Monitoring interruption on Apr 23rd 2015

Our monitoring network experienced a service interruption on Apr 23rd 2015 from 9:20 to 10:40 UTC. No monitoring data was collected during this time. During this interruption Spatineo Monitor and Spatineo Performance were accessible and usable, but users were unable to configure services or meters and it was not possible to add new services for monitoring. This interruption was caused by malfunction in crucial services provided to us by Amazon Web Services. We noticed this malfunction right as it begun and reacted to the developing situation as quickly as possible. Monitoring was resumed immediately after the services were fixed.

Monitoring is now operating nominally and we are keeping a close eye on the situation. We apologize for any inconvenience caused by this interruption.

Identifying requests from Spatineo

Spatineo monitors a large amount of web services, and most of these services are publicly available over the internet. Monitoring works in a completely automated fashion in typical cases. In some cases though, our customers are interested in identifying which requests originate from our monitoring. For example some services may require authorization using HTTP authentication, User-Agent filtering or IP address white lists.

HTTP authentication

HTTP Basic Authentication is widely used in OGC as well as with other web service protocols. As the name says, it is very basic and it is not ideal or the most secure authentication method available, but it is supported by almost all HTTP clients and servers and, despite the valid criticism, it still has its uses. If you combine Basic Authentication with a properly secured HTTPS transport, it is still a relatively good authentication method. Even without HTTPS, it does give the service provider more control over their service for example, to block offenders if irregularities arise.

Users of Spatineo Monitor may set up the basic authentication parameters used when we send requests to their service via service parameter configuration. These parameters are used for retrieving service descriptions, monitoring requests and performance tests.

In addition to HTTP Basic Authentication, our customers can configure extra query parameters or HTTP request headers that will be sent on every request.

User Agent

All monitoring requests use the HTTP User-Agent request header to tell the server that the request is coming from Spatineo. This is the most precise way of knowing which requests are sent by us. For monitoring requests, the User Agent also contains a link to the Spatineo Directory page of the monitored service. Please keep in mind however that the User-Agent identifiers we use are well known and as such, are unreliable for authentication.

The User-Agent for querying for new services or updating previously known services is:

Spatineo Monitor Controller (

The following User-Agent is used for monitoring requests (where NNN is the ID for this particular service):

Spatineo Monitor GetMapBot (; MonitoredService

Spatineo Performance uses this User-Agent for requests sent during performance tests:

Spatineo Performance (

User-Agent information is also helpful if you wish to allow or block monitoring from us by using the robots.txt mechanism.

Source IP

The Spatineo monitoring network is comprised of multiple servers running in multiple data centers. Monitoring requests, performance tests and service discovery all come from different IP addresses. We keep an up to date list of the IP addresses used by monitoring and service discovery which is available at The list is automatically updated when IP addresses are added or removed from the list.

Please keep in mind that this list does not include the IP addresses that Spatineo Performance tests originate from.

Opening the INSPIRE conformance testing

Our CTO Ilkka Rinne was selected as the facilitator of the workshop on INSPIRE validation and conformity held in Ispra, Italy in early December 2014. In this post he describes some of the issues they were (and still are) working with, how he sees the future of the INSPIRE conformance testing based on Open Source code and community involvement.


A misty view from the Hotel Lido in Angera over the Lago Maggiore. At this time of year the breakfast was the time to take photos, after the workshop day it was already too dark.

INSPIRE conformance, what does that mean exactly?

EU INSPIRE directive is at the centre the multi-national activity for building a Europe-wide Spatial Data Infrastructure (SDI): a network of online Spatial Web Services providing spatial data collected by public authorities in all EU member states. The aim is to be able to find and fetch data from mineral resources to up-to-date weather conditions, and administrative borders to animal species distribution on-demand from directly from the authorities collecting them.

The INSPIRE directive mandates the public authorities to publish their data sets in harmonised formats using standard web services. The data users including other public authorities, research institutes, private companies and citizens are able to use same software products for viewing and downloading the INSPIRE data sets from any member state. According the INSPIRE vision it should be easy to compare these data sets and use them as up-to-date input data for all kinds of applications and decision making processes.

The seamless INSPIRE data-sharing vision does not turn into reality without formal regulation and technical guidance on the data content, metadata, formats and service interfaces to use within the technical INSPIRE infrastructure. Fortunately there are already good general data and service standards in the field of Spatial Data that can be adopted for the INSPIRE use provided by well-known standardisation organisations like ISO and the OGC. These standards provide a solid base for technical interoperability on which the INSPIRE SDI can be built on.

