one. It is reasonable to expect that the
difference in performance would be even larger if
JSON had been compared to a validating parser. In
this situation XML does not have any clear
advantages compared to JSON; both can be used to
represent the same type of data structures.
There are other selection criteria than
performance when selecting a data exchange format.
Readability is one. However, XML is marginally
more readable than JSON. There exists fewer
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Figure 1: Increasing number of primitive elements on device.
Figure 2: 100-5000 primitive elements in emulator.
Figure 3: Element size from 1024 bytes to 200 kilobytes on mobile device.
PERFORMANCE EVALUATION OF JSON AND XML FOR DATA EXCHANGE IN MOBILE SERVICES
239

Figure 4: Increasing the tree depth.
Figure 5: Increasing the size of an array from 10 to 1000 elements on the device.
libraries for JSON than for XML, and depending on
the programming language and platform used, this
can dictate the final selection.
4 FUTURE WORK
This study will be extended to cover additional
parsers, native parsers, as well as other changes in
the test input data. It should be interesting to see
how attributes on the XML elements influence the
results.
5 CONCLUSIONS
This paper has provided a study of how JSON and
XML parsers differ in performance on mobile
devices, in particular for services built on the
JavaME platforms. According to different
characteristics of the data transferred between peers
in the distributed system, it is possible to select the
better solution for each situation; there is no
standard answer to which one is the better one, and
the developer should weigh the performance shown
by this paper against other requirements as well.
REFERENCES
Arora, A., Hardy, V., 2007. Mobile Ajax for Java ME
Technology, World Wide Web Consortium (W3C)
GGGeek, 2007. A completely fair and balanced
comparison of php json libraries,
http://gggeek.altervista.org/sw/article_20061113.html
Zyp, K. W., 2008. Ajax performance analysis, IBM
developerWorks, April 24, 2008
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