Seanox XMEX - XML-Micro-Exchange (Free Web Service)

The origin of the project is the desire for an easily accessible place for data exchange on the Internet. Inspired by JSON-Storages the idea of a feature-rich equivalent based on XML, XPath and XSLT was born. The focus should be on a public, volatile and short-term data exchange for (static) web-applications and IoT.

Just exchange data without an own server landscape.
Just exchange data without knowing and managing all clients.

XML-Micro-Exchange is a volatile NoSQL stateless micro datasource for the Internet. It is designed for easy communication and data exchange of web-applications and for IoT or for other Internet-based modules and components. The XML based datasource is volatile and lives through continuous use and expires through inactivity. They are designed for active and near real-time data exchange but not as a real-time capable long-term storage. Compared to a JSON storage, this datasource supports more dynamics, partial data access, data transformation, and volatile short-term storage.

Why all this?

• Static web-applications on different clients want to communicate with each other, e.g. for games, chats and collaboration.
• Smart sensors want to share their data and smart devices want to access this data and also exchange data with each other.
• Clients can establish dynamically volatile networks.

In this communication are all participants.
No one is a server or master, all are equal and no one has to know the other.
All meet without obligation.

Features

• RESTful
  The REST API supports the HTTP methods CONNECT, OPTIONS, GET, POST, PUT, PATCH, DELETE. The CONNECT method is not a standard and the function can be used alternatively via PUT without XPath.
• XPath
  XPath axes and functions are used for access, navigation and addressing of targets in the data source and it is an integral part of the URI with dynamic and functional effects.
• Multiple axes and targets
  An XPath axis can address several elements and attributes simultaneously, which can be changed with one call.
• XPath Functions
  PUT and PATCH support XML structures and static values (text), as well as XPath functions that allow dynamic values.
• Data Query
  Data can be queried in the form of XML structure or substructure if the XPath notation represents an axis, otherwise the XPath is interpreted as an XPath function and responded with the result as text. Thus XPath provides a dynamic syntax for queries.
• Data Transformation
  The POST method supports data transformation via XSLT. Similar to GET, data can be queried and then transformed with an XSLT template transmitted via POST.
• JSON Support
  All requests can be responded by the service in JSON format.
• Security
  This aspect was deliberately considered and implemented here only in a very rudimentary form. The storage name with a length of 1 - 64 characters and the individual root element can be regarded as secret. For further security the approach of Basic Authentication, Digest Access Authentication and/or Server/Client certificates is followed, which is configured outside of the XMEX (XML-Micro-Exchange) at the web server.

API

HTTP is used. The URI typically contains a noticeable separator to divide it into context path and XPath. For the API only the XPath is relevant.

https://xmex.seanox.com/xmex!xpath(-function)
<-------------------------->|<-------------->
        Context Path              XPath
    

In some cases, the XPath syntax may not be supported as a URI by the client or provider. In these cases, the XPath can alternatively be used as Base64 or hexadecimal encoded. For this purpose, a question mark is expected after the last character of the context path and then the encoded string. The encoding method is determined automatically.

https://xmex.seanox.com/xmex!count(//items[@id<0])
https://xmex.seanox.com/xmex!count(%2F%2Fitems[@id<0])
https://xmex.seanox.com/xmex!?636F756E74282F2F6974656D735B4069643C305D29
https://xmex.seanox.com/xmex!?Y291bnQoLy9pdGVtc1tAaWQ8MF0p
    

If the method cannot be determined, the string is interpreted as an XPath (function) and because of the question mark at the beginning usually causes an invalid XPath error.

The request supports the following additional headers:

Also the response has additional headers:

Notice about response code 404: This always refers to the storage file, but never to an addressed target in the storage. If a target does not exist, requests are responded to with code 204 or 304 for modifying requests.

Usage

1. The storage must be opened by CONNECT or PUT without XPath. This can be done by any client, even if the storage already exists. Because CONNECT is not an HTTP standard, it is better to use PUT without XPath.

2. The client should always proceed as if it were using storage alone and created the schema it needs. The creation of the schema is done with PUT. Relative and conditional axes should be used as targets. This ensures that no duplicates are created or data is overwritten.

   e.g. PUT /books[not(book[@title='A Modern Utopia'])]::last

   This approach made transactions unnecessary.

3. Now the client can use the storage.

4. Closing or terminating the storage is not possible and necessary. The storage expires automatically due to inactivity. The duration of use and expiration time of the storage is contained in the response in the headers Storage-Last-Modified, Storage-Expiration, Storage-Expiration-Time.

Free XML-Micro-Exchange

Before using, you must read, understand and agree to Terms of Service and Privacy Policy.

https://xmex.seanox.com/xmex!

65536 Storages x 64 kB
Please do not get confused, the API is online.
Requests without storage identifier are responded with status 400.

It is a small server (1 vCore, 1 GB, 10 RAM GB SSD) in a big datacenter -- but apparently enough.
Sponsors are always welcome.
It costs about 5 Euro per month for 1,000,000 storages x 64 kB with double CPU cores and double memory.

Documentation

• Manual
• Getting Started
• OpenAPI GUI
• OpenAPI YAML

Examples

Multiplayer Snake (Online) Sources

Open Source

• https://github.com/seanox/xml-micro-exchange-php
• https://github.com/seanox/xml-micro-exchange-js
• https://github.com/seanox/xml-micro-exchange-java

About Seanox Software Solutions

Seanox Software Solutions was founded in 2000 as a non-commercial open-source recreational project and it is still that way today. It is pure passion for software development.