The INSPIRE specific requirements for datasets and services, as well as the metadata records describing them, are given in INSPIRE Implementing Rules (IR) and their corresponding Technical Guidance documents (TG). The IRs are published as part of the EU legal regulation (directives), to be implemented as national laws in the EU member states. The TGs are not legal text, but provide a help and working examples for technical solutions the member states can use to abide to the IR legal requirements.

An EU member state may conform to the INSPIRE regulation using one of the options outlined by the Technical Guidance documents or in any other means, provided that it can show that this alternative method still fulfils the IR legal requirements. The later approach is generally not recommended because it’s likely to cause technical interoperability problems between the data exchange between the member states. However, it would also be problematic to bind a particular technical solution to the inevitably slow process of the EU-wide legal regulation system: It’s a lot simpler to keep a technical document up-to-date if every change does not have to be ratified in the parliaments of 28 countries.

The downside of having two levels of requirements is that the term “INSPIRE conformance” is bit tricky to define: Does that mean that the IR (legal) rules are fulfilled? Or that the requirements in a particular Technical Guidance are fulfilled? These questions and harmonising the results existing INSPIRE validator software solutions used in different member states are in core focus of the INSPIRE Maintenance and Implementation Group (MIG) activity MIWP-5: Validation and conformity testing.

A workshop with a clear focus

One part of the MIWP-5 activities is analysing the requirements written down in the current TG documents and trying to formalise tests for validating services, datasets and metadata records against these requirements. I’m the facilitator of the small and active group of people currently working with this subtask. Last week on 2nd and 3rd December 2014 we had a two-day workshop on this matter kindly hosted by the JRC Institute for Environment and Sustainability which is part of the European Commission’s research facilities in Ispra, Italy.

From the total of 208 requirements in the Technical Guidance documents for INSPIRE Metadata, View and Download Services we chose to focus on the ones considering metadata, view service implemented using the OGC Web Map Service and the file-based download service option implemented using Atom feeds. Even with this limited focus we had almost 160 requirements on our plates – more than enough for two workshop days.

The main task as to define Abstract Test Suites (ATS) for each of the implementation options. These sets of natural language test case descriptions will then act as functional requirements for validation testing programs, or Executable Test Suites (ETS), which form the core of the validator software implementations for INSPIRE conformance testing. The Technical Guidance documents also contain a number of requirements for which it is very difficult, if not impossible to formulate a mechanical pass/fail test: Sometimes it takes a human expert or external knowledge to assert if the requirements are fulfilled or not. This is completely ok, but for making automatic validation tools it’s important to separate the two. Passing a mechanical validator can never guarantee a 100% conformance, but a good validator can help the work considerably by helping in spotting many common errors.

Schematic on relations of INSPIRE IR and TG requirements and the Abstract and Executable tests. CC stands for Conformance Class.

Schematic on relations of INSPIRE IR and TG requirements and the Abstract and Executable tests. “CC” stands for conformance class.


I’m glad to say that we made good progress with the work in these two days: We agreed on the format for the Abstract Tests, had very good discussions around the challenges in some of the TG requirements and the ways to work around them, and decided on the next steps and dead-lines for finishing the work.

Increased transparency with Open Source validation code

Validation rules and techniques used for evaluating the official INSPIRE conformance must the be transparent. If a validation fails for some input it must be possible to check how the validator code has been implemented. As in any software product there will be bugs and certain inputs that will result on false validation statements. In order to spot these weaknesses and make the validation code better in time, we strongly support the idea of publishing both the Abstract Test Suites and at least the officially endorsed validator implementations as Open Source projects.

I believe that the fact that code and it’s functional requirements are openly available and easily extendable, is a key to the INSPIRE conformance testing success. Only by being open and getting the developer community involved in the process can we get keep the testing codebase continuously up-to-date. By carefully choosing the licenses used we can create living and continuously improving shared validation codebase and still make it feasible for companies like us at Spatineo to create additional value for our users by focusing on thing like usability and integration with our other products.

As any successful Open Source project the INSPIRE validation projects also need clear governance and change management processes. It must be clear which versions, forks and branches are officially endorsed by the project leads. For INSPIRE the obvious authority for approving the ATS and validator library code changes would be the MIG. In practise the work of filtering and consolidating the code change proposals, preparing the changes for MIG approval, and creating the official releases would have to be done by some kind of expert board, the members preferably chosen amongst the top contributors but also having some technically oriented MIG representatives to guide the direction of the work.

As one result of the workshop we have now have set up public ATS repositories at Github under organisation inspire-eu-validation. While writing this the ATS drafting is still in it’s early stages, but the content will add up as we approach the February 2015 dead-line. The ATS texts are published in Public Domain using Creative Commons CC0 1.0 Universal license. The license used for the executable validation code has not yet been decided, but I’m pretty confident that it will allow the code to be used as a software library in both open source and closed source applications.

Spatineo will be contributing both design time and our expertise in the INSPIRE & OGC validation to these ATS and ETS projects. You may ask what is Spatineo getting out of participating in this work? The answer is that with Open Sourcing of the validation logic we can focus our development resources for keeping the usability of INSPIRE validation tools top-notch while still ensuring that we can always provide the officially endorsed validation results to our customers. Making Spatial Data Infrastructures “tick” is what we do at Spatineo. Being able to build more reliable tools for validation is an important part of that work.

INSPIRE Workshop: Practical Quality Assurance of Spatial Web Services

We’re doing a lot in in this year’s INSPIRE conference in Aalborg, Denmark. Our R&D Director Sampo Savolainen is talking about “Performance Testing of INSPIRE and OGC Services” in “Quality and Testing” parallel session at 9:15 on Thursday in “Room: 5 Radiosalen” and our Service Director Jaana Mäkelä about “Open Data and INSPIRE Web Services Are Available – Are Users Ready to Utilize Them?” in parallel session “INSPIRE Benefits Usage and Users” at 14:30 also on Thursday in “Room: 3 Latinestuen”.

We’re proud to be a bronze sponsor for the conference and also have a Spatineo stand in the conference centre during the actual conference days from Wednesday to Friday. Come visit and learn more about how we can supercharge your SDI.

See the conference venues on a map

My biggest personal effort for the conference this year is a workshop on Tuesday morning. You’re most welcome to join if you’re coming to the INSPIRE Conference 2014 in Aalborg.

Practical Quality Assurance of Spatial Web Services

INSPIRE Conference 17th June 2014 at 9:00 – 13:00 (two sessions),

Aalborg University, Badstuestræde 9/auditorium 1

Hosted by CTO Ilkka Rinne & Managing Director Kristian Jaakkola from Spatineo Inc.

aalborg legoland By flicrk user Alan Lam

aalborg legoland By flicrk user Alan Lam

Preliminary workshop schedule:

Session 1: INSPIRE Quality of Service

Presentation: Overview of the INSPIRE QoS requirements for Network Services

Group discussions, topics:

  • INSPIRE QoS requirements: Difficult or easy to achieve? Useful or not?
  • How to make improving QoS worthwhile and simple for the data providers?
  • Application developer perspective: What QoS indicators would be most useful for the data users? How they should be advertised for INSPIRE services?
  • Planning for QoS: How to integrate QoS measuring and improvements to a daily / monthly / yearly development plans & practices?

Demo: Evaluating the Spatial Web Service availability and continuous performance with Spatineo Monitor

Session 2: Hands-on Spatineo QoS Tools

Hands-on training: Spatineo Monitor

  • Finding and monitoring new services
  • Checking availability, alerts & maintenance breaks
  • Usage analytics & reporting

Live capacity testing session using Spatineo Performance

Workshop wrap-up & discussion

Update: the workshop slides are now available in Slideshare.

Kickstart for automating the INSPIRE Monitoring

What we typically mean by monitoring at Spatineo is quite different from the INSPIRE monitoring. Our monitoring is continuous technical surveillance of the spatial web services to evaluate their availability and responsiveness. In the INSPIRE sense monitoring usually means the yearly process of collecting and reporting a set of numerical indicators for following the progress of the INSPIRE directive in EU member states. Both activities are important for building a reliable European Spatial Data Infrastructure, and we’re happy to be able to help our customers in calculating some of the most laborious indictors such as the usage statistics by services and data sets.

Making the INSPIRE monitoring easier and more useful is one of problems to be tackled within the work of the INSPIRE Maintenance and Implementation Group (MIG), and specifically in it’s subgroup called MIWP-16 in which I’m one of the 30 members. The group had it’s first face-to-face meeting in a very nice Italian town Arona by the beautiful Lago Maggiore on Friday 11th April. In this blog post I’m giving you my personal view of the work we’re doing and how we could reach the goals set for the group’s work.

Carousel on the Arona town square

Carousel on the Arona town square

In many EU member states the collection data for the monitoring indicators requires a lot of manual work both for the government and local authorities. For example a great part of INSPIRE data providers currently lack the technical means for automatically creating precise usage statistics for the services they are providing. In many cases calculating these yearly figures takes a considerable amount of time, and with the decreasing governmental organisation budgets, it’s in many cases considered infeasible altogether. The obviously results in decrease in the quality and coverage of submitted indicator data, which in turn limits the usability of this data in further analysis and strategic planning at EU level.

The main objective of the MIG work package MIWP-16 is to reduce the amount of manual work for collecting, analysing and submitting the monitoring indicator data required for the INSPIRE monitoring reports sent by each EU member state to the European Commission each year. These indicators are designed to reflecting the progress and successfulness of INSPIRE implementation in EU member states, such as the numbers of available INSPIRE compliant data sets, web services for accessing and usage statistics for those services and data sets. These indicators have been listed in the INSPIRE Implementation Rule for Monitoring and Reporting, and thus each member state is legally mandated to collect them. In addition to streamlining the data collection process, a web dashboard tool with the outlook for the collected monitoring indicators and their yearly trends is also in the to-do list for this work package.

Scene along the shoreline towards the Arona town square

Scene along the Lago Maggiore shoreline towards the Arona town square

The working group of voluntaries consist of both people working directly with the INSPIRE monitoring in the member states and other INSPIRE experts interested in the monitoring and reporting. We are tasked to come up with ideas and design of technical tools for making the monitoring indicator collection more automatic for the member states. One of the essential ideas is to reuse the information already available in the so called discovery services containing machine-readable metadata records for each the INSPIRE data sets and services. As each member state is mandated to provide and maintain these metadata web services, it’s a natural idea to use the information there as an input in automating the calculation of the monitoring indicators.

For some indicators such as the amounts and names of the available INSPIRE data sets and services the process of information extraction is relatively simple, because of the standards-based querying capabilities of these services. The Catalog Service for Web (CSW) interface standardised by the Open Geospatial Consortium (OGC) allows filtering of the returned metadata records based on the properties they contain, such as the type the the described (data set or service) and the declared compliance of those resources against the INSPIRE regulations. It should be noted that the metadata-extracted numbers can only show numbers for the resource that have INSPIRE-compliant metadata records available via a CSW interface. This is not yet the case for all available INSPIRE data sets and services in all member states. For other indicators, such as the usage statistics, this approach cannot be used, as the information for calculating them is not available in the metadata records.

Yes, we did some work too...

Yes, we did some work too…

As of mid-April 2014 our process of designing the mentioned automating tools is still in it’s very early phases. As I mentioned before, this meeting in Arona was the first face-to-face meeting of the MIWP-16 group after a series if bi-monthly web/teleconferences since setting up the group in late December 2013. The group has executed a web-based questionnaire targeted to the people working with the INSPIRE monitoring and reporting on the national level. The received answers from the 14 member states provide a good guidance for the perceived importance for the different indicators from the member state’s perspective and their desires in having those indicators included in the monitoring dashboard. After this meeting we are in the phase of drafting the functionality of the dashboard and the technical architecture of the data collection system providing the data for the dashboard application.

Flying over the Alps

Flying over the Alps

During my flights home over the snow covered Alps and cloudy Central-Europe I draw a high-level draft of a diagram for the information processing system required for the monitoring indicator automation tool based on the group discussion. The system should allow complementing the information retrieved from the metadata records from external sources, like dataset/service validators, usage statistics calculators etc. One option for providing this information would be an authenticated API with a reasonable simple, general enough data model that these external systems could use to submit the complimentary data. The automatically calculated monitoring indicators would then be reviewed by the reporting authorities and manually corrected if necessary. The output of the tool could be published in the monitoring dashboard and/or exported as the pre-filled spreadsheet or XML document to be used in the official INSPIRE monitoring.

Overview of the indicator automation process

It seems to be commonly agreed that the resulting software should not be created having only the EU level monitoring in mind. It should be possible to install the tool set also by member state authorities for helping the INSPIRE monitoring at national and local levels. Technically this would mean ability to connect to any CSW service for extracting INSPIRE metadata records, not just the INSPIRE Geoportal. It would also be natural to build the system flexible enough to allow adding and changing the set of indicators for each reporting period to fit the slightly diversifying needs of monitoring at all levels for years to come. Licensing the software as Open Source would also seem to me like a good fit for making the continuous non-centralised development possible. I should remind the readers that these ideas at least at this stage are my own, and not a commonly agreed position of the MIWP-16 group.

Coming from the background of user software design, I must admit that the goals of the work package seem quite ambitious, especially considering the given time frame (a prototype of the dashboard by the INSPIRE conference in June 2014, about 2 months from now, and the final results by the end of the year). It does not exactly help that the most of the working group members are able to dedicate only a fraction of the work time for the project and no other resources (for example for UI design and implementation) are currently foreseen. Personally I’m already quite occupied with making the first release of Spatineo Performance happen before summer as well as in helping Finnish Meteorological Institute in releasing more interesting meteorological information as open data. Nevertheless I’m confident that with good project leadership it’s possible to achieve good results in drafting the required functionalities based on the most important use cases for the dashboard and the report automation even with the limited time and resources.

Borromea castle in Angera as seen from Arona side in the lake

Borromea castle in Angera as seen from Arona side in the lake

Following the principles of openness and transparency of the INSPIRE maintenance and implementation work, the workspace of the MIWP-16 group is publicly available as a Redmine site hosted by the JRC. Most of the group material, including the accepted minutes of the web and face-to-face meetings are provided for anyone. Internal discussion of the group members and tasking is kept private to make the internal communication as efficient as possible.

If you have any comments or ideas about this work, please comment on this post or send me an email. I’d be glad to pass them on to the working group members for discussion.

Further information:

The new Spatineo YouTube channel

This is just a quick notice that we’ve launched a new Spatineo channel ( on YouTube. The channel mainly features videos about our products Spatineo Monitor, Spatineo Directory and the upcoming Spatineo Performance, but also some selected highlights of Spatineo related events.

We previously had a YouTube channel at, which is no no longer available, but all the videos have been transferred to the new channel. Creating the new channel was unfortunately necessary to associate it with our Google+ page and better organize our appearance in social media. While doing the changes, I also took the opportunity to do some face lifting of the channel visual appearance.

The next in line for the channel are a couple of “User manual” videos covering some of the most typical usage scenarios of Spatineo Monitor. It would also be interesting to experiment with Hangouts On Air to discuss with you about our products and answer any questions you might have. Let’s see how that works out, so stay tuned.

Robots exclusion and Spatineo

Robots.txt refers to the file name specified in the unofficial robots exclusion “standard”. This is used to inform automatic web crawlers which parts of a server should not crawled. You can also specify different rules for different crawlers. This standard is not a technical barrier for crawlers but a gentlemen’s agreement that automated processes should, and generally do respect.

A website may define robots exclusion information by publishing a robots.txt in the root path of the service. For example is the exclusion information for our website.

More on this specification can be found on

Spatineo Monitor

Spatineo Monitor adheres to the exclusion rules and thus, does not monitor web services that are disallowed via this mechanism. Spatineo however does load service descriptions despite robots.txt in the following cases, where we think it is nevertheless appropriate.

  • A user may request to update or add a service to our registry. This is an user-initiated operation and thus robots.txt does not apply to this situation.
  • We attempt to update every service once per week. This is because we want to avoid Spatineo Directory containing outdated or incorrect information about other service providers (you, perhaps?). One request per week should not cause performance issues for anyone.

“Why is there no availability information for my service?”

It is common practice for IT maintenance to disallow all crawling for web services. This is usually done by having a catch-all disallow-all robots.txt on the server in question. This is done to avoid generic web crawlers from inadvertently causing load peaks and performance issues on the servers. While it is true, that typical search engine spiders will usually only be confused by web service descriptions and operations, Spatineo Monitor is created specifically to understand these services. As such, allowing Spatineo to crawl the service will not cause performance issues.

We recommend you make sure that your current robots.txt is truly appropriate for your server. Broad exclusion of crawlers will mean that your users may never find interesting information you have published on the server. Generally, when you publish something online, you want that to be found.

The easiest change (besides completely removing robots.txt) you can make to allow Spatineo Monitoring is to add the following lines in your robots.txt, before all other content:

User-agent: spatineo
Allow: /

Please note that both “User-agent” and “spatineo” here are case sensitive.

“I want you to stop monitoring my service”

If monitoring is causing performance issues for you, we recommend you first take a look at how your service is built and configured. We monitor services once every 5 minutes and this should not cause noticeable load to any web service. If performance issues is not the reason you want to stop our monitoring, then I urge you to reconsider: Does monitoring take anything away from you? Do your users appreciate having availability statistics publicly available? If you have a good reason for us to not monitor you besides performance, I ask you to comment on this post and we can discuss your case.

In case your mind is made up, you can forbid us from monitoring your service. You can either upload a catch-all disallow-all robots.txt on your server, or place the following directives in your robots.txt:

User-agent: spatineo
Disallow: /

Please note that both “User-agent” and “spatineo” here are case sensitive and should be written as in the example above. Also keeping in mind that directives are read in order and robots use only the first matching directive. So place the above directive as the first directive or at least before User-agent *.

If you think you have already set up blocking correctly, but we are still monitoring your service, please do the following:

  • Make sure the character cases in your robots.txt match the above example (User-agent != User-Agent).
  • Check that your robots.txt does not have conflicting rules which would specifically allow our monitoring.
  • If you only just changed the file, you can update our records manually: enter the complete URL to your service into our search engine. This will update the records for that service and monitoring will cease.
  • In case this does not stop the requests, please post below or contact us via this page

Spatial web services & data journalism, the Talvivaara case

We had an interesting real-world case of using open environmental data for journalism a couple of weeks ago in Finland. In the early hours of Saturday the 10th of November Yle, the Finnish public broadcasting company, published a background news item at their site related to the continued pollution leakage at Talvivaara mining site in Sodankylä, Finland.

In the post “Kaikki Talvivaaran alueesta” (“All about Talvivaara area”) they point to the interactive mashup map of the mining area, including natural protection areas, mining reservations etc., aggregated at the Paikkatietoikkuna geoportal of the Finnish National Land Survey.

A few hours later the map was rendered practically useless because of the serious performance problems of the background WMS services providing the data.

The map window application at Paikkatietoikkuna makes it possible for any user to aggregate and publish web maps with their preferred selection of visualized geospatial data layer provided by the various Finnish governmental organizations. The data layers are served by the WMS servers hosted by the organizations, the application only provides an interactive graphical user interface for displaying them as a mashup. In this case Yle reporters had been able to make an up-to-date, interactive map covering soil types, lakes and rivers, ground water reserves, land claims for minings and natural protection areas just by selecting the layers and publishing the link pointing at it in their news item.

The data layers in the mashup was provided by the Geological Survey of Finland (soil types), Finnish Environment Institute (river, lake, natural water reserves and natural protection area) and the Finnish Ministry of Employment and the Economy (the mining-related information). The attached report from our Spatineo Monitor clearly shows the increased response times for all the WMS servers providing the selected data layers starting in the morning of 10th Nov 2012. At 04 UTC (06 local time) the Soil type service were struggling with the first traffic peak, and by 06 UTC the server was unresponsive. The situation started to improve only at evening, about 17 UTC.

The one month time series of one of the services (Soil data) shows the average response times on10th Nov. were considerably above normal for that service:

It seems that the journalists are really starting to take advantage of the public open geospatial data resources and easily available web map tools like Paikkatietoikkuna, but the data providers are not very well prepared for even pretty minor “slashdot effects” caused by sudden increased traffic at their services.

We at Spatineo are quite glad to be able to report things like this based on our continuous monitoring of thousands of spatial web services around the world. It confirms us that our proactive monitoring strategy is the right one: In most cases we have been collecting the performance data already before our customers experience performance problems in their spatial web services.

OGC to switch to WC3 XLink in July 2012

Open Geospatial Consortium (OGC) will make a backwards incompatible change to it’s XML Schema files of a large part of it’s standards in July 21st 2012. This change is done as a global corrigendum to move into using the W3C XLink version 1.1 instead of the OGC-specific XLink XML Schema implementation. See my previous post at for details on the reasons behind this pretty large-scale change.

Basically the change is quite a simple one:

  • all existing OGC standards that reference the OGC XLink shall be updated to reference the W3C XLink 1.1 schema and
  • going forward any new standards work shall only reference the W3C XLink schema.

By far the most used XLink attribute in OGC schemas is the locator attribute xlink:href, which contains an URL pointing to a link between two XML documents. In the XML Schema documents, the XLink href attribute is usually included in a complex type by adding an attribute group named simpleLink. In schemas using GML this is often done indirectly by using a pre-defined gml:AssociationAttributeGroup:

<complexType name="ReferenceType">
    gml:ReferenceType is intended to be used in application schemas directly,
    if a property element shall use a "by-reference only" encoding.
  <attributeGroup ref="gml:OwnershipAttributeGroup"/>
  <attributeGroup ref="gml:AssociationAttributeGroup"/>

The gml:AssociationAttributeGroup GML 3.2.1 (before the XLink corrigendum) in turn refers to the simpleLink attribute group defined in the XLink namespace:

<attributeGroup name="AssociationAttributeGroup">
    XLink components are the standard method to support hypertext referencing in XML. An XML Schema 
    attribute group, gml:AssociationAttributeGroup, is provided to support the use of Xlinks as 
    the method for indicating the value of a property by reference in a uniform manner in GML.
  <attributeGroup ref="xlink:simpleLink"/>
  <attribute name="nilReason" type="gml:NilReasonType"/>
  <attribute ref="gml:remoteSchema">

In non-corrected GML 3.2.1 schema files the XLink namespace is imported from the OGC version of the XLink schema:

<import namespace="" schemaLocation=""/>

In this file the simpleLink attributeGroup is defined like this:

<attribute name="href" type="anyURI"/>
<attributeGroup name="simpleLink">
  <attribute name="type" type="string" fixed="simple" form="qualified"/>
  <attribute ref="xlink:href" use="optional"/>
  <attribute ref="xlink:role" use="optional"/>
  <attribute ref="xlink:arcrole" use="optional"/>
  <attribute ref="xlink:title" use="optional"/>
  <attribute ref="xlink:show" use="optional"/>
  <attribute ref="xlink:actuate" use="optional"/>

The thing that will change in July 2012 is all the schema files of all affected OGC standards will modified to point to the W3C official XLink 1.1 schema available at The href attribute definition in the W3C XLink schema is only slightly different from the OGC version:

<xs:attribute name="href" type="xlink:hrefType"/>
<xs:simpleType name="hrefType">
  <xs:restriction base="xs:anyURI"/>
<xs:attributeGroup name="simpleAttrs">
  <xs:attribute ref="xlink:type" fixed="simple"/>
  <xs:attribute ref="xlink:href"/>
  <xs:attribute ref="xlink:role"/>
  <xs:attribute ref="xlink:arcrole"/>
  <xs:attribute ref="xlink:title"/>
  <xs:attribute ref="xlink:show"/>
  <xs:attribute ref="xlink:actuate"/>

This means that all XML files using xlink:href attribute valid against the OGC XLink schema are also valid against the W3C XLink 1.1 schema. However because the attribute group “simpleLink” in the OGC schema is called “simpleAttrs” in the W3C schema, the XML schema files using this attribute group will no longer be valid after the change. To fix this all the schema files using the “simpleLink” attribute group will have to be changed to use the “simpleAttrs” instead.

This change has to be done simultaneously to as many schema files as possible, because the XML validators become confused if they encounter two different schema versions of the same XML namespace. In addition to the OGC’s schema files, the same change should also be done to any other schemas using the OGC version of the XLink schema available at To force the users to do this change, the OGC Architecture Board has decided to remove the OGC XLink schema file along with the other schema changes.

According to a mailing list post by Carl Reed, the CTO of the OGC, on 12th April 2012, at least the following OGC standards are affected by this change:

  • All versions of WM context
  • All versions of GML since version 2.0.0
  • All profiles of GML since 2.0.0
  • Image CRSs
  • All versions of OpenLS since version 1.1.0
  • All versions of OWS Common since 1.0.0
  • Symbology Encoding 1.0
  • All versions of SLD since 1.0.0
  • All versions of SensorML (including 2.0)
  • All versions of SWE Common
  • Table Join Service
  • All versions of Web Coverage Service
  • Web Feature Service 2.0
  • Web Map Service 1.3
  • WMTS
  • Web Processing Service

There are probably other schemas and standards in addition to this list because the schemas are inter-linked. Especially the different version of GML are used in many other OGC schemas.

Further quoting the announcement from Carl Reed about the OGC actions to be taken:

The target date for implementing change is the weekend of July 21, 2012.

The process will be:

  • Scan schema repository for import of xlink to find a list of standards that use xlink.
  • Also scan for strings such as Gml:ReferenceType to find other possible places that xlink is required.
  • Whatever schema uses any of XLink schema components will need to replace the schema location. We need to do this for all schemas that import xlink. All these changes will be done to a copy of the existing OGC schema repository.
  • For software developers, they need to patch their products to use the revised OGC schemas.
  • Everyone will need to delete local copies, get a new copy from the OGC schema repository, and use the new schemas. There is also the possibility to use a tool such as the OASIS XML Catalogue to override the required change and to continue using the old XLink.
  • In July, we will then issue one global corrigendum for all the affected standards. Essentially, the current OGC schema repository will be replaced with the schemas that have been changed (and tested). The actual standards documents will not change – only the schemas. OGC policy is that the schemas are normative and that if there are differences between a standards document and a schema, then the schemas are normative.

This is pretty much the approach I expected the OGC to take when I wrote about this in January.

If you are running or developing software dealing with OGC compliant data or services you really should check that it will still work with the modified versions of the schema files. You can begin testing your software as soon as the modified OGC schema files are made available in the alternative OGC schema repository. One of the simplest ways to test this is to use the OASIS XML Catalog to temporarily redirect the requests for the schema files of the modified standards’ namespaces to the alternative OGC schema locations. If your software supports the XML Catalog a catalog.xml file with directives something like the following should do the trick (assuming that the modified OGC schemas would be made available under the domain

<!DOCTYPE catalog
  PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"
  <rewriteURI uriStartString=""
		rewritePrefix="" />
  <rewriteURI uriStartString=""
		rewritePrefix="" />
  [etc for all affected standards]

When an XML validator using this catalog needs to fetch any xml files from URLs beginning with “” it will try to fetch them from “” instead. The benefit from this approach is that you will be able to simulate schema switch-over well before the actual change in July without making any changes to your code or data files.

You can also use the XML Catalog if you find that you must delay the schema changes for your local system. To do this you can take local copies from the unmodified OGC schema files and create another set of rewriteURI directives. Assuming that the local schema files are stored under /etc/xml/schemas/original/ogc/:

<!DOCTYPE catalog
  PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
<catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"
  <rewriteURI uriStartString=""
		rewritePrefix="file:///etc/xml/schemas/original/ogc/gml/" />
  <rewriteURI uriStartString=""
		rewritePrefix="file:///etc/xml/schemas/original/ogc/wfs/" />

What is an O&M Observation and why should you care?

Observations & Measurements (O&M) is an international standard for modeling observation events and describing their relations to the target spatial objects under observation, the measured properties & measurement procedure, and the captured data resulting from those observation events. It’s based on Geography Markup Language (GML), another standard by the Open Geospatial Consortium (OGC) enabling a common base for it’s notation of location based information.

In addition to the most obvious cases of representing records of scientific measurement data, the O&M model is also used for modeling predicted information like weather forecasts. Because of it’s general ability to model perceived values of spatial objects’ properties at specific times, it’s a good fit for many kinds of application domains where it’s necessary to capture time-based changes on objects of interest.

The basic O&M observation event concepts.

The O&M conceptual model is published both as an Open Geospatial Consortium (OGC) Abstract Specification Topic 20 and as an ISO standard with number ISO/DIS 19156. The XML implementation of O&M model is also an OGC standard “Observations and Measurements – XML Implementation“. The origins of the O&M is in the Sensor Web Enablement (SWE) initiative of the OGC. It was needed as the common standardized data model for handling the measurement events occurring in different kinds of sensors from thermometers inside an industrial process to satellites taking images of the Earth from the space. Together with other SWE framework open standards like SensorML and Sensor Observation Service (SOS), O&M provides a system-independent, Internet-enabled ways of data exchange between different parts of sensor networks and other systems using the captured sensor information.

Even though the O&M model was originally created for modeling measurement acts that have already happened, there is no technical difficulty in using the same model also for describing acts of estimating the values of some properties of spatial objects at some point in the future. After all, event the most precise measurements are still only estimations of the actual properties of the target objects, limited by the method and the tools used, as well as our capabilities of interpreting the measurement results. The captured data itself is often very similar in both measurement and prediction cases, so it makes sense to try to store and deliver those data sets using the the same basic concepts.

One of the facts that makes the O&M model interesting right now is the increasing affordability of IP-based environmental sensors: these days almost anyone can afford to buy a basic weather observation station, place it in their backyard, and plug it in the Internet for sharing the data with others. Or buy an Internet-connected web camera. This also means that it’s becoming possible for anyone to gather and refine detailed environmental information about the world around us, both locally and globally. What used to the playground of the big, closed national and international institutes and governmental offices, is now opening up also to ordinary citizens. Of course this also means, like in everything based on the Internet, that as the amount of information and the heterogeneity of the sources producing it grows, the quality range of the available information also inevitably becomes wider.

The Sensor Web movement is so promising that also the organizations that used to deploy and maintain their own sensor networks with their proprietary data and control interfaces built for their specific software and hardware systems, are moving towards these open standards. Even though they might not put their data publicly in the Internet, they definitely want to take advantage of the IP-based networks for communicating, and they’s love to be able to easily switch between two sensor equipment boxes made by different vendors in plug-and-play fashion. The extra network traffic caused by a higher level communication protocols and more verbose content encoding is less and less of an issue in this ever more broadband world of ours.

Still, it would be nice if the increasing amounts of sensor data collected by publicly funded organizations would also be made available to the public, wouldn’t it? In many cases it already is available for someone who knows where to ask. Sometimes it’s even freely available in the Internet, like the various public web cams, but mostly it’s still accessible only to professionals. This is bound to change gradually however as international legislation aiming at data opening and harmonization, like the EU INSPIRE directive in Europe, is being implemented around the world. The O&M concepts form the basis of the EU-widely harmonized INSPIRE data models for meteorological, climatological and air quality information, as well as for physical oceanographic measurement data and the structure and the capabilities of the various environmental observation networks. This basically means that in the near future the ordinary citizens will be able to access the environmental data provided by the government officials in pretty much using the same protocols and data formats that they’re used to while accessing their neighbor’s off-the-self sensor equipment. Ain’t that cool?

I’m currently involved in the international expert teams on behalf of our customer the Finnish Meteorological Institute for creating the data specifications and writing guidelines for some of the O&M based INSPIRE data sets. We’re currently finalizing our work on the guidelines documents, but the actual work to make the INSPIRE spatial data infrastructure reality goes on of course. Fortunately there are deadlines: initial bunch of the view and download services for these INSPIRE data sets should be publicly available in May 2013, and even the last bits should be fully in INSPIRE compliant shape by 2020